Hemodynamic differences between the awake and anesthetized conditions in normal calves.

There is insufficient information in the literature about baseline circulatory parameters in normal calves in the anesthetized versus postoperative awake conditions under which a large volume of medical research is conducted. Eleven calves (mean body weight, 78.1 ± 14.3 kg) were implanted with a flow probe and fluid-filled pressure lines to measure cardiac output (CO), aortic (AoP), central venous (CVP), pulmonary arterial (PAP), and left atrial pressures (LAP). Systemic (SVR) and pulmonary vascular resistance (PVR) were also calculated. We obtained the above hemodynamic data (n = 11) and epicardial echocardiography (n = 7) during open-chest surgery under isoflurane anesthesia. After full recovery from surgery, animals were evaluated in the awake condition on postoperative days 6-9 using transthoracic echocardiography (n = 7) and the hemodynamic monitoring lines and probes noted (n = 11). CO, AoP, and PAP levels in the anesthetized condition were significantly lower than in the awake condition. Other hemodynamic parameters (CVP, LAP, SVR, and PVR) were not significantly different. In conclusion, data from this study quantify changes in CO, AoP, and PAP in anesthetized calves that may affect the hemodynamic response to experimental therapeutics such as new cardiac assist devices, prosthetic valves, and surgical interventions. Our study also provides baseline data for the translation of the hemodynamic data obtained in acute in vivo calf studies to that of an awake subject.

Endoscopic versus open radial artery harvesting for coronary artery bypass grafting.

BACKGROUND AND AIM OF THE STUDY: The radial artery has become the artery of choice after both internal thoracic arteries for coronary artery bypass grafting (CABG). This study compares wound healing and arm complications after endoscopic versus open radial artery harvesting. METHODS: From January 2002 to July 2004, 509 patients underwent CABG including a radial artery conduit. Thirty-nine had endoscopic and 470 conventional open radial artery harvesting. A propensity score was used to obtain 1:3 matching of all endoscopic to 117 open-harvesting patients. Postoperative wound healing, local neurologic deficits, wound infection, and pain scores were compared. RESULTS: Wound healing: 34 of 39 endoscopic wounds exhibited a perfect Hollander score versus 339 of 470 open-harvest wounds (p = 0.01). Wound appearance was better for endoscopic harvesting (p = 0.004). Three incomplete neurologic deficits were observed after open harvesting versus one complete neurologic deficit after endoscopic harvesting that recovered prior to hospital discharge. Incidence of wound infection was similar in both groups (p = 0.7), although infection was more severe with open harvesting. Pain score was lower (p = 0.006) with endoscopic harvesting. CONCLUSIONS: Endoscopic radial artery harvesting was associated with better wound appearance and less pain. Occurrence of neurologic deficits and wound infection was infrequent in both groups.

Economic evaluation of coronary artery bypass grafting surgery with and without cardiopulmonary bypass: cost-effectiveness and quality-adjusted life years in a randomized controlled trial.

The objective of this study is to evaluate the costs and health benefits of coronary artery bypass grafting (CABG) surgery with and without cardiopulmonary bypass (CPB). Randomized controlled clinical trial is used as the design. The setting is in a single tertiary cardiothoracic center in Middlesex, UK. Participants were 168 patients (27 females) requiring primary isolated CABG surgery. Patients were randomized to have the procedure performed by a single surgeon either with CPB (n = 84) or by an off-pump coronary artery bypass (OPCAB) surgery (n = 84). Health-related quality of life was assessed at baseline, 6 weeks, and 6 months using the World Health Organization Quality-of-Life (WHOQOL-100) questionnaire. Mean total costs of patient management by either technique were calculated using different available key sources. A utility measure, derived from WHOQOL-100, was used to calculate quality-adjusted life year (QALY) gained in each group, on basis of which a cost-effectiveness analysis was performed. The mean total costs of an OPCAB patient was 5859 pounds , whereas for a CPB patient it was 7431 pounds with a mean difference of 1572 pounds (standard error [SE] 674 pounds ; P = 0.02). Three patients died in the CPB group and two in the OPCAB group during the 6-month follow-up period. Mean QALYs over 6 months was 0.379 in the OPCAB group and 0.362 in the CPB group, but the difference was not significant (mean difference 0.017; SE 0.016; P = 0.305). OPCAB surgery offered patients in this randomized trial similar health benefits to CPB over a 6-month period, but at a significantly less cost.

