Michael E. Cowen

Off-pump Coronary Artery Bypass (OPCAB) surgery reduces risk-stratified morbidity and mortality: A United Kingdom multi-center comparative analysis of early clinical outcome

Objective—Off-Pump Coronary Artery Bypass (OPCAB) surgery is gaining more popularity worldwide. The aim of this United Kingdom (UK) multi-center study was to assess the early clinical outcome of the OPCAB technique and perform a risk-stratified comparison with the conventional Coronary Artery Bypass Grafting (CABG) using the Cardio-Pulmonary Bypass (CPB) technique. Methods—Data were collected on 5,163 CPB patients from the database of the National Heart and Lung institute, Imperial College, University of London, and on 2,223 OPCAB patients from eight UK cardiac surgical centers, which run established OPCAB surgery programs. All patients had undergone primary isolated CABG for multi-vessel disease through a midline sternotomy approach, between January 1997 and April 2001. Postoperative morbidity and mortality were compared between the CPB and OPCAB patients after adjusting for case-mix. The mortality of the OPCAB patients was also compared, using risk stratification, to the mortality figures reported by the Society of Cardiothoracic Surgeons of Great Britain and Ireland (SCTS) based on 28,018 patients in the national database who were operated on between January 1996 and December 1999. Results—Morbidity and mortality were significantly lower in the OPCAB patients compared with the CPB patients and the UK national database of CABG patients, over the same period of time, after adjusting for case-mix. Conclusion—This study demonstrates that risk stratified morbidity and mortality are significantly lower in OPCAB patients than CPB patients and patients in the UK national database.

Comparison of the immediate postoperative outcome of using the conventional two drains versus a single drain after lobectomy

BACKGROUND We compared the immediate postoperative outcome and cost-effectiveness of using a single chest drain in the midposition to the conventional apical and basal drains after lobectomy. METHODS Of the 120 consecutive patients who underwent thoracotomy and lobectomy for lung cancer at our center between January 2001 and December 2002, 60 had the conventional 28 French apical and basal drains (group A), whereas the remaining 60 had a single 28 French chest drain placed in the midposition before closure (group B). The assessed outcomes included length of stay, amount and duration of drainage, subcutaneous emphysema, postremoval hemothorax and pneumothorax, drain reinsertion, patient controlled analgesia duration, maximum pain scores, and analgesic usage. RESULTS Both groups matched in terms of age (group A vs group B mean, 65 years old vs 66 years old, respectively; p = not significant [NS]) and gender (M:F, 4:1 for group A vs 4:1 for group B). There was no significant difference in the length of stay (mean, 7.7 days for group A vs 7.8 days for group B; p = NS), amount of drainage (mean, 667 mL for group A vs 804 mL for group B; p = NS), duration of drainage (mean, 4 days for group A vs 4.3 days for group B; p = NS), duration of patient controlled analgesia (mean, 3.7 days for group A vs 4.2 days for group B; p = NS) and analgesic combinations used (nonsteroidal antiinflammatory drugs +/- oral opioids +/- paracetamol) between the two groups. There were no clinically significant postdrain removals of hemothorax or pneumothorax in either group. Group A patients had a significantly higher maximum pain score compared with group B patients (mean, 1.4 vs 1.02, respectively; p = 0.02). Cost savings per patient in group B was more than or equal to 55 US dollars, which added up to a total cost savings of approximately more than or equal to 3,300 US dollars. CONCLUSIONS A single chest drain in the midposition is just as effective, significantly less painful, and much more cost effective than the conventional use of two drains after lobectomy.

Validation of four different risk stratification systems in patients undergoing off-pump coronary artery bypass surgery: a UK multicentre analysis of 2223 patients

Background: Various risk stratification systems have been developed in coronary artery bypass graft surgery (CABG), based mainly on patients undergoing procedures with cardiopulmonary bypass. Objective: To assess the validity and applicability of the Parsonnet score, the EuroSCORE, the American College of Cardiology/American Heart Association (ACC/AHA) system, and the UK CABG Bayes model in patients undergoing off-pump coronary artery bypass surgery (OPCAB) in the UK. Methods: Data on 2223 patients who underwent OPCAB in eight cardiac surgical centres were collected. Predicted mortality risk scores were calculated using the four systems and compared with observed mortality. Calibration was assessed by the Hosmer–Lemeshow (HL) test. Discrimination was assessed using the receiver operating characteristic (ROC) curve area. Results: 30 of 2223 patients (1.3%) died in hospital. For the Parsonnet score the HL test was significant (p < 0.001) and the receiver operating characteristic curve (ROC) area was 0.74. For the EuroSCORE the HL test was also significant (p = 0.008) and the ROC area was 0.75. For the ACC/AHA system the HL test was non-significant (p = 0.7) and the ROC area was 0.75. For the UK CABG Bayes model the HL test was also non-significant (p = 0.3) and the ROC area was 0.81. Conclusions: The UK CABG Bayes model is reasonably well calibrated and provides good discrimination when applied to OPCAB patients in the UK. Among the other three systems, the ACC/AHA system is well calibrated but its discrimination power was less than for the UK CABG Bayes model. These data suggest that the UK CABG Bayes model could be an appropriate risk stratification system to use for patients undergoing OPCAB in the UK.

