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Biomedical subjects

M J Buckley

Publications and source records attributed to M J Buckley.

At least 163 records · Page 9Linked to original sources
PubMed1981

Mitral valve replacement for isolated mitral regurgitation: analysis of clinical course and late postoperative left ventricular ejection fraction.

One hundred five patients underwent mitral valve replacement for relief of isolated mitral regurgitation between 1974 and 1979. There were 4 in-hospital deaths (4 percent) and 12 late deaths giving an 82 percent predicted 5 year survival rate. An age of 60 years or more at the time of surgery and a preoperative left ventricular ejection fraction of less than 0.40 were the only variables that correlated with decreased survival at 3 to 5 years after operation (p less than 0.05). Postoperatively, 87 (98 percent) of 89 long-term survivors were in New York Heart Association functional class I or II (68 in class I and 19 in class II). Survival did not differ between patients with porcine versus mechanical valve replacement, but patients with a mechanical valve had a greater incidence of postoperative cerebrovascular accident (8.6/100 patient years) than did patients with a porcine valve (2.8/100 patient years) (p less than 0.002). Ejection fraction at rest was determined with multigated cardiac imaging 12 to 75 months postoperatively in 34 of 89 long-term survivors. The mean preoperative ejection fraction was 0.62 +/- 0.09 (mean +/- 1 standard deviation) and the mean postoperative ejection fraction was 0.50 +/- 0.15 (p less than 0.001). When the preoperative value was compared with the postoperative value at rest the ejection fraction increased by 0.10 or more in 1 patient (3 percent), remained within +/- 0.09 of the preoperative value in 12 patients (35 percent) and decreased by 0.10 or greater in 21 patients (62 percent). Sixteen (94 percent) of 17 patients whose postoperative ejection fraction was greater than 0.50 were in functional class I postoperatively compared with 11 (65 percent) of 17 patients whose postoperative ejection fraction was 0.50 or less (p less than 0.05). No preoperative factor, including preoperative ejection fraction or cardiothoracic ratio, predicted the postoperative ejection fraction. A postoperative exercise ejection fraction was obtained in 29 patients, and an abnormal ejection fraction change with exercise (increase less than 0.05) was observed in 20 patients (69 percent). Patient age at the time of study correlated inversely with the change in ejection fraction from rest to exercise; no other variables were predictive. It is concluded that, in addition to age, only preoperative left ventricular function as measured by ejection fraction predicts survival in patients undergoing mitral valve replacement for isolated mitral regurgitation. Clinical recovery is good even though the majority of long-term survivors have a postoperative decrease in ejection fraction.

Aged↗
PubMed1981

Correlation of patterns of subendocardial reperfusion and left ventricular performance after ischemia.

Ninety-three dogs were studied with normothermic or hypothermic ischemia for 60 or 90 minutes, with or without potassium cardioplegia. Radioactive-labeled microspheres (9 +/- 1) were injected into the aortic perfusion cannula just prior to aortic cross-clamping and at 2, 6, and 10 minutes after the clamp was released. Left ventricular (LV) function was analyzed with a right heart bypass model before and 45 minutes after the ischemia period. Changes in LV function were defined as the arithmetic difference in the center of mass between preischemia and postischemia computer-drawn Sarnoff curves. Regardless of technique of myocardial protection, increased subendocardial flow 2 minutes after ischemia correlated strongly with preservation of LV function (p less than 0.01). Well-preserved hearts showed a rapid return to normal levels of coronary blood flow (p less than 0.01). In contrast, a delay in the peaking of subendocardial flow to 10 minutes was associated with poor function (p less than 0.01). There was a high correlation between ultrastructural morphology and LV function. While well-preserved hearts showed early preferential subendocardial perfusion, the poorly protected myocardium is unable to restore adequate subendocardial flow early in the reperfusion period.

Animals↗
PubMed1981

Acute traumatic disruption of the thoracic aorta: a ten-year experience.

During a ten-year period, 44 patients were treated for acute traumatic disruption of the thoracic aorta. Of the 44 patients, 21 had operative repair within 48 hours of injury (Group 1); 14 patients had operative therapy electively delayed for 2 to 79 days (Group 2); 5 had operative therapy electively delayed indefinitely (Group 3); 2 had immediate operative repair when a delayed diagnosis was made at 21 and 56 days, respectively (Group 4); 1 patient died during angiography and 1 refused operation (Group 5). Mortality was as follows: Group 1, 24%; Group 2, 14% Group 3, 0; Group 4, 100%; and Group 5, 100%. All operative deaths occurred in the subgroup of 23 patients in whom left heart bypass was utilized. Immediate operative intervention with a heparinized shunt is preferable as soon as the diagnosis of thoracic aortic disruption has been established, but elective delay of operation in patients with severe concomitant injuries can be achieved safely with beta blockade and antihypertensive therapy.

