Cardiovascular Disorders - Merck Manuals Professional Edition

Approach to the Cardiac Patient

Symptoms or the physical examination may suggest a cardiovascular disorder. For confirmation, selected noninvasive and invasive cardiac tests are usually done.
Symptoms of Cardiovascular Disorders

Chest pain is a very common complaint. Many patients are well aware that it is a warning of potential life-threatening disorders and seek evaluation for minimal symptoms. Other patients, including many with serious disease, minimize or ignore its warnings. Pain perception (both character and severity) varies greatly between individuals as well as between men and women. However described, chest pain should never be dismissed without an explanation of its cause.
Cardiovascular Tests and Procedures

Many noninvasive and invasive tests can delineate cardiac structure and function (see table Tests for Assessing Cardiac Anatomy and Function). Also, treatments can be administered during certain invasive diagnostic tests (eg, percutaneous coronary intervention during cardiac catheterization, radiofrequency ablation during electrophysiologic testing).
Overview of Arrhythmias and Conduction Disorders

The normal heart beats in a regular, coordinated way because electrical impulses generated and spread by myocytes with unique electrical properties trigger a sequence of organized myocardial contractions. Arrhythmias and conduction disorders are caused by abnormalities in the generation or conduction of these electrical impulses or both.
Specific Cardiac Arrhythmias

Atrial fibrillation is a rapid, irregularly irregular atrial rhythm. Symptoms include palpitations and sometimes weakness, effort intolerance, dyspnea, and presyncope. Atrial thrombi may form, causing a significant risk of embolic stroke. Diagnosis is by electrocardiography. Treatment involves rate control with drugs, prevention of thromboembolism with anticoagulation, and sometimes conversion to sinus rhythm by drugs or cardioversion.
Arrhythmogenic Cardiac Disorders

Although any dilated or hypertrophic cardiomyopathy (see Overview of Cardiomyopathies) can produce cardiac and systemic factors that predispose to a number of different arrhythmias, including bradyarrhythmias, atrial and ventricular tachyarrhythmias, and sudden death, certain cardiomyopathies are particularly prone to do so. These are referred to as arrhythmogenic cardiomyopathies and include
Arteriosclerosis

Atherosclerosis is characterized by patchy intimal plaques (atheromas) that encroach on the lumen of medium-sized and large arteries. The plaques contain lipids, inflammatory cells, smooth muscle cells, and connective tissue. Risk factors include dyslipidemia, diabetes, cigarette smoking, family history, sedentary lifestyle, obesity, and hypertension. Symptoms develop when growth or rupture of the plaque reduces or obstructs blood flow; symptoms vary by artery affected. Diagnosis is clinical and confirmed by angiography, ultrasonography, or other imaging tests. Treatment includes risk factor, lifestyle, and dietary modification; physical activity; antiplatelet drugs; and antiatherogenic drugs.
- Atherosclerosis
- Nonatheromatous Arteriosclerosis
Cardiac Tumors

Cardiac tumors may be primary (benign or malignant) or metastatic (malignant). Myxoma, a benign tumor, is the most common type of primary cardiac tumor. Cardiac tumors may occur in any cardiac tissue. They can cause valvular or inflow-outflow tract obstruction, thromboembolism, arrhythmias, or pericardial disorders. Diagnosis is by echocardiography and frequently cardiac MRI. Treatment of benign tumors is usually surgical resection; tumors may recur. Treatment of metastatic cancer depends on tumor type and origin; prognosis is generally poor.
- Cardiac Tumors
Cardiomyopathies

A cardiomyopathy is a primary disorder of the heart muscle. It is distinct from structural cardiac disorders such as coronary artery disease, valvular disorders, and congenital heart disorders. Cardiomyopathies are divided into 3 main types based on the pathologic features (see figure Forms of cardiomyopathy):
Coronary Artery Disease

Coronary artery disease (CAD) involves impairment of blood flow through the coronary arteries, most commonly by atheromas. Clinical presentations include silent ischemia, angina pectoris, acute coronary syndromes ( unstable angina, myocardial infarction), and sudden cardiac death. Diagnosis is by symptoms, ECG, stress testing, and sometimes coronary angiography. Prevention consists of modifying reversible risk factors (eg, hypercholesterolemia, hypertension, physical inactivity, obesity, diabetes, smoking). Treatment includes drugs and procedures to reduce ischemia and restore or improve coronary blood flow.
Diseases of the Aorta and Its Branches

Aneurysms are abnormal dilations of arteries caused by weakening of the arterial wall. Common causes include hypertension, atherosclerosis, infection, trauma, systemic rheumatic diseases, and connective tissue disorders (eg, Marfan syndrome, Ehlers-Danlos syndrome). Aneurysms are usually asymptomatic but can cause pain and lead to ischemia, thromboembolism, spontaneous dissection, and rupture, which may be fatal. Diagnosis is by imaging tests (eg, ultrasonography, CT angiography, magnetic resonance angiography, aortography). Unruptured aneurysms may be treated with medical management or repaired, depending on symptoms and the size and location of the aneurysm. Medical management includes risk factor modification (eg, strict blood pressure control) plus scheduled surveillance imaging. Repair can be done with either an open surgical or endovascular approach. Treatment of ruptured aneurysms is immediate repair.
Endocarditis

