Biomedical subjects

J Ivanov

Publications and source records attributed to J Ivanov.

At least 55 records · Page 3Linked to original sources

PubMed1996

Cost-effective provision of cardiac services in a fixed-dollar environment.

In the Canadian single-payer system, all hospital payments, including payments for cardiac operations, are negotiated with the government annually. Each hospital is required to remain within 50 cases of its negotiated surgical target. Physicians are paid on a capitated basis and are subject to penalties if negotiated targets are exceeded. There is a computerized waiting list for cardiac operation, with patients classified by an urgency rating scale and objectives set for the maximum period for any given urgency category. Experience has shown that many patients are delayed in the queue, waiting longer than expected for surgical procedures. Waiting times are not influenced by age, sex, or reoperative status, but are influenced by factors such as the presence of multiple risk factors, the number of diseased vessels, stability or unstability of angina, left main coronary artery disease, and recent angioplasty. Waiting time has not been shown to affect operative mortality, the incidence of postoperative low-output syndrome, or length of hospital stay. Canada's 30-year experience with the provision of cardiac services under managed care may provide useful information to hospitals and physicians in the United States currently confronting capitation. The following overview focuses on two critical issues: negotiation of costs and management of patient waiting lists.

Canada↗

PubMed1996

Cardiomyocyte transplantation improves heart function.

BACKGROUND: Transplantation of cultured cardiomyocytes into myocardial scar tissue may prevent heart failure. METHODS: Scar tissue was produced in the left ventricular free wall of 15 rats (weight, 450 g) by cryoinjury. Seven animals had operation only and survived for 8 weeks (sham group). Four weeks after cryoinjury, cultured fetal rat cardiomyocytes or culture medium was injected into the scar tissue of transplantation (n = 5) and control (n = 5) animals, respectively. Five other rats were sacrificed for scar assessment. Eight weeks after cryoinjury heart function in the transplantation, control, and sham groups was measured using a Langendorff preparation. Histologic studies were performed to quantify the extent of the scar and the transplanted cells. RESULTS: Four weeks after cryoinjury, 36% +/- 4% (mean +/- 1 standard error) of the left ventricular free wall surface area was scar tissue. At 8 weeks, the scar size had increased (p < 0.01) to 55% +/- 3% in the control group. Although the scar size (43% +/- 2%) in the transplantation group at 8 weeks was not significantly different from that at 4 weeks, it was less (p < 0.05) than that in the control group. Hearts in the sham group had no scar tissue. The transplanted cardiomyocytes had formed cardiac tissue within the myocardial scar. Systolic and developed pressures in the transplantation group hearts were greater (p = 0.0001) than in the control group hearts but less (p < 0.01) than those in the sham group hearts. CONCLUSIONS: The transplanted cardiomyocytes formed cardiac tissue in the myocardial scar, limited scar expansion, and improved heart function compared with findings in the control hearts.

Animals↗

PubMed1996

Antegrade and retrograde cardioplegia: alternate or simultaneous?

UNLABELLED: Neither antegrade nor retrograde cardioplegic protection provides homogeneous distribution, and a combination may be required to avoid anaerobic metabolism and depressed postoperative ventricular function. Tepid cardioplegia (29 degrees C) avoids the delayed recovery of cardiac function and metabolism associated with cold cardioplegia (15 degrees C) and reduces the anaerobic metabolism seen with warm (37 degrees C) cardioplegia. We compared two techniques that combine antegrade and retrograde tepid cardioplegia: alternate and simultaneous. METHODS: Sixty patients undergoing elective isolated coronary artery bypass grafting were randomized to receive near continuous tepid retrograde and either intermittent antegrade cardioplegia (the alternate technique) or antegrade cardioplegia with the solution delivered concurrently through each completed vein graft (the simultaneous technique). RESULTS: Myocardial lactate extraction was greater after crossclamp release following simultaneous than alternate cardioplegia. Postoperative ventricular function was better after alternate than simultaneous cardioplegia. CONCLUSION: Both techniques permitted rapid postoperative recovery of myocardial metabolism and ventricular function. However, simultaneous cardioplegia was simpler and did not require deairing the aortic root between antegrade infusions.

