Cardiomegaly Case 4

Cardiomegaly Case 4

A 40-year-old man presents to the emergency department complaining of severe shortness of breath. The breathlessness has been worsening over the past few years, and the patient reports growing tachypneic with mild exertion, and sometimes even at night. On examination, he has generalized edema, jugular venous distention, and hepatic distention. Cardiac examination shows a right ventricular heave, a right-sided S3, and S4 with a pulmonary ejection click. A chest x-ray film shows cardiomegaly and widening of the hilar vessels, including the pulmonary arteries. An electrocardiogram shows talI, peaked P waves in leads lI, III, and aVF, right axis deviation, and right ventricular hypertrophy.

Q 1
Which of the following is the most likely diagnosis?
/ A. Cor pulmonale
/ B. Hypertrophic cardiomyopathy
/ C. Left ventricular failure
/ D. Myocardial infarction
/ E. Pulmonary embolus (acute)

Q 2
Pulmonary hypertension is suspected in the patient, and a Swan-Ganz catheter is placed. Which of the following denotes the correct
anatomic sequence of vessels that would be traversed by the catheter if it was introduced into the left subclavian vein?
/ A. Left subclavian vein, Ieft brachiocephalic vein, superior vena cava, right atrium, right ventricle, pulmonary artery
/ B. Left subclavian vein, Ieft common carotid, superior vena cava, right atrium, right ventricle, pulmonary artery
/ C. Left subclavian vein, Ieft jugular vein, Ieft atrium, Ieft ventricle, aorta
/ D. Left subclavian vein, Ieft jugular vein, superior vena cava, right atrium, right ventricle, pulmonary artery
/ E. Left subclavian vein, superior vena cava, right atrium, right ventricle, pulmonary artery

Q3
Calcium channel blockers can be used in this setting to decrease pulmonary vascular resistance. Which of the following is the calcium
channel blocker that will have the most predominant effect on vascular smooth muscle?
/ A. Diltiazem
/ B. Hydrochlorothiazide
/ C. Nifedipine
/ D. Pseudoephedrine
/ E. Verapamil

Q 4
Which of the following physiologic stimuli will result in decreased pulmonary vascular resistance?
/ A. Decreased cardiac output
/ B. Increased cardiac output
/ C. Low O2 tension
/ D. Lung volumes near residual volume (RV)
/ E. Lung volumes near total lung capacity (TLC)


Q 5
Some of the examination findings indicate hepatic congestion. Which of the following terms is commonly used to identify the macroscopic
pattern of red, depressed hepatic nodules with pale periphery that accompanies the chronic hepatic congestion seen in this condition?
/ A. Centrilobular hemorrhage
/ B. Cirrhosis
/ C. Fatty change
/ D. Nutmeg liver
/ E. Piecemeal necrosis

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Cardiomegaly Case 4 Answers
A1
The correct answer is A. This patient has cor pulmonale, which is defined as enlargement of the right ventricle secondary to diseases of the lung, thorax, or pulmonary circulation. In this case, it is chronic, given the duration of the patient's symptoms and the presence of many clinical sequelae of the condition: edema, jugular venous distention, hepatic distention, and right ventricular heave. The electrocardiogram also supports the diagnosis of enlargement of the right ventricle showing right axis deviation due to the increase in the mass of the right heart. Evidence of right atrial enlargement is also present, i.e., the tall peaked P waves in leads II, III, and aVF (P pulmonale).
Hypertrophic cardiomyopathy (choice B) is an anomaly in which the myocardium hypertrophies. The fibers are erratic and conduction abnormalities and outflow obstruction may result. Typically, this disorder presents in the second decade of life, and will manifest as dysrhythmia and/or shortness of breath. In addition, a right axis deviation would be inconsistent with this cardiomyopathy because the left ventricle hypertrophies, as well as the right. Thus, this diagnosis is unlikely.
Left ventricular failure (choice C) often accompanies right ventricular failure, but in this case, the right-sided symptoms, such as systemic edema, jugular venous distention, and hepatic congestion, are more pronounced. Left-sided failure shows engorgement of the entire pulmonary tree in conjunction with pulmonary edema.
Myocardial infarction (choice D) is unlikely. The ECG findings are not consistent with the pattern typically seen in MI. In addition, this patient does not suffer from the symptoms of myocardial infarction, such as chest pain, pressure, jaw numbness, and diaphoresis.
Pulmonary embolus (choice E) may cause acute right heart strain and failure, but this patient has a chronic condition. Chronic emboli may produce increased resistance in the pulmonary tree and a picture similar to this.

