Prolonged Aortic Cross-clamp Time Research Articles

Pediatric Warm Open Heart Surgery and Prolonged Cross-Clamp Time

The safety of normothermic pediatric cardiac surgery remains controversial. This study evaluated the performance of normothermic cardiopulmonary bypass (CPB) associated with intermittent warm blood cardioplegia during prolonged aortic cross-clamp time (CCT). This retrospective study included 234 consecutive patients weighing less than 10 kg operated under CPB from August 2006 to November 2007. Patients were divided into two groups: group 1 contained 38 patients with CCT exceeding 90 minutes, and group 2 had 196 patients with shorter CCT. Classic factors were used to analyze outcomes, and outcomes were compared with those from the Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery database. Results, expressed as values for group 1 vs those for group 2, were mortality rate, 5.3% vs 2%; length of hospital stay exceeding 21 days, 5% vs 0.5%; delayed chest closure, 21% vs 2.6%; epinephrine infusion, 45% vs 11%; organ failure, 13% vs 2%; reoperation due to bleeding, 3% vs 0.5%; heart block, 3% vs 1%; time to extubation, in hours, 64 +/- 94 vs 19 +/- 48; plasma lactate concentrations after bypass, 2.6 vs 1.9 mmol/L; length of stay in intensive care, in hours, 100 +/- 105 vs 52 +/- 48. Despite expected differences between the two groups, our results were within the range of values described in the literature. This led us to conclude that warm pediatric cardiac surgery with a long CCT is safe. A large, multicenter, randomized prospective study comparing normothermic and hypothermic pediatric cardiac surgery is underway.

Invited commentary

Adverse neurologic outcomes after heart surgery in general, and cardiac transplantation in particular, have serious consequences: an increased risk of mortality and a diminished quality of life among survivors. They also represent a burden on the health-care system, requiring prolonged hospitalizations and additional aftercare, and as a logical consequence, higher costs. Zierer and colleagues [1Zierer A. Melby S.J. Voeller R.K. et al.Significance of neurologic complications in the modern era of cardiac transplantation.Ann Thorac Surg. 2007; 83: 1684-1690Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar] report on a series of 200 consecutive patients who underwent orthotopic cardiac transplantation during a recent 10-year period. Despite the fact that this review was done retrospectively, specific findings were accurate: operative mortality for the entire series was 8% (17 of 200), but 15% (7 of 46) in patients suffering from neurologic complications (p = 0.074). Multivariate analysis emphasized advanced age, preoperative left ventricular assist assist device (LVAD), intraaortic balloon pump (IABP) support requirement, and prolonged cardiopulmonary bypass time as independent predictors of stroke or transient ischemic attack (TIA) for early neurologic complications. Furthermore, preoperative IABP support requirement, and postoperative renal and hepatic failure were identified as independent predictors of early neurologic complications other than stroke or TIA. Astonishingly, 5-year survival was not significantly impaired in those patients with neurologic complications (66.5 vs 78%; p = 0.149) [1Zierer A. Melby S.J. Voeller R.K. et al.Significance of neurologic complications in the modern era of cardiac transplantation.Ann Thorac Surg. 2007; 83: 1684-1690Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar]. Referring to widespread experience and published literature, 23% of all patients suffering from neurologic sequelae seem to reveal a rather high percentage, but this certainly reflects the fact that the cardiac transplant patient population has shifted to high-risk patients. We believe that a significant correlation between cardiopulmonary bypass (CPB) pressures (ie, 50 mm Hg or less) and prolonged aortic cross-clamp times were observed with development of postoperative neurologic symptoms. Unstable hemodynamic situations (both preoperatively and postoperatively) may directly cause cerebral hypoperfusion or modify patients’ cerebral autoregulation to lower pressure to adapt to the progressive systemic hypotension [2Perez-Miralles F. Sanchez-Manso J.C. Almenar-Bonet Incidence of risk factors for neurologic complications after heart transplantation.Transplant Proc. 2005; 37: 4067-4070Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar]. The presence of gaseous or particulate emboli in the CPB circuit may also represent the causes of neurologic problems. Recently a prospective study on patients undergoing cardiac surgery measuring objectively P300 auditory-evoked potentials revealed no difference between those operations whether cardiac chambers were opened or not [3Iskesen I. Yilmaz H. Yildrim F. et al.Opening the cardiac chambers does not make any difference in p300 measurement.Heart Surg Forum. 2006; 9: 770-773Crossref Scopus (4) Google Scholar]. Last, but not least, other authors stated that the number of posttransplant infections was also associated with neurologic complications [2Perez-Miralles F. Sanchez-Manso J.C. Almenar-Bonet Incidence of risk factors for neurologic complications after heart transplantation.Transplant Proc. 2005; 37: 4067-4070Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar]. Hence, according to the significant decrease of cardiac transplantations due to the broad use of long-lasting LVAD systems and cardiac resynchronization therapy (CRT), the term “bridging to transplant” has emerged with a new importance. Some investigators have speculated that there is a strong connection between infection and neurologic thromboembolic events related to devices during mechanical circulatory support. [4Holman W.L. Bourge R.C. Spruell R.D. et al.Ventricular assist devices as a bridge to cardiac transplantation.Ann Surg. 1997; 225: 695-706Crossref PubMed Scopus (26) Google Scholar] As a matter of fact, seizures are a very poor prognostic indicator and are associated with a 100% mortality in this specific patient group [5Thomas C.E. Jichici D. Petrucci R. et al.Neurologic complications of the Novacor left ventricular assist device.Ann Thorac Surg. 2001; 72: 1311-1315Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar]. In contrast, we were hardly able to find any corresponding literature and information about neurologic symptoms and CRT for the present invited commentary. As congenital cardiac procedures are also of main interest, neurologic complications after orthotopic cardiac transplantation in children and adults tend to be very similar in both incidence and type. However, peripheral neuropathies tend to occur more frequently in adults differing in types of complications in the immediate posttransplant period. [6Martin A.B. Bricker J.T. Fishman M. et al.Neurologic complications of heart transplantations in children.J Heart Lung Transplant. 1992; 11: 933-942PubMed Google Scholar] Significance of Neurologic Complications in the Modern Era of Cardiac TransplantationThe Annals of Thoracic SurgeryVol. 83Issue 5PreviewSevere neurologic complications after cardiac transplantation are devastating outcomes of this life-saving procedure. Incidence, risk factors, and morbidity of neurologic events in the modern era of cardiac transplantation are yet to be defined. Full-Text PDF

