Two decades of off-pump coronary artery bypass surgery: Harefield experience

Cardiac Surgery: Beyond Conventional Sternotomy With Cardiopulmonary Bypass

Minimally invasive cardiac surgery options, which originated with off-pump coronary artery bypass grafting and aortic valve procedures, continue to evolve in order to address complex conditions, including those requiring mitral and tricuspid valve repair. Although these procedures are primarily indicated for high-risk patient populations, favorable patient outcomes have resulted in recommendations being expanded to include intermediate-risk groups. This article increases nursing-related knowledge of minimally invasive cardiac procedures, providing an overview of current minimally invasive cardiac surgeries and their associated risks and benefits.

Conversion from Off to On-Pump Coronary Artery Bypass Grafting. Is it Avoidable?

Background

With the emergence of new technologies to stabilize the heart off-pump coronary artery bypass grafting (OPCAB), there is an increasing trend that is being observed throughout the world. In certain circumstances, OPCAB needs to be converted to on-pump CABG (ONCAB). In this study, we aim to identify certain risk factors mandating conversions and their associated short-term outcomes.

Methods

After approval from the institutional ethical review committee and exemption from informed consent, retrospective data of 100 patients meeting the inclusion criteria who underwent OPCAB operations at our institution from August 2018 to July 2019 were included. Preoperative, intraoperative, and postoperative variables were recorded and compared in conversion and non-conversion groups. This study was conducted at the National Institute of Cardiovascular Diseases, Karachi, Pakistan.

Results

A total of 100 patients were included in this study, out of which 82% (82) were male, with age ranging between 18 and 77 years with a mean age of 56.34 ± 8.3 years. In nine of the cases, OPCAB was emergently converted to ONCAB due to arrhythmias. In nine (9%) cases, off-pump CABG was emergently converted to on-pump CABG (ONCAB). Emergent conversion was due to arrhythmias in five cases, due to hypotension during OM graft in two cases, and due to hypotension during ramus graft for the remaining two cases. The emergent conversion was significantly associated with higher New York Heart Association (NYHA) functional classification and comorbid conditions such as chronic obstructive pulmonary disease (COPD).

Conclusion

Emergency conversion from off-pump to OPCAB is the most catastrophic event causing higher morbidity and mortality. Conversion rate was observed to be 9% with arrhythmias being the common cause and patients with higher NYHA status and COPD at baseline were found to be at increased risk of emergency conversion. Considering our results in patients with diagnosed COPD and higher NYHA status, the decision for off-pump CABG should be wisely taken carefully weighing the risks and benefits.

Effects of EDC-PEI heparinization on allogeneic vascular antigens and inflammation levels via a rat abdominal aorta transplantation model

The objective of this study was to investigate the possibility of increasing the remote patency rate of allogeneic vessel transplantation through studying the effects of N-ethyl-N-(3-dimethylaminopropyl)-carbodiimide and polyethyleneimine (EDC-PEI) heparinization on allogeneic vascular antigens and inflammation levels. Forty rats were randomly divided into the control group, the EDC group, the PEI group and the EDC-PEI group. The rat abdominal aorta was used as the object of study, and the transplanted blood vessels were pretreated with EDC as the water-soluble cross-linking agent and PEI as the heparin-coated carrier. A rat abdominal aorta allogeneic transplantation model was established. Ultrasonic examination was used for observation of patency of proximal and distal anastomosis in each group. The tissue repair after abdominal aorta transplantation in each group was examined by H&E staining. The biomechanics, denaturation temperature and blasting strength of each group were compared. The levels of IL-1, IL-6 and TNF-α in serum of rats were measured by ELISA method, and the expression of MHC-II and α-GAL antigens in blood vessels were detected by immunohistochemistry. There were different degrees of thickening and inflammatory cell aggregation in the abdominal aorta of rats in the control, EDC and PEI groups, but there was no obvious lesion in the EDC-PEI group. Compared with the four groups, the mechanical characteristics of the EDC group decreased significantly, and the stenosis rate of anastomotic stoma in the EDC group was higher than that in the EDC-PEI and PEI groups (P<0.05). The denaturation temperature of the PEI group was lower than that of the EDC and EDC-PEI groups (P<0.05). The mechanical property and vascular bursting strength in the EDC-PEI group were similar to those in the control group. At the same time, it has more significant advantages than the other three groups in removing the vascular antigens MHC-II and α-GAL and reducing the level of inflammatory reaction, thus increasing the remote patency rate of allogeneic vascular transplantation. The inflammatory response and vascular antigenicity after transplantation are effectively reduced via the rat abdominal aorta transplantation model treated with allogeneic EDC-PEI heparinization, which has a higher remote patency rate.