sudden cardiac death - cardiovascular nursing education ... · pdf filecarol jacobson rn, mn 1...

Carol Jacobson RN, MN www.cardionursing.com 1

Relax and Learn at the Farm

2013

Sudden Cardiac Death

Channelopathies

Abnormalities in ion channels that control entry of ions into

or out of the cardiac cell – especially Na+ and K+

Genetic channelopathies

Long QT Syndrome

Short QT Syndrome

Brugada Syndrome

Catecholaminergic Polymorphic VT

Arrhythmogenic Right Ventricular Cardiomyopathy


Na+

Ca++

K+ Na+ entering cell

is responsible for

depolarization

K+ leaving cell is

responsible for

repolarization

3 Na+ out

2 K+ in

Na+

Ca++

K+

Cardiac Action Potential


SO . . . .

Anything that causes the cell to remain positive

inside longer than normal delays its repolarization

back to the resting state and prolongs repolarization

and the QT interval

Drugs that block potassium channels: some

antiarrhythmics, antidepressants, many others

Genetic abnormalities of the potassium channel

Genetic abnormalities of the sodium channel

Channelopathies

Linked to sudden infant death syndrome and SCD in

young people

Suspect and rule out in children or teenagers with

unexplained syncope or cardiac arrest

Primary presenting symptom in most people is syncope –

which can resolve or result in SCD

SCD is often the first symptom of Brugada syndrome and

hypertrophic cardiomyopathy


Congenital Long QT Syndromes

Hereditary gene mutations that affect sodium or

potassium ion channels on cardiac cell membranes

Associated with increased risk of SCD due to

ventricular arrhythmias (TdP)

13 different genes identified so far – labeled LQT1

through LQT13

Congenital LQTS

LQT1 and LQT2 account for about 90% of

congenital cases

Affect potassium channels and cause reduction in

repolarizing potassium current

LQT3 accounts for about 5% - 8%

Affects sodium channels and causes an increase in sodium

current entering cell

Other types are very rare


QT interval prolongation is a critical part of diagnosis

LQT1: wide, broad-based T waves

LQT2: low amplitude, often notched T waves

LQT3: long ST segment and tall, peaked T waves

Triggers for Torsades in Congenital LQTS

LQT1

Exercise: exaggerated QT prolongation during exercise

Swimming or diving: initiates diving reflex and slows HR

LQT2

Emotions

Sudden noise (alarm clock, phone)

Pause dependent TdP common with LQT2 but not others

LQT3

On awakening

During sleep


2 week old QTc during 1:1 conduction = 414 ms

Same 2 week old during 2:1 block

QTc = 550ms


2 year old with 2:1 block

QTc = 695 ms

13 year old girl arrested at a slumber party

Rhythm strips from AED after medics arrived


13 year old girl arrested at a slumber party

QTc = 576 ms

Management of Congenital LQTS

Preventive Measures

Avoid loud noises and activities that trigger adrenergic

surges

Remove or blunt alarm clocks, phones, other loud devices

Avoid places where sudden noise or stress could occur: roller

coasters, loud music

No competitive sports

Avoid QT prolonging drugs

Prevent electrolyte depletion


Management of Congenital LQTS

Beta blockers (antiadrenergic effects)

Mainstay of therapy for congenital LQTS

Especially effective in LQT1 patients, least effective in LQT3

Dual chamber pacing at a rate to shorten QT

ICD

Patients who have survived cardiac arrest

Patients who continue to have cardiac events (VT, syncope,

aborted SCD) on beta blockers

High-risk LQT2 and LQT3 patients benefit most

Clinical Implications of a

Short QT Interval

First described in 2000

Inherited channelopathy involving gene mutations

that affect potassium channels

5 types identified so far

Characterized by:

Constantly short QT interval <320 ms

Associated with atrial fibrillation

Syncopal episodes

SCD


Other potential causes of a short QT interval should

be ruled out:

Hyperkalemia, hypercalcemia

Hyperthermia

Acidosis

Digitalis use also shortens the QT

Determination of QT interval in SQTS:

HR should be < 100

Bazett formula not recommended: it provides a longer

QTc than is really present

SQTS

ECG characteristics

QT <320 ms

Tall, peaked T waves in precordial leads

No or very short ST segment

Presentation ranges from asymptomatic to syncope

to SCD

30% incidence of atrial fib, occurs at all ages

Management is ICD implantation


21 year old woman with cardiac arrest

Defibrillated and brought to ED

Lab work normal

Causes of short QT ruled out

Went in to VF again, resuscitation was unsuccessful

QT = 240 ms

Brugada Syndrome

Inherited channelopathy involving mutations of the SCN5A

gene that participates in regulation of cardiac sodium channels

Usually no structural heart disease

Seen worldwide but is most prevalent in southeast Asia (very

common in Thailand)