Adult↗

PubMed1996

Risk factors for stroke in patients undergoing coronary artery bypass grafting.

OBJECTIVE: To determine predictors of stroke in patients undergoing first-time coronary bypass grafting, we prospectively collected data on 1631 consecutive patients. METHODS: Patients with a history of stroke and/or central nervous system symptoms (n = 134) and/or carotid bruits (n = 95) underwent carotid Doppler evaluation. Stenosis greater than 70% was considered significant. Patients with symptomatic disease or asymptomatic bilateral disease were referred for combined coronary bypass and carotid endarterectomy (n = 21). Patients with neurologic symptoms after the operation were assessed by a neurologist and underwent a computed tomographic scan. Events were classified as reversible transient ischemic attack, reversible ischemic neurologic deficit, or irreversible stroke. RESULTS: There were 19 strokes (1.2%) and 20 deaths (1.2%) in this series. In patients with carotid screening, risk of stroke increased with severity of carotid disease and ranged from 0% in patients without stenosis, to 3.2% (1/31) in those with greater than 70% stenosis, and to 27.3% (6/22) in those with carotid occlusion. By stepwise logistic regression analysis six variables were identified as risk factors for stroke. The most important predictor was carotid occlusion with or without contralateral stenosis (odds ratio = 28, 95% confidence interval (8,105). In this group, four of five strokes occurred on the occluded side. Other risk factors were presence of ascending aortic disease at the time of surgery (odds ratio = 12.8, confidence interval 3,48), perioperative myocardial infarction (odds ratio = 8.2, confidence interval 2,33), poor left ventricular function (odds ratio = 4.6, confidence interval 1,19), peripheral vascular disease (odds ratio = 3.2, confidence interval 1,9), and age > 60 years (odds ratio = 2.9, confidence interval 0.8,11). CONCLUSION: We conclude that risk factors for perioperative stroke in patients undergoing coronary artery bypass grafting are multiple. Carotid scanning in patients with neurologic symptoms or carotid bruits can identify patients at increased risk. Patients with carotid occlusion are at high risk for stroke on the occluded side.

Adult↗

PubMed1996

Predictors of low cardiac output syndrome after coronary artery bypass.

The purpose of this study was to identify patients at risk for the development of low cardiac output syndrome after coronary artery bypass. Low cardiac output syndrome was defined as the need for postoperative intraaortic balloon pump or inotropic support for longer than 30 minutes in the intensive care unit to maintain the systolic blood pressure greater than 90 mm Hg and the cardiac index greater than 2.2 L/min per square meter. The preoperative patient characteristics that were independent predictors of low cardiac output syndrome were identified among 4558 consecutive patients who underwent isolated coronary artery bypass at The Toronto Hospital between July 1, 1990, and December 31, 1993. The overall prevalence of low cardiac output syndrome was 9.1% (n = 412). The operative mortality rate was higher in patients in whom low cardiac output syndrome developed than in those in whom it did not develop (16.9% versus 0.9%, p < 0.001). Stepwise logistic regression analyses identified nine independent predictors of low output syndrome (percent frequency in parentheses) and calculated the factor-adjusted odds ratios associated with each predictor: (1) left ventricular ejection fraction less than 20% (27%, odds ratio 5.7); (2) repeat operation (25%, odds ratio 4.4); (3) emergency operation (27%, odds ratio 3.7); (4) female gender (16%, odds ratio 2.5); (5) diabetes (13%, odds ratio 1.6); (6) age older than 70 years (13%, odds ratio 1.5); (7) left main coronary artery stenosis (12%, odds ratio 1.4); (8) recent myocardial infarction (16%, odds ratio 1.4); and (9) triple-vessel disease (10%, odds ratio 1.3). Low cardiac output syndrome is a clinical outcome that may result from inadequate myocardial protection or perioperative ischemic injury. Patients at high risk for the development of low cardiac output syndrome should be the focus of trials of new techniques of myocardial protection to resuscitate the ischemic myocardium.

