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The present study was performed to determine whether the effects of ischemic preconditioning are mediated by a decrease in myocardial contractile activity or by a change in catabolite accumulation during the subsequent period of sustained ischemia. In ischemic preconditioning groups, crystalloid perfused rat hearts were subjected to 5 or 10 min of global ischemia before a 15-min reperfusion period and a subsequent 30 min period of ischemia, Non-preconditioned control hearts underwent a single 30-min ischemic period. In the 5-min preconditioned hearts, the onset of myocardial contracture was significantly delayed (22.0 +/- 1.6 min) compared with that in control hearts (14.7 +/- 0.7 min). Tissue ATP content of the myocardium during sustained ischemia was preserved better in 5-min preconditioned hearts than in control hearts. The time to contractile arrest during the sustained ischemic period was greater in the preconditioned hearts (3.9 +/- 0.3 and 3.1 +/- 0.2 min in PC5 and PC10 hearts respectively) than in controls (1.9 +/- 0.1 min). Thus, residual myocardial work during sustained ischemia (as estimated by the rate pressure product) was not decreased in the preconditioned hearts compared with that in control hearts. Extracellular acidosis was identical among the three groups during the subsequent period of sustained ischemia. The early rise in extracellular K+ during sustained ischemia progressively increased with the duration of preconditioning. We conclude that, in crystalloid perfused rat heart, 5 min of global ischemia had a salutary effect against cell damage caused by sustained ischemia. This "preconditioning" effect cannot be attributed to decreased myocardial work during ischemia nor to differences in extracellular H+ or K+ accumulation.

The mitral apparatus can affect left ventricular function through various mechanisms, such as the direct mechanical coupling between the mitral anulus and papillary muscle and the mitral annular contraction. To evaluate the relative contribution of these mechanisms, we investigated in five groups of 35 dogs that underwent open chest operations how preservation of the mitral apparatus affects left ventricular systolic function. We performed atriotomy in the first group. We sutured a prosthetic rigid ring around the mitral anulus in the second group. We replaced the mitral valve and preserved the anterior chordae in the third group, the posterior chordae in the fourth group, and no chordae in the fifth group. The postoperative percentage of recovery of ventricular function (as assessed by the slope of the end-systolic pressure-volume relation) from preoperative control values were 92.2% +/- 4.8%, 89.5% +/- 12.8%, 85.7% +/- 9.5%, 75.1% +/- 12.9%, and 61.3% +/- 8.0%, respectively. Preservation of the mitral apparatus significantly improved left ventricular function compared with that of conventional mitral valve replacement. The average relative contribution of the ventricular muscle to left ventricular function, the mitral anulus-papillary muscle continuity, and the mitral annular contraction were 66.5%, 30.6%, and 2.9%, respectively. We conclude that it is more beneficial to preserve the mitral apparatus in mitral valve replacement. The prosthetic ring does not detract from the functional benefit of the preservation of the mitral apparatus.

From February 1975 to August 1981, 23 consecutive patients underwent tricuspid valve replacement, which was either isolated (six patients) or combined with the replacement of other valves (17) by means of a standard, glutaraldehyde-preserved Hancock porcine bioprostheses. Patients’ ages ranged from 9 to 53 (mean 36.2) years. The follow-up period ranged from 0.2 to 16.5 years (mean 9.1) and was complete in 100 % of all cases. Structural valve failure of the tricuspid Hancock valve was noticed in two patients, a 9-year-old boy and a 13-year-old girl 3.4 and 16.5 years after implantation, respectively. The actuarial freedom rate from structural valve failure at 10 years was 94 ± 6 %. There were six tricuspid prosthesis-related events: structural valve failure in two and valve thrombosis, anticoagulant-related bleeding, prosthetic valve endocarditis, and periprosthetic leak in one each, respectively. The actuarial freedom from these events at 10 years was 78 ± 10%. Five pairs of aortic/mitral-tricuspid Hancock valves were explanted simultaneously from the same patients after 8.1 to 13.9 (mean 11.4) years postoperatively. A gross examination showed no valve dysfunction in the explants from the tricuspid position, but degenerative changes with valve dysfunction in those from the mitral and aortic position were observed (none of five versus five of seven; p

