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Chest, Heart and Lungs

Chest

Mediastinum

• Superior mediastinum:

• Contents:

• thymus gland

• veins – tend to be anterior & towards the right.

• arteries – behind the vein and to the left.

Thymus gland• In the superior and anterior mediastinum, beneath the manubrium

& upper sternum, extends laterally beneath the upper 4 costal cartilage.

• rises into the base of neck under the sternohyoid & sternothyroid muscles.

• lies anterior to the aorta, brachiocephalic vein and fibrous pericardium.

• varies in size: • *at birth it is 10 – 15 gm. • *Puberty it is 30 – 40 gms • *late adult it regress by involution and fatty atrophy to <10 gms.• Very important lymphoid organ associated with immunologic

recognition.• Thymomectomy is done for myasthenia gravis • ( autoimmune disorder with neuromuscular junctions ).

Brachiocephalic veins:

• right & the longer diagonal left unite to form the SVC.

• SVC receives the azygos veins before emptying into the right atrium.

Ascending aorta

• emerges from the pericardial sac between the SVC and pulmonary trunk.

• Runs superiorly and towards the right before arching posteriorly as the aortic arch.

Aortic arch

• “aortic knob” , a radiographic landmark at the (L) mediastinum.

• Branches are:– left and right coronary arteries

• brachiocephalic artery ( r side only) forms the RCA

• and RSA.– LCCA = sometimes arise from BCA in blacks.– LSubclavian Artery

POSTERIOR Mediastinum

• lies behind the pericardial sac.

• From Vertebra level T4 to T12.

• Bounded by the:• mediastinal pleura on the sides• diaphragm below.

• posterior, continous with the superior

mediastinum.

Structures of posterior mediastinum

• Descending aorta• ligamentum arteriosum = from the ductus

arteriosus.• Intercostal arteries = supply the thoracic wall,

anastomose with anterior intercostal branches of internal thoracic arteries(mammary).

• Bronchial arteries = supply the bronchial tree.• Esophageal arteries = supply the midportion of

esophagus

Structures of posterior mediastinum…..

• Esophagus• 25 – 30 cm long, cm. shorter in females.• Lies anterior to the prevertebral fascia,

midline behind the trachea.• Inferior to the tracheal bifurcation.• Thoracic duct• Thoracic lymph nodes• Venous drainage• Thoracic sympathetic trunk• Vagus nerve

Heart Anatomy

• The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist. By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times. In fact, each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood.

The Heart Anatomy

The Heart Anatomy….

• Your heart is located between your lungs in the middle of your chest, behind and slightly to the left of your breastbone (sternum).

• A double-layered membrane called the pericardium surrounds your heart like a sac.

• The outer layer of the pericardium surrounds the roots of your heart's major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body.

• The inner layer of the pericardium is attached to the heart muscle.

• A coating of fluid separates the two layers of membrane, letting the heart move as it beats, yet still be attached to your body.

The Heart Anatomy….

• The heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.

Four types of valves regulate blood flow through your heart

• The tricuspid valve regulates blood flow between the right atrium and right ventricle.  

• The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.  

• The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.  

• The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of your body.

The Conduction System

The Conduction System

• Electrical impulses from your heart muscle (the myocardium) cause your heart to contract. This electrical signal begins in the sinoatrial (SA) node, located at the top of the right atrium. The SA node is sometimes called the heart's "natural pacemaker." An electrical impulse from this natural pacemaker travels through the muscle fibers of the atria and ventricles, causing them to contract. Although the SA node sends electrical impulses at a certain rate, your heart rate may still change depending on physical demands, stress, or hormonal factors.

Conduction system….

• Electrical impulses from your heart muscle (the myocardium) cause your heart to beat (contract). This electrical signal begins in the sinoatrial (SA) node, located at the top of the right atrium. The SA node is sometimes called the heart's "natural pacemaker." When an electrical impulse is released from this natural pacemaker, it causes the atria to contract

The Conduction System

• When the SA node sends an electrical impulse, that impulse first travels through the heart's upper chambers (the atria). It then passes through a small group of cells called the atrioventricular (AV) node. The AV node checks the impulse and sends it along a track called the bundle of His. The bundle of His divides into a right bundle branch and a left bundle branch, which lead to your heart's lower chambers (the ventricles).

