Pump Time Research Articles

Efficacy of Leukocyte Filters in the Bypass Circuit for Infants Undergoing Cardiac Operations

Background Leukocyte filters have been used in cardiopulmonary bypass circuits to decrease potentially deleterious consequences of white blood cell product release in adults undergoing cardiac operations. Studies in animal models have also demonstrated benefits of white blood cell depletion during cardiopulmonary bypass. We sought to examine the efficacy of a leukocyte filter placed in the bypass circuit of infants undergoing operation for correction of congenital heart disease. Methods We conducted a retrospective study of infants undergoing correction of congenital heart defects (all had left-to-right shunts) between July 1993 and May 1994. Six infants (group I) had a Leukoguard-3 leukocyte filter (Pall Biomedical Products) placed in the arterial limb of the bypass circuit, and 6 infants (group II) had no filter. We analyzed for differences between groups in intraoperative variables (total pump time, aortic cross-clamp time, deep hypothermic cardiac arrest time, and time for rewarming), postoperative clinical variables (fever in the first 24 hours, days of mechanical ventilation, length of intensive care unit stay, and total hospital stay) and laboratory variables (change in white blood cell and platelet counts preoperatively to postoperatively, and arterial oxygen tension/inspired oxygen fraction ratio). Results Comparisons between groups were made using Student's t test or χ2 where appropriate, and results were considered significant at p less than 0.05. No differences between groups were seen in the demographic data or in any of the intraoperative variables. Fever was the only parameter (clinical or laboratory) showing statistical significance between the groups, affecting 1/6 patients in group I and 5/6 patients in group II (χ2 = 5.33; p < 0.05). Conclusions Although these data suggest that the leukocyte filter offers little clinical benefit, a prospective, randomized study should be undertaken to further elucidate the efficacy of leukocyte depletion for infants undergoing cardiopulmonary bypass for correction of congenital heart disease. Leukocyte filters have been used in cardiopulmonary bypass circuits to decrease potentially deleterious consequences of white blood cell product release in adults undergoing cardiac operations. Studies in animal models have also demonstrated benefits of white blood cell depletion during cardiopulmonary bypass. We sought to examine the efficacy of a leukocyte filter placed in the bypass circuit of infants undergoing operation for correction of congenital heart disease. We conducted a retrospective study of infants undergoing correction of congenital heart defects (all had left-to-right shunts) between July 1993 and May 1994. Six infants (group I) had a Leukoguard-3 leukocyte filter (Pall Biomedical Products) placed in the arterial limb of the bypass circuit, and 6 infants (group II) had no filter. We analyzed for differences between groups in intraoperative variables (total pump time, aortic cross-clamp time, deep hypothermic cardiac arrest time, and time for rewarming), postoperative clinical variables (fever in the first 24 hours, days of mechanical ventilation, length of intensive care unit stay, and total hospital stay) and laboratory variables (change in white blood cell and platelet counts preoperatively to postoperatively, and arterial oxygen tension/inspired oxygen fraction ratio). Comparisons between groups were made using Student's t test or χ2 where appropriate, and results were considered significant at p less than 0.05. No differences between groups were seen in the demographic data or in any of the intraoperative variables. Fever was the only parameter (clinical or laboratory) showing statistical significance between the groups, affecting 1/6 patients in group I and 5/6 patients in group II (χ2 = 5.33; p < 0.05). Although these data suggest that the leukocyte filter offers little clinical benefit, a prospective, randomized study should be undertaken to further elucidate the efficacy of leukocyte depletion for infants undergoing cardiopulmonary bypass for correction of congenital heart disease.

