Interventions for Interventions for Clients with Clients with

DysrhythmiasDysrhythmias

Cardiac Cardiac dysrhythmias are dysrhythmias are disturbances of cardiac electrical disturbances of cardiac electrical impulse formation, conduction, or impulse formation, conduction, or bothboth

Review of Cardiac Review of Cardiac Electrophysiology Electrophysiology

AutomaticityAutomaticity (spontaneous depolarization) is the ability of (spontaneous depolarization) is the ability of cardiac cells to generate an electrical impulse spontaneously cardiac cells to generate an electrical impulse spontaneously and repetitively. Normally, only primary pacemaker cells and repetitively. Normally, only primary pacemaker cells possess this property. Under certain conditions, such as possess this property. Under certain conditions, such as myocardial ischemia (decreased blood flow) and infarction myocardial ischemia (decreased blood flow) and infarction (cell death), any cardiac cell may exhibit this property, (cell death), any cardiac cell may exhibit this property, generating electrical impulses independently and creating generating electrical impulses independently and creating dysrhythmiasdysrhythmias

ExcitabilityExcitability is the ability of nonpacemaker cardiac cells to is the ability of nonpacemaker cardiac cells to respond to an electrical impulse generated from pacemaker respond to an electrical impulse generated from pacemaker cells and to depolarize. Depolarization occurs when the cells and to depolarize. Depolarization occurs when the normally negatively charged cells develop a positive chargenormally negatively charged cells develop a positive charge

ConductivityConductivity is the ability to transmit an electrical stimulus is the ability to transmit an electrical stimulus from cell membrane to cell membrane. Consequently, ex from cell membrane to cell membrane. Consequently, ex citable cells depolarize in rapid succession from cell to cell citable cells depolarize in rapid succession from cell to cell until all cells have depolarized. This wave of depolarization until all cells have depolarized. This wave of depolarization gives rise to the deflections of the electrocardiogram (ECG) gives rise to the deflections of the electrocardiogram (ECG) waveforms that are recognized as the P wave and the QRS waveforms that are recognized as the P wave and the QRS complexcomplex

Review of Cardiac Review of Cardiac ElectrophysiologyElectrophysiology

ContractilityContractility is the ability of atrial and ventricular is the ability of atrial and ventricular muscle cells to shorten their fiber length in response to muscle cells to shorten their fiber length in response to electricalelectrical stimulation, generating sufficient pressure to stimulation, generating sufficient pressure to propel blood forward. This is the mechanical activity of propel blood forward. This is the mechanical activity of the heartthe heart

Action potential – Action potential – The cardiac cell membrane The cardiac cell membrane (sarcolemma) exhibits selective permeability to ions. An (sarcolemma) exhibits selective permeability to ions. An ion is an electrically charged particle. This creates an ion is an electrically charged particle. This creates an electrical imbalance, known as an electrical imbalance, known as an action po tential, action po tential, across the cell membrane. The cardiac cell at rest has across the cell membrane. The cardiac cell at rest has an internal negative charge, whereas the charge outside an internal negative charge, whereas the charge outside the cell is positive. This state of electrical imbalance of the cell is positive. This state of electrical imbalance of the resting cell is called the resting cell is called resting membrane potentialresting membrane potential

Cardiac Conduction Cardiac Conduction System System

Sinoatrial node Sinoatrial node – Electrical impulses at 60 to 100 Electrical impulses at 60 to 100

beats/minbeats/min Atrioventricular junctional area Atrioventricular junctional area Bundle branch systemBundle branch system

Electrocardiography Electrocardiography Electrocardiogram (ECG) - provides a graphic Electrocardiogram (ECG) - provides a graphic

represen tation, or picture, of cardiac activityrepresen tation, or picture, of cardiac activity

A lead provides one view of the heart's electrical A lead provides one view of the heart's electrical activity. Multiple leads, or views, can be obtained. activity. Multiple leads, or views, can be obtained. Electrode placement is the same for male and Electrode placement is the same for male and female clients.female clients.

Lead systems are made up of a positive pole and Lead systems are made up of a positive pole and a negative pole. An imaginary line joining these a negative pole. An imaginary line joining these two poles is called the two poles is called the lead axislead axis. .

The direction of electrical current flow in the heart The direction of electrical current flow in the heart is the is the cardiac axiscardiac axis. .

The relationship between the cardiac axis and the The relationship between the cardiac axis and the lead axis is responsible for the deflections seen lead axis is responsible for the deflections seen on the ECG patternon the ECG pattern

ElectrocardiographyElectrocardiography Limb leadsLimb leads Standard bipolar limb leads consist of three leads that each Standard bipolar limb leads consist of three leads that each

measure the electrical activity between two points, and a measure the electrical activity between two points, and a fourth lead (right leg) that acts solely as a ground electrode. Of fourth lead (right leg) that acts solely as a ground electrode. Of the three measuring leads, the right arm is always negative, the three measuring leads, the right arm is always negative, the left leg is always positive, and the left arm can be either the left leg is always positive, and the left arm can be either positive or negative. positive or negative.

Bipolar leads can be obtained by using a monitor with either Bipolar leads can be obtained by using a monitor with either three or five electrode cables or a 12-lead ECG machine. three or five electrode cables or a 12-lead ECG machine.

Leads I, II, and III are bipolar leads.Leads I, II, and III are bipolar leads. Unipolar limb leads consist of a positive electrode only. Unipolar limb leads consist of a positive electrode only. These leads can be obtained only by using a monitor with four These leads can be obtained only by using a monitor with four

or five electrode cables or a 12-lead ECG machine. The or five electrode cables or a 12-lead ECG machine. The unipolar limb leads are aVR, aVL, and aVF, with unipolar limb leads are aVR, aVL, and aVF, with a a meaning meaning augmented. augmented. V V is a designation for a unipolar lead. The third is a designation for a unipolar lead. The third letter denotes the positive electrode placement: letter denotes the positive electrode placement: R R for right for right arm, arm, L L for left arm, and for left arm, and F F for foot (left leg). for foot (left leg).

The positive electrode is at one end of the lead axis. The other The positive electrode is at one end of the lead axis. The other end is the center of the electrical field, at approximately the end is the center of the electrical field, at approximately the center of the heartcenter of the heart

ElectrocardiographyElectrocardiography Chest leadsChest leads Chest (precordial) leads are also unipolar, or V, leads and Chest (precordial) leads are also unipolar, or V, leads and

therefore can be obtained only from a monitor with five therefore can be obtained only from a monitor with five electrode cables or a 12-lead ECG machine, which usually electrode cables or a 12-lead ECG machine, which usually has 10 electrode cables. has 10 electrode cables.

There are six chest leads, determined by the placement of There are six chest leads, determined by the placement of the chest electrode. the chest electrode.

The four limb electrodes are placed on the extremities, as The four limb electrodes are placed on the extremities, as designated on each electrode (right arm, left arm, right leg, designated on each electrode (right arm, left arm, right leg, and left leg). and left leg).

The fifth (chest) electrode on a monitor system is the The fifth (chest) electrode on a monitor system is the positive, or exploring, electrode and is placed in one of six positive, or exploring, electrode and is placed in one of six designated positions to obtain the desired chest lead. designated positions to obtain the desired chest lead.

