[Thoracic aortic aneurysm due to giant cell arteritis without any specific symptom].

A 76-year-old female was admitted to our hospital for investigation and treatment of aortic regurgitation. She was found to have an ascending aortic aneurysm extending to the proximal arch. She had not suffered from any symptoms except chest discomfort. Total arch replacement and aortic valvoplasty were performed under cardiopulmonary bypass. Pathological examination of the aneurismal wall revealed giant cell arteritis. Aortic aneurysm due to giant cell aortitis without such symptom as temporal pain or polymyalgia was considered to be very rare.

[Gigantic coronary aneurysm arisen from coronary fistula between the left circumflex artery and the left ventricle].

A 71-year-old male was referred to our hospital due to abnormality detected by a chest roentgenogram. He had no symptoms except for slight chest oppression. He was found to have a giant coronary aneurysm. It was originated from a coronary artery (left circum flex branch) left ventricular fistula. The orifice of this fistula to the left ventricle was also dilated and formed diverticulum. Ligation of the feeding coronary branch, closure of the aneurysmal fistula in the left ventricular wall and aneurysmectomy were performed under cardiopulmonary bypass. Postoperative course was uneventful. A giant aneurysm originated from a coronary-left ventricular fistula was considered to be very rare.

[Questionnaire of cryopreserved allograft valves in Kyushu and Yamaguchi area].

Japanese Society of Cryopreserved Thoracic Tissue Implantation was recently set up. Cryopreserved allograft valves are about to pervade in Japan. To clarify the interest, demands and supply of cryopreserved allograft valve in the area of Kyushu and Yamaguchi, we performed questionnaire investigation regarding this issue. Collection rate of this questionnaire was 87.5% (35/40 hospitals). Ninety-seven percent of the hospitals answered that they were interested in cryopreserved allograft. Ninety-four percent of the hospitals answered that they did not ethically hesitate to use cryopreserved allograft. Ninety-one percent of the hospitals hoped to perform cardiac surgery using allograft aortic valve if allograft is available. With respect to securing donors of allograft, two-third of the hospitals did not decide whether they could be involved in obtaining donors of allograft. As the number of the cadaver kidney donors is about 20 per year in the area of Kyushu and Yamaguchi, shortage of donors of allograft valve is anticipated.

Postoperative cardiac rhythms with superior-septal approach and lateral approach to the mitral valve.

BACKGROUND: The superior-septal approach provides an excellent view of the mitral valve and therefore has received considerable interest. However, the safety of this approach is controversial because it requires division of the sinus node artery in most cases. METHODS: Postoperative cardiac rhythms were analyzed in 152 consecutive patients who underwent mitral valve procedures between January 1992 and February 1995 with a conventional right lateral left atriotomy (group 1, n = 69) or the superior-septal approach (group 2, n = 83). Follow-up ranged from 2 to 38 months, and the mean follow-up was 16.1 months in group 1 and 13.8 months in group 2. RESULTS: The mortality rate was similar in the two groups (1.4% in group 1 and 1.2% in group 2), and the causes of death were not related to the left atriotomy. At discharge, 96% of the patients in group 1 who were in sinus rhythm preoperatively and 78% of those in group 2 remained in sinus rhythm. At the last follow-up, 88% of these patients in group 1 and 83% in group 2 remained in sinus rhythm. Among the patients in atrial fibrillation or junctional rhythm before operation, 12% in group 1 and 11% in group 2 had regained sinus rhythm at the last follow-up. There were no significant differences in these values. CONCLUSIONS: Although the incidence of dysrhythmias was higher with the superior-septal approach in the early postoperative period, this approach provides an excellent operative view of the mitral valve and similar results in terms of late postoperative cardiac rhythms as the right lateral left atriotomy.

Preoperative autologous blood donations in pediatric cardiac surgery.