Efficacy of leukocyte filters in the bypass circuit for infants undergoing cardiac operations

Leukocyte filters have been used in cardiopulmonary bypass circuits to decrease potentially deleterious consequences of white blood cell product release in adults undergoing cardiac operations. Studies in animal models have also demonstrated benefits of white blood cell depletion during cardiopulmonary bypass. We sought to examine the efficacy of a leukocyte filter placed in the bypass circuit of infants undergoing operation for correction of congenital heart disease. We conducted a retrospective study of infants undergoing correction of congenital heart defects (all had left-to-right shunts) between July 1993 and May 1994. Six infants (group I) had a Leukoguard-3 leukocyte filter (Pall Biomedical Products) placed in the arterial limb of the bypass circuit, and 6 infants (group II) had no filter. We analyzed for differences between groups in intraoperative variables (total pump time, aortic cross-clamp time, deep hypothermic cardiac arrest time, and time for rewarming), postoperative clinical variables (fever in the first 24 hours, days of mechanical ventilation, length of intensive care unit stay, and total hospital stay) and laboratory variables (change in white blood cell and platelet counts preoperatively to postoperatively, and arterial oxygen tension/inspired oxygen fraction ratio). Comparisons between groups were made using Student's t test or chi 2 where appropriate, and results were considered significant at p less than 0.05. No differences between groups were seen in the demographic data or in any of the intraoperative variables. Fever was the only parameter (clinical or laboratory) showing statistical significance between the groups, affecting 1/6 patients in group I and 5/6 patients in group II (chi 2 = 5.33; p < 0.05). Although these data suggest that the leukocyte filter offers little clinical benefit, a prospective, randomized study should be undertaken to further elucidate the efficacy of leukocyte depletion for infants undergoing cardiopulmonary bypass for correction of congenital heart disease.

Colorectal complications following cardiac surgery

This study was undertaken to assess colorectal complications following cardiopulmonary bypass surgery. This is a retrospective review of 5,801 patients who underwent 5,801 cardiopulmonary bypass procedures from 1985 to 1991. Patients were evaluated for type of bypass procedure, postoperative colorectal complications, age, sex, bypass time, aortic cross-clamp time, elective vs. emergency cases, uses of intra-aortic balloon pump, perioperative hypotension, and use of vasopressors. Statistical analysis was performed using chi-squared analysis and Student's t-test. Nineteen of the 5,801 patients developed 19 colorectal complications, a prevalence of 0.3 percent for the initial hospital stay following bypass surgery. Mortality in those with complications was 37 percent (7/19). Of the 19 complications, 9 (47 percent) followed coronary artery bypass grafting, whereas 10 (53 percent) followed valve replacement or combined coronary artery bypass grafting with other cardiac procedures. Five (26 percent) of the complications followed emergency cases, whereas 14 (74 percent) followed elective cases. Average age of those with complications was 69.8 years, compared with 63.2 years for those without complications. Average aortic cross-clamp time for those with complications was 71 +/- 25 minutes; pump time was 106 +/- 34 minutes. That was significantly higher than in those without complications. Nine (47 percent) patients with complications required vasopressors during the perioperative period, whereas eight (42 percent) suffered prolonged hypotension (systolic blood pressure, < 90 mmHg). It appears that increased age, valve replacement, or combined cardiac procedures, emergency procedures, and prolonged aortic cross-clamp and bypass pump times are risk factors for development of colorectal complications. Hypoperfusion, as suggested by prolonged pump times, clamp times, and emergency procedures may be a possible cause for development of colorectal complications.

Comparison of early and late complications in patients undergoing coronary artery bypass graft surgery with and without concomitant placement of an implantable cardioverter defibrillator