Univariate risk factors for prolonged mechanical ventilation in patients undergoing prosthetic heart valves replacement surgery

Data from 736 patients undergoing prosthetic heart valve replacement surgery and concomitant surgery (combined surgery) from January 1998 to January 2004 at Union Hospital were retrospectively reviewed. Univariate logistic regression analyses were conducted to identify risk factors For prolonged mechanical ventilation. The results showed that prolonged cardiopulmonary bypass duration, prolonged aortic cross clamp time and low ejection fraction less than 50 percent (50%) were found to be independent predictors for prolonged mechanical ventilation. Meanwhile age, weight, and preoperative hospital stay (days) were not found to be associated with prolonged mechanical ventilation. It was concluded that, for age and weight, this might be due to the lower number of old age patients (70 years and above) included in our study and genetic body structure of majority Chinese population that favor them to be in normal weight, respectively.

Effect of Pexelizumab in Coronary Artery Bypass Graft Surgery With Extended Aortic Cross-Clamp Time

Prolonged cross-clamp time during cardiac surgery increases the risk of postoperative mortality and myocardial injury. This subanalysis from the pexelizumab for reduction of infarction and mortality in coronary artery bypass grafting surgery (PRIMO-CABG) trial, a phase III double-blind, placebo-controlled study of 3,099 patients undergoing on-pump coronary artery bypass graft surgery with or without valve surgery, assessed the impact of pexelizumab, an investigational C5 complement inhibitor, on postoperative outcomes after prolonged aortic cross-clamp time. The composite endpoint of death or myocardial infarction through postoperative day 30 and death alone through days 30, 90, and 180 were examined in subpopulations of patients across different cross-clamp times. After prolonged cross-clamping (> or = 90 minutes), death, or myocardial infarction through day 30 and death through days 30, 90, and 180 were significantly increased in the intent-to-treat population and were even higher in patients with two or more prespecified risk factors, compared with all patients cross-clamped less than 90 minutes. Pexelizumab significantly reduced the incidence of death or myocardial infarction through day 30, and significantly reduced the incidence of mortality through day 180, in patients with two or more risk factors that required prolonged cross-clamp time. Pexelizumab also significantly reduced perioperative myocardial injury in all patients requiring prolonged cross-clamp time. In this retrospective, subgroup analysis, pexelizumab reduced postoperative morbidity and myocardial injury in patients with multiple risk factors who underwent prolonged cross-clamp time during coronary artery bypass surgery. The clinical benefit of pexelizumab may be related to the effect of complement inhibition in the presence of potential ischemic-reperfusion injury associated with prolonged aortic cross-clamp time.

