Heart I, II and III

Question 1

What structure is primarily responsible for the division of the truncus arteriosus into the great arteries?

Answer 1

The aorticopulmonary septum functions to divide the truncus arteriosus and bulbus cordis into the aorta and pulmonary trunk.

The septum secundum forms an incomplete separation between the 2 atria.

The septum primum divides the atrium into right and left halves.

The bulbar septum is derived from the bulbus cordis and will give rise to the interventricular septum inf. to the aorticopulmonary septum, eventually fusing with it.

Question 2

A 2-year old child is seen in the pediatric cardiology unit for a congenital heart condition. Which of the following conditions occurs most often?

Answer 2

VSDs account for 25% of congenital heart defects. The most common of these are defects in the membranous portion of the interventricular septum (membranous VSDs)

Question 3

A patient has transposition of the great arteries. If untreated for more than 4 months, it is fatal. Which structure must remain patent so that the infant can survive until surgical correction of the malformation?

Answer 3

In a case of transposition of the great arteries, oxygenated blood travels from the left ventricle into the pulmonary trunk, where it will eventually reach the lungs. In contrast, the aorta would be carrying deoxygenated blood into the system circulation. A PDA acts as a shunt between the aorta and pulmonary trunk, allowing oxygenated and deoxygenated blood to mix and allow some oxygenated blood to reach the tissues.

Question 4

A newborn is diagnosed with pulmonary artery stenosis, overriding of the aorta, VSD and hypertrophy of the right ventricle. Which condition is characterized by these signs?

Answer 4

Tetralogy of Fallot is characterized by 4 cardiac defects, “PROVe that you have Tetralogy of Fallot”

1. Pulmonary stenosis
2. Right ventricular hypertrophy
3. Overriding aorta
4. VSD

Question 5

A newborn is diagnosed with pulmonary artery stenosis, overriding of the aorta, VSD and hypertrophy of the right ventricle. Which embrylogic mechanism is responsible for this cluster of anomalies?

Answer 5

Superior malalignment of the subpulmonary infundibulum causes stenosis of the pulmonary trunk. This leads to the 4 symptoms associated with ToF.

A defect in formation of the aorticopulmonary septum is characteristic of transposition of the great arteries.

An endocardial cushion defect is associated with membranous VSDs.

Question 6

A radiologist notes that contrast medium released into the arch of the aorta is visible immediately in the left pulmonary artery. What is the explanation for this finding?

Answer 6

The ductus arteriosus is an embryologic structure that acts as a communication between the pulmonary trunk and the aorta. It it remains patent, the injected contrast medium would flow from the aorta through this communication and into the pulmonary artery.

An ASD is a communication between the atria.

Mitral stenosis is a narrowing of the AV valve between the left atrium and the left ventricle.

The ductus venosus transports blood from the left umbilical vein to the IVC, bypassing the liver.

Question 7

A patient presents with a clinically signficant atrial septal defect (ASD). The ASD usually results from incomplete closure of which structure?

Answer 7

An ASD is a communication between the right and left atria. In the formation of the partition between the 2 atria, the opening in foramen secundum, aka the foramen ovale, typically closes at birth. It it remains patent, an ASD will result.

Question 8

A patient has episodes of fatigue and dyspnea. Ultrasound reveals an ASD located at the opening of the sup. vena cava. Which type of ASDs are characteristic for this description?

Answer 8

Sinus venosus ASDs occur close to the entry of the SVC in the superior portion of the interatrial septum.

Ostium secundum ASDs are located near the fossa ovale and encompass both septum primum and septum secundum defects.

An ostium primum defect is a less common form of ASD and is associated with endocardial cushion defects because the septum primum fails to fuse with the endocardial cushions, resulting in a patent foramen primum.

Question 9

A newborn presents with cyanosis and tachypnea. Examination reveals totally anomalous pulmonary connections. What embryologic event is responsible for this malformation?

Answer 9

The right horn of the sinus venosus has 2 division: one develops into the sinus venarum (smooth interior aspect of right atrial wall) and the other half develops into the pulmonary veins. Abnormal septation of the sinus venosus can lead to inappropriate pulmonary connections.

Abnormal dev. of the left sinus horn would present with abnormalities in the coronary sinus.

Incorrect dev. of the setpum secundum can result in an ASD.

Question 10

A newborn presents with severe cyanosis. Examination reveals a right-to-left shunt. What condition would produce this shunt?

Answer 10

A common truncus arteriosus results from failure of separation of the pulmonary trunk and aorta. Without proper perfusion of the child by oxygenated blood, severe cyanosis will result.

Question 11

A patient presents with tachycardia. What is the location of the preganglionic neural cell bodies involved in increasing the heart rate?