With a 12-lead ECG, four leads are placed on the limbs and With a 12-lead ECG, four leads are placed on the limbs and six are placed on the chest, eliminating the need to move six are placed on the chest, eliminating the need to move any electrodes about the chestany electrodes about the chest

ElectrocardiographyElectrocardiography Continuous electrocardiographic monitoringContinuous electrocardiographic monitoring For continuous electrocardiographic (ECG) monitoring, the For continuous electrocardiographic (ECG) monitoring, the

electrodes are not placed on the limbs, because movement electrodes are not placed on the limbs, because movement of the extremities causes "noise," or motion artifact, on the of the extremities causes "noise," or motion artifact, on the ECG signal. The nurse places the electrodes on the trunk, a ECG signal. The nurse places the electrodes on the trunk, a more stable area, to minimize such artifacts and to obtain a more stable area, to minimize such artifacts and to obtain a clearer signal. The nurse places the electrodes as follows:clearer signal. The nurse places the electrodes as follows:– Right arm electrode just below the right clavicleRight arm electrode just below the right clavicle– Left arm electrode just below the left clavicleLeft arm electrode just below the left clavicle– Right leg electrode on the lowest palpable rib, on the right Right leg electrode on the lowest palpable rib, on the right

midclavicular linemidclavicular line– Left leg electrode on the lowest palpable rib, on the leftLeft leg electrode on the lowest palpable rib, on the left

midclavicular linemidclavicular line– Fifth electrode placed to obtain one of the six chest leadsFifth electrode placed to obtain one of the six chest leads

With this placement, the monitor lead select control may be With this placement, the monitor lead select control may be changed to provide lead I, II, III, aVR, aVL, or aVF or one changed to provide lead I, II, III, aVR, aVL, or aVF or one chest lead. The monitor automatically alters the polarity of chest lead. The monitor automatically alters the polarity of the electrodes to provide the lead selectedthe electrodes to provide the lead selected

ElectrocardiographyElectrocardiography TelemetryTelemetry ECG cables may be attached directly to a wall-ECG cables may be attached directly to a wall-

mounted monitor (a hard-wired system) if the mounted monitor (a hard-wired system) if the client's activity is restricted to bedrest and sitting client's activity is restricted to bedrest and sitting in a chair, as in a critical care unit. in a chair, as in a critical care unit.

For an ambulatory client, the ECG cable is attached For an ambulatory client, the ECG cable is attached to a battery-operated transmitter (a to a battery-operated transmitter (a telemetry telemetry systemsystem) held in a pouch worn by the client. ) held in a pouch worn by the client.

The ECG is transmitted via antennae located in The ECG is transmitted via antennae located in strategic places, usually in the ceiling, to a remote strategic places, usually in the ceiling, to a remote monitor. This device allows freedom of movement monitor. This device allows freedom of movement within a certain radius without losing transmission within a certain radius without losing transmission of the ECGof the ECG

Electrocardiographic Complexes, Electrocardiographic Complexes, Segments, and IntervalsSegments, and Intervals

P waveP wave PR segment PR segment PR interval - it normally measures from 0.12 to PR interval - it normally measures from 0.12 to

0.20 second0.20 second QRS complex QRS complex QRS duration - it normally measures from 0.04 to QRS duration - it normally measures from 0.04 to

0.10 second0.10 second ST segment - it is normally not elevated more ST segment - it is normally not elevated more

than 1 mm or depressed more than 0.5 mm from than 1 mm or depressed more than 0.5 mm from the isoelectric line. Its amplitude is measured at a the isoelectric line. Its amplitude is measured at a point 1.5 to 2 mm after the J-pointpoint 1.5 to 2 mm after the J-point

T wave T wave U waveU wave QT intervalQT interval

Electrocardiographic Rhythm Electrocardiographic Rhythm Analysis Analysis

Normal RhythmsNormal Rhythms Normal sinus rhythm - is the rhythm Normal sinus rhythm - is the rhythm

originating from the sinoatrial (SA) node originating from the sinoatrial (SA) node (dominant pacemaker) that meets the (dominant pacemaker) that meets the following electrocardiographic (ECG) following electrocardiographic (ECG) criteria:criteria:– Rhythm: Rhythm: Atrial and ventricular rhythms regularAtrial and ventricular rhythms regular– Rate: Rate: Atrial and ventricular rates of 60 to 100 Atrial and ventricular rates of 60 to 100

beats/minbeats/min– P waves: P waves: Present, consistent configuration, one Present, consistent configuration, one

P waveP wavebefore each QRS complexbefore each QRS complex

– PR interval: PR interval: 0.12 to 0.20 second and constant0.12 to 0.20 second and constant– QRS duration: QRS duration: 0.04 to 0.10 second and constant0.04 to 0.10 second and constant

Normal RhythmsNormal Rhythms

Sinus arrhythmiaSinus arrhythmia Sinus arrhythmia is a variant of NSR. It Sinus arrhythmia is a variant of NSR. It

results from changes in intrathoracic results from changes in intrathoracic pressure during breathing. pressure during breathing.

In this context the term In this context the term arrhythmia arrhythmia does does not denote an absence of rhythm, as the not denote an absence of rhythm, as the term suggests. term suggests.

Instead, the heart rate increases slightly Instead, the heart rate increases slightly during inspiration and decreases slightly during inspiration and decreases slightly during exhalationduring exhalation

Dysrhythmias Dysrhythmias Tachydysrhythmias - are heart rates greater Tachydysrhythmias - are heart rates greater

than 100 beats/minthan 100 beats/min Bradydysrhythmias - are characterized by a Bradydysrhythmias - are characterized by a

heart rate less than 60 beats/minheart rate less than 60 beats/min Premature complexes - are early complexes. Premature complexes - are early complexes.

They occur when a cardiac cell or cell group, They occur when a cardiac cell or cell group, other than the sinoatrial (SA) node, becomes other than the sinoatrial (SA) node, becomes irritable and fires an impulse before the next irritable and fires an impulse before the next sinus impulse is generated. This abnormal sinus impulse is generated. This abnormal focus is called an focus is called an ectopic focus ectopic focus and may be and may be generated by atrial, junctional, or ventricular generated by atrial, junctional, or ventricular tissuetissue

DysrhythmiasDysrhythmias Repetitive rhythms - premature complexes may occur Repetitive rhythms - premature complexes may occur

repetitively in a rhythmic fashion repetitively in a rhythmic fashion – bigeminy exists when normal complexes and premature bigeminy exists when normal complexes and premature

complexes occur alternately in a repetitive two-beat pattern, complexes occur alternately in a repetitive two-beat pattern, with a pause occurring after each premature complex so that with a pause occurring after each premature complex so that complexes occur in pairs.complexes occur in pairs.

– trigeminy is a repetitive three-beat pattern, usually occurring as trigeminy is a repetitive three-beat pattern, usually occurring as two sequential normal complexes followed by premature two sequential normal complexes followed by premature complex and a pause, with the same pattern repeating itself in complex and a pause, with the same pattern repeating itself in triplets.triplets.

