Heat from an implanted power source is mainly dissipated by blood perfusion.

Heat dissipation and its effects on tissue and blood interfaces are common problems associated with the development and increased use of artificial hearts, because all of the implantable actuators for artificial hearts generate waste heat due to inefficiencies of energy conversion. To determine the mechanisms of heat dissipation from artificial hearts, heated disks producing constant heat fluxes of 0.08 watts/cm2 were implanted adjacent to the left lung and the latissimus dorsi muscle in calves for 2 weeks, 4 weeks, and 7 weeks. At the end of each experiment, a series of acute studies was performed in which blood perfusion to the heated tissue was decreased or stopped to observe the contribution of blood perfusion to heat dissipation. The cooling effect of ventilation was also examined to determine its relative contribution to heat dissipation in lung tissue by decreasing the minute ventilation volume. The importance of blood perfusion for heat dissipation was demonstrated by the temperature rise after cessation of blood perfusion to the heated tissue. The contribution of ventilation to heat dissipation in the heated lung tissue was minimal. Contribution of total blood perfusion to heat dissipation was increased with time in the muscle tissue, which has relatively low resting blood perfusion, but not in the lung tissue, which has relatively high blood perfusion. In the heated muscle tissue, the in vivo adaptive response to chronic heat was functionally shown by the increased perfusion. In conclusion, blood perfusion was the main mechanism of heat dissipation from tissues that were adjacent to an implanted power source.

Anatomic fitting studies of a total artificial heart in heart transplant recipients. Critical dimensions and prediction of fit.

Anatomic fitting studies of the Cleveland Clinic-Nimbus total artificial heart were performed in 33 patients undergoing heart transplantation. The pump fit in the pericardial space in 20 men (80%) and 4 women (50%). There was no significant difference between the Fit and Non-Fit groups in external chest dimensions. Among 42 intrathoracic dimensions, the distance from the center of the mitral valve to the diaphragm (Fit: 5.6 +/- 2.2 cm, Non-Fit: 3.6 +/- 0.4 cm, p < 0.00001) and the distance from the caudal end of the pulmonary valve to the diaphragm (Fit: 9.4 +/- 1.6 cm, Non-Fit: 6.3 +/- 0.8 cm, p < 0.0001) were the most critical. To predict anatomic fit, an index (A x B x C) was obtained from chest X-ray measurements (A, the craniocaudal distance from the dorsal region of the 8th left rib to the left diaphragm; B, the maximum left chest width; and C, the maximum anteroposterior sternum-vertebrae dimension). The pump fit in 88.5% of the patients with an index above 1200 cm3, whereas it fit in only 14.3% of the patients with an index below 1200 cm3 (p < 0.001). This index was an easily obtainable, good predictor of anatomic fit.

Platelets are deposited early post-operatively on the leaflet of a mechanical heart valve in sheep without post-operative anticoagulants or antiplatelet agents. A scanning electron microscopic observation of the pyrolytic carbon surface in a mechanical heart valve.

Pyrolytic carbon has been used for mechanical heart valves as a thromboresistant, wear resistant, and fatigue resistant material. Thrombosis and thromboembolism, however, remain major mechanical heart valve associated complications and may frequently occur during the early post-operative period. In depth morphologic studies on blood-pyrolytic carbon surface interactions are limited. The purpose of this study was to evaluate the blood compatibility of the pyrolytic carbon surface of St. Jude Medical mechanical heart valves that were implanted in the mitral position of sheep without the administration of post-operative anticoagulants or antiplatelet agents for 2, 4, and 6 weeks. Almost the entire leaflet and orifice ring surfaces were observed by scanning electron microscopy. Although the surfaces appeared clean macroscopically, when observed by electron microscopy, the surface were mottled, mainly by solitary platelets and aggregations. There were only a few leukocytes or red blood cells observed. No fibrin clots were observed on the leaflets. The density of platelet deposition was higher in the vicinity of the pivots and near the edges of the leaflets. The sizes of the platelet aggregations decreased with longer duration. The outer surfaces of the pivot guards were covered by various amounts of deposition composed of platelet aggregations and thrombi. Thus, the administration of antiplatelet agents is recommended during the early post-operative period after mechanical heart valve implantation.

Early and late results with combined mitral and aortic valve replacement.

From February 1977 to January 1993, a total of 52 patients have undergone combined mitral and aortic valve replacement (MAVR) at the Fukuoka University Hospital. The ages at operation ranged from 35 to 72 years (mean, 55.3 years) for 16 males and 36 females. Twenty-five patients received two bioprosthetic valves (group BB); 6 received a combination of bioprosthetic valve and mechanical valve (group BM); and 21 received two mechanical valves (group MM). The previous intra-cardiac operations were performed on 24 patients (46.2%). The purpose of this study was to learn about the long-term clinical results of MAVR and to analyze the difference among three groups. Seven patients died within 30 days of operation or during initial hospitalization (early mortality: 13.5%). Two patients died at late period, 5.8 years and 6.9 years after operation, respectively (linearized occurrence rate: 0.9%/pt-yr). Patient survival rate including operative death was 82.9% +/- 5.7% at 5 years and 79.0% +/- 6.7% at 8 years in the total number of patients. Thromboembolism occurred in 2 patients in group MM (0.9%/pt-yr). Anticoagulant-related hemorrhage occurred only in 1 patient (0.4%/pt-yr in overall), in whom two bioprosthetic valves were implanted (group BB), in spite of being in good control with anticoagulants. No infective endocarditis was encountered in any patients during any of the periods. Reoperations were performed in 7 patients (3%/pt-yr in overall), 5 in group BB and 2 in group MM. Percentage freedom from reoperation was 86.4% +/- 5.9% at 5 years and 78.2% +/- 7.7% at 8 years in all. There was no difference among the three groups. Percentage freedom from overall morbidity and mortality was 74.5% +/- 6.9% at 5 years in all. Group MM showed higher morbidity and mortality at 8 years than other groups, but there were no significance (MM: 52.4% +/- 17.6%, BB: 76.5% +/- 9.5%, BM: 83.3% +/- 15.2%). We conclude that there were no significant differences in long-term results of NAVR which consisted of the following combinations of prostheses such as BB, BM, and MM. Redoing MAVR with New York Heart Association functional class IV and emergency cases were considered as in-hospital risk factors.

