Minimally invasive coronary artery bypass grafting: an experimental perspective

Biochemical Changes in Cardiopulmonary Bypass in Cardiac Surgery: New Insights

Patients undergoing coronary revascularization with extracorporeal circulation or cardiopulmonary bypass (CPB) may develop several biochemical changes in the microcirculation that lead to a systemic inflammatory response. Surgical incision, post-CPB reperfusion injury and blood contact with non-endothelial membranes can activate inflammatory signaling pathways that lead to the production and activation of inflammatory cells, with cytokine production and oxidative stress. This inflammatory storm can cause damage to vital organs, especially the heart, and thus lead to complications in the postoperative period. In addition to the organic pathophysiology during and after the period of exposure to extracorporeal circulation, this review addresses new perspectives for intraoperative treatment and management that may lead to a reduction in this inflammatory storm and thereby improve the prognosis and possibly reduce the mortality of these patients.

Narrative review of the systemic inflammatory reaction to cardiac surgery and cardiopulmonary bypass

Background

Data from large cardiac surgery registries have been depicting a downward trend of mortality and morbidities in the last 20 years. However, despite decades of medical evolution, cardiac surgery and cardiopulmonary bypass still provoke a systemic inflammatory response, which occasionally leads to worsened outcome. This article seeks to outline the mechanism of the phenomenon.

Methods

A thorough review of the literature has been performed. Criteria for considering studies for this non‐systematic review were as follows: observational and interventional studies investigating the systemic inflammatory response to cardiac surgery, experimental studies describing relevant molecular mechanisms, and essential review studies pertinent to the topic.

Results

The intrinsic variability of the inflammatory response to cardiac surgery, together with its heterogenous perception among clinicians, as well as the arduousness to early discriminate high‐responder patients from those who will not develop a clinically relevant reaction, concurred to hitherto unconclusive randomized controlled trials. Furthermore, peremptory knowledge about the pathophysiology of maladaptive inflammation following heart surgery is still lacking.

Conclusions

Systemic inflammation following cardiac surgery is a frequent entity that occasionally becomes clinically relevant. Specific genomic differences, age, and other preoperative factors influence the magnitude of the response, which elements display extreme redundancy and pleiotropism that the target of a single pathway cannot represent a silver bullet.

Costs, Clinical Outcomes, and Health-Related Quality of Life of Off-Pump vs. On-Pump Coronary Bypass Surgery

BACKGROUND

Off-pump coronary bypass surgery avoids the potential complications of cardiopulmonary bypass. However, its acceptance depends on medical and economic outcome. The aim of this prospective non-randomised study was to compare functional and economic outcome of off-pump and on-pump surgery at 1-year follow-up.

METHODS

102 patients (pts) treated with either off-pump (60pts) or on-pump surgery (42pts) were studied. Pts with left ventricular dysfunction, recent myocardial infarction (<1 month), renal impairment, valve surgery, previous stroke or coagulopathy were excluded. Variable and fixed costs were obtained for each treatment group during operative and postoperative care. In-hospital endpoints included all-cause mortality and complications (defined as excessive bleeding [>6 units blood transfusion], peri-operative myocardial infarction, atrial fibrillation, stroke, and infection). All cause mortality; cost-effectiveness and quality of life were assessed 1 year after surgery.

RESULTS

The in-hospital mortality was similar in the two treatment groups. Off-pump group had significantly fewer postoperative complication rate (off-pump 41% vs. on-pump 72%, p=0.001). The mean in-hospital cost was lower for off-pump surgery (off-pump 6.515+/-926 euro vs. on-pump 9.872+/-1.299 euro, p<0.0001) as well as the mean length of hospital stay (off-pump 4.93+/-0.93 days vs. on-pump 6.58+/-1.04 days, p<0.0001). At 1 year, all cause mortality, quality of life indices, return to work rate and treatment satisfaction was similar in both groups.

CONCLUSION

Off-pump myocardial revascularization maintains the advantages of conventional surgery in terms of survival and freedom from cardiac events while reducing the in-hospital cost.

Effect of a miniaturized extracorporeal circulation (MECC™System) on liver function

Objective: To evaluate the effect of a miniaturized extracorporeal circulation system (MECC™System) compared to conventional extracorporeal circulation (ECC) regarding liver function in cardiac surgical patients. Methods: Double indicator dilution measurements were achieved by bolus injection of indocyanine green (ICG) for assessment of cardiac index (CI) and plasma disappearance rate of ICG (PDRig). Measurements were simultaneously performed preoperatively after induction of anaesthesia (T1), following admission on the ICU (T2) and 6 h postoperatively (T3). Results: CI and PDRig were markedly increased after cardiac surgery without significant differences between groups. The percentage increase in CI was significantly correlated to the percentage increase in PDRig in both groups. Conclusion: Liver function improved after cardiac surgery in both groups of patients, which may partly be explained by an increase in CI under mild inotrope support. Differences between the extracorporeal circuits with respect to PDRig appear to be minimal in a group of patients without pre-existing liver injury. Perfusion (2007) 22, 245—250.

Robot-assisted coronary artery bypass grafting improves short-term outcomes compared with minimally invasive direct coronary artery bypass grafting

BACKGROUND

Robot-assisted coronary artery bypass grafts (RACAB) utilizing the da Vinci surgical system are increasingly used and allow the surgeon to conveniently harvest internal mammary arteries (IMAs). The aim of this study was to compare the outcomes of off-pump RACAB and minimally invasive direct coronary artery bypass grafting (MIDCAB) in the short and medium term.

METHODS

We performed a retrospective review of 132 patients with single- or multiple-vessel coronary artery disease who underwent minimally invasive off-pump CABG (OPCAB) between May 2009 and May 2014. The patients were divided into two groups based on the surgical approach, MIDCAB and RACAB group. The anastomosis of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) was performed as regular OPCAB through the incision on the beating heart using regular stabilization devices (Genzyme Corporation). The preoperative, intraoperative, postoperative, and follow-up data, including major adverse cardiac and cerebrovascular events (MACCE), were compared.

RESULTS

The preoperative data were similar. RACAB significantly shorten the intensive care unit (ICU) stay and postoperative compared with the MIDCAB group (P<0.05). There were 12 (19.7%) patients treated with a two-stage hybrid procedure in the MIDCAB group and 34 (47.9%) patients in the RACAB group (P=0.001). Thirty-day mortality was 1.6% in the MIDCAB group. There were 9 (14.7%) MIDCAB patients and 2 (2.8%) RACAB patients (P=0.013) that developed new arrhythmia. The two groups showed comparable mid-term survival (P=0.246), but the MACCEs were significantly different (P=0.038).

CONCLUSIONS

RACAB may be a valuable alternative for patients requiring single or simple multi-vessel coronary artery bypass grafting (CABG). Although the mid-term mortality outcomes are similar, RACAB improves short-term outcomes and mid-term MACCE-free survival compared with MIDCAB.

Impact of age on early outcome after coronary bypass graft surgery using minimized versus conventional extracorporeal circulation

Background

Objective of this study was to evaluate the impact of age on comparative early outcomes after coronary artery bypass graft surgery (CABG) with minimized (MECC) and conventional extracorporeal circulation (CECC).