Answer 11

The lateral horns, or intermediolateral cell columns, contain the cell bodies of preganglionic neurons of the symp. system. Spinal cord segments T1-T4 are often associated with the upper limbs and thoracic organs.

Question 12

A patient is diagnosed with a possible myocardial infarction. Which nerves carry pain from the heart to the CNS?

Answer 12

The cardiopulmonary splanchnic (or thoracic visceral) nerves are responsible for carrying the cardiac symp. efferent fibers from the symp. ganglia to the thoracic viscera and afferent fibers for pain from these organs.

Question 13

A patient complains of retrosternal pain that radiates to the left shoulder. The pain is relieved by leaning forward. Auscultation reveals a pericardial friction rub, leading to pericarditis. Which nerve is responsible for radiating pain to the shoulder?

Answer 13

Pericarditis is an inflammation of the pericardium and often causes a pericardial friction rub. Because the phrenic nerve is solely responsible for innervation of the pericardium, it would transmit the pain fibers radiating from the pericardial friction rub.

Question 14

A patient complains of chest pain and pain radiating to his left arm. Which nerve is responsible for the radiation of pain to the arm during myocardial infarction?

Answer 14

The intercostobrachial nerve is the lateral cutaneous branch of the second intercostal nerve. It serves a cutaneous function both in the thoracic wall and medial aspect of the arm.

Question 15

During examination, a slight rhythmic pulsation on the chest walll at the left 5th intercostal space is noted in the midclavicular line. What part of the heart is responsible for this pulsation?

Answer 15

The apex of the heart is located in the 5th intercostal space, about 3.5 inches to the left of the sternum. When this area of the heart is palpated, any pulsations would be generated by throbbing of the apex of the heart against the thoracic wall.

This is also the location for performing auscultation of the mitral valve, not associated with palpation.

Question 16

A patient has mitral valve prolapse. Auscultation of this valve is best performed at which location?

Answer 16

The left 5th intercostal space, just below the left nipple, is the best location the listen to the mitral valve.

Question 17

Angiography reveals total blockage of the circumflex artery near its origin from the left coronary artery. When this artery is exposed to perform a bypass procedure, what accompanying vein must be proctected?

Answer 17

The great cardiac vein (ant. interventricular vein) takes a pathway initially beside the ant. interventricular coronary artery aka left anterior descending (LAD), finally terminating in the coronary sinus.

Question 18

A patient is to undergo a bypass operation. The artery of primary concern is the vessel that supplies much of the left ventricle and the right and left bundle branches of the cardiac conduction system. Which artery is the surgeon concerned with?

Answer 18

The atnerior interventricular artery (left ant. interventricular artery, LAD) supplies the right and left ventricles and anterior 2/3 of the IV septum.

The right marginal artery supplies the right ventricle and apex of heart.

The left coronary circumflex a. supplies the left atrium and left ventricle. It courses posteriorly in, or near to, the coronary sulcus and supplies the posterior portion of the left ventricle and left atrium.

The artery to the SA node is a branch of the r. coronary a. and does not supply the left ventricle.

Question 19

A patient has significant occlusion in his right coronary artery, just distal to the right sinus of the aortic valve. His collateral cardiac circulation is minimal. Assuming the patient is right coronary dominant, which artery would be most likely to have normal blood flow?

Answer 19

The anterior interventricular artery (LAD) arises from the left coronary a. If there is occlusion in the r. coronary a. the anterior interventricular a. will still have normal blood flow.

The right marginal a. branches from the r. coronary a.

The SA nodal a. is supplied by the r. coronary a. in right coronary dominant patients.

Question 20

ECG examination provides evidence of severe MI of the lower part of the muscular interventricular septum. The function of which valve will be most affected?

Answer 20

The interventricular septum is intimately involved with the tricuspid valve on the right side, via the muscular connections of the septomarginal trabeculum (moderator band) to the anterior papillary muscle.

Question 21

After opertaion, an infant develops severe arrhythmias affecting both ventricles. Which part of the conduction tissue is most likely injured?

Answer 21

The AV bundle of His is a collection of specialized cardiac muscle cells (Purkinje fibers) that carry electrical activity to the right and left bundle branches. Since both ventricles are affected, this is the logical site of injury.

An injury either to the r. or l. bundle branches would affect only one ventricle.

Question 22

Angiography in a patient is performed and shows that the artery supplying the upper portion of the anterior r. ventricular free wall is occluded. Which artery is occluded?

Answer 22

The artery of the conus is given off from the r. coronary a. and winds around the conus arteriosus. The conus region is the superior part of the r. ventricle that tapers into a cone (infundibulum) where the pulmonary valve leads into the pulmonary trunk. This conus artery supplies the upper portion of the anterior r. ventricle.

