A. Causes
Cardiac hypertrophy can be caused by the following processes.
1. Pressure overload due to clinical conditions such as aortic stenosis, hypertension, pulmonary stenosis, coarctation of aorta
2. Volume overload due to clinical conditions such as mitral valve regurgitation, aortic valve regurgitation, large ventricular septal defects, and patent ductus arteriosus
3. Reactive processes that may occur following obstruction to myocardial cells such as with myocardial infarction, myocarditis, dilated cardiomyopathy, and other causes of myocardial cell loss
4. Diseases that primarily affect the myocardial muscle such as hypertrophic cardiomyopathy (see Figure 1 in the chapter entitled cardiomyopathy)
5. Physiologic hypertrophy as seen in athletes (see the chapter Athletes and Sudden Cardiac Death).
B. Complications
Left ventricular hypertrophy is associated with a significant increase in the incidence of heart failure, myocardial infarction, arrhythmias, and sudden death. In the presence of left ventricular hypertrophy, the left atrium tries to pick up some of the stretch to aid the ventricle. The thin-walled weak chamber has very little to offer except that fibrosis occurs during the course of left atrial hypertrophy and with alterations the conducting tissue which culminates in atrial fibrillation. Chronic hypertension that persists without adequate treatment for more than 10 years is a common cause of mild left atrial hypertrophy and atrial fibrillation, which slowly predispose a patient to cardiac embolization to the brain causing stroke. Massive hyper¬trophy (>30 mm) in patients with cardiomyopathy is associated with sudden death.