BACKGROUND: Preoperative autologous blood donation is one of the most effective methods to avoid homologous blood transfusion in cardiac operations. However, there have been few reports about the safety and efficacy of autologous blood donation in children. METHODS: Since 1986, we have instituted a blood conservation program including preoperative autologous blood donations in children. Eighty children as young as 3 years old (mean +/- SD, 8.6 +/- 3.9 years) and weighing as little as 12.3 kg (29.2 +/- 14.5 kg) were enrolled in the program, and 735 +/- 388 mL of blood was donated during an average of 3.1 +/- 1.5 phlebotomies before the operations. RESULTS: Two episodes of mild vasovagal reaction were observed in 2 patients as a complication of the phlebotomy. Seventy-six percent of the collected blood was stored by cryopreservation; the remaining 24% was preserved by liquid storage. Seventy-eight of these patients (97.5%) underwent operations using cardiopulmonary bypass. Seventy-five patients (94%) were operated on successfully without the need for a homologous blood transfusion. As for the other 5 patients, 2 received only platelet concentrate. CONCLUSION: Preoperative autologous blood donation is a safe and effective method to avoid homologous blood transfusion in pediatric cardiac operations.

The Cleveland Clinic-Nimbus total artificial heart. In vivo hemodynamic performance in calves and preclinical studies.

In vitro function of the Cleveland Clinic-Nimbus electrohydraulic total artificial heart met National Heart, Lung, and Blood Institute hemodynamic guidelines for such devices. In a series of in vivo experiments, we implanted the total artificial heart in eight calves (mean weight 87 kg), one for a short-term experiment and seven for long-term experiments. The mean blood flow during support was 7.7 +/- 1.6 L/min with left atrial pressure 13 +/- 6 mm Hg, right atrial pressure 13 +/- 4 mm Hg, and aortic pressure 97 +/- 9 mm hg. Maximum pump flow (9.6 L/min) occurred after 4 days of support as a result of the high resting cardiac output of the animals. A 10% to 15% right pump stroke-volume limit effectively balanced atrial pressures, and afterload insensitivity was confirmed by the in vivo studies. Calves tolerated treadmill exercise studies well, with an average duration of 22 minutes and an average top speed of 2.1 mph. The experiments were terminated after 1 day to 120 days of support (mean 32 days). Most experiments were terminated as a result of correctable mechanical problems. In a separate study of six adult human patients undergoing orthotopic cardiac transplantation, five showed an excellent fit for the Cleveland Clinic-Nimbus total artificial heart. Further studies using chest roentgenograms, chest measurements, and transesophageal echocardiography should help predict fit of the total artificial heart in potential candidates. Initial candidates for a "vented-electric" version of the Cleveland Clinic-Nimbus total artificial heart are patients for whom univentricular (left ventricular assist device) support is not appropriate, but who require mechanical support as a bridge to cardiac transplantation.

The effects of radiation therapy on the tissue capsule of soft tissue implants.

A prosthesis has been developed for cosmesis after lumpectomy surgery for breast carcinoma. The device is saline filled and percutaneously adjustable in volume to permit an optimal cosmetic result after surgical wound healing. A series of 24 studies of 18 weeks' duration using the adult rabbit animal model were first used to study tissue capsule formation around textured versus smooth surface control implants and to evaluate the effects of volume adjustments on the tissue capsule. Single or multiple adjustments of implant volume had no effect on tissue capsule thickness or morphology. Because lumpectomy surgery is invariably followed by radiation therapy, a series of six studies was then conducted to determine the effects of a typical course of radiation therapy on tissue capsule formation. One week after device implantation, a 4 x 4 cm field including the implant was irradiated with 5,000 rad (200 rad/day x 5 days/week x 5 weeks). The animals were maintained for a 6 week period after radiation treatment. After sacrifice, the implants were removed, and the tissue capsules studied using conventional histologic techniques, including scanning and transmission electron microscopy. There was no statistically significant difference in tissue capsule thickness compared to nonirradiated controls. Tissue capsule morphology, however, differed markedly. Radiation therapy decreased angiogenesis, cellularity, and the inflammatory cell response to the implants. Qualitatively, radiation treatment seemingly improved rather than compromised the connective tissue response to the implants.

Progress in Cleveland Clinic-Nimbus total artificial heart development.