Aged↗

PubMed1995

Tepid antegrade and retrograde cardioplegia.

To determine the optimal temperature for the combination of antegrade and retrograde cardioplegia, 42 patients undergoing coronary artery bypass grafting were randomized to receive cold (9 degrees C; n = 14), tepid (29 degrees C; n = 14), or warm (37 degrees C; n = 14) blood cardioplegia delivered continuously retrograde and intermittently antegrade. Myocardial oxygen utilization, lactate and acid metabolism, and coronary vascular resistance were measured during the operation and cardiac function was assessed postoperatively. Myocardial oxygen consumption, lactate release and acid release were greatest with warm, intermediate with tepid, and least with cold cardioplegia (p = 0.0001). However, washout of lactate and acid at the time of cross-clamp release was reduced (p = 0.022) with tepid or cold compared with warm cardioplegia. Early postoperative left ventricular function was best preserved (p = 0.01) after tepid than after cold or warm combination cardioplegia. These results suggest that tepid combination cardioplegia reduced metabolic demands but permitted immediate recovery of cardiac function. This technique may provide better myocardial protection than cold or warm combination cardioplegia.

Aged↗

PubMed1995

Is body size the cause for poor outcomes of coronary artery bypass operations in women?

Although small body size and coronary artery diameter are recognized as major contributors to the increased risk of coronary artery bypass grafting in women, few studies have established the independent influence of body size and gender on outcome. We studied 7025 consecutive patients (5694 men, 1331 women) undergoing isolated coronary artery bypass grafting between 1990 and 1994. Women were older, had higher preoperative prevalences of urgent operation because of unstable angina, diabetes, peripheral vascular disease, hypertension, and single-vessel coronary artery disease (p < 0.0001), and a lower prevalence of left ventricular ejection fraction 40% or less (p < 0.0001). The prevalences of operative mortality (men, 1.8%; women, 3.5%), low-output syndrome (men, 6.6%; women, 14.8%), and myocardial infarction (men, 2.8%; women, 5.5%) were higher in women (p < 0.0001). Patients were divided into quartiles for body surface area, weight, height, and body mass index. For both men and women, there was no difference in operative mortality between the highest and lowest quartiles of body size. Women, however, had a higher prevalence of operative mortality than men in the lower quartiles of body surface area, height, and weight and in the higher quartiles of body mass index. Among men, the prevalence of low-output syndrome increased (p < 0.0001) with decreasing body surface area, weight, and body mass index, suggesting that body size did influence the prevalence of low-output syndrome. However, women had a higher prevalence of low-output syndrome than men in every category and quartile of body size (p < 0.0001). Multivariable analysis identified gender as a significant determinant of operative mortality (odds ratio 1.83, 95% confidence interval 1.27 to 2.64) and low-output syndrome (odds ratio 2.52, 95% confidence interval 2.05 to 3.11). When multivariable adjustments were made for body size and preoperative risk factors, gender remained a predictor of both operative mortality and low-output syndrome. Multivariable assessment of risk for men and women separately identified that urgent operation was a predictor of operative mortality (odds ratio 2.52, 95% confidence interval 1.32 to 5.61) and low-output syndrome (odds ratio 1.57, 95% confidence interval 1.14 to 2.17) in women but not men. In conclusion, the increased risk of coronary artery bypass grafting in women may be explained in part by dramatic differences in preoperative risk factors between men and women. In both men and women, small body size did not increase the risk of operative mortality, but may have contributed to the risk of low-output syndrome.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗

PubMed1995

Adequate distribution of warm cardioplegic solution.