The Conduction System

• Sometimes the electrical impulse cannot travel throughout the heart because part of the heart's conduction system is "blocked." If an impulse is blocked as it travels through the bundle branches, you are said to have bundle branch block.

What causes bundle branch block?

• For the left and right ventricles to contract at the same time, an electrical impulse must travel down the right and left bundle branches at the same speed. If there is a block in one of these branches, the electrical impulse must travel to the ventricle by a different route.

Bundle branch block, cause…..

• When this happens, the rate and rhythm of your heartbeat are not affected, but the impulse is slowed. Your ventricle will still contract, but it will take longer because of the slowed impulse. This slowed impulse causes one ventricle to contract a fraction of a second slower than the other.

• The medical terms for bundle branch block are derived from which branch is affected. If the block is located in the right bundle branch, it is called right bundle branch block. If the block is located in the left bundle branch, it is called left bundle branch block.

• The block can be caused by coronary artery disease, cardiomyopathy, or valve disease. Right bundle branch block may also occur in a healthy heart.

What are the symptoms of bundle branch block?

• If there is nothing else wrong with your heart, you probably will not feel any symptoms of bundle branch block. In fact, some people may have bundle branch block for years and never know they have the condition. In people who do have symptoms, they may faint (syncope) or feel as if they are going to faint (presyncope).

So why should we worry about bundle branch block?

• Because it can be a warning sign of other, more serious heart conditions. For example, it might mean that a small part of your heart is not getting enough oxygen-rich blood. Also, researchers have found that people who have left bundle branch block may be at greater risk for heart disease than are people who do not have the condition.

How is bundle branch block diagnosed?

• Doctors can use an electrocardiogram (EKG or ECG) machine to record the electrical impulses of your heart. Bundle branch block shows up on the EKG tracing. The electrical patterns recorded by the EKG machine can even show your doctor whether the block is located in the right or left bundle branch.

How is bundle branch block treated?

• In most cases, bundle branch block does not need treatment. But patients who have bundle branch block along with another heart condition may need treatment. For example, if bundle branch block develops during a heart attack, you may need a pacemaker. After a heart attack, your heart is fragile, and bundle branch block may cause a very slow heart rhythm (bradycardia). A pacemaker will help regulate the heart's rhythm after a heart attack.

How is bundle branch block treated…….

• For patients with both bundle branch block and dilated cardiomyopathy, a new type of pacing called cardiac resynchronization treatment (CRT) may be used. Normally, pacemakers pace only one of the lower heart chambers (the ventricles) at a time. But CRT re-coordinates the beating of the two ventricles by pacing them at the same time.

Arrhythmia

• Your heart pumps nearly 5 quarts of blood through your body every minute. Even while you are sitting still, your heart beats (expands and contracts) 60 to 80 times each minute. These heartbeats are triggered by electrical impulses that begin in your heart's natural pacemaker, called the sinoatrial node (SA node). The SA node is a group of cells located at the top of your heart's upper right chamber (the right atrium).

Arrhythmia …..

• Any irregularity in your heart's natural rhythm is called an arrhythmia. Almost everyone's heart skips or flutters at one time or another, and these mild, one-time palpitations are harmless. But there are about 4 million Americans who have recurrent arrhythmias, and these people should be under the care of a doctor.

Categories of Arrhythmia

• Arrhythmias can be divided into two categories: ventricular and supraventricular.

• Ventricular arrhythmias happen in the heart's two lower chambers, called the ventricles.

• Supraventricular arrhythmias happen in the structures above the ventricles, mainly the atria, which are the heart's two upper chambers.

Arrhythmias …..

• Arrhythmias are further defined by the speed of the heartbeats:

• Bradycardia = A very slow heart rate, means the heart rate is less than 60 beats per minute.

• Tachycardia is a very fast heart rate, meaning the heart beats faster than 100 beats per minute.

• Fibrillation, the most serious form of arrhythmia, is fast, uncoordinated beats, which are contractions of individual heart-muscle fibers.

