Conversion during off-pump coronary artery bypass graft surgery: A case–control study

Objectives: Off pump coronary artery bypass (OPCAB) surgery is carried out as an alternative to conventional coronary artery bypass grafting using cardiopulmonary bypass (CPB). At times 'conversion' to CPB may be required to bail out a situation resulting from acute decompensation of the heart. It is reported that such conversion carries significant mortality risk. Since we conduct coronary revascularization by OPCAB technique as the preferred technique, we conducted this study with an aim to identify the markers of adverse outcome during conversion in Indian patients. Design: Case control retrospective study. Setting: Tertiary referral center. Participants: We conducted three thousand two hundred OPAB surgeries in the period between 2013 to16. Ninety patients (3.1%) required conversion to complete the revascularization (Con version group). Twice the number of patients who underwent OPCAB surgery without conver sion were chosen as controls (Control group). Intervention: OPCAB surgery Results: Mortality in the conversion group was 5.56% in contrast to 0.06% in the controls (P = 0.01). The conversion group had higher left ventricular end diastolic pressure, incidence of endarterectomy, and intra-aortic balloon counter pulsation requirement. Female gender was also predictive of conversion. The total chest drain, duration of ventilation, ICU stay and hospital stay were also higher in the conversion group. Conversion was associated with 9.47 times the odds for mortality. Conclusion: Conversion during OPCAB is associated with significantly increased mortality. Female gender, increased left ventricular end diastolic pressure and preoperative requirement of Intra-aortic balloon are markers of increased risk of mortality when converted.

Anesthetic implications of subxiphoid coronary artery bypass surgery.

Background: Minimal invasive surgeries are carried out to benefit the patient with less pain, blood loss, mechanical ventilation and hospital stay; a smaller scar is not the aim. Minimal invasive cardiac surgeries are carried out via small sternotomy, small thoracotomy and via robotic arms. Subxiphoid route is a novel method and avoids sternotomy. Aim: This case series is an attempt to understand the anesthetic modifications required. Secondly, whether it is feasible to carry out subxiphoid coronary artery bypass surgery. Methods: Elective patients scheduled to undergo subxiphoid coronary artery bypass surgery were chosen. The surgeries were conducted under general anesthesia with left lung isolation via either endobronchial tube or bronchial blocker. Results: We conducted ten (seven males and 3 females) coronary artery bypass graft surgeries via subxiphoid technique. The mean EuroSCORE was 1.7 and the mean ejection fraction was 53.6. Eight patients underwent surgery via endobronchial tube, while, in the remaining two lung isolation was obtained using bronchial blocker. Mean blood loss intraoperatively was 300 ± 42 ml and postoperatively 2000 ± 95 ml. The pain score on the postoperative day ‘0’ was 4.3 ± 0.6 and 2.3 ± 0.7 on the day of discharge. Length of stay in the hospital was 4.8 ± 0.9 days. There were no complications, blood transfusions, conversion to cardiopulmonary bypass. The modifications in the anesthetic and surgical techniques are, use of left lung isolation using either endobronchial tube or bronchial blocker, increased duration for conduit harvesting, grafting, requirement of transesophageal echocardiography monitoring in addition to hemodynamic monitoring. Other minor requirements are transcutaneous pacing and defibrillator pads, a wedge under the chest to ‘lift’ up the chest, sparing right femoral artery and vein (to serve as vascular access) for an unlikely event of conversion to cardiopulmonary bypass. Any anesthesiologist wishing to start this technique must be aware of these modifications. Conclusions: Subxiphoid route is safe to carry out coronary artery bypass graft surgery using the minimal invasive cardiac surgery. It is reproducible and has undeniable benefits. We plan to conduct such surgeries in awake patients under thoracic epidural anesthesia thus making it even less invasive and amenable for fast tracking.

Aortic root to left-atrial fistula after aortic valve replacement: A rare complication and its intraoperative management.

Aorto‑atrial fistula is a rare complication of prosthetic aortic valve replacement (AVR) and most of them have been diagnosed as a late complication. We present a case of this unusual complication after AVR. Intraoperative transoesophageal echocardiography identified and diagnosed this rare and potentially disastrous surgical complication and confirmed adequacy of its surgical repair.

Effect of thoracic epidural anesthesia on oxygen delivery and utilization in cardiac surgical patients scheduled to undergo off-pump coronary artery bypass surgery: A prospective study.

To evaluate the effect of thoracic epidural anesthesia (TEA) on tissue oxygen delivery and utilization in patients undergoing cardiac surgery. This prospective observational study was conducted in a tertiary referral heart hospital. A total of 25 patients undergoing elective off-pump coronary artery bypass surgery were enrolled in this study. All patients received thoracic epidural catheter in the most prominent inter-vertebral space between C7 and T3 on the day before operation. On the day of surgery, an arterial catheter and Swan Ganz catheter (capable of measuring cardiac index) was inserted. After administering full dose of local anesthetic in the epidural space, serial hemodynamic and oxygen transport parameters were measured for 30 minute prior to administration of general anesthesia, with which the study was culminated. A significant decrease in oxygen delivery index with insignificant changes in oxygen extraction and consumption indices was observed. We conclude that TEA does not affect tissue oxygenation despite a decrease in arterial pressures and cardiac output.

