Monday, January 14, 2008

35 - CVS pathology mcqs - 36 to 40

Question 36

A 51-year-old man has the sudden onset of substernal chest pain which radiates to his left arm and neck. He becomes light-headed and diaphoretic over the next 3 hours. He goes to the emergency room. On examination he is afebrile but has a heart rate of 96/minute with an irregular rhythm. Laboratory studies show a serum CK-MB of 15% with total CK of 524 mg/dL. Which of the following features would be most prominent by histopathologic examination of his myocardium at this point in time?
A Macrophage infiltration
B Contraction band necrosis
C Neutrophilic infiltration
D Capillary proliferation
E Collagen deposition

(B) CORRECT. This is an initial change as the myocardial fibers begin to die.
(A) Incorrect. Macrophages begin to appear at the end of the first week with an MI.
(C) Incorrect. Neutrophils begin to infiltrate the myocardium after the first day of an MI.
(D) Incorrect. Granulation tissue begins to form as the MI heals.
(E) Incorrect. Collagen is deposited in the healing phase of an MI.

Question 37
A 58-year-old man has had an enlarging abdomen for 5 months. He has experienced no abdominal or chest pain. On physical examination he has a non-tender abdomen with no masses palpable, but there is a fluid wave. An abdominal CT scan shows a large abdominal fluid collection with a small cirrhotic liver. A chest radiograph shows a globally enlarged heart. He has vital signs showing T 37.1 C, P 78/minute, RR 16/minute, and BP 115/75 mm Hg. Which of the following cardiovascular conditions is he most likely to have?
A Severe occlusive coronary atherosclerosis
B Lymphocytic myocarditis
C Myocardial amyloid deposition
D Nonbacterial thrombotic endocarditis
E Dilated cardiomyopathy

(E) CORRECT. The cardiomyopathy of chronic alcohol abuse has a dilated or congestive appearance.
(A) Incorrect. In general, persons with chronic alcoholism have less atherosclerosis.
(B) Incorrect. There is no increased risk for myocarditis in alcoholism.
(C) Incorrect. Alcoholism is not a risk factor for amyloidosis of any kind.
(D) Incorrect. Nonbacterial thrombotic endocarditis (NBTE) is a form of non-infective endocarditis that can occur in severely debilitated patients, though hypercoagulability that contributes to this process is not favored by chronic liver disease.

Question 38
A 77-year-old man has developed increasing dyspnea for the past 3 years. On physical examination he has a diastolic murmur. A chest radiograph shows an enlarged heart and prominent aorta. He dies from complications of pneumonia. At autopsy, the thoracic aorta is aneurysmally dilated. A microscopic section of the aorta shows chronic inflammation and luminal narrowing of vasa vasora. There is disruption of the aortic medial elastic fibers. Which of the following conditions is most likely to cause these findings?
A Hypercholesterolemia
B Marfan syndrome
C Polyarteritis nodosa
D Takayasu arteritis
E Tertiary syphilis
F Wegener granulomatosis

(E) CORRECT. T. pallidum is the organism that causes syphilis. The endaortitis of the vasa vasora affects the media of the aorta, leading to buckling of the intimal surface in a 'tree bark' pattern, and aneurysmal dilation, including the aortic root, causing aortic regurgitation. This happens decades following initial infection.
(A) Incorrect. Hypercholesterolemia is a risk factor for atheroscclerosis, which most often affects the abdominal aorta, leading to aneurysm formation. Mural thrombus is prone to develop when blood flow patterns are abnormal, as in an aneurysm.
(B) Incorrect. Marfan syndrome leads to cystic medial necrosis, not endaortitis, and appears earlier in life.
(C) Incorrect. Classic polyarteritis nodosa most often involves small to medium-sized muscular arteries, including renal and mesenteric arteries, and sometimes veins, with necrosis and microaneurysm formation.
(D) Incorrect. Takayasu arteritis can involve the aorta, particularly the arch, and branches such as coronary and renal arteries with granulomatous inflammation, aneurysm formation, and dissection. It appears at a much earlier age.
(F) Incorrect. Wegener granulomatosis involves small arteries, veins, and capillaries with mixed inflammation, necrotizing and non-necrotizing granulomatous inflammation withgeographic necrosis surrounded by palisading epithelioid macrophages and giant cells.

Question 39
A 23-year-old primigravida gives birth following an uncomplicated pregnancy to a 2870 gm girl infant. The baby initially does well, but then approximately 12 hours following delivery develops respiratory difficulty. On examination the infant has a poor color, weak pulses, and oxygen saturation of only 90%. Which of the following cardiac findings is this infant most likely to have?
A Muscular ventricular septal defect
B Hypoplastic left heart
C Complete transposition with no shunt
D Secundum type atrial septal defect
E Congenital infection with Group B streptococcus

(B) CORRECT. The poor outcome so soon after birth suggests a severe defect, and lack of sufficient left heart to provide appropriate cardiac output can explain these findings. There can be varying degrees of hypoplasia which determine how long the child survives.
(A) Incorrect. Even a large VSD should not be fatal in such a short time.
(C) Incorrect. If a transposition is present with no shunt, then any survival is not possible, as the systemic and pulmonary circulations would be completely separate.
(D) Incorrect. ASD's create a shunt, but the lack of a significant pressure difference between left and right atrium means that cardiac function is not severely affected.
(E) Incorrect. Group B strep infections may produce fetal or neonatal loss, but do not typically produce congenital heart defects. However, congenital rubella in the first trimester can lead to cardiac defects.

Question 40
A 66-year-old man has had increasing malaise for the past year. On physical examination auscultation of the chest reveals a friction rub. Laboratory studies show a serum urea nitrogen of 100 mg/dl and creatinine of 9.8 mg/dl. Which of the following forms of pericarditis is he most likely to have?
A Fibrinous
B Hemorrhagic
C Purulent
D Serous
E Constrictive

(A) CORRECT. The uremia leads to exudation of fibrin onto the epicardial and pericardial surfaces.
(B) Incorrect. This is more typical of tuberculosis or metastatic tumor.
(C) Incorrect. This is not common but can occur with spread of infection from lung or mediastinum.
(D) Incorrect. This is more typical for collagen vascular diseases.
(E) Incorrect. This is a late complication of tuberculous pericarditis. It may also follow cardiac surgery or radiation to the chest.

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