[Treatment of postoperative mediastinitis using an omental pedicle flap].

Four patients with postoperative mediastinitis who were treated by omentopexy at the Fukuoka University Hospital between 1989 and 1990. Three of the 4 patients healed successfully, another one died of multiple organ failure 83 days after surgery. All patients were received coronary artery bypass surgery harvesting a left internal thoracic artery for ischemic heart disease. Three patients had diabetes mellitus, one patient had renal failure preoperatively. Recognition of mediastinitis was made by sternal wound purulent discharge and sternal dehiscence. Culture of the discharge fluid yielded methicillin-resistant Staphylococcus aureus in three, and Enterococcus cloacae in one. Irrigation with popidone-iodine or blonopol were ineffective. Thus, the wound was treated with debridement and omentopexy with an omental pedicle flap, respectively. Postoperative course after omentopexy were excellent, had no complications. We conclude that the omentopexy is useful in the treatment of postoperative refractory anterior mediastinitis.

[A case of bilateral phrenic nerve paralysis following open heart surgery].

Coronary artery bypass surgery was performed on a 58-year-old female under cold cardioplegia with topical ice slush cooling. Bilateral phrenic paralysis was observed postoperatively, in spite of prevention with a mat during aortic cross clamp, cold injury owing to ice slush was thought to be causative. Mechanical ventilatory support continued for more than two months until her complete recovery of diaphragmatic function. She complained of sleeplessness besides respiratory symptoms, and felt uneasy. Although cold injury is mostly reversible, it is stressed that we must deliberately wean from mechanical ventilatory support, turning our attention to symptoms and blood gas analysis with as much mental assistance as possible.

[Two cases of postoperative erythroderma--clinical and pathological investigation].

Two cases of postoperative erythroderma, considered the Graft-Versus-Host disease like syndrome following blood transfusion during open heart surgery, were reported. In one, a 74-year-old female underwent the patch closure of ventricular septal perforation complicated with acute myocardial infarction, and in the other, a 67-year-old female underwent coronary artery bypass surgery. They had sudden fever, general eruption, liver dysfunction, leucopenia and thrombocytopenia, and died on the 15th and the 21st days after operation. In both, pathologically, eosinophilic necrosis was seen in agreement with basal cells and prickle cells on the epidermis. T-cells and monocytes widely infiltrated on the upper dermis, particularly around blood vessels. Furthermore, similar to on the skin, cellular infiltration and eosinophilic necrosis were seen on the esophageal mucosa. Various immunoglobulin-positive cells were seen on the dermis and the esophageal mucosa, but it is not clear that this is characteristic or not, because secondary infection possibly existed on them.

[Tighter tricuspid annuloplasty with DeVega technique for secondary tricuspid regurgitation].

More effective surgical treatment of secondary tricuspid regurgitation was investigated on the basis of intraoperative assessment of tricuspid regurgitation (TR) and clinicopathological study of right ventricular muscle biopsy. From March 1986 to February 1989, more aggressive narrowing of tricuspid valve ring using DeVega's method was performed on 29 patients. They were 8 men and 21 women, with the age of 28 to 71 (mean 53.5). Tricuspid annular diameter before procedure ranged from 31 to 45 mm in size, with the mean of 36.9 mm. Tricuspid annuli were constricted to 27 mm in 20 patients, and to 25 mm in 9 patients. Intraoperative evaluation of TR was done by digital examination from right atrium, contrast echocardiography, and filling regurgitation test on arrested or rebeating heart. But these intraoperative assessment of regurgitation did not predict postoperative residual tricuspid regurgitation. There was no early mortality. Postoperative residual tricuspid regurgitation was observed in only two patients (8.7%) of total cases within a follow-up period of 12 months. Quantitative study of extent of diffuse interstitial fibrosis of the right ventricular wall and diameter of right ventricular myocardial cells obtained by open transmural biopsy were done. The degree of diffuse interstitial fibrosis was assessed by the point-counting method, and mean percentage fibrosis (%fibrosis) was noted as 27.9%. Mean diameter of right ventricular myocardial cells was 19.5 microns in size. The diameter of right ventricular myocardial cell was correlated with pulmonary arterial pressure (r = 0.56).(ABSTRACT TRUNCATED AT 250 WORDS)

[Surgical results of high grade constriction of tricuspid annulus in DeVega technique for secondary tricuspid regurgitation].

Sixty-six patients were operated on by our high degree constriction technique using DeVega tricuspid annuloplasty from 1985 to 1989. They were 20 men and 46 women, age distributed from 28 to 71 (mean 54.5). Preoperative tricuspid annular diameter ranged from 29 mm to 45 mm, average 36.3 mm. Those were constricted to 27 mm in 38 patients, and to 25 mm in 28 patients. Postoperative residual tricuspid regurgitation was observed in only 8.5% of total cases followed up 14 to 55 months. This results were comparable with other reports. We concluded that our tight constriction DeVega method is considered better to prevent postoperative tricuspid regurgitation than ordinary methods.