Intra-aortic balloon pump use does not affect the renal function in patients undergoing off pump coronary artery bypass surgery.

Renal dysfunction is known to occur during cardiac surgery. A few factors such as perioperative hypotension, use of potential nephrotoxic therapeutic agents, radio opaque contrast media in the recent past, intra-aortic balloon pump (IABP) and cardiopulmonary bypass have been blamed as the contributing factors to the causation of postoperative renal dysfunction in cardiac surgical patients. At times, in patients with renal failure and low cardiac output status, one may face the dilemma if the use of IABP is safe. We undertook this prospective observational study to determine the degree of possible renal injury when IABP is used by measuring serial values of serum creatinine and Cystatin C. Elective patients scheduled for off-pump coronary artery bypass surgery requiring preoperative use of IABP were included in this study. Cystatin C and serum creatinine levels were checked at fixed intervals after institution of IABP. Twenty-two patients were eligible for enrolment to the study. There was no significant change in the values of serum creatinine; from the basal value of 1.10 ± 0.233 to 0.98 ± 0.363 mg /dL (P value >0.05). Cystatin C levels significantly decreased from the basal level of 0.98 ± 0.29 to 0.89 ± 0.23 (P value <0.05). Contrary to the belief, Cystatin C, the early indicator of renal dysfunction decreases suggesting absence of renal injury after the use of IABP. Absence of elevation of cystatin C levels in our study suggests the lack of potential of the IABP to cause renal dysfunction in patients who received elective IABP therapy preoperatively.

Use of intraaortic balloon counter pulsation in a patient with tortuous aorta.

The intraaortic balloon pulsation (IABP) catheter is commonly used to treat left ventricular failure. The abnormality of the descending thoracic and abdominal aorta is considered as a relative contraindication for its insertion. We present here a patient with acute myocardial infarction with a post-infarct ventricular septal defect who presented with left ventricular failure. During coronary angiography, tortuous abdominal aorta was noted and IABP catheter was inserted under fluoroscopic guidance to support the cardiovascular system. This case is reported to encourage discussion on the use of IABP catheters in patients with tortuous aorta and avoidance of events described.

Comparison of simultaneous estimation of cardiac output by four techniques in patients undergoing off-pump coronary artery bypass surgery--a prospective observational study.

We prospectively compared four techniques of cardiac output measurement: bolus thermodilution cardiac output (TDCO), continuous cardiac output (CCO), pulse contour cardiac output (PiCCO), and Flowtrac (FCCO), simultaneously in fifteen patients undergoing off-pump coronary artery bypass grafting (OPCAB). All the patients received pulmonary artery catheter (capable of measuring both bolus thermodilution cardiac output and CCO), PiCCO arterial cannula in the left and FCCO in the right femoral artery. Cardiac indices (CI) were obtained every fifteen minutes by using all the four techniques. TDCO was treated as 'control' and the rest were treated as 'test' values. Interchangeability of techniques with TDCO was assessed by Bland and Altman plotting and mountain plot. Four hundred and thirty eight sets of data were obtained from fifteen patients. The values of cardiac output varied between 1 to 6.9 L/min. We found that the values of all the techniques were interchangeable. At certain times, the values of CI measured by both PiCCO and FCCO appeared erratic. The values of CI measured simultaneously appeared in the following descending order of accuracy; TDCO>CCO>FCCO>PiCCO (the % times TDCO correlated with CCO, FCCO, PiCCO was 93, 86 and 80 respectively). The bias and precision (in L/min) for CCO were 0.03, 0.06, PiCCO 0.13, 0.1 and flowtrac 0.15, 0.04 respectively suggesting interchangeability. We conclude that the cardiac output measured by CCO technique and the pulse contour as measured by PiCCO and FCCO were interchangeable with TDCO more than 80% of the times.

Conscious off-pump coronary artery bypass surgery.

BACKGROUND: Cardiothoracic surgery has been previously performed successfully under thoracic epidural anesthesia alone. Between October 2001 and December 2003, we performed 123 conscious off-pump coronary artery bypass surgeries using epidural anesthesia as the sole anesthetic. This technique is an alternative to cardiothoracic surgery performed under general anesthesia. Certain modifications in the technique facilitate the process. METHODS AND RESULTS: There were 24 female patients and 99 male patients with mean age of 58.6 +/- 6.2 years; 12 patients underwent repeat coronary artery bypass surgery. All the patients underwent epidural catheterization on the evening before surgery. Out of the 123 patients scheduled for coronary artery bypass graft surgery, 120 underwent off-pump coronary artery bypass graft surgery successfully; 4 patients underwent off-pump surgery via left thoracotomy and the rest through mid sternotomy. These patients received 295 grafts in all (single graft in 26 patients, double in 42 patients, triple in 35 patients, and quadruple in 20 patients). Three patients required conversion to general anesthesia and one to cardiopulmonary bypass. There was no mortality in the group. CONCLUSIONS: Our experience suggests that by modifying the surgical techniques, we can accomplish conscious coronary artery bypass surgery.