Previous studies have reported a significant morbidity and mortality associated with coronary artery bypass graft (CABG) surgery in conjunction with the placement of an implantable cardioverter defibrillator (ICD) with an epicardial lead system. In the absence of a control group, how significantly the component of concomitant placement of the ICD system contributes to these untoward outcomes remains unknown. The purpose of this study was to assess the short- and long-term complications in patients undergoing CABG surgery in conjunction with the placement of an ICD with epicardial leads and to compare these complications with those of patients who had only CABG surgery (control group). The study group (group A) consisted of 56 patients who underwent CABG surgery and placement of an ICD pulse generator with epicardial leads. A control group (group B) consisted of 56 patients who underwent CABG surgery only during the same time period. The two groups were matched for age, sex distribution, left ventricular function, surgical approach, number of bypass grafts per patient, bypass pump time, and length of follow-up period. The early mortality for group A was 7.1% versus 1.8% for group B ( p > 0.05). The incidence of early morbidity (congestive heart failure, infection, supraventricular and ventricular arrhythmias) for groups A and B was similar (26.8% vs 25.0%, p > 0.05). The incidence of late mortality and morbidity (progression of congestive heart failure, recurrence of coronary events, chronic atrial fibrillation) for groups A and group B were 7.7% versus 5.5% ( p > 0.05) and 23.1% versus 21.8% ( p > 0.05), respectively. However, death caused by cardiopulmonary difficulties was more frequent in group A than group B (12.5% vs 1.8%, p < 0.05). With the availability of the nonthoracotomy lead system and the pulse generator capable of delivering biphasic shock waveform, to place such an ICD system at a later time after the CABG surgery appears to be the preferred approach to treat patients who need both surgical coronary revascularization and ICD.

Centrifugal Pumping: The Patient Outcome Benefits Following Coronary Artery Bypass Surgery

The increased use of the centrifugal pump during coronary artery bypass surgery has been based primarily on theoretical data related to patient safety. There is minimal evidence suggesting improved outcome when compared to the traditional roller pump technology. We prospectively randomized 200 patients undergoing elective coronary artery bypass grafting into centrifugal pump (100 patients) and roller pump (100 patients) groups to compare differences in blood product usage, complication rate, length of stay and net hospital financial balance. Moderate hypothermic bypass was employed on all patients. Cardiopulmonary bypass circuits were similar in both groups with the exception of the arterial pump. Both groups were statistically identical in regard to age, sex, surgeon, complications, total pump time, aortic cross clamp time, prebypass hematocrit and platelet count. The twenty-four hour postoperative hematocrits, platelet counts, red blood cell requirements, blood loss and mortality (2%) were identical in both groups. The centrifugal pump patients had less 24 hour weight gain than their peers in the roller pump group (p=0.05) The length of stay and net hospital financial balance were also statistically favored in the centrifugal pump group (p&lt;0.05). These latter findings were significant when studied in all payors and coronary artery bypass diagnostic related group classifications. Although the mechanism for improvement in length of stay and net hospital financial balance cannot fully be explained, the ramifications in an increasingly cost conscious environment are obvious.

1019-24 Atrial Fibrillation is Strongly Associated with Prolonged Hospital Stay After Open Heart Surgery Even After Correcting for Common Predictors of Morbidity

A trial fibrillation (AF) has been shown to be associated with prolonged hospital stay after open heart surgery. It has been difficult to establish whether AF is causally related to prolonged hospitalization or is simply a marker for more complicated patients. We identified 110 patients in sinus rhythm off antiarrhythmic medications prior to open heart surgery who developed at least 6 hours of AF after surgery and compared them to 96 randomly selected controls who did not develop AF. Patients that developed AF had a longer mean hospital stay after open heart surgery than did patients without postoperative AF (11.7 ± 8.l vs. 7.2 ± 4.4 days, p &lt; 0.0001, 95% CI 2.7 – p6.3 days). Only 15 patients (14%) had AF identified as the sole reason for extending their hospitalization at least one full day 12.5 ± 1.6 days per patient). Nevertheless, after controlling for history of congestive heart failure, myocardial infarction, or diabetes, age, ejection fraction, sex, the type of surgery performed, and bypass pump time. AF remained a highly significant (p &lt; 0.0001) predictor of the duration of hospitalization after surgery. The specific treatment of AF alone probably accounts for only a small portion of the prolonged hospitalization associated with new AF after open heart surgery. Despite this finding. the significantly prolonged hospitalizations of patients that develop AF and the powerful predictive value of AF for explaining prolonged hospital stay even after correcting for other clinical variables suggests that AF is not simply a marker for more complicated patients but in a causal manner contributes to prolonged hospitalization. Effective prevention and treatment of AF should significantly shorten the mean duration of hospitalization after open heart surgery.

