HSOs: Ontario's answer to HMOs?
Explore the source record for details and available documents.
Capitation Fee↗
Biomedical subjects
H E Scully
Publications and source records attributed to H E Scully.
Hormonal and metabolic responses during coronary artery bypass surgery: role of infused glucose.
Anesthesia, surgery, and hypothermia are conventionally considered the major stress factors in the metabolic and hormonal responses to cardiac surgery. We compared these responses in 14 nondiabetics during and for 24 h after coronary artery bypass surgery; 8 received cardioplegic solutions (C+), and 6 did not (C-). The mean intraoperative glucose load in C+ was 106 g compared to 32 g in C-; postoperatively both groups received 50 g. Marked hyperglycemia (31.8 +/- 4.8 mmol/L) occurred during hypothermia in C+, but dropped to 18.9 mmol/L before surgery ended and to 11.2 +/- 1.1 mmol/L by 2 h postop. In contrast, C- showed constant mild hyperglycemia of 8.3-9.8 mmol/L throughout, significantly less than C+ until 1 h postop. Insulin was suppressed by 55% only during hypothermia, peaking with rewarming in C+ at 2,849 +/- 911 vs. 639 +/- 251 pmol/L in C- (P less than 0.05); as with glycemia, values were comparable after 2 h postop. The pancreatic beta-cell thus responded to hyperglycemia during restoration of normothermia, resulting in a rapid decline in glycemia. This occurred despite elevations in antiinsulin factors in both groups; GH was 14 +/- 4 micrograms/L, cortisol was 607 +/- 38.6 nmol/L, norepinephrine was 11.5 +/- 3.7 nmol/L, epinephrine was 13,863 +/- 3,875 pmol/L, and FFA were 0.36 +/- 0.05 g/L. Early postop, a secondary rise in stress hormones occurred in both groups. Maximal cortisol values were at 4 h (1,186 +/- 140 nmol/L) and peaks of norepinephrine (6.50 +/- 1.66 nmol/L), epinephrine (7,969 +/- 3,602 pmol/L), and FFA (0.27 +/- 0.03 g/L) occurred. The only significant glucagon elevation was at 24 h (C+, 464 +/- 53 ng/L; C-, 350 +/- 241 ng/L; P less than 0.02), Thus, 1) many metabolic responses during coronary artery bypass surgery are influenced by the glucose-containing cardioplegic solution; 2) hypothermia suppresses insulin secretion, but it responds thereafter despite marked elevations of catecholamines, and is associated with decreasing glycemia despite elevated antiinsulin factors; 3) a lesser but highly significant stress response corresponds to awakening from anesthesia; and 4) glucagon plays a minor role in intraoperative hyperglycemia; the rise at 24 h is unexplained.
Aged↗
Outlet strut fracture of the Björk-Shiley 60 degrees Convexo-Concave valve: current information and recommendations for patient care.
Mechanical failure of artificial heart valves can be a catastrophic event. The problem of outlet strut fracture of the Björk-Shiley 60 degrees Convexo-Concave tilting disc prosthesis has received much attention in the medical literature and generated both concern and confusion among patients and physicians. Analysis of current data from the manufacturer, as well as a review of the medical literature, suggests that the overall risk of outlet strut fracture is low and that elective explantation of a well functioning Björk-Shiley 60 degrees Convexo-Concave valve prosthesis is not warranted. Diagnostic features of outlet strut fracture can be seen with overpenetrated chest X-ray films so that diagnosis can be established promptly. Early operation to replace the fractured prosthesis is essential for patient survival.
Aortic Valve↗
Clinical performance of Bjork-Shiley mechanical heart valves: a perspective on outlet strut fractures in the 60 degrees and 70 degrees convexo-concave disc models.
The convexo-concave disc model of Bjork-Shiley mechanical heart valve is a significant improvement over the spherical disc model and compares favourably to other valves, including bioprostheses, with respect to hemodynamics, thromboembolism, anticoagulant related hemorrhage and prosthetic endocarditis. A small number of the 60 degrees and 70 degrees welded outlet strut Bjork-Shiley convexo-concave valves are at risk of sudden structural failure. The risk is constant or decreasing with time. Elective explanation is not recommended. The integral outlet monostrut 70 degrees Bjork-Shiley convexo-concave valve demonstrates further improvements in design and durability, and is recommended for use in patients who are appropriate candidates for mechanical cardiac prostheses.
