20181130-20181205 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
Learning objectives:
108a Identify the major structures seen in cross sections or axial CT at different levels of the thorax.
108a Describe the subdivisions of the mediastinum and the contents of each. (MKS1a)
112a- Explain normal cardiac anatomy (ventricular and atrial chambers, cardiac valves, great vessels) (MKS1a)
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.
Learning objectives:
108a- Trace the path of blood flow through the heart; describe the chambers and valves involved and the particular features associated with each.
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
Learning objectives:
111a Describe how the embryonic heart tube gets partitioned into the four chambers and the kinds of congenital heart defects that might arise from abnormal development
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.
Learning objectives:
108a Identify the major structures seen in cross sections or axial CT at different levels of the thorax.
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
Learning objectives:
111a Describe the embryonic circulatory pattern involving the embryo, yolk sac, and placenta, and the fate of the cardinal, vitelline, and umbilical system of veins.
111a Trace the flow of blood in the fetus with emphasis on the two shunts, and identify the changes that occur at birth to transform the system into the postnatal pattern.
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
Learning objectives
108a Describe the position of the heart in the thorax, its surface projection, and relation to the lungs and esophagus. Know where to place a stethoscope to hear sounds from the four valves.
112a Explain normal cardiac anatomy (ventricular and atrial chambers, cardiac valves, great vessels)
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.
Learning objectives:
108a Trace the path of blood flow through the heart; describe the chambers and valves involved and the particular features associated with each.
Which of the following correctly describes blood flow during fetal circulation?
A) IVC to the heart through the foramen ovale to the pulmonary artery to the patent ductus arteriosus and descending aorta
B) Umbilical vein to portal vein to the IVC to the ductus venosus
C) Umbilical vein to ductus venosus to IVC to the heart through the foramen ovale to the aorta
D) Deoxygenated blood goes to the right ventricle to the pulmonary artery to the ductus arteriosus to the descending aorta to the umbilical vein to the placenta
The correct answer is C. During fetal blood circulation there are 3 important shunts. Also, of note the umbilical vein is oxygenated with 80% O2 saturation while the umbilical arteries have low O2 saturation.
The three important shunts are 1) blood enters the fetus through the umbilical vein into the ductus venosus into the IVC. This bypasses hepatic circulation and the portal vein 2) highly oxygenated blood reaching the heart goes through the foramen ovale and into the aorta to supply the body and brain 3)deoxygenated blood enters the heart through the SVC, enters the right ventricle into the main pulmonary artery and is shunted to the descending aorta through the patent ductus arteriosus. This is due to high pulmonary artery resistance.
A is incorrect. Oxygenated blood goes through the foramen ovale in the right atrium into the left atrium and aorta, not to the pulmonary artery.
B is incorrect. The umbilical vein does not go to the portal vein, instead it is shunted through the ductus venosus into the IVC.
D is incorrect. Deoxygenated blood from the descending aorta goes to the umbilical arteries not the umbilical vein back to the placenta.
Learning Issue covered:
111a
Describe the embryonic circulatory pattern involving the embryo, yolk sac, and placenta, and the fate of the cardinal, vitelline, and umbilical system of veins.
Describe the unique anatomic features of the vasculature that provide for each regional circulations