Suppurative mediastinitis after open-heart surgery: a case-control study covering a seven-year period in Santander, Spain.

Suppurative mediastinitis developed in 34 (0.9%) of 3,645 patients who underwent median sternotomy at the Hospital Marqués de Valdecilla in Santander, Spain, from 1985 through 1991. These cases were analyzed in a case-control study designed to identify risk factors for poststernotomy mediastinitis. The significant risk factors were (1) preoperative factors: heavy cigarette smoking and history of endocarditis; (2) intraoperative factors: emergency surgery, prolonged duration of surgery, prolonged bypass pump time, ventricular failure, and tearing of the aortic or femoral artery; and (3) postoperative factors: reoperation, prolonged mechanical ventilation, prolonged stay in the intensive-care unit, and tracheostomy. All patients had abnormal sternal wounds (i.e., signs of wound infection or serous discharge). Twelve patients were bacteremic. Thirty-eight organisms were recovered from 31 patients with mediastinitis; 23 of the isolates were gram-positive and 15 were gram-negative. The infections were treated with extensive debridement and appropriate antibiotics. Mortality was 35%. Chronic sternal osteomyelitis was documented in two cases.

Risk factors for stroke after cardiac surgery: Buffalo Cardiac-Cerebral Study Group

The purpose of this study was to identify risk factors for stroke in patients undergoing heart surgery. A retrospective chart review of patients who underwent cardiac surgery in three hospitals of the State University of New York at Buffalo system over a 36-month period was completed. Demographics and risk factors were recorded, and stroke and death were determined by chart review. Carotid artery stenosis was determined by duplex examination. Data were analyzed by chi-squared and multiple logistic regression. One thousand one hundred seventy-nine cases were analyzed, with a mortality rate of 2.3%, stroke rate of 1.6%, and combined stroke/death rate of 3.1%. Four variables were found to be associated with an increased risk of stroke: carotid artery stenosis greater than 50%, redo heart surgery, valve surgery, and prior stroke. Five variables were associated with increased mortality rates:; carotid artery stenosis greater than 50%, redo surgery, peripheral vascular disease, longer pump time, and hypercholesterolemia. Carotid artery stenosis greater than 50% was present in 14.7% of cases. Carotid artery stenosis greater than 75% was not itself associated with increased stroke risk. Most strokes occurred more than 24 hours after surgery. Stroke distribution did not correlate with site of carotid artery stenosis greater than 50%. Most neurologic events after heart surgery occur in a subset of patients who can be defined before operation. Whereas carotid artery stenosis greater than 50% is a strong risk factor, the role of prophylactic endarterectomy is unclear. Future studies should focus on this high-risk subgroup. A prospective study of prophylactic carotid endarterectomy in patients undergoing coronary artery bypass grafting is needed.

Theoretical modeling of relaxation oscillations in Er-doped waveguide lasers

An analysis of relaxation oscillations (/spl lambda//sub s//spl sim/1.5 /spl mu/m) in locally Er-doped optically pumped (/spl lambda//sub p//spl sim/1.48 /spl mu/m) waveguide lasers is reported. The theoretical model is based on time dependent rate equations for a quasi-two-level-system and on the equation of continuity for a gain medium. For the first time a numerically reliable simulation of the elementary properties of the laser oscillations was possible: the build-up time and decay of the relaxation oscillations, the time-dependent repetition period, the steady state signal output power and the evolution of the pump power versus time. Mathematically the problem can be characterized as a large boundary value problem, which can approximately be replaced by a stiff initial value problem of ordinary differential equations. In this report, pump- and signal evolution versus time are presented for planar Er-diffused Ti:LiNbO/sub 3/ waveguide lasers. The numerically obtained results show a good quantitatively agreement with experimental investigations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Are patients receiving amiodarone at increased risk for cardiac operations?