Aortic Valve↗
The determinants of mortality and morbidity after multiple-valve operations.
The factors predictive of hospital mortality and morbidity after contemporary multiple-valve surgical procedures were identified to develop strategies to improve the results of such procedures. Preoperative, intraoperative, and postoperative information was collected prospectively on 90 consecutive patients undergoing surgical procedures between 1982 and 1984. The operative mortality was 5.6%, and the incidence of postoperative low-output syndrome was 16.7%. Multivariate logistic regression analysis identified tricuspid regurgitation (p less than .03, improvement-of-fit chi square) and the aortic valve lesion (p less than .03) as the independent predictors of postoperative complications (mortality or low-output syndrome). Patients with tricuspid regurgitation and right ventricular decompensation and those with aortic stenosis and left ventricular hypertrophy had limited ventricular functional reserve and faced an increased risk. Improved methods of myocardial protection may reduce the risk in these patients.
Adult↗
Increased risk of urgent revascularization.
To determine the risk factors for operative mortality and morbidity, we performed a prospective analysis of 1,980 patients undergoing isolated coronary artery bypass operations between 1982 and 1984. The operative mortality was 3.5%, and the incidence of perioperative myocardial infarction was 8.6% and low output syndrome, 12.0%. Stepwise logistic regression identified sex, preoperative left ventricular ejection fraction, and the urgency of operation as independent risk factors for postoperative mortality. Urgent revascularization was performed in patients with unstable angina refractory to maximal medical therapy. In these patients the operative mortality was 8.5%. Independent risk factors of postoperative morbidity, in addition to sex, ejection fraction, and urgent revascularization, included a previous bypass procedure, age, and New York Heart Association functional class. Unstable angina unresponsive to medical therapy contributed significantly to the operative risk. Interventions to reduce perioperative ischemic injury, such as improved methods of myocardial protection, may improve the results in high-risk patients.
Cardiac Output, Low↗
Can the results of contemporary aortic valve replacement be improved?
Although the results of contemporary aortic valve replacement are excellent, cardiac surgeons must identify the factors that predict postoperative morbidity and mortality to develop alternative strategies for high-risk patients. Two hundred seventy-seven consecutive patients undergoing isolated aortic valve replacement between 1982 and 1984 were evaluated. Thirty-seven clinical and 13 preoperative hemodynamic variables were analyzed by univariate and multivariate statistics to determine the risk factors for postoperative morbidity and mortality. The operative mortality was 3%, the incidence of a postoperative low output syndrome was 12%, and the incidence of a perioperative myocardial infarction was 5%. A multivariate, logistic regression analysis found that age was the only the only independent predictor of mortality. Three factors independently predicted postoperative low output syndrome: age, the presence of coronary artery disease, and the peak systolic gradient in patients with aortic stenosis. Patients with aortic stenosis had a higher incidence of postoperative ventricular dysfunction (17%) than those with mixed valvular disease (9%) or aortic regurgitation (5%). Perioperative myocardial infarction was predicted by the extent of coronary artery disease. The incidence of perioperative myocardial infarction was higher in patients with triple-vessel coronary artery disease (13%) and those with left main stenosis (18%) than in patients with single- or double-vessel disease (4%) or those without coronary artery disease (4%). Because of the higher risk of aortic valve replacement in older patients, the risk-benefit ratio of the operation must be carefully assessed in the elderly. Improved methods of myocardial protection may reduce the risks for patients with aortic stenosis and symptomatic triple-vessel coronary artery disease.
Adult↗
Comparison between antibiotic irrigation and mobilization of pectoral muscle flaps in treatment of deep sternal infections.