A totally implantable, Cleveland Clinic-Nimbus total artificial heart (TAH) uses electrohydraulic energy conversion and an automatic left master-alternate mode control scheme, with a filling sensitivity of 1.0 l/min/mmHg and a maximum output of 9.5 l/min. The TAHs were tested in 12 calves for 1-120 days with normal major organ and blood cell function. Post-operative suppression of platelet aggregation recovered by the second post-operative week. The gelatin-coated pump surface generally was clean without any anticoagulants and free from infection. Embolism, which occurred in two cases, was caused by complications attributable to fungal infection in a Dacron graft and by thrombus formed around a jugular vein catheter. A system with a hybridized microcircuit controller in the interventricular space has been tested successfully in the three most recent cases, with a peak device surface temperature elevation of 6.5 degrees C. Heat effects were confined to the tissues immediately adjacent to the hottest spots. The carbon fiber-reinforced epoxy housing and 60 ml butyl rubber compliance chamber showed good tissue compatibility with a thin, fibrous tissue capsule. The transcutaneous energy transmission system and the internal battery functioned well as designed in the most recent animal implant.

Adaptation of tissue to a chronic heat load.

Determination of the chronic effect of heat on tissue is one of the important issues facing mechanically actuated total artificial heart (TAH) development. In an effort to characterize this effect, implantations of heating devices producing constant heat fluxes of 0.04 watts/cm2, 0.06 W/cm2, and 0.08 W/cm2 were performed in 11 calves (H-series). Heated disks were implanted adjacent to lung and muscle tissue for a period of 7 weeks. Temperature sensors were placed at the surface as part of the heater assemblies. The results showed that initially, temperature elevations above body temperature (delta T) were 6.4 +/- 0.6 degrees C, 4.5 +/- 0.2 degrees C, and 1.8 +/- 0.5 degrees C at the muscle heater surface for 0.08, 0.06, and 0.04 W/cm2, respectively. At 2 weeks after implant delta T values changed to 5.5 +/- 0.6 degrees C, 3.4 +/- 0.2 degrees C, and 1.8 +/- 0.2 degrees C, respectively. Seven weeks after implant, delta T values decreased to 3.7 +/- 1.2 degrees C, 2.8 +/- 0.1 degrees C, and 0.8 degrees C for 0.08, 0.06, and 0.04 W/cm2, respectively. The authors think this change is attributable to an adaptive response of the tissue to increase heat dissipation through angiogenesis. Results from three TAH cases indicated that at two measured tissue interfaces, delta T decreased by 1 degrees C during a 15 day period. At the same time, the waste heat (volts x current in-flow x afterload to the blood) remained constant at 11.1 +/- 0.5 W during this period. This decrease in delta T corresponded to that observed for the H-series experiments at the higher heat fluxes. Thus, it appears that adaptation observed in the H-series experiments also is seen for tissues surrounding heat sources such as the TAH.

Tranexamic acid reduces blood loss after cardiopulmonary bypass.

To evaluate the effect of tranexamic acid (TA) on blood loss after cardiopulmonary bypass (CPB), 157 patients who underwent elective valve replacement operations were studied, with one group of 90 patients receiving tranexamic acid (Group TA) and 67 patients serving as the control group (Group N). In group TA, 50 mg/kg of tranexamic acid was administered just before and after CPB, and every 90 minutes during CPB. The activated coagulation time was maintained at more than 450 seconds during CPB in both groups. There was no significant difference in the CPB time between the groups (163 +/- 32 min in group N and 152 +/- 38 min in group TA:NS). The time required for hemostasis was shortened in group TA, which resulted in a shorter operation time (6.7 +/- 1.5 hrs vs 6.0 +/- 1.5 hrs in group N and group TA, respectively: p = 0.006). The amount of chest tube drainage within 12 hours after surgery was significantly reduced (225 +/- 129 ml vs. 180 +/- 118 ml in group N and group TA, respectively: p = 0.026). The chest tube was able to be removed earlier in group TA, and the total blood loss was significantly smaller in group TA (402 +/- 292 ml) than in group N (631 +/- 609 ml; p = 0.004). The authors thus conclude that antifibrinolytic therapy during CPB with tranexamic acid reduces postoperative blood loss, and shortens the operation time due to an improvement in hemostasis.