– quadrigeminy - is a repetitive four-beat pattern, usually quadrigeminy - is a repetitive four-beat pattern, usually occurring as three sequential normal complexes fol lowed by a occurring as three sequential normal complexes fol lowed by a premature complex and a pause, with the same pattern premature complex and a pause, with the same pattern repeating itself in a four-beat patternrepeating itself in a four-beat pattern

Escape complexes and rhythms - occur when the SA node Escape complexes and rhythms - occur when the SA node fails to discharge or is blocked or when a sinus impulse fails fails to discharge or is blocked or when a sinus impulse fails to depolarize the ventricles because of an atrioventricular to depolarize the ventricles because of an atrioventricular (AV) nodal block(AV) nodal block

Sinus tachycardiaSinus tachycardia When the rate of SA node discharge exceeds 100 When the rate of SA node discharge exceeds 100

beats/minbeats/min Clinical manifestations - the client may be Clinical manifestations - the client may be

asymptomatic except for the in creased pulse asymptomatic except for the in creased pulse rate. However, if the rhythm is not well tolerated, rate. However, if the rhythm is not well tolerated, he or she may become symptomatic. The client is he or she may become symptomatic. The client is assessed for fatigue, weakness, shortness of assessed for fatigue, weakness, shortness of breath, orthopnea, neck vein distention, breath, orthopnea, neck vein distention, decreased oxygen saturation, and decreased decreased oxygen saturation, and decreased blood pressure. The nurse also assesses for blood pressure. The nurse also assesses for restlessness and anxiety from decreased cerebral restlessness and anxiety from decreased cerebral perfusion and for decreased urine output from perfusion and for decreased urine output from decreased renal perfusion. The adult client may decreased renal perfusion. The adult client may experience anginal pain. The electrocardiographic experience anginal pain. The electrocardiographic (ECG) pattern may show T-wave inversion or ST-(ECG) pattern may show T-wave inversion or ST-segment elevation or depression in response to segment elevation or depression in response to myocardial ischemiamyocardial ischemia

Sinus tachycardia (heart rate, 110 beats/min; PR interval, 0.12 second; QRS complex, 0.08 second)

Sinus tachycardiaSinus tachycardia Interventions Interventions The goal is to decrease the heart rate to normal levels by The goal is to decrease the heart rate to normal levels by

treating the underlying cause. treating the underlying cause. For example, if the client has angina, the nurse administers For example, if the client has angina, the nurse administers

oxygen, helps the client to rest, and administers nitroglycerin oxygen, helps the client to rest, and administers nitroglycerin or morphine as prescribed. or morphine as prescribed.

Diuretics and inotropic agentsDiuretics and inotropic agents may be given for heart failure. may be given for heart failure. The nurse initiates intravascular volume replacement for The nurse initiates intravascular volume replacement for hypovolemia, administers antipyretics and antibiotics to the hypovolemia, administers antipyretics and antibiotics to the client with fever and infection, or provides comfort measures client with fever and infection, or provides comfort measures and administers analgesics or opioids to the client with and administers analgesics or opioids to the client with noncardiac pain, as ordered.noncardiac pain, as ordered.

The nurse collaborates with the respiratory therapist when The nurse collaborates with the respiratory therapist when indicated to oxygenate and suction the client with hypoxemia indicated to oxygenate and suction the client with hypoxemia from excessive airway secretions. from excessive airway secretions.

Beta-adrenergic blocking agents may be prescribed for the Beta-adrenergic blocking agents may be prescribed for the client with inappropriate sympathetic nervous system client with inappropriate sympathetic nervous system stimulation. stimulation.

Emotional support and relevant teaching are important for the Emotional support and relevant teaching are important for the client and familyclient and family

Sinus BradycardiaSinus Bradycardia

Rate of sinus node discharge < 60 Rate of sinus node discharge < 60 beats/minbeats/min

Clinical manifestations - the client Clinical manifestations - the client may be asymptomatic, except for the may be asymptomatic, except for the decreased pulse rate. However, at decreased pulse rate. However, at times the rhythm may not be well times the rhythm may not be well tolerated. The nurse assesses the tolerated. The nurse assesses the client for dizziness, weakness, client for dizziness, weakness, syncope, confusion, hypotension, syncope, confusion, hypotension, diaphoresis, shortness of breath, diaphoresis, shortness of breath, ventricular ectopy, and anginal painventricular ectopy, and anginal pain

Sinus bradycardia (heart rate, 52 beats/min; PR interval, 0.18 sec ond; QRS complex, 0.08 second)

Sinus BradycardiaSinus Bradycardia InterventionsInterventions If the client is symptomatic and the underlying If the client is symptomatic and the underlying

cause cannot be determined, the treatment of cause cannot be determined, the treatment of choice is atropine administration, given as choice is atropine administration, given as prescribed to increase the heart rate to prescribed to increase the heart rate to approximately 60 beats/min. approximately 60 beats/min.

Oxygen should be applied. If the heart rate does Oxygen should be applied. If the heart rate does not increase sufficiently, the nurse may apply an not increase sufficiently, the nurse may apply an external pacemaker to increase the heart rate and external pacemaker to increase the heart rate and notify the physician. notify the physician.

However, if atropine administration succeeds in However, if atropine administration succeeds in achieving an adequate heart rate but the client achieving an adequate heart rate but the client remains hypotensive, the nurse initiates remains hypotensive, the nurse initiates intravascular volume replacement, as ordered, intravascular volume replacement, as ordered, rather than administering another dose of atropine. rather than administering another dose of atropine. Excessive atropine may induce tachycardiaExcessive atropine may induce tachycardia

Premature Atrial Premature Atrial ComplexesComplexes

Ectopic focus of atrial tissue fires an impulse Ectopic focus of atrial tissue fires an impulse before the next sinus impulse is due.before the next sinus impulse is due.

Clinical manifestations - the client is usually Clinical manifestations - the client is usually asymptomatic, except for possible heart asymptomatic, except for possible heart palpitations, because PACs usually have no palpitations, because PACs usually have no hemodynamic consequenceshemodynamic consequences

Interventions - no intervention is usually needed Interventions - no intervention is usually needed except to treat the cause, such as heart failure or except to treat the cause, such as heart failure or valvular disease. The nurse administers valvular disease. The nurse administers prescribed type antidysrhythmics, such as prescribed type antidysrhythmics, such as quinidine and procainamide (Pronestyl), or other quinidine and procainamide (Pronestyl), or other drugs such as digitalis and propranolol (Inderal, drugs such as digitalis and propranolol (Inderal, Apo-Propranolol). Measures to reduce stress are Apo-Propranolol). Measures to reduce stress are also initiated, and the client is taught to avoid also initiated, and the client is taught to avoid substances known to increase atrial irritabilitysubstances known to increase atrial irritability

Normal sinus rhythm with a premature atrial complex (PAC) at arrow

Supraventricular Tachycardia Supraventricular Tachycardia

Rapid stimulation of atrial tissue Rapid stimulation of atrial tissue occurs at a rate of 100 to 280 occurs at a rate of 100 to 280 beat/min with a mean of 170 beat/min with a mean of 170 beats/min in adults.beats/min in adults.