Occurs most often in men (8:1 male to female ratio)

Usually manifests in 3rd or 4th decade of life but can be seen in

children

Associated with high incidence of SCD due to lethal

ventricular arrhythmias

Responsible for at least 4% of all sudden deaths and at least 20% of

sudden deaths in patients with structurally normal hearts


Brugada Syndrome

ECG Criteria

RBBB pattern in V1 to V2/V3

Often no S waves in lateral leads as with RBBB

J point elevation in V1 to V2/V3

ST elevation in V1 to V2/V3

QT interval sometimes mildly prolonged

ECG can be transiently normal

Brugada Syndrome

Clinical Presentation

Dizzy spells, lightheadedness

Seizures

Syncope or near syncope

Palpitations

Sudden Cardiac Death – often the first “symptom”

Symptoms usually occur during rest and at night, but 15%

of patients have symptoms during exercise

Fever can trigger the ECG changes and arrhythmia episodes

(cardiac arrest)

Cocaine abuse and other drugs can bring out ECG changes

All related to life

threatening ventricular

arrhythmias


3 ECG Patterns of Brugada

Type 1: “Coved type” - elevated ST segment (≥2 mm) descends with an upward

convexity to an inverted T wave.

Type 2: “Saddle-back type”- high takeoff ST elevation > 2 mm followed by ST

elevation > 1 mm and a positive or biphasic T wave.

Type 3: ST elevation < 1 mm with coved or saddle-back pattern

Diagnostic Criteria for Brugada Syndrome

Type 1 ECG pattern in more than one right chest lead (V1-V3)

and at least one of the following:

Documented VF or polymorphic VT

Family history of sudden cardiac death at <45 years

Type 1 ST segment elevation in family members

EPS inducibility of VT/VF

Unexplained syncope suggestive of a tachyarrhythmia

Nocturnal agonal respiration

Type 2 or 3 pattern that converts to Type 1 with sodium

channel blocking drugs plus one of above criteria


Brugada Syndrome

19 year old male with history of dizzy spells. Type 3 ECG pattern

Young man with history of “seizures”

Type 1 ECG pattern

Brugada Syndrome


Treatment of Brugada

ICD

Class I recommendation for SCD survivors

Class IIa recommendation for BS patients with syncope or

documented VT

No proven pharmacologic treatments for preventing

SCD

Quinidine has been effective

No consensus on how to treat asymptomatic patients

Catecholaminergic Polymorphic VT

Occurs in absence of structural heart disease and

typically begins in adolescence or childhood

Mutations in two genes have been identified

Patients typically present with life-threatening VT or

ventricular fibrillation (VF) occurring during emotional

or physical stress

Syncope is often the first manifestation


CPVT

ECG in sinus rhythm is usually normal (no long QT)

Two types of polymorphic VTs have been described: "Typical" polymorphic VT with continuously varying QRS

morphology (similar to ischemia related PVT in patients with normal QT interval)

Bidirectional ventricular tachycardia with alternans of the QRS complexes

Management: Cardioversion if sustained and unstable

IV beta blockers

Amiodarone as long as QT is not prolonged

ICD

Catecholaminergic VT


Arrhythmogenic Right Ventricular

Cardiomyopathy (ARVC)

An inherited heart-muscle disease that is a major cause

of sudden death in young people and athletes.

Estimated to occur in 1:2000 to 1:5000 people

Affects men more often than women (3:1 ratio)

Characterized by

Replacement of myocardium in the RV by fibro-fatty tissue

Ventricular arrhythmias

The left ventricle can also be involved.


Presentation of ARVC

• Adolescents or young people with

palpitations, syncope, or aborted

sudden death.

• ECG changes:

– T wave inversion in V1–V3

– Epsilon waves at end of QRS in V1-V3

– PVCs of left bundle branch block

morphology (>500/24h)

• VT of left bundle branch block

morphology

VT with LBBB pattern, often occurs with exercise


Treatment

There is no cure – can progress to heart failure

Main Goal: Prevention of SCD ICD therapy is indicated for secondary prevention after prior

cardiac arrest and in patients with hemodynamically unstable VT

Antiarrhythmic drugs Not equivalent to ICD

Adjunctive therapy with amiodarone or sotalol for frequent VT and ICD shocks

Beta blockers may be helpful

Activity Restriction No competitive sports (VT often occurs with exercise)

Avoid high-intensity noncompetitive sports (basketball, tennis, etc)


