Schwartz's Principles of Surgery ABSITE and Board Review, 9th Ed.

CHAPTER 21. Acquired Heart Disease

BASIC SCIENCE QUESTIONS

1. Which of the following is the primary physiologic change in patients with heart failure?

A. Elevated left anterior (LA) end-diastolic pressure

B. Elevated LA end-systolic pressure

C. Elevated left ventricular (LV) end-diastolic pressure

D. Elevated LV end-systolic pressure

Answer: C

The physiologic change in most patients with heart failure is a rise in LV end-diastolic pressure, followed by cardiac enlargement. While Starling’s law describes the compensatory mechanism of the heart of increased work in response to increased diastolic fiber length, symptoms develop as this compensatory mechanism fails, resulting in a progressive rise in LV end-diastolic pressure. (See Schwartz 9th ed., p 628.)

2. The arterioventricular (AV) node is supplied by the right coronary artery in what percentage of patients?

A. 5%

B. 20%

C. 45%

D. 80%

Answer: D

The left coronary system supplies the major portion of the left ventricular (LV) myocardium through the left main, left anterior descending, and circumflex coronary arteries. The right coronary artery supplies the right ventricle, and the posterior descending artery supplies the inferior wall of the left ventricle. The AV nodal artery arises from the right coronary artery in 80 to 85% of patients, termed right dominant circulation. In 15 to 20% of cases, the circumflex branch of the left coronary system supplies the posterior descending branch and the AV nodal artery, termed left dominant, while 5% are codominant. (See Schwartz 9th ed., p 631.)

CLINICAL QUESTIONS

1. Classic angina occurs in what percentage of patients with coronary artery disease?

A. 40%

B. 56%

C. 75%

D. 90%

Answer: C

Classic angina is precordial pain described as squeezing, heavy, or burning in nature, lasting from 2 to 10 minutes. The pain is usually substernal, radiating into the left shoulder and arm, but occasionally occurs in the midepigastrium, jaw, right arm, or midscapular region. Angina usually is provoked by exercise, emotion, sexual activity, or eating, and is relieved by rest or nitroglycerin. Angina is present in its classic form in 75% of patients with coronary disease, while atypical symptoms occur in 25% of patients and more frequently in women. (See Schwartz 9th ed., p 628.)

2. Dyspnea is an early symptom in which of the following conditions?

A. Mitral stenosis

B. Mitral insufficiency

C. Aortic stenosis

D. Aortic insufficiency

Answer: A

Dyspnea may appear as an early sign in patients with mitral stenosis due to restriction of flow from the left atrium into the left ventricle. However, with other forms of heart disease, dyspnea is a late sign, as it develops only after the left ventricle has failed and the end-diastolic pressure rises significantly. Dyspnea associated with mitral insufficiency, aortic valve disease, or coronary disease represents relatively advanced pathophysiology. (See Schwartz 9th ed., p 628.)

The main symptoms of mitral stenosis are exertional dyspnea and decreased exercise capacity. Dyspnea occurs when the left atrial pressure becomes elevated due to the stenotic valve, resulting in pulmonary congestion. Orthopnea and paroxysmal nocturnal dyspnea may also occur, or in advanced cases, hemoptysis. (See Schwartz 9th ed., p 641.)

3. The most common cause of aortic stenosis is

A. Congenital

B. Acquired calcific disease

C. Bicuspid aortic valve

D. Rheumatic disease

Answer: B

In the adult North American population, the primary causes of aortic stenosis include acquired calcific disease, bicuspid aortic valve, and rheumatic disease. Acquired calcific aortic stenosis typically occurs in the seventh or eighth decade of life, and is the most frequent etiology, accounting for over half of the cases. Acquired calcific stenosis, also termed degenerative aortic stenosis or senile aortic stenosis, appears to be related to the aging process, with progressive degeneration leading to valve damage and calcification, although a causative role of lipids has been demonstrated recently. Lipid-lowering drugs seem to slow the progression of acquired calcific stenosis. Bicuspid aortic valve accounts for approximately one third of the cases of aortic stenosis in adults, typically presenting in the fourth or fifth decade of life, after years of turbulent flow through the bicuspid valve result in damage and calcification.

