Search PubMed⌕ Search

Biomedical subjects

M Oe

Publications and source records attributed to M Oe.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of preserving mitral apparatus on ventricular systolic function in mitral valve operations in dogs.

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.

Animals↗
PubMed1991

Comparative study between valve repair and replacement for mitral pure regurgitation--early and late postoperative results.

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.

Actuarial Analysis↗
PubMed1991

Beneficial effect of pericardial meshing on left ventricular pump performance in dogs.

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.

Animals↗
PubMed1991

Superior protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium. Clinical study in comparison with St. Thomas' Hospital solution.

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 ischemia (11.5 degrees C +/- 3.1 degrees C versus 9.3 degrees C +/- 3.2 degrees 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 less than 0.005), and bradyarrhythmias were significantly more prevalent in group II (6.3% versus 44.4%; p less than 0.05). Serum creatine kinase MB activity at 15 minutes of reperfusion (12.3 +/- 17.0 IU/L versus 42.6 +/- 46.1 IU/L; p less than 0.05) and the dose of dopamine or dobutamine required during the early phase of reperfusion (1.8 +/- 2.5 micrograms/kg/min versus 6.1 +/- 3.3 micrograms/kg/min; p less than 0.0002) were both significantly greater in group II. Postischemic left ventricular function, as assessed by percent recovery of the left ventricular end-systolic pressure-volume relationship in patients who underwent aortic valve replacement alone, was significantly better in group I (160.4% +/- 45.5% versus 47.8% +/- 12.9%; p less than 0.05). Serum level of calcium and magnesium ions was significantly lower in group I. Thus low-calcium, magnesium-free potassium cardioplegic solution provided excellent protection of the ischemic heart, whereas St. Thomas' Hospital solution with calcium and magnesium enabled relatively poor functional and electrical recovery of the heart during the early reperfusion period. These results might be related to differing levels of extracellular calcium and magnesium on reperfusion.

Arrhythmias, Cardiac↗
PubMed1990

Comparative study of cell saver and ultrafiltration nontransfusion in cardiac surgery.

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.

Adult↗
PubMed1990

The mechanism of protective effect of diltiazem on reperfusion-induced arrhythmias in isolated rat heart.

This investigation was undertaken to define the mechanism by which diltiazem protects against life-threatening, reperfusion-induced arrhythmias. Using an isolated retrogressively perfused rat heart preparation with transient coronary artery occlusion, we compared the effects of diltiazem in its active form (d-cis) to its stereo-isomer (1-cis). Pre-ischemic administration of d-diltiazem (5 x 10(-8), 5 x 10(-7), 5 x 10(-6) M) caused a dose-dependent reduction in ventricular arrhythmias upon reperfusion following 10 min of regional ischemia. The incidence of reperfusion-induced ventricular fibrillation (RVF) was 50%, 0% (p less than 0.05) and 0% (p less than 0.05) with 5 x 10(-8), 5 x 10(-7), 5 x 10(-6) M diltiazem, respectively, compared with 60% in the control group. Preischemic administration of the 1-isomer caused different dose-dependent reduction in RVF. With 5 x 10(-6) M, the 1-isomer also reduced the incidence of RVF to 0% (p less than 0.05). However below this concentration it was ineffective (67%). D-diltiazem (5 x 10(-7) and 5 x 10(-6) M) increased coronary flow from 11.5 +/- 1.9 ml/min to 15.3 +/- 1.6 ml/min (p less than 0.05) and 15.2 +/- 1.0 ml/min (p less than 0.05) respectively, prior to ischemia. In contrast, the same dose of the 1-isomer did not alter coronary flow. The highest dose (5 x 10(-6) M) of d-diltiazem decreased heart rate by approximately 30% during the reperfusion phase, but all other concentrations had no significant effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

A new method of retrograde cardioplegic administration. Right ventricular protection by right atrial perfusion cooling.

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 degrees 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 degrees C in group I and 20 degrees 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 +/- 2.34 mumol/gm dry weight, p less than 0.05). The percent recovery of right ventricular contractility, which was evaluated by end-systolic pressure-volume relationships, was significantly better in group I at each reperfusion period (30 minutes: 130.0% +/- 9.6% versus 86.1% +/- 11.8%, p less than 0.05; 60 minutes: 159.6% +/- 12.9% versus 96.5% +/- 20.1%, p less than 0.05). Postischemic right ventricular stiffness (reciprocal value of compliance) increased in group II compared with group I, although the difference was not statistically significant. There were no major differences in percent recovery of the left ventricular end-systolic pressure-volume relationships between the two groups. The evidence suggests that the right atrial perfusion cooling method produces excellent right ventricular protection.

Animals↗
PubMed1990

Effects of left heart bypass on right ventricular performance. Evaluation of the right ventricular end-systolic and end-diastolic pressure-volume relation in the in situ normal canine heart.