Methods

A retrospective age-, gender- and operation-matched cohort analysis between January 2005 and December 2010 with a total of 2274 patients undergoing CABG with MECC (n = 1137; 50%) or CECC was performed. Patients were stratified into 4 groups according to age: <59 years, 60–69 years, 70–79 years, and 80 years of age or older. Outcomes were compared within each age group. Patients with preoperative dialysis were excluded from analysis. Primary endpoint was 30-day mortality.

Results

Patients treated with CECC had a significantly higher mean logistic EuroSCORE (6.3% vs. 5.0%; p < 0.001), a slightly lower rate of preoperative myocardial infarction (46% vs. 51%; p = 0.01) and a higher rate of impaired renal function (eGFR < 60 mL/min/1.73 m2: 24% vs. 20%; p = 0.01) compared to MECC-patients. Left internal mammary artery was significantly used more often in MECC patients (93% vs. 86%; p < 0.001). Cardiopulmonary bypass and aortic-cross clamping time were significantly lower in the MECC group (p < 0.001). Overall 30-day mortality was significantly higher in patients treated with CECC (4.4% vs. 2.2%; p = 0.002). Within the different age groups mortality rates were not significantly different except for patients aged 60–69 years (4.5% vs. 1.8%; p = 0.03). Postoperative requirement of renal replacement therapy (4% vs. 2.2%; p = 0.01), respiratory insufficiency (9.9% vs. 6.6%; P = 0.004) and incidence of low cardiac output syndrome (3% vs. 1.2%; p = 0.003) were significantly increased in patients with CECC. Multivariate analysis identified age (p = 0.005; 95% CI 1.01 to 1.08; OR 1.05) among other parameters as an independent risk factor, whereas conventional extracorporeal circulation itself did not present as an independent risk factor for 30-day mortality.

Conclusions

In this matched study sample early outcome was significantly better in patients with MECC compared to CECC, irrespective of age. Prior myocardial infarction estimated GFR < 60 mL and waiving the use of LIMA were independent risk factors for 30-day mortality, which were more present in the CECC group.

Hybrid coronary revascularization using limited incisional full sternotomy coronary artery bypass surgery in multivessel disease: early results

Background

There are several modalities of coronary artery revascularization for multivessel coronary artery disease. Hybrid coronary revascularization (HCR) with minimally invasive direct coronary artery bypass grafting was introduced for high-risk patients, and recently, many centers have been using it. Limited incisional full sternotomy coronary artery bypass (LIFCAB) involves left internal thoracic artery (LITA)-to-left anterior descending coronary artery (LAD) anastomosis through a sternotomy with a minimal skin incision; it could be considered another technique for minimally invasive LITA-to-LAD anastomosis. Our center has performed HCR using LIFCAB, and in this paper, we report our short-term results, obtained in the past 3 years.

Methods

The medical records of 38 patients from May 2010 to June 2013 were analyzed retrospectively. The observation period after HCR was 1 to 37 months (average, 18.3±10.3 months). The patency of revascularization was confirmed with postoperative coronary angio-computerized tomography or coronary angiography.

Results

There were 3 superficial wound complications, but no mortalities. All the LITA-to-LAD anastomoses were patent in the immediate postoperative and follow-up studies, but stenosis was detected in 3 cases of percutaneous coronary intervention.

Conclusion

HCR using LIFCAB is safe and yields satisfactory results from the viewpoint of revascularization for multivessel disease.

Safe introduction and quality control of new methods in coronary surgery

Introduction:

The first part of the paper analyses off pump coronary bypass surgery (OPCAB), which is compared with traditional on-pump procedures (ONCAB). Furthermore ,the paper evaluates the use of a new automatic device for performance of the proximal anastomosis and finally the effect of intracoronary shunt on myocardial ischemia during OPCAB. The main goal of the paper is to demonstrate the importance of careful clinical studies during introduction of the new techniques in cardiac surgery.

Methods:

Statistical analysis was performed on a large clinical database from Buffalo, NY, USA comparing OPCAB and ONCAB. Subsequently, a sequential controlled clinical study compared patients operated with a new automatic connector device to patients operated with classic suture technique. Finally a randomized study was performed to evaluate the effect of the use of an intracoronary shunt during construction of distal anastomosis.

Results:

The studies from Buffalo demonstrated reduced complications rates in high risk patients when OPCAB techniques were used. The use of connector devices in saphenous venous anastomosis was clearly inferior to standard technique. Intracoronary shunt was found to be beneficial by preventing ischemia.

Discussion:

Numerous studies have studied the results of OPCAB vs ONCAB and although results are variable it seems that OPCAB is advantageous in high risk patients, while in low risk patients there are much less if any benefit. The results of the studies of connector devices caused the product to be taken off the market. The value of shunt in OPCAB was clearly demonstrated by the randomized studies.

Conclusion:

The investigations presented in this paper clearly demonstrates the importance of well-designed studies when new surgical methods are introduced. In the present period of rapid technological development, carefully controlled, un-biased clinical trials are crucial to preserve patient safety and avoid unjustified societal cost.

Patency, flow, and endothelialization of the sutureless Excimer Laser Assisted Non-occlusive Anastomosis (ELANA) technique in a pig model

OBJECT

The purpose of this study was to assess flow, patency, and endothelialization of bypasses created with the sutureless Excimer Laser Assisted Non-occlusive Anastomosis (SELANA) technique in a pig model.

METHODS

In 38 pigs, a bypass was made on the left common carotid artery (CCA), using the right CCA as a graft, with 2 SELANAs. Bypass flow was measured using single-vessel flowmetry. The pigs were randomly assigned to 1 of 12 survival groups (1, 2, 3, 4, 5, 6, 7, and 10 days; 2 and 3 weeks; and 3 and 6 months). One extra animal underwent the procedure and then was killed after 1 hour of bypass patency to serve as a control. Angiography was performed just before the animals were killed, to assess bypass patency. Scanning electron microscopy and histological studies were used to evaluate the anastomoses after planned death.

RESULTS

The mean SELANA bypass flow was not significantly different from the mean flow in the earlier ELANA (Excimer Laser Assisted Non-occlusive Anastomosis) pig study at opening and follow-up. Overall SELANA bypass patency (87%) was not significantly different from the ELANA patency of 86% in the earlier study. Complete SELANA endothelialization was observed after 2-3 weeks, compared with 2 weeks in the earlier ELANA study.

CONCLUSIONS

The SELANA technique is not inferior to the current ELANA technique regarding flow, patency, and endothelialization. A pilot study in patients is a logical next step.

The inflammatory response to miniaturised extracorporeal circulation: a review of the literature

Conventional cardiopulmonary bypass can trigger a systemic inflammatory response syndrome similar to sepsis. Aetiological factors include surgical trauma, reperfusion injury, and, most importantly, contact of the blood with the synthetic surfaces of the heart-lung machine. Recently, a new cardiopulmonary bypass system, mini-extracorporeal circulation (MECC), has been developed and has shown promising early results in terms of reducing this inflammatory response. It has no venous reservoir, a reduced priming volume, and less blood-synthetic interface. This review focuses on the inflammatory and clinical outcomes of using MECC and compares these to conventional cardio-pulmonary bypass (CCPB). MECC has been shown to reduce postoperative cytokines levels and other markers of inflammation. In addition, MECC reduces organ damage, postoperative complications and the need for blood transfusion. MECC is a safe and viable perfusion option and in certain circumstances it is superior to CCPB.