The third major cause of aortic stenosis, rheumatic heart disease, accounts for approximately 10 to 15% of patients in North America, but is more common in underdeveloped countries. With rheumatic disease, the degree of stenosis progresses with time. Concomitant MV disease almost always is present, although not always clinically significant. (See Schwartz 9th ed., p 647.)

4. Which of the following statements about thallium stress tests is FALSE?

A. A reversible defect on a thallium scan indicates a well-healed area of previous infarction

B. Initial uptake of thallium is dependent on myocardial perfusion

C. Delayed uptake of thallium is dependent on myocardial viability

D. The dipyridamole thallium study should be used in patients who cannot exercise

Answer: A

Currently the most widely used myocardial perfusion screening study is the thallium scan, which uses the nuclide thallium-201. Initial uptake of thallium-201 into myocardial cells is dependent upon myocardial perfusion, while delayed uptake depends on myocardial viability. Thus, reversible defects occur in under-perfused, ischemic, but viable zones, while fixed defects occur in areas of infarction. Fixed defects on the thallium scan suggest nonviable myocardium and may be of prognostic value. The exercise thallium test is widely used to identify inducible areas of ischemia and is 95% sensitive in detecting multivessel coronary disease. This is the best overall test to detect myocardial ischemia, but requires the patient to exercise on the treadmill. The study also gives excellent, specific information about the patient’s cardiac functional status. The dipyridamole thallium study is a provocative study using IV dipyridamole, which induces vasodilation and consequently unmasks myocardial ischemia in response to stress. This is the most widely used provocative study for risk stratification for patients who cannot exercise. In patients undergoing noncardiac surgery, the predictive value of a positive dipyridamole thallium study is 5 to 20% for MI or death, while a negative study is 99 to 100% predictive that a cardiac event will not occur. It is, therefore, a very effective screening study for moderate- to high-risk patients who require a general surgery procedure. (See Schwartz 9th ed., p 630.)

5. Which of the following is commonly seen in patients with chronic pericarditis?

A. Dyspnea at rest

B. Ascites

C. Chest pain

D. Cough

Answer: B

The pathophysiology of this disease remains the limitation of diastolic filling of the ventricles. This results in a decrease in cardiac output from a decrease in stroke volume. The right ventricular diastolic pressure is increased, with a corresponding increase in right atrial and central venous pressure ranging from 10 to 30 mmHg. This venous hypertension may produce hepatomegaly, ascites, peripheral edema, and a generalized increase in blood volume. The disease is slowly progressive with increasing ascites and edema. Fatigability and dyspnea on exertion are common, but dyspnea at rest is unusual. The ascites often is severe, and the diagnosis is easily confused with cirrhosis. Hepatomegaly and ascites often are the most prominent physical abnormalities. Peripheral edema is moderate in some patients, but severe in others. These findings are manifestations of advanced congestive failure from any form of heart disease. With constrictive pericarditis, however, the usual cardiac findings are a heart of normal size without murmurs or abnormal sounds. Atrial fibrillation is present in about one third of the patients, and a pleural effusion is common in more severe cases. A paradoxical pulse is found in a small proportion of patients. (See Schwartz 9th ed., pp 659-660.)

6. A patient who develops angina after walking one city block has

A. Canadian Cardiovascular Society Class I angina

B. Canadian Cardiovascular Society Class II angina

C. Canadian Cardiovascular Society Class III angina

D. Canadian Cardiovascular Society Class IV angina

Answer: C

(See Schwartz 9th ed., p 629, and Table 21-1.)

TABLE 21-1 Canadian Cardiovascular Society angina classification

Class I: Ordinary physical activity, such as walking or climbing stairs, does not cause angina. Angina may occur with strenuous or rapid or prolonged exertion at work or recreation.

