CV-Blood Week 1 Flashcards
The structure indicated by arrow 1 in the figure below (insert bottom right indicates level of the section) is which of the following vessels?
a. Brachiocephalic artery (trunk)
b. Left subclavian artery
c. Left common carotid artery
d. Right brachiocephalic vein
e. Superior vena cava
The structure indicated by arrow 1 in the figure below (insert bottom right indicates level of the section) is which of the following vessels?
a. Brachiocephalic artery (trunk) – arrow 2
b. Left subclavian artery – arrow 3 ( posterior and to the left of the left common carotid artery)
c. Left common carotid artery – in between arrow 2 and 3 (posterior to brachiocephalic artery)
d. Right brachiocephalic vein – correct answer, arrow 1
e. Superior vena cava – not seen at this level, notice that the right and left brachiocephalic veins (elongated structure immediately posterior to manubrium) are still separate
A 24-year old healthy medical student enrolls in a study assessing healthy parameters of human circulatory physiology. During the study, the blood oxygen content of the aorta and several other vessels is measured at rest. The greatest difference in these measurements will be between the aorta and which of the following blood vessels?
a. Internal jugular vein
b. Portal vein
c. Coronary sinus
d. Pulmonary artery
e. Pulmonary vein
A 24-year old healthy medical student enrolls in a study assessing healthy parameters of human circulatory physiology. During the study, the blood oxygen content of the aorta and several other vessels is measured at rest. The greatest difference in these measurements will be between the aorta and which of the following blood vessels?
a. Internal jugular vein
b. Portal vein
c. Coronary sinus
d. Pulmonary artery
e. Pulmonary vein
: Arterial blood supply to the cardiac muscle is provided by the right and left coronary arteries, which arise directly from the aortic root. Most cardiac venous blood drains into the right atrium via the coronary sinus.
Myocardial oxygen extraction is very high, the resting myocardium extract 60-75% of oxygen from blood, much higher than any other tissue or organ in the body. As a result, the cardiac venous blood in the coronary sinus is the most deoxygenated blood in the body, more deoxygenated than that carried by other veins like the internal jugular (A) or portal vein (B).
The pulmonary vein (E) carries oxygenated blood to the left atrium.
Deoxygenated systemic blood returning via the vena cava contains more oxygen than the coronary sinus venous blood. Pulmonary artery (D) contains an admixture of blood from the vena cava and coronary sinus, so its oxygen content is higher than pure coronary venous return.
A failure of the aortico-pulmonary septum to follow a spiral course results in which of the following conditions?
a. Common atrium
b. Persistent atrioventricular canal
c. Persistent truncus arteriosus
d. Tetralogy of Fallot
e. Transposition of the great vessels
A failure of the aortico-pulmonary septum to follow a spiral course results in which of the following conditions?
a. Common atrium – results from complete failure of the septum primum to form
b. Persistent atrioventricular canal – Results from failure of endocardial cushions to fuse and partition the AV canal into right and left components
c. Persistent truncus arteriosus – results from total failure of the aorticopulmonary ridges to develop in the first place and partition the outflow tract. Notice similarity but important distinction from E
d. Tetralogy of Fallot – primary malformation is unequal division of outflow tract, resulting in pulmonary stenosis. Other features are an interventricular septal defect, overriding aorta, RV hypertrophy.
e. Transposition of the great vessels – Correct answer. Occurs when the aorticopulmonary ridges fail to spiral as they divide the outflow tract into two channels. This produces two totally independent circulatory loops, with the RV feeding into the aorta and the LV feeding the pulmonary artery
During the first week of life, the umbilical vein can be catheterized and used for central venous pressure monitoring. The umbilical vein leads to which of the following vessels?
a. Descending aorta
b. Ductus arteriosus
c. Ductus venosus
d. Inferior vena cava
e. Umbilical arteries
During the first week of life, the umbilical vein can be catheterized and used for central venous pressure monitoring. The umbilical vein leads to which of the following vessels?