A2
The correct answer is A. The correct sequence for a catheter inserted into the left subclavian vein is as follows: left subclavian vein, left brachiocephalic vein, superior vena cava, right atrium, right ventricle, pulmonary artery. With this catheter in place, a variety of cardiac parameters can be measured, including pressures in the pulmonary artery. Thus, this catheter can aid in establishing the diagnosis of pulmonary hypertension

A3
The correct answer is C. The calcium channel blockers vary in the propensity to affect vascular smooth muscle versus their effect on cardiac muscle. Thus, in this case, it is important to select an agent that has maximum ability to relax the smooth muscle in the pulmonary vessels. The effect on smooth muscle is as follows: nifedipine>diltiazem >verapamil . The effect on cardiac muscle is as follows: verapamil>diltiazem>nifedipine. Thus nifedipine is the agent of choice.
Hydrochlorothiazide (choice B) is a diuretic, and thus would have no effect on the vascular smooth muscle.
Pseudoephedrine (choice D) is an alpha agonist, and therefore would cause vasoconstriction.

A4
The correct answer is B. A unique feature of the pulmonary circulation is that it maintains itself as a low-pressure system. Many of the mechanisms that control pulmonary vasculature differ from those of the systemic circulation. One of these features is that pulmonary vasculature resistance is decreased in response to increased cardiac output. This is accomplished through distention of open capillaries and the recruitment of collapsed capillaries. Thus, the resistance in the pulmonary tree decreases in response to increased right ventricular output. In the pathologic state of pulmonary hypertension, in which the resistance is elevated and the ventricle fails, this decreased cardiac output (choice A) may compound the problem and trigger increased resistance in spite of the primary elevation.
Low O2 tension (choice C) in the pulmonary vessels initiates vasoconstriction. In the systemic circulation, low O2 tension initiates vasodilation.
Lung volume also affects pulmonary vascular resistance. The curve of lung volume versus pulmonary vascular resistance is U-shaped. This effect is due to the fact alveolar and extra-alveolar vessels act as resistors in series (additive), and these vessels have little intrinsic support. Thus, resistance in these vessels is affected by pleural pressures. At low lung volumes (choice D), the alveolar vessels are open, but extra-alveolar vessels are compressed. At high lung volumes (choice E), the alveolar vessels are compressed by distended alveoli, but the extra-alveolar vessels become distended due to the increase in transmural pressure. Thus a U-shaped curve describes this relationship.

A5
The correct answer is D. Chronic passive congestion of the liver leads to a macroscopic pattern known as nutmeg liver. This is due to the congestion of blood in the centrilobular region (dark) with hypoxia and fatty change in the more peripheral hepatocytes. When viewed macroscopically, this pattern resembles that seen in a cross section of a nutmeg, hence the name.
In this condition, centrilobular hemorrhage (choice A) usually only occurs in severe acute ischemia. This patient has a chronic condition, and thus most likely will have nutmeg liver instead.
Cirrhosis (choice B) of the liver may result from chronic damage caused by chronic congestion. It however produces a scarred, whitish, shrunken liver, and not the pattern seen here.
Fatty liver (choice C) would produce a large, smooth yellow liver and would not resemble the pattern seen here.
Piecemeal necrosis (choice E) is a microscopic finding of scattered hepatocellular necrosis. This diagnosis cannot be made macroscopically.