[Hypertrophic obstructive cardiomyopathy: surgical treatment and results]

The natural history of hypertrophic obstructive cardiomyopathy is characterized, in particular, in younger patients by sudden cardiac death, in the majority of patients by progressive congestive heart failure [14, 26, 27, 33-36]. With the aid of beta-adrenergic receptor blockers, calcium channel blockers and antiarrhythmic agents the clinical outlook for most of the patients can be improved [17, 19, 23, 28]. Patients who do not respond to medical treatment can be regarded as possible candidates for surgical revision of the left ventricular outflow tract. In consideration of surgical treatment, two morphologic and hemodynamic forms of the disease must be differentiated: the typical subaortic muscular hypertrophy in the region of the outflow tract and the atypical, more mid-ventricular muscular hypertrophy with systolic entrapment of a distal portion of the ventricle in which frequently a typical subaortic hypertrophy also may be present [15, 43]. As a result of septal subvalvular hypertrophy which may substantially compromise left ventricular ejection during systolic contraction, in hypertrophic obstructive cardiomyopathy there is a deviation of the left ventricular major axis, dyscoordination in the sequence of contraction, hypertrophy of the left ventricular walls, diminished diastolic compliance and, to a varying extent, mitral regurgitation. Diagnostically useful findings are a mid-systolic murmur at the aortic valve, bisferiens carotis pulse, systolic pressure gradient between the left ventricle and the aorta and a postextrasystolic paradoxical pressure response. Echocardiographically, asymmetric septal hypertrophy, systolic anterior motion of the anterior mitral valve leaflet, premature mid-systolic closure of the aortic valve and an enlarged left atrium will be detected. Surgical intervention is indicated for patients with class III clinical symptoms (NYHA) not amenable to medical treatment and pressure gradients between left ventricle and aorta, at rest or postextrasystolically, in excess of 50 mm Hg. An overview of the variety of surgical approaches and procedures employed for hypertrophic obstructive cardiomyopathy is provided by Table 1. From initial attempts to eliminate the outflow tract obstruction by myotomy, the subvalvular myectomy was developed in which an about 1 cm wide section of muscle is resected; this procedure can be carried out from a transaortic, transatrial or transventricular approach [4, 9, 21, 22, 24, 38, 39, 47]. Under the assumption that the anterior motion of the anterior mitral valve leaflet contributes to systolic obstruction, some authors recommended reconstructive procedures or replacement of the mitral valve.(ABSTRACT TRUNCATED AT 400 WORDS)