3.2 Cardiomyopathies & Valvular Heart Disease

Cardiomyopathies & Valvular Heart Disease

Cardiomyopathies are diseases of the heart muscle itself, while valvular disease reflects structural problems in the valves controlling forward blood flow. The PCCN blueprint expects you to differentiate the major cardiomyopathy subtypes and to link each valve lesion to its characteristic murmur and hemodynamic consequence.

The Four Cardiomyopathy Subtypes

Dilated cardiomyopathy (DCM) is the most common form. The ventricular chamber enlarges and thins, contractility falls, and ejection fraction drops — this is the classic substrate for HFrEF. Causes include ischemic injury, viral myocarditis, chronic alcohol use, peripartum cardiomyopathy, and genetic or idiopathic disease. Management mirrors standard systolic heart failure therapy (guideline-directed medical therapy, diuretics, and consideration of an ICD or CRT device once EF remains low despite optimized therapy).

Hypertrophic cardiomyopathy (HCM) features asymmetric thickening of the interventricular septum, which can obstruct left ventricular outflow (HOCM). It is a leading cause of sudden cardiac death in young athletes, often from a fatal dysrhythmia during exertion. Because the thickened septum narrows the outflow tract, anything that reduces ventricular volume or increases contractility worsens the obstruction — diuretics, vasodilators, dehydration, and positive inotropes are avoided. Beta-blockers and non-dihydropyridine calcium channel blockers (verapamil) are preferred because they slow heart rate, prolong diastolic filling, and reduce outflow obstruction.

Restrictive cardiomyopathy is the least common type. The ventricular walls become stiff and non-compliant, impairing diastolic filling while systolic function (EF) often remains near normal. Infiltrative diseases are the classic causes: cardiac amyloidosis, sarcoidosis, and hemochromatosis. Patients present with signs of diastolic heart failure — dyspnea and systemic congestion despite a preserved EF.

Takotsubo (stress) cardiomyopathy — "broken heart syndrome" — is triggered by an intense emotional or physical stressor and produces transient apical ballooning of the left ventricle. It classically mimics an acute STEMI, with chest pain, ST-segment elevation, and elevated troponin, but coronary angiography reveals no significant obstructive disease. Left ventricular function typically recovers within weeks with supportive care.

Ejection fraction categories matter for both diagnosis and drug selection: HFrEF (reduced) is an EF ≤ 40%, HFmrEF (mildly reduced) is 41–49%, and HFpEF (preserved) is ≥ 50%. Restrictive and hypertrophic cardiomyopathy typically fall into the HFpEF/HFmrEF range because the problem is filling, not squeeze — a distinction the exam uses to test whether you understand that a "normal" EF does not rule out significant heart disease.

Valvular Heart Disease

Valve lesions are categorized as stenosis (a narrowed valve that obstructs forward flow) or regurgitation (an incompetent valve that allows backward leak).

Aortic stenosis produces the classic triad of angina, syncope, and heart failure as the outflow obstruction worsens. Auscultation reveals a harsh crescendo-decrescendo systolic murmur radiating to the carotids. Because a stenotic valve fixes cardiac output, hypotension is poorly tolerated and vasodilators must be used cautiously. Transcatheter aortic valve replacement (TAVR) has become a common minimally invasive treatment for symptomatic patients, including those at high surgical risk.

Mitral regurgitation causes a holosystolic (pansystolic) murmur best heard at the apex, often radiating to the axilla. Blood regurgitates backward into the left atrium during systole, eventually causing atrial enlargement, pulmonary congestion, and atrial fibrillation.

Mitral stenosis, most often a late consequence of rheumatic fever, produces a low-pitched diastolic rumble at the apex. The narrowed valve raises left atrial pressure, predisposing to atrial fibrillation and pulmonary hypertension; the elevated left atrial pressure and stasis also raise stroke risk from atrial thrombus.

Aortic regurgitation causes a diastolic decrescendo murmur along the left sternal border. Blood leaks back into the left ventricle during diastole, producing a widened pulse pressure and, over time, left ventricular volume overload and dilation.

Tricuspid regurgitation, though weighted less heavily on the exam than the left-sided lesions, produces a holosystolic murmur at the lower left sternal border that increases with inspiration and is frequently secondary to right ventricular dilation from pulmonary hypertension or left heart failure — a reminder that valve disease on one side of the heart often originates from pressure or volume overload transmitted from the other.

Nursing Priorities

For all valvular and cardiomyopathy patients, the progressive care nurse focuses on matching hemodynamic support to the specific physiology rather than applying one heart-failure protocol universally. A patient with HOCM who receives a standard heart-failure bundle of diuretics and vasodilators can deteriorate rapidly, while a patient with severe aortic stenosis needs careful blood pressure support rather than aggressive afterload reduction. Auscultation findings should always be correlated with echocardiographic data and trended against the patient's baseline, since a new or changed murmur in a previously stable patient — particularly with fever — should prompt evaluation for endocarditis, covered later in this chapter. Recognizing the murmur, the hemodynamic direction of the leak or obstruction, and the resulting chamber stress is the clinical-reasoning pattern tested repeatedly on the PCCN exam.