Development of a magnetically operated artificial urethral sphincter. Chronic effects of compression on the skin structure and blood flow.

The artificial urethral sphincter (AUS) has been in clinical use for more than 20 years. Currently available AUS devices, however, are difficult to use and not entirely reliable. A magnetically operated AUS is currently under the development. Although the skin between the magnets will be compressed all day long, little information exists on the effects of chronic pressure on the skin structure and blood flow. In five miniature pigs, two internal magnets and one control metal disk were implanted subcutaneously at three different positions, and external magnets with differing magnetic forces were applied to the skin overlying the internal magnets for six weeks. In four pigs, the skin blood flow was measured by a laser Doppler flow meter applying different pressures. Compression of 10 mmHg preserved normal skin morphology in all but one animal where blood flow had not recovered 2 weeks after surgery. Compression of 20 mmHg for 6 weeks, however, produced pressure ulcers in all five cases (p < 0.05 vs. 10 mmHg group). The skin blood flow declined for pressures exceeding 20 mmHg (0 mmHg: 4.3 +/- 1.2, 10 mmHg: 4.3 +/- 3.3, 20 mmHg: 2.6 +/- 2.7 ml/min/100 g). We concluded that the magnetically operated AUS should use a magnetic coupling with a pressure less than 10 mmHg exerted on the interposing skin.

Hemodynamic changes with posture in calves with total artificial heart.

Hemodynamic changes with posture, sitting versus standing, were analyzed in five Holstein calves with the Cleveland Clinic-Nimbus TAH. This total artificial heart (TAH) has a left master alternate control mode that adjusts the pump rate and consequently pump flow proportional to the pulmonary venous return to the left pump (AUTO period). However, in this series of experiments, the pump reached its maximum beat rate within 1-5 days post operatively, after which pump flow could not increase (MAX period). Hemodynamic parameters (RAP, LAP, PAP, AoP, and pump flow) were obtained every 15-20 min throughout the experiments for as long as 120 days and averaged for each posture for each period. During the AUTO period, the flow while standing was significantly higher than that while sitting (standing: 8.7 +/- 0.2 L/min; sitting: 7.5 +/- 0.4 L/min; p < 0.05), and the systemic vascular resistance (SVR) was significantly lower (standing: 895 +/- 93 dyne.sec.m-5; sitting: 1,041 +/- 124 dyne.sec.m-5; p < 0.05). During the MAX period, the AoP and SVR standing were significantly lower than those sitting (AoP standing: 91 +/- 7 mmHg; AoP sitting: 98 +/- 7 mmHg; p < 0.05; SVR standing: 652 +/- 75 mmHg; SVR sitting: 730 +/- 96 mmHg; p < 0.05). The Cleveland Clinic-Nimbus TAH responded well to these changes in position, increasing pump flow and maintaining the AoP during the AUTO period.

Effects of a total artificial heart right stroke volume limiter on left-right hemodynamic balance.

In a completely implantable total artificial heart (TAH), the left-right flow difference attributable to higher volumetric efficiency of the right pump and bronchial artery shunting has always been a significant problem. The automatic control of the Cleveland Clinic-Nimbus TAH accommodates for the left-right flow difference when the beat rate is below maximum (AUTO range). However, at its maximum beat rate (MAX), high left atrial pressure (LAP) (greater than 25 mmHg) with relatively low right atrial pressure (RAP) (less than 8 mmHg) were observed both in vitro and in vivo, suggesting the need for a stroke volume limiter (SVL) of the right pump. In vitro volume loading tests showed 10%, 15%, and 20% SVLs prevented a disproportionate increase of LAP. In vivo studies in five Holstein calves also showed a balanced LAP-RAP relationship with 10% and 15% SVLs at MAX. The left pump flow was not affected by this range of SVLs either in vitro or in vivo. Pulmonary function was maintained with either size SVL, with autopsies revealing absence of pulmonary congestion and minimal pleural effusions in two calves surviving for more than 1 month. Although additional studies are needed to determine the appropriate size of the SVL, both 10% and 15% SVLs were effective in maintaining left-right hemodynamic balance in this TAH.