The following hypotheses were tested using an isolated perfused working rat heart model: (1) Collins' solution for cold storage of the heart is harmful for the heart during reperfusion; (2) a "reverse" of the intracellular-type Collins' solution with an extracellular-type cardioplegic solution before reperfusion is able to prevent this disadvantage of Collins' solution. The following two major groups (I and II) and five subgroups (-a to -e) in each group were prepared. In group I (reversed group); the hearts were initially stored in Collins' solution but were reversed by a 1-minute flush with cardioplegic solution followed by storage in cardioplegic solution for the last 1 to 180 minutes of the total 3-hour storage, that is, groups I-a (reversed for 1 minute), I-b (10 minutes), I-c (30 minutes), I-d (90 minutes), and I-e (180 minutes). In group II (nonreversed control group); the hearts were stored in Collins' solution throughout 3 hours and were also divided into five subgroups of groups II-a, II-b, II-c, II-d, and II-e in which only a 1-minute flush with Collins' solution was performed at the point corresponding to group I. The coronary flow in any of group II showed a marked decrease during the early reperfusion period. In group I, however, the coronary flow increased significantly in proportion to the duration of the reversing phase. The recovery of the aortic flow and the cardiac output in group I showed a bell-shaped pattern in relation to the duration of the reversing phase, reaching their peak values when reversed for 30 minutes (group I-c). The prolonged reverse (180 minutes) resulted in a deterioration of functional recovery associated with a poorer preservation of high-energy phosphates and a larger enzyme leakage. These results suggest that the beneficial effects of intracellular-type Collins' solution for cold storage of the heart were further improved by reversing Collins' solution with the extracellular-type cardioplegic solution for the last 30 minutes of the 3-hour cold storage because the disadvantageous vasoconstriction due to Collins' solution during reperfusion was successfully prevented by the replacement of intravascular and extravascular Collins' solution with cardioplegic solution before the reperfusion.

Mechanisms and kinetics of the effects of the ionic composition of two different storage solutions, an intracellular type and an extracellular type, were analyzed by examining the myocardial functional and metabolic recovery processes during the early reperfusion periods after 3 hours of cold storage using an isolated perfused working rat heart model. The hearts were stored either in our own cardioplegic solution (group 1) or in Collins’ solution (group 2) for 3 hours at 4° C and were then reperfused. The electromechanical activity in group 1 was elevated, as indicated by a higher incidence of ventricular fibrillation at 5 minutes of reperfusion (group 1: 5/6; group 2: 0/5; p horac C ardiovasc S urg 1992;104:1320-8)

To assess the underlying mechanisms of ventricular fibrillation induced by myocardial reperfusion after cardioplegic arrest, 62 patients undergoing an open heart operation were divided into two groups based on the absence (group 1, n = 37) or the development (group 2, n = 25) of reperfusion-induced ventricular fibrillation. There was no close relationship between the incidence of reperfusion-induced ventricular fibrillation and aortic clamp time. On reperfusion, the time to onset of cardiac activity was similar in groups 1 (2.4 +/- 1.8 minutes) and 2 (1.9 +/- 1.1 minutes). At that time, there was no significant difference in values of arterial oxygen and bicarbonate contents, pH, or base excess between the two groups, but myocardial temperature was significantly higher in group 2 (25.6 degrees +/- 3.4 degrees versus 27.6 degrees +/- 2.4 degrees C; p less than 0.05). In addition, serum levels of sodium (123.9 +/- 4.2 versus 126.1 +/- 3.7 mmol/L; p less than 0.05) and calcium (0.80 +/- 0.07 versus 0.84 +/- 0.05 mmol/L; p less than 0.05) were significantly higher and serum potassium levels (3.98 +/- 0.58 versus 3.55 +/- 0.61 mmol/L; p less than 0.02) and the serum potassium to calcium ratio (4.94 +/- 0.90 versus 4.29 +/- 0.72; p less than 0.01) significantly lower in group 2. Postoperative serum levels of the myocardial-specific isoenzyme of creatine kinase and myoglobin were similar in both groups. By multivariate analysis, shorter ischemic time, higher myocardial temperature, higher serum sodium concentration, and lower serum potassium to calcium ratio were found to influence induction of reperfusion-induced ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

大動脈弁と僧帽弁の二弁置換症例を対象に, 心筋保護液の順行性投与 (Ante) 法と逆行性投与 (Retro) 法の心筋保護効果を比較した. Ante 群15例, Retro 群 (Ante 法併用 Retro 法) 13例について, 術前および術中因子, 再灌流後CPK-MB値の推移, 術周期心筋梗塞の頻度, 術後血行動態を検討した. 術前因子は両群間に差を認めなかった. 大動脈遮断中の心筋保護液投与の間隔は Ante 群29.2±4.8分, Retro 群24.0±3.8分と Retro 群にて有意に (p

Continuous intravenous infusion of chlorpromazine (CPZ) was used for both sedation and after-load reduction in 13 Japanese patients (Group 1) supported by an intraaortic balloon pump (IABP) after open-heart surgery. CPZ was initiated at a dose of 0.05 mg/kg/hr and was maintained in an approximate dose range of 0.1-0.3 mg/kg/hr depending on individual patient needs. The drug was administered until the IABP was removed and the blood gases were normalized. During this period, the patients slept well and the trigger lines for the IABP were sufficiently secured. In order to evaluate the hemodynamic changes in these patients, the 10 patients who were supported by the IABP and given continuous intravenous sodium thiamylal (ST) for sedation in an approximate dose range of 1-2 mg/kg/hr (Group 2) were employed as controls. After administration of CPZ, the systemic vascular resistance, central venous pressure, and left atrial pressure decreased, while the cardiac output increased. The predicted untoward effects of CPZ, such as tachycardia and hypotension, were minimal. In the ST group, by contrast, the cardiac output decreased somewhat in association with the increase in systemic vascular resistance. From these results, we conclude that constant intravenous CPZ is beneficial for postcardiotomy patients who have severe low cardiac output syndrome and are supported with IABP, by both successfully sedating the patients and reducing ventricular afterload.