A three-dimensional echocardiographic comparison of a deep pericardial stitch versus an apical suction device for heart positioning during beating heart surgery.

BACKGROUND: Heart positioning during beating heart surgery produces significant haemodynamic compromise either when a deep pericardial stitch (DPS) or apical suction devices (ApSDs) are used. In this study the two techniques' haemodynamic performance and effect on intracardiac structures were compared through transoesophageal echocardiography (TEE) obtained volume measurements and three-dimensional ventricular and mitral valve computer reconstructions. METHODS: Sequential 0 degrees to 180 degrees TEE images of the left heart were obtained in 10 patients undergoing beating heart surgery. Measurements with both techniques in three different positions were obtained: at baseline, the heart elevated to access its inferior surface and the heart elevated and rotated to access its lateral surface. Three-dimensional computer reconstructions of the mitral valve and the left heart were generated. Ventricular volume measurements were used to calculate stroke volume, ejection fraction and differences from baseline. An analysis of variance between each technique in all three positions was performed. RESULTS: Central venous, left atrial and pulmonary artery pressures were significantly increased with either technique during positioning. Both techniques significantly affected left ventricular function decreasing stroke volume and ejection fraction. In the vertical and rotated position, the ApSD produced a significant decrease from baseline both in stroke volume (DPS: 32.8+/-18.7 vs ApSD: 55.46+/-21.7; p=0.02) and in ejection fraction (DPS: 19.3+/-10.5 vs ApSD: 40.9+/-24.6; p=0.02). The three-dimensional reconstructions demonstrated significant distortion of the atrioventricular geometry and the mitral valve, which was more pronounced with the DPS. CONCLUSION: Both techniques produce variable degrees of deformation with associated cardiac dysfunction and haemodynamic instability. Cardiac function is impeded more with an ApSD with the heart elevated and rotated.

Systemic venous thrombosis after recombinant factor VIIa in the control of bleeding after cardiac surgery.

Recombinant factor VIIa has been licensed in the United Kingdom since 1996 for the control of bleeding in hemophilic patients who are actively bleeding or are about to undergo surgery. Medical practitioners are also applying recombinant factor VIIa toward the control of bleeding in patients without hemophilia. Although the efficacy of recombinant factor VIIa has been shown in many patients, concerns have arisen about the risk of thrombotic adverse events. Herein, we report the case of a 73-year-old woman who underwent major coronary surgery and developed fatal systemic venous thrombosis after recombinant factor VIIa was used in an attempt to control her severe postoperative bleeding. We review the medical literature and discuss the risks of using recombinant factor VIIa to control severe bleeding after cardiac surgery.

Effect of myocardial reperfusion on the release of nitric oxide after regional ischemia: an experimental model of beating-heart surgery.

Off-pump coronary artery bypass surgery is increasing in popularity worldwide. However, very little is known about the effect of regional myocardial ischemia-reperfusion on nitric oxide release. In an animal model mimicking off-pump bypass, male Sprague-Dawley rats (350-450 g) were mechanically ventilated under general anesthesia. After left lateral thoracotomy, the animals underwent occlusion of either the left anterior descending artery (for 3, 5, 75, 10, 12.5, 15, or 20 minutes) or the circumflex artery (for 5, 10, or 15 minutes). Twenty-four hours after reperfusion, heart tissue was stained for determination of the area at risk and the infarcted area. Blood samples obtained before ischemia, 10 minutes after reperfusion, and 24 hours after reperfusion were analyzed for plasma concentrations of nitric oxide. After occlusion of the left anterior descending artery, the size of the infarcted area increased dramatically as the duration of occlusion increased, and was significantly larger after 12.5, 15, or 20 minutes of occlusion than after 3 minutes. After occlusion of the circumflex artery, the size of the infarcted area increased steadily and was significantly larger after 15 minutes of occlusion than after 5 minutes. There was no significant correlation between the duration of coronary occlusion and the plasma concentration of nitric oxide: 10 minutes after reperfusion, this concentration was significantly lower than that before ischemia, but it was twice the baseline level 24 hours after reperfusion. We concluded that the duration of regional ischemia did not affect the plasma concentration of nitric oxide in the systemic circulation.