Seventy-five patients undergoing coronary artery bypass grafting were randomized to receive warm antegrade (N = 25), warm retrograde (N = 25), or a combination of warm antegrade and retrograde (N = 25) delivery of blood cardioplegic solution. Myocardial oxygen utilization, lactate and acid metabolism, and adenine nucleotides and their degradation products were measured during the operation and cardiac function was assessed postoperatively. Warm retrograde delivery of cardioplegic solution increased lactate and acid release during cardioplegia and reperfusion, decreased left ventricular adenosine triphosphate concentrations, and reduced the washout of adenine nucleotide degradation products from both left and right ventricles. Warm antegrade delivery of cardioplegic solution resulted in less lactate and acid release during cardioplegia but more lactate accumulated in the territory of the left anterior descending artery during the crossclamp period. Intermittent antegrade delivery of the cardioplegic solution during combination cardioplegia washed out lactate and acid, which suggested inhomogeneous delivery of the cardioplegic solution during continuous retrograde cardioplegia. Combination cardioplegia best preserved adenosine triphosphate in the left ventricle and resulted in the best postoperative left and right ventricular function. A combination of intermittent antegrade and continuous retrograde delivery of cardioplegic solution provided better myocardial protection than either antegrade or retrograde delivery of cardioplegic solution alone.

Adenine Nucleotides↗

PubMed1995

Risk factors for stroke following coronary bypass surgery.

Improvements in surgical technique and advances in myocardial protection have resulted in low rates of morbidity and mortality despite a greater incidence of high-risk patients. Noncardiac morbidity prolongs hospital stays and increases the costs of cardiac surgery. This study examines the preoperative predictors of stroke following isolated coronary bypass surgery. The clinical records of 3910 consecutive patients who underwent isolated coronary bypass surgery at the University of Toronto were reviewed. Stepwise logistic regression identified six independent predictors of stroke following CABG (percent in parentheses) and calculated factor adjusted odds ratios (OR) for each risk factor. Triple vessel coronary artery disease was the most important predictor (1.9%, OR 5.71), followed by normothermic systemic perfusion (3.8%, OR 4.85), age > 70 years (3.2%, OR 3.88), a previous history of transient ischemic attacks or stroke prior to surgery (6.1%, OR 3.7), peripheral vascular disease (4.7%, OR 2.77), and diabetes mellitus (2.6%, OR 2.01). The mechanism of stroke is likely different between these high-risk groups and strategies to prevent postoperative stroke should focus on the mechanisms responsible in high-risk patients.

Aged↗

PubMed1994

The optimal cardioplegic temperature.

Seventy-two patients undergoing coronary artery bypass grafting were randomized to receive cold (8 degrees C) antegrade or retrograde, tepid (29 degrees C) antegrade or retrograde, or warm (37 degrees C) antegrade or retrograde blood cardioplegia (n = 12 in each group). Myocardial oxygen utilization as well as lactate and acid metabolism were assessed intraoperatively and cardiac function was assessed postoperatively. Myocardial oxygen consumption and anaerobic lactate release were greatest during warm, intermediate during tepid, and least during cold cardioplegic arrest. Myocardial oxygen consumption and lactate release were underestimated during retrograde cardioplegia because of contamination of aortic root samples. Warm retrograde and tepid retrograde cardioplegia resulted in greater lactate and acid washout with reperfusion. Left ventricular stroke work indices were greater after warm antegrade and tepid antegrade cardioplegia than after cold antegrade cardioplegia, and right ventricular stroke work indices were greatest after warm antegrade cardioplegia. Warm antegrade cardioplegia increased aerobic metabolism during and after cardioplegia and preserved left and right ventricular function. Tepid antegrade cardioplegia reduced anaerobic lactate and acid release during arrest and preserved cardiac function.

Adult↗

PubMed1994

Vitamin E for coronary bypass operations. A prospective, double-blind, randomized trial.