A new finger joint prosthesis.

A new finger joint prosthesis is being developed for the proximal and distal interphalangeal positions. Currently available "joint spacer" prostheses provide relief from pain and cosmetic improvement, but relatively poor long-term function. The new prosthesis employs a mechanical hinge at the joint. It is fabricated from titanium alloy (6A14V). The hinge mechanism avoids direct metal to metal contact by using high density polyethylene bearings. In vitro tests of the hinge mechanism have passed 75 million cycles of continuous flexure without failure (n = 12). The hinge also incorporates a mechanical limit stop to prevent hyperextension. The hinge mechanism is enclosed in a sealed elastomeric jacket that isolates the hinge from connective tissue ingrowth. The jacket, equivalent to an artificial synovial membrane, has an integrally textured exterior surface designed to promote tissue attachment to the implant to stabilize tissue capsule formation around the joint. To test the in vivo efficacy of the new design, a series of 12 devices were implanted in the knee joint position of adult rabbits. A jacketed prosthesis was implanted on one side, whereas 2 weeks later an unjacketed control was implanted contralaterally. The animals then were maintained for an 8 week period. At sacrifice, the implants were removed, and the response of the surrounding tissues was studied histologically. At the time of implantation, the range of motion of the joints was approximately 100-105 degrees. There was a progressive loss in range of motion observed in both groups. The fibrous tissue capsule around the jacketed implants, however, was significantly reduced in thickness compared with the controls (mean thickness, 1.5 mm vs. 4.5 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pump flow rate on oxygen use during moderate hypothermic cardiopulmonary bypass.

The authors investigated the effects of pump flow rate on oxygen use during a moderate hypothermic cardiopulmonary bypass (CPB) in 31 patients during either coronary artery bypass grafting or valve replacement and aortic cross clamping. Intravenous anesthesia was performed with high dose fentanyl. A neuromuscular blockade was achieved with an intravenous infusion of pancuronium. After a stable rectal temperature of 29 degrees C was obtained by both surface cooling with a blanket and core cooling with CPB, the pump flow rate was changed from 2.4 L/min/m2 to 2.2, 2.0, 1.8 and 1.6, keeping the same flow rate for at least 5 min. Both arterial and venous blood was sampled for blood gas analysis; serum lactate measurement and hemodynamic changes were monitored and recorded at each flow rate. In 10 of 31 patients, whose aortic cross clamping time was longer than 90 min, the same measurements were followed 10 min after the induction of prostaglandin E1 (PGE1) (40 +/- 13 ng/kg/min) at pump flow rates of 2.4, 2.0, and 1.6 L/min/m2. Oxygen consumption significantly decreased at 1.6 L/min/m2 compared to the other flow rates (52.4 +/- 13.6, 54.3 +/- 11.8, 56.4 +/- 14.7, and 56.7 +/- 11.0 ml/min/m2, at flow rates of 2.4, 2.2, 2.0 and 1.8 L/min/m2, respectively, versus 48.4 +/- 10.9 ml/min/m2, at 1.6 L/min/m2, p < 0.01, paired t-test). After the induction of PGE1, both aortic pressure and systemic vascular resistance decreased significantly (p < 0.01, paired t-test) at flow rates of 2.0 and 1.6 L/min/m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of diltiazem and noradrenaline on extracellular potassium changes in the globally ischaemic rat heart.