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. CONCLUSIONS: 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.

Dobutamine improves thoracic aortic blood flow during off-pump coronary artery bypass surgery: results of a prospective randomised controlled trial.

OBJECTIVE: Dobutamine is commonly used to improve ventricular performance in cardiac surgery. The aim of this prospective randomised controlled study was to assess the effectiveness of using low doses of dobutamine during off-pump coronary artery bypass (OPCAB) surgery in order to reduce haemodynamic compromise due to heart displacement. METHODS: Thirty-two patients undergoing elective coronary artery bypass grafting (CABG) surgery using OPCAB technique for more than two vessels were approached and recruited. We analysed the changes in the thoracic aortic blood flow (TABF) during OPCAB using transoesophageal Doppler and by other conventional monitoring methods as cardiac output, invasive pulmonary and radial pressures and mixed venous oxygen saturation. RESULTS: The two groups were similar in preoperative characteristics. No postoperative complications were observed in the study patients. The heart rate, right atrial pressure, cardiac output measured by thermodilution and TABF changed significantly during the procedure. Also significant changes in descending thoracic aortic diameter were observed. The postoperative creatinine was significantly lower in the dobutamine group (P=0.04). Dobutamine was found responsible for the improvement in the descending TABF (P=0.006). CONCLUSIONS: This study showed that intra-operative intravenous infusion of dobutamine at 5 microg/kg per min in routine OPCAB patients safely increased cardiac output even without such changes been detected by conventional monitoring methods.

The early clinical and angiographic outcome of sequential coronary artery bypass grafting with the off-pump technique.

OBJECTIVE: The emergence of the off-pump coronary artery bypass technique has made surgeons consider combining it with other techniques developed and learned with conventional coronary artery bypass grafting with cardiopulmonary bypass. One of these techniques is the construction of a sequential graft to bypass more than one coronary vessel. The purpose of this study is to review the outcome of combining sequential coronary artery bypass grafting with off-pump techniques. METHODS: We retrospectively reviewed the records of 45 consecutive patients who underwent isolated coronary bypass surgery with off-pump and sequential grafting techniques at Harefield Hospital (Harefield, UK) between July 1999 and December 2000. The registry database, medical notes and charts were studied for preoperative and postoperative data of the patients. Ten patients consented and underwent early postoperative angiography to check the quality of the grafts and anastomoses. RESULTS: There were no deaths among the study patients. Morbidity consisted of atrial fibrillation in 6 patients (13.3%), leg wound infection in 2 patients (4.4%), and pleural effusion in 1 patient (2.2%). Early angiography of the 10 consenting patients revealed 10 patent sequential grafts (100%) with 20 satisfactory end-to-side and side-to-side anastomoses (100%). CONCLUSION: The combination of sequential grafting and off-pump techniques is feasible, is safe, and provides good early clinical and angiographic outcomes.

Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance--a three-dimensional echocardiography reconstruction study.

BACKGROUND: Positioning for access to the coronary arteries leads to hemodynamic instability during off-pump cardiac surgery. External changes have been well described, but a description of the intracardiac structures in humans has not been described. METHODS: With multiplane intraoperative echocardiography, the mitral annulus at end diastole was reconstructed in the different positions and correlated with hemodynamic changes in the right heart and left atrium. RESULTS: Significant distortion of the mitral annulus with enlargement of the left atrium and pulmonary veins was demonstrated, which correlated with high left atrial pressures. CONCLUSIONS: Mitral valve distortion can significantly contribute to hemodynamic instability during positioning for off-pump cardiac surgery.