Inflammatory stimuli up-regulate transient receptor potential vanilloid-1 expression in human bronchial fibroblasts.

ABSTRACT Lung fibroblasts are involved in interstitial lung disease, chronic asthma, and chronic obstructive pulmonary disease (COPD). The expanded fibroblast population in airway disease leads to airway remodeling and contributes to the inflammatory process seen in these diseases. The cation channel transient receptor potential vanilloid-1 (TRPV1) is activated by noxious stimuli, including capsaicin, protons, and high temperatures and is thought to have a role in inflammation. Although TRPV1 expression is primarily reported to be neuronal, some extraneuronal expression has been reported. The authors therefore sought to determine whether human primary bronchial fibroblasts (HPBFs) express TRPV1 and whether inflammatory mediators can induce TRPV1 expression. The authors show that fibroblasts are predominantly TRPV1 negative; however, following stimulation with 3 common inflammatory mediators, tumor necrosis factor α (TNF-α), lipopolysaccharide (LPS), and interleukin-1α (IL-1α), TRPV1 mRNA was observed at 24 and 48 hours post treatment with all 3 mediators. Using Western blotting an increase in TRPV1 expression with all 3 inflammatory mediators was detected with significant increases seen at 72 hours post LPS and IL-1α treatment. In stark contrast to the untreated fibroblasts, significant calcium signaling in response to capsaicin and resiniferatoxin in HPBFs treated for 24 and 48 hours with TNF-α, LPS, or IL-1α was also observed. These results indicate that TRPV1 can be expressed on bronchial fibroblasts in situations where an underlying inflammatory stimulus exists, as is the case in airway diseases such as asthma and COPD.

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.

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.

An Unusual Combination of Diaphragmatic Hernias in a Patient Presenting with the Clinical Features of Restrictive Pulmonary Disease: Report of a Case

Abstract The combination of a Morgagni hernia and a paraesophageal hernia in adults is very rarely encountered in clinical practice. In fact, to our knowledge, only three cases of this condition, which is probably a coincidental occurrence, have been reported in the medical literature. We discuss the management of a 74-year-old man found to have combined Morgagni and paraesophageal hernia who presented with clinical features of a restrictive pulmonary disease.

Survival of Cardiorespiratory Arrest After Coronary Artery Bypass Grafting or Aortic Valve Surgery

BACKGROUND Study objectives were to (1) report the clinical profile of and outcome for patients who experience a cardiorespiratory arrest after coronary artery bypass grafting or aortic valve replacement, and (2) identify factors associated with improved probability of survival. METHODS We identified 108 consecutive patients who had cardiorespiratory arrest after coronary artery bypass grafting or aortic valve replacement between April 1999 and June 2008. We studied the characteristics of arrests and survivors, and performed a multivariate logistic analysis to determine features associated with survival to hospital discharge. RESULTS Cardiac arrest (n = 86) was more common than respiratory arrest (n = 13; unknown cause, n = 9). Cardiorespiratory arrest occurred with decreasing frequency from the day of surgery. Ventricular fibrillation or tachycardia was the dominant mechanism of cardiac arrest (70% versus 17% for asystole versus 13% for pulseless electrical activity), and the principal causes were postoperative myocardial infarction (n = 46; 53%) and tamponade or bleeding (n = 21; 24%). Resternotomy was performed in 45 patients (52%), cardiopulmonary bypass reinstituted in 14 (16%), and additional grafts constructed in 5 (6%). The causes of respiratory arrest were mainly pulmonary (n = 8) and neurologic (n = 5). Survival to hospital discharge was better for respiratory arrest (69%) than for cardiac arrest (50%). Older age, ejection fraction less than 0.30, and postoperative myocardial infarction decreased the probability of survival. CONCLUSIONS Ventricular fibrillation or tachycardia was the most common mechanism, and myocardial infarction, the predominant precipitating cause of cardiac arrest after coronary artery bypass grafting or aortic valve replacement. Despite aggressive resuscitation, outcome is poor. Young patients with good left ventricular function had a better probability of survival if they did not suffer a postoperative myocardial infarction.