Between January of 1978 and December of 1983, 41 patients developed deep sternal infections with mediastinitis after cardiac operations. Between January of 1978 and December of 1981, 19 of these patients were treated with débridement, primary wound closure, and mediastinal antibiotic irrigation (Group I). Between January of 1982 and December of 1983, 22 patients were treated with débridement, open "clean" packing, and delayed wound closure by the technique of pectoral muscle flap mobilization, which preserves the thoracoacromial pedicles and the pectoral humeral attachments (Group II). The purpose of this study was to compare the results of the treatment of deep sternal infections after cardiac operations with these two techniques. The perioperative hemodynamic, operation, functional, and pathological profiles of both groups of patients were the same. The cosmetic and functional results were the same in both groups as were shoulder girdle and torso mobility. We conclude that either technique is equally effective in the management of patients in whom the serious complication of deep sternal infection with mediastinitis develops after cardiac operation, and we now recommend débridement and pectoral muscle flap closure in one stage.
Anti-Bacterial Agents↗
Thrombosis of a prosthetic valve managed by thrombolysis: a case report.
Thrombosis of a prosthetic valve is one of the most serious cardiovascular events. Emergency replacement of the prosthetic valve has been the standard method of management but carries a high operative risk. This paper describes the successful use of streptokinase, given intravenously, to manage a patient with this complication in the acute phase. Eventually, operation was necessary because the presence of residual organized clot was suspected, but the procedure was performed electively 10 days later.
Adult↗
Morbidity and mortality in mitral valve surgery.
To develop strategies for the management of high-risk patients, contemporary risk factors for operative mortality and postoperative ventricular dysfunction were identified in 214 patients undergoing mitral valve surgery in 1982 and 1983. Thirty-eight preoperative and perioperative variables were prospectively collected and analyzed by univariate and multivariate statistics. The overall mortality was 4.6% and the incidence of postoperative low-output syndrome (LOS) was 18.7%. Forty-seven patients with coronary artery disease (CAD) had a higher mortality and incidence of LOS (as evidenced by the need for inotropic drugs or counterpulsation to maintain blood pressure) (those with CAD 15% mortality, 40% LOS; those without CAD 2% mortality, 13% LOS; p less than .05). The presence of unstable angina and ischemic mitral regurgitation further increased the risk. Age was also a predictor of outcome. Patients who died or had LOS were older (those who died, 65 +/- 7 years, those with LOS, 58 +/- 11 years) than patients who survived and did not have postoperative dysfunction (those who survived, 53 +/- 11; those with no LOS, 53 +/- 11; p less than .01). Mitral regurgitation was associated with a higher (p less than .05) mortality and incidence of LOS (mortality 10.5%, LOS 36%; n = 76) than was mitral stenosis (mortality 0%, LOS 4%; n = 74) or mixed lesions (mortality 3%, LOS 15%; n = 64). In patients without CAD, mitral regurgitation remained a significant predictor of mortality and ventricular dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Permanent cardiac pacing after open-heart surgery: acquired heart disease.
Retrospective review of 5,942 patients who underwent open-heart surgery for acquired heart disease revealed that 123 patients (2.1%) required permanent cardiac pacing postoperatively; 4.6% of these underwent predominantly valvular surgery and 0.6% had coronary bypass. The most important factors appeared to be: 1) preoperative evidence of a conduction disorder; 2) advanced patient age; 3) dense calcium in the aortic annulus; 4) valvular surgery and, especially, tricuspid valve surgery; and 5) poor myocardial protection. Postoperative permanent pacing had a considerable impact on patient morbidity from maintenance operations; most complications were lead-related problems.
Adult↗
Limitations of blood conservation.
