Eitan Snir

The effect of cardiac angiography timing, contrast media dose, and preoperative renal function on acute renal failure after coronary artery bypass grafting.

OBJECTIVE Our objective was to assess the effect of the timing of cardiac angiography, contrast media dose, and preoperative renal function on the prevalence of acute renal failure after cardiac surgery. METHODS Data on 395 consecutive patients who underwent coronary artery bypass grafting were prospectively collected. Creatinine clearance was estimated by the Cockcroft-Gault equation. Patients were divided into 3 groups according to the time between cardiac angiography and surgery (group A, < or = 1 day; group B, > 1 day and < or = 5 days; group C, > 5 days). Patients who underwent a salvage operation or were receiving dialysis before surgery were excluded. Acute renal failure was defined as 25% decrease from baseline of estimated creatinine clearance and estimated creatinine clearance of 60 mL/min or less on postoperative day 3. Owing to differences in preoperative characteristics between groups, propensity score analysis was used to adjust those differences. RESULTS Acute renal failure developed in 13.6% of patients. Hospital mortality was 3.3% and was higher in patients in whom acute renal failure developed (22%) versus those in whom it did not (0.3%; P < .001). Multivariable analysis identified preoperative estimated creatinine clearance of 60 mL/min or less (odds ratio [OR], 7.1), operation within 24 hours of catheterization (OR = 3.7), use of more than 1.4 mL/kg of contrast media (OR = 3.4), lower hemoglobin level (OR = 1.3), older age (OR = 1.1), and lower weight (OR = 0.95) as independent predictors of postoperative acute renal failure. Analysis of interaction between contrast dose and time of surgery revealed that high contrast dose (>1.4 mL/kg) predicted acute renal failure if surgery was performed up to 5 days after angiography. CONCLUSIONS Whenever possible, coronary bypass grafting should be delayed for at least 5 days in patients who received a high contrast dose, especially if they also have preoperative reduced renal function.

Histologic atrial myolysis is associated with atrial fibrillation after cardiac operation

BACKGROUND Postoperative atrial fibrillation after cardiac operation is common. Despite the identification of risk factors associated with postoperative atrial fibrillation, the pathophysiologic mechanisms remain unclear. Myolysis has been recently described to be associated with maintenance of atrial fibrillation in experimental animals. In this study, we attempted to identify histopathologic changes in atria that might predict the development of postoperative atrial fibrillation, and specifically address its association with myolysis. METHODS Right appendicular atrial tissue was sampled before and after cardiopulmonary bypass from 60 patients in sinus rhythm who underwent elective coronary artery bypass grafting. RESULTS Fifteen patients (25%) developed postoperative atrial fibrillation. Histopathologic abnormalities were found in most patients (52 of 60). However, only myolysis and lipofuscin levels were found to be an independent histologic finding associated with the development of postoperative atrial fibrillation. Electron microscopy showed that myolytic vacuoles were not membrane bound, and were associated with lipofuscin deposits. Neither mitochondrial pathology nor apoptosis was detected in the atria before or after operation. CONCLUSIONS Abnormalities in biopsies before cardiopulmonary bypass can indicate the susceptibility to develop postoperative atrial fibrillation. This implies that the status of the atrium before cardiopulmonary bypass is a major determinant in the development of this common complication.

A one-way valved atrial septal patch: a new surgical technique and its clinical application.

Patients who undergo surgical repair of congenital heart defects, characterized by a hypoplastic right ventricle or high pulmonary vascular resistance, are at high risk for the development of postoperative right heart failure. This risk may discourage the surgical team from carrying out a biventricular or complete repair in such patients. To reduce the risk for right heart failure, we developed a one-way, valved, atrial septal patch to serve as an artificial one-way foramen ovale and tested it in an animal model. By permitting right-to-left shunt, this device decompresses the failing right ventricle and maintains systemic cardiac output. The device has been used in 15 patients divided into three different groups: group 1 (n = 8), patients with a hypoplastic right ventricle and pulmonic stenosis or atresia, seven of whom underwent a biventricular repair; group 2 (n = 5), patients with evidence of pulmonary disease after longstanding left-to-right shunt caused by a correctable atrial or ventricular septal defect, all of whom had a complete repair; group 3, two patients with acute right heart failure in whom the device was used as a last option of treatment to wean them from cardiopulmonary bypass. This article presents our data in regard to the use of the one-way, valved, atrial septal patch and the indications for its clinical use.

Thromboxane Production in Human Lung During Cardiopulmonary Bypass: Beneficial Effect of Aspirin?

