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208. APPROACH TO THE PATIENT WITH CARDIOVASCULAR DISEASE - Eugene Braunwald
THE MAGNITUDE OF THE PROBLEM
Cardiovascular diseases comprise the most prevalent serious disorders in the developed nations. The American Heart Association has reported that in 2002, 62
million Americans — 32 million females and 30 million males (i.e., more than one in five persons) — had a cardiovascular disease (including hypertension). The
prevalence rises progressively with age from 5% at age 20 to 75% at age >75 years.
Discharges from U.S. hospitals for cardiovascular disorders have been rising steadily and now exceed 6 million per year. Despite substantial progress in the primary
and secondary prevention of coronary heart disease, approximately 6.5 million Americans suffer from angina pectoris and more than 1 million experience a myocardial
infarction each year. About 4.8 million Americans have congestive heart failure and more than half a million new cases occur each year. Hospitalizations for heart
failure have risen from 400,000 to 950,000 per year in the past 20 years. More than 1.4 million patients undergo cardiac catheterization each year, and approximately
1.2 million undergo revascularization (either percutaneous coronary intervention or coronary artery bypass grafting). There are approximately 1 million Americans with
congenital heart disease now alive, and 40,000 babies with congenital heart disease are born each year. The annual total costs of cardiovascular diseases are
estimated at $280 billion — $170 billion in direct costs and $110 billion in indirect costs in lost productivity.
Although age-adjusted death rates for coronary heart disease have declined by two-thirds from their peak in 1965, cardiovascular diseases remain the most common
causes of death, responsible for 40% of all deaths, almost 1 million deaths each year. Approximately one-fourth of these deaths are sudden. Among developed
nations, death rates from cardiovascular diseases are highest in the nations of the former Soviet Union, are intermediate in the United States and Western Europe,
and lowest in Japan. The prevalence of cardiovascular disease, especially coronary artery disease, is rising alarmingly in China, India, Pakistan, and the Middle East,
as nutritional and infectious causes of death decline in these regions. It has been projected that by 2020 cardiovascular diseases will be the leading causes of death
worldwide.
CARDIAC SYMPTOMS
The symptoms caused by heart disease result most commonly from myocardial ischemia, from disturbance of the contraction and/or relaxation of the myocardium,
from obstruction to blood flow, or from an abnormal cardiac rhythm or rate. Ischemia is manifest most frequently as chest discomfort, while reduction of the pumping
ability of the heart commonly leads to fatigability and shortness of breath or, when severe, produces cyanosis, hypotension, syncope, and elevated intravascular
pressure behind a failing ventricle. The latter results in abnormal fluid accumulation, which in turn leads to dyspnea, orthopnea, and systemic or pulmonary edema.
Obstruction to blood flow, as in valvular stenosis, can cause symptoms resembling those resulting from congestive heart failure. Cardiac arrhythmias often develop
suddenly, and the resulting signs and symptoms — palpitation, dyspnea, hypotension, presyncope, and syncope — generally occur abruptly and may disappear as
rapidly as they develop. Ischemic heart disease, by far the most common form of heart disease in adults, may present with chest discomfort but also as heart failure,
tachyarrhythmia, and sudden cardiac death.
Myocardial or coronary function that may be adequate at rest may be inadequate during exertion. Thus chest discomfort and/or dyspnea that appear only during
activity are characteristic of heart disease, while the opposite pattern, i.e., the appearance of these symptoms at rest and their remission during exertion, is rarely
observed in patients with organic heart disease.
Many patients with cardiocirculatory disease may also be asymptomatic, both at rest and during exertion, but may present an abnormal physical finding, such as a
heart murmur, elevated arterial pressure, or an abnormality of the electrocardiogram (ECG) or of the cardiac silhouette on the chest roentgenogram. Patients may
exhibit asymptomatic ischemia on an exercise stress test. In some asymptomatic patients the first clinical event may be catastrophic — sudden cardiac death, acute
myocardial infarction, or stroke.
FEAR OF HEART DISEASE
Diseases of the heart and circulation are so common and the laity is so well acquainted with the major symptoms resulting from these disorders that patients, and
occasionally physicians, erroneously attribute many noncardiac complaints to cardiovascular disease. The combination of the widespread fear of heart disease with
the deep-seated emotional connotations concerning this organ's function results in the frequent development of symptoms that mimic those of organic disease in
persons with normal cardiovascular systems. The unraveling of symptoms and signs due to organic heart disease from those not directly related is an important and
challenging task in such patients.