Continuous retrograde blood cardioplegia ensures prolonged aortic cross-clamping time without increasing the operative risk

The aim of this study was to assess whether the continuous retrograde blood cardioplegia ensures prolonged aortic cross-clamping time without increasing the operative risk. From 1996 to 2003, 204 consecutive patients who had cardiac procedure requiring aortic cross-clamping time > or = 150 min, were prospectively included in this study: low risk group (EuroSCORE < or = 2) 50 patients, medium risk group (EuroSCORE 3-5) 68 patients, high risk group (EuroSCORE > or = 6) 86 patients. The myocardial protection associated induction of cardiac arrest by antegrade injection of hyperkalemic warm blood, continuous retrograde intermediate lukewarm (20 degrees C) blood cardioplegia, retrograde warm blood reperfusion and systemic normothermia. The mean aortic clamping time was 187+/-45 min (range 150-436 min). The mean cardiopulmonary bypass time was 245+/-73 min (range 168-653 min). The operative mortality was 8.3% (17 patients). The mean predicted mortality of the population studied (EuroSCORE logistic method) was 8.4%+/-12 (range 0.87%-76.15%) with a 95% confidence interval of 6.7% to 10%. The observed mortality was not different from the predicted mortality. Continuous retrograde intermediate lukewarm blood cardioplegia associated with systemic normothermia allows prolonged aortic clamping time for complex intervention without increase of operative mortality and morbidity.

Risk Factors for Requirement of Permanent Pacemaker Implantation After Aortic Valve Replacement

The aim of this study was to evaluate the frequency of requirement for permanent pacing and related risk factors after aortic valve replacement. Among 465 patients operated between 1994 and 2004, 19(4.1%) patients with a mean age 49.9 +/- 17.2 years required the implantation of a permanent pacemaker. Eleven of them were female (57.9%). The main indication was aortic stenosis (89.5%). Severe annular calcification was documented in 78.9% of them, and the aortic valve was bicuspid in 57.9%. Risk factors for permanent pacing after aortic valve replacement (AVR) identified by univariate analysis were female sex, hypertension, preoperative ejection fraction, aortic stenosis, annular calcification, bicuspid aorta, presence of right bundle branch block (RBBB) or left bundle branch block (LBBB), prolonged aortic cross-clamp and perfusion times, and preoperative use of calcium channel blockers. Multivariate analysis showed that female sex (p = 0.01, OR; 5.21, 95% CI: 1.48-18.34), annular calcification (p < 0.001, OR; 0.05, 95% CI: 0.01-0.24), bicuspid aortic valve (p = 0.02, OR; 0.24, 95% CI: 0.07-0.84), presence of RBBB (p = 0.009, OR; 0.03, 95% CI: 0.003-0.44) or LBBB (p = 0.01, OR; 0.13, 95% CI: 0.02-0.69), hypertension (p = 0.03, OR; 0.22, 95%CI: 0.05-0.89), and total perfusion time (p = 0.002, OR; 1.05, 95% CI: 1.01-1.08) were associated risk factors. Irreversible atrioventricular block requiring a permanent pacemaker implantation is an uncommon complication after AVR. Risk factors are annular calcification, bicuspid aorta, female sex, presence of RBBB or LBBB, prolonged total perfusion time, and hypertension.

