Hypertrophic Obstructive Cardiomyopathy

Abstract

Background: Hypertrophic cardiomyopathy (HCM) is caused by mutations in a number of genes. Its prevalence is 0.2% to 0.6%.

Methods: This review is based on publications retrieved by a selective literature search and on the authors' clinical experi- ence.

Results: 70% of patients with HCM suffer from the obstructive type of the condition, clinically characterized by highly dynamic and variable manifestations in the form of dyspnea, angina pectoris, and stress-dependent presyncope and syn- cope. Younger patients are at particular risk of sudden cardiac death; thus, all patients need not only symptomatic treatment, but also risk assessment, which can be difficult in individual cases. Left ventricular obstruction, which usually causes symptoms, is treated medically at first, with either a beta- blocker or verapamil. If medical treatment fails, two invasive treatments are available, surgical myectomy and percu- taneous septum ablation. Both of these require a high level of expertise. If performed successfully, they lead to sustained gradient reduction and clinical improvement. Septum ablation is associated with low perioperative and peri-interventional mortality but necessitates permanent pacemaker implantation in 10-20% of patients.

Conclusion: In the absence of evidence from randomized comparison trials, a suitable method of reducing the gradient should be determined by an HCM team in conjunction with each individual patient. Important criteria for decision-making include the anatomical findings and any accompanying illnesses.

Figure 1

Schematic representation of septal myectomy, with access via the mitral valve in almost all cases (a), in hypertrophy of the ventricular septum (IVS) with subaortic obstruction (blue arrow in b), leading to mitral insufficiency (green arrow) of variable degree. Sparing the cardiac conduction system, septal myocardium is resected, depending on the area of hypertrophy and extending if necessary as far as the level of the papillary muscles, to an extent (dotted lines in a and b) sufficient to eliminate the obstruction, retaining septal thickness of 1 cm. LA = Left atrium, LV = left ventricle

Figure 2

Steps in echocardiographically guided septal ablation (from [6]) a) Initial angiogram of the left coronary artery showing the targeted septal branch (red arrow) and the temporary pacemaker probe (green arrow) b) Modified initial four-chamber view echocardiogram with systolic contact between the mitral valve and the septum (green arrow) c) The echocardiographic contrast medium depot in the subaortic segment of the ventricular septum at the level of the contact point between the mitral valve and the septum (green arrow) d) Occluded septal branch (red arrow) following balloon removal 10 min after the final injection of alcohol without damage to the anterior interventricular branch

eFigure:

Echocardiography in a patient with HOCM: apical four-chamber view in systole. a) With SAM (arrow) and in parasternal longitudinal plane in diastole; b) hypertrophic interventricular septum (IVS) with narrow left ventricular cavity (LV) HOCM, hypertrophic obstructive cardiomyopathy; LA, left atrium; LVPW, left ventricular posterior wall; RA, right atrium; RV, right ventricle; SAM, systolic anterior motion