BACKGROUND Increased systemic levels of thromboxane (Tx) during cardiopulmonary bypass (CPB) in humans have been reported. It is not known whether this reflects a general systemic response to the surgical procedure or an increased pulmonary production of Tx in response to ischemia and reperfusion. METHODS Thromboxane B2 levels were measured in the right atrium and left atrium of 14 patients undergoing coronary artery bypass grafting for angina. Eight patients (group 1) were without aspirin for at least 15 days before operation, and 6 patients (group 2) were treated with aspirin (100 mg/day) for at least 1 month before operation. Levels of TxB2 were determined by enzyme immunoassay after lipid extraction and separation. RESULTS Thromboxane B2 levels were elevated throughout CPB. In group 1, left atrial TxB2 levels were significantly higher (p < 0.05) than right atrial levels at all study points during CPB. After pulmonary reperfusion, TxB2 levels in both atria increased significantly (p < 0.02) compared with the levels before cross-clamping of the aorta, and there was an increasing gradient between the two atria (p < 0.05). Mean plasma TxB2 levels during CPB in group 2 were significantly reduced (p < 0.0001) in the right atrium (by 73%) and in the left atrium (by 69%) compared with levels in group 1. CONCLUSIONS The rise in TxB2 levels in the left atrium after CPB in humans reflects production of Tx mainly in the lungs, most probably by ischemic pulmonary tissue and intravascular hematologic components. Aspirin markedly reduces Tx production during CPB, and it might play a major role in preventing pulmonary injury after operations with CPB in humans.

Cardiac surgery in patients on chronic hemodialysis: short and long-term survival.

OBJECTIVE Open-heart surgery carries a high risk for hemodialysis patients. This study focuses on the short and long-term outcomes of hemodialysis patients undergoing heart surgery. DESIGN The study was carried out as a retrospective analysis in the Department of Cardiothoracic Surgery in a large university-affiliated hospital. PATIENTS 115 hemodialysis patients underwent cardiac surgery in our department between 1 July 1996 and 31 July 2006. 67.5 % (77 patients) underwent isolated coronary artery bypass grafting (CABG), 13.2 % (15 patients) underwent isolated aortic valve replacement (AVR) and 20.2 % (23 patients) underwent mitral valve surgery or combined valve and coronary artery bypass grafting or multiple valve surgery. METHODS The relationship between several variables (age, sex, hypertension, diabetes, and previous myocardial infarction, type of disease, preoperative ejection fraction, and congestive heart failure) and operative (30 days) mortality and late survival was analyzed. RESULTS The overall 30-day mortality was 18.3 % (21 patients). It was 13 % (10/77 patients) for the isolated CABG group and 13.3 % (2/15) for the isolated AVR group. Patients undergoing combined valve and coronary surgery or multiple valve surgery had a higher perioperative mortality of 39.1 % (9/23) compared to the isolated CABG and isolated AVR patients. Perioperative death was also higher in patients with moderate and severe LV dysfunction, and in patients with diabetes. The duration of dialysis periods was not related to perioperative death. Mean follow-up was 26.4 +/- 29.7 months (0.1 to 104 months). Actuarial survival at 1 year and 5 years was 76 % and 55 % for isolated CABG, 59 % and 21 % for isolated AVR, and 44 % and 33 % for all other cases, respectively (log rank P = 0.001). CONCLUSION Patients on dialysis have a high risk of perioperative mortality and poor long-term survival rates. Mortality is higher and survival is worse after combined CABG and valve-related procedures or multiple valve surgery than after isolated CABG and AVR.

Elevated level of pro-inflammatory eicosanoids and EPC dysfunction in diabetic patients with cardiac ischemia

BACKGROUND Circulating endothelial progenitor cells (EPCs) are recruited from the blood system to sites of ischemia and endothelial damage, where they contribute to the repair and development of blood vessels. Since numerous eicosanoids including leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) have been shown to exert potent pro-inflammatory activities, we examined their levels in chronic diabetic patients with severe cardiac ischemia in conjunction with the level and function of EPCs. RESULTS Lipidomic analysis revealed a diabetes-specific increase (p<0.05) in inflammatory and angiogenic eicosanoids including the 5-lipoxygenase-derived LTB (4.11±1.17 vs. 0.96±0.27 ng/ml), the lipoxygenase/CYP-derived 12-HETE (117.08±35.05 vs. 24.34±10.03 ng/ml), 12-HETrE (17.56±4.43 vs. 4.15±2.07 ng/ml), and the CYP-derived 20-HETE (0.32±0.04 vs. 0.06±0.05 ng/ml) the level of which correlated with BMI (p=0.0027). In contrast, levels of the CYP-derived EETs were not significantly (p=0.36) different between these two groups. EPC levels and their colony-forming units were lower (p<0.05) with a reduced viability in diabetic patients compared with non-diabetics. EPC function (colony-forming units (CFUs) and MTT assay) also negatively correlated with the circulating levels of HgA1C. CONCLUSION This study demonstrates a close association between elevated levels of highly pro-inflammatory eicosonoids, diabetes and EPC dysfunction in patients with cardiac ischemia, indicating that chronic inflammation impact negatively on EPC function and angiogenic capacity in diabetes.

