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.

Transesophageal echocardiography evaluation of the thoracic aorta.

Transesophageal echocardiography (TEE) can be used to identify risk factors such as aortic atherosclerosis [2] before any sort of surgical manipulations involving aorta and its related structures. TEE has become an important noninvasive tool to diagnose acute thoracic aortic pathologies. TEE evaluation of endoleaks helps early detection and immediate corrective interventions. TEE is an invaluable imaging modality in the management of aortic pathology. TEE has to a large extent improved the patient outcomes.

Cardiopulmonary bypass in conscious patients undergoing cardiac surgery.

This study was undertaken to evaluate the feasibility of thoracic epidural anesthesia as an alternative technique to general anesthesia in patients undergoing cardiac surgery under cardiopulmonary bypass. This prospective study was conducted in a tertiary referral hospital. Seventeen patients underwent cardiac surgical procedures requiring cardiopulmonary bypass without general anesthesia under thoracic epidural anesthesia from February to May 2004. An epidural catheter was inserted at any of intervertebral spaces from C7 to T2 on the day before surgery. Subsequently, cardiac surgery was performed under normothermic cardiopulmonary bypass, during which the patients remained conscious. The types of surgery included closure of atrial septal defects, valve replacements, and combined bypass surgery and valve replacements. Approach to the heart was obtained through midsternotomy. Anticoagulation was achieved with 300 units/kg of heparin. Normothermic cardiopulmonary bypass was initiated slowly during the course of 10 to 15 min. Nonpulsatile flow was administered using centrifugal pump and mean perfusion pressure was maintained in the range of 70-80 mmHg. The planned surgical procedure could be performed in all the patients. Soon after establishing cardiopulmonary bypass, the patients developed apnea, which reverted to normalcy a few minutes after disconnection of cardiopulmonary bypass. The mean time for cardiopulmonary bypass was 102 +/- 28 min, aortic cross clamp time was 58 +/- 28 min, and the total duration of surgery was 229 +/- 64 min. None of the patients required conversion to general anesthesia. There was no mortality or morbidity in this series and to our knowledge our series is the first such. Cardiac surgical procedures requiring cardiopulmonary bypass may be conducted under thoracic epidural anesthesia, without endotracheal general anesthesia.

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.

Transesophageal echocardiography estimation of coronary sinus blood flow for the adequacy of revascularization in patients undergoing off-pump coronary artery bypass graft.

AIMS AND OBJECTIVES: Physiologically coronary sinus (CS) drains the left coronary artery (LCA) territory. Stenosis of the branches of LCA may decrease the coronary sinus blood flow (CSBF). Any intervention that aims at restoring the flow of the stenosed vessel increases coronary artery flow that should consequently increase the CSBF. Hence, this study was undertaken to assess the CSBF before and after each branch of LCA to determine the adequacy of surgical revascularization in patients undergoing elective off pump coronary artery bypass grafting (OPCAB) using transesophageal echocardiography (TEE). MATERIALS AND METHODS: Thirty consecutive patients scheduled for elective OPCAB were enrolled. CSBF was assessed before and after each branch of LCA revascularization using TEE. Left internal mammary artery (LIMA) Doppler was also obtained post LIMA to left anterior descending (LAD) grafting. RESULTS: Hemodynamic and echocardiographic variables were compared by means of Student's t-test for paired data before and after revascularization. The CSBF per beat (1.28 ± 0.71), CSBF per minute (92.59 ± 59.32) and total velocity time integral (VTI) (8.93 ± 4.29) before LAD grafting showed statistically significant increase to CSBF per beat (1.70 ± 0.89), CSBF per minute (130.72 ± 74.22) and total VTI (11.96 ± 5.68) after LAD revascularization. The CSBF per beat (1.67 ± 1.03), CSBF per minute (131.91 ± 86.59) and total VTI (11.00 ± 5.53) before obtuse marginal (OM) grafting showed statistically significant increase to CSBF per beat (1.91 ± 1.03), CSBF per min (155.20 ± 88.70) and total VTI (12.09 ± 5.43) after OM revascularization. In 9 patients, color flow Doppler of LIMA could be demonstrated which showed diastolic predominant blood flow after LIMA to LAD grafting. CONCLUSION: Demonstration of CSBF was simple and monitoring the trend of CSBF values before and after each graft of LCA territory will guide to determine the adequacy of surgical revascularization.

Utility of pulmonary venous flow diastolic deceleration time in an adult patient undergoing surgical closure of atrial septal defect and coronary artery bypass grafting.

Acute left ventricular (LV) failure has been reported after surgical closure of atrial septal defect (ASD) in adult patients. We report acute LV failure in a 56 year old gentleman following coronary artery bypass grafting (CABG) and surgical closure of ASD. Transesophageal echocardiography examination of the patient following closure of ASD and CABG showed a residual ASD and a shunt (Qp :Qs = 1.5). The residual ASD was closed after re-institution of cardiopulmonary bypass (CPB) under cardioplegic cardiac arrest. However, the patient did not tolerate closure of the residual ASD. The CPB was re-established and under cardioplegic cardiac arrest residual ASD was reopened to create a fenestration. This time patient was weaned easily from CPB. Postoperatively, 16 hours after extubation, patient became hemodynamically unstable, the patient was electively put on ventilator and intra-aortic balloon pump. Later the patient was weaned off successfully from ventilator. Retrospective analysis of pulmonary venous flow diastolic deceleration time (PVDT D ) recorded during prebypass period measured 102 msec suggestive of high left atrial pressure which indicate possibility of LV failure after ASD closure.

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.

High thoracic epidural anesthesia as the sole anesthetic for performing multiple grafts in off-pump coronary artery bypass surgery.

OBJECTIVES: The feasibility of the use of high thoracic epidural anesthesia as a sole anesthetic in patients undergoing beating heart coronary revascularization avoiding general anesthesia was studied. DESIGN: A prospective study. SETTING: A tertiary care medical center. INTERVENTIONS: Fifteen patients underwent beating heart coronary artery revascularization without endotracheal general anesthesia, between October 2001 to May 2002, using high thoracic epidural anesthesia and analgesia. All the patients underwent epidural catheterization on the evening before the surgery. MEASUREMENTS AND MAIN RESULTS: The patients received 36 grafts (single, n = 5; double, n = 3; triple, n = 3; quadruple, n = 4). There were 3 female patients and 12 male patients with mean age of 60.6 +/- 5.9 years. Two patients underwent repeat coronary artery bypass. All the patients underwent off-pump coronary artery bypass graft surgery; 2 patients underwent grafting via left thoracotomy and the rest through a midsternotomy. There was no conversion to general anesthesia or cardiopulmonary bypass, and there was no mortality. Mean length of stay in the intensive care unit was 18.2 +/- 4.2 hours and in the hospital was 3.2 +/- 1.2 days. CONCLUSION: Experience confirms the feasibility of performing multiple coronary artery bypasses in conscious patients without endotracheal general anesthesia.

Continuous counter-current two-phase aqueous extraction.

Continuous counter-current column operation provides operating convenience for contacting two-phase aqueous partitioning systems for protein extraction. We discuss in detail the important parameters for designing spray, packed, plate and York-Scheibel columns for protein recovery using both polymer-polymer and polymer-salt two-phase aqueous systems. We compare the various contractors for their operating and extraction efficiency. The work also provides a step-by-step design procedure and specific recommendations for future data needs.