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 less than 0.02) and thus had a deleterious influence on right ventricular performance. The left heart bypass, on the other hand, had a counteracting beneficial influence on right ventricular performance through the increase in chamber compliance (38% +/- 5%, p less than 0.01) and the decrease in pulmonary arterial input resistance (-15% +/- 12%, p less than 0.01). The net effect of the left heart bypass was the increase in cardiac output (20% +/- 2%, p less than 0.05) for any given right ventricular end-diastolic pressure. We conclude that in normal hearts the left heart bypass augments right ventricular performance. We ascribe these beneficial effects to diastolic ventricular interdependence and afterload unloading.

Animals↗
PubMed1989

[Myocardial protection during transplantation procedure following cold storage in Collins' solution].

The purpose of this study is to evaluate the myocardial protective effects of two types of solution during heart transplantation procedure following cold storage in Collins' solution. Based on the concept whether the ischemic time during the procedure is an extension of heart storage or is an usual aortic cross-clamped ischemic time, we compared the effects of our cardioplegic solution (Group I) and Collins' solution (Group II) using isolated working rat heart model. After 30 minutes of global ischemia at 25 degrees C following 2 hours of cold storage, the hearts in Group I exhibited better functional recovery than those in Group II (% recovery of cardiac output was 61.1 +/- 5.4% in Group I and 42.4 +/- 7.4% in Group II, p less than 0.01). In Group II, marked elevation of coronary vascular resistance occurred on reperfusion. CPK release during reperfusion period was greater in Group II (0.41 +/- 0.24 IU/15 min/heart in Group I, 1.92 +/- 1.25 IU/15 min/heart in Group II, p less than 0.01). Myocardial metabolites contents (ATP, TAN, creatine phosphate and lactate) and energy charge were not significantly different between two groups. We conclude that it is harmful to ischemic myocardium to use Collins' solution as myocardial protection during transplantation procedure even if following cold storage in Collins' solution.

Animals↗
PubMed1989

[Clinical assessment of prosthetic valve replacement of the right-sided cardiac valves: mechanical or bioprosthesis?].

Clinical results with mechanical and bioprosthetic valve replacements for tricuspid and/or pulmonary positions were reviewed. Between February 1975 and December 1985, 34 bioprostheses (B) (22 Hancock, 9 Ionescu-Shiley and 3 Carpentier-Edwards pericardial) and 18 mechanical prostheses (M) (St. Jude Medical) were implanted in our institute excluding hospital death. Group with B included 29 tricuspid valve replacements and 5 pulmonary valve replacements. Group with M included 9 tricuspid valve replacements, 7 pulmonary valve replacements and 1 both valve replacements. The cumulative follow-up period was 207.2 patient-years (p-t) in group B and 55.0 p-y in group M. The incidence of valve failure was 0.48 +/- 0.48% per p-y in group B and 7.27 +/- 3.64% per p-y in group M (p less than 0.001). The incidence of valve-related events was 1.93 +/- 0.97% per p-y in group B and 9.09 +/- 4.07% per p-y in group M (p less than 0.001). At 3 years, the percent free of valve failure was 100 +/- 0% in group B and 76.8 +/- 10.2% in group M (p less than 0.05). Fourteen bioprosthetic valves (B') and 10 mechanical valves (M') were implanted at the right-sided cardiac valve position alone. The cumulative follow-up period was 94.2 p-y in group B' and 32.3 p-y in group M'. The incidence of valve-related events was 1.06 +/- 1.06% per p-y in group B' and 12.4 +/- 6.19% per p-y in group M' (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Effects of open-heart surgery on renal function].

Effects of open-heart surgery on renal function were studied in 38 patients who had uneventful postoperative course with no sign of acute renal failure. Of these, 19 underwent aorto-coronary bypass grafting (Group 1) and 19 underwent valve replacement (Group 2). During cardiopulmonary bypass (CPB), renal plasma flow (RPF) and glomerular filtration rate (GFR) significantly decreased in both groups as compared to the preoperative values. The decreased GFR remained significantly low on the day of operation in both groups and returned to the preoperative level on the 1st postoperative day (POD) in group 1 and on the 3rd POD in group 2. On the other hand, plasma antidiuretic hormone (ADH) level markedly increased during CPB and remained significantly higher than the preoperative level through the 1st POD. Despite the decreased GFR and increased ADH, however, urinary flow markedly increased during CPB in both groups and remained at significantly higher level than the preoperative values through the 3rd POD in group 1 and through the 5th POD in group 2. Fractional excretion of sodium significantly increased during CPB in both groups and remained high through the 1st POD in group 1 and through the 3rd POD in group 2. These data demonstrate that the renal function of urine concentration is disturbed in the early phase following open-heart surgery even in the patients who have uneventful postoperative course.

Adult↗