Class II: There is slight limitation of ordinary activity. Angina may occur with walking or climbing stairs rapidly, walking uphill, walking or stair climbing after meals or in the cold, in the wind, or under emotional stress, or walking more than two blocks on the level, or climbing more than one flight of stairs under normal conditions at a normal pace.

Class III: There is marked limitation of ordinary physical activity. Angina may occur after walking one or more blocks on the level or climbing one flight of stairs under normal conditions at a normal pace.

Class IV: There is inability to carry on any physical activity without discomfort; angina may be present at rest.

7. Which of the following is the most common primary cardiac tumor?

A. Myxoma

B. Angiosarcoma

C. Fibroma

D. Fibrosarcoma

Answer: A

Primary cardiac neoplasms are rare, reported to occur with incidences ranging from 0.001 to 0.3% in autopsy series. Benign tumors account for 75% of primary neoplasms and malignant tumors account for 25%. The most frequent primary cardiac neoplasm is myxoma, comprising 30 to 50%. Other benign neoplasms, in decreasing order of occurrence, include lipoma, papillary fibroelastoma, rhabdomyoma, fibroma, hemangioma, teratoma, lymphangioma, and others. Most primary malignant neoplasms are sarcomas (angiosarcoma, rhabdomyosarcoma, fibrosarcoma, leiomyosarcoma, and liposarcoma), with malignant lymphomas accounting for 1 to 2%. (See Schwartz 9th ed., p 660.)

8. The differential diagnosis of syncope includes all of the following EXCEPT

A. Aortic stenosis

B. Hypertrophic cardiomyopathy

C. Tricuspid insufficiency

D. Vasovagal reaction

Answer: C

Syncope, or sudden loss of consciousness, is usually a result of sudden decreased perfusion of the brain. The differential diagnosis includes: (a) third-degree heart block with bradycardia or asystole, (b) malignant ventricular tachyarrhythmias or ventricular fibrillation, (c) aortic stenosis, (d) hypertrophic cardiomyopathy, (e) carotid artery disease, (f) seizure disorders, and (g) vasovagal reaction. Any episode of syncope must be evaluated thoroughly, as many of these conditions can result in sudden death. (See Schwartz 9th ed., p 629.)

9. Which of the following symptoms is a LATE symptom of chronic, untreated mitral insufficiency?

A. Atrial flutter

B. Pulmonary edema

C. Decreased LV ejection fraction

D. Decreased LA stroke volume

Answer: C

The basic physiologic abnormality in patients with mitral insufficiency is regurgitation of a portion of the LV stroke volume into the left atrium. This results in decreased forward blood flow and an elevated left atrial pressure, producing pulmonary congestion and volume overload of the left ventricle. As mitral insufficiency progresses, there is a corresponding increase in the size of the left atrium, and eventually, atrial fibrillation results. Concurrently, the left ventricle dilates. Initially the LV stroke volume increases by Starling’s law, but eventually, this compensatory mechanism fails, and the ejection fraction decreases. However, decreased systolic function of the heart is a relatively late finding, because the ventricle is “unloaded” as a result of the valvular insufficiency. Once LV dysfunction and heart failure develop, the left ventricle usually has been significantly and often irreversibly injured. (See Schwartz 9thed., p 642.)

10. Indications for aortic valve replacement in a patient with aortic stenosis include

A. Any LV dysfunction

B. Progressive pulmonary hypertension

C. Right ventricular dysfunction during exercise

D. All of the above

Answer: D

Aortic valve replacement is indicated for virtually all symptomatic patients with aortic stenosis. Even in patients with NYHA class IV symptoms and poor ventricular function, surgery has been found to improve both functional status and survival. In asymptomatic patients with moderate to severe stenosis, periodic echocardiographic studies are performed to assess the transvalvular gradient, valve area, LV size, and LV function. Surgery is indicated with the first sign of LV systolic dysfunction, manifest on echocardiography as either a rise in the LV end-systolic size or a drop in the LVEF. Surgery also may be recommended for asymptomatic patients with aortic stenosis who have a progressive increase in the transvalvular gradient on serial echocardiographic studies, a rapid rise in diastolic dimensions, a valve area 0.80 cm2, progressive pulmonary hypertension, or right ventricular dysfunction during exercise testing. (See Schwartz 9th ed., p 648.)