Predictors of gastrointestinal complications after conventional and beating heart coronary surgery

Gastrointestinal complications after cardiac surgery remain a significant problem despite improvements in pre-operative, operative and post-operative care. The pathophysiology is uncertain, and their prevention remains suboptimal. This prospective, randomised study was designed to define the role of cardiopulmonary bypass (CPB) and cardioplegic arrest in the pathogenesis of gastrointestinal complications following coronary artery surgery. Three hundred patients were prospectively randomised to (1) on-pump conventional coronary artery surgery [150 patients, 114 men, mean age 64 (45-75 years)] with mild hypothermic (32c) CPB and cardioplegic arrest of the heart or (2) off-pump surgery [150 patients, 113 men, mean age 64 (38-66) years] on the beating heart. The association of perioperative factors with gastrointestinal complications was investigated by univariate analysis. Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of gastrointestinal complications. There were no significant baseline differences between the groups. Eleven patients in the on-pump group and one patient in the off-pump group had post-operative gastrointestinal complications. Univariate analysis showed that CPB inclusive of cardioplegic arrest, left ventricular ejection fraction <50%, emergency surgery, prolonged aortic cross clamp and CPB time, post-operative low cardiac output syndrome, post-operative inotropic requirement, new onset atrial fibrillation (AF), excessive post-operative blood loss and redo thoracotomy <24 hours were predictors of gastrointestinal complications after coronary artery surgery (all p<0.05). However, stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only predictor of post-operative gastrointestinal complications (OR7.4; CI 3.4-17.9). Cardiopulmonary bypass, inclusive of cardioplegic arrest, is the main independent predictor of post-operative gastrointestinal complications in patients undergoing coronary revascularisation.

Predictors of postoperative complications in high-risk octogenarians undergoing cardiac operations

Background. Cardiac operations in octogenarians are currently reserved for selected patients with severe symptoms and low extracardiac comorbidity; early and midterm results are satisfactory. We evaluated the outcome of high-risk octogenarians undergoing cardiac operations and investigated the predictors of postoperative complications. Methods. Between June 1998 and March 2001, 73 consecutive octogenarians (mean age = 83.1 ± 3.0 years) hospitalized and awaiting operation in our Department were analyzed for postoperative complications. We recorded the main risk factors for cardiovascular disease, symptoms of heart failure, previous myocardial infarction, reoperation, left ventricular ejection fraction, use of intraaortic balloon pump, surgical priority, and operative risk. Cerebrovascular disease, peripheral vascular disease, chronic obstructive pulmonary disease, and renal failure were the preoperative extracardiac comorbidities considered. We adopted a multidisciplinary approach to perioperative management. Results. Surgical procedures included coronary artery bypass grafting in 36 patients (49.3%), valve procedures in 20 (27.4%), and combined coronary artery bypass grafting and valve procedures in 17 patients (23.3%). In-hospital death occurred in 6 patients (8.2%). Twenty-one patients (28.8%) had major postoperative complications including renal failure (15.1%), respiratory failure (8.2%), and myocardial infarction (8.2%). The main predictors of postoperative complications were New York Heart Association functional class IV, Canadian Cardiovascular Society angina class 4, and prolonged aortic cross-clamping time. Conclusions. Cardiac operations can achieve satisfactory results even in high-risk octogenarians. Early surgical intervention before severe symptoms appear, and a multidisciplinary approach to perioperative management, may reduce postoperative complications.

Risk factors influencing early and late mortality after total cavopulmonary connection

Among the later modifications of the Fontan type procedure, a significant alteration was introduced by de Leval and associates when they described the total cavopulmonary connection (TCPC). Although current results of TCPC have encouraged us to extend this procedure to high risk patients, risk factors influencing surgical outcome after TCPC have not been evaluated. We review our experiences with TCPC to identify which risk factors may have had a considerable impact on the outcome of patients undergoing TCPC and to clarify selection criteria of high-risk Fontan candidates for TCPC. We retrospectively reviewed the medical and surgical records of all 76 patients who underwent TCPC between July 1988 and August 2000. A cross-sectional review of these patients was undertaken. There were eight early deaths and four late deaths. In a Fisher's exact test, the following variables were associated with an increased early mortality after TCPC: systemic ventricular morphology (right ventricle), ejection fraction of the systemic ventricle less than 60%, and prolonged cardiopulmonary bypass time (240 min or longer). The log-rank test demonstrated that heterotaxy syndrome, moderate to severe atrioventricular valve regurgitation, prolonged cardiopulmonary bypass time (240 min or longer), and prolonged aortic cross clamp time (70 min or longer) were associated with late mortality after TCPC. Six deaths occurred in eight (75%) patients who had six or more risk factors, whereas six deaths (9%) occurred in those who had five or fewer. Patients with complex cardiac anomalies who have six or more risk factors should be excluded from TCPC candidates.