a. Descending aorta – in the fetus, distributes a mixture of oxygenated blood from IVC (via umbilical vein and ductus venosus) directed via foramen ovale (inferior vena cava -> right atrium -> patent foramen ovale -> left atrium -> left ventricle -> aorta) and deoxygenated blood from SVC (SVC -> RA -> RV - > pulmonary artery -> ductus arteriosus -> descending aorta)
b. Ductus arteriosus – allows bypass of deoxygenated blood from pulmonary trunk to descending aorta, due to high fetal pulmonary artery resistance
c. Ductus venosus – correct answer. In the fetus, umbilical vein connects directly to the ductus venosus, which bypasses the liver to bring oxygenated blood to the inferior vena cava (choice D)
d. Inferior vena cava – see explanation for C above
e. Umbilical arteries – carry blood from descending aorta for return to the placenta for oxygenation
A 4thyear medical student is learning to place a central line. She knows that the central venous catheter is inserted into the subclavian vein and subsequently threaded into the superior vena cava. To prepare for this procedure, she reviews the CT scan below, taken at the level indicated by the bottom right insert. What is the structure pointed to by arrow 3?
a. Ascending aorta
b. Azygous vein
c. Descending aorta
d. Superior vena cava
Note: Arrow 2 indicates the right bronchus.
A 4thyear medical student is learning to place a central line. She knows that the central venous catheter is inserted into the subclavian vein and subsequently threaded into the superior vena cava. To prepare for this procedure, she reviews the CT scan below, taken at the level indicated by the bottom right insert. What is the structure pointed to by arrow 3?
a. Ascending aorta – arrow 4
b. Azygous vein – indicated by arrow 1, at same posterior level as descending aorta but on right side
c. Descending aorta – arrow 5, posterior to ascending aorta
d. Superior vena cava – arrow 3 points to superior vena cava, this is the correct answer.
Note: Arrow 2 indicates the right bronchus.
You are concerned that your patient may have compromised function of the mitral valve. The sound of the mitral valve is best heard at which of the following locations?
a. At the apex in the left fifth intercostal space in the midclavicular line
b. In the fifth intercostal space to the right of the sternum
c. In the second intercostal space to the left of the sternum
d. In the second intercostal space to the right of the sternum
You are concerned that your patient may have compromised function of the mitral valve. The sound of the mitral valve is best heard at which of the following locations?
a. At the apex in the left fifth intercostal space in the midclavicular line – correct answer
b. In the fifth intercostal space to the right of the sternum – tricuspid valve best heard here
c. In the second intercostal space to the left of the sternum – pulmonary valve best heard here
d. In the second intercostal space to the right of the sternum – aortic valve best heard here
A 38-year old man is evaluated for palpitations provoked by anxiety. The patient describes a sudden-onset pounding sensation in the chest, followed by lightheadedness and shortness of breath. The patient has no history of heart disease and family history is unremarkable. After evaluation, he is treated with verapamil (Calcium channel blocker) and reports marked improvement in the frequency of palpitation episodes. The tracing below shows the electrical activity of a specific type of cardiac cell in the patient’s heart.
Which of the following effects would verapamil administration most likely have on these cells?
a. Increased action potential amplitude
b. Decreased excitation and contraction coupling
c. Lowered threshold potential
d. Reduced refractory period
e. Slowed spontaneous depolarization
A 38-year old man is evaluated for palpitations provoked by anxiety. The patient describes a sudden-onset pounding sensation in the chest, followed by lightheadedness and shortness of breath. The patient has no history of heart disease and family history is unremarkable. After evaluation, he is treated with verapamil (Calcium channel blocker) and reports marked improvement in the frequency of palpitation episodes. The tracing below shows the electrical activity of a specific type of cardiac cell in the patient’s heart.
Which of the following effects would verapamil administration most likely have on these cells?
a. Increased action potential amplitude – see C below
b. Decreased excitation and contraction coupling - Verapamil does decrease the amount of intracellular calcium available for excitation-contraction coupling in cardiac myocytes. This is why verapamil can be harmful in patients with impaired ventricular function. However, the tracing shown corresponds to pacemaker action potentials (nodal cells), not cardiac myocyte action potential (non-nodal cells)
c. Lowered threshold potential – Threshold potential refers to amount of depolarization required to initiate an action potential. Class I (Na channel blockers) and class IV (Ca channel blockers) antiarrhythmics raise the threshold potential of non-nodal and nodal cells, respectively, by blocking the channels that trigger and action potential. This effect also results in decreased action potential amplitude(A) and decreased upslope.
d. Reduced refractory period – Verapamil would increase refractory period by slowing the recovery of inactivated calcium channels. Class III antiarrhythmics (K channel blockers) also increase the refractory period.
e. Slowed spontaneous depolarization – correct answer.
