Vitamin E action on oxidative state, endothelial function and morphology in long-term myocardial preservation.

This study assesses the effects of a vitamin E analogue, Trolox, on the oxidative state, endothelial function and morphology in experimental heart transplantation. Heterotopic heart transplantation was carried out in pigs: untreated after 2 and 24 hours of ischemia and treated with Trolox after 24 hours of ischemia. Prolonged preservation of donor hearts was achieved with continuous perfusion and University of Wisconsin solution, in which acid-base balance and enzymes were determined during the procedure. In recipients, hemodynamic and biochemical parameters were determined at baseline and during reperfusion. Trolox diminished the pH of the preservation solution (p<0.01), the left ventricle of the transplanted heart recovered a systolic pressure equaling that of the 2h group and higher than that of the untreated 24h group (p<0.01), the antioxidant levels were not decreased and the glutathione reductase level was maintained throughout the first part of reperfusion. In this group also there was a direct correlation between the concentration of this enzyme and the antioxidant levels (p<0.001). Although the endothelin concentrations increased, the change was less marked in the Trolox group than in the untreated 24h group (p<0.01). Morphologically, mitochondria and myocardial vessels presented a normal structure in the Trolox group, and interstitial edema, inflammatory infiltrate and contraction bands were less prominent than in the untreated group. All these effects indicate that Trolox protected the transplanted heart, at least partially, against ischemia-reperfusion injury.

Calcium-supplemented University of Wisconsin solution in long-term myocardial preservation.

The purpose of this study was to assess the effects of the addition of calcium to University of Wisconsin solution in long-term myocardial perfusion. In a heterotopic heart transplantation model, performed in pigs, the donor heart was preserved for 24 hours by means of continuous perfusion in this solution, without (24hUW group) or with calcium, 2.4 mmol/L (24hUW+Ca). During this period, the oxygenation and pH of the solution were measured, as were the calcium and lactate concentrations and enzyme release. After two hours of reperfusion, samples were collected from both ventricles for the morphological study. In the control group, there were no signs that reperfusion had triggered the calcium paradox. The addition of this cation to the preservation solution improved the intercellular junction integrity but, at the same time, favored intracellular calcium overload. This is manifested by increased enzyme release during preservation (LDH: 242+/-95 vs 140+/-25; CK: 668+/-371 vs 299+/-83 (U/L). p<0.01 in both cases) and signs of ventricular contracture: hardness and stiffness were significantly more prominent than in the group without calcium supplementation. Moreover, in comparison with the control group, the structural morphology of 24hUW+Ca is characterized by the more prominent and extensive presence of contraction bands and disorganized actin structure. Thus, under the experimental conditions employed in this study, we consider the addition of calcium to Wisconsin solution to be unadvisable.

[Aortic root homograft in the surgical treatment of aortic valve disease with dilated ascending aorta]. / Homoinjerto de raíz aórtica para el tratamiento quirúrgico de las afecciones de la válvula aórtica con aorta ascendente dilatada.

INTRODUCTION AND OBJECTIVES: Patients with aortic valve disease and a dilated ascending aorta are usually treated with a composite graft comprising a valve and conduit. We review here the results of treatment with an aortic root homograft as a valid alternative. PATIENTS AND METHOD: Twenty-two consecutive patients with a mean age of 64.8 (8.8) years were studied. Mean ascending aorta dilation was 54.55 mm, aortic valve insufficiency was present in 16 patients, and a combined lesion was present in 6. In all cases a cryopreserved aortic root homograft was used to replace the aortic valve and ascending aorta. In 9 cases a Dacron conduit was used beyond the sinotubular junction to restore continuity between the homograft and the native aorta. RESULTS: All patients survived surgery. One patient had postoperative systemic inflammatory response syndrome and one patient was re-explored for excessive bleeding. Mean duration of follow-up was 12.1 months (range 2-36 months). No patient was given anticoagulants, and one had an early transient cerebrovascular accident followed by complete recovery. At one month postsurgery the left ventricular systolic (P<.001) and diastolic (P<.009) diameters had decreased significantly on echocardiography, and these decreases persisted throughout follow-up. The caliber of the ascending aorta was normal in all patients (< or =30 mm) except one. CONCLUSIONS: Aortic root homografts are a valid alternative in the treatment of aortic valve disease with ascending aorta dilation. The main advantages of this therapy are that permanent anticoagulation is not needed, and that left ventricular dimensions recover rapidly.