11. Which of the following is NOT a risk factor for coronary artery disease?

A. Elevated serum homocysteine

B. Female gender

C. Elevated lipoprotein (a)

D. Sedentary lifestyle

Answer: B

The etiology of CAD is primarily atherosclerosis. The disease is multifactorial, with the primary risk factors being hyperlipidemia, smoking, diabetes, hypertension, obesity, sedentary lifestyle, and male gender. Newly identified risk factors include elevated levels of C-reactive protein, lipoprotein (a), and homocysteine. (See Schwartz 9th ed., p 633.)

12. The most common cause of mitral valve stenosis is

A. Coronary artery disease

B. Congenital stenosis

C. Bacterial endocarditis

D. Rheumatic heart disease

Answer: D

MV stenosis or mixed mitral stenosis and insufficiency almost always are caused by rheumatic heart disease, although a definite clinical history can be obtained in only 50% of patients. (See Schwartz 9th ed., p 640.)

13. In the Ross procedure, the aortic valve is replaced with

A. A bileaflet mechanical valve

B. A stented porcine tissue valve

C. An unstented bovine tissue valve

D. The patient’s pulmonary valve

Answer: D

The Ross procedure involves replacement of the aortic valve with an autograft from the patient’s native pulmonary valve. The resected pulmonary valve is then replaced with a pulmonary homograft. (See Schwartz 9th ed., p 652.)

14. A patient with cardiac disease who is comfortable at rest but experiences angina if he walks 2 to 3 city blocks has

A. New York Heart Association Class 1 disease

B. New York Heart Association Class 2 disease

C. New York Heart Association Class 3 disease

D. New York Heart Association Class 4 disease

Answer: B

See Table 21-2. An important part of the history is the assessment of the patient’s overall cardiac functional disability, which is a good approximation of the severity of the patient’s underlying disease. The New York Heart Association (NYHA) has developed a classification of patients with heart disease based on symptoms and functional disability (Table 21-2). The NYHA classification has been extremely useful in evaluating a patient’s severity of disability, in comparing treatment regimens, and in predicting operative risk. (See Schwartz 9th ed., p 629.)

TABLE 21-2 New York Heart Association functional classification

Class I: Patients with cardiac disease but without resulting limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation, dyspnea, or angina pain.

Class II: Patients with cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or angina pain.

Class III: Patients with cardiac disease resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary physical activity causes fatigue, palpitation, dyspnea, or angina pain.

Class IV: Patients with cardiac disease resulting in an inability to carry on any physical activity without discomfort. Symptoms of cardiac insufficiency or of the anginal syndrome may be present even at rest. If any physical activity is undertaken, discomfort is increased.

15. Which of the following patients is most likely to benefit from coronary artery bypass?

A. Patients with CCS class I angina and double-vessel disease

B. Patients with single-vessel proximal right coronary artery disease and congestive heart failure

C. Patients with CCS class I angina and diabetes

D. Patients with CCS class II angina with hypertension

Answer: C

In some patients with chronic angina, CABG is associated with improved survival and improved complication-free survival when compared to medical management. In general, patients with more severe angina (CCS class III or IV symptoms) are most likely to benefit from bypass. For patients with less severe angina (CCS class I or II), other factors, such as the anatomic distribution of disease (left main coronary disease or triple-vessel) and the degree of LV dysfunction, are used to determine which patients will most benefit from surgical revascularization.

To summarize, although medical therapy may be appropriate for many patients with chronic stable angina, bypass surgery is indicated for most patients with multivessel disease and CCS class III or IV symptoms. In patients with milder (CCS class I or II) symptoms, surgery results in improved survival in those with left main stenosis and those with triple-vessel disease and depressed LV function or diabetes. (See Schwartz 9th ed., p 634.)