Mechanical manipulator for intuitive control of endoscopic instruments with seven degrees of freedom

Performing complex tasks such as vascular anastomosis in minimally invasive surgery (MIS) is demanding due to a disturbed hand-eye co-ordination, the application of non-ergonomic instruments with limited number of degrees of freedom (DOFs) and a lack of three-dimensional perception. Robotic tele-manipulatory systems enhance surgical dexterity by providing up to seven DOFs. They allow the surgeon to operate in an ergonomically favourable position with more intuitive manipulation of the instruments. Robotic systems, however, are very bulky, expensive and do not provide any force feedback from the tissue. The aim of our study is to develop a simple mechanical manipulator for MIS. The Minimally Invasive Manipulator (MIM) is a purely mechanical device. When manipulating the handle of the MIM, the surgeon's wrist and grasping movements, which are essential for suturing, are directly transmitted to the deflectable instrument tip in seven DOFs. It gives the surgeon direct control of the instrument tip. First phantom experience indicates that the system functions properly. The MIM provides force feedback to improve safety. A set of MIMs seems to be an economical and compact alternative to robotic systems and will offer more surgeons the capability to perform complex MIS and to shorten their learning curve.

Development of laparoscopic instruments

Laparoscopy has important consequences for the functioning of the surgeon, affecting both his/her perception and manipulation capabilities. To be able to judge the perception and manipulation aspects of laparoscopic instruments, a thorough insight into the functioning of the laparoscopic surgeon is needed, and a realistic model of the operation process should be a starting point for every new design. In addition, it is efficient to use observational methods to gain insight into the most important limitations encountered in clinical practice and into the effect of an alternative design. To achieve simplification of the laparoscopic procedure, innovative and unconventional solutions are needed. Thus, the design strategy for laparoscopic instruments is important. Passive and active design strategies, and force- and motion-directed design concepts are reviewed, and their characteristics are compared in view of minimally invasive application. Three design examples are presented and the related design strategy is discussed in each case. These examples are: a laparoscopic grasper with force perception, a passive instrument positioner and a force-controlled robotic system with active constraints. Future trends in the development of laparoscopic instruments are also discussed.

Comparison of bypass surgery with drug‐eluting stents for diabetic patients with multivessel disease

BACKGROUND

This retrospective study of prospectively collected data compared coronary artery bypass graft (CABG) surgery to drug-eluting stenting (DES) in diabetic patients with multivessel coronary artery disease (CAD). Prior randomized trials and clinical studies have suggested that CABG may be the preferred revascularization strategy in diabetic patients with multivessel CAD. Data are limited regarding the impact of DES vs. CABG on clinical outcomes.

METHODS

We included 205 consecutive diabetic patients who underwent either CABG (n=103) or DES (n=102). The primary clinical end points were freedom from major adverse cardiac events (MACE) at 30 days and 1 year.

RESULTS

Baseline characteristics were similar between both groups. At 1 year, the mortality rate was similar in the CABG and DES group (8% vs. 10%, p=0.6) but the MACE rate was lower in the CABG group (12% vs. 27%, p=0.006) due to less repeat revascularization with CABG (3% vs. 20%, p<0.001). Stroke occurred only in the CABG group (4% vs. 0%, p=0.04). Angiographically-documented stent thrombosis after DES occurred in 3%. Presentation with acute myocardial infarction (hazard ratio [HR], 2.26, 95% CI, 1.13 to 4.55) and DES (HR, 2.4, 95% CI, 1.23 to 4.77) were positive independent predictors, whereas therapy with a statin was a negative independent predictor of MACE (HR, 0.40, 95% CI, 0.21 to 0.76).

CONCLUSIONS

Bypass surgery was associated with less MACE primarily due to the higher repeat revascularization rate with DES and is therefore superior to DES despite more extensive CAD in CABG patients.

Deep pericardial suture vs apical suction for off-pump bypass grafting

Hemodynamic changes during heart luxation and stabilization are major problems in off-pump coronary artery bypass surgery. The hemodynamic effects of an apical suction device were compared with those of the classic posterior pericardial suture in 45 patients with multivessel coronary disease undergoing off-pump coronary artery bypass. Mean age was 63.78 +/- 8.11 years; 31 patients were male and 14 were female. Transesophageal Doppler echocardiography was used for hemodynamic monitoring. All hemodynamic parameters were significantly better when the apical suction device was used to position the heart for anastomoses on the posterior descending and circumflex arteries.

A miniature cable-driven robot for crawling on the heart

This document describes the design and preliminary testing of a cable-driven robot for the purpose of traveling on the surface of the beating heart to administer therapy. This methodology obviates mechanical stabilization and lung deflation, which are typically required during minimally invasive cardiac surgery. Previous versions of the robot have been remotely actuated through push-pull wires, while visual feedback was provided by fiber optic transmission. Although these early models were able to perform locomotion in vivo on porcine hearts, the stiffness of the wire-driven transmission and fiber optic camera limited the mobility of the robots. The new prototype described in this document is actuated by two antagonistic cable pairs, and contains a color CCD camera located in the front section of the device. These modifications have resulted in superior mobility and visual feedback. The cable-driven prototype has successfully demonstrated prehension, locomotion, and tissue dye injection during in vitro testing with a poultry model.

Risk and determinants of myocardial injury during off-pump coronary artery bypass grafting

Perioperative myocardial injury (PMI) after coronary revascularization (bypass surgery using cardiopulmonary bypass or percutaneous intervention) is strongly associated with future adverse events, such as death, myocardial infarction, and coronary intervention. The incidence, determinants, and prognostic significance of PMI after bypass surgery without cardiopulmonary bypass (off-pump surgery) are unknown. The study population comprised the patients who were randomized to off-pump surgery in the Octopus Study. PMI was defined by a creatine kinase isoenzyme-MB/total creatine kinase ratio of >5% during the first 48 hours, postoperatively. PMI occurred in 137 of 260 patients (52%). Using multivariate regression analysis, age, female gender, previous myocardial infarction, preoperative nitrate use, preoperative diuretic use, and number of grafts were independently associated with an increased risk of PMI during off-pump surgery. The presence of preoperative coronary collaterals showed a negative association with PMI. The occurrence of PMI had a crude odds ratio of 7.53 (95% confidence interval 1.59 to 35.63) for an adverse cardiac event at 1 year after off-pump surgery. This odds ratio changed little after adjustment for confounders (odds ratio 6.39, 95% confidence interval 1.41 to 28.93). In conclusion, more severe atherosclerotic disease and female gender were associated with an increased risk of perioperative myocardial injury during off-pump bypass surgery, although the presence of coronary collaterals appeared to be protective. Patients with perioperative myocardial injury during off-pump surgery were at a higher risk of adverse cardiac outcomes at 1 year.