BACKGROUND: Free radical lipid peroxidation contributes to the abnormal metabolism and ventricular function frequently seen after cardiac operations. Antioxidants may improve metabolic and functional recovery. METHODS: A prospective, randomized, double-blind clinical trial was conducted to determine the effects of vitamin E (alpha-tocopherol) (n = 14) or a corn oil placebo (n = 14) in patients undergoing elective coronary bypass operations. The RRR-alpha-tocopheryl acetate doubled the alpha-tocopherol levels in the heart. Myocardial metabolism and ventricular function were assessed after the operation. RESULTS: Atrial pacing induced myocardial lactate production in the control patients but lactate consumption in the alpha-tocopherol-treated patients on bypass 25 minutes after crossclamp release. Left ventricular stroke work indices were higher, at similar ventricular volumes, in the alpha-tocopherol-treated group, which indicates improved preload recruitable stroke work, and diastolic compliance was greater 4 hours after the operation. The postoperative creatine kinase cardiac isoenzyme levels were lower in the patients who received alpha-tocopherol. CONCLUSIONS: Pretreatment with alpha-tocopherol sufficient to double the myocardial concentrations had a small but significant metabolic and functional effect after elective coronary bypass operations when compared with placebo. These results do not justify pretreatment of low-risk patients, but they do justify an evaluation in high-risk patients.

Adult↗

PubMed1994

Optimal flow rates for retrograde warm cardioplegia.

Retrograde delivery of warm blood cardioplegia may improve nutrient cardioplegic flow beyond coronary obstructions, but may not adequately perfuse the right ventricle and the posterior left ventricle. To determine the optimal flow rate for warm retrograde cardioplegia, we assessed 62 patients undergoing elective coronary artery bypass in two studies. In the low flow study, administration of 50 ml/min (n = 9), 75 ml/min (n = 11), or 100 ml/min (n = 7) was associated with high lactate production and oxygen extraction during cardioplegic administration. At 50 minutes of cardioplegic arrest, the coronary venous effluent pH was low in all groups. In the high flow study, 30 patients all received flow rates of 100, 200, and 300 ml/min in randomized order during the crossclamp period. In addition, five patients received cardioplegia at a rate of 500 ml/min for the duration of the crossclamp period. Administration of 200 ml/min or higher minimized lactate production and maintained coronary venous pH within the physiologic range, but flows of 300 ml/min or higher did not increase oxygen use or reduce lactate or acid production. Patients in the low flow groups had significantly greater myocardial lactate release during cardioplegic infusion and after removal of the crossclamp than the high flow group. Warm retrograde cardioplegia should be delivered at flow rates of at least 200 ml/min during elective coronary artery bypass operations.

Adult↗

PubMed1993

Which techniques of cardioplegia prevent ischemia?

One hundred seven patients undergoing coronary artery bypass grafting were randomized to receive warm antegrade (n = 21), warm retrograde (n = 22), cold antegrade (n = 20), cold retrograde (n = 22), or intermittent cold antegrade (n = 22) blood cardioplegia. Myocardial oxygen consumption and lactate production, adenine nucleotides, and adenine nucleotide degradation products were measured during the operation, and creatine kinase-MB release was assessed postoperatively. Warm cardioplegia resulted in greater myocardial lactate production than cold cardioplegia (p = 0.048). Retrograde cardioplegia was associated with greater lactate production than antegrade cardioplegia (p = 0.015). Adenosine triphosphate depletion was similar among groups. However, poorly diffusible metabolites of adenosine triphosphate accumulated to the greatest extent in the intermittent cold group. Levels of hypoxanthine were highest after warm retrograde cardioplegia. Operative mortality and morbidity were low and were not different among groups. In summary, none of the five techniques of cardioplegia evaluated in this study was able to completely prevent myocardial ischemia. Anaerobic lactate production was minimized with cold cardioplegia and with antegrade cardioplegic delivery. Hypothermia may have impaired regeneration of adenosine triphosphate, however, particularly in association with inadequate or intermittent cardioplegic flow.

Adenosine Monophosphate↗

PubMed1993

Ventricular function after normothermic versus hypothermic cardioplegia.