Paroxysmal supraventricular Paroxysmal supraventricular tachycardia rhythm is tachycardia rhythm is intermittent and terminated intermittent and terminated suddenly with or without suddenly with or without intervention.intervention.

Sustained supraventricular tachycardia in a client with Wolff-Parkinson-White syndrome. Heart rate is 200

beats/min

Supraventricular TachycardiaSupraventricular Tachycardia

Clinical manifestations - the clinical Clinical manifestations - the clinical manifestations depend on the duration of manifestations depend on the duration of the SVT and the rate of the ventricular the SVT and the rate of the ventricular response. In clients with a sustained rapid response. In clients with a sustained rapid ventricular response, the nurse assesses ventricular response, the nurse assesses for palpitations, weakness, fatigue, for palpitations, weakness, fatigue, shortness of breath, nervousness, anxiety, shortness of breath, nervousness, anxiety, hypotension, and syncope. Hemodynamic hypotension, and syncope. Hemodynamic deterioration may occur in the client with deterioration may occur in the client with cardiac disease, causing angina, heart cardiac disease, causing angina, heart failure, and shock. With a nonsustained or failure, and shock. With a nonsustained or slower ventricular response, the client may slower ventricular response, the client may be asymptomatic except for transient be asymptomatic except for transient palpitationspalpitations

Supraventricular TachycardiaSupraventricular Tachycardia

Interventions Interventions If SVT occurs in a healthy person and terminates If SVT occurs in a healthy person and terminates

spontaneously, no intervention is necessary other than spontaneously, no intervention is necessary other than eliminating identified causative factors. eliminating identified causative factors.

If it is recurrent, the client should be studied in the If it is recurrent, the client should be studied in the electrophysiology laboratory. The preferred treatment for electrophysiology laboratory. The preferred treatment for recurrent SVT is radiofrequency catheter ablation. In sustained recurrent SVT is radiofrequency catheter ablation. In sustained SVT with a rapid ventricular response, the goals of treatment SVT with a rapid ventricular response, the goals of treatment are to decrease the ventricular response, convert the are to decrease the ventricular response, convert the dysrhythmia to a sinus rhythm, and treat the cause. Vagal dysrhythmia to a sinus rhythm, and treat the cause. Vagal stimulation (e.g., carotid massage) may be successful, but stimulation (e.g., carotid massage) may be successful, but often only transiently, and must be performed only by a often only transiently, and must be performed only by a physician.physician.

The nurse administers oxygen and prescribed antidysrhythmic The nurse administers oxygen and prescribed antidysrhythmic drugs, which slow the ventricular rate by increasing the AV drugs, which slow the ventricular rate by increasing the AV block. block.

In the severely compromised client, the nurse may assist the In the severely compromised client, the nurse may assist the physician in attempting atrial overdrive pacing or in delivering physician in attempting atrial overdrive pacing or in delivering a synchronized electrical shock (cardioversion) to reestablish a synchronized electrical shock (cardioversion) to reestablish an organized rhythm and regain cardiac stabilityan organized rhythm and regain cardiac stability

Atrial FlutterAtrial Flutter Rapid atrial depolarization occurring at a rate of Rapid atrial depolarization occurring at a rate of

250 to 350 times per minute250 to 350 times per minute Clinical manifestations - the clinical Clinical manifestations - the clinical

manifestations depend on the rate of ventricular manifestations depend on the rate of ventricular response. The nurse assesses the client for response. The nurse assesses the client for palpitations, weakness, fatigue, shortness of palpitations, weakness, fatigue, shortness of breath, nervousness, anxiety, syncope, angina, breath, nervousness, anxiety, syncope, angina, and evidence of heart failure and shock. Carotid and evidence of heart failure and shock. Carotid sinus massage transiently decreases the sinus massage transiently decreases the ventricular rate to facilitate rhythm interpretation ventricular rate to facilitate rhythm interpretation but can be performed only by the physician. The but can be performed only by the physician. The client with a normal ventricular rate is usually client with a normal ventricular rate is usually asymptomaticasymptomatic

Atrial flutter (F) with 4:1 block. The atrial rate is 280 beats/min; the ventricular rate is 70 beats/min

Atrial flutter with 4:1 conduction, then an 11-beat run with 2:1 conduction

Atrial FlutterAtrial Flutter InterventionsInterventions The treatment goals are the same as those for The treatment goals are the same as those for

supraventricular tachycardia (SVT). The nurse administers supraventricular tachycardia (SVT). The nurse administers oxygen and prescribed drugs such as ibutilide (Covert), oxygen and prescribed drugs such as ibutilide (Covert), amiodarone (Cordarone), diltiazem (Cardizem), and amiodarone (Cordarone), diltiazem (Cardizem), and verapamil (Calan, Isoptin) to slow the rapid ventricular verapamil (Calan, Isoptin) to slow the rapid ventricular response. response.

Quinidine or procainamide (Pronestyl) must not be Quinidine or procainamide (Pronestyl) must not be administered unless one of the above agents has slowed administered unless one of the above agents has slowed the ventricular response. Both drugs slow the atrial rate the ventricular response. Both drugs slow the atrial rate and may increase AV conduction, which could cause a 1:1 and may increase AV conduction, which could cause a 1:1 conduction with an increase in ventricular rate and conduction with an increase in ventricular rate and hemodynamic deterioration.hemodynamic deterioration.

The nurse helps the physician to attempt rapid atrial The nurse helps the physician to attempt rapid atrial overdrive pacing or to achieve cardioversion if the client is overdrive pacing or to achieve cardioversion if the client is hemodynamically compromised. If he or she fails to hemodynamically compromised. If he or she fails to respond to these therapies, radiofrequency catheter respond to these therapies, radiofrequency catheter ablation may be necessaryablation may be necessary

Atrial FibrillationAtrial Fibrillation

Multiple, rapid impulses from Multiple, rapid impulses from many atrial foci at a rate of 350 many atrial foci at a rate of 350 to 600 times per minuteto 600 times per minute

Atrial FibrillationAtrial Fibrillation Clinical manifestations Clinical manifestations The nurse assesses the client for the presence of a pulse The nurse assesses the client for the presence of a pulse

deficit, fatigue, weakness, shortness of breath, distended deficit, fatigue, weakness, shortness of breath, distended neck veins, dizziness, decreased exercise tolerance, neck veins, dizziness, decreased exercise tolerance, anxiety, syncope, palpitations, chest discomfort or pain, anxiety, syncope, palpitations, chest discomfort or pain, and hypotension.and hypotension.

The client is also at risk for pulmonary embolism. The nurse The client is also at risk for pulmonary embolism. The nurse should assess for shortness of breath, chest pain, should assess for shortness of breath, chest pain, hemoptysis, and a feeling of impending doom.hemoptysis, and a feeling of impending doom.

The client is at risk for systemic emboli, particularly an The client is at risk for systemic emboli, particularly an embolic stroke. Changes in mentation, speech, sensory embolic stroke. Changes in mentation, speech, sensory function, and motor function are particularly noted. function, and motor function are particularly noted.