Midterm Results of Off-Pump Coronary Artery Bypass Surgery in 136 Patients: An Angiographic Control Study

BACKGROUND

Off-pump coronary artery bypass surgery may provide an alternative form of surgical revascularization by avoiding the complications of cardiopulmonary bypass (CPB). This study summarizes the midterm results of 136 off-pump bypass surgery patients.

METHODS

Between January 2000 and March 2002, out of 178 surgical myocardial revascularizations, 136 (76.4%) were off-pump bypass surgery. Complete revascularization was done and especially arterial grafts were used. All patients were followed clinically and with treadmill test for 2 years. Average control angiography was performed at the end of 2-year follow-up.

RESULTS

Of all the patients, 56.7% were male and the mean age of the patients was 63.6 +/- 7.4 years. A total of 481 anastomoses were performed-136 (28.27%) to the left anterior descending artery (LAD), 135 (28.07%) to the circumflex coronary artery (Cx) branches, 102 (21.20%) to the right coronary artery (RCA), 108 (22.46%) to the Di. The mean graft number was 3.46. We used 96.6% of patients' left internal mammarian artery (LITA), 29.2% radial artery (RA), 4.4% right internal thoracic artery (RITA), and 100% saphenous vein. There were ischemic changes within 12 patients. All ischemic changes came back to normal within 4 and 18 hours, postoperatively. Mean extubation time was 5.36 +/- 2.23 hours, mean stay in intensive care unit was 17.53 +/- 3.15 hours, mean hospital stay was 5.03 +/- 1.29 days. The LITA patency was 99.25%, RA patency was 97.84%, RITA patency was 100%, and saphenous vein patency was 91.79% with control angiography.

CONCLUSION

Off-pump coronary artery bypass graft (CABG) is efficient procedure with lower index of mortality, morbidity, ICU stay, hospital stay, good wound healing, early socialization, and results in lower costs.

The Relation Between Surgeon Volume and Outcome Following Off-Pump vs On-Pump Coronary Artery Bypass Graft Surgery

STUDY OBJECTIVE

Off-pump coronary artery bypass graft (CABG) surgery has been recently reintroduced into clinical practice. In light of the relatively low level of experience of most cardiac surgeons with off-pump CABG surgery, and the exceptional technical challenge of working on a "beating heart," off-pump CABG surgery presents a unique opportunity to explore the effect of surgeon case volume on surgical outcome after controlling for the effects of patient case mix and hospital volume.

DESIGN

A retrospective cohort study analyzing the association between surgeon volume and in-hospital mortality rate for off-pump and on-pump CABG surgery using random-effects logistic regression modeling.

SETTING AND PATIENTS

The analyses were based on the New York State clinical CABG surgery registry. The study sample consisted of 36,930 patients undergoing isolated CABG surgery between 1998 and 1999 that was performed by 181 surgeons at 33 hospitals.

INTERVENTIONS

None.

RESULTS

There is no association between the number of CABG procedures performed off-pump by an individual surgeon and in-hospital mortality rates (p = 0.93) after controlling for hospital CABG surgery volume and patient-level risk factors. There is also no association between the off-pump CABG surgery mortality rate and the total number of both off-pump and on-pump CABG surgery cases (p = 0.78). In the on-pump CABG surgery cohort, surgeons performing a high volume of CABG procedures had significantly lower risk-adjusted mortality rates among their patients compared to those performing a very low volume, a low-volume, and a medium volume of CABG procedures (p < 0.006).

CONCLUSION

For off-pump CABG surgery, surgeons performing a high volume of procedures do not have better mortality outcomes than those performing a low volume of procedures. However, higher surgeon case volumes are associated with lower mortality rates for on-pump CABG surgery. The absence of a volume-outcome association for off-pump CABG surgery is especially surprising in light of the more technically demanding nature of off-pump CABG surgery compared to on-pump CABG surgery.

Ineffectiveness of Local Wound Anesthesia to Reduce Postoperative Pain After Median Sternotomy

Postoperative pain control still represents a major challenge in every surgical field. Bupivacaine wound infiltration is frequently used to reduce the pain related to the surgical incision itself. In this randomized study, we investigated the efficacy of bupivacaine local anesthesia after median sternotomy to reduce postoperative pain. Forty-seven patients undergoing major cardiac surgery procedures were allocated randomly to group A (bupivacaine wound infiltration 0.5%; 10 mL, followed by continuous infusion: 10 mg/24 H) or to group C (controls). Extubation time, postoperative arterial blood gases, postoperative pain (assessed by means of a visual analog scale), and morphine consumption were the endpoints of the study. Patients of group C were extubated earlier; blood gases and VAS values were similar in both group. Bupivacaine local analgesia did not improve postoperative pain control after median sternotomy.

Four years' experience with a miniaturized extracorporeal circulation system and its influence on clinical outcome

It has been suggested that the morbidity associated with cardiopulmonary bypass can be attributed in part to the blood-material and blood-air interactions in the extracorporeal circulation (ECC). A recently introduced minimized ECC-system (MECC System) should be able to reduce these negative effects associated with ECC. A retrospective analysis was performed comprising 485 patients who were operated on for elective coronary artery bypass grafting (CABG) using the MECC System with intermittent antegrade warm blood cardioplegia (group 1) from January 2000 to February 2004. A control group consisted of 485 patients (group 2) undergoing elective CABG in the same period using a conventional ECC and cold crystalloid cardioplegia. There were no significant differences between the two groups in terms of the duration of intubation following surgery, the length of intensive care unit-stay and the total hospital stay. Although the 30-day mortality was similar between the two groups, the incidence of postoperative complications and the perioperative use of blood products were significantly higher in the control group compared to the MECC group. The MECC System may serve as an alternative and less invasive approach to conventional ECC.

Novadaq SPY: intraoperative quality assessment in off-pump coronary artery bypass grafting

OBJECTIVES

Off-pump coronary artery bypass grafting may decrease operative morbidity when compared to on-pump bypass grafting; however, it is technically demanding and thus quality control is essential. This study assesses the clinical feasibility of a new, indocyanine green (ICG)-based imaging system (SPY; Novadaq Technologies; Toronto, ON, Canada) to monitor the quality of anastomoses and grafts in off-pump revascularization.

SETTING

Thirty-eight consecutive patients undergoing nonemergent coronary artery bypass grafting without the use of extracorporeal circulation at two Swiss cardiac surgery clinics were included. On completion of bypass grafts, the quality of the grafts was assessed using the ICG-based imaging system. The imaging device comprises an 806-nm laser light source that is used to cause ICG to fluoresce and a near infrared-sensitive charged couple device videocamera that is used to capture the fluorescence images. ICG was administered through the central venous line, and images were acquired during the first pass of the ICG through the field of view. Graft flow (qualitative) and the quality of the grafts and anastomoses were assessed intraoperatively.