Hypertrophic Cardiomyopathy

Autosomal dominant genetic disease of the cardiac

sarcomere, caused by mutations in one of several genes that

encode components of the contractile proteins (actin, myosin,

troponins, others) – “disease of the sarcomeres”:

Diastole

Systole

Characterized by left ventricular

hypertrophy of various

morphologies

Depending on the site and extent of hypertrophy, patients can

develop one or more of the following abnormalities: LV outflow tract obstruction

Diastolic dysfunction

Myocardial ischemia

Mitral regurgitation

Morphologies of HCM

Asymmetrical septal hypertrophy with

outflow tract obstruction

Midcavity hypertrophy

(cavity obstruction)

Free wall hypertrophy (unusual)

Severe concentric hypertrophy

Biventricular hypertrophy

Symmetric hypertrophy


Most common hereditary cardiac disease: 1:500-1000 of general population

Causes 60-80% of cases are genetic

Acquired as result of HTN or aortic stenosis

SCD often first manifestation of the disease Occurs in a minority of HCM patients - rate of about 1% per

year.

HCM is the most common cause of SCD in young athletes (about one third of SCD events)

Diagnosed by the presence of: Unexplained cardiac hypertrophy (hypertrophy in the absence of

an increased load, as occurs with aortic stenosis or HTN)

Small left ventricular cavity size

Diastolic dysfunction

Preserved or increased LV systolic function

Sudden Cardiac Death in HCM A minority of patients with HCM are judged to be

at increased risk for SCD, with a rate of about 1%

per year

SCD is most often due to ventricular tachy-

arrhythmias, usually in asymptomatic patients <35

years of age

Most patients with HCM are asymptomatic, and most

will achieve a normal life expectancy

Risk stratification for SCD should be done in all patients,

regardless of whether symptoms are present


Risk Factors for SCD in HCM

Prior history of VF, SCD, or sustained VT

Family history of SCD

Syncope

Nonsustained VT

More important in younger patients (<30 years of age)

Exercise-induced NSVT has been found to have independent association with SCD

LV Wall Thickness >30 mm

Abnormal blood pressure response during exercise

Failure to increase by at least 20 mm Hg or a drop of at least 20 mm Hg during exercise

Some studies have found higher rates of SCD among patients with outflow tract obstruction (resting gradients >30 mm Hg)

ICDs are the only effective means of preventing

SCD and prolonging life in patients with HCM

Among patients who received an ICD due to a prior

episode of cardiac arrest or sustained ventricular

arrhythmia (secondary prevention ICD), the annualized

rate of subsequent appropriate ICD discharge was 10%

per year.

Patients with primary prevention ICDs placed on the

basis of 1 or more of the risk markers for SCD

experienced appropriate ICD therapy at a rate of 4% per

year.


Commotio Cordis

VF and SCD secondary to relatively innocent

chest wall impact Common causes of sudden cardiac death in young athletes

National Commotio Cordis Registry was established in the

mid 1990s and contains over 200 confirmed cases Young people are most commonly affected Mean age of registry cases was 15 years

Only 9% of reported cases occurred in someone older than 25 years of

age.

95 percent of reported cases have been in males.

75 percent of cases have occurred during athletics (50% during

competitive sports, 25% during recreational sports).

Most cases occurred in sports with blunt projectiles (baseball,

lacrosse, hockey) and/or more physical contact (football, hockey).

Mechanism of SCD in Commotio Cordis

Primary electrical event with VF occurring on chest wall impact Increased dispersion of ventricular repolarization caused by the blow appears

to underlie VF The potassium channel is likely activated by the chest blow and contributes to

the development of VF

Timing of impact The most important variable appears to be the timing of chest trauma within

the cardiac cycle. Only impacts occurring during a 20 to 40 ms window on the upslope of the T-

wave (early ventricular repolarization) will cause VF.

Location of impact Only impacts occurring directly over the heart result in VF

Velocity of impact As projectile velocity increases up to 40 mph, the incidence of VF increases to

70% At impact velocities greater than 40 mph, the probability of VF decreases (but

frequency of myocardial rupture and cardiac contusion increases)


Most commonly occurs in sports in which a small

hard dense object becomes a projectile, such as

baseball, lacrosse and hockey.

Larger balls and non-spherical objects less likely to cause VF.

Survival is poor - survival of only 25% in all patients

in the registry.

Survival is improving over time, with 58% survival in casses

reported between 2006-2012

Due to increased availability of AED, activation of EMS, and

bystander CPR

Management with standard BLS and ACLS care

sudden cardiac death - cardiovascular nursing education ... · pdf filecarol jacobson rn, mn 1...

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