Question 23

A patient dies unexpectedly in his sleep. A portion of the conduction tissue that penetrates the right fibrous trigone had become necrotic, which lead to a fatal arrhythmia developing. What part of the conduction tissue was interrupted?

Answer 23

The atrioventricular bundle of His arises from the atrioventricular node and passes through the right fibrous trigone. The right fibrous trigone is a dense area of connective tissue that interconnects the mitral, tricuspid and aortic valve rings.

Question 24

A patient underwent blunt trauma to her sternum. Which cardiac structure is most likely injured?

Answer 24

The sternocostal surface of the heart consists mostly of the right ventricle.

However, during a cardiac tamponade, the right atrium would most likely be compressed due to the low pressure within the atrium.

Question 25

ECG reveals MI in the anterior 2/3 of the interventricular septum and left anterior ventricular wall. The ECG also revealed a left bundle branch block. Which artery is occluded?

Answer 25

The tissues affected in this case (interventricular septum and anterior ventricular wall) are mostly supplied by the prox. portion of the left anterior interventricular artery.

If the circumflex a. were blocked, the l. atrium and l. ventricle would be affected (assuming right coronary dominance).

If the r. coronary a. were occluded (assuming r. coronary dominance), it would affect the r. atrium, the SA and AV nodes, part of the post. l. ventricle and the post. part of the interventricular septum.

Question 26

A patient undergoes surgery to correct an interventricular septal defect. Which structure is the most crucial to protect during the opening of the right atrium?

Answer 26

The crista terminalis is a muscular ridge that runs from the opening of the SVC to the IVC. This ridge provides the path taken by the posterior internodal pathway between the SA and AV nodes. The crista also provides the origin of the pectinate muscles of the right auricle.

Question 27

A surgeon can place her fingers in the transverse pericardial sinus. This allows the surgeon to easily place a vascular clamp upon which vessels?

Answer 27

A finger passing through the transverse pericardial sinus passes directly behind the 2 great arteries exiting the heart, allowing the surgeon to easily place a vascular clamp upon the pulmonary trunk and ascending aorta.

Question 28

Arteriography reveals total blockage of the posterior descending interventricular artery. Which vessel accompanies this artery?

Answer 28

The middle cardiac veins run parallel with the posterior interventricular (posterior descending) a. and drains directly into the coronary sinus.

The great cardiac vein parallels the ant. interventricular a.

The small cardiac veins pass parallel with the r. marginal a.

Question 29

(70). If the posterior interventricular branch in a patient arises from the right coronary artery, which part of the myocardium will most likely have its blood supply reduced if the circumflex branch of the left coronary artery becomes occluded from plaque?

Answer 29

The left coronary artery bifurcates into the anterior interventricular artery (LAD) and the coronary circumflex branch. The circumflex branch gives off the left marginal branch, which supplies the lateral wall of the left ventricle.

The anterior part of the interventricular septum is supplied by the LAD.

The diaphragmatic surface of the r. ventricle is supplied by the posterior descending artery and the right marginal (branch of the r. coronary a.)

Question 30

(71). Angiography reveals that the right coronary artery is blocked just distal to the origin of the right marginal artery in a right coronary dominant circulation. Which structure would be affected?

Answer 30

The AV node is most commonly supplied by a branch of the r. coronary artery. This branch arises at the crux of the heart (the point of junction of all 4 cardiac chambers posteriorly); this is the lcoation of the occlusion.

Question 31

(72). A patient is diagnosed with mitral valve stenosis. The first heart sound is abnormally loud. Which heart valves are responsible for this?

Answer 31

The first heart sound is caused by the closure of the tricuspid and mitral valves. The second heart sound is caused by the closure of the aortic and pulmonary valves.

Question 32

(75). A surgeon explores the oblique pericardial sinus. Which of the following is not directly palpable with the tips of the fingers?

Answer 32

The SVC empties into the right atrium on the superior aspect of the heart. It is not directly palpable from the oblique sinus.

The oblique sinus is a cul-de-sac providing access to the IVC, posterior wall of the left atrium, right atrium and the right and left pulmonary veins.

Question 33

(76). A patient was stabbed in the chest. Examination reveals she has cardiac tamponade. What is found during physical examination?

Answer 33

Cardiac tamponade is charcterized by 3 D’s:

1. diminished/distant heart sounds
2. distension of jugular vein
3. decreased BP

Bleeding into the pericardial cavity muffles the heart sounds because of the increased distance between the chest wall and the heart, leading to “distant” heart sounds.