The nurse also assesses pulses, urine output, back pain, The nurse also assesses pulses, urine output, back pain, and complaints of gastrointestinal (GI) disturbances. and complaints of gastrointestinal (GI) disturbances.

Any of these symptoms should be reported to the health Any of these symptoms should be reported to the health care provider immediately. care provider immediately.

Atrial FibrillationAtrial Fibrillation Interventions Interventions Treatment is the same as for atrial flutter. In Treatment is the same as for atrial flutter. In

addition, the nurse may administer addition, the nurse may administer anticoagulants, such as heparin, enoxaparin anticoagulants, such as heparin, enoxaparin (Lovenox), and sodium warfarin, as prescribed (Lovenox), and sodium warfarin, as prescribed by the physician for clients considered to be at by the physician for clients considered to be at high risk for emboli. high risk for emboli.

Before elective cardioversion, the nurse must Before elective cardioversion, the nurse must initiate anticoagulation therapy for 4 to 5 initiate anticoagulation therapy for 4 to 5 weeks as prescribed to prevent a weeks as prescribed to prevent a thromboembolic event if the rhythm is thromboembolic event if the rhythm is successfully convertedsuccessfully converted

Junctional Dysrhythmias Junctional Dysrhythmias

Atrioventricular cells generating Atrioventricular cells generating electrical impulses at a rate of electrical impulses at a rate of 40 to 60 beats/min40 to 60 beats/min

These rhythms are most These rhythms are most commonly transient, and clients commonly transient, and clients usually remain hemodynamically usually remain hemodynamically stable.stable.

Idioventricular RhythmIdioventricular Rhythm Also called ventricular escape rhythm: ventricular nodal Also called ventricular escape rhythm: ventricular nodal

cells pace the ventricles. P waves are independent of the cells pace the ventricles. P waves are independent of the QRS complex (AV dissociation).QRS complex (AV dissociation).

Clinical manifestations - because idioventricular Clinical manifestations - because idioventricular pacemakers are unstable, unreliable, and slow, the client is pacemakers are unstable, unreliable, and slow, the client is hypotensive and in shock or, most typically, is pulseless hypotensive and in shock or, most typically, is pulseless and therefore in cardiac arrest. The nurse assesses the and therefore in cardiac arrest. The nurse assesses the client's airway, breathing, circulation, level of client's airway, breathing, circulation, level of consciousness, and pupillary responseconsciousness, and pupillary response

Interventions - usually, idioventricular rhythms require Interventions - usually, idioventricular rhythms require immediate resuscitation measures, unless there is a do-not-immediate resuscitation measures, unless there is a do-not-resuscitate (DNR) order. The nurse initiates resuscitate (DNR) order. The nurse initiates cardiopulmonary resuscitation (CPR) and summons cardiopulmonary resuscitation (CPR) and summons assistance. The team may initiate advanced cardiac life assistance. The team may initiate advanced cardiac life support (ACLS) measures, including epinephrine support (ACLS) measures, including epinephrine administration, intravascular volume replacement, and administration, intravascular volume replacement, and other measures. The physician may attempt pacemaker other measures. The physician may attempt pacemaker therapy or discontinue resuscitation effortstherapy or discontinue resuscitation efforts

Idioventricular rhythm with a rate of 35 beats/min

Premature Ventricular ComplexesPremature Ventricular Complexes

A result of increased irritability of A result of increased irritability of ventricular cells: early ventricular ventricular cells: early ventricular complexes followed by a pausecomplexes followed by a pause

Ventricular dysrhythmias. A, Normal sinus rhythm with unifocal premature ventricular complexes (PVCs). B, Normal sinus

rhythm with multifocal PVCs (one negative and the other positive). C, Normal sinus rhythm with three consecutive PVCs

(nonsustained ventricular tachycardia) and another unifocal PVC

Premature Ventricular ComplexesPremature Ventricular Complexes

Clinical manifestationsClinical manifestations The client may be asymptomatic or may experience The client may be asymptomatic or may experience

palpitations or chest discomfort caused by increased stroke palpitations or chest discomfort caused by increased stroke volume of the normal beat after the pause. Peripheral pulses volume of the normal beat after the pause. Peripheral pulses may be diminished or absent with the PVCs themselves may be diminished or absent with the PVCs themselves because the decreased stroke volume of the premature because the decreased stroke volume of the premature beats may decrease peripheral perfusion. Since other beats may decrease peripheral perfusion. Since other rhythms also cause widened QRS complexes, it is essential rhythms also cause widened QRS complexes, it is essential that the nurse assess whether the premature complexes that the nurse assess whether the premature complexes perfuse. This is done by palpating the carotid, brachial, or perfuse. This is done by palpating the carotid, brachial, or femoral arteries while observing the monitor for widened femoral arteries while observing the monitor for widened complexes, or auscultating for the apical heart sounds. With complexes, or auscultating for the apical heart sounds. With acute myocardial infarction, PVCs may be considered acute myocardial infarction, PVCs may be considered warning dysrhythmias, possibly heralding the onset of warning dysrhythmias, possibly heralding the onset of ventricular tachycardia (VT) or ventricular fibrillation (VF). ventricular tachycardia (VT) or ventricular fibrillation (VF). For a client with chest discomfort or pain, the nurse reports For a client with chest discomfort or pain, the nurse reports to the physician whether PVCs increase in frequency, are to the physician whether PVCs increase in frequency, are multiform, are R-on-T phenomena, or occur in runs of VTmultiform, are R-on-T phenomena, or occur in runs of VT

Premature Ventricular ComplexesPremature Ventricular Complexes

InterventionsInterventions If there is no underlying heart disease, PVCs are If there is no underlying heart disease, PVCs are

not usually treated other than by eliminating any not usually treated other than by eliminating any contributing cause (e.g., caffeine, stress). contributing cause (e.g., caffeine, stress).

With acute myocardial ischemia or infarction, the With acute myocardial ischemia or infarction, the nurse treats significant PVCs by administering nurse treats significant PVCs by administering oxygen and lidocaine as prescribed. oxygen and lidocaine as prescribed.

The nurse may administer other drugs as ordered, The nurse may administer other drugs as ordered, including procainamide (Pronestyl), bretylium including procainamide (Pronestyl), bretylium (Bretylol, Bretylate), magnesium sulfate, (Bretylol, Bretylate), magnesium sulfate, propranolol (Inderal, Apo-Propranolol), quinidine, propranolol (Inderal, Apo-Propranolol), quinidine, and mexiletine (Mexitil). and mexiletine (Mexitil).