Left ventricular hypertrophy has been reported after ascending aorta-abdominal aorta bypass, despite seemingly insignificant changes in cardiac output and mean arterial pressure. Such a bypass procedure may be used for the treatment of complex coarctation of the aorta, hypoplastic aortic arch, or thoracoabdominal aortic aneurysm. To investigate the effect of the bypass procedure on left ventricular afterload, we measured aortic input impedance in six open chest dogs by placing a knitted Dacron graft from the ascending aorta to the abdominal aorta and occluding the aortic arch. Cardiac output and mean arterial pressure remained unaltered throughout the experiment, consistent with clinical reports. Systolic pressure increased by 25% of control, and the ratio of diastolic pressure-time index to tension-time index decreased by 27%. The measured input impedance was then approximated with the three-element windkessel model, which consists of resistance, compliance, and characteristic impedance (average of impedance modulus between 5 and 15 Hz). There was no change in resistance and compliance; characteristic impedance increased to 255% of control. Connecting an air chamber to the vascular prosthesis doubled the compliance and decreased the characteristic impedance nearly to the control value without altering resistance. It also reduced the systolic pressure by 14% of the bypass protocol and increased the ratio of diastolic pressure-time index to tension-time index (by 32% of control value and 82% of bypass value). Arterial systolic pressure and pulse pressure were both linearly correlated with the characteristic impedance. Thus we conclude that although ascending aorta–abdominal aorta bypass does not affect cardiac output, mean arterial pressure, resistance, or compliance, it does increase characteristic impedance. Left ventricular systolic load is directly correlated with characteristic impedance. Increased systolic wall stress might be the cause of left ventricular hypertrophy of the previously reported cases. Because decrease in the distensibility of the proximal aorta is one of the factors causing the increase in characteristic impedance, using a compliant graft might help to unload the heart.

The protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium has been assessed in adult patients undergoing heart operations. Postreperfusion recovery of cardiac function and electrical activity was evaluated in 34 patients; 16 received low-calcium, magnesium-free potassium cardioplegic solution (group I) and 18 received St. Thomas’ Hospital solution, which is enriched with calcium and magnesium (group II). There were no significant differences between the two groups in age, sex, body weight, and New York Heart Association functional class. Aortic occlusion time (107.3 ± 46.8 minutes versus 113.6 ± 44.3 minutes), highest myocardial temperature during elective global ishemia (11.5° C ± 3.1° C versus 9.3° C ± 3.2° C), and total volume of cardioplegic solution (44.2 ± 20.5 ml/kg versus 43.4 ± 17.6 ml/kg) were also similar in the two groups. On reperfusion, electrical defibrillation was required in four cases (25.5%) in group I and in 15 cases (83.3%) in group II (p

To evaluate the effects of pericardial meshing (multiple incisions on the pericardium) on cardiac function, we examined left ventricular pump performance before and after pericardial meshing in six open chest dogs. We evaluated left ventricular systolic properties with the slope of end-systolic pressure-volume relation and diastolic properties with end-diastolic pressure-volume relation (chamber compliance). Overall left ventricular performance was assessed with end-diastolic pressure versus cardiac output relation. Left ventricular chamber compliance was increased (31.3%) with pericardial meshing compared with direct closure of the pericardium, and cardiac output was increased (26.7%) for any given left ventricular end-diastolic pressure. The slope of the end-systolic pressure-volume relation was not altered in pericardial meshing. These results suggest that pericardial meshing improves left ventricular pump performance as a result of increasing left ventricular chamber compliance. This technique may benefit cardiac pump performance that is depressed by the direct closure of the pericardium after cardiac operations.

We report a case of a 40-year-old man who had a quadricuspid aortic valve associated with aortic regurgitation. The anomaly was revealed by transesophageal echocardiography (TEE), and confirmed by cardiac surgery. TEE is a useful noninvasive method for identifying the quadricuspid aortic valve.

Hemoconcentration for the establishment of no-donor blood transfusion in open heart surgery was assessed in regard to both the saving of protein and platelets and the exclusion of free hemoglobin. Two different types of hemoconcentrator were compared: the ultrafilter (group I, 6 patients) and the Cell Saver (group II, 6 patients). The total serum protein level, expressed as the percent recovery of the preoperative value, after hemoconcentration was significantly higher in group I (group I versus group II: total serum protein, 118% versus 87% [p less than 0.05]; fibrinogen, 77% versus 50% [p less than 0.01]; immunoglobulin, 83% versus 60% [p less than 0.01]). The platelets also seemed to be well preserved after hemoconcentration in group I. Although the exclusion of free hemoglobin from plasma was inferior in group I compared with group II, the postoperative plasma free hemoglobin level did not increase in group I. We conclude that use of the Cell Saver in nontransfusion cardiopulmonary bypass might cause a severe depletion of various proteins and that the ultrafilter is both safer and more useful if employed routinely.