Accidents, Traffic↗
PubMed1981

Plasma vasopressin levels and urinary sodium excretion during cardiopulmonary bypass with and without pulsatile flow.

The use of pulsatile perfusion during bypass should create a more physiological milieu and thus attenuate the vasopressin stress response. To determine this, 20 patients scheduled for elective coronary artery bypass operation were studied in two groups. Group 1 had a standard nonpulsatile perfusion, and in Group 2 a pulsatile pump was used. Measurements were made before and after anesthesia, after surgical incision, and at 15 and 30 minutes during and after cardiopulmonary bypass. In both groups, vasopressin levels were significantly elevated after sternotomy (4.5 +/- 1.5 to 37 +/- 10 pg/ml in Group 1 and 3.1 +/- 1.2 to 33 +/- 9 pg/ml in Group 2, p less than 0.05) and during bypass (198 +/- 19 pg/ml in Group 1 and 113 +/- 16 pg/ml in Group 2) but were higher in Group 1 (p less than 0.05). With comparable perfusion pressures in both groups, Group 2 required higher flow (4.2 +/- 0.2 versus 3.5 +/- 0.3 L/min, p less than 0.05) and had lower resistance (1,351 +/- 182 versus 1,841 +/- 229 dynes sec cm-5, p less than 0.05) and higher urine Na+ (123 +/- 5 versus 101 +/- 8 mEq/L, p less than 0.05). These data demonstrate that pulsatile flow can significantly attentuate the vasopressin stress response to bypass. Since vasopressin, at these concentrations, is a potent vasoconstrictor and is capable of producing a Na+ diuresis, this may partially explain the higher flow requirements and the decrease in Na+ excretion.

Blood Pressure↗
PubMed1981

Aortocoronary bypass grafting in patients without left main stenosis. Relation of risk factors to early and late survival.

Three-hundred and thirty-five patients without left main stenosis or recent acute myocardial infarction underwent isolated aortocoronary bypass grafting during 1974 and 1975. The hospital mortality was 2 per cent for the four-year predicted survival is 94 per cent. Neither the preoperative presence or absence of a progressive or unstable angina pattern, the extent of coronary artery disease, nor the left ventricular ejection fraction predicted postoperative survival. None of the 25 patients whose ejection fraction was 0.30 or less died in the perioperative period, and no late deaths occurred in this subgroup until after 36 months of follow-up, giving a predicted four-year survival rate of 82 per cent. With only one exception, patients in this subgroup were operated on because of angina, which was unstable in three-quarters of them. We believe that this study shows that patients with a severely reduced ejection fraction should not be refused aortocoronary bypass grafting if symptoms of angina are severe and predominate over symptoms of heart failure.

Coronary Artery Bypass↗
PubMed1981

Ventricular septal rupture: a review of clinical and physiologic features and an analysis of survival.

Forty-one patients with postinfarction ventricular septal rupture were cared for in our hospital during 1971-1975. Cardiogenic shock developed after septal rupture in 55% of these patients. Shock was unrelated to site of infarction, extent of coronary artery disease, left ventricular ejection fraction, or pulmonary-to-systemic flow ratio, but mean pulmonary artery pressure was lower in shock than in nonshock patients. These observations suggest that shock was produced mainly by right ventricular impairment. Perioperative survival was much higher in patients who did not have shock preoperatively (14 of 17 [82+]) than in those who did (three of 11 [27%]). Magnitude of shunt, left ventricular ejection fraction, extent of coronary artery disease, and performance of aortocoronary bypass grafting were not distinctly correlated with perioperative survival. After a minimum 4-year follow-up, 76% of the perioperative survivors are alive, and none suffer more than New York Heart Association functional class II disability. All 13 unoperated patients (11 in shock) died within 3 months.

Aged↗
PubMed1981

Attenuation of the stress response to cardiopulmonary bypass by the addition of pulsatile flow.

The effect of pulsatile flow during cardiopulmonary bypass on the hormonal stress response was studied in 26 patients. Thirteen had routine and 13 had pulsatile bypass with an average pulse pressure of 30 mm Hg. Plasma vasopressin levels were significantly elevated during bypass in both groups, but were lower with pulsation (66 +/- 11 vs 36.3 pg/ml, p less than 0.05). Epinephrine levels increased in both groups during bypass, but were higher after bypass (1179 +/- 448 vs 713 +/- 140 pg/ml, p less than 0.05) and in the recovery room (1428 +/- 428 vs 699 +/- 155 pg/ml, p less than 0.05) in the nonpulsatile group. The same response was noted in the norepinephrine levels (924 +/- 225 vs 465 +/- 90 pg/ml, p less than 0.05; 1015 +/- 491 vs 717 +/- 112 pg/ml, p less than 0.05). There were no significant changes in renin activity in either group, but the increase after cardiopulmonary bypass was greater in the nonpulsatile group (2.0 +/- 0.7 vs 1.36 +/- 0.4 ng/ml/hr, NS). These data suggest that pulsatile flow significantly attenuates the vasopressin and catecholamine stress response to cardiopulmonary bypass. This may explain the increased flow requirements and better tissue perfusion and organ function and the decreased incidence of postoperative hypertension after bypass using pulsatile flow.

