Hypertrophic Cardiomyopathy (CMH) is a form of cardiomyopathy, characterized by an abnormal and usually asymmetrical, thickening of the heart muscles. CMH is recognized as the most common cause of fatality in young athletes who die during heavy exercise. Myocardial disarray, or a disruption of the normal alignment of the cardiac muscles, is a prominent feature of the condition, along with disturbances in the electric functions of the heart. The most common symptoms of CMH include dyspnea due to increased stiffness of the left ventricle, angina, syncope, fatigue, light-headedness, palpitations, and arrhythmias, which in some patients cause heart failure, followed by sudden death. Although these symptoms are very similar to those of congestive heart failure, treatment strategy for both conditions are entirely different, and therefore, it is important to make a correct diagnosis.
Echocardiography with Doppler ultrasound, ECG, cardiac MRI, transesophageal echocardiogram, and heart monitors can help in the diagnosis of the condition. Treatment is aimed at easing the symptoms of dyspnea, syncope, and angina. Beta blockers or calcium channel blockers are regularly administered. Diuretics reduce the intravascular blood flow, decreasing the desired distension of the left ventricular outflow tract, and hence, need to be avoided. In severe cases, surgical intervention may be required. This may be in the form of septal myectomy, which involves removal of part of the thickened ventricular septum, septal ablation, involving destruction of the thickening by injection of alcohol, pacemaker installation, or implantation of a cardioverter-defibrillator. Prognosis of CMH varies greatly among patients from some patients leading a perfectly normal life, to some with a rapidly worsening course of the disease. Major risk factors for patients succumbing to a sudden heart failure include a young age at first diagnosis, family history of the condition, and the presence of specific mutations in relevant genes.
CMH is believed to result from mutations in one of several genes that result in defects in the protein component of the cardiac muscles. These genes include the Myosin Heavy Chain, Beta), Troponin, Tropomyosin, Cardiac Myosin Binding Protein C, Connectin, and Cardiac Actin, among several other loci. More than 400 mutations have been identified in these genes that lead to the development of CMH; majority of the mutations being observed in the Myosin Heavy Chain 7, Beta and Cardiac Myosin Binding Protein C genes. As mentioned before, disease prognosis depends upon the specific mutation encountered. In addition, recent studies have also shown that an insertion/deletion polymorphism in the gene coding for the Angiotensin Converting Enzyme (ACE) also has an impact on the clinical phenotype of CMH.
Malouf et al. (1985) reported apical hypertrophic cardiomyopathy in father and daughter of a Lebanese Christian family. In both, identical segments of the left ventricle were involved by the hypertrophic process with differing degrees of severity. The parents were not related; an only sib was normal on examination and echocardiogram as were two sisters of the father and their six children.
El-Menyar et al. (2006) analyzed data pertaining to all patients less than 50-years of age, who were hospitalized between 1996 and 2003 with cardiomyopathy in Qatar. Of the total of 132 such patients, 42 were Qataris. Six of these Qatari patients (14.3%) were diagnosed with Hypertrophic Cardiomyopathy (HCM), based on their echocardiographic measurements. HCM was the most common cardiomyopathy after Dilated Cradiomyopathy in this group, and was found to occur in two peaks: one below 15-years of age, and one between 36 and 50-years of age. About 26.8% of the children (between 1 and 15-years) were found to have HCM. The prevalence rate of HCM was calculated as 3.1 per 100,000 of the population (male: female ratio-2:1). HCM was also reported to be associated with Cron's Disease in one of the patients and with Acute Myeloid Leukemia in another.
Obinecheet al., (2002) conducted a study among 151 Emiratis to evaluate the association between left ventricular hypertrophy (LVH) and an insertion/deletion in the second intron of the ANF. Out of the 151, 62 were normotensives with or without LVH, and 89 were hypertensives with or without LVH. There was no history of smoking or alcohol intake in any of the individuals. There was a significant difference in the frequencies if the two alleles between the LVH and no LVH groups, suggesting that the D allele of the ANF gene might be involved in LVH.
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