Amiodarone therapy has been implicated as a risk factor for cardiothoracic surgical procedures. In patients undergoing map-guided surgical procedures for the treatment of ventricular tachycardia, we compared the perioperative course of those receiving long-term amiodarone therapy (n = 36) versus that in those not receiving the drug (n = 31). The two groups were similar with respect to age, sex, presenting symptoms, functional class, extent of coronary artery disease, presence of a ventricular aneurysm, technique of ventricular tachycardia abration, cross-clamp or pump time, the number of vessels grafted, the operative fluid balance, and a need for intraaortic balloon pump or inotropic agent support. In 5 patients receiving amiodarone, epinephrine was required to maintain a normal systemic vascular resistance and adequate arterial pressure. Postoperatively, 6 patients (17%) on amiodarone therapy suffered acute respiratory failure. In spite of aggressive therapy, 3 of these patients died. Only 1 patient not receiving amiodarone died of a stroke. We conclude that amiodarone therapy in patients undergoing open heart operations is associated with an increased risk of severe pulmonary complications ( p = 0.03 by Fisher's exact test). Amiodarone therapy should be withheld in patients with ventricular tachycardia until they have been assessed as candidates for possible surgical intervention.

Heparin-Protamine Mismatch

To test the effect of a new system designed to reduce heparin-protamine mismatch on bleeding after open heart surgery. Nonrandomized but consecutive retrospective review of patients undergoing open heart surgery during a 9-month period. Multispecialty referral center. A total of 150 patients comparable by age, body surface area, and coagulation status undergoing primary open heart surgery for either coronary bypass or heart valve replacement. In the first 75 patients (group 1), heparin sodium was neutralized with protamine sulfate, using a fixed ratio (1 mg of heparin sodium to 1.3 mg of protamine sulfate). An activated clotting time was used to confirm heparin neutralization. For the subsequent 75 patients (group 2), titration of heparin and protamine from defined lots was accomplished using activated clotting times adjusted and matched to drug lots to minimize biologic variability. Groups 1 and 2 had comparable operations, pump times, and cross-clamp times. Doses of heparin and protamine and their effect on blood product transfusion and postoperative bleeding were evaluated in all patients. The average protamine sulfate dose for group 2 patients (287.56 +/- 8.3 mg) was significantly lower than that for group 1 (346.01 +/- 12.6 mg) (P < .0005). Less protamine was associated with the transfusion of fewer red blood cells (0.92 +/- 0.15 vs 2.57 +/- 0.38 U) (P < .001), platelets (0.72 +/- 0.8 vs 2.96 +/- 0.80 U) (P < .01), and fresh-frozen plasma (0.83 +/- 2.0 vs 2.01 +/- 0.48 U) (P < .03). No patients in group 2 required reexploration for bleeding, compared with eight patients in group 1. A reduction in protamine dose was associated with significant decreases in blood product use and postoperative bleeding. Excess protamine warrants consideration as both an important and a controllable factor in coagulopathy after open heart surgery.

Cardiac operation with associated pulmonary resection

From February 1988 to May 1992, a total of 11 patients aged 52 to 81 years underwent concomitant cardiac operation and pulmonary resection for bronchogenic carcinoma at our institution. All pulmonary lesions were incidental findings on preoperative chest x-ray films. Diagnosis was obtained in six patients before resection. The operation was performed through a midline sternotomy with all patients requiring cardiopulmonary bypass. Pulmonary procedures included two wedge resections, seven lobectomies, and two double lobectomies. Seven patients underwent lobectomy while supported by bypass, with the lungs collapsed, during rewarming. Total bypass time for these patients averaged 143 minutes. Pathologic examination showed all lesions to be non-small-cell malignant tumors; four adenocarcinomas, four squamous cell carcinomas, two bronchoalveolar carcinomas, and one undifferentiated carcinoma. Nine were stage I and two were stage II. One of the wedge resections showed malignant disease involving the surgical margin that later required completion lobectomy. There were no operative deaths and no major postoperative complications. Postoperative hospital stays ranged from 6 to 17 days (mean 10 days) except for one patient who required a prolonged hospitalization because of a complication after thoracentesis on the side opposite the pulmonary resection. Concomitant cardiac operations with lobectomy can be safely performed during cardiopulmonary bypass without significantly prolonging pump time. Our observations suggest that concomitant cardiac surgery with pulmonary resection is a safe and effective technique with minimal morbidity and short hospital stay.