Explanation: the above tracing demonstrates the action potential of cardiac pacemaker cells such as the sinoatrial (SA) or atrioventricular(AV) nodes. The pacemaker action potential includes the following phases:
Phase 4 = spontaneous depolarization – slow influx of Na+ions (funny current) makes the membrane potential become more and more positive, which allows T-type (transient) Ca2+channels to open. This Ca2+influx further contributes to depolarization. As the pacemaker cell approaches threshold, L-type (long lasting) Ca2+channels begin to open, which further increases Ca2+ influx and significantly decreases time until threshold is reached.
Phase 0 = upstroke. Characterized by continuous opening of L-type Ca2+ channels. In cardiac pacemaker tissue, action potential upstroke is slow and gradual due to relatively slow influx of Ca2+ into the cell
Phase 3 = repolarization. Characterized by the opening of K+channels and efflux of K+ from the cell, in conjunction with closure of Ca channels, which lead to repolarization of the cell membrane
A 5-year old girl is diagnosed with atrial septal defect. Her right heart is hypertrophied, with a fixed split of the second heart sound, a pulmonic diastolic murmur and a systolic murmur. Figure below shows the right ventricular pressures during a single heart beat. At what point is the fixed split of the second heart sound heard?
A
B
C
D
E
A 5-year old girl is diagnosed with atrial septal defect. Her right heart is hypertrophied, with a fixed split of the second heart sound, a pulmonic diastolic murmur and a systolic murmur. Figure below shows the right ventricular pressures during a single heart beat. At what point is the fixed split of the second heart sound heard?
A
B
C
D
E
Explanation: The second heart sounds occurs with the closing of the outlet valves of the right and left ventricles: the aortic and pulmonic valves, as the ventricle pressure is decreasing from the peak systolic pressure (choice D is correct). Increased right ventricular pressure will delay the closing of the pulmonic valve component of the second heart sound, so that a splitting of the sound will occur on auscultation.
Choice A = time of atrial contraction, which if it is heard, will represent the fourth heart sound (S4).
Choice B represents the closing of the AV valves of right and left heart (tricuspid and mitral), this is heard as the first heart sound.
Choice C = opening of outlet valves of heard, not heard on auscultation.
Choice E = opening of AV valves, not heard as well.
A 34-year old man comes to the clinic for evaluation of a heart murmur. The patient has no chest pain, palpitations, dizziness, shortness of breath at rest. He exercises regularly without any symptoms. Cardiac auscultation in the second right intercostal space reveals and ejection click along with a soft systolic murmur radiating to the neck. A normal volume and pressure tracing of the left ventricle is shown in the tracing below. Which of the following letters corresponds to the opening of the valve most likely affected in this patient?
A
B
C
D
A 34-year old man comes to the clinic for evaluation of a heart murmur. The patient has no chest pain, palpitations, dizziness, shortness of breath at rest. He exercises regularly without any symptoms. Cardiac auscultation in the second right intercostal space reveals and ejection click along with a soft systolic murmur radiating to the neck. A normal volume and pressure tracing of the left ventricle is shown in the tracing below. Which of the following letters corresponds to the opening of the valve most likely affected in this patient?
A
B
C
D
Explanation: This young, asymptomatic patient with a soft systolic ejection murmur at the right second intercostal space most likely has a bicuspid aortic valve. Aortic valve opening occurs when the LV pressure exceeds the central aortic pressure at the end of the isovolumetric contraction (B is correct).
Subsequently, LV pressure continues to rise with forward blood flow into the aorta, until the pressure in the LV falls below aortic pressure, leading to aortic valve closure (choice C).
Choice A = initial part of LV pressure and volume curve corresponds to atrial systole, which results in slight increase in LV volume and pressure. This is immediately followed by mitral valve closure and the beginning of isovolumetric contraction.
Choice D = left atrial pressure gradually increases from passive filling from the pulmonary veins and exceeds LV pressure at the end of isovolumetric relaxation, leading to the opening of the mitral valve.