Patients in whom heart disease has been confirmed, especially those who have experienced a major cardiovascular event such as a myocardial infarction or a serious
arrhythmia, are often frightened and anxious about hospital discharge and resuming normal activity, including sexual relations. Attention to these matters is vital in the
care of cardiac patients.
Dyspnea, one of the cardinal manifestations of heart failure, is not limited to patients with heart disease but is also observed in conditions as diverse as pulmonary
disease, marked obesity, and anxiety (Chap. 29). Similarly, chest discomfort may result from a variety of causes other than myocardial ischemia ( Chap. 12). Whether
heart disease is responsible for these symptoms can frequently be determined by carrying out a careful clinical examination. Noninvasive testing using
electrocardiography at rest and during exercise ( Chap. 210), echocardiography (Chap. 211), roentgenography, and myocardial imaging usually provides important
additional information to permit the correct interpretation of symptoms; more specialized invasive examinations (catheterization and angiography; Chap. 212) are
occasionally necessary.
DIAGNOSIS
As outlined by the New York Heart Association, the elements of a complete cardiac diagnosis include consideration of the following:
1. The underlying etiology. Is the disease congenital, infectious, hypertensive, or ischemic in origin?
2. The anatomic abnormalities. Which chambers are involved? Are they hypertrophied, dilated, or both? Which valves are affected? Are they regurgitant and/or
stenotic? Is there pericardial involvement? Has there been a myocardial infarction?
3. The physiologic disturbances. Is an arrhythmia present? Is there evidence of congestive heart failure or of myocardial ischemia?
4. Functional disability. How strenuous is the physical activity required to elicit symptoms? The classification provided by the New York Heart Association has been
found to be useful in describing functional disability ( Table 208-1).
One example may serve to illustrate the importance of establishing a complete diagnosis. In a patient who presents with exertional chest pain, the identification of
myocardial ischemia as the etiology is of great clinical importance. However, the simple recognition of ischemia is insufficient to formulate a therapeutic strategy or
prognosis until the underlying anatomic abnormalities responsible for the myocardial ischemia, e.g., coronary atherosclerosis or aortic stenosis, are identified and a
judgment made as to whether other physiologic disturbances that cause an imbalance between myocardial oxygen supply and demand, such as severe anemia,
thyrotoxicosis, or supraventricular tachycardia, play a contributory role. Finally, the severity of the disability will govern the extent and tempo of the workup and
strongly influence the therapeutic strategy that is selected.
The establishment of a correct and complete cardiac diagnosis often commences with the history and physical examination ( Chap. 209). Indeed, the clinical
examination remains the basis for the diagnosis of a wide variety of disorders ( Table 208-2). The clinical examination may then be supplemented by four types of
laboratory tests: (1) ECG1 (Chap. 210); (2) chest roentgenogram; (3) noninvasive graphic examinations (echocardiogram, radionuclide and imaging techniques;
Chap. 211); and occasionally (4) specialized invasive examinations, i.e., cardiac catheterization, angiocardiography, and coronary angiography ( Chap. 212).
THE DIAGNOSTIC PROCESS
In the diagnostic process, the results obtained from each of these several modalities should be analyzed independently of one another as well as together. Only in
this way can one avoid overlooking a subtle, though important, finding. For example, an ECG1 should be obtained in every patient suspected of heart disease. It may
provide the critical clue in establishing the correct diagnosis, e.g., the finding of a mild atrioventricular conduction disturbance in a patient with unexplained syncope,
even when all other methods of examination reveal no abnormal findings, can be the clue that advanced heart block and asystole might be the cause and can dictate
electrophysiologic testing. On the other hand, when combined intelligently with the results of other methods of examination, the ECG may provide essential
confirmatory data. Thus, the knowledge that a patient has an apical diastolic rumbling murmur may direct particular attention to the P waves, and the recognition of
electrocardiographic left atrial enlargement supports the suggestion that the murmur is caused by mitral stenosis. The diagnosis can then be confirmed by
echocardiography, a technique that can also determine the severity of the obstruction and its effects on pulmonary artery pressure and on right and left ventricular
function.