Although left heart bypass has gained popularity as a powerful technique to assist the severely failed left heart, apparent right heart failure has often developed during the bypass procedure. We investigated whether the coexisting right heart failure is attributable to the left heart bypass in 16 open-chest dogs. We evaluated the effects of left heart bypass on the right ventricular systolic properties by the slope of the end-systolic pressure-volume relation and its effects on the diastolic properties by chamber compliance. Overall right ventricular performance was assessed by the end-diastolic pressure versus cardiac output relationship. The left heart bypass decreased the slope slightly when the assisted flow ratio exceeded 75% (‘-14% ±8% at the assisted flow ratio of 100%, p

Retrograde administration of cardioplegic solution via the right atrium with continuous cooling of the right ventricular cavity (right atrial perfusion cooling) was assessed for its protective effect in 12 dogs with occlusion of the right coronary artery subjected to global ischemia for 60 minutes. After an initial administration of 4° C crystalloid cardioplegic solution by antegrade aortic perfusion, myocardial protection was established either by right atrial perfusion cooling (group I; n = 6) or by antegrade aortic perfusion alone (group II; n = 6). The right ventricular temperature was approximately 15° C in group I and 20° C in group II. After ischemia for 60 minutes, the adenosine triphosphate content of the right ventricular free wall was significantly higher in group I than in group II (24.4 ± 1.45 versus 13.8 ± 234 μmol/gm dry weight, p

Comparative long-term performance characteristics of mechanical valves and bioprosthetic valves were analyzed retrospectively for patients who had undergone isolated mitral valve replacement from 1967 to 1988. Two hundred ninety-one patients received either mechanical (n = 97) or bioprosthetic (n = 194) valves. The cumulative follow-up was 1,609 patient-years (mean 6.3 +/- 3.8 years, ranging from 0.6 to 20.2 years, 98.9% complete follow-up). The actuarial survival rate, including hospital deaths, at 10 years was 72 +/- 12% for mechanical and 74 +/- 4% for bioprosthetic valve recipients. The rates of freedom from thromboembolism, structural valve failure, prosthetic valve endocarditis, prosthetic valve endocarditis, reoperation, and overall valve-related complications at 10 years were 87 +/- 5%, 100%, 91 +/- 3%, 100%, and 79 +/- 8% for mechanical valve recipients and 85 +/- 3%, 77 +/- 5% (p less than 0.001), 85 +/- 13%, 71 +/- 5% (p less than 0.001), and 52 +/- 5% (p less than 0.001) for bioprosthetic valve recipients, respectively. Thromboembolism occurred at a similar incidence in two types of valves (2.0 +/- 0.7 vs. 2.2 +/- 0.4%/pt-yr). Structural valve failure, reoperations, and overall valve-related events occurred more frequently in the bioprostheses recipients (0 vs. 2.0 +/- 0.4%/pt-yr; p less than 0.001, 0.3 +/- 0.3 vs. 2.9 +/- 0.5%/pt-yr; p less than 0.001, 2.5 +/- 0.8 vs. 5.6 +/- 0.7%/pt-yr; p less than 0.005, respectively). There was no mortality at the time of redo-operation. These results show that bioprostheses in the mitral position exhibit small benefits of antithrombogenesis and prominent disadvantage of poor durability requiring reoperation.

Comparative long-term performance characteristics of mechanical valves and bioprosthetic valves were analyzed retrospectively among patients who had undergone isolated aortic valve replacement between 1968 and 1987. One hundred sixty-seven patients received either mechanical (n = 82) or bioprosthetic (n = 85) valves. The cumulative follow-up was 926 patient-years (mean 6.1 +/- 4.7 years, ranging from 0.5 to 20.2 years, 100% complete follow-up). Actuarial survival rate, including operative death, at 10 years was 74 +/- 7% for mechanical and 77 +/- 7% for bioprosthetic valve recipients. The rates of freedom from thromboembolism, structural valve failure, prosthetic valve endocarditis, and valve re-replacement at 10 years were 77 +/- 7%, 100%, 96 +/- 2% and 95 +/- 3% for mechanical, and 94 +/- 4%, 83 +/- 8% (p less than 0.05), 88 +/- 5% and 75 +/- 8% (p less than 0.05) for bioprosthetic valve recipients, respectively. Thromboembolism occurred more frequently in the mechanical valve recipients (p less than 0.01), and structural valve failure in the bioprostheses recipients (p less than 0.05). There was no mortality at the time of valve re-replacement. Most of the bioprosthesis recipients received no anticoagulation therapy beyond 3 months postoperatively. Cardiac medication in the late postoperative period was not required in 31.3% of bioprosthetic, and 3.2% of mechanical valve recipients (p less than 0.01). These results show that bioprosthesis in the aortic position exhibits a superb antithrombogenicity and may enable a drug-free state, though its limited durability requires reoperation.