What is heart block?

• Heart block happens when the SA node's electrical signal cannot travel to the heart's lower chambers (the ventricles).

What causes an arrhythmia?

• Many factors can cause your heart to beat irregularly. Some people are born with arrhythmias, meaning the condition is congenital. Some medical conditions, including many types of heart disease and high blood pressure, may be factors. Also, stress, caffeine, smoking, alcohol, and some over-the-counter cough and cold medicines can affect the pattern of your heartbeat.

What are the symptoms of arrhythmias?

• Whether you have symptoms and what those symptoms feel like depend on the health of your heart and the type of arrhythmia you have. Symptoms also depend on how severe the arrhythmia is, how often it happens, and how long it lasts. Some arrhythmias do not produce any warning signs. Contrary to popular belief, heart palpitations do not always mean that you have an arrhythmia.

Symptoms of arrhythmias….

• Symptoms of bradycardia• You may feel tired, short of breath, dizzy, or

faint.• Symptoms of tachycardia• Your heartbeat may feel like a strong pulse in

your neck, or a fluttering, racing• beat in your chest.

• You may feel chest discomfort, weak, short of breath, faint, sweaty, or dizzy.

How is an arrhythmia diagnosed?

• The following techniques are used to diagnose arrhythmias.

• A standard electrocardiogram (ECG or EKG) is the best test for diagnosing arrhythmia. This test helps doctors analyze the electrical currents of your heart and determine the type of arrhythmia you have. 

• Holter monitoring gets a non-stop reading of your heart rate and rhythm over a 24-hour period (or longer). You wear a recording device (the Holter monitor), which is connected to small metal disks called electrodes that are placed on your chest. With certain types of monitors, you can push a "record" button to capture a rhythm when you feel symptoms

How is an arrhythmia diagnosed?

• Electrophysiology studies (EPS) are usually done in a cardiac catheterization laboratory. A long, thin tube called a catheter is inserted into an artery in your leg and guided to your heart. A map of electrical impulses from your heart is sent through the catheter. This map helps doctors find out what kind of arrhythmia you have and where it starts. During the study, doctors can give you controlled electrical impulses to show how your heart reacts. Medicines may also be tested at this time to see which will stop the arrhythmia. Once the electrical pathways causing the arrhythmia are found, radio waves can be sent through the catheter to destroy them

How is arrhythmia treated?

• Anti-arrhythmic medicines, including digitalis, beta-blockers, and calcium channel blockers, are often the first approach taken for treating arrhythmia. Other treatments include percutaneous (catheter) interventions, implantable devices, and surgery (for severe cases).

Conduction system….

• The signal then passes through the atrioventricular (AV) node. The AV node checks the signal and sends it through the muscle fibers of the ventricles, causing them to contract. The SA node sends electrical impulses at a certain rate, but your heart rate may still change depending on physical demands, stress, or hormonal factors.

How is arrhythmia treated…..

• Ventricular tachycardia and ventricular fibrillation can be treated by an implantable cardioverter defibrillator (ICD). This is a device that applies electric impulses or, if needed, a shock to restore a normal heartbeat. The device's power source is implanted in a pouch beneath the skin of your chest or the area above your stomach and connected to patches placed on your heart. Newer implantable devices are inserted through blood vessels, which means that you do not need open-chest surgery. 

• An electronic pacemaker is used in some cases of slow heart rate. Smaller than a matchbox, the pacemaker is surgically implanted near the bone below your neck (the collarbone). The pacemaker's batteries supply the electrical energy that acts like your heart's natural pacemaker.

arrhythmia treated…

• Radiofrequency ablation is a procedure that uses a catheter and a device for mapping the electrical pathways of the heart. After you are given medicine to relax you, a catheter is inserted into a vein and guided to your heart, where doctors use high-frequency radio waves to destroy (ablate

arrhythmia treated…

• A technique called cryoablation can then be used to eliminate tissue with a cold probe and destroy the "misfiring" cells. 

