Hans-Erik Hansson

Decreased Blood Loss After Cardiopulmonary Bypass using Heparin-Coated Circuit and 50% Reduction of Heparin Dose

In a randomized, double-blind study of patients undergoing elective coronary artery grafting, the effect of heparin-coated circuit combined with 50% reduction of systemic heparin bolus was investigated. Ten patients comprised group HC (heparin-coated) and ten group C (controls). The mean total doses of heparin were 172 IU/kg in group HC and 416 IU/kg in group C and the respective protamine doses were 0.96 and 3.96 mg/kg (both p < 0.001). Activated clotting times during cardiopulmonary bypass were significantly shorter in group HC, and both intra- and postoperative bleeding was significantly less than in group C (7.7 vs. 11.7 ml/kg, p = 0.036, and 6.9 vs. 9.7 ml/kg, p = 0.004). Hemoglobin loss via the drains was 22.5 g in group HC and 43.7 g in group C (p < 0.005). Hemolysis at the end of bypass was significantly greater in group C. Apart from one perioperative myocardial infarction in group HC the postoperative course was uneventful. Use of a heparin-coated circuit is concluded to permit complication-free reduction of heparin and protamine doses and to decrease both intra- and postoperative bleeding, which may favorably influence the outcome of coronary artery grafting.

Heparin-coated cardiopulmonary bypass circuits and 25% reduction of heparin dose in coronary artery surgery—a clinical study

Cardiopulmonary bypass with systemic heparinization causes trauma to blood cells and coagulation defects. Artificial surfaces could be coated by end-linkage binding of heparin (Carmeda Bioactive Surface, CBAS). Use of such surfaces during cardiopulmonary bypass in animals resulted in less postoperative blood loss and better preservation of blood cells. In this study heparin-coated circuits were employed during coronary artery grafting in 7 patients (Group HC). Concomitantly, the heparin dose was reduced by 25% and an activated clotting time (ACT) of 300 sec was accepted. Additional 7 patients were operated with standard circuits (Group C), requiring ACT above 400 sec with normal doses of heparin. There were no thromboembolic complications in Group HC. The postoperative bleeding was generally low and without significant intergroup differences. Coagulation parameters displayed significantly lower ACT and anti-Factor Xa during bypass in Group HC. A tendency towards less blood cell trauma was observed with heparin-coated circuits. The protamine dose could be reduced by 50%, which significantly reduced the protamine/heparin quotient. This study indicates that routine cardiopulmonary bypass could be performed safely with heparin-coated circuits and reduced intravenous doses of heparin and protamine. It is suggested that the use of heparin-coated circuits may lead to less blood cell trauma.

Myocardial high-energy phosphates, lactate and pyruvate during moderate or severe normothermic ischemia in rat hearts perfused with phosphoenolpyruvate and atp in cardioplegic solution

Rat hearts were subjected to normothermic ischemia for 15 min (group I) or 30 min (group II). During the ischemic period the hearts were perfused twice with cardioplegic solution supplemented with 14.4 mM phosphoenolpyruvate (PEP) and/or 0.067 mM adenosine triphosphate (ATP), and at the end of ischemia they were freeze-clamped. The myocardial ATP content in group I fell to about 55% of normal values except in hearts supplemented with only PEP, which showed greater reduction. In group II the ATP fell to only about 5% of normal values, without significant differences between the subgroups Hearts supplemented with PEP alone or with combined PEP-ATP showed significantly higher levels of pyruvate than in hearts with only ATP supplementation or control hearts. The study thus demonstrated clear difference in ATP content between moderate and severe ischemic trauma. The high pyruvate levels after PEP supplementation indicate formation of pyruvate without concomitant lactate increase.

METABOLIC AND FUNCTIONAL EFFECTS OF CREATINE PHOSPHATE IN CARDIOPLEGIC SOLUTION Studies on Rat Hearts during and after Normothermic Ischemia

Creatine phosphate is a precursor molecule for ATP synthesis, even under ischemic conditions. We investigated its functional and metabolic effects when added to cardioplegic solution. Rat hearts were subjected to normothermic ischemia for 15 or 30 min and then freeze-clamped. During ischemia there was gradual reduction of high-energy phosphates, but the hearts with creatine phosphate supplement showed higher myocardial content of ATP and of the creatine compound. Other hearts, subjected to 20 min of ischemia, were reperfused with blood for 40 min. Creatine phosphate supplementation resulted in better left ventricular isovolumic work during spontaneous activity, but in paced activity (400 beats/min) no significant differences were seen. After reperfusion, supplemented hearts showed a tendency to higher levels of ATP and creatine phosphate. In all three groups the hearts with cardioplegic supplement had significantly increased myocardial content of pyruvate without proportional lactate increase. The results indicate that creatine phosphate may be an effective constituent in cardioplegic solution.