Early clinical and angiographic outcome of the pedicled right internal thoracic artery graft to the left anterior descending artery.

BACKGROUND: The left internal thoracic artery (LITA) graft to the left anterior descending (LAD) artery became the gold standard graft in coronary surgery. Subsequently, the right internal thoracic artery (RITA) graft was increasingly used. However, there is still some debate about the optimal way of using this conduit. The aim of the present study was to assess our experience in grafting the pedicled RITA graft to LAD in 212 consecutive patients. METHODS: The records of 212 consecutive patients who underwent isolated coronary artery bypass grafting with the pedicled RITA graft to the LAD artery at Harefield Hospital between January 1998 and May 2001 were retrospectively reviewed. We approached the last 35 consecutive patients to obtain an angiographic control group. All 35 patients (16.5%) consented and, before discharge, underwent angiography to look at the quality of anastomoses and the patency of grafts. RESULTS: Successful catheterization and engagement of the RITA grafts was performed in 32 patients. Angiography showed that 32/32 (100%) of the RITA grafts were widely patent with excellent flow. The distal anastomoses of these RITA grafts were also satisfactory. There were no deaths among the study patients. CONCLUSIONS: Our results show that the use of the pedicled RITA graft to the LAD artery provides a good early clinical and angiographic outcome, and suggests that the pedicled RITA graft to the LAD artery is a good alternative to the pedicled LITA graft to the LAD artery.

Conversion to off-pump coronary bypass without increased morbidity or change in practice.

BACKGROUND: This article examines the feasibility of complete conversion from conventional coronary artery operation to routine off-pump coronary bypass operation. METHODS: Data on our first 285 off-pump procedures using the Octopus system (Medtronic Inc, Minneapolis, MN) represent our learning curve. This is a complete experience in coronary bypass surgery over 16 months. RESULTS: The cohort was nonselected. All patients had at least two-vessel disease. Eight hundred seven grafts were performed (mean, 2.8 per patient) of which 647 grafts (84%) were arterial (mean, 2.3 per patient). One hundred seventy nine patients (63%) underwent total arterial revascularization. Eight patients required cardiopulmonary bypass; all other operations were completed off-pump. Complications were: mortality, 3 patients (1.5%); renal failure, 24 patients (8%); stroke, 2 patients (< 1%); and atrial fibrillation, 60 patients (21%). The morbidity data and frequency of arterial grafting did not differ from that of 355 patients who underwent coronary bypass operations in a preceding 18-month period. CONCLUSIONS: Complete shift from routine use of cardiopulmonary bypass to nonselective off-pump coronary bypass operation is possible with a low conversion rate and without an apparent increase in morbidity or change in technique. Whereas short-term safety and efficacy seem certain, studies of long-term outcome are necessary before the eventual role of off-pump coronary bypass in myocardial revascularization can be defined.

Is the female gender an independent predictor of adverse outcome after off-pump coronary artery bypass grafting?

