Dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy: a clinical perspective in 2000

Surgical correction of hypertrophic obstructive cardiomyopathy in patients with simultaneous obstruction of left ventricular midcavity and right ventricular outflow tract

OBJECTIVE

The classic Morrow technique for hypertrophic obstructive cardiomyopathy (HOCM) in patients with simultaneous obstruction of left ventricular (LV) midcavity and right ventricular outflow tract (RVOT) combined with extreme left ventricular hypertrophy, is not effective. A new technique for HOCM surgical correction in patients with severe hypertrophy is proposed.

METHODS

The excision of the asymmetrical hypertrophied area of the interventricular septum (IVS) causing simultaneous midventricular and RVOT obstruction was performed from the conal part of the right ventricle (RV) in the middle part of the right side of the IVS. Conceptually, this approach offers a number of advantages: it affords the excision of the asymmetrically hypertrophied area of the ventricular septum without penetration into the left ventricular cavity, it avoids mechanical damage to the heart conduction system and aortic valve and, for the surgeon, it improves the visual inspection of the area to be resected. Seven patients with the midventricular obstruction of the LV associated with RVOT obstruction [mean New York Heart Association (NYHA) class 3.0] underwent this procedure. The follow-up period was 24.8 ± 11.3 months.

RESULTS

Six patients were free of symptoms (NYHA class I) and one was in NYHA class 2. There were no early or late deaths. The mean value of the echocardiographic intraventricular gradients in the LV decreased from 86.3 ± 9.9 to 10.3 ± 5.3 mmHg, the mean value of the gradients in the RVOT decreased to 44.9 ± 9.6 versus 4.1 ± 1.2 mmHg. Sinus rhythm without the block of the bundle of the right branch was noted in all patients after surgery. No patients needed the implantation of a cardioverter-defibrillator.

CONCLUSION

This technique for the surgical correction of HOCM provides the effective simultaneous elimination of LV midventricular and RVOT obstruction. A major advantage is that injuries, in particular to the conduction system, are easily avoided.

Hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a fascinating disease of marked heterogeneity. Hypertrophic cardiomyopathy was originally characterized by massive myocardial hypertrophy in the absence of known etiology, a dynamic left ventricular outflow obstruction, and increased risk of sudden death. It is now well accepted that multiple mutations in genes encoding for the cardiac sarcomere are responsible for the disease. Complex morphologic and pathophysiologic differences, disparate natural history studies, and novel treatment strategies underscore the challenge to the practicing cardiologist when faced with the management of the hypertrophic cardiomyopathy patient.