Interrelated effects of nucleoside mono- and triphosphates and phosphoenolpyruvate on rat hearts subjected to cardioplegic arrest at normothermia

Supplementation with phosphoenolpyruvate (PEP) and ATP was previously found to enhance the protective effect of potassium cardioplegia on rat hearts subjected to extensive ischemic trauma (30 min at 37 degrees C) in the paracorporeal rat heart model. In the present experiments, the ischemia time was reduced to 20 min (37 degrees C). Ventricular work after ischemia was best in control rats with potassium cardioplegia only. Supplementing the cardioplegic solution with PEP and ATP (group I) resulted in significantly reduced postischemic ventricular work and increased efflux of the creatine kinase isoenzyme MB (CK-MB). The same result was obtained when adenosine monophosphate (AMP) was added to the supplementation (group II). When guanosine monophosphate (GMP) was added instead of AMP (group III), the negative effects of PEP and ATP in the cardioplegic solution were partly abolished. Plain potassium cardioplegia, without additives, nevertheless gave the best results. There were no significant intergroup differences in the myocardial content of adenine nucleotides. The results contrasted with those in the previous study of more protracted ischemic trauma (30 min at 37 degrees C) and possible explanations are discussed.

Mitral valve prosthetic implantation with preservation of native mitral valve apparatus.

To avoid postoperative morbidity and mortality often associated with left ventricular dysfunction after mitral valve replacement (MVR) for chronic mitral insufficiency, reconstruction or preservation of the native mitral valve apparatus may be attempted during mitral prosthetic implantation (MPI). The effects of mitral surgery on heart function, studied with echocardiography and radionuclide angiography, were compared in seven patients with MPI (study group) and five with MVR (control group) who underwent complete preoperative, early postoperative and 3-6 months follow-up examinations. Preoperatively there was significant intergroup difference only in right ventricular ejection fraction measured at radionuclide angiography, which was lower in the MPI group (p < 0.05). At follow-up the MPI group had improved as regards this fraction (p < 0.005) and stroke volume index (p < 0.05). The number of patients with improved NYHA class at follow-up was significantly greater in the MPI group. Our preliminary experience with preservation of the native mitral valve apparatus thus suggests that the method offers haemodynamic advantages for postoperative right ventricular function.

Pericarbon Pericardial Valve Prosthesis: Midterm Results of the Aortic Valve Replacement

This clinical study was undertaken to verify the encouraging results of experimental studies regarding a new pericardial bioprosthesis. From May 1989 to November 1993, 204 patients underwent an aortic valve replacement with the Pericarbon® (Sorin Biomedica Cardio S.p.A., Saluggia, Italy) prosthesis. A follow-up was 100% complete and extended to 65 months (total 408 patient-years, average 2.0 ±1.4 years). Mean age at the operation was 75.1 ± 5.5 years and 96% were in NYHA clinical stage III or IV. There were 86 men and 118 women; 73 patients had an isolated aortic valve disease, 131 had a concomitant cardiosurgical procedure (coronary artery bypass grafting in 106 patients). The operative mortality (30-day mortality) rate was 11.8% (24/204). There were 24 late deaths (5.9 ±1.2% patient-year). The actuarial probability of survival was 68 ±5% at 5 years. Four patients died of valve-related causes (one thromboembolic complica tion, two endocarditis, one anticoagulant-related hemorrhage). Actuarial rate of freedom from valve-related death was 95 ±3% at 5 years. Valve-related morbidity included seven thromboembolic episodes (1.7% patient-year), four anticoagulant-related complications (0.9% patient-year), three endocarditis (0.7% patient-year) and one reoperation (0.2% patient-year). After 5 years freedom from thromboembolic events was 83 ±7%, from anticoagulant-related hemorrhage 96 ±2%, from endocarditis 97 ±2%, and from reop eration 99 ± 1 %. Echocardiographic study performed in 30 patients showed a paraprosthetic leak in four patients, a central leak in two, and cusp thickening in another three. The clinical data showed that the Pericarbon prosthesis has valve-related morbidity. The echocardio graphic results suggest that the prosthesis can undergo a pathologic process during the first 5 years after implantation. This makes it necessary to continue the follow-up and include the larger number of patients in the echocardiographic investigation.