IS Case 277: Hypertrophic cardiomyopathy
Imaging Sciences URMC 2009
Publication Date: 2009-08-05
Cardiac MR demonstrates concentric left ventricle hypertrophy with thickest portion at the anteroseptum measuring 2cm. Left ventricle has hyperdynamic ejection fraction of 71%. There is also diffuse patchy enhancement of the left ventricle consistent with hypertrophic cardiomyopathy.
Hypertrophic cardiomyopathy (HCM) is a nondilated hypertrophy of the left ventricle in the absence of cardiac or systemic disease that could produce left ventricular hypertrophy. In asymmetric septal hypertrophy, the most frequently occurring subtype of HCM, the basal septum of the left ventricle is disproportionately thickened. In apical hypertrophy, however, another subtype of HCM, the apical portion is markedly thickened. Since the treatment plan is different for each subtype of HCM, the accurate diagnosis for the extent and severity of disease is important.
The diagnosis of HCM can be made with echocardiography, cardiac catheterization, and cardiac angiography. Compared with other modalities, cardiac magnetic resonance imaging has many inherent advantages, such as excellent characterization of soft tissue, clear depiction of natural contrast between the blood and cardiovascular structure, good capability of creating images with direct multiple planes, and noninvasiveness.
HCM is relatively common, with an estimated prevalence of 0.2% in adults. Recent studies among children suggest a lower incidence for disease expression beginning in childhood, with a rate of 3-5 cases per 1 million children. Morphologic evidence of disease is found using echocardiography in approximately 25% of first-degree relatives of patients with HCM, consistent with variable expressivity.
Patients with HCM may be asymptomatic. Symptoms can include sudden cardiac death, dyspnea, syncope, presyncope, angina, palpitations, orthopnea, paroxysmal nocturnal dyspnea, congestive heart failure, and dizziness.
Treatment for HCM includes implantable cardioverter-defibrillator for HCM patients at high-risk. It has the potential to alter the disease course by automatically sensing and terminating lethal disturbances of heart rhythm, often in young people with little or no symptoms. Should medical treatment fail, surgical options include septal myectomy operation, in which the surgeon removes a small amount of muscle from the upper part of the septum. At experienced centers, myectomy has low operative mortality, and most patients experience long-lasting improvement in their capacity for physical activity. This is due to the return of pressures within the heart to the normal range and the elimination of mitral valve leakage. Alternative treatment includes septal ablation technique in which a small amount of absolute alcohol is introduced into a small coronary artery branch for the purpose of destroying heart muscle in the septum, leading to reduced obstruction and symptoms. Alcohol ablation and septal myectomy have similar risks. However, ablation is a new technique, follow-up of patients is relatively brief, and there is some concern that the permanent scar produced within the septum could eventually generate serious rhythm disturbances and actually increase risk for sudden death.
- Bogaert J, Dymarkowski S, Taylor AM, Editors. Clinical Cardiac MRI. Springer, 2005.