Blood Gas Analysis↗
PubMed1981

Intraaortic balloon counterpulsation in a community hospital.

Our experience with intraaortic balloon counterpulsation in 41 patients documents the feasibility of a coordinated aggressive therapeutic approach in patients with potentially fatal complications of coronary artery disease. The use of intraaortic balloon pump in a non-cardiac surgical center has allowed hemodynamic support in the critically ill, safety in angiography, appropriate selection of patients for surgery, and safe transportation to a cardiac surgery center when indicated.

Adult↗
PubMed1981

The effect of pulsatile perfusion on preservation of left ventricular function after aortocoronary bypass grafting.

Pulsatile perfusion has been reported to be of value in intraoperative myocardial protection. To evaluate this technique, we studied 26 patients undergoing aortocoronary bypass grafting. Ejection fraction determinations from multigated cardiac blood pool scans, serial hemodynamic monitoring, and total CPK and MB-CPK sampling were performed early (4, 6 and 8 hours after bypass) and 10 days after operation. In 12 patients, pulsatile perfusion was started immediately after aortic cannulation and continued until 10 minutes after cessation of bypass; 14 patients had standard nonpulsatile perfusion. All patients had a single aortic cross-clamping and potassium cardioplegia. Cross-clamp time (46 +/- 3 and 46 +/- 3 minutes [+/- SEM]), total bypass time (94 +/- 4 and 89 +/- 6 minutes), and mean perfusion pressure (82 +/- 5 and 83 +/- 3 mm Hg) were comparable in the pulsatile and nonpulsatile groups, respectively, as were extent of coronary disease and number of bypass grafts. Preoperative and postoperative ejection fractions for pulsatile and nonpulsatile groups, respectively, were 0.57 +/- 0.03 and 0.55 +/- 0.04 before operation, 0.37 +/- 0.03 and 0.40 +/- 0.04 4 hours after bypass, 0.40 +/- 0.03 and 0.46 +/- 0.04 at 6 hours, 0.51 +/- 0.05 and 0.52 +/- 0.07 at 8 hours and 0.56 +/- 0.05 and 0.53 +/- 0.04) 10 days after operation. Mean arterial pressure, left atrial pressure and serial cardiac indexes were similar in both groups. There were no perioperative myocardial infarctions by ECG in either group. Total CPK (586 +/- 78 and 617 +/- 140 IU/l) and peak MB-CPK (73 +/0 14 and 61 +/- 11 IU/l) were comparable in the pulsatile and nonpulsatile groups, respectively. Pulsatile perfusion offers no advantage in myocardial preservation after aortocoronary bypass grafting in patients with normal left ventricular function.

Coronary Artery Bypass↗
PubMed1981

Hemodynamic and clinical evaluation of the Hancock modified-orifice aortic bioprosthesis.

Clinical experience with the Hancock porcine bioprosthetic heart valve was reviewed in 150 consecutive patients (82 men and 69 women), 13-83 years of age (mean 65 years and 65% older than 60 years), who underwent aortic valve replacement from February 1977 to December 1979. Thirty-eight percent of the patients had associated procedures, including aortocoronary bypass grafting (CABG), valvuloplasty and multiple valve replacement. Overall early mortality was 5% (eight of 150 patients): three of 98 who had isolated aortic valve replacement (AVR), two of 21 who had aortic and mitral valve replacement (AVR/MVR), one of 26 who had AVR/CABG and two four who had AVR/MVR/CABG. In a follow-up period of 6-42 months (mean 26 months), 10 patients have died. Predicted 3-year survival for the study population was 80%. Ninety percent of surviving patients in New York Heart Association functional class I. Incidence of emboli has been 1.5/100 patient-years. Of the five cases of endocarditis, three were fatal and all required reoperation. There have been no primary valve failures. In 43 patients, transvalvular intraoperative peak systolic gradients (left ventricular to aorta) were measured. In those with 19-mm valves (two patients), the gradient was 12.5 +/- 3.5 mm Hg; in those with 21-mm valves (16 patients), it was 10.0 +/- 6.5 mm Hg; in those with 23-mm valves (18 patients), it was 10.8 +/- 5.9 mm Hg; and in those with 25-mm valves (seven patients), it was 9.8 +/- 5.8 mm Hg. Thus, the Hancock modified orifice valve has good hydraulic performance and a low embolic rate without the need for anticoagulation, so it is acceptable for the elderly patient with a small aortic root.

