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Spring 1997Volume 4, Number 1 |
Heart disease remains, by a considerable margin, the most common cause of death in North America. Given advances in the early management of coronary artery disease and other less prevalent forms of cardiac pathology, the management of patients with chronic heart failure has become an increasingly significant burden on the health care system. Medical therapy continues to improve, with an array of new pharmacologic strategies, and the success of these agents has, in fact, altered the criteria for cardiac transplantation.
Since its introduction as a clinical reality by Shumway and the Stanford group in the late 1960s, heart transplantation has become an established mode of therapy with reliable improvement in survival for the patient who faces imminent mortality. More than 80% of patients survive one year, and for the 60% of patients who live five years, survival approximates that of the age-matched general population. Nevertheless, cardiac replacement with an allograft, mechanical device, or even a xenograft must be regarded as the ultimate end of the spectrum of the treatment of heart failure, beginning on the opposite end with advanced pharmacologic therapy. Along the continuum of increasingly complex and invasive therapies are innovative approaches involving atrioventricular pacing, unilateral right and left ventricular assist devices, and cardiomyoplasty the use of "trained" skeletal muscle that is wrapped around the heart to improve cardiac function. This technique, pioneered by Carpentier, Magovern, Stevenson, and others, has been largely disappointing to the cardiac surgical community.1,2 First, its effect on ejection fraction has been minimal (in the range of 15%) and probably not clinically significant. Second, the operative mortality has been significant and, in the opinion of many clinical investigators, unjustifiably so for NYHA Class II and III patients who can be managed pharmacologically with considerable success in the current era.
Recently, Moreira and Stolf published a timely review of this subject, pointing out two significant new developments in this old story better understanding of the potential mechanisms of benefit from myoplasty and improved surgical results.3 The most compelling new idea regarding mechanism of effect is the concept of the muscle wrap serving as a restraint or "girdle" for the heart, preventing dilatation and permitting ventricular remodeling.3 Moreira and his colleagues report that the improvement in left ventricular function seen with this "external elastic constraint" phenomenon persists at five years.
| Moreira and his colleagues report that the improvement in left ventricular function seen with this "external elastic constraint" phenomenon persists at five years. |
With improvement in anesthetic management and increasing surgical experience, mortality for the operation has been reduced significantly. For example, Moreira's group reports a 30-day mortality of 8.1%. Data from the trial of the new Medtronic stimulatory device reveal an operative mortality <10% in centers where more than 10 procedures have been performed.4 These results tend to override previous widespread concerns that the mortality of the procedure was comparable to that seen with medical therapy for advanced heart failure and suggest that this procedure will now take its place alongside other invasive modalities for treatment of the failing heart. Given the continuing shortage of suitable heart donors, which restricts biologic heart replacement to fewer than 3,000 recipients per year, this procedure will likely become much more commonly utilized. Clinical investigation continues to refine selection criteria.
John Baldwin, MD
Department of Surgery
Baylor College of Medicine
The Methodist Hospital
Houston, Texas
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