• Maze surgery may be recommended if you have atrial fibrillation that has not responded to medicines or electrical shock (cardioversion therapy) or to pulmonary vein ablation (a procedure similar to radiofrequency ablation). Surgeons create a number of incisions in the atrium to block the erratic electrical impulses that cause atrial fibrillation. 

• Ventricular resection involves a surgeon removing the area in the heart's muscle where the arrhythmia starts.

arrhythmia treated…

• In other cases, no treatment is needed. Most people with an arrhythmia lead normal, active lifestyles. Often, certain lifestyle changes, such as avoiding caffeine (found in coffee, tea, soft drinks, chocolate, and some over-the-counter pain medicines) or avoiding alcohol, are enough to stop the arrhythmia.

Categories of Arrhythmias

• Arrhythmias are generally divided into two categories: ventricular and supraventricular.

• Ventricular arrhythmias occur in the lower chambers of the heart, called the ventricles.

• Supraventricular arrhythmias occur in the area above the ventricles, usually in the upper chambers of the heart, called the atria. The irregular beats can either be too slow (bradycardia) or too fast (tachycardia).

Bradycardia

Bradycardia

• Bradycardia is a very slow heart rate of less than 60 beats per minute. It happens when the electrical impulse that signals the heart to contract is not formed in your heart's natural pacemaker, the sinoatrial node (SA node), or is not sent to the heart's lower chambers (the ventricles) through the proper channels.

Bradycardia…..

• Bradycardia is a very slow heart rate of less than 60 beats per minute. It happens when the electrical impulse that signals the heart to contract is not formed in your heart's natural pacemaker, the sinoatrial node (SA node), or is not sent to the heart's lower chambers (the ventricles) through the proper channels.

Bradycardia….

• most often affects elderly people, but it may affect even the very young. It may be caused by one of two sources:

• 1. The central nervous system does not signal that the heart needs to pump more, or

• 2. the SA node may be damaged. This damage might be related to heart disease, aging, inherited or congenital defects, or it might be caused by certain medicines—including those used to control arrhythmias and high blood pressure.

Tachycardia

• Tachycardia is a very fast heart rate of more than 100 beats per minute. The many forms of tachycardia depend on where the fast heart rate begins. If it begins in the ventricles, it is called ventricular tachycardia. If it begins above the ventricles, it is called supraventricular tachycardia.

Ventricular Arrhythmias

• Ventricular Tachycardia• Ventricular tachycardia is a condition in which

the SA node no longer controls the beating of the ventricles. Instead, other areas along the lower electrical pathway take over the pacemaking role. Since the new signal does not move through your heart muscle along the regular route, the heart muscle does not beat normally. Your heartbeat quickens, and you feel as if your heart is "skipping beats." This rhythm may cause severe shortness of breath, dizziness, or fainting (syncope).

Ventricular Fibrillation• Ventricular Fibrillation• The most serious arrhythmia is ventricular fibrillation, which is an

uncontrolled, irregular beat. Instead of one misplaced beat from the ventricles, you may have several impulses that begin at the same time from different locations—all telling the heart to beat. The result is a much faster, chaotic heartbeat that sometimes reaches 300 beats a minute. This chaotic heartbeat means very little blood is pumped from the heart to the brain and body and can result in fainting. Medical attention is needed right away. If cardiopulmonary resuscitation (CPR) can be started, or if electrical energy is used to "shock" the heart back to a normal rhythm, then the heart may not be too damaged. About 220,000 deaths from heart attacks each year are thought to be caused by ventricular fibrillation. People who have heart disease or a history of heart attack have the highest risk of ventricular fibrillation.

Premature Ventricular Contractions

• A less serious type of ventricular arrhythmia is a premature ventricular contraction (PVC). As the name suggests, the condition happens when the ventricles contract too soon, out of sequence with the normal heartbeat. PVCs (sometimes called PVB for premature ventricular beat) generally are not a cause for alarm and often do not need treatment. But if you have heart disease or a history of ventricular tachycardia, PVCs can cause a more serious arrhythmia. Although most PVCs happen quickly and without warning, they can also happen in response to caffeine, which is found in coffee, tea, sodas, and chocolate. Some kinds of over-the-counter cough and cold medicines may also cause PVCs.