Blood conservation has been most successful when blood salvage techniques have been combined with postoperative normovolemic hemodilution. The hemodynamic and myocardial metabolic responses to normovolemic hemodilution were assessed in a prospective randomized trial. Twenty-seven patients were randomized to receive either blood and colloid solutions (colloid group, 13 patients) or crystalloid fluids (crystalloid group, 14 patients) following elective coronary revascularization. Although seven patients in the crystalloid group received blood products when the hemoglobin level fell below 7 gm/dl, blood bank requirements were less in the crystalloid group (colloid, 3.6 +/- 1.2 L; crystalloid, 1.5 +/- 1.0 L, p less than 0.01). The crystalloid group received twice as much fluid to maintain normovolemia (left atrial pressure between 8 and 10 mm Hg) in the first 72 hours postoperatively (colloid, 6.5 +/- 1.9 L; crystalloid, 14.5 +/- 3.1 L, p less than 0.01). The infusion of large volumes of crystalloid fluids resulted in a progressive postoperative anemia (hemoglobin: colloid, 12.1 +/- 1.6 gm/dl, crystalloid 8.9 +/- 1.7 gm/dl, p less than 0.01, 20 hours postoperatively). Although the crystalloid-treated patients had peripheral edema, pulmonary edema could not be documented and there was no difference in the physiological shunt fractions between the two groups. Preload (left atrial pressure), afterload (mean arterial pressure), and cardiac index were similar in the two groups. The crystalloid group had a delayed recovery of myocardial oxygen and lactate extraction postoperatively. Volume loading and atrial pacing 3 to 5 hours postoperatively maintained myocardial lactate extraction in the colloid group but decreased myocardial lactate extraction to ischemic levels in the crystalloid group. The use of crystalloid rather than colloid fluids in the early postoperative period conserved blood products but resulted in postoperative anemia and was associated with a delay in myocardial metabolic recovery. Normovolemic hemodilution should be employed with caution in patients who are at risk of perioperative ischemic injury.
Blood Transfusion↗
A comparison of volume loading and atrial pacing following aortocoronary bypass.
Although cold potassium cardioplegia provides adequate myocardial protection, transient hemodynamic and metabolic instability occasionally occurs after uncomplicated coronary bypass surgery. Two methods to increase cardiac output were compared 2 to 6 hours postoperatively in 24 patients recovering from elective coronary bypass operation. Volume loading increased cardiac index (CI) from 2.1 +/- 0.5 to 2.7 +/- 0.6 L/min/m2 by increasing left atrial pressure (LAP) from 8.6 +/- 3.6 to 13.0 +/- 4.1 mm Hg. Atrial pacing at a rate of 112 +/- 8 beats per minute increased CI from 2.4 +/- 0.5 to 2.7 +/- 0.8 L/min/m2 without a change in LAP. Ejection fraction by nuclear angiography did not change, but the calculated left ventricular end-diastolic volume index (stroke index/ejection fraction) increased with volume loading and decreased with atrial pacing--a decrease in diastolic compliance. Myocardial oxygen extraction did not change, but myocardial lactate extraction increased with volume loading and decreased with atrial pacing. Coronary sinus blood flow was measured in 5 patients and increased with both methods studied. Volume loading demonstrated that myocardial performance was normal and myocardial metabolism increased commensurate with the increase in work. Atrial pacing increased CI but resulted in anaerobic metabolism and a decrease in diastolic compliance. Volume loading rather than atrial pacing will improve CI without producing ischemia in the early postoperative period.
Adult↗
Assessment of mitral and tricuspid competence after valvuloplasty.
Explore the source record for details and available documents.
Heart Arrest, Induced↗
Optimal postoperative volume loading.
Intravenous infusions are required to maintain ventricular preload after uneventful coronary bypass operation. During the early postoperative period, when myocardial metabolic recovery is incomplete, volume loading is intended to stabilize ventricular function and metabolism and to prevent progressive ischemic injury. This study attempts to define the optimal preload for both metabolism and performance. Thirty-seven patients recovering from elective coronary bypass operations and cold potassium cardioplegia underwent volume loading with whole plasma. The initial response (VLA) from a low left atrial pressure (LAP = 7.3 +/- 3.3 mm Hg) was compared with the subsequent response (VLB) from a higher filling pressure (LAP = 10.9 +/- 2.7 mm Hg). Both VLA and VLB produced a similar increase in cardiac index, stroke work index, and end-diastolic volume index (EDVI), and a decrease in ejection fraction (measured by nuclear angiography). Myocardial lactate extraction increased with VLA, but myocardial lactate production resulted with VLB. A careful analysis of these volume loading studies suggested that myocardial performance and compliance were not altered in the early postoperative period. The decrease in ejection fraction with volume loading may have resulted from a combination of increased wall tension and decreased inotropic stimulation. After uneventful coronary bypass surgery, an LAP between 5 and 12 mm Hg corresponded to an EDVI between 30 and 80 ml/m2 and produced adequate cardiac index, stroke work index, and lactate extraction. A lower or higher preload did not improve function and resulted in abnormal metabolism.