RESULTS

Between March 2002 and September 2002, a total of 38 patients (26 men and 12 women; mean +/- SD age, 64.6 +/- 10.5 years; body mass index, 27.1 +/- 2.9) underwent surgery and imaging at two institutions. One hundred seven of 124 grafts (45 arteries and 62 veins) were analyzed. Seventeen grafts could not be assessed due to difficulties in positioning. The imaging system was easy to handle, and no adverse reactions to ICG were observed. Four of the 107 grafts imaged required revision (three anastomotic constrictions and one graft dissection). Each imaging sequence required approximately 1.25 to 2.5 mg of ICG. The images were equivalent to angiography without the need for radiographs and catheter insertion. In addition, the course of coronaries that would otherwise be difficult to locate in obese patients could be detected using the imaging system. Biochemical and ECG data demonstrated an absence of intraoperative or postoperative myocardial damage, and no liver enzyme elevation or renal dysfunction.

CONCLUSIONS

This study supports the clinical utility of a ICG-based imaging system for the assessment of the quality of bypass grafts, which appears to be safe and simple to use.

Mechanical properties of porcine and human arteries: implications for coronary anastomotic connectors

BACKGROUND

To determine whether the pig is an appropriate experimental animal for studies on distal anastomotic connectors in coronary artery bypass surgery, the mechanical properties of young porcine and old human coronary and internal mammary arteries were compared within and beyond the physiologic range of strains.

METHODS

Coronary arteries from 6 humans and 8 pigs were studied as well as internal mammary arteries of 3 humans and 6 pigs (human, aged 61 to 85 years; pig, 78.7 +/- 5.8 kg [mean +/- SD]). Pressure-diameter, pressure-axial force, circumferential and axial stress-strain relations, and dimensions were measured.

RESULTS

The dimensions of the porcine and human coronary and internal mammary artery were generally similar but wall thickness was smaller in the porcine internal mammary artery (0.35 +/- 0.07 mm versus 0.71 +/- 0.06 mm, respectively, p = 0.002). The porcine internal mammary artery wall was less elastic than the coronary artery wall, whereas in humans both arteries displayed similar elasticity. Overall the porcine arteries were far more elastic in both circumferential and axial direction compared with the human arteries. Consequently the porcine arteries could be safely stretched by 60% to 70% compared with about 20% for the human arteries before reaching their maximum circumferential strain.

CONCLUSIONS

The three times greater elasticity of porcine compared with human coronary and internal mammary artery walls may result in underestimation of wall stress and the risk of wall injury when coronary connectors that involve overstretching of the wall are evaluated in the pig.

Revascularization in multivessel disease: comparison between two-year outcomes of coronary bypass surgery and stenting

OBJECTIVE

The recent appreciation that stenting has improved the short- and long-term outcomes of patients treated with coronary angioplasty has made it imperative to reconsider the comparison between surgery and percutaneous interventions in patients with multivessel disease.

METHODS

One thousand two hundred five patients were randomly assigned to undergo bypass surgery or angioplasty with stent implantation when there was consensus between the cardiac surgeon and interventional cardiologist as to equivalent treatability. The primary clinical end point was freedom from major adverse cardiac and cerebrovascular events at 1 year. Major adverse cardiac and cerebrovascular events at 2 years constituted a secondary end point.

RESULTS

At 2 years, 89.6% of the surgical group and 89.2% of the stent group were free from death, stroke, and myocardial infarction (log-rank test P =.65). Among patients who survived without stroke or myocardial infarction, 19.7% in the stent group underwent a second revascularization, as compared with 4.8% in the surgical group (P <.001). At 2 years, 84.8% of the surgical group and 69.5% of the stent group were event-free survivors (log-rank test P <.001), and 87.2% in the surgical cohort and 79.6 % in the stent group were angina-free survivors (P =.001). In the diabetes subgroup, 82.3% of the surgical group and 56.3% of the stent group were free from any events after 2 years (log-rank test P <.001).

CONCLUSION

The difference in outcome between surgery and stenting observed at 1 year in patients with multivessel disease remained essentially unchanged at 2 years. Stenting was associated with a greater need for repeat revascularization. In view of the relatively greater difference in outcome in patients with diabetes, surgery clearly seems to be the preferable form of treatment for these patients.

Impact of restenosis and disease progression on clinical outcome after multivessel stenting in diabetic patients

Clinical outcome after percutaneous coronary intervention (PCI) is significantly worse in diabetic patients in comparison to nondiabetic patients. The subset of diabetic patients in the ARTS trial treated with multivessel stenting had the lowest 1-year event-free survival. We examined our experience of multivessel PCI in diabetics to assess clinical outcome outside clinical trials and to determine if repeat revascularizations are the result of restenosis or the progression of nontreated disease. Between January 2000 and December 2001, we performed multivessel PCI in 99 diabetic patients. Our group was well matched with those in the ARTS trial, with mean age of 69 +/- 8 years, male sex 70%, hypertension 68%, hypercholesterolemia 51%, and mean LV ejection fraction 60%. The mean number of diseased segments treated was 2.8 +/- 0.9 and 56% of the patients had three-vessel disease. There were 2.3 +/- 0.6 stents implanted per patient. Target vessels included the LAD in 90%, LCx in 77%, and the RCA in 87% of cases. The in-hospital MACE rate was 8%, which included eight nonfatal MI but no deaths or repeat revascularizations. After a mean follow-up of 14 +/- 8 months, there were 4 deaths (4%), no further MIs, and 21 (21%) repeat revascularizations (2 CABG; 19 PCI), giving a 1-year event-free survival of 67%. There were 18 repeat revascularizations (2 CABG; 16 PCI) for restenosis, but in 9 of the 18 (50%) patients treatment was also required for progression of disease. Three further patients had PCI for symptomatic disease progression without restenosis. Thus, disease progression contributed to 57% of repeat revascularization procedures. The medium- and longer-term success of multivessel PCI in diabetic patients is limited principally by the need for repeat revascularization. However, it is important to realize that these revascularizations are performed not only for restenosis but also for disease progression in more than 50% of patients. Consequently, even if drug-eluting stent technology can eliminate restenosis, disease progression will continue to impact the clinical outcome of diabetic patients after PCI.

A comparison of on-pump and off-pump coronary bypass surgery in low-risk patients

BACKGROUND

The performance of coronary bypass surgery without cardiopulmonary bypass ("off pump") may reduce perioperative morbidity and costs, but it is uncertain whether the outcome is similar to that involving the use of cardiopulmonary bypass ("on pump").

METHODS

In a multicenter, randomized trial, we randomly assigned 139 patients with predominantly single- or double-vessel coronary disease to on-pump surgery and 142 to off-pump surgery. Cardiac outcome and cost effectiveness were determined one year after surgery. The uncertainty surrounding the cost-effectiveness ratio (cost differences per quality-adjusted year of life gained) was addressed by bootstrapping.

RESULTS

At one year, the rate of freedom from death, stroke, myocardial infarction, and coronary reintervention was 90.6 percent after on-pump surgery and 88.0 percent after off-pump surgery (absolute difference, 2.6 percent; 95 percent confidence interval, - 4.6 to 9.8). Graft patency in a randomized subgroup of patients was 93 percent after on-pump surgery and 91 percent after off-pump surgery (absolute difference, 2.0 percent; 95 percent confidence interval, - 6.5 to 10.4). On-pump surgery was associated with $1,839 in additional direct costs per patient ($14,908 vs. $13,069--a difference of 14.1 percent) and an increase in quality-adjusted years of life of 0.83 as compared with 0.82 (difference, 0.01 year; 95 percent confidence interval, - 0.03 to 0.04). Off-pump surgery was more cost effective than on-pump surgery in 95 percent of bootstrap estimates.

