Anabolic Steroids (Metenolone) Improve Muscle Performance and Hemodynamic Characteristics in Cardiomyoplasty

The loss of force and mass in the conditioned latissimus dorsi muscle are principal reasons for the poor improvement in hemodynamic functioning attained by cardiomyoplasty. Using 24 sheep, we investigated the effect of anabolic steroids on the hemodynamic, histologic, and myophysiologic characteristics in the setting of cardiomyoplasty. In 12 of the animals (group A), the latissimus dorsi muscles were electrically conditioned with an Itrel pulse generator; in the remaining 12 animals (group B), the electrical conditioning was combined with the administration of an anabolic hormone (metenolone; 100 mg/week). The hemodynamic measurements were performed during isolated perfusion of the subclavian artery (maintenance of pressure in the muscles), while all other circulation variables were held at the exact and reproducible value of zero by inducing ventricular fibrillation. Maximum force and muscle mass showed a significant increase in group B (maximum force: group A, 4.23 ± 0.55 kp, and group B, 6.0 ± 3.14 kp; muscle mass: group A, +11.07% ± 1.06%, and group B, +79.9% ± 40.8%). The ratio of type I to type II fibers after 12 weeks was 65.2% to 34.8% in group A and 96.7% to 3.3% in group B, as opposed to 19.9% to 80.1% in the control group. No side effects of the anabolic steroids were observed during the experiment. In the hemodynamic studies, we were able to demonstrate a further significant increase in the left ventricular pressure, fractional fiber shortening value, ejection fraction, stroke volume, cardiac output, and stroke work when using conditioned latissimus dorsi muscles that were additionally treated with metenolone. In our reproducible heart failure model, the administration of anabolic steroids led to an acceleration of the fast-to-slow transformation, an increase in the force capacity and muscle mass of the conditioned latissimus dorsi muscles, as well as an improvement in hemodynamic functioning, while the pharmacologic effects remained confined to the chronically stimulated muscle. It seems likely, therefore, that anabolically conditioned latissimus dorsi muscles can help cardiac insufficiency in two ways. On the one hand, they can produce a significant direct increase in contractility. On the other hand, the considerable increase in thickness can be expected to cause a reduction in wall tension and in myocardial oxygen consumption according to Laplaceʹs law.