Is gender an independent risk factor for coronary bypass grafting

BACKGROUND Postoperative mortality after coronary artery bypass grafting (CABG) surgery is traditionally considered to be influenced by gender. However, the data are conflicting and it is not clear whether gender is a true independent risk factor for death in this setting. We analyzed our database to determine whether gender is an independent risk factor for death after CABG. PATIENTS AND DESIGN A retrospective analysis of 1 758 isolated first-time coronary artery bypass graft patients treated between 2003 and 2005 was conducted in the Department of Cardiothoracic Surgery of Rabin Medical Center, a major tertiary facility in Israel. RESULTS The female patients had a distinctly different pre- and intraoperative profile compared with the male patients, and significantly higher postoperative mortality (p < 0.05). On a propensity scoring of 359 matched pairs, the risk factors for death were found to be severe left ventricular dysfunction, chronic obstructive pulmonary disease, and use of an intra-aortic balloon pump (p < 0.05). The addition of intraoperative data to the model yielded only cardiopulmonary bypass time and use of an intra-aortic balloon pump as risk factors for death (p < 0.05). Validation with the bootstrap technique revealed that strong predictors of death (> 50 % of the sample) were cardiopulmonary bypass time, use of an intra-aortic balloon pump, and, to a lesser extent, chronic obstructive pulmonary disease. Female gender was not found to be an independent risk factor for death after coronary artery bypass graft. CONCLUSIONS Female gender is apparently not an independent risk factor for coronary artery bypass graft mortality in this patient group.

DEFINITIVE REPAIR OF TETRALOGY OF FALLOT A Review of 104 Cases

Definitive repair of tetralogy of Fallot was performed on 104 children, including 42 younger than 2 years (24 < 1 year and 7 < 6 months). Twenty-two had previous shunt. Transannular patching was required in 60 cases and conduit grafts in two. During 60-day postoperative observation, five patients died. Of the 99 survivors, 93 recovered without complications, three required prolonged mechanical ventilation, two reoperation and one balloon dilatation for residual left pulmonary artery stenosis. Morbidity and mortality were not significantly higher in the patients younger than 12 months, although transannular patching was more common in that age group. Previous shunt operations entailed higher prevalence of distal stenosis and distortion of the pulmonary arteries, which often necessitated surgical repair, and also considerably increased postoperative morbidity and mortality. As the outcome in definitive repair of Fallots tetralogy is favourable, even in patients younger than 12 months, and as preliminary shunt operations are associated with heightened perioperative morbidity and mortality rates in definitive repair, we advocate the definitive operation for all young patients with severe cyanosis or cyanotic spells.

Rupture of Chordae Tendineae Associated Myxoma of the Left Atrium

Mitral insufficiency is unusual in patients with left atrial myxoma. A patient with myxoma of the left atrium presented with acute pulmonary edema due to ruptured chordae tendineae. Both lesions were unequivocally demonstrated by echocardiography, permitting emergency surgical correction to be undertaken without recourse to angiographic studies. Despite the rarity of acute mitral regurgitation due to rupture of chordae tendineae in association with left atrial myxoma, with only one such case previously reported, an etiologic relationship between the two disorders can be postulated. The association between the two thus should not be unexpected.

Monitoring platelet reactivity during prasugrel or ticagrelor washout before urgent coronary artery bypass grafting

Objectives Patients with acute myocardial infarction pretreated with prasugrel or ticagrelor may require urgent coronary artery bypass grafting (CABG). However, prasugrel and ticagrelor withdrawal period is recommended for 5–7 days before planned CABG to enable full platelet recovery. We hypothesized that monitoring sequential platelet reactivity (PR) could identify patients with early platelet recovery who may benefit from earlier surgery before the guideline-recommended 5–7 day delay. Patients and methods We performed preoperative PR assays in 35 patients with acute myocardial infarction who received prasugrel (60%) or ticagrelor (40%) and required an urgent CABG. When platelet inhibition levels were favorable, on the basis of the VerifyNow assay, surgery was endorsed. CABG-related bleeding parameters were collected and compared with two matched control groups composed of patients who received fewer potent antiplatelet regimens. Results On the basis of platelet function monitoring, we identified 21 (56.7%) patients with a relatively earlier platelet recovery who underwent CABG before the end of the conventional washout period (5–7 days). For these patients, the washout periods were shortened to an average time of 2.6±1.0 days for ticagrelor and 3.8±1.5 days for prasugrel. CABG-related bleeding parameters were comparable with the two matched control groups. Conclusion A strategy of performing preoperative PR assays can identify patients who recover platelet function in less than 5–7 days after ticagrelor or prasugrel discontinuation. This strategy may provide the basis for performing urgent CABGs earlier than the currently recommended delay. Future, larger studies are required to establish these preliminary findings.