真空排気時間に及ぼすリークガス中の水分の影響

真空排気時間に及ぼすリークガス中の水分の影響

Warm body, cold heart surgery *1Clinical experience in 2817 patients

Systemic hypothermia is used almost universally in cardiac surgery. Since 1987, 2817 patients have had normothermic cardiopulmonary bypass (NCPB, "warm body", bladder temperature 36 degrees C) with cold blood cardioplegic arrest ("cold heart", 8 degrees-14 degrees C) during open heart surgery. No patients were denied this technique regardless of age, condition or severity of surgery. Clinical Characteristics in Patients: Age range: 16-84 years, mean 66; male/female ratio 3:1; pump time (min) 24-183, mean 91; cross-clamp time (min) 15-148, mean 68; types of surgery: coronary artery bypass (n = 2214), valvular (n = 489) and miscellaneous (aneurysms, tumors, arrhythmias, congenital, etc) (n = 114). One thousand and sixty-nine (1069) patients had urgent coronary artery bypass grafting (CABG). The ejection fraction was less than 0.40 in 843 patients (30%). The thirty-day operative mortality for the entire group was 1.7% (48/2817 patients): CABG = 1% (23/2214 patients), valvular = 3% (15/489 patients) and miscellaneous 9% (10/114 patients). Postoperative complications were: perioperative myocardial infarction (34 patients) = 1.2%, postoperative bleeding requiring reexploration (37 patients) = 1.3%, stroke (27 patients) = 1%, and mediastinal infection (21 patients) = 0.7%. During NCPB (WARM) systemic vascular resistance was extremely low, cardiac output was high and it was easier to wean patients from the pump. No intraaortic balloon pump was used during this period. Pulmonary complications and coagulopathy were extremely rare. These results provide reassurance that NCPB (WARM) in combination with cold cardioplegic arrest provides excellent myocardial and total body protection during cardiac surgery and is particularly suitable for high-risk patients.

Arterial Blood Gases after Coronary Artery Bypass Surgery

Coronary artery bypass graft (CABG) surgery adversely affects arterial blood gas (ABG) determinations. The purposes of this study were to assess serial changes in ABGs following bypass surgery and identify factors that may influence these changes. Room air ABGs were obtained preoperatively and on days 1, 2, 4, 6, and 8 postoperatively on 125 patients undergoing bypass surgery. Fifty-five patients (saphenous vein grafting [SVG] group) had only SVG grafting while 70 (internal mammary artery [IMA] group) received one (60 patients) or two (10 patients) IMA grafts in addition to the SVG grafts and were subjected to pleurotomy. The mean preoperative values (+/- SD) were as follows: PaO2, 75.1 +/- 7.7 mm Hg, P(A-a)O2, 20.9 +/- 7.5 mm Hg; PaCO2, 33.6 +/- 4.1 mm Hg; pH, 7.43 +/- 0.04; hemoglobin, 14.8 +/- 1.4 g/dl; and hematocrit, 44.2 +/- 3.9 percent. There was a large decrease in the PaO2 postoperatively. The nadir for the PaO2 (55.7 +/- 6.6 mm Hg) occurred on the second postoperative day. Eight days postoperatively, there were still significant abnormalities; the PaO2 was 65.7 +/- 7.3 mm Hg, the P(A-a)O2 was 33.2 +/- 8.8 mm Hg; the hemoglobin was 10.5 +/- 1.4 g/dl; and the hematocrit was 31.7 +/- 4.0 percent. The decrease in the PaO2 was particularly noteworthy given the large decrease in the hemoglobin and hematocrit. The changes in the PaO2 were not significantly correlated with the age, number of grafts, pump time, length of anesthesia, or endotracheal intubation or smoking history. Immediately postoperatively, changes were similar in both groups (p > 0.05); on the second postoperative day, the PaO2 had decreased 26.9 percent in the SVG group and 25.5 percent in the IMA group. However, the postoperative abnormalities resolved more slowly in the IMA group (p < 0.05). These observations suggest that the additional trauma to the lungs and chest wall in the IMA group (pleurotomy, the placing of pleural drains, etc) will result in a longer recovery time in the IMA group than in SVG group.