Potassium is administered as ordered for Potassium is administered as ordered for replacement therapy if hypokalemia is the causereplacement therapy if hypokalemia is the cause

Ventricular TachycardiaVentricular Tachycardia Also called V tach: repetitive firing of an Also called V tach: repetitive firing of an

irritable ventricular ectopic focus, usually at irritable ventricular ectopic focus, usually at a rate of 140 to 180 beats/mina rate of 140 to 180 beats/min

Clinical manifestationsClinical manifestations Slower rates are better tolerated. Clients Slower rates are better tolerated. Clients

may be hemodynamically compromised if may be hemodynamically compromised if the cardiac output decreases because of the the cardiac output decreases because of the shortened ventricular filling time and loss of shortened ventricular filling time and loss of the atrial kick. In some clients, VT causes the atrial kick. In some clients, VT causes cardiac arrest. The nurse assesses the cardiac arrest. The nurse assesses the client's airway, breathing, circulation, level client's airway, breathing, circulation, level of consciousness, and pupillary responseof consciousness, and pupillary response

Ventricular dysrhythmias. Sustained ventricular tachycardia at a rate of 166 beats/min

Ventricular TachycardiaVentricular Tachycardia InterventionsInterventions For the stable client with sustained VT, the nurse administers For the stable client with sustained VT, the nurse administers

oxygen and confirms the rhythm via a 12-lead electrocardiogram oxygen and confirms the rhythm via a 12-lead electrocardiogram (ECG). Amiodarone, procainamide, or magnesium sulfate may be (ECG). Amiodarone, procainamide, or magnesium sulfate may be given. given.

The physician may prescribe an oral antidysrhythmic agent, such The physician may prescribe an oral antidysrhythmic agent, such as procainamide (Procan SR), mexiletine (Mexitil), or sotalol as procainamide (Procan SR), mexiletine (Mexitil), or sotalol (Betapace, Sotacor).(Betapace, Sotacor).

For the client with unstable VT, the nurse assists the physician in For the client with unstable VT, the nurse assists the physician in attempting emergency cardioversion followed by oxygen and attempting emergency cardioversion followed by oxygen and antidysrhythmic therapy. The nurse may instruct the client to antidysrhythmic therapy. The nurse may instruct the client to perform cough cardiopulmonary resuscitation (CPR) if prescribed, perform cough cardiopulmonary resuscitation (CPR) if prescribed, telling him or her to inhale deeply and cough hard every 1 to 3 telling him or her to inhale deeply and cough hard every 1 to 3 seconds. The physician may attempt rapid atrial or ventricular seconds. The physician may attempt rapid atrial or ventricular overdrive pacing if the VT is related to a significant overdrive pacing if the VT is related to a significant bradydysrhythmia.bradydysrhythmia.

A precordial thump is sometimes successful in terminating VT, at A precordial thump is sometimes successful in terminating VT, at least transiently. The physician or the nurse may administer a least transiently. The physician or the nurse may administer a precordial thump to a client with unstable VT only if a defibrillator precordial thump to a client with unstable VT only if a defibrillator and pacemaker are immediately available.and pacemaker are immediately available.

Ventricular TachycardiaVentricular Tachycardia With pulseless VT, the physician or nurse or other health care With pulseless VT, the physician or nurse or other health care

provider must provider must immediately immediately defibrillate the client or initiate CPR defibrillate the client or initiate CPR and defibrillate as soon as possible. A precordial thump may be and defibrillate as soon as possible. A precordial thump may be administered initially, although it is frequently not successful in administered initially, although it is frequently not successful in terminating VT. If the client remains pulseless, the nurse or other terminating VT. If the client remains pulseless, the nurse or other health care provider must resume CPR and full resuscitative health care provider must resume CPR and full resuscitative measures following defibrillation. This includes airway measures following defibrillation. This includes airway management and administration of oxygen, epinephrine, and management and administration of oxygen, epinephrine, and antidysrhythmic therapy with amiodarone, magnesium sulfate, antidysrhythmic therapy with amiodarone, magnesium sulfate, and procainamide.and procainamide.

If the rhythm has been successfully converted, attention is given If the rhythm has been successfully converted, attention is given to treating reversible causes of VT, such as myocardialto treating reversible causes of VT, such as myocardial ischemia, ischemia, hypokalemia, and hypomagnesemia. The nurse ensures that hypokalemia, and hypomagnesemia. The nurse ensures that oxygen therapy and antidysrhythmic agent administration are oxygen therapy and antidysrhythmic agent administration are continued, and the client is closely monitored for premature continued, and the client is closely monitored for premature ventricular complexes (PVCs) and the recurrence of VT. ventricular complexes (PVCs) and the recurrence of VT.

Some forms of VT may require surgical intervention, such as Some forms of VT may require surgical intervention, such as coronary artery bypass graft (CABG) surgery, implantation of a coronary artery bypass graft (CABG) surgery, implantation of a cardioverter/defibrillator, aneurysmectomy, encircling endocardial cardioverter/defibrillator, aneurysmectomy, encircling endocardial ventriculotomy, cryosurgery, or endocardial resection ventriculotomy, cryosurgery, or endocardial resection

Ventricular Fibrillation Ventricular Fibrillation Also called V fib: a result of electrical chaos Also called V fib: a result of electrical chaos

in the ventriclesin the ventricles Clinical manifestationsClinical manifestations On initiation of VF, the client becomes faint, On initiation of VF, the client becomes faint,

immediately loses consciousness, and immediately loses consciousness, and becomes pulseless and apneic. There is no becomes pulseless and apneic. There is no blood pressure, and heart sounds are absent. blood pressure, and heart sounds are absent. Respiratory and metabolic acidosis develop. Respiratory and metabolic acidosis develop. Seizures may occur. Within minutes, the Seizures may occur. Within minutes, the pupils become fixed and dilated, and the skin pupils become fixed and dilated, and the skin becomes cold and mottled. Death ensues becomes cold and mottled. Death ensues without prompt restoration of an organized without prompt restoration of an organized rhythm and cardiac outputrhythm and cardiac output

Ventricular FibrillationVentricular Fibrillation InterventionsInterventions The goals of treatment are to terminate VF promptly and The goals of treatment are to terminate VF promptly and

convert it to an organized rhythm. The physician or the ACLS convert it to an organized rhythm. The physician or the ACLS nurse or other health care provider must immediately nurse or other health care provider must immediately defibrillate the client to accomplish this goal. This is the defibrillate the client to accomplish this goal. This is the management priority, and the ACLS algorithm for VF must be management priority, and the ACLS algorithm for VF must be followed. If a defibrillator is not readily available, a precordial followed. If a defibrillator is not readily available, a precordial thump may be delivered. CPR must be continued until the thump may be delivered. CPR must be continued until the defibrillator arrives.defibrillator arrives.

If the VF does not terminate after three rapid successive shocks If the VF does not terminate after three rapid successive shocks of increasing energy, the nurse and resuscitation team resume of increasing energy, the nurse and resuscitation team resume CPR and provide airway management. They also administer CPR and provide airway management. They also administer oxygen and antidysrhythmic therapy with epinephrine, oxygen and antidysrhythmic therapy with epinephrine, amiodarone, procainamide (Pronestyl), lidocaine, and amiodarone, procainamide (Pronestyl), lidocaine, and magnesium sulfate, along with attempting defibrillation magnesium sulfate, along with attempting defibrillation frequently. frequently.

If VF is successfully converted to an organized rhythm, the If VF is successfully converted to an organized rhythm, the nurse continues supportive therapy and assists the physician in nurse continues supportive therapy and assists the physician in treating potential causes of VF and preventing its recurrence.treating potential causes of VF and preventing its recurrence.