CONCLUSIONS

In low-risk patients, there was no difference in cardiac outcome at one year between those who underwent on-pump bypass surgery and those who underwent off-pump surgery. Off-pump surgery was more cost effective.

The hybrid approach to coronary artery revascularization: minimally invasive direct coronary artery bypass with percutaneous coronary intervention

In the past decade, new developments in cardiology and cardiac surgery have begun to offer patients a variety of new, less invasive options for the treatment of coronary artery disease. One such option is the hybrid approach to coronary artery revascularization. This combines minimally invasive direct coronary artery bypass surgery (MIDCAB) of the left anterior descending artery (LAD) with percutaneous coronary intervention (PCI) of the remaining diseased coronary arteries. This approach, as an alternative to conventional coronary artery bypass surgery, retains the benefit of internal mammary artery bypass to the LAD, accomplished with a minimally invasive technique, substitutes PCI for saphenous vein grafts as treatment for low-grade lesions of other coronary arteries, and may provide a maximally beneficial outcome for many patients. Preliminary outcomes of patients receiving the hybrid approach have been strikingly positive. This report highlights the rationale for the development of this procedure, patient selection, results, and future applications of this emerging method of treating coronary artery disease.

Routine immediate extubation for off-pump coronary artery bypass grafting without thoracic epidural analgesia

BACKGROUND

The expansion of coronary surgery on the beating heart without cardiopulmonary bypass has led to increasing interest in ultra-fast track anesthesia, allowing extubation of the patient in the operating theater. The techniques described to date combined general anesthesia with thoracic epidural analgesia. We report the routine application of a technique that allows immediate extubation in the majority of patients undergoing off-pump coronary artery bypass grafting without thoracic epidural analgesia.

METHODS

Fast-track anesthesia using an ultra-shortacting opiate remifentanil, without epidural catheter insertion, was used in 160 unselected patients undergoing off-pump coronary artery bypass grafting (aged 43 to 83 years, mean 65 years). There were an average of 2.2 bypass procedures per patient, with the left internal mammary artery used in 93%. Contraindications to immediate extubation were (except for failure to meet standard extubation criteria) hemodynamic instability and persistent bleeding at the end of operation. Satisfactory postoperative pain control was achieved by continuous remifentanil (0.0125 to 0.05 microg x kg(-1) x min(-1)).

RESULTS

Operating theater extubation within 10 minutes of the end of operation was feasible in 150 patients (94%). Five patients (3%) were extubated within 2 hours, and the remaining 5 patients (3%) were converted to standard anesthesia. There were no deaths during hospitalization. Major complications included myocardial infarction and transient ischemic attacks (2 patients each). No pulmonary complications were seen. Episodes of atrial fibrillation occurred in 21% of the patients undergoing operation.

CONCLUSIONS

Immediate extubation is possible in most patients after off-pump coronary artery bypass grafting even without thoracic epidural analgesia. We believe this type of less invasive cardiac anesthesia is safe and promising.

Validation of a preoperative risk index as a predictor of perioperative morbidity and hospital costs in coronary artery bypass graft surgery

OBJECTIVE

To validate a previously developed model (CABDEAL) for predicting postoperative morbidity for coronary artery bypass graft (CABG) surgery patients using the New York State Statewide Planning and Research Cooperative System (SPARCS) database and to examine the effects of preoperative risk factors, postoperative complications, and death on costs of care for CABG surgery.

DESIGN

Retrospective database review.

SETTING

Governmental agency database of cardiac surgery.

PARTICIPANTS

CABG surgery patients (n = 15,388).

INTERVENTIONS

A previously developed preoperative risk model (CABDEAL) was applied to all patients. Predicted length of hospital stay and costs were compared with actual length of stay and costs, using a charge-to-cost conversion formula.

MEASUREMENTS AND MAIN RESULTS

The CABDEAL model was moderately predictive of outcomes. The specificity was 64%, the sensitivity was 73.8%, and the receiver operating characteristic curve area was 0.728. Morbidity in the form of postoperative complications was recorded in 24.5% (3,770 patients), and the mortality rate was 3.4% (527 patients). The mean (+/- SD) total hospital cost was 28,408 US dollars +/-28,982, and the median cost was 21,644 US dollars. Based on the linear regression model, an equation was developed for predicting total costs: Cost (in US dollars) = 22,952 + (3,277. [CABDEAL score]).

CONCLUSION

The previously developed CABDEAL model was predictive of increased morbidity in the SPARCS database. Total hospital costs increased nearly linearly with increasing CABDEAL score. These results encourage the development of models for preoperative estimation of costs related to perioperative morbidity.

Development of C-reactive protein and fibronectin levels in coronary surgery patients: a comparison of on-pump, off-pump sternotomy and off-pump left anterior small thoracotomy groups

In this prospective study, we monitored two laboratory parameters, C-reactive protein (CRP) and fibronectin (FIN) levels, in 30 patients undergoing elective surgery for ischemic heart disease. These patients were divided into three groups according to the surgical procedure used: group A, approach through a median sternotomy with the use of extracorporeal circulation; group B, approach through a median sternotomy without the use of extracorporeal circulation; and group C, approach through a left anterior small thoracotomy (LAST) without the use of extracorporeal circulation. Peak CRP levels were found in all three groups on the second postoperative day, with the mean levels being statistically significantly higher in group C. This group also showed the highest mean CRP levels on the third and fourth postoperative days, with the difference being statistically nonsignificant. These findings can be explained by an enhanced production of cytokines, which in turn trigger CRP synthesis, induced by postoperative pain due to the LAST procedure. No statistically significant correlation between preoperative CRP levels and their postoperative development was found. None of the groups studied showed any statistically significant decrease in FIN plasma levels, either prior to adjustment for hemodilution or after adjustment for hematocrit and serum albumin.

Coronary end-to-side sleeve anastomosis using adhesive in off-pump bypass grafting in the pig

BACKGROUND

In the exploration of facilitated coronary anastomosis strategies, we assessed a new octylcyanoacrylate adhesive in combination with a modified end-to-side sleeve anastomosis in off-pump bypass grafting in the pig.

METHODS

Sleeve-adhesive anastomoses (n = 20) were evaluated intraoperatively, at 3 days (n = 4), and at 5 weeks (n = 16) in an off-pump, low (< or = 15 mL/min; n = 10) and high flow (approximately 60 mL/min; n = 10) porcine bypass model. All anastomoses were examined by flow measurement, angiography, and histology.

RESULTS

Anastomosis construction took 8.5 minutes (6.7 to 10.2 minutes; median [15th to 85th percentile]). At 5 weeks, all anastomoses were fully patent (FitzGibbon grade A). The adhesive did not cause impaired vessel wall healing, but was surrounded by a focal acute and limited chronic (foreign body giant cells occasionally seen) inflammatory reaction at the adventitial application site.