FAMILY HISTORY
In eliciting the history of a patient with known or suspected cardiovascular disease, particular attention should be directed to the family history. Familial clustering is
common in many forms of heart disease. Mendelian transmission of single-gene defects may occur, as in hypertrophic cardiomyopathy ( Chap. 221), the Marfan
syndrome (Chap. 342), and sudden death associated with a prolonged QT syndrome ( Chap. 214). Essential hypertension or coronary atherosclerosis are often
polygenic disorders. While familial transmission may be less obvious than in the single-gene disorders, it is also helpful in assessing risk and prognosis. Familial
clustering of cardiovascular diseases may occur not only on a genetic basis but may also be related to familial dietary or behavior patterns, such as excessive
ingestion of salt or calories or cigarette smoking.
ASSESSMENT OF FUNCTIONAL IMPAIRMENT
When an attempt is made to determine the severity of functional impairment in a patient with heart disease, it is helpful to ascertain with as much precision as possible
the level of activity and the rate at which it is performed before symptoms develop. Thus, it is not sufficient to state that the patient complains of dyspnea. The
breathlessness that occurs after running up two long flights of stairs denotes far less functional impairment than similar symptoms occurring after taking a few steps
on the level. Also, the degree of customary physical activity at work and during recreation should be considered. The development of two-flight dyspnea in a
well-conditioned marathon runner may be far more significant than the development of one-flight dyspnea in a previously sedentary person. Similarly, the history must
include a detailed consideration of the patient's therapeutic regimen. For example, the persistence or development of edema, breathlessness, and other
manifestations of heart failure in a patient whose diet is rigidly restricted in sodium content and who is receiving optimal doses of diuretics is far more grave than are
similar manifestations in the absence of these measures. In an effort to determine the progression of symptoms, and thereby the severity of the underlying illness, it
may be useful to ascertain what, if any, specific tasks the patient could carry out 1 year earlier that he or she cannot carry out at present.
THE PATIENT WITH A HEART MURMUR (FIG. 208-1)
The cause of a heart murmur can often be readily elucidated from a systematic evaluation of its major attributes: timing, duration, intensity, quality, frequency,
configuration, location, radiation, and response to maneuvers when considered in the light of the history, general physical examination, and other features of the
cardiac examination, as described in Chap. 209.
The majority of heart murmurs are midsystolic and soft (grades I to II/VI). When such a murmur occurs in an asymptomatic child or young adult without other evidence
of heart disease on clinical examination, it is usually benign and echocardiography is not generally required. On the other hand, two-dimensional and Doppler
echocardiography (Chap. 211) are indicated in patients with loud systolic murmurs (grades =III/VI), especially those that are holosystolic or late systolic; in most
patients with diastolic or continuous murmurs; and in patients with additional unexplained abnormal physical findings on cardiac examination.
ELECTROCARDIOGRAM (SEE ALSO CHAP. 210)
Although an ECG1 should be recorded in every patient with known or suspected heart disease, with the exception of the identification of arrhythmias and of acute
myocardial infarction, it rarely permits establishment of a specific diagnosis. The range of normal electrocardiographic findings is wide, and the tracing can be affected
significantly by many noncardiac factors, such as age, body habitus, and serum electrolyte concentrations. In the absence of other abnormal findings,
electrocardiographic changes must not be overinterpreted.
NATURAL HISTORY
Cardiovascular disorders often present acutely, as in a previously asymptomatic patient with extensive coronary atherosclerosis who develops an acute myocardial
infarction (Chap. 228) or the previously asymptomatic patient with hypertrophic cardiomyopathy ( Chap. 221) whose first clinical manifestation is syncope or even
sudden death. However, in both instances, the alert physician may recognize the patient at risk of these complications long before they occur and can often take
measures to prevent their occurrence. For example, the patient with acute myocardial infarction may well have had risk factors for atherosclerosis for many years. Had
these been recognized, their elimination or reduction might have delayed or even prevented the infarction. Similarly, the patient with hypertrophic cardiomyopathy may
have had a heart murmur for years, and a positive family history might have led to an echocardiographic examination and the recognition of the condition and
appropriate therapy long before the acute manifestations.