Ventricular AsystoleVentricular Asystole

Also called ventricular standstill: Also called ventricular standstill: complete absence of any ventricular complete absence of any ventricular rhythmrhythm

Clinical manifestationsClinical manifestations Clients are in full cardiac arrest with Clients are in full cardiac arrest with

loss of consciousness and absence of loss of consciousness and absence of pulse, respirations, and blood pulse, respirations, and blood pressure. Ventricular asystole is often pressure. Ventricular asystole is often unresponsive to resuscitation unresponsive to resuscitation measures and fatalmeasures and fatal

Ventricular asystole with one idioventricular complex

Ventricular AsystoleVentricular Asystole InterventionsInterventions The goal of treatment is to restore cardiac electrical activity. The goal of treatment is to restore cardiac electrical activity. The nurse or other health care provider initiates CPR The nurse or other health care provider initiates CPR

immediately and summons assistance. immediately and summons assistance. Another ECG lead is assessed to ensure that the rhythm is Another ECG lead is assessed to ensure that the rhythm is

asystole and not fine VF, which warrants immediate asystole and not fine VF, which warrants immediate defibrillation. When in doubt, the client should be defibrillation. When in doubt, the client should be defibrillated. defibrillated.

The nurse and resuscitation team manage the airway and The nurse and resuscitation team manage the airway and administer oxygen, epinephrine, and atropine. administer oxygen, epinephrine, and atropine.

The nurse assists the physician with the initiation of The nurse assists the physician with the initiation of noninvasive pacing or invasive transvenous or epicardial noninvasive pacing or invasive transvenous or epicardial pacing, although pacemaker therapy is generally not pacing, although pacemaker therapy is generally not effective. effective.

An isoproterenol infusion may also be tried. An isoproterenol infusion may also be tried. The prognosis for clients with asystole is poorThe prognosis for clients with asystole is poor

Atrioventricular BlocksAtrioventricular Blocks

Atrioventricular blocks are Atrioventricular blocks are differentiated by their PR differentiated by their PR interval.interval.– First-degree atrioventricular blockFirst-degree atrioventricular block– Second-degree atrioventricular Second-degree atrioventricular

blockblock– Third-degree atrioventricular blockThird-degree atrioventricular block

First-Degree Atrioventricular First-Degree Atrioventricular BlockBlock

PR interval greater than 0.20 secondPR interval greater than 0.20 second Clinical manifestationsClinical manifestations First-degree AV block has no hemodynamic consequences First-degree AV block has no hemodynamic consequences

and produces no symptoms. Any symptoms are the result and produces no symptoms. Any symptoms are the result of the underlying rhythm (e.g., sinus bradycardia). First-of the underlying rhythm (e.g., sinus bradycardia). First-degree AV block may be insignificant and transient or may degree AV block may be insignificant and transient or may progress to more severe AV blocksprogress to more severe AV blocks

Interventions Interventions In the stable client, no treatment is needed. If the PR In the stable client, no treatment is needed. If the PR

interval is particularly long or is getting progressively interval is particularly long or is getting progressively longer, the nurse must notify the physician. If the first-longer, the nurse must notify the physician. If the first-degree AV block is due to drug therapy, the nurse must degree AV block is due to drug therapy, the nurse must withhold the offending drug and notify the physician. When withhold the offending drug and notify the physician. When first-degree AV block is associated with symptomatic first-degree AV block is associated with symptomatic bradycardia, oxygen and atropine are administered as bradycardia, oxygen and atropine are administered as prescribed to accelerate AV conductionprescribed to accelerate AV conduction

Normal sinus rhythm with first-degree AV block (PR interval, 0.36 second)

Second-Degree Atrioventricular Second-Degree Atrioventricular BlockBlock

Progressive prolongation of the PR interval, Progressive prolongation of the PR interval, followed by a dropped beat and a pause; each followed by a dropped beat and a pause; each group has one more P wave than QRS complexesgroup has one more P wave than QRS complexes

Clinical manifestationsClinical manifestations The client is usually asymptomatic if the The client is usually asymptomatic if the

frequency of dropped beats and the overall frequency of dropped beats and the overall ventricular rate do not decrease the cardiac ventricular rate do not decrease the cardiac output. If the ventricular rate is too slow, output. If the ventricular rate is too slow, decreasing the cardiac output, the client will have decreasing the cardiac output, the client will have symptoms of a symptomatic bradydysrhythmia. symptoms of a symptomatic bradydysrhythmia. This rhythm is usually transient and terminates This rhythm is usually transient and terminates spontaneouslyspontaneously

Second-degree AV block type I (Wenckebach AV) with an irregular rhythm, grouped beating, and progressive

prolongation of the PR interval until a P wave is completely blocked and not followed by a QRS complex

Second-Degree Atrioventricular Second-Degree Atrioventricular BlockBlock

InterventionsInterventions No intervention is required in the stable No intervention is required in the stable

client, because this rhythm rarely client, because this rhythm rarely progresses to a more severe block. In the progresses to a more severe block. In the symptomatic client, the nurse administers symptomatic client, the nurse administers oxygen and atropine as prescribed. If oxygen and atropine as prescribed. If atropine is not successful in speeding AV atropine is not successful in speeding AV nodal conduction time and increasing the nodal conduction time and increasing the heart rate, the nurse initiates pacemaker heart rate, the nurse initiates pacemaker therapy as ordered and notifies the therapy as ordered and notifies the physicianphysician

Second-Degree Heart Block Type II Second-Degree Heart Block Type II

Mobitz type II block is an Mobitz type II block is an infranodal block occurring below infranodal block occurring below the bundle of His.the bundle of His.

Constant block in one of the Constant block in one of the bundle branches results in a bundle branches results in a wide QRS complex and dropped wide QRS complex and dropped beats.beats.

Second-degree AV block type II (Mobitz II) with 2:1 conduction, a constant PR interval, and wide QRS complex

Second-Degree Heart Block Type IISecond-Degree Heart Block Type II

Clinical manifestationsClinical manifestations Symptoms depend on the frequency of dropped beats and Symptoms depend on the frequency of dropped beats and

the overall ventricular rate. If the cardiac output is the overall ventricular rate. If the cardiac output is inadequate, the client presents with a symptomatic inadequate, the client presents with a symptomatic bradydysrhythmia.bradydysrhythmia.

InterventionsInterventions In the asymptomatic client, the nurse may assist the In the asymptomatic client, the nurse may assist the

physician in initiating prophylactic pacing to avert the threat physician in initiating prophylactic pacing to avert the threat of sudden third-degree AV block. If slow ventricular rates are of sudden third-degree AV block. If slow ventricular rates are present, the nurse administers oxygen and at ropine as present, the nurse administers oxygen and at ropine as prescribed. Atropine is usually ineffective because it does prescribed. Atropine is usually ineffective because it does not reverse the infranodal block. An isoproterenol (Isuprel) not reverse the infranodal block. An isoproterenol (Isuprel) infusion may be administered with caution but may be infusion may be administered with caution but may be dangerous in adults with ischemic heart disease. dangerous in adults with ischemic heart disease. Noninvasive (external) or invasive pacing is preferred. A Noninvasive (external) or invasive pacing is preferred. A permanent pace maker may be required with recurrent permanent pace maker may be required with recurrent Mobitz type II blockMobitz type II block

Third-Degree Heart BlockThird-Degree Heart Block

Heart block is complete.Heart block is complete. None of the sinus impulses None of the sinus impulses

conducts to the ventricles.conducts to the ventricles.