Warm cardioplegia produced by essentially continuous infusion has been used as an alternative to traditional cold intermittent infusion techniques during cardiac surgery, but its effects on postoperative left ventricular function have not been defined. We performed a randomized clinical trial to assess the effects of warm and cold blood cardioplegia on load-independent indices of ventricular function. Fifty-three patients were randomized to warm (n = 27) or cold (n = 26) cardioplegia. Myocardial oxygen consumption, lactate production, adenine nucleotides, and adenine nucleotide degradation products were measured during cardioplegia and reperfusion. In 13 patients per group, pressure-volume loops were constructed and ventricular function was assessed 3 hours after the operation. Warm cardioplegia resulted in greater myocardial lactate production but improved recovery of oxygen consumption during reperfusion. Depletion of adenosine triphosphate was similar between groups, but total adenine nucleotides (adenosine triphosphate + adenosine diphosphate + adenosine monophosphate) fell further during warm cardioplegia. Cold cardioplegia was associated with an accumulation of adenosine diphosphate and adenosine monophosphate. Creatine kinase MB isoenzyme release was reduced in the warm group. Three hours after the operation, end-systolic elastance and preload-recruitable stroke work index were increased after warm cardioplegia, and early diastolic relaxation was also increased. Increased systolic function after warm cardioplegia may have been related to improved myocardial protection, elevated arterial lactate concentrations, or increased circulating catecholamine levels. Altered diastolic compliance in the warm group may reflect greater active relaxation during early diastolic filling.

Adenine Nucleotides↗

PubMed1992

Operative risks and long-term results of operation for left ventricular aneurysm.

A review of 336 consecutive patients who underwent repair of left ventricular aneurysm from 1978 to 1989 disclosed that partial resection of the aneurysm and conventional closure of the ventriculotomy was performed in 281 patients, inverted T closure in 17, and endocardial patch in 38. These two latter techniques were developed in an attempt to restore normal left ventricular geometry. The operative mortality was 6.8% (23 patients). A stepwise logistic regression analysis of various preopeative clinical, hemodynamic, and angiographic variables revealed that left ventricular ejection fraction of 0.20 or less, age greater than 60 years, previous myocardial revascularization, lack of angina, and New York Heart Association functional class IV were independent predictors of operative mortality. The technique of repair was not a predictor of outcome, but when patients with poor left ventricular function were analyzed separately, the operative mortality was reduced from 12.5% to 6.5% when newer techniques were employed. Patients were followed up during a mean of 6.3 years. There have been 51 late deaths, 45 cardiac. Cox regression analysis indicated that poor left ventricular function and left main coronary artery stenosis were the only two predictors of late mortality. The actuarial survival at 10 years was 63% +/- 4%. Most patients (88%) are in New York Heart Association class I or II. These data indicate excellent long-term results after repair of left ventricular aneurysm. Newer techniques of repair are valuable in patients with poor left ventricular function.

Actuarial Analysis↗

PubMed1992

Alternative techniques of cardioplegia.

BACKGROUND: Although normothermic cardioplegia has been used with acceptable clinical results, no studies have previously been performed to determine the metabolic consequences of these various techniques of myocardial protection. Therefore, we have performed a randomized clinical trial to assess the effects of three cardioplegic techniques on myocardial metabolic recovery. METHODS AND RESULTS: Seventy-four patients undergoing coronary artery bypass graft surgery were randomized to receive normothermic antegrade blood cardioplegia (n = 25), normothermic retrograde blood cardioplegia (n = 23), or intermittent cold antegrade blood cardioplegia (n = 26). Myocardial oxygen consumption and lactate production, adenine nucleotides, and adenine nucleotide degradation products were measured during the operation, and cardiac creatine kinase isoenzyme (CK-MB) release was assessed after surgery. Warm antegrade cardioplegia maximized myocardial oxygen consumption during cardioplegic delivery. Postoperative CK-MB release was less after warm antegrade cardioplegia, but the difference was not statistically significant. Warm retrograde cardioplegia resulted in the greatest degree of anaerobic lactate production but did not increase morbidity and mortality. Perioperative myocardial infarctions and postoperative low-output syndrome were most common after cold cardioplegia, but this trend was not statistically significant. During warm antegrade cardioplegia, adenosine triphosphate (ATP) was metabolized to diffusible precursors, which were washed out during cardioplegic infusion. Warm retrograde cardioplegia produced a breakdown of ATP to inosine and hypoxanthine, small molecules that accumulated during the cross-clamp period and were not washed out, perhaps because of inadequate perfusion with retrograde delivery. During cold cardioplegia, ATP was dephosphorylated, and adenosine diphosphate, adenosine monophosphate, and adenosine accumulated. These compounds were not regenerated to ATP but were not washed out of myocytes because they are large anionic molecules. CONCLUSIONS: Intermittent cold cardioplegia inhibited mitochondrial function but prevented the degradation of adenine nucleotides. Warm antegrade cardioplegia had the greatest myocardial oxygen consumption, and warm retrograde cardioplegia had the greatest anaerobic lactate production. There were no differences in clinical outcomes between cardioplegic groups.

