Steven Griffin

Early neurological complications after coronary artery bypass grafting and valve surgery in octogenarians.

OBJECTIVE To determine the incidence and risk factors for neurological events complicating cardiac surgery, and the implications for operative outcome in octogenarians. METHODS Of 6791 who underwent primary on-pump CABG and/or valve surgery from 1998 through 2006, 383 were aged > or =80 years. Neurological complications, classified as reversible or permanent, were investigated by head CT scan in patients who did not recover soon after an event. RESULTS There were more females (47% vs 26%, p<0.0001) among octogenarians (n=383, median age 82 years) than among younger patients (n=6408, median age 66 years). Controlled heart failure, NYHA class III/IV and chronic obstructive pulmonary disease were more prevalent in octogenarians while preoperative myocardial infarction was predominant in younger patients. Octogenarians were at higher operative risk (median EuroScore 6 vs 2, p<0.0001). Operative procedures differed between octogenarians and younger patients (p<0.0001); respective frequencies were 45% vs 77% for CABG, 26% vs 10% for AVR, and 23% vs 6% for AVR+CABG. Mortality was higher for octogenarians (8.9% vs 2.1, p<0.0001). Early neurological complications observed in 3.9% of the entire study population were mostly reversible (3.2%). Age > or =80 years (odds ratio [OR] 2.82, 95% confidence interval [CI] 1.89-4.21, p<0.0001), prior cerebrovascular disease (OR 2.23, 95% CI 1.56-3.18, p<0.0001), AVR+CABG (OR 2.92, 95% CI 1.60-5.33, p<0.0001) and MVR+CABG (OR 4.77, 95% CI 2.10-10.85, p<0.0001) were predictive of neurological complications. More octogenarians experienced neurological events (p<0.0001): overall 12.8% vs 3.4%, reversible 11.5% vs 2.8%, permanent 1.3% vs 0.6%. Among octogenarians, neurological complication was associated with elevated operative mortality (18% vs 8% for those without neurological complication, p=0.03), and prolonged ventilation, intensive care stay and hospitalisation. Predictors of neurological complications in octogenarians were blood and/or blood product transfusion (OR 3.60, 95% CI 1.56-8.32, p=0.003) and NYHA class III/IV (OR 7.6, 95% CI 1.47-39.70, p=0.02). CONCLUSION Octogenarians undergoing on-pump CABG and/or valve repair/replacement are at higher risk of neurological dysfunction, from which the majority recover fully. The adverse implications for operative mortality and morbidity, however, are profound. Blood product transfusion which has a powerful correlation with neurological complication should be reduced by rigorous haemostasis with parsimonious use of sealants when appropriate.

The impact of the duration of mechanical ventilation on the respiratory outcome in smokers undergoing cardiac surgery

STUDY OBJECTIVE To determine the impact of the duration of mechanical ventilation on the rate of pulmonary complications in smokers undergoing cardiac surgery. METHODS Retrospective analysis of 2163 patients who underwent elective cardiac surgery between September 1993 and August 1999. Based on a 3-month preoperative smoking cessation, patients were classified as smokers, ex-smokers and non-smokers. Their postoperative pulmonary complications were compared and related to the duration of mechanical ventilation. RESULTS Postoperative pulmonary complications were twice as common in smokers (29.5%) as non-smokers (13.6%) and ex-smokers (14.7%). Although smokers required a longer duration of mechanical ventilation, this was not statistically significant. Smokers had a higher rate of increase in postoperative pulmonary complications beyond 6 h of mechanical ventilation (P<0.002). CONCLUSION Prolonged mechanical ventilation in active smokers undergoing cardiac surgery is associated with a significant increase in the respiratory morbidity. Surgical strategies that allow early extubation may improve the respiratory outcome in smokers.