Supraventricular Arrhythmias

• Supraventricular arrhythmias happen in the upper chambers of the heart. Generally, supraventricular or "atrial arrhythmias" are not as serious as ventricular arrhythmias. Sometimes, they do not even require treatment. Like PVCs, atrial arrhythmias can happen in response to a number of things, including tobacco, alcohol, caffeine, and cough and cold medicines. The disorder also may result from rheumatic heart disease or an overactive thyroid gland (hyperthyroidism).

Supraventricular Tachycardia…..

• Supraventricular tachycardia is a rapid, regular heart rate where the heart beats more than 150 times per minute in the atria. Unlike other types of arrhythmias, supraventricular tachycardia does not start in the SA node.

Atrial Fibrillation

• Atrial fibrillation is a fast, irregular rhythm where single muscle fibers in your heart twitch or contract. According to the National Institutes of Health (NIH), about 2.2 million Americans have atrial fibrillation. It is a main cause of stroke, especially among elderly people. Atrial fibrillation may cause blood to pool in the heart's upper chambers. The pooled blood can lead to the formation of clumps of blood called blood clots. A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery). About 15% of strokes happen in people with atrial fibrillation.

Atrial fibrillation….

• Atrial fibrillation is a fast, irregular rhythm where single muscle fibers in your heart twitch or contract. According to the National Institutes of Health (NIH), about 2.2 million Americans have atrial fibrillation. It is a main cause of stroke, especially among elderly people. Atrial fibrillation may cause blood to pool in the heart's upper chambers. The pooled blood can lead to the formation of clumps of blood called blood clots. A stroke can occur if a blood clot travels from the heart and blocks a smaller artery in the brain (a cerebral artery). About 15% of strokes happen in people with atrial fibrillation.

Wolff-Parkinson-White Syndrome

• Wolff-Parkinson-White (WPW) syndrome is a group of abnormalities caused by extra muscle pathways between the atria and the ventricles. The pathways cause the electrical signals to arrive at the ventricles too soon, and the signals are sent back to the atria. The result is a very fast heart rate. People with this syndrome may feel dizzy, have chest palpitations, or have episodes of fainting.

Atrial Flutter

• Atrial flutter happens when the atria beat very fast, causing the ventricles to beat inefficiently as well.

Premature Supraventricular Contractions

• Also called "premature atrial contractions" (PACs), they happen when the atria contract too soon, causing the heart to beat out of sequence.

Heart Block

• Heart block takes place when the SA node sends its electrical signal properly, but the signal is not sent through the atrioventricular (AV) node or lower electrical pathways as quickly as it should be. The condition is most often caused by aging or by the swelling or scarring of the heart that sometimes results from coronary artery disease. There are several types of heart block, and they are named by their degree of severity.

Heart Block….

• First-degree heart block means that impulses are moving through the AV node too slowly. 

• Second-degree heart block means that impulses are traveling through the heart's atria but are delayed in the AV node. Because of this delay, the ventricles do not beat at the right moment. 

• Third-degree heart block means that no impulses are reaching the ventricles. To make up for this, the ventricles use their own "backup" pacemaker with its slower rate. Because a gap in time is likely to occur between the impulse from the atria and the impulse from the "backup" pacemaker in the ventricles, a person may faint. This is known as a Stokes-Adams attack. Third-degree heart block is very serious and can lead to heart failure or death.

Long Q-T Syndrome

• Long Q-T syndrome (LQTS) is a disorder of the heart's conduction system. The disorder affects a process called repolarization, which is the recharging of the heart after each heartbeat. Congenital LQTS is a rare disorder that is usually inherited (passed down through family members). In other cases, LQTS can be caused by certain medicines, or it can be the result of a stroke or some other neurologic disorder. LQTS can lead to an abnormal heart rhythm (arrhythmia); fainting or loss of consciousness (syncope); or even sudden death.

What causes LQTS?

• When your heart contracts, it sends out an electrical signal. The signal is produced by the flow of ions (potassium, sodium, and calcium) within the heart's cells. The ions flow in and out of the heart's cells through ion channels.