Selective perfusion of segmental arteries in patients undergoing thoracoabdominal aortic surgery

Background. Reattachment of segmental arteries is one method used to prevent paraplegia associated with thoracoabdominal aortic repair. Nevertheless, even when important segmental arteries are reattached, ischemia causing spinal injury may occur during anastomosis. Methods. In 27 patients undergoing thoracoabdominal aortic repair, we attempted to perfuse the segmental arteries to be reattached with catheters connected to the distal bypass circuit. To identify perioperative risk factors for spinal ischemia, we examined changes in spinal somatosensory evoked potentials. Results. A median value of four segmental arteries were perfused in 20 (74%) of the 27 patients. Changes in somatosensory evoked potential indicative of spinal ischemia were observed in 13 patients (48%). The only risk factor associated with changes in evoked potentials revealed by a multivariate analysis was prolonged aortic cross-clamp time (> 120 minutes). Of the 2 patients who suffered paraplegia, one had the longest clamp time and the other showed spinal cord necrosis due to embolic shower. Conclusions. Despite selective perfusion of segmental arteries, spinal ischemia associated with aortic cross-clamping may occur when clamping is prolonged over 120 minutes. Most of the changes appear to be reversible, however.

Recent clinical experience with left heart bypass using a centrifugal pump for repair of traumatic aortic transection.

To analyze the indications, results, and limitations of using left atrial to femoral artery (LA-FA) bypass to provide distal perfusion during repair of traumatic aortic injuries. There is no consensus about the best method for repair of traumatic aortic transection. Distal aortic perfusion with LA-FA bypass and a centrifugal pump has been the authors' preferred technique for injuries to the aortic isthmus and descending thoracic aorta. From 1988 to 1998, the authors operated on 30 patients with traumatic aortic transection using LA-FA bypass. The mean age of the group was 36+/-2 years. The mechanism of injury was from a motor vehicle accident in 97% of the cases. Distal aortic perfusion was maintained at 50 to 75 mm Hg with flow rates of 1.5 and 3 L/min. The mean aortic cross-clamp time was 38+/-2 minutes, and the mean bypass time was 49+/-2 minutes. No complications related to cannulation, arterial thromboembolism, renal failure, mesenteric ischemia, or hepatic insufficiency occurred. There were no cases of postoperative paraplegia and no deaths. Left atrial to femoral artery bypass is a safe, simple, and effective adjunct to the repair of traumatic injuries to the thoracic aorta. Active distal aortic perfusion preserves spinal cord, mesenteric, and renal blood flow and eliminates the potential catastrophic consequence of spinal cord ischemia from an unexpectedly prolonged aortic cross-clamp time.

Aortic Atherosclerosis Predicts Postoperative Renal Dysfunction

Cardiac surgical procedures carry a relatively high risk of acute renal failure. Previously reported associated factors include advanced age, impaired left ventricular (LV) function, active bacterial endocarditis, pre-existing renal dysfunction, prolonged aortic cross-clamp time, and a postoperative low output state. This prospective U.S. study evaluated the importance of …

Risk factors for life-threatening cavopulmonary thrombosis in patients undergoing bidirectional superior cavopulmonary shunt: An exploratory study

We have observed six patients with life-threatening superior vena caval or pulmonary thrombosis after bidirectional superior cavopulmonary shunt. With the use of a case control study we sought to identify perioperative risk factors for this thrombotic complication. Medical records of six patients with cavopulmonary thrombosis and those of 24 patients in a control group were reviewed to abstract data for potential risk factors. Contingency tables and univariate logistic regression were used to determine associations between various perioperative parameters and occurrence of cavopulmonary thrombosis. Preoperative variables associated with thrombosis included bilateral superior vena cavae, odds ratio: 23, p = 0.02, increased age at surgery (p = 0.05), and female sex (odds ratio: 7, p = 0.05). The McGoon Ratio (index of relative pulmonary artery branch diameter) was inversely related to thrombosis risk (p = 0.08). Two torr increases in mean right atrial (p = 0.08) or ventricular end-diastolic (p = 0.05) pressures were associated with approximately 70% increases in thrombosis risk. Intraoperative prolongation of aortic cross-clamp time related directly to thrombosis risk (p = 0.06). Postoperative variables associated with thrombosis included increased superior vena caval pressure within 12 hours after surgery (odds ratio > or = 10 for 5 torr increase in pressure, p = 0.02) and poor ventricular function (odds ratio: 9, p = 0.06) We conclude that high risk variables for patients undergoing a cavopulmonary shunt include bilateral superior vena cavae, female sex, increasing age, decreased McGoon Ratio, and elevated right atrial and ventricular end-diastolic pressure (before surgery), patients with prolonged aortic cross-clamp time (during surgery), and patients with elevated superior vena caval pressure and poor ventricular function (after surgery).