Third-degree AV block (complete heart block) with regular atrial and ventricular rhythms, inconstant PR intervals (AV

dissociation), and a junctional es cape focus (normal QRS complexes) pacing the ventricles at a rate of 44 beats/min

Third-Degree Heart BlockThird-Degree Heart Block Clinical manifestationsClinical manifestations Depend on the overall ventricular rate and cardiac Depend on the overall ventricular rate and cardiac

output. Transient third-degree heart block may be output. Transient third-degree heart block may be well tolerated, particularly when the block is in the well tolerated, particularly when the block is in the AV node. If the block is infranodal, it may have AV node. If the block is infranodal, it may have serious hemodynamic consequences. If cerebral serious hemodynamic consequences. If cerebral perfusion is inadequate, clients may be confused and perfusion is inadequate, clients may be confused and lightheaded or may experience episodes of syncope lightheaded or may experience episodes of syncope with or without seizures (Stokes-Adams attacks). with or without seizures (Stokes-Adams attacks). Inadequate cardiac output may cause myocardial Inadequate cardiac output may cause myocardial ischemia or infarction, heart failure, or hypotension. ischemia or infarction, heart failure, or hypotension. Third-degree heart block may predispose to cardiac Third-degree heart block may predispose to cardiac arrest, causing VT, VF, or asystole. Therefore it is arrest, causing VT, VF, or asystole. Therefore it is regarded as a dangerous rhythmregarded as a dangerous rhythm

Third-Degree Heart BlockThird-Degree Heart Block InterventionsInterventions Third-degree AV block with a junctional escape pacemaker Third-degree AV block with a junctional escape pacemaker

is often transient and well tolerated. If the client is is often transient and well tolerated. If the client is symptomatic, the nurse administers oxygen and atropine as symptomatic, the nurse administers oxygen and atropine as prescribed. prescribed.

Clients with third-degree heart block with a ventricular Clients with third-degree heart block with a ventricular escape pacemaker are frequently symptomatic. The nurse escape pacemaker are frequently symptomatic. The nurse administers oxygen and assists the physician in initiating administers oxygen and assists the physician in initiating pacing to avert the threat of cardiac arrest. Atropine is pacing to avert the threat of cardiac arrest. Atropine is usually not successful in infranodal blocks with wide QRS usually not successful in infranodal blocks with wide QRS complexes. Cautious use of isoproterenol (Isuprel) infusions complexes. Cautious use of isoproterenol (Isuprel) infusions may be necessary as a temporary measure while awaiting may be necessary as a temporary measure while awaiting pacemaker therapy but is dangerous in clients with acute pacemaker therapy but is dangerous in clients with acute myocardial infarction. myocardial infarction.

Implantation of a permanent pacemaker may be required Implantation of a permanent pacemaker may be required for clients with recurrent third-degree infranodal blockfor clients with recurrent third-degree infranodal block

Bundle Branch Blocks Bundle Branch Blocks Conduction delay or block within one of the two main Conduction delay or block within one of the two main

bundle branches below the bifurcation of the bundle of Hisbundle branches below the bifurcation of the bundle of His

Clinical manifestationsClinical manifestations There are no clinical manifestations specifically related to There are no clinical manifestations specifically related to

bundle branch block. The nurse must notify the physician bundle branch block. The nurse must notify the physician when a new bundle branch block develops, especially in the when a new bundle branch block develops, especially in the client with an acute myocardial infarction. The conduction client with an acute myocardial infarction. The conduction disorder may deteriorate to a more significant block disorder may deteriorate to a more significant block requiring pacemaker therapyrequiring pacemaker therapy

InterventionsInterventions No interventions are specifically related to bundle branch No interventions are specifically related to bundle branch

block. The client is assessed during alterations in heart rate block. The client is assessed during alterations in heart rate for symptoms of hemodynamic compromise, which are for symptoms of hemodynamic compromise, which are reported to the physician. The nurse ensures that the client reported to the physician. The nurse ensures that the client is resting and has adequate ventilation and oxygenationis resting and has adequate ventilation and oxygenation

Normal sinus rhythm with bundle branch block (wide QRS complexes measuring 0.12 second)

Decreased Cardiac Output and Decreased Cardiac Output and Ineffective Tissue PerfusionIneffective Tissue Perfusion

Interventions include:Interventions include:– Cardiac careCardiac care– Nonsurgical managementNonsurgical management– Drug therapyDrug therapy

Vaughn-Williams classificationVaughn-Williams classification Other antidysrhythmic drugsOther antidysrhythmic drugs Emergency cardiac drugsEmergency cardiac drugs

Nonsurgical Nonsurgical ManagementManagement

Vagal maneuversVagal maneuvers Carotid sinus massageCarotid sinus massage Valsalva maneuversValsalva maneuvers

Temporary PacingTemporary Pacing

Modes of pacingModes of pacing– Synchronous pacingSynchronous pacing– Asynchronous pacingAsynchronous pacing

Noninvasive temporary pacingNoninvasive temporary pacing Invasive Temporary PacingInvasive Temporary Pacing

Treatments Treatments

Cardiopulmonary resuscitationCardiopulmonary resuscitation Advanced cardiac life supportAdvanced cardiac life support Cardioversion: synchronized Cardioversion: synchronized

countershock that may be used for countershock that may be used for emergent hemodynamically unstable emergent hemodynamically unstable ventricular or supraventricular ventricular or supraventricular tachydysrhythmias or electively for tachydysrhythmias or electively for stable tachydysrhythmias resistant stable tachydysrhythmias resistant to medical therapiesto medical therapies

Defibrillation Defibrillation

Asynchronous countershock Asynchronous countershock depolarizes a critical mass of depolarizes a critical mass of myocardium simultaneously to myocardium simultaneously to stop the re-entry circuit and stop the re-entry circuit and allow the sinus node to regain allow the sinus node to regain control of the heart.control of the heart.

Maintain a patent airway.Maintain a patent airway. Administer oxygen.Administer oxygen.

(Continued)(Continued)

DefibrillationDefibrillation (Continued)(Continued)

Assess vital signs and level of Assess vital signs and level of consciousness.consciousness.

Administer antidysrhythmic Administer antidysrhythmic drugs.drugs.

Monitor for dysrhythmias .Monitor for dysrhythmias . Assess for burns, emotional Assess for burns, emotional

support, documentation.support, documentation.

Other Therapies Other Therapies Automatic external defibrillationAutomatic external defibrillation Radiofrequency catheter Radiofrequency catheter

ablationablation Surgical procedures:Surgical procedures:

– Permanent pacemakerPermanent pacemaker– Coronary artery bypass graftingCoronary artery bypass grafting– AneurysmectomyAneurysmectomy– Insertion of implantable Insertion of implantable

cardioverter/defribillatorcardioverter/defribillator– Open-chest cardiac massageOpen-chest cardiac massage