A 72-year old man come to the ED due to left-sided weakness and speech difficulty on awakening this morning. He has a past medical history significant for hypertension and persistent atrial fibrillation. His anticoagulant medication was stopped 3 months ago due to an episode of gastrointestinal bleeding. A transthoracic echocardiogram shows left atrial enlargement and mild mitral regurgitation. The patient’s symptoms are determined to be caused by a thromboembolic event. Which of the following is the most likely source of the thrombus?
a. Crista terminalis
b. Left atrial appendage
c. Mitral valve
d. Left ventricular apex
e. Right atrial appendage
A 72-year old man come to the ED due to left-sided weakness and speech difficulty on awakening this morning. He has a past medical history significant for hypertension and persistent atrial fibrillation. His anticoagulant medication was stopped 3 months ago due to an episode of gastrointestinal bleeding. A transthoracic echocardiogram shows left atrial enlargement and mild mitral regurgitation. The patient’s symptoms are determined to be caused by a thromboembolic event. Which of the following is the most likely source of the thrombus?
a. Crista terminalis – refers to a thick band of atrial muscle that separates the smooth sinus venosus from the right atrial appendage and atrium proper. Not a significant region of thrombus formation in A fib.
b. Left atrial appendage – correct answer, see explanation below.
c. Mitral valve – Prostetic valve thrombosis can occur with mechanical mitral valves, not seen in patients with normal mitral valves
d. Left ventricular apex – thrombus can develop here in patients with severe generalized left ventricular systolic dysfunction or prior MI leading to impaired regional apical wall motion
e. Right atrial appendage – theoretically possible, but would embolize to the pulmonary vasculature and cause a PE
Explanation: Atrial fibrillation is associated with significant risk of systemic thromboembolism. Several factors contribute to thrombus development in A fib: left atrial enlargement, stasis of blood due to ineffective atrial contraction, atrial fibrosis (procoagulant effect).
The left atrial appendage is a small sacklike structure in the LA that is particularly susceptible to thrombus formation. These clots can then systemically embolize and lead to stroke, like in this patient.
Special electrodes are used to detect the changes in membrane potential of a specific type of cardiac cell. These changes are recorded on the graph below. The deflection indicated by the arrow is most likely caused by movement of which of the following ions?
a. Sodium
b. Potassium
c. Calcium
d. Chloride
Special electrodes are used to detect the changes in membrane potential of a specific type of cardiac cell. These changes are recorded on the graph below. The deflection indicated by the arrow is most likely caused by movement of which of the following ions?
a. Sodium – pacemaker cells have automaticity, made possible by a slow, inward sodium current that occurs during phase 4 of the action potential
b. Potassium – phase 3 repolarization is caused by an outward potassium channel
c. Calcium – correct answer. Graph illustrates action potential typical of cardiac pacemaker cells, like those found in the SA node. Arrow points to phase 0 depolarization caused by increased calcium conductance.
d. Chloride – does not contribute to any of the phases of the cardiac pacemaker AP
A 10-year old boy is brought to the clinic by his parents due to chronic fatigue, shortness of breath and failure to gain weight. Physical examination reveals a systolic murmur. Echocardiogram shows pulmonary stenosis and subaortic ventricular septal defect with deviation of the origin of the aorta to the right. The parents describe several episodes of severe dyspnea and cyanosis, during which the child quickly assumes a squatting position. Which of the following mechanisms during squatting relieves the child’s symptoms?
a. Decreasing pulmonary blood flow
b. Decreasing pulmonary vascular resistance
c. Increases lung compliance
d. Increasing systemic vascular resistance
A 10-year old boy is brought to the clinic by his parents due to chronic fatigue, shortness of breath and failure to gain weight. Physical examination reveals a systolic murmur. Echocardiogram shows pulmonary stenosis and subaortic ventricular septal defect with deviation of the origin of the aorta to the right. The parents describe several episodes of severe dyspnea and cyanosis, during which the child quickly assumes a squatting position. Which of the following mechanisms during squatting relieves the child’s symptoms?
a. Decreasing pulmonary blood flow – this increases, due to lower pulmonary : systemic vascular resistance ratio, see explanation below
b. Decreasing pulmonary vascular resistance
c. Increases lung compliance – not affected by squatting
d. Increasing systemic vascular resistance – correct answer, see explanation below
Explanation: The child has Tetralogy of Fallot with ventricular septal defect, overriding aorta, pulmonary stenosis and right ventricular hypertrophy. The pulmonary stenosis increases the pulmonary vascular resistance, while the overriding aorta (overrides the septal defect) leads to a lower systemic vascular resistance than normal. Therefore, deoxygenated right ventricular output takes the low-resistance route to the systemic circulation, leading to hypoxemia. Children with tetralogy of Fallot quickly learn to squat to relieve these hypoxemic episodes. This posture quickly increases systemic vascular resistance (D is correct), without affecting pulmonary vascular resistance (choice B). This forces a higher proportion of right ventricular output to enter the pulmonary circulation and oxygenate blood before it is distributed to the rest of the body.