CONCLUSIONS

Octyl-cyanoacrylate tissue adhesive combined with end-to-side internal mammary to coronary artery sleeve anastomosis construction proved to be feasible, even in low bypass graft flow conditions (< or = 15 mL/min; prothrombotic milieu) in the pig and deserves interest in exploration of facilitated anastomosis strategies in coronary artery bypass grafting.

Unconventional vessel wall apposition in off-pump porcine coronary artery bypass grafting: low versus high graft flow

OBJECTIVE

Facilitated coronary anastomosis techniques may involve unconventional vessel wall apposition in contrast to standard intima-intima apposition. We assessed the patency, anastomotic thrombus formation, and intimal hyperplasia of unconventional intima-adventitia apposition versus conventional suturing techniques in beating heart coronary bypass grafting under low versus high graft flow conditions.

METHODS

The intima-adventitia (n = 28) and conventional anastomoses (n = 28) were evaluated intraoperatively (n = 56), at 4 hours (n = 20), and at 5 weeks (n = 36) in a new off-pump low-flow (n = 28) and high-flow (n = 28) porcine bypass model (< or = 15 mL/min and about 60 mL/min, respectively). The anastomoses were assigned to the animals by means of randomized stratification and examined by means of flow measurements, angiography, and histology.

RESULTS

Mean graft flows in intima-adventitia and in conventional anastomoses were similar (P =.709). All but 1 of 56 anastomoses (low flow conventional) were fully patent at the time of death. At 4 hours, only small platelet depositions were found at the exposed media and adventitia in the unconventional anastomoses. At 5 weeks, little streamlining intimal hyperplasia was found, which was comparable between the anastomoses (P =.600).

CONCLUSIONS

In low-flow conditions (< or = 15 mL/min) unconventional intima-adventitia apposition was not detrimental to the internal thoracic-coronary artery anastomosis in the pig. This finding may expand design strategies of facilitated coronary artery bypass anastomosis techniques.

Further reduction in stroke after off-pump coronary artery bypass grafting: a 10-year experience

BACKGROUND

Perioperative stroke is a devastating complication after coronary artery bypass grafting (CABG). The reported incidence of neurologic complications after conventional CABG is 3% to 7%. With improved monitoring and surgical techniques, we have been able to achieve a drastic reduction in the stroke rate in our institution. This study evaluates the incidence of neurologic sequelae in patients who underwent off-pump CABG.

METHODS

Over a 10-year period from January 1990 to September 2000, off-pump coronary artery bypass (OPCAB) operation was performed on 2,800 patients of the 18,037 patients undergoing CABG during that time frame at the Escorts Heart Institute and Research Centre. Initially, OPCAB was performed selectively in the high-risk group of patients (atheromatous aorta, renal impairment, chronic obstructive pulmonary disease, octogenarians, etc). Lately we performed multivessel OPCABs electively in about 60% to 65% of the patients undergoing CABG. Results. Mean age of the patients was 58.0 +/- 9.91 years (range 27 to 85 years) and mean number of grafts was 2.9 per patient. Neurologic complications (stroke/transient ischemic attack) occurred in 0.14% of patients. Overall hospital mortality in OPCAB patients was 2.14%, whereas mortality from neurologic complications was 0.07%. Predicted mortality (National Society of Thoracic Surgeons Cardiac Surgery Database Risk Model for CABG) for the entire patient group was 3.86% (p < 0.001). Conclusions. Although current techniques of monitoring and surgical procedures have significantly reduced the risk of stroke from CABG, our data strongly support OPCAB as a technique to further reduce stroke after CABG, especially in the high-risk group of patients.

Prospective clinical trial of robotically assisted endoscopic coronary grafting with 1-year follow-up

OBJECTIVE

To follow up in prospective fashion patients with coronary artery anastomoses completed endoscopically with robotic assistance. The robotic system was evaluated for safety and its effectiveness in completing microsurgical coronary anastomoses.

SUMMARY BACKGROUND DATA

Recently there has been an interest in using robotics and computers to enhance the surgeon's ability to perform endoscopic cardiac surgery. This interest has stemmed from the rapid advancement of technology and the desire to make cardiac surgery less invasive. Using traditional endoscopic instruments, it has not been possible to perform coronary surgery.

METHODS

Nineteen patients underwent robotically assisted endoscopic coronary artery bypass grafting of the left internal thoracic artery (LITA) to the left anterior descending artery (LAD). Two robotic instruments and one endoscopic camera were placed through three 5-mm ports. A robotic system was used to construct the LITA-LAD anastomosis. All other required grafts were completed by conventional techniques.

RESULTS

Seventeen LITA-LAD grafts (89%) had adequate intraoperative flow. The mean LITA-LAD graft flow was 38.5 +/- 5 mL/min. At 8 weeks, LITA-LAD grafts were assessed by angiography and showed 100% patency with thrombolysis in myocardial infarction (TIMI) I flow. At a mean follow-up of 17 +/- 4.2 months, all patients were NYHA class I and there were no adverse cardiac events.

CONCLUSIONS

The results from the first prospective clinical trial of robotically assisted endoscopic coronary bypass surgery in the United States showed favorable short-term outcomes with no adverse events. Robotic assistance is an enabling technology allowing the performance of endoscopic coronary anastomoses.

Off-pump coronary operations can be safely taught to cardiothoracic trainees

BACKGROUND

Off-pump coronary artery bypass (OPCAB) operations are evolving rapidly and becoming established in many cardiothoracic centers. For the technique to be widely applicable, teaching methods must be developed for surgical trainees. Early and midterm clinical outcomes of OPCAB performed at our institution by trainees as first operators under supervision were compared to those obtained in patients operated on by consultants.

METHODS

Analysis was undertaken on data prospectively inserted in the Patient Analysis & Tracking System. Of the 559 OPCAB operations performed between January 1997 and May 2000, 124 (22%) were carried out by a supervised trainee and 435 (78%) by a consultant.

RESULTS

There was no difference in age, sex, angina class, New York Heart Association functional class, or operative priority and extent of coronary artery disease in the two groups. More patients operated on by consultants had a history of congestive heart failure requiring medical therapy, significantly lower ejection fraction, and higher Parsonnet score compared with patients operated on by trainees. Early and midterm clinical results, in terms of morbidity and mortality, were similar in patients operated on by trainees or by consultants.

CONCLUSIONS

Our data show no differences in early and midterm clinical outcome for patients undergoing OPCAB operations performed either by consultants or by trainees under supervision. The improvements in exposure and stabilization techniques, as well as the use of intracoronary shunts, have made it possible and safe to teach trainees off-pump multivessel coronary artery revascularization.

