What is cardiomyopathy? What are the main symptoms and manifestations of cardiomyopathy?

Cardiomyopathy is a myocardial disease of unknown cause, which does not include specific cardiomyopathy with clear etiology or secondary to systemic disease. So what are the symptoms of cardiomyopathy?

Main symptoms

① Dyspnea often occurs after exertion. It is caused by decreased left ventricular compliance, increased end-diastolic pressure, and subsequent increased pulmonary venous pressure, resulting in pulmonary congestion. Mitral regurgitation associated with ventricular septal hypertrophy can aggravate pulmonary congestion.

② Precordial pain, which often occurs after fatigue and is similar to angina pectoris, but may be atypical. It is caused by increased oxygen demand of the hypertrophic myocardium and relatively insufficient blood supply to the coronary arteries.

③ Fatigue, dizziness and fainting often occur during activities. This is due to the increased heart rate, which further shortens the diastolic period of the left ventricle, which already has poor diastolic filling, aggravating the inadequate filling and reducing cardiac output. When active or emotionally excited, the sympathetic nerves increase the contraction of the hypertrophic myocardium, aggravate the outflow tract obstruction, and cause a sudden drop in cardiac output, resulting in symptoms.

④ Palpitations due to decreased heart function or arrhythmia.

⑤ Heart failure is more common in late-stage patients. Due to decreased myocardial compliance, the ventricular end-diastolic pressure increases significantly, followed by increased atrial pressure, and is often accompanied by atrial fibrillation.

Common signs

①The boundary of cardiac dullness expands to the left. The apex beat is displaced to the lower left, with a lifting impulse. Or there may be an apical doublet, a beat produced when the atria eject blood into the less compliant ventricles and is touched before the apical beat.

② A mid-systolic or late-systolic ejection murmur can be heard on the inner side of the apex at the lower left edge of the sternum. It propagates toward the apex rather than the base of the heart and may be accompanied by systolic tremor, which is seen in patients with ventricular outflow tract obstruction. Any measures that increase myocardial contractility or reduce cardiac load, such as digitalis, isoproterenol (2 μg per minute), amyl nitrite, nitroglycerin, Valsalva maneuver, after physical labor or premature beats, can enhance the murmur; any measures that weaken myocardial contractility or increase cardiac load, such as vasoconstrictors, beta-blockers, squatting, and clenching fists, can weaken the murmur. In about half of patients, a murmur of mitral regurgitation can also be heard.

③The second sound may be abnormally split, which is caused by obstruction of left ventricular blood ejection and delayed closure of the aortic valve. The third tone is common in patients with mitral regurgitation.

"ECG manifestations"

①ST-T changes are seen in more than 80% of patients. Most of them have normal coronary arteries. A few patients with localized myocardial hypertrophy in the apical area have huge inverted T waves due to abnormal coronary arteries.

②Signs of left ventricular hypertrophy are seen in 60% of patients, and their presence is related to the degree and location of myocardial hypertrophy.

③The presence of abnormal Q waves. The deep but not broad Q waves in leads V3, V5, aVL, and I reflect asymmetric ventricular septal hypertrophy and should not be mistaken for myocardial infarction. Sometimes Q waves may also be present in leads II, III, aVF, V1, and V2. Their occurrence may be caused by irregular and delayed conduction of impulses in the subendocardial and intramural myocardium after left ventricular hypertrophy.

④ Abnormal left atrial waveform may be seen in 1/4 of patients.

⑤Some patients have concurrent preexcitation syndrome.

"Echocardiographic findings:"

① Asymmetric ventricular septal hypertrophy, the ratio of the ventricular septum thickness to the left ventricular posterior wall thickness is greater than 1.3:1. This sign was given more attention in the past, but now it is found that it can also be seen in other diseases such as hypertension and aortic valve stenosis. It is more useful to measure the degree of left ventricular thickening using a two-dimensional method.

②The anterior leaflet of the mitral valve moves forward during systole.

③The left ventricular cavity is reduced and the outflow tract is narrowed.

④Left ventricular diastolic dysfunction, including decreased compliance, prolonged rapid filling time, and prolonged isovolumetric relaxation time. The use of Doppler technology can help understand the origin of the murmur and calculate the pressure difference before and after the obstruction.