Effect of bitter tastants on human bronchi

To the Editor: We read with interest the report of the effects of bitter tastants on airway smooth muscle by Deshpande et al.1 and the related News and Views article by Sanderson and Madison2. Deshpande et al.1 report a previously undescribed modulator of airway tone with a unique mode of relaxation in airway smooth muscle that may prove to be clinically significant. We attempted to reproduce the data presented using second-order human bronchi obtained from people with lung cancer after surgical resection. We set rings (n = 24 from nine subjects) at a passive tension of 2 g and contracted them with 1 mM methacholine or 1 mM acetylcholine. We did control relaxations using 10 μM isoprenaline (n = 9). In contrast to the report by Deshpande et al.1, isoprenaline induced rapid (7.9 ± 5.9 min) and potent relaxation of bronchi constricted with acetylcholine (145 ± 39% inhibition of maximum, n = 3) and methacholine (103 ± 49% inhibition of maximum, n = 6) (Fig. 1a). Their claim that bitter taste receptor agonists have three times the efficacy of b-agonists1 may result from the poor performance of isoprenaline in their report. Our own experience and that reported in the literature3,4 is that isoprenaline is a potent and highly efficacious bronchodilator of human airway smooth muscle. We repeated the experiments reported by Deshpande et al.1 using three of the bitter tastants as bronchodilators in bronchi constricted with 1 mM methacholine. Saccharin (n = 5) produced no response up to concentrations of 3 mM (Fig. 1b). Quinine (1 mM; n = 5) and 1–3 mM chloroquine (n = 5) induced relaxation of bronchi (Fig. 1b). At these concentrations, we found that the average time for relaxation to baseline was 23 ± 6 min for quinine and 34 ± 16 min for chloroquine (Fig. 1b). After a mean washout time of 37 ± 10 min, the contractile response to methacholine was reduced (15 ± 19% and 27 ± 15% of the rings that were pre-exposed to quinine and chloroquine, respectively (Fig. 1b)). Our inability to reverse the effects of bitter tastants in the human bronchial preparation used in our study stands in contrast to the report by Deshpande et al.1, in which chloroquine mediated-relaxation was fully reversible in mouse tracheal rings. We interpret these findings as showing that, at very high concentrations, bitter tastants may indeed relax smooth muscle; however, our inability to reverse the effect in washout suggests either irreversible inhibition of contraction or cell injury. Some of the differences between our results may be explained by the use of second-order bronchi in our studies as compared with the fourth-order bronchi in the study by Deshpande et al.1. Different pharmacological classes of agonists have differential effects depending on airway diameter5. In asthma, large airways are thought to be the main contributors to airflow obstruction, whereas in chronic obstructive pulmonary disease, smaller airway constriction has a greater role in the pathophysiology. The localization and function of bitter taste receptors within human airways needs clarification if we are to understand the possible roles of TAS2R agonists as bronchodilators.

Early and Late Survival After Surgical Revascularization for Ischemic Ventricular Fibrillation/Tachycardia

BACKGROUND Ischemic ventricular fibrillation/tachycardia (VF/VT) treated by myocardial revascularization, often with an implanted cardioverter defibrillator, prevents sudden cardiac death. Early series have suggested that recurrent VF/VT threatens survival even after treatment. As late outcome is unknown, we sought to determine if the early survival benefit is sustained. METHODS From January 1999 through January 2007, 93 consecutive patients (75 male, 81%) presented with ischemic VF/VT; 21% survived cardiac arrest and underwent coronary artery bypass graft surgery at our institution. We analyzed their early and late survival. RESULTS Median age was 66 years (range, 44 to 88). Clinical presentation included class III/IV angina (46%), controlled heart failure (43%), prior myocardial infarction (68%), left ventricular ejection fraction less than 0.30 (23%) and 0.30 to 0.50 (35%), left main stem disease (24%), and triple-vessel disease (67%). Surgical revascularization, mostly nonelective (urgent 73%, emergency 7%), was combined with aortic valve replacement in 5 patients and left ventricular pseudoaneurysm repair in 3. Ischemic territories and mean number of diseased coronaries (2.6) corresponded to the grafted territories and average number of grafts (2.5). Operative mortality was 6.5% (n = 6, median EuroSCORE [European System for Cardiac Operative Risk Evaluation] predicted mortality 9). Recurrent VF/VT occurred early postoperatively in 21 patients (24%). All patients had electrophysiologic studies postoperatively and 40% received an implanted cardioverter defibrillator. Of 12 late deaths (16%) at follow-up extending to 8 years, 4 (33%) were due to cardiac causes. Five-year survival was 88%, equivalent to that (83% to 85%) reported for patients with sinus rhythm preoperatively. CONCLUSIONS Complete myocardial revascularization for ischemic VF/VT yields excellent early and late results; 5-year survival is comparable to that of patients with preoperative sinus rhythm.