Torsade de pointes

• . A prolonged Q-T interval can increase your risk for a type of arrhythmia called torsade de pointes. When torsade de pointes occurs, your heart cannot pump enough oxygen-rich blood to the rest of your body, especially your brain.

• Torsade de pointes can also lead to ventricular fibrillation, a dangerous form of arrhythmia that causes rapid, uncoordinated contractions in the muscle fibers of the ventricles. With ventricular fibrillation, the heart cannot pump oxygen-rich blood to the rest of the body, which can lead to death.

Who is at risk for LQTS?

• Long Q-T syndrome can occur in people who seem very healthy. It usually affects children or young adults. You also have an increased risk for LQTS if other members of your family have the disorder.

• In some cases, medicines used to treat conditions such as arrhythmia (antiarrhythmics) or depression (antidepressants) may also put you at risk for LQTS.

What are the signs and symptoms of LQTS?

• People with LQTS may not have any signs or symptoms. For those who do have symptoms, fainting and arrhythmia are the most common. People with LQTS often show a prolonged Q-T interval during exercise, intense emotion (such as fright, anger, or pain), or as a reaction to a loud or startling noise.

• People with LQTS have usually had at least one episode of fainting by the time they are 10 years old. Others may just have 1 or 2 episodes of fainting as children, and then never have another episode again.

• In one type of inherited long Q-T syndrome, deafness is part of the disorder.

How is LQTS diagnosed?

• A standard electrocardiogram (EKG or ECG) is the best test for diagnosing LQTS. The EKG machine records your heart's electrical activity in waveforms, which can show a prolonged Q-T interval.  

• An exercise EKG, also known as a stress test, can show an abnormal Q-T interval that may otherwise be normal during a resting EKG.

•  • Holter monitoring gets a continuous reading of your heart rate and

rhythm over a 24-hour period (or longer). You wear a recording device (the Holter monitor), which is connected to small metal disks (called electrodes) on your chest. Doctors can then look at a printout of the recording to see if it shows a prolonged Q-T interval

Treatment for LQTS

• Lifestyle changes• If you are active in competitive sports, talk to

your doctor about how this may affect your condition. Often, once treatment in started, patients with LQTS can participate in recreational sports or other activities in moderation. If you have episodes of fainting while you exercise, you may want to think about exercising with a friend or a family member who can call for help if you need it.

Treatment for LQTS

• Medicines• Medicines called beta-blockers are the most

common type of medicine given to patients with LQTS. These medicines do not cure LQTS, but they have been shown to reduce the symptoms of LQTS for those who have them. Beta-blockers are also effective for patients who have been diagnosed with LQTS but do not have any symptoms. In these cases, doctors will most likely prescribe a beta-blocker to prevent the symptoms of LQTS.

Treatment for LQTS

• Surgery• When LQTS causes uncontrolled ventricular

fibrillation, you might need an implantable cardioverter defibrillator (ICD). An ICD is a device that sends an electric shock to your heart to restore a normal heartbeat. The device is placed under the skin of your chest or abdomen and is connected to leads, which are passed through your veins to your heart

Bundle Branch Block

• The heart has a natural "pacemaker" called the sinoatrial (SA) node. The SA node is a specialized group of cells at the top of your heart's upper-right chamber (the right atrium). Anywhere between 60 and 100 times a minute, the SA node sends an electrical impulse throughout your heart to cause it to beat (contract).

The Circulatory System

• Your heart and circulatory system make up your cardiovascular system. Your heart works as a pump that pushes blood to the organs, tissues, and cells of your body. Blood delivers oxygen and nutrients to every cell and removes the carbon dioxide and waste products made by those cells. Blood is carried from your heart to the rest of your body through a complex network of arteries, arterioles, and capillaries. Blood is returned to your heart through venules and veins. If all the vessels of this network in your body were laid end-to-end, they would extend for about 60,000 miles (more than 96,500 kilometers), which is far enough to circle the earth more than twice!

Coronary vessels..