Protamine sulfate often causes hypotension during heparin neutralization. The concept of ventricular-arterial coupling was applied to determine whether a negative inotropic effect or a vasodilating effect of protamine was the major contributing factor to this hypotension. Thirty-five patients who underwent cardiac operations were studied during operation by measuring instantaneous left ventricular pressure and aortic flow to examine the end-systolic pressure-volume relationship. We obtained end-systolic elastance and effective arterial elastance values in a beat-to-beat fashion with a single-beat estimation method. In 28 of the 35 patients (80%), mean arterial pressure decreased more than 10 mm Hg with protamine infusion. Parameters were compared at the following three points: before a decrease in mean arterial pressure (control), at maximally decreased mean arterial pressure (maximum), and at a middle point between control and maximum values (midpoint). At both midpoint and maximum, mean arterial pressure decreased significantly (control 79.6 ± 12.6 mm Hg, midpoint 66.5 ± 10.8 mm Hg, maximum 52.7 ± 9.9 mm Hg; p < 0.01). Similar changes were observed in effective arterial elastance (control 2.00 ± 0.75 mm Hg/ml, midpoint 1.60 ± 0.53 mm Hg/ml, maximum 1.31 ± 0.46 mm Hg/ml; p < 0.01). Although the decrease in end-systolic elastance at midpoint (control 3.08 ± 1.61 mm Hg/ml, midpoint 2.92 ± 1.68 mm Hg/ml) did not reach statistical significance, end-systolic elastance significantly decreased at maximum (2.63 ± 1.46 mm Hg/ml; p < 0.01). Continuous measurements showed that the decreases in mean arterial pressure and effective arterial elastance always preceded the depression of end-systolic elastance and that afterload reduction by vasodilating effect of protamine was the mechanism most likely to have initiated the hypotension. Delayed decrease in contractility may be ascribed to reduced coronary perfusion pressure caused by vasodilation or to a direct effect of protamine. (J Thorac Cardiovasc Surg 1996;112:462-71)

A simplified Manouguian's aortic annular enlargement for aortic valve replacement with prosthetic valve was performed in a patient with severe aortic stenosis and mild regurgitation by preserving both the anterior mitral leaflet and the left atrial roof intact. This method minimized the operative risk by avoiding injury to the mitral valve, while inserting a possibly two-size-larger prosthetic valve. The inserted prosthetic valve was positioned parallel to the original aortic valve. Moreover, the incision from the top of the commissure between the non-coronary cusp and left coronary cusp through the interventricular fibrous trigone appears to be easily extended into the exact center of the anterior mitral leaflet if further enlargement is required.

Although Manouguian's operation is well established, there have been little long-term data published on its outcome. From January 1980 to June 1988, 15 patients underwent patch enlargement of the small aortic anulus by Manouguian's approach, either with aortic single valve replacement (7 patients) or with aortic-mitral double valve replacement (8 patients). Follow-up ranged from 3.0 to 11.4 years (mean 8.5) and was completed with a cumulative total of 102 patient-years. One patient died of fulminant hemolysis, probably related to turbulent jet flow and Dacron patch material (operative mortality 6.7%). There were four late deaths, and the actuarial survival, including operative death at 10 years, was 62% +/- 14%. Reoperations were performed seven times in six patients. Most of these complications were not considered to be caused by the anulus-enlarging procedure. Actuarial freedom rate from reoperation at 10 years was 65% +/- 15%. Four patients underwent rereplacement of prostheses for Hancock valve failure during 2.9 to 11.3 years (mean 8.2 years). The anulus enlargement was found to be well healed and presented no problem during reoperation. Surgically induced mitral regurgitation by Manouguian's procedure was observed in two patients. The regurgitation did not progress during follow-up duration of 1.9 to 10.0 years, nor did it cause congestive heart failure. Annular enlargement by Manouguian's procedure with use of mechanical valves is one of the good selections in patients with the narrow aortic valve ring.