Coronary artery bypass grafting with cardiopulmonary bypass is safe and contributes to favorable long-term results

The aim of this study was to determine the indication for minimally invasive direct coronary artery surgery based on the operative and long-term results of conventional coronary artery bypass grafting with cardiopulmonary bypass. Operative results: The subjects included 505 patients who underwent isolated elective coronary artery bypass grafting with cardiopulmonary bypass from January 1995 through August 1999. The mean age at the time of surgery was 61.9 and the mean number of grafts per patient was 2.6. Long-term results: From January 1984 to December 1995, a total of 907 patients received coronary artery bypass grafting with cardiopulmonary bypass using the internal thoracic artery to the left anterior descending artery with or without saphenous vein grafts to other coronary arteries. The rates of complete and incomplete revascularization were 69.3% (n = 629) and 30.7% (n = 278), respectively. Mean follow-up was 5.95+/-3.0 years. The operative results revealed low output syndrome occurred in 14 patients (2.8%), perioperative myocardial infarction with the appearance of new Q-waves in 5 (1.0%), renal failure requiring transient dialysis in 16 (3.2%), stroke with persistent sequelae in 5 (1.0%), and mediastinitis in 5 (1.0%). Two patients (0.4%) died in the hospital. The long-term results for the 907 patients revealed the 10-year actuarial survival, 10-year cardiac death free, and 10-year cardiac event free rates were 85.7%, 94.1%, and 77.3%, respectively. The 10-year survival rates was 88.4% among patients receiving complete revascularization and 79.3% among those receiving incomplete revascularization (p = 0.0334). The 10-year cardiac death free rate among patients undergoing complete revascularization was 96.3% and 88.7% among those receiving incomplete revascularization (p = 0.0016). The 10-year cardiac event free rates were 82.3% and 67.9%) among patients undergoing complete and incomplete revascularization, respectively (p = 0.0118). In view of the favorable operative and long-term results of conventional coronary artery bypass grafting, especially complete revascularization, we conclude that minimally invasive direct coronary artery grafting is an appropriate treatment for multi-vessel disease in carefully selected patients at a high risk for stroke and major comorbidities due to old age.

Arteriotomy closure by glued patch in the porcine carotid artery

BACKGROUND

A thoracoscopic approach to coronary bypass grafting warrants renewed search for facilitated vascular anastomosis methods. We reassessed tissue adhesion, sealing properties, and histotoxicity of iso-butyl-cyanoacrylate, in a simplified anastomosis model.

METHODS

In 12 Dutch landrace pigs, five arteriotomies were made in each carotid artery. The arteriotomies were closed by conventional microvascular suturing or by pericardial patch (Peri-Strips) and iso-butyl-cyanoacrylate. The animals were sacrificed at 2 hours (n = 2), 2 days (n = 5), and 4 weeks (n = 5). The arteries were examined by flow measurement, angiography, and histologic analysis.

RESULTS

The time required to close arteriotomies by conventional suturing was 257 +/- 43 seconds (mean +/- SD) and by glued patch 51 +/- 27 seconds (p < 0.001). In all arteriotomies covered by glued patch, complete hemostasis was obtained. At 2 days and 4 weeks, with both methods the same histologic results were observed. At follow-up, all carotid arteries were patent without stenoses.

CONCLUSIONS

Arteriotomy closure by glued patch was simple, fast, reliable, and without signs of histotoxicity. Adhesives deserve to be reconsidered as an alternative to suturing in closed chest beating-heart coronary surgery.

Coronary artery bypass grafting on the beating heart evaluated with integrated backscatter

BACKGROUND

In beating heart coronary artery bypass grafting (CABG) the effect of ischemic insult during coronary occlusion could not be evaluated immediately. Using transesophageal echocardiography, myocardial performance can be evaluated with analysis of integrated backscatter.

METHODS

In 15 beating heart CABGs, cyclic variation (CV) of integrated backscatter of the anterior wall before, during, and after the left internal thoracic artery to left anterior descending (LAD) branch anastomosis was measured with transesophageal echocardiography. The patients were divided into two groups according to collateral vessels status (good collateral group n = 6, poor collateral group n = 9).

RESULTS

In all patients, CV increased significantly after revascularization (8.56+/-2.50 to 11.47+/-3.32 dB, p < 0.0001). During LAD occlusion, significant decrease in CV was found in patients who had poor collateral arteries. At 15 minutes of LAD occlusion, CV decreased from the preocclusion value of 7.51+/-2.21 to 3.23+/-4.03 dB (p < 0.01).

CONCLUSIONS

Measurement of CV can detect the ischemic insult during coronary occlusion and the effect of revascularization in beating heart CABG.

Assessment of patented coronary end-to-side anastomotic devices using micromechanical bonding

BACKGROUND

Despite multiple patented ideas for vascular end-to-side anastomotic devices, and the growing need for them in minimally invasive coronary bypass procedures, no device has been evaluated clinically yet. This study assessed patents of micromechanical end-to-side anastomotic devices with respect to application in coronary artery bypass grafting.

METHODS

Patents were categorized with respect to their micromechanical bonding principle. Calculated values for the wall strain during the construction of an anastomosis were compared with the allowable strain for human coronary arteries.

RESULTS

From 51 patents describing vascular anastomotic devices, 11 ideas, categorized into four groups (staples, clips, mounting systems, and intraluminal stent structures), are serious candidates for coronary end-to-side anastomoses. Most ideas use an anvil for proper application of the bonding elements. For small (1.5 mm) coronary arteries, the calculated wall strain was 0.87, exceeding the breaking strain (0.45) in 60- to 79-year-old patients.

CONCLUSIONS

In a coronary anastomotic device, the concept of using an anvil for the application of micromechanical bonding elements is not attractive, because excessive wall strain is likely to occur.

Exposure of circumflex branches in the tilted, beating porcine heart: echocardiographic evidence of right ventricular deformation and the effect of right or left heart bypass

OBJECTIVE

In off-pump coronary surgery, exposure of posterior vessels via sternotomy causes deterioration of cardiac function. Changes in ventricular geometry, valve competence, and hemodynamics after retraction of the beating heart were studied. Subsequently, the modifying effect of right or left heart bypass was investigated.

METHODS

In six 80-kg pigs, an ultrasound probe was attached to the backside of the left ventricle and the heart was fully retracted with a suction tissue stabilizer. Five pigs underwent additional pump support.

RESULTS

During retraction, the right ventricle was squeezed between the pericardium and interventricular septum, thereby decreasing its diastolic cross-sectional area by 62% +/- 6% (P <.001) while, concomitantly, right ventricular end-diastolic pressure increased to 165% +/- 19% (P =.004) of basal values. Stroke volume and mean arterial pressure decreased by 29% +/- 6% and 23% +/- 8% (P =.007 and P =.02, respectively). Left ventricular shape became somewhat elliptic without changes in preload pressure, and its diastolic cross-sectional area decreased by 20% +/- 3% (P =.001). All valves were competent. Right heart bypass restored left ventricular cross-sectional area, stroke volume, and mean arterial pressure. In contrast, left heart bypass increased blood pressure only marginally.

CONCLUSIONS

Ninety-degree anterior displacement of the beating porcine heart caused primarily right ventricular dysfunction as a result of mechanical interference with diastolic expansion without concurring valvular incompetence. Right heart bypass normalized stroke volume and mean arterial pressure by increasing left ventricular preload; in contrast, left heart bypass failed to restore systemic circulation.