HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY ( HOCM) - SURGICAL-MANAGEMENT

Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal, domina nt inherited disease of the myocardium which leads slowly to increasin g subvalvular, septal and left ventricular hypertrophy and deteriorati on of systolic and diastolic left ventricular compliance. Difficult mo lecular-genetic investigations localized genetic defects on different chromosomes. The disease is pathological-anatomically characterized by asymmetric subvalvular (aortic) septal hypertrophy and left ventricul ar outflow tract obstruction resulting in additional left ventricular hypertrophy and dysfunction. Histologically the myocytes are hypertrop hied, exhibit atypical branching (disarray), and there is a high amoun t of interstitial connective tissue. In our biopsy material (from myec tomies) dysplasia could be detected in more than 30% of dysplastic int ramural arteries with partly extential media. These changes may indica te microcirculatory disturbances resulting in arrhythmias, syncopes, s udden death, and anginal pain on the basis of microcirculatory disturb ances and scar development. Today the discussion of DDD-pacemaker ther apy has resumed, but one must wait for definite results, especially in patients in whom surgical treatment seems to be the best choice. The indication for surgical treatment, which usually is transaortic subval vular myectomy (Morrow) and modifications, is very restrictive. Only p atients in clinical degree III (NYHA) after long-term medical treatmen t are candidates for surgery. In some mainly younger patients the indi cation in lower clinical degrees was accepted because of a family hist ory with sudden death and personal experience of syncope, life-threate ning tachycardia, or after resuscitation. In the period 1963 to 1994 4 66 patients were operated upon. The mean age was 44.9 years (range 3 m onths to 82 years). Total early mortality was 4.9% (n = 23). For trans aortic subvalvular myectomy alone it was 3.2% (n = 11), while in the c ase of additionally necessary cardiac procedures in 127 patients, it r ose to 9.4% (n = 12 deaths). The preoperative clinical classification showed 14 patients in class II with no deaths, 435 patients in class I II with 13 deaths (3%), and 12 patients in class IV with 5 early death s (41.7%). All patients in class V (cardiogenic shock) (n = 5) died in tra- or early postoperatively. Intraoperative measurements of the syst olic gradient between left ventricle and aorta show a significant redu ction after transaortic subvalvular myectomy at rest and after provoca tion. A survey of the recent literature indicates a very similar impro vement of the results in regard to early, late, and yearly rate of let hality after surgery, which is considerably less than after medical th erapy alone. Further investigations are necessary for additional molec ular genetic and ultrastructural classification of the myocardial proc ess for which material from our myectomized myocardium may be helpful. Other questions concerning family history and penetrance of genetic v ariations need to be settled. Clinical pre- and intraoperative judgeme nt could be improved by echocardiographic techniques and coloured flow doppler sonography, methods which allow a close non-invasive follow-u p of the patients after surgery. Despite the fact that the transaortic subvalvular extended myectomy (combined Morrow-Bigelow technique) is not a curative but only a palliative procedure, the surviving patients benefit through clinical improvement, reduction of symptoms and bette r physical exertion for many years. The reason is amelioration of the systolic and diastolic function of the left ventricle, as a result of a considerable reduction in the gradient and resection of hypertrophie d myocardium, as well as the reduced amount of mitral regurgitation.