Is post-sternotomy percutaneous dilatational tracheostomy a predictor for sternal wound infections?

OBJECTIVE Early post-sternotomy tracheostomy is not infrequently considered in this era of percutaneous tracheostomy. There is, however, some controversy about its association with sternal wound infections. METHODS Consecutive patients who had percutaneous tracheostomy following median sternotomy for cardiac operation at our institution from March 1998 through January 2007 were studied, and compared to contemporaneous patients. We identified risk factors for tracheostomy, and investigated the association between percutaneous tracheostomy and deep sternal wound infection (mediastinitis) by multivariate analysis. RESULTS Of 7002 patients, 100 (1.4%) had percutaneous tracheostomy. The procedure-specific rates were: 8.6% for aortic surgery, 2.7% for mitral valve repair/replacement (MVR), 1.1% for aortic valve replacement (AVR), and 0.9% for coronary artery bypass grafting (CABG). Tracheostomy patients differed vastly from other patients on account of older age, severe symptoms, preoperative support, lower ejection fraction, more comorbidities, more non-elective and complex operations and higher EuroScore. Risk factors for tracheostomy were New York Heart Association class III/IV (OR 6.01, 95% CI 2.28-16.23, p<0.0001), chronic obstructive pulmonary disease (OR 1.84, 95% CI 1.01-3.37, p=0.05), preoperative renal failure (OR 3.57, 95% CI 1.41-9.01, p=0.007), prior stroke (OR 3.08, 95% CI 1.75-5.42, p<0.0001), ejection fraction<0.30% (OR 2.73, 95% CI 1.23-6.07, p=0.01), and bypass time (OR 1.008, 95% CI 1.004-1.012, p<0.0001). The incidences of deep (9% vs 0.7%, p<0.0001) and superficial sternal infections (31% vs 6.5%, p<0.0001) were significantly higher among tracheostomy patients. Multivariate analysis identified percutaneous tracheostomy as a predictor for deep sternal wound infection (OR 3.22, 95% CI 1.14-9.31, p<0.0001). CONCLUSIONS Tracheostomy, often performed in high-risk patients, may further complicate recovery with sternal wound infections, including mediastinitis, therefore, patients and timing should be carefully selected for post-sternotomy tracheostomy.

Aprotinin in Primary Cardiac Surgery: Operative Outcome of Propensity Score-Matched Study

BACKGROUND Some recent multicenter series have questioned the safety of aprotinin in primary cardiac operations. We report a large, single-center experience with aprotinin therapy in primary cardiac operations and discuss the limitations and potential confounders of current treatment strategies. METHODS We compared myocardial infarction, neurologic events, renal insufficiency, and operative death after first-time coronary or valve procedures, or both, in 3334 patients treated with full-dose aprotinin with 3417 patients not treated with aprotinin who underwent operation between March 1998 and January 2007. Further analysis was performed for 341 propensity score-matched pairs. RESULTS There were substantial differences between the groups. Aprotinin patients were higher risk on account of older age, unstable symptoms, poor ejection fraction, preoperative hemodynamic support, emergency/urgent operations, and combined coronary/valve operations. Postoperative bleeding and blood product transfusion were considerably reduced in aprotinin patients, as was median duration of mechanical ventilation. Aprotinin was neither a predictor of postoperative myocardial infarction, renal insufficiency, neurologic dysfunction, or operative death. Achieving parity between the groups by propensity score matching eliminated the elevated rates of postoperative renal insufficiency, neurologic dysfunction, and operative death observed in aprotinin patients in the unmatched comparison. These adverse outcomes were evenly distributed between matched groups. Conversely, blood transfusion had univariate associations with all adverse outcome measures. CONCLUSIONS Full-dose aprotinin use was not associated with myocardial infarction, neurologic dysfunction, renal insufficiency, or death after coronary or valve operations. We observed less postoperative bleeding and blood product transfusion, and early extubation with the use of aprotinin.

Surgical nurse assistants in cardiac surgery: a UK trainee's perspective.