Acute mesenteric ischemia after cardiopulmonary bypass

Acute mesenteric ischemia is an uncommon but catastrophic event after cardiopulmonary bypass. From 1980 to 1990, 16,951 cardiac procedures requiring cardiopulmonary bypass were performed at Emory University Hospital in Atlanta, Ga. Eighteen patients (0.1%) had acute mesenteric ischemia that resulted in intestinal infarction. Emergency cardiac surgery had been performed in 16 of the 18 patients, and all 18 patients were vasopressor dependent for hemodynamic support after surgery. Diagnostic difficulties resulted in the diagnosis of intestinal infarction an average of 912 days after cardiopulmonary bypass. Nonocclusive mesenteric arterial ischemia was the determined cause in all cases. Statistically significant risk factors associated with acute mesenteric ischemia after cardiopulmonary bypass surgery included (1) emergency cardiac surgery (p < 0.0001), (2) the use of an intraaortic balloon pump (p < 0.0001), (3) failed angioplasty requiring emergency surgery (p = 0.0074), (4) prolonged pump time (p = 0.0093), and (5) advanced age (p = 0.0016). A high index of suspicion for mesenteric ischemia after cardiopulmonary bypass in patients with identified risk factors may decrease the diagnostic delay and lead to an improvement in the 67% mortality rate seen in this series.

Ten-year experience with mitral valve replacement in the elderly

Limited data are available on mitral valve replacement in the elderly patient. Therefore we report our 10-year experience including predictors of perioperative mortality and subsequent long-term cardiac mortality in elderly patients with mitral valve replacement compared to younger patients. Of the 126 consecutive patients with mitral valve replacement, 26 were older (77 ± 4, group 1) and 100 were younger (62 ± 9, group 2) than 70 years. Bioprostheses were used more frequently in patients in group 1 (65% vs 7%, p < 0.0001). Of the 21 clinical, ECG, hemodynamic, and angiographic variables studied, patients in group 1 had higher pulmonary artery systolic pressure (57 ± 15 vs 48 ± 19, p < 0.05), fascicular block on ECGs (70% vs 33%, p < 0.005), and greater pump time on cardiopulmonary bypass (160 ± 75 vs 120 ± 50 minutes, p < 0.025). A trend toward a higher perioperative mortality rate was also seen in group 1 (27% vs 12%, p = 0.058). Predictors of perioperative mortality by multivariate analysis were the presence of aortic calcification and prolonged pump time on cardiopulmonary bypass in group 1 and coronary artery disease, female sex, elevated mean pulmonary artery pressure, and postoperative complete atrioventricular block in group 2. During a mean 4-year follow-up period, cardiac mortality and total mortality rates were 42% and 54%, respectively, for group 1 compared to 24% and 35%, respectively, for group 2. Predictors of cardiac mortality by multivariate analysis were aortic calcification, pacemaker implantation, elevated mean pulmonary artery pressure, decreased left ventricular ejection fraction, and smaller prosthetic valve size in group 1 and female sex, coronary artery disease, perioperative atrioventricular block, age, and elevated mean pulmonary artery pressure in group 2. Thus elderly patients with mitral valve replacement have higher perioperative mortality and subsequent cardiac mortality than younger patients. Further studies comparing mitral valve replacement with valve repair and valvuloplasty seem indicated.