From February 1975 through October 1981, 256 Hancock porcine bioprostheses (JohnsonJohnson Cardiovascular, King of Prussia, Pa.) (60 aortic, 169 mitral, and 27 pulmonary/tricuspid position) were implanted in 220 patients (104 male and 116 female, aged 9 to 67 years; mean 43.3) at Kyushu University Hospital in Japan. The procedures include 41 aortic valve replacements, 121 mitral valve replacements, 4 pulmonary valve replacements, 6 tricuspid valve replacements, and 48 combined valve replacements (31 aortic plus mitral, 13 mitral plus tricuspid, and 4 aortic plus mitral plus tricuspid). Hospital mortality was 6.4%. Follow-up was 98% during 8 to 14 (mean 10.5) years. Cumulative follow-up was 1836 patient-years and 2078 valve-years. At 10 years the overall actuarial survival rate, including hospital morality, was 70% +/- 3%, and freedom from valve-related mortality with sudden death was 87% +/- 3%. More than half of the current survivors required no anticoagulant therapy. Freedom from thromboembolism or anticoagulant-related hemorrhage (or both) and prosthetic valve endocarditis was common. Freedom from structural valve failure and reoperation declined more than 9 years after replacement of left-sided heart valves but not after replacement of right-sided heart valves. Sixty-seven patients underwent 68 repeat operations, and there were four deaths (5.9%). The rate of freedom from overall valve-related complications at 10 years was 62% +/- 8% for aortic valve replacement, 53% +/- 5% for mitral valve replacement, 80% +/- 13% for pulmonary/tricuspid valve replacement, and 42% +/- 9% for combined valve replacement. There was a significant difference between pulmonary/tricuspid valve replacement and combined valve replacement (p less than 0.05). The Hancock bioprosthesis is suitable for the replacement of valves in the right side of the heart but not for combined valve replacement.

Comparative long-term performance characteristics of St. Jude Medical (SJM) and bioprosthetic valves were conducted retrospectively for patients who underwent prosthetic valve replacement in the right side of the heart from 1975 to 1988. Fifty-four patients received either SJM (n = 18) or bioprosthetic (n = 37) valves. The cumulative follow-up for SJM valves was 91 valves-years (range 3.9 to 7.2 years) and that for bioprostheses was 282 valve-years (range 1.3 to 14.8 years). Follow-up rate was 100%. The actuarial survival rate excluding hospital deaths at 5 years was 81 +/- 10% for SJM and 97 +/- 3% for bioprosthetic valve recipients (p = ns). The rates of freedom from thrombosis or anticoagulant-related hemorrhage, structural valve failure, prosthetic valve endocarditis, reoperation, and overall valve-related complications at 5 years were 72 +/- 11%, 100%, 100%, 83 +/- 9%, and 72 +/- 11% for SJM valve recipients, and 100%, 97 +/- 3%, 97 +/- 3%, 94 +/- 4%, and 94 +/- 4% for bioprosthetic valve recipients, respectively. Structural valve failure, prosthetic valve endocarditis and reoperations occurred at a similar incidence in each of the two types of prostheses. Thrombosis and overall valve-related events occurred more frequently in SJM valve recipients (5.5 +/- 2.5 vs 0%/valve-year; p less than 0.02, 6.6 +/- 2.7 vs 1.1 +/- 0.6 %/valve-year; p less than 0.03, respectively). The bioprosthetic valve which did not need warfarin anticoagulation therapy had low incidence of valve-related complications and showed good long-term durability even in the younger age group. The bioprosthetic valve was superior to the SJM valve in the right side of the heart.

From May 1975 through December 1988, 91 patients (mean age 50.4 +/- 12.8 years) had first-time surgery for mitral pure regurgitation; 48 had mitral valve replacement (MVR) and 43 had valve repair. A majority of the patients had non-rheumatic valvular diseases. Those patients who underwent repair had less hemodynamic and functional derangement than those who underwent MVR. The operative mortality was 8.3% in the MVR group and 2.3% in the repair group. Seventeen percent of the MVR group and 2% of the repair group required intra-aortic balloon pumping support (p less than 0.03). A higher dose of dopamine and/or dobutamine during the early postoperative period was necessary in the MVR group (7.0 +/- 4.8 micrograms/kg/min) than in the repair group (5.1 +/- 3.1 micrograms/kg/min). Duration of respirator support for hospital survivors was longer in the MVR group (2.3 +/- 2.7 days) than in the repair group (1.4 +/- 1.0 days). There were 5 late deaths (2.2 +/- 1.0%/pt-yr) not counting 6 non-cardiac deaths in the MVR group and 1 (0.6 +/- 0.6%/pt-yr) in the repair group. There were 17 patients (7.5 +/- 1.8%/pt-yr) who experienced treatment failure in the MVR group and 5 (2.3 +/- 1.3%/pt-yr) in the repair group (p less than 0.02). Eight patients in the MVR group (3.5 +/- 1.3%/pt-yr) underwent repeat surgery in the late postoperative period, as did 3 (1.7 +/- 1.0%/pt-yr) in the repair group. There was no increase in the incidence of repeat surgery after valve repair. All the current survivors in the repair group, and 96% of those in the MVR group were in NYHA functional class I or II. These results indicate that mitral repair is the preferred operative procedure for pure mitral regurgitation, whenever it is possible.