Arteries:• Right coronary artery- originate from the right aortic

sinus beneath ® auricle to the coronary sulcus • Left coronary artery- from the (L) aortic sinus under left

auricle:• Anterior descending branch to A.Interv.S to apex• Circumflex coronary artery to posterior interv.sulcus

Coronary vessels…

Veins:• Coronary sinus, at post.coronary sulcus, receives most

veins and empties into the right atrium. • Great cardiac veins from apex, AIS, to coronary sinus• Small cardiac veins from right side coronary sulcus• Right marginal veins• Middle cardiac veins from apex to post. Long. Sulcus• Posterior veins of left ventricle on diaphragmatic surface• Oblique veins of left atrium from dorsum of atrium• Thebesian veins – opens directly to atrium

Pericardium

• Fibrous sac closed above by attachments to the great vessels.

• Serous smooth membrane with mesothelial layer lining the fibrous sac converting the heart surface into:

Visceral pericardium (pericardium)-heart surface

Parietal pericardium-lines the inner surface of the fibrous pericardium

Pericardium….

• Pericardial cavity- potential space between the parietal and visceral pericardium. The pericardial surface are in contact and is covered with a pericardial watery fluid to allow free movement during contraction.

• Mesocardium- the reflection of the epicardium along the great vessels and into the pericardail sac

Interior of the heart

• Right atrium – divided into parts by a ridge the crista terminalis.

Auricle – a blind pocket, lined by a parallel ridge,

pectinate muscle.

Sinus of vena cavae:

SVC, IVC, coronary sinus, small coronary

veins and atrioventricular orifice (R ventricle)

Interior of the heart

• Left atrium – has a smooth walled portion and small muscular auricle.

• 4 pulmonary veins open in the smooth walled portion.

Interior of the heart• Right ventricle – occupies

most of the sternocostal surface from coronary to anterior longitudinal sulci.

• Parts:a.conus arteriosus ( infundibulum)b. supraventricular crest-muscular ridge between venous outflow and inflow.c. ventricle proper

Trabeculae carneimoderator band(septomarginal)

papillary muscle d. chordae tendinae e. Interventricular septum* Left ventricle – small part of the

sternocostal/diaphragmatic surface

Valves of the heart

• Pulmonary valve (semilunar valve)– at the 3rd costosternal union left side

• Aortic valve ( semilunar valve) – at oppostie articulation of the 3rd costosternal joint

• Left atrioventricular (bicuspid or mitral)– opposite 4th costosternal articulation

• Right atrioventricular ( tricuspid ) – near sternal margin, opposite 4th interspace.

The Heartbeat

The Heartbeat

• A heartbeat is a two-part pumping action that takes about a second. As blood collects in the upper chambers (the right and left atria), the heart's natural pacemaker (the SA de) sends out an electrical signal that causes the atria to contract. This contraction pushes blood through the tricuspid and mitral valves into the resting lower chambers (the right and left ventricles). This part of the two-part pumping phase (the longer of the two) is called diastole.

The Heartbeat

• Systole…..• The second part of the pumping phase begins

when the ventricles are full of blood. The electrical signals from the SA node travel along a pathway of cells to the ventricles, causing them to contract. This is called systole. As the tricuspid and mitral valves shut tight to prevent a back flow of blood, the pulmonary and aortic valves are pushed open. While blood is pushed from the right ventricle into the lungs to pick up oxygen, oxygen-rich blood flows from the left ventricle to the heart and other parts of the body.

The Heartbeat

• After blood moves into the pulmonary artery and the aorta, the ventricles relax, and the pulmonary and aortic valves close. The lower pressure in the ventricles causes the tricuspid and mitral valves to open, and the cycle begins again. This series of contractions is repeated over and over again, increasing during times of exertion and decreasing while you are at rest. The heart normally beats about 60 to 80 times a minute when you are at rest, but this can vary. As you get older, your resting heart rate rises. Also, it is usually lower in people who are physically fit.

The Heartbeat

• Your heart does not work alone, though. Your brain tracks the conditions around you—climate, stress, and your level of physical activity—and adjusts your cardiovascular system to meet those needs.

• The human heart is a muscle designed to remain strong and reliable for a hundred years or longer. By reducing your risk factors for cardiovascular disease, you may help your heart stay healthy longer.

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