Management of asymptomatic mild aortic stenosis during coronary artery operations

Management of asymptomatic mild aortic stenosis at the time of coronary artery bypass grafting (CABG) remains controversial. We have retrospectively analyzed a cohort of patients requiring aortic valve replacement (AVR) subsequent to CABG and compared their operative morbidity and mortality with that of a group receiving CABG and AVR simultaneously at the first operation. Analysis is drawn from 28 patients who required AVR 8 +/- 4 years subsequent to CABG (group A) and 175 patients receiving AVR along with CABG at the primary operation (group B). Groups were similar with respect to age, sex, risk factors for cardiac disease, extent of coronary artery disease, left ventricular function, New York Heart Association class, aortic valve area, number of grafts, and size of prosthesis inserted. Patients having AVR subsequent to CABG had a significantly prolonged aortic cross-clamp time and global myocardial ischemic time and incurred a twofold increase in operative mortality. The actuarial survival at 10 years was not significantly different between cohorts. In the 28 patients in group A, the aortic valve area during the period between operations decreased 0.05 mm2/y. The operative mortality and morbidity of a second operation for AVR is high, but there is no significant difference in survival at 10 years. In at least a portion of patients having mild aortic stenosis at the time of CABG there will be progression of the stenosis necessitating reoperation at a later date.

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.

Operative Risk Assessment in Coronary Artery Bypass Surgery, 1990-1993: Evaluation of Perioperative Variables

Patient characteristics and the results of cardiac surgery change with time. To achieve the best possible treatment a continual analysis of results is necessary. The present study analyzes 1225 consecutive patients undergoing isolated aortocoronary bypass surgery for the four-year period ending September 1993. Average age was 63 years (range 32-86 years), 927 (75.7%) patients were male and 298 (24.3%) were female. Hospital mortality was 2.2% (17/787) for elective surgery, 6.3% (21/336) for urgent surgery, and 9.8% (8/82) for emergency surgery. Intraoperative variables increasing independently operative mortality as evidenced by multivariate analysis were the following: prolonged aortic cross-clamping time (p < 0.0001), absence of cold-blood cardioplegia (p = 0.0012), absence of bilateral use of internal mammary artery (p = 0.0035). Likewise, intraoperative variables influencing major adverse outcome (operative mortality and/or need for intra-aortic balloon pulsation) were the following: prolonged aortic cross-clamping time (p < 0.0001), absence of cold-blood cardioplegia (p = 0.0360). In conclusion, global ischemic time was the dominant variable in predicting operative outcome. Furthermore, a protective effect of cold blood cardioplegia and bilateral internal mammary artery grafting was evidenced.

Prolonged Aortic Cross-Clamping Time and Cardiopulmonary Bypass Time Have a Gradient Effect on Early Mortality in Open-Heart Surgery

In 1031 consecutive patients (839 men, 192 women) who underwent coronary artery bypass surgery at Ullev'al Hospital in the period 1988-1990, the risk of early mortality increased in a dose response pattern from increasing aortic cross-clamping time and increasing cardiopulmonary bypass time.

Transient Atrioventricular Block After Release of Aortic Cross-Clamp

To determine the incidence of atrioventricular (A-V) block, 86 patients, aged 58.9 +/- 10.4 yr, undergoing elective coronary artery bypass grafting (CABG) during aortic cross-clamping (ACC) and cold potassium cardioplegia were investigated. The incidence and duration of complete A-V block after release of the aortic cross-clamp was monitored. Twenty-four percent of the patients developed complete A-V block that required temporary pacing for a mean time of 66 +/- 39 min. The volume of cardioplegia used was not significantly different between the patients who developed A-V block and the patients who had no block. The serum potassium level at the time of release of the aortic cross-clamp was within the normal range in both groups. Six factors were correlated with the development of A-V block: old age, preparation by a combination of beta-adrenergic blockers and calcium channel blockers, preoperative bradycardia, the number of vessels grafted, as well as the duration of ACC. Also, the serum potassium level at the time of release of the aortic cross-clamp was significantly higher in the patients who developed A-V block. The high incidence of A-V block in elderly patients undergoing multiple coronary vessel grafting during a prolonged ACC time suggests that suboptimal myocardial preservation may be the main predisposing factor.