Coronary Artery Bypass↗
Effects of postoperative hypertension and its treatment.
Hypertension following aorta-coronary bypass operations can contribute to myocardial ischemia. Nitroprusside therapy will reduce afterload, preload, and coronary perfusion pressure. Since both hypertension and its treatment can result in ischemic injury, nitroprusside must be carefully titrated to optimize cardiac function and metabolism. Thirty-one patients undergoing elective coronary bypass grafting were studied during a hypertensive episode (mean arterial pressure [MAP] = 119 +/- 18 mm Hg) and during nitroprusside therapy at an MAP of 97 +/- 11 mm Hg and at an MAP of 80 +/- 11 mm Hg (normotension). Nitroprusside also produced a significant (p less than 0.05) decrease in left atrial pressure (LAP), left ventricular end-diastolic volume index (EDVI) (stroke index divided by ejection fraction by nuclear angiography), stroke index, and stroke work index (SWI). Cardiac lactate extraction (LEx) and the ratio LEx/SWI increased (p less than 0.05) with the initial nitroprusside therapy, but lactate production resulted when the MAP was lowered to 80 mm Hg. Volume loading studies were performed during hypertension in four patients and during nitroprusside therapy in 15 patients. Neither performance nor compliance was significantly altered at an MAP of 97 mm Hg, but compliance decreased at normotension. Both hypertension and its treatment can result in inadequate myocardial metabolism. Nitroprusside should be titrated to maintain MAP between 90 and 100 mm Hg.
Adult↗
Comparison of alternative cardioplegic techniques.
Cold potassium cardioplegia provides adequate protection for coronary bypass operations, but severe coronary stenoses limit cardioplegic delivery to ischemic regions. The traditional technique delivers cardioplegic solution into the aortic root during the performance of distal anastomoses. The proposed alternative technique constructs proximal as well as distal anastomoses during a prolonged cross-clamp period, but permits more uniform cooling. The two techniques were compared in a prospective concurrent trial of 45 patients undergoing elective coronary bypass grafting. The traditional technique was employed in 26 patients (Group A) and the alternative technique in 19 patients (Group B). In both groups, 700 to 1,000 ml of a crystalloid cardioplegic solution was infused into the aortic root after application of the aortic cross-clamp. In Group A (traditional technique), 500 ml was infused into the aortic root after each distal anastomosis. In Group B (alternative technique), cardioplegic solution was administered through the vein graft after each distal anastomosis, and a proximal anastomosis was constructed after distal anastomoses to the most ischemic regions to permit continued cardioplegic delivery to these regions. The cross-clamp period was shorter in Group A than in Group B (44 +/- 15 versus 60 +/- 18 minutes, p less than 0.01), but the mean temperature in the most ischemic region was warmer (Group A, 19 degrees +/- 3 degrees C; Group B, 15 degrees +/- 3 degrees C, p less than 0.05). The postoperative CK-MB was higher in Group A (Group A, 47 +/- 36; Group B, 21 +/- 9 IU/L, p less than 0.01). Cardiac lactate production persisted longer in Group A (Group A, 4 +/- 1; Group B, 1 +/- 1 hours postoperatively, p less than 0.05). Volume loading 4 hours postoperatively produced a similar increase in left atrial pressure and cardiac index in both groups. In response to volume loading, Group A patients produced lactate, but Group B patients extracted lactate (change in cardiac lactate extraction: Group A, -1.7 +/- 2.3; Group B, +2.5 +/- 5.1 mg/dl, p less than 0.05). The construction of proximal as well as distal anastomoses during a prolonged cross-clamp period permits more uniform cooling and immediate reperfusion. This alternative technique resulted in less injury (CK-MB release) and more rapid recovery of myocardial metabolism.
Aged↗