Isolated rat heart preparations were used to determine the effect of cardioplegia on myocardial metabolism during profound hypothermic (15 degrees C) ischemia. The hearts were grouped according to the components of cardioplegia and the mode of administration. The six groups were normokalemic (GI), calcium-containing hyperkalemic (GII), calcium-free hyperkalemic (GIII) and single dose (A), multidose (B). Following 120 min of ischemia, tissue ATP decreased from 25.4 +/- 2.2 to 10.3 +/- 2.7, 3.9 +/- 2.4, 4.1 +/- 1.2, 15.5 +/- 3.2, 14.5 +/- 2.4 and 20.0 +/- 2.7 (I-A vs II-A p less than 0.005, I-A vs III-A p less than 0.005, I-B vs III-B p less than 0.05, II-B vs III-B p less than 0.005), and tissue lactate increased from 9.6 +/- 1.5 to 163.4 +/- 12.0, 174.1 +/- 13.5, 166.8 +/- 21.3, 99.1 +/- 8.3, 102.6 +/- 12.2 and 83.5 +/- 9.3 (I-B vs III-B p less than 0.02, II-B vs III-B p less than 0.02) mumol/dry wt g, in GI-A, GII-A, GIII-A, GI-B and GII-B, respectively. The results of this study suggests that (1) potassium cardioplegia in a single dose does not prevent degradation of high energy phosphate (HEP) in the hypothermic arrested heart, (2) though multidose cardioplegia is effective in preserving HEP during ischemia, the extent of its effects varies with the composition, and (3) the omission of calcium is beneficial in GIK cardioplegia in terms of preserving HEP at the end of ischemia.

A randomized, prospective study of the effectiveness of preoperative administration of coenzyme Q10 on the prophylaxis of postoperative low cardiac output state was performed in 50 patients with acquired valvular diseases necessitating valve replacement. There were 25 patients in the treatment group and 25 in the control group. Patients in the treatment group received 30 to 60 mg of coenzyme Q10 orally for six days before operation. Preoperative clinical variables, operative procedures, total cardiopulmonary bypass time, and aortic cross-clamping time were similar for the two groups. Postoperatively, mild to severe low cardiac output state developed in 28 of 50 patients (56%) and necessitated the administration of considerable amounts of inotropic agent. The treatment group showed a significantly lower incidence of low cardiac output state during the recovery period than the control group (p less than 0.05). These results suggest that preoperative administration of coenzyme Q10 will increase the tolerance of human hearts to ischemia during aortic cross-clamping.

Two solutions, our cardioplegic solution and Collins’ solution, were tested with regard to preservation of the heart under deep hypothermia before transplantation. The setup used was the isolated perfused working rat heart model and 4 hours of preservation at 0° C. The following three groups were prepared: Group 1: the heart was arrested with the cardioplegic solution (potassium: 20 mmol/L, sodium: 87 mmol/L) and then flushed with and stored in Collins’ solution (potassium: 117 mmol/L, sodium: 10 mmol/L); Group 2: the heart was arrested with and stored in Collins’ solution; and Group 3: the heart was arrested with and stored in the cardioplegic solution. The recovery of cardiac function was more satisfactory in Group 1 than in Groups 2 and 3. The increase in lactate was greater, and adenosine triphosphate and total adenine nucleotide were more depleted during storage in Group 2 than in Groups 1 and 3. In Group 3 myocardial sodium accumulation and potassium depletion during storage were greater than in Groups 1 and 2, and myocardial sodium and calcium overload after reperfusion were greater than in Group 1. Myocardial calcium overload after reperfusion in Group 2 was also greater than that in Group 1. These findings plus coronary vascular resistance analysis revealed that Collins’ solution damages the heart during arrest procedures and that the cardioplegic solution is less effective for storage of the arrested heart under deep hypothermia. Therefore the heart should be first arrested with the cardioplegic solution and then flushed with and kept in Collins’ solution for simple cold storage.

The effects of complete right bundle branch block (CRBBB) on the early postoperative course and long-term follow-up results of closure of ventricular septal defect (VSD) were investigated. (1) Postoperative change in cardiothoracic ratio (CTR): In patients whose ratio of total pulmonary resistance to total systemic resistance (Rp/Rs) was > 0.33, CTR of the group with CRBBB did not decrease significantly (p > 0.1) but CTR of the group without CRBBB was improved markedly (p

A retrospective study of 21 adult patients with tetralogy of Fallot (TOF) was undertaken to determine the predisposing risk factors of renal dysfunction following total correction of the disease. Five of the 21 patients exhibited moderate-to-severe postoperative azotemia and an additional five exhibited mild azotemia. Significant risk factors for postoperative renal dysfunction found in routine preoperative examinations were as follows: arterial oxygen saturation of less than 90%, cardiothoracic ratio (CTR) of greater than 50%, mean electrical axis of the QRS complexes of greater than +120 degrees, S wave in Lead V6 of greater than 7 mm, R/S voltage ratio in Lead V6 of less than 2, and negative T wave in Lead V6. In addition, preoperative cardiac catheterization data showed that the patients exhibiting postoperative azotemia had more severe pulmonary stenosis, a smaller pulmonary-to-systemic flow ratio (Qp/Qs), and a larger left ventricular cavity than nonazotemic patients. The incidence of postoperative low cardiac output state (LOS) was significantly higher in the azotemic patients. These findings suggest that a combination of the severe form of TOF and a large left ventricle increase susceptibility to LOS and postoperative renal dysfunction. The cause and the clinical significance of the large left ventricular cavity in adults with TOF are discussed.