Infective endocarditis is infection of the endocardium, usually with bacteria (commonly, streptococci or staphylococci) or fungi. It may cause fever, heart murmurs, petechiae, anemia, embolic phenomena, and endocardial vegetations. Vegetations may result in valvular incompetence or obstruction, myocardial abscess, or mycotic aneurysm. Diagnosis requires demonstration of microorganisms in blood and usually echocardiography. Treatment consists of prolonged antimicrobial treatment and sometimes surgery.
- Infective Endocarditis
- Noninfective Endocarditis
Heart Failure

Heart failure (HF) is a syndrome of ventricular dysfunction. Left ventricular (LV) failure causes shortness of breath and fatigue, and right ventricular (RV) failure causes peripheral and abdominal fluid accumulation; the ventricles can be involved together or separately. Diagnosis is initially clinical, supported by chest x-ray, echocardiography, and levels of plasma natriuretic peptides. Treatment includes patient education, diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, beta-blockers, aldosterone antagonists, sodium-glucose cotransporter-2 inhibitors, neprilysin inhibitors, sinus node inhibitors, specialized implantable pacemakers/defibrillators and other devices, and correction of the cause(s) of the HF syndrome.
Hypertension

Hypertension is sustained elevation of resting systolic blood pressure (≥ 130 mm Hg), diastolic blood pressure (≥ 80 mm Hg), or both. Hypertension with no known cause (primary; formerly, essential, hypertension) is most common. Hypertension with an identified cause (secondary hypertension) is usually due to primary aldosteronism. Sleep apnea, chronic kidney disease, obesity, or renal artery stenosis are other causes of secondary hypertension. Usually, no symptoms develop unless hypertension is severe or long-standing. Diagnosis is by sphygmomanometry. Tests may be done to determine cause, assess organ damage, and identify other cardiovascular risk factors. Treatment involves lifestyle changes and medications, including diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, and calcium channel blockers.
Lymphatic Disorders

Plasma, along with some white blood cells, routinely moves out of capillaries into the interstitial space. Most of the fluid and its constituents is taken up by tissue cells or reabsorbed into the vascular tree, depending on the balance of hydrostatic and oncotic pressures. However, some of the fluid, along with certain cells and cellular debris (eg, from the immune response to local infection, cancer, inflammation) enters the lymphatic system.
Myocarditis and Pericarditis

Myocarditis is inflammation of the myocardium with necrosis of cardiac myocytes. Myocarditis may be caused by many disorders (eg, infection, cardiotoxins, drugs, and systemic disorders such as sarcoidosis) but is often idiopathic. Symptoms can vary and can include fatigue, dyspnea, edema, palpitations, and sudden death. Diagnosis is based on symptoms and clinical findings of abnormal electrocardiography (ECG), cardiac biomarkers, and cardiac imaging in the absence of cardiovascular risk factors. Endomyocardial biopsy confirms clinical diagnosis of myocarditis. Treatment depends on the cause, but general measures include drugs to treat heart failure and arrhythmias and rarely surgery (eg, intra-aortic balloon pump, left ventricular assist device, transplantation). Immunosuppression is of use in certain types of myocarditis (eg, hypersensitivity myocarditis, giant cell myocarditis, myocarditis caused by sarcoidosis)..
- Myocarditis
- Pericarditis
Peripheral Arterial Disorders

Acrocyanosis is persistent, painless, symmetric cyanosis of the hands, feet, or face caused by vasospasm of the small vessels of the skin in response to cold.
Peripheral Venous Disorders

An arteriovenous fistula is an abnormal communication between an artery and a vein.
Sports and the Heart

Athlete’s heart is a constellation of structural and functional changes that occur in the heart of people who train for prolonged durations (eg,> 1 hour most days) and/or frequently at high intensities. The changes are asymptomatic; signs include bradycardia, a systolic murmur, and extra heart sounds. Electrocardiographic (ECG) abnormalities are common. Diagnosis is clinical or by echocardiography. No treatment is necessary. Athlete’s heart is significant because it must be distinguished from serious cardiac disorders.
- Athlete’s Heart
- Sudden Cardiac Death in Athletes
Valvular Disorders

Any heart valve can become stenotic or insufficient (also termed regurgitant or incompetent), causing hemodynamic changes long before symptoms occur. Depending on which valve is involved, the most common symptoms include dyspnea, fatigue, and peripheral edema. Most often, valvular stenosis or insufficiency occurs in isolation in individual valves, but multiple valvular disorders may coexist, and a single valve may be both stenosed and insufficient.