OBJECTIVE To assess the impact of surgical nurse assistants on surgical training based on a comparative audit of case-mix and outcome of coronary revascularizations assisted by surgical nurse assistants vs. surgical trainees. METHODS Relevant recent articles on Calman reform of specialist training and European working time directive (EWTD) on junior doctor working hours were reviewed for the discussion. For the audit prospectively entered data of elective and expedite first time coronary artery bypass grafting cases from 2000 to 2003 were analysed. Group A (n=233, Consultant+Surgical nurse assistant), group B (n=1067, Consultant+Junior surgical trainee). Chi-square test, t-test and Fishers test were used as appropriate for statistical analysis. RESULTS Comparative preoperative variables were gender (P=0.8), body mass index (P=0.9), smoking (P=0.3), diabetes mellitus (P=0.2), hypertension (P=1), peripheral vascular disease (P=0.5), previous cerebrovascular accident (CVA)/transient ischemic attack (TIA) (P=0.3), renal dysfunction (P=0.4), preoperative rhythm disturbances (P=0.3), previous Q-wave myocardial infarction (MI) (P=0.4), Canadian Cardiovascular Society angina class (P=0.4), New York Heart Association heart failure class (P=0.4) and left ventricular function (P=0.4). Patients in group B were of higher risk due to age (P=0.01), coronary disease severity (P=0.05), left main stem disease (P=0.001), Parsonnet score (P=0.0001) and Euroscore (P=0.005. Regarding the myocardial protection technique, intermittent cross-clamp fibrillation was used more frequently in group A while antegrade-retrograde cold blood cardioplegia and off-pump coronary artery bypass were used more in group B (P=0.0001). The cross-clamp (P=0.0001) and operation time (P=0.0001) were significantly lower in group A despite a comparable mean number of grafts (P=0.2). There was no significant difference in the immediate postoperative outcome ventilation time (P=0.2), intensive care unit stay, postoperative stay (P=0.2), re-exploration for bleeding (P=0.5), inotrope+intra-aortic balloon pump (P=0.2), postoperative MI (P=0.9), postoperative rhythm disturbances (P=0.9), CVA/TIA (P=0.8), renal dysfunction (P=0.6), wound infection (P=0.7), sternal re-wiring (P=0.2), multi-organ failure (P=0.4) or mortality (P=0.1). CONCLUSIONS Surgical nurse assistants can be used effectively in low-risk cases without compromising postoperative results. However, initiatives to tackle the EWTD should be focused on areas that do not compromise the training needs of junior surgical trainees. An intermediate grade between the present senior house officer and registrar grades could be a way forward.

Changing operative characteristics of patients undergoing operations for coronary artery disease: impact on early outcomes.

BACKGROUND Aggressive nonsurgical revascularization results in high-risk patients presenting for operation at a later stage of coronary artery disease (CAD). This study investigated the effect of temporal changes in operative characteristics on outcomes of surgical revascularization. METHODS We compared preoperative, intraoperative, and postoperative variables of 5633 patients who underwent surgical revascularization for CAD between April 1998 and January 2007, divided into early (1998 to 2002, n = 2746) and late (2004 to 2007, n = 2887) eras. End points were major adverse outcomes (postoperative myocardial infarction, stroke, new dialysis) and operative mortality. RESULTS Median age (66 vs 68 years, p < 0.0001), prevalence of left ventricular systolic dysfunction, left main stem disease, prior angioplasty, diabetes mellitus, concomitant valve operation, and aprotinin use increased steadily over time. Severe symptoms, nonelective operations, mean number of grafts, postoperative bleeding, reopening for bleeding, and blood transfusion declined. Major complications were evenly distributed between the eras. Operative mortality for isolated coronary artery bypass grafting did not change (2.0% vs 1.8% p = 0.62) despite increasing operative risk (p < 0.0001); there was a 100% reduction in the absolute risk (110% to 210%) over time. The markers for operative difficulties, such as longer bypass times, were determinants of operative mortality and, in addition to other predictors like age and left ventricular systolic dysfunction, were more prevalent in the late era. CONCLUSIONS Coronary operations are increasingly performed in higher-risk patients; however, surgical revascularization is nearly twice as safe in current practice compared with a decade ago.