Coronary sinus cardioplegia: Clinical trial with only retrograde approach

The cases of 100 consecutive patients who underwent coronary artery bypass grafting with coronary sinus (retrograde) cardioplegia (group R) without the antegrade-retrograde approach were reviewed. To evaluate the safety and the efficacy of this technique, another 100 consecutive patients who underwent a similar procedure but with conventional aortic root (antegrade) cardioplegia (group A) were used as a comparison. The two groups were similar with respect to age, male to female ratio, associated medical problems, extent of coronary artery disease, mean preoperative ejection fraction (0.56 ± 0.13 versus 0.53 ± 0.18), pump time (113.1 ± 43 versus 111.7 ± 38 minutes), aortic cross-clamp time (57.4 ± 20 versus 60.8 ± 23 minutes), number of grafts per patient, level of hypothermia, complication rate, rate of postoperative myocardial infarction (4% versus 3%), and mortality rate (2% versus 2%). Hemodynamic measurements were made 6 hours after operation in 59 patients in group R and 47 patients in group A. The cardiac index, left ventricular stroke work index, and right ventricular stroke work index were better in group R but not significantly so ( p > 0.05). However, only 27% of patients in group R required a temporary pacemaker, and only 9% needed inotropic agents after 6 hours of operation in contrast to 51% and 42%, respectively, in group A ( p < 0.05). There were no complications from catheter intubation. In group R, right ventricular wall temperature (11° ± 3.6 °C) was higher than the septal (10.8° ± 3.2°C) and left ventricular wall temperstures (9.1° ± 2.8°C) ( p > 0.05). Cardioplegia delivery through the coronary sinus alone is safe for clinical use. The technique is simple, provides homogeneous myocardial cooling, and could be a better method of achieving cardioplegia in patients undergoing coronary artery bypass grafting.

Ventricular conduction defects and atrial fibrillation after coronary artery bypass grafting. Multivariate analysis of preoperative, intraoperative and postoperative variables

Preoperative, intraoperative and postoperative variables, which might play a role in the development of ventricular conduction defects (VCD) and atrial fibrillation (AF) following coronary artery bypass grafting (CABG), were evaluated in 236 consecutive patients. VCD and AF developed postoperatively in 15.5% of patients: 4.5% had VCD (subgroup A), 11.0% had AF (subgroup B). In 84.5% of patients VCD and AF did not occur (subgroup C). Univariate analysis showed statistically significant differences between subgroups A and C with respect to: left main significant stenoses and number of diseased vessels. Bypass pump time and aortic cross-clamp time were significantly longer in subgroup B. Multivariate analysis showed a significantly greater incidence of left main disease and of right coronary artery occlusion associated with significant stenosis of the proximal left anterior descending artery in subgroup A. In subgroup B, the duration of aortic cross-clamp time was significantly higher. Ischaemic injury, with increasing duration of cardioplegic arrest, seems to play a key role in the development of AF. Nonhomogeneous cardioplegic delivery to critical areas of myocardium, and particularly to the specialized conducting system, may cause VCD after CABG.

Conjugated Estrogens Reduce Endothelial Prostacyclin Production and Fail to Reduce Postbypass Blood Loss

Intravenous conjugated estrogens correct bleeding times and reduce bleeding in uremia, gastrointestinal telangiectasias, and liver disease. One study found a similar benefit in patients undergoing open heart surgery. The mechanism by which conjugated estrogens improve bleeding times is unknown. We report on the effect of estrogens on endothelial prostacyclin production and bleeding in coronary bypass surgery. In a randomized, double-blind trial, 16 male patients undergoing elective coronary artery bypass surgery received four daily infusions of conjugated estrogens (0.6 mg/kg/day) or placebo, preoperatively. Groups were similar with respect to age, preoperative hemostatic profiles, and pump time. Conjugated estrogens significantly reduced greater saphenous vein endothelial prostacyclin production in the estrogen group compared to control subjects. Postoperative blood loss was not reduced, with a trend toward increased blood loss in the treatment group. We have shown that conjugated estrogens reduce endothelial prostacyclin production and fail to reduce blood loss in coronary bypass surgery.