Efflux of adenosine and its catabolites during cold blood cardioplegia

Levels of myocardial high-energy phosphates decrease during cardioplegia for open heart operations, with a subsequent increase in the level of adenosine and its metabolites. It has been demonstrated in experimental models that the effluent concentrations of purines can be used as a measure of the average myocardial energy state. Net adenylate loss and myocardial energy state were evaluated here by determining aorta-coronary sinus differences in levels of adenosine catabolites in 17 patients during cold blood cardioplegia for elective coronary artery bypass grafting. Repeated blood samples were taken before cross-clamping of the aorta, when cardioplegic solute was infused into the aortic root and grafts after five distal anastomoses, and after declamping of the aorta. The aorta-coronary sinus differences in levels of total purines increased 4.7-, 7.5-, 7.1-, 7.8-, and 10.2-fold (from the preclamp level of 1.7 ± 0.7 μmol/L; p < 0.001) for grafts one through five anastomosed at an average of 19, 34, 50, 63, and 76 minutes after the aortic cross-clamp, respectively. Hypoxanthine and xanthine were present in the highest concentrations. Vasodilatory adenosine concentrations of 1 to 2 μmol/L were observed in the coronary sinus while the aorta was cross-clamped. There was a linear positive correlation between the aorta-coronary sinus purine differences and corresponding cross-clamp time (r = 0.62; p < 0.001). The metabolite differences settled at a more negative level after declamping of the aorta than that prevailing before placement of the cross-clamp, suggesting continuous washout of adenosine and its catabolites during the 30-minute postclamp observation period. We conclude that considerable net efflux of purines occurs even during cold blood cardioplegia, the relative changes in effluent concentrations being greatest at the very beginning and toward the end of the cross-clamp time. The net loss of high-energy phosphates may be of some clinical significance in the development of postoperative myocardial stunning, especially with prolonged aortic cross-clamp times. On the other hand, monitoring efflux of adenosine and its catabolites into the coronary sinus during and after aortic cross-clamping could be used for comparing different cardioplegia methods.

Pro: Cerebrospinal fluid drainage prevents paraplegia

ORTALITY RATES for repair of thoracic aortic aneurysms remain approximately 10% and paraplegia rates in survivors are reported to exceed 6..5%.‘J The largest published series of 605 patients reported more than 20% of patients with paraplegia after repair of large aneurysms extending from the left subclavian artery and including the abdominal aorta. These large aneurysms, which carry a particularly high risk of paraplegia, accounted for more than one-fourth of all aneurysms repaired in the series.2 The location and extent of the aneurysm, patient age, and prolonged aortic cross-clamp time have all been correlated with an increased incidence of paraplegia.‘J Spinal cord injuries complicating repair of a descending thoracic aneurysm result in neurologic findings similar to the anterior spinal artery syndrome seen after occlusion of the arteria radicularis magna anterior or artery of Adamkiewicz. Motor function is lost in the lower extremities, while pain, temperature, vibratory, and position senses remain intact. The origin of the artery of Adamkiewicz is variable, occurring only 60% of the time in the expected Tg to T12 region. The origin of the artery can be as high as T3 or as low as L5.3 For this reason, during the repair of any given aneurysm, the surgeon does not know which intercostal arteries to preserve or anastamose to the graft. Until the surgeon knows the blood supply of the spinal cord for each individual patient, no intervention such as cerebrospinal fluid (CSF) drainage will completely prevent paraplegia, but such interventions may help maintain the viability of anterior horn cells of the spinal cord during aortic clamping. If surgical resection of the artery of Adamkiewicz has occurred, paraplegia still may or may not result, depending on the adequacy of collateral blood supply through the anterior spinal arteries. Recent reports of late paraplegia often associated with postoperative hypotension may represent patients in whom the artery of Adamkiewicz has been resected, but intraoperative preventive measures have preserved function during the surgery, only to have spinal cord ischemia occur postoperatively. In addition to CSF drainage, two other interventions that are strongly supported in laboratory models and can be applied with minimal risk will be discussed. These are mild hypothermia and the avoidance of glucose-containing solutions. A short discussion of shunting procedures will be