In 12 dogs being supported by cardiopulmonary bypass, the relationship among myocardial oxygen consumption and four energy-consuming factors (basal metabolism, heart rate, tension development, and external work) was studied. Tension (internal work) in the left ventricular wall was evaluated by myocardial tissue pressure with a Mikro-Tip pressure transducer. In an empty beating heart with constant perfusion pressure, both systolic tissue pressure and developed tissue pressure represented the same characteristics as developed tension measured by other methods. As the heart rate was increased, the systolic tissue pressure and developed tissue pressure continued to increase stepwise (Bowditch effect) up to some stimulation rate, at which, however, a decrease began despite a further increase in heart rate (Woodworth effect). Significant regression was established between myocardial oxygen consumption and heart rate, tension (developed tissue pressure x heart rate), and external work (minute work): myocardial oxygen consumption = (9.05 x 10(-3) heart rate) + (1.95 x 10(-4) developed tissue pressure) x heart rate + (1.63 x 10(-3) minute work) + 1.42 (r = 0.7999), where activation energy = 9.05 x 10(-3) ml/100 gm per beat, tension-related energy = 1.95 x 10(-4) ml/100 gm per unit of internal work, energy for work = 1.63 ml/100 gm per unit of external work, and basal metabolism = 1.42 ml/min/100 gm. We concluded that myocardial tissue pressure is a good substitute for tension and that multiple regression with heart rate, tension, and external work (as by modified Fenn's equation) seems indispensable to predict myocardial oxygen tension in the whole heart.

The lack of adequate myocardial preservation because of maldistribution of cardioplegic solution in coronary artery disease remains a perplexing problem. We compared two methods of cardioplegic delivery in dogs: antegrade aortic root perfusion (Group I) and retrograde coronary sinus perfusion (Group II). Metabolic changes and regional function in the coronary occlusion model, in which the left anterior descending artery was occluded at its prediagonal portion, were studied. In the distribution of the occluded coronary artery, adenosine triphosphate and total adenine nucleotides at the end of 120 minutes of ischemia were preserved better in Group II (16.80 and 22.94 mumol/gm dry weight) than in Group I (11.06 and 16.19 mumol/gm dry weight, p less than 0.05). Lactate accumulation tended to be higher in Group I than in Group II (114.0 and 87.2 mumol/gm dry weight, respectively; not significant). Percent recovery of segmental shortening was also better in Group II than in Group I (100% and 22.3% at the same left atrial pressure, 4 mm Hg; p less than 0.01). In the region supplied by the intact coronary artery, there were no significant differences between the two groups with regard to metabolic changes and regional function. These observations suggest that retrograde cardioplegic perfusion via the coronary sinus is preferable for surgically treatment of severe coronary artery disease.

Myocardial distribution of the retrograde flow through the coronary sinus in the canine heart was evaluated by observing the corrosion casts of the myocardial vessels after coronary sinus injection of a low-viscosity resin, Mercox, a compound that passes through capillaries. The apex and the left ventricular free wall were well perfused at the microvascular level, even in the presence of complete left main coronary artery occlusion, whereas the right ventricular free wall was not perfused effectively at this level in any heart. Although there was considerable variation in the perfusion of the ventricular septum from heart to heart, the entire septum was not perfused in some of the hearts. We considered this poor perfusion of the septum to be due to the presence of well-developed thebesian veins in the septum. Retrograde coronary sinus perfusion of cardioplegic solution may be a valuable alternative to protect the left ventricular free wall, especially in cases of critical coronary artery stenosis or occlusion. However, antegrade perfusion should be used also, whenever possible, for adequate protection of the septum and the right ventricular free wall.

Using a method of our own design, we evaluated intraoperatively the function of prosthetic heart valves. The changing hemodynamics induced by a stress test were assessed by simultaneously measuring the mean transvalvular pressure gradient and the stroke volume. The effective orifice area (EOA) of the valves was determined for each stroke by computer analysis, and this value was compared with the actual orifice area. Data were collected from 19 patients undergoing aortic or mitral valve replacement or both with 17 St. Jude Medical and 12 Ionescu-Shiley valves. The mean pressure gradient increased with tachycardia and an increase in mean left atrial pressure in the mitral position, but decreased with a decrease in cardiac output and peak left ventricular pressure in the aortic position. The St. Jude Medical valve had a smaller mean pressure gradient than the Ionescu-Shiley bioprosthesis. For both valves, the EOA increased with valve size. The St. Jude Medical valve had a greater EOA than the Ionescu-Shiley bioprosthesis, regardless of the valve size (p less than 0.005). However, the performance of prosthetic leaflets was better with the Ionescu-Shiley bioprosthesis than with the St. Jude Medical mechanical valve (p less than 0.001). This method involving computer analysis of each cardiac cycle proved to be useful for evaluating prosthetic heart valve function in the presence of changing hemodynamics.