BACKGROUND: The female gender is an independent predictor of adverse outcome after conventional coronary artery bypass grafting using cardiopulmonary bypass. The aim of this study is to assess the effect of the female gender on the outcome after off-pump coronary artery bypass (OPCAB) surgery. METHODS: This study is a retrospective review of 413 consecutive patients (181 women and 232 men) who underwent OPCAB between January 1999 and May 2001. Adverse outcomes were divided into minor adverse outcomes (MINAO), major adverse outcomes (MAJAO), and prolonged length of stay (PLOS) more than 7 days. MINAO included atrial fibrillation, respiratory complications except adult respiratory distress syndrome, and any wound infection except mediastinitis. MAJAO included stroke, myocardial infarction, renal failure, adult respiratory distress syndrome, mediastinitis, low cardiac output, mechanical ventilation more than 24 hours, intensive therapy unit stay more than 24 hours, gastrointestinal complications, cardiorespiratory arrest, and mortality within 30 days. Preoperative and intraoperative variables were evaluated as predictors of MINAO, MAJAO, and PLOS by univariate and multivariate analyses. RESULTS: The groups were matched for age and Parsonnet score-predicted mortality. However, the women had a higher incidence of chronic obstructive airway disease (p = 0.04), diabetes (p = 0.01), obesity (p = 0.000), peripheral vascular disease (p = 0.000), hypertension (p = 0.000), unstable angina (p = 0.005), history of previous failed nonsurgical intervention (p = 0.02), and nonelective operation (p = 0.000). There were a fewer number of grafts performed in the female group (2.8 vs 3.4, p = 0.000), with the circumflex territory being revascularised less frequently (p = 0.001). Univariate analysis identified the female gender to be a predictor of only MINAO (p = 0.001) and PLOS (p = 0.000). However, with multivariate analysis, female gender was not found to be an independent predictor of MINAO, MAJAO, or PLOS. CONCLUSIONS: In OPCAB, the female gender is not an independent predictor of MINAO, MAJAO, or PLOS.

Use of radial artery graft reduces the morbidity of coronary artery bypass graft surgery in patients aged 65 years and older.

BACKGROUND: The use of the radial artery graft in patients aged 65 years and older could prevent the occurrence of leg wound infection, which is known to increase the morbidity of coronary artery bypass grafting surgery. METHODS: We reviewed, retrospectively, 261 patients aged 65 years and older (age range 65 to 93 years), who underwent coronary artery bypass grafting surgery between February 1998 and August 2001. All the patients received at least one radial artery graft in addition to either a left internal thoracic artery, right internal thoracic artery, or saphenous vein graft as required. Saphenous vein grafts were used in 141 (54.1%) patients (group 1), and these were compared to 120 (45.9%) patients (group 2) who received only arterial conduits. Angiography was performed on 26 consecutive patients. The aim of the study was to review the clinical and angiographic outcomes in this population. RESULTS: The mean number of distal anastomoses performed was 2.98. Mean global operating time was 204 minutes. This time dropped to 201 minutes in group 1 versus 231 minutes in group 2; p = 0.009. Sixteen (11.3%) patients receiving saphenous vein grafts had leg wound infection whereas only 1 (0.3%) patient of the global population had a forearm infection. The mean global hospital stay was 9.81 days; this duration increased to 13 days when leg wound infection occurred versus 9.1 days when infection did not occur; p = 0.008. Twenty-six (10%) patients underwent an early angiographic study. Twenty-four (92.3%) radial artery grafts were patent. CONCLUSIONS: The routine use of radial artery grafts in patients aged 65 years and older is feasible, safe, and does not increase mortality, morbidity, or the complexity of coronary artery bypass grafting surgery.

Differential in vitro response of the human radial artery versus left internal thoracic artery to cerivastatin: implications to bypass grafting.

BACKGROUND: This study investigated acute (in vitro) and long-term (in vivo) effects of statins on the vascular function of human radial artery (RA) and left internal thoracic artery (LITA). METHODS: RA and LITA specimens were divided into vascular rings, which were incubated in the absence or presence of 10(-6) mol/L Cerivastatin for 2 or 24 hours. In terms of preoperative statin treatment, four groups included: group 1 [preop statin(-)/in vitro cerivastatin(-)]; group 2 [preop(-)/in vitro(+)]; group 3 [preop(+)/in vitro(-)]; and group 4 [preop(+)/in vitro(+)]. Endothelial function was assessed with acetylcholine (10(-9) to 10(-5) mol/L) following contraction by 3 x 10(-8) mol/L endothelin-1. RESULTS: Although endothelium-dependent vasodilatation was higher in RA (57.7% +/- 3.5%) than in LITA (46.5% +/- 3.8%, p = 0.046), there was no significant evidence that it depended on the preoperative use of statins or incubation period. In vitro incubation with cerivastatin significantly increased endothelium-dependent vasodilatation by 14.2% +/- 2.4% (p < 0.0001) independent of artery types (RA/LITA). There was no significant evidence that endothelium-dependent vasodilatation depended on the preoperative use of statins or incubation period. CONCLUSIONS: In vitro incubation with cerivastatin preserved endothelial function more effectively than preoperative use of statins. This could have implications to perioperative use of statins for patients undergoing coronary surgery.

