Epidemiology

Many medical conditions can affect the cardiac valves, including congenital heart disease, infectious or rheumatic causes, and complications of ischemic heart disease. However, in the United States, because of the aging population, degenerative valve disease is the most common cause of valvular pathology. This inflammatory damage to cardiac valves, though of much later onset than rheumatic heart disease and pathologically similar to atherosclerosis, has become an increasingly common cause of valvular heart disease (VHD) in developed nations. In contrast, on a global basis, rheumatic heart disease still remains a major causative agent of VHD.

The American Heart Association/American College of Cardiology has published guidelines for assessment, diagnostic testing, and medical and surgical treatment of VHD.¹ However, there are still many practice guidelines that are based on observational studies instead of randomized controlled trials. Recent trends in care include identifying subgroups of asymptomatic patients who may benefit from surgical intervention, valvular repair rather than replacement, and minimally invasive or percutaneous options.

Pathophysiology and Presenting Signs and Symptoms

Of the four heart valves, three are tricuspid (aortic, pulmonic, and tricuspid) and one is bicuspid (mitral). Failure of normal function of these valves is due to lesions that make them incompetent and allow backward flow (regurgitation) or to lesions that decrease orifice size and cause restriction of flow (stenosis). In addition, combinations of these lesions may occur within the same valve, and multiple valves may be involved (commonly the aortic and mitral valves with rheumatic heart disease). Cardiac murmurs result from (1) increased blood flow across a normal or abnormal valve orifice, (2) turbulent flow across a narrow or irregular orifice into a dilated blood vessel or cardiac chamber, or (3) backward flow across an incompetent valve or other cardiac defect. However, most systolic murmurs are related to a physiologic increase in blood velocity and are not pathologic.

Physical examination establishes where the murmur occurs within the cardiac cycle and its location, duration, and intensity. Murmurs are classified as systolic, diastolic, and continuous. Systolic murmurs are further subclassified into holosystolic (pansystolic), midsystolic, early systolic, and late systolic. Clicks can be heard from the snapping shut of diseased valves. Diastolic and continuous murmurs are nearly always pathologic and require investigation, even in the absence of symptoms. Although many systolic murmurs merit investigation, especially those associated with symptoms, the majority of systolic murmurs do not signify valvular disease.² A summary of the typical findings in the major valvular abnormalities is presented in Table 61.1.

Table 61.1 Characteristics of Common Cardiac Murmurs

A heart affected by valvular pathology has the ability to compensate over time, and symptoms are commonly absent for decades. Emergency physicians need to be able to identify when certain valvular lesions have progressed to the point that they are clinically important and responsible for the patient’s symptom complex. Shortness of breath, arrhythmias, and heart failure are common reasons why patients with VHD seek treatment at an ED. Other clinical scenarios include valve infection, myocardial infarction with papillary muscle dysfunction, and failure of a prosthetic device, which can cause rapid heart failure and shock. It should be kept in mind that valvular pathology is in the differential diagnosis of patients with congestive heart failure, shock, and angina. The clinician should perform a careful cardiac examination with attention to pulses, quality, and murmur types and locations. Does the patient with an aortic stenosis murmur have symptoms of angina pectoris, syncope, or heart failure? Are signs of embolic phenomena present in a patient with fever and a prosthetic heart valve? It is important to identify patients with severe aortic stenosis before using certain medications with preload effects because these drugs can cause significant hypotension.

Patients with midsystolic murmurs, grade 2 or less, and no associated findings or symptoms do not need any further work-up other than a history and physical examination. Aortic sclerosis is the most common defect found in these patients and requires no other intervention. However, patients with holosystolic murmurs, grade 3 murmurs, and diastolic or continuous murmurs should undergo further work-up with echocardiography.³ Some of these patients may eventually need cardiac catheterization if valve repair is planned. In patients with cardiopulmonary symptoms, detection of any new murmur warrants further investigation. The lack of a murmur in a patient with prosthetic heart valves may be pathologic and also requires further evaluation.

Clues about the significance of the VHD can be gleaned from chest radiography and electrocardiography (ECG). One may note valvular calcifications, asymmetric chambers sizes, and prosthetic valves. ECG may reveal signs of left atrial enlargement with tall or biphasic P waves, as well as left ventricular hypertrophy (LVH) or atrial fibrillation (AF).

Differential Diagnosis and Medical Decision Making

Valvular causes must be kept in mind in patients with chest pain, shortness of breath, arrhythmia, syncope, or shock. Patients with fever and new heart murmurs may have infectious endocarditis. An aortic insufficiency (AI) murmur in a patient with chest pain would lead to a diagnostic work-up for aortic dissection. Patients sustaining blunt trauma may rarely have traumatic aortic injury and, though rare, acute traumatic valvular injury as well.

Priority Actions

A new diastolic murmur in a patient with chest or back pain should raise suspicion for aortic dissection and requires urgent testing and consultation, as well as control of the heart rate and blood pressure.

Patients with valvular heart disease may become hemodynamically unstable with rapid atrial fibrillation and require cardioversion.

Infectious endocarditis should be considered in all patients with a prosthetic valve and fever. Blood cultures and empiric antibiotics are indicated.

Beside echocardiography should be performed in patients with shortness of breath who have recently undergone prosthetic valve replacement to rule out pericardial tamponade.

Red Flags

A careful murmur examination should be performed in patients with chest pain. Individuals with severe aortic stenosis are dependent on preload to maintain systolic blood pressure, and treatment with nitrates can cause severe hypotension.

Patients in cardiogenic shock from acute mitral regurgitation, aortic regurgitation, or prosthetic valve dysfunction may not have an appreciable murmur and require emergency echocardiography. These conditions are treated surgically and will require cardiac surgery consultation.

Emergency physicians need to recognize that the absence of a murmur or mechanical heart sound is pathologic in a patient with mechanical heart valve prosthesis.

Be vigilant in patients with a bicuspid valve and chest pain because of an increased risk for aortic dissection in these individuals.

Specific Valve Lesions

Aortic Stenosis

Aortic stenosis (AS) is the third most common form of cardiovascular disease in the Western world after hypertension and coronary artery disease. The most common causes of AS are calcification of a normal tricuspid valve and a congenital bicuspid aortic valve. Calcific degeneration of the aortic valve results from an inflammatory process similar to atherosclerotic vascular disease; it begins with intimal injury, such as calcification from the base of the cusps to the leaflets, which impairs motion, and progresses through fusion of valve leaflets and stenosis of the aortic valve orifice. When rheumatic heart disease is the culprit, the aortic valve commonly exhibits both stenosis and regurgitation and is usually associated with concomitant mitral valve disease.

The degree of aortic valve disease is based on several factors ⁴ (Table 61.2). Such assessment may be inaccurate and underestimate valve area and jet velocity in patients with impaired cardiac output. Progression of AS is usually quite slow, with symptoms taking decades to become manifested in most cases. An average 0.1-cm² decrease in valve area occurs per year.⁵ The left ventricle is faced with systolic pressure overload and compensates through hypertrophy of the left ventricular (LV) wall. Normal chamber volume is maintained, but with increased wall thickness. The hypertrophic wall may lead to decreased coronary blood flow, even in the absence of stenosis and angina. Diastolic dysfunction and heart failure symptoms may also be present. These patients are dependent on forceful atrial contraction to maintain elevated LV end-diastolic pressure (LVEDP) to overcome the obstruction to outflow. Therefore, individuals who have AF and AS may suffer hemodynamic consequences from loss of the atrial kick.

Table 61.2 Aortic Stenosis—Severity of Disease