16. Which of the following is an indication for surgical repair or replacement of the mitral valve in a patient with mitral insufficiency?

A. Abnormal exercise testing

B. Recent onset of atrial fibrillation

C. Any symptom, even if LV function is normal

D. All of the above

Answer: D

According to the American College of Cardiology/American Heart Association guidelines, MV repair or replacement is recommended in any symptomatic patient with mitral insufficiency, even with normal LV function (defined as ejection fraction >60% and end-systolic dimension 45 mm). Surgery also is currently recommended in asymptomatic patients with severe mitral insufficiency if there are signs of LV systolic dysfunction (increased end-systolic dimension or decreased ejection fraction). Recent onset of atrial fibrillation, pulmonary hypertension, or an abnormal response to exercise testing are considered relative indications for surgery. (See Schwartz 9th ed., p 643.)

17. Cardiac myxomas are most commonly found in the

A. Right atrium

B. Right ventricle

C. Left atrium

D. Left ventricle

Answer: C

Sixty to 75% of cardiac myxomas develop in the left atrium, almost always from the atrial septum near the fossa ovalis. Most other myxomas develop in the right atrium; 20 have been reported in the right or left ventricle. (See Schwartz 9th ed., p 660.)

18. Which of the following is NOT a clinical marker of increased risk for a patient undergoing a general surgical procedure?

A. Prior stroke

B. Advanced age

C. Hypertension (controlled on medication)

D. Atrial fibrillation

Answer: C

Cardiac risk stratification for patients undergoing noncardiac surgery is a critical part of the preoperative evaluation of the general surgery patient. The joint American College of Cardiology/American Heart Association task force, chaired by Eagle, recently reported guidelines and recommendations, which are summarized in this section. In general, the preoperative cardiovascular evaluation involves an assessment of clinical markers, the patient’s underlying functional capacity, and various surgery-specific risk factors.

The clinical markers that predict an increased risk of a cardiac event during noncardiac surgery are divided into three grades. Major predictors include unstable coronary syndromes, including acute or recent MI and unstable angina (CCS class III or IV), decompensated heart failure (NYHA class IV), and significant arrhythmias and severe valvular disease. Intermediate predictors are mild angina (CCS class I or II), old MI, compensated heart failure (NYHA class II and III), diabetes, and renal insufficiency. Mild predictors are advanced age, uncontrolled systemic hypertension, irregular rhythm, prior stroke, abnormal electrocardiogram (ECG), and mild functional disability. (See Schwartz 9th ed., p 629.)

19. When compared to percutaneous coronary intervention, coronary artery bypass

A. Is less expensive

B. Provides a more complete relief of angina

C. Has a higher mortality rate

D. Has a lower morbidity rate

Answer: B

When comparing CABG to PCI for the treatment of patients with CAD, results demonstrate that with appropriate patient selection both procedures are safe and effective, with little difference in mortality. PCI is associated with less short-term morbidity, decreased cost, and shorter hospital stay, but requires more late reinterventions. CABG provides more complete relief of angina, requires fewer reinterventions, and is more durable. Additionally, CABG appears to offer a survival advantage in diabetic patients with multivessel disease. (See Schwartz 9th ed., p 634.)

20. Which of the following does NOT increase operative risk for patients undergoing coronary artery bypass?

A. Female gender

B. NYHA class II functional status

C. Hypertension

D. Large body surface area

Answer: B

Variables that have been identified as influencing operative risk according to STS risk modeling include: female gender, age, race, body surface area, NYHA class IV status, low ejection fraction, hypertension, PVD, prior stroke, diabetes, renal failure, chronic obstructive pulmonary disease, immunosuppressive therapy, prior cardiac surgery, recent MI, urgent or emergent presentation, cardiogenic shock, left main coronary disease, and concomitant valvular disease. (See Schwartz 9th ed., p 636.)