OBJECTIVE: The aim was to investigate the effects of a calcium antagonist (diltiazem) and a catecholamine (noradrenaline) on extracellular potassium accumulation during global ischaemia. METHODS: Extracellular potassium concentration ([K+]e) was measured during 30 min global ischaemia in the isolated rat heart using a valinomycin potassium sensitive electrode. Contracture development during ischaemia was measured throughout with an intraventricular balloon inserted into the left ventricle and myocardial adenine nucleotides were measured in separate series of hearts. RESULTS: In control hearts, [K+]e showed a characteristic triphasic change during 30 min global ischaemia. This consisted of an early rising phase followed by a transient falling phase after the initial peak of [K+]e, and then a late rising phase. Diltiazem suppressed the rate of rise of [K+]e during early ischaemia, but extended the time course of the early [K+]e rise with the higher dose, abolishing the transient falling phase of [K+]e. During late ischaemia, the rise in [K+]e was attenuated by diltiazem. Noradrenaline also suppressed the early extracellular potassium accumulation, but in contrast to diltiazem, hastened the time course of the late [K+]e rise. CONCLUSIONS: Although diltiazem suppresses the early potassium loss during ischaemia as previously described, the drug also decreases the [K+]e fall by some as yet unknown mechanism, so that the [K+]e level becomes higher than control during the falling phase.

Effects of glibenclamide and nicorandil on cardiac function during ischemia and reperfusion in isolated perfused rat hearts.

We examined influences of a blocker (glibenclamide) and an opener (nicorandil) of the ATP-sensitive potassium (KATP) channel on extracellular K concentration [( K+]e), as well as the myocardial function and metabolites during global ischemia and reperfusion in Langendorff-perfused rat heart preparation. In control hearts, [K+]e began to rise 20 s after the onset of ischemia up to an initial peak (8.3 +/- 0.3 mM) at 2.5 +/- 0.7 min, then fell to 6.0 +/- 0.8 mM after 8.2 +/- 0.7 min, and then rose progressively to 14.6 +/- 0.8 mM at the end of 30 min of ischemia. Glibenclamide (50 microM) reduced the initial peak of [K+]e to 7.2 +/- 0.3 mM (P less than 0.01), and nicorandil (200 microM) increased it to 9.4 +/- 0.6 mM (P less than 0.01). There were no significant differences in [K+]e values among all groups at the end of ischemia. During ischemia, nicorandil decreased the time to mechanical arrest from 1.9 +/- 0.1 min to 1.5 +/- 0.1 min, whereas it was increased by glibenclamide to 2.7 +/- 0.4 min. In control hearts, the time to onset of ischemic contracture was 14.7 +/- 1.8 min. Nicorandil delayed onset of contracture and glibenclamide accelerated it. Thus we have confirmed that some part of the early increase in [K+]e during ischemia is attributable to K+ efflux through the KATP channel in our model, and opening of the KATP channel may contribute to a rapid reduction of the contractility of the ischemic myocardium that subsequently protects the myocardium against further ischemic injury.

[Retrograde coronary sinus perfusion of cardioplegic solution in Jatene operation in neonates and infants].

The clinical benefits of retrograde coronary sinus perfusion of a cardioplegic solution were investigated in 7 neonates and 23 infants undergoing Jatene operation. After an initial infusion of albumin-containing crystalloid cardioplegic solution via the aortic root, 21 patients received additional solution delivered by retrograde coronary sinus perfusion (retrograde group) and 9 patients received by selective antegrade coronary perfusion (antegrade group) every 20 to 30 minutes. There were no differences in age, weight, and left ventricular preoperative pressure and morphology between the two groups. Aortic cross-clamping time was 130 +/- 18 minutes in retrograde group and 147 +/- 20 minutes in antegrade group. Postoperative assays of CPK-MB, GOT and LDH, and hemodynamic measurements immediately after cessation of cardiopulmonary bypass (CPB) were carried out in all patients. Although there was no significant difference between the two groups in terms of enzyme indexes, retrograde group showed a greater variation of sigma CPK-MB from patient to patient than antegrade group. However, hemodynamic parameters of CVP, left atrial pressure and rate-pressure product at 20-30 minutes after CPB were similar in the two groups. Six neonates in retrograde group also demonstrated the similar enzyme indexes and hemodynamic state immediately after CPB to other older patients. We concluded, therefore, that retroperfusion of cardioplegic solution in neonates and infants provides satisfactory myocardial protection as well as antegrade perfusion, and it was a useful means of cardioplegic delivery in Jatene operation, because of its simplicity.