To graft or not to graft? Do coronary artery characteristics influence early outcomes of coronary artery bypass surgery? Analysis of coronary anastomoses of 5171 patients

OBJECTIVE Small coronary size and extensive atherosclerosis pose operative challenges during coronary artery bypass grafting. We investigated the influence of coronary characteristics on early operative outcome. METHODS Prospectively collected data for 5171 patients undergoing first-time coronary artery bypass grafting from April 1, 1999, to December 31, 2007, were analyzed. Coronary diameter estimated or probe-gauged intraoperatively was regarded as small if 1.25 mm or less. Coronary atherosclerosis was graded as none/mild or moderate/severe. Their influence on postoperative major adverse cardiac events, myocardial infarction or reintervention for graft failure, post-cardiotomy shock, and operative mortality, was investigated. RESULTS Of 14,019 coronary anastomoses, 4417 coronaries (31.5%) were small and 5895 coronaries (43.4%) had moderate/severe atherosclerosis. All grafted coronaries were small in 1091 patients (21.1%). Left anterior descending, circumflex, and right coronary arteries received grafts in 94.8% of patients (n = 4903), 74.3% of patients (n = 3842), and 72.5% of patients (n = 3751), with corresponding rates of 31.7%, 31.7%, and 32.6% for small-caliber arteries, 44.4%, 33.3%, and 47.2% for moderate/severe atherosclerosis, and 0.6%, 0.5%, and 3.4% for endarterectomy. Postoperative major adverse cardiac events occurred in 236 patients (4.6%). There was no clear evidence that small caliber of half or more distal anastomoses in a patient (odds ratio, 1.36; 95% confidence interval, 0.97-1.94; P = .07) increased the risk of a major adverse cardiac event, but incomplete revascularization (odds ratio, 1.87; 95% confidence interval, 1.03-3.39; P = .04) and moderate/severe atherosclerosis of the left anterior descending artery (odds ratio 1.37; 95% confidence interval, 1.01-1.87; P = .04) did increase the risk. CONCLUSION Grafting small coronaries did not significantly increase the risk of an early postoperative major adverse cardiac event, but incomplete revascularization did increase the risk. Our findings support grafting small coronaries when technically feasible to prevent incomplete revascularization.

Non-infective morbidity in diabetic patients undergoing coronary and heart valve surgery.

OBJECTIVE Studies of postoperative morbidity in diabetics have focussed on infection; however, autonomic and cardiovascular complications of diabetes potentially increase the risk for non-infective morbidity. We sought to investigate major non-infective early postoperative complications in diabetic patients. METHODS We identified diabetics who underwent CABG and/or valve operation from 1998 through 2007, and compared their clinical characteristics and outcome with a contemporaneous cohort of non-diabetic patients. RESULTS The demographic characteristics of 1145 diabetics were similar to 5534 non-diabetic patients (mean age 66+/-9 years vs 66+/-10 years, p=0.45, female 27.5% vs 26.7%, p=0.59, respectively). Class III/IV angina symptoms (43.9% vs 34.9%, p<0.0001), intravenous nitrates therapy (10.4% vs 6.6%, p<0.0001), heart failure (24.8% vs 20.4%, p=0.001), prior myocardial infarction (37% vs 31%, p<0.0001), ejection fraction </=0.50 (34.5% vs 23.0%, p<0.0001), triple vessel disease (66.3% vs 54.8%, p<0.0001), renal insufficiency (3.6% vs 1.5%, p<0.0001) and peripheral vascular disease (16.1% vs 8.7%) were prevalent amongst diabetics. The predominant operation was CABG (diabetic 84.8% vs non-diabetic 73.9%). Low cardiac output (28.3% vs 24.0%, p=0.002), renal dialysis (2.0% vs 0.8%, p<0.0001) and cerebrovascular events (5.1% vs 3.8%, p=0.04) more often complicated recovery of diabetic patients, but operative mortality was similar for both groups. However, postoperative myocardial infarction was less common in diabetics (0.5% vs 1.4%, p=0.02). Diabetes was not a risk factor for the composite endpoint of major non-infective morbidity and operative mortality (OR 1.15, 95% CI 0.97-1.37, p=0.10). Diabetic patients were prone to longer postoperative hospitalisation (9.7+/-10.5 days vs 8.4+/-6.7 days, p<0.0001) and discharge to a convalescence facilities (9.8% vs 6.9%, p<0.0001). CONCLUSIONS Diabetic patients present for surgery with higher prevalence of cardiovascular risk factors and are more likely to develop major non-infective complications, including cardiac, renal and neurological dysfunction, even though diabetes does not directly influence non-infective postoperative morbidity following CABG and/or valve operations.