Off-pump myocardial revascularization is associated with less incidence of stroke in elderly patients.

Several recent studies have highlighted the potential benefits of using off-pump coronary artery bypass (OPCAB) surgery, particularly in high-risk patients. The aim of this meta-analysis is to assess the effect of OPCAB on the incidence of stroke compared with coronary artery bypass grafting using cardiopulmonary bypass (CPB) in elderly patients. We performed a meta-analysis of all observational studies, published in MEDLINE between 1999 and 2002 and a comparison between the OPCAB and CPB techniques in elderly patients was performed with the outcome of interest being the incidence of stroke. Elderly patients were defined as those aged 70 years or older. Nine studies are included in the meta-analysis. The total number of subjects included was 4,475 patients, of which, 1,253 underwent OPCAB (28%) and 3,222 (72%) underwent CPB. The meta-analysis showed that the OPCAB technique was associated with significantly lower incidence of stroke in elderly patients compared with the CPB technique (1% vs 3%), with an odds ratio of 0.38% to 95% (CI, 0.22 to 0.65). We did not identify any significant heterogeneity and funnel plot asymmetry between the studies included in the meta-analysis. Meta-regression analysis including variables predicting stroke, mortality, and study characteristics did not show any associations affecting the calculated odds ratio of stroke. Despite the fact that this is a meta-analysis of observational studies and adjustment for differences in baseline risk factors between OPCAB and CPB patients was not possible, we believe that this study suggests that the OPCAB technique might be associated with reduced incidence of stroke in the elderly patients undergoing coronary artery bypass grafting.

Expanded use of suction and stabilization devices in cardiothoracic surgery.

BACKGROUND: Recent developments in beating heart instrumentation have allowed surgeons to perform multivessel off-pump coronary artery bypass surgery by overcoming the factors that impair surgical performance (limited visualization, continuous movement of the target area, and hemodynamic instability during exposure of the inferior and posterior parts of the heart). We have explored the possibility of further expanding apical and epicardial suction devices beyond their ordinary use in coronary artery surgery. METHODS: A retrospective review of our cardiac surgery database was undertaken to identify the incidences in which these devices have been used in a somewhat novel manner in the field of cardiac surgery. RESULTS: During this time period we identified 20 instances in which either apical or epicardial suction devices were used alone or together. The nature of the procedures included dividing pericardial adhesions (pericardiectomy, n = 2; dividing adhesions in redo-coronary surgery, n = 4), securing epicardial hemostasis (penetrating cardiac trauma, n = 2; securing hemostasis during reexploration after cardiac surgery, n = 10), and facilitating epicardial microwave ablation (n = 2). On all 20 occasions the intended procedures were undertaken uneventfully. Furthermore, the use of apical and epicardial devices greatly facilitated the operative procedures and avoided the use of cardiopulmonary bypass on all occasions. CONCLUSIONS: In summary, we would like to highlight the expanding role for apical and epicardial suction devices to an area beyond coronary artery surgery in which we have found their use invaluable.

Circumflex artery stenosis induced by intraoperative radiofrequency ablation.

We report a case of circumflex artery stenosis after intraoperative radiofrequency ablation for permanent atrial fibrillation in a patient who had a previous mitral valve replacement. The patient presented with acute pulmonary edema and severe angina 1 year after an uneventful recovery. The patient underwent a diagnostic angiography that showed the presence of stenosis of a long segment of the circumflex artery, adjacent to the radiofrequency ablation site, which was reopened successfully by angioplasty. Intraoperative radiofrequency ablation caused circumflex artery stenosis. We believe that this complication could have been avoided by applying the radiofrequency ablation more distally between the left pulmonary veins and the mitral valve.