Adolescent↗
PubMed1981

Hemodynamic evaluation of Hancock and Carpentier-Edwards bioprostheses.

The Hancock (H) and Carpentier-Edwards (CE) porcine xenografts are the most commonly used bioprostheses hemodynamic performance of these valves at each valve size was assessed by intraoperative measurement of transvalvular gradients and cardiac outputs in 122 patients undergoing aortic or mitral valve replacement. At comparable cardiac outputs, peak aortic valve gradients (+/- DS) were: 23-mm valve - H (modified orifice) 10.8 +/- 5.9 mm Hg, CE 7.6 +/- 6.2 mm Hg; 25-mm valve - H 11.9 +/- 5.5 mm Hg, CE 8.3 +/- 5.9 mm Hg; 27/29-mm valve - H 11.0 +/- 6.0 mm Hg, CE 6.6 +/- 5.0 mm Hg. Mitral valve gradients were: 29-mm valve - H 3.7 +/- 1.2 mm Hg, CE 2.8 +/- 1.1 mm Hg; 31-mm valve - H 3.5 +/- 1.0 mm Hg, CE 2.6 +/- 0.7 mm Hg, 33/35-mm valve - H 3.2 +/- 1.9 mm Hg. In both the mitral and aortic positions, Carpentier-Edwards porcine bioprostheses had significantly lower (p less than 0.01 and P less than 0.05, respectively) transvalvular gradients than Hancock porcine xenografts.

Aortic Valve↗
PubMed1980

Results of mitral valvuloplasty with a suture plication technique.

Between January, 1975, and October, 1978, a total of 243 patients underwent repair of the mitral valve with a suture plication technique. Mitral valve replacement (MVR) was performed in 36 cases in which significant residual regurgitation was apparent on testing the valve after repair. The hospital mortality rate was 5.7%. Five patients required MVR within 1 month of operation. A total of 190 patients were discharged from hospital with what was considered to be a satisfactorily functioning mitral valve. Excluding patients from overseas, detailed follow-up information is available in 80 cases. Of these 80 patients, 13 have subsequently undergone MVR. Factors favorably affecting survival and durability of repair are degenerative valve disease and age below 55 years. Clinical and echocardiographic assessment indicate that this method of repair initially produces good symptomatic improvement and a normal or nearly normal pattern of left ventricular filling. The good early results are only maintained in patients with degenerative valve disease. We therefore no longer use or recommend this technique for elderly patients with rheumatic valve disease.

Adult↗
PubMed1980

Development of seamless tri-leaflet valves.

In terms of their hydrodynamic characteristics at physiologically-relevant flows, the tri-leaflet valves show remarkable in vitro performance in comparison with similarly sized or even larger prosthetic valves. The ongoing in vivo studies confirmed the importance of adequate fluid mechanical design criteria, surface smoothness and rigorously clean fabrication procedures to minimize thrombo-embolic phenomena in the absence of anticoagulant therapies. Results from ongoing in vitro and in vivo durability studies suggest these are promising prostheses for valve replacement.

Animals↗
PubMed1980

Myocardial protection with hypothermia and potassium cardioplegia during operation for ascending aortic aneurysms.

The operative management of aneurysms of the ascending aorta continues to present a technical challenge to the surgeon, and the results obtained provide a useful clinical assessment of the means of myocardial protection. We present a series of 35 consecutive patients who underwent operations for aneurysms of the ascending aorta during which myocardial protection was achieved with hypothermia and potassium cardioplegia. Twenty-three patients underwent aortic valve replacement and resection and grafting of a chronic ascending aortic aneurysm. Aortic valve replacement and aneurysmorrhaphy of a chronic ascending aneurysm were performed in five patients. Four patients underwent resection and grafting of a chronic ascending aortic aneurysm and three patients resection and grafting of acute aortic aneurysms. Aortic cross-clamp times varied from 48 minutes to 2 hours, 32 minutes, with a mean cross-clamp time of 1 hour, 29 minutes. There was one death in the hospital in this series of 35 patients for a mortality rate of 2.8%. Of the 34 survivors, there has been one late death from recurrent sternal wound infection. This clinical series documents the efficacy and safety of hypothermic potassium cardioplegia for protection of the myocardium during extended periods of ischemia attending operative correction of ascending aortic aneurysms.

Adolescent↗