Adenosine Triphosphate↗

PubMed1992

Coronary artery bypass grafting in patients with poor ventricular function. Cardiovascular Surgeons of the University of Toronto.

Although patients with severe ventricular dysfunction have improved long-term survival times after coronary bypass procedures, operative morbidity and mortality rates remain high. This study was designed to identify the contemporary risk factors for isolated coronary artery bypass grafting in this high-risk subgroup. Between January 1982 and December 1990, a total of 12,471 patients underwent isolated coronary artery bypass grafting. The 9445 patients with preoperative ejection fractions greater than 40% had a lower operative mortality rate (2.3%) than that of the 2539 patients with ejection fractions between 20% and 40% (4.8%) and that of the 487 patients with ejection fractions less than 20% (9.8%; p less than 0.001). However, patients with ejection fractions of less than 20% were demographically distinct from those with higher ejection fractions. This group was older, with fewer women, a higher frequency of left main stenosis, and more frequent requirement of urgent operation for unstable angina. The risk factors for operative death also varied with preoperative ejection fraction. The traditionally accepted risk factors--urgency of operation, left main coronary artery stenosis, reoperation, sex, and age--were predictive of risk of operative death for patients with ejection fractions greater than 40%. The risk of operative death for patients with ejection fractions between 20% and 40% was predicted by urgency of operation, reoperation, sex, myocardial protection, and age. The only predictor of risk of operative death for patients with ejection fractions less than 20% was urgency of operation. Patients undergoing isolated coronary artery bypass grafting who have severe ventricular dysfunction are therefore a highly selected, high-risk subgroup of patients who risk depends on the urgency of operation. Strategies to improve the results in these patients should be focused on patient selection, improvement of myocardial protection, and more aggressive preoperative treatment of myocardial ischemia.

Age Factors↗

PubMed1992

The effect of warm heart surgery on postoperative bleeding.

The effects of normothermic systemic perfusion (35 degrees to 37 degrees C; n = 73) were compared with those of moderately hypothermic systemic perfusion (25 degrees to 29 degrees C; n = 73) with respect to blood loss, transfusion requirements, and platelet levels in 146 patients undergoing isolated, primary coronary artery bypass grafting. In addition, most patients were given an antifibrinolytic medication during operation as follows: tranexamic acid (10 gm intravenously; n = 63), epsilon-aminocaproic acid (15 gm intravenously; n = 63), or no drug as a control. (n = 20). Normothermic patients tended to bleed less at 24 hours (warm, 864 +/- 42 ml and cold, 918 +/- 68 ml), but these differences were not statistically significant. Patients receiving either tranexamic acid or epsilon-aminocaproic acid, regardless of perfusion temperature, bled less after 6, 12, and 24 hours than did cold control patients (p less than 0.05). Warm control patients also bled less than did cold control patients after 6 or 12 hours (p less than 0.05), and neither drug further reduced blood loss in these patients. Circulating platelet levels were better preserved in patients receiving either tranexamic acid or epsilon-aminocaproic acid and in patients with warm perfusion and no drug than in cold control patients. Normothermic systemic perfusion, tranexamic acid, and epsilon-aminocaproic acid each reduced postoperative blood loss and preserved platelets.

Aminocaproic Acid↗