Intraoperative Transesophagial Echocardiography Modifies Strategy in Off-Pump Coronary Artery Bypass Grafting

Intraoperative echocardiographic coronary artery imaging in congenital and acquired heart disease

Transoesophageal and epicardial echocardiography are indispensible intraoperative imaging modalities to guide paediatric heart disease surgeries and influence surgical decision-making. A less well-described role of intraoperative imaging is its utility in evaluating coronary artery patency and flow. Focused two-dimensional, colour, and spectral Doppler imaging of the coronary arteries should be performed during surgeries involving coronary manipulation or re-implantation, or in cases where there is unexpected ventricular dysfunction or electrographic signs concerning for ischaemia. Intraoperative imaging allows for any anatomical issues to be detected and addressed promptly in the operating room. Imaging of the coronary arteries should identify unobstructed coronary ostia and proximal course without kinking, angulation, narrowing, or significant calibre change to suggest stenosis or extrinsic compression from neighbouring structures. The aim of this review is to highlight the usefulness of transoesophageal and epicardial echocardiography in evaluating coronary artery patency and flow, provide a how-to guide for optimal imaging, and to introduce a practical guideline to achieve best clinical practice.

Monitoring diastolic dysfunction using a simplified algorithm in patients undergoing off-pump coronary artery bypass grafting surgery

Context:

Left ventricle diastolic dysfunction (LVDD) is gaining importance as useful marker of mortality and morbidity in cardiac surgical patients. Different algorithms have been proposed for the intraoperative grading of DD. Knowledge of the particular grade of DD has clinical implications with the potential to modify therapy, but there is a paucity of literature on the role of diastolic function evaluation during off-pump coronary artery bypass grafting (OPCABG) surgery.

Aims:

The aim of this study was to monitor changes in LVDD using simplified algorithm proposed by Swaminathan et al. in patients undergoing OPCABG.

Settings and Design:

The study was conducted in a tertiary care level hospital; this was a prospective, observational study.

Subjects and Methods:

Fifty consecutive patients undergoing OPCABG were enrolled. Hemodynamic and echocardiographic parameters were measured at 6 stages in every patient namely after anesthetic induction (baseline), during left internal mammary artery (LIMA) to left anterior descending (LAD) grafting (LIMA → LAD), saphenous vein graft (SVG) to obtuse marginal (OM) grafting (SVG → OM), SVG to posterior descending artery (PDA) grafting (SVG → PDA), during proximal anastomosis of SVG to aorta, and postprotamine. The patients were classified in grades of LVDD as per simplified algorithm proposed by Swaminathan et al. using only intraoperatively measured E and E’.

Results:

The success rate of measurement and classification of LVDD was 98.92% (277 out of 280 measurements). The grades of LVDD varied significantly as per surgical steps with maximum downgrading occurring during OM and LAD grafting. During OM grafting, none of the patients had normal diastolic function while 29% of patients exhibited restrictive pattern (Grade 3 LVDD). Patients with normal baseline LV diastolic function also exhibited downgrading during OM and LAD grafting. Postprotamine, 37% of patients with normal baseline diastolic function continued to exhibit some degree of DD.

Conclusions:

The LVDD changes dynamically during various stages of OPCABG, which can be successfully monitored with simplified algorithm.

Effect of on-pump versus off-pump coronary bypass surgery on cardiac function assessed by intraoperative transesophageal echocardiography

PURPOSE

To compare cardiac function assessed by intraoperative transesophageal echocardiography in patients undergoing cardiac revascularization with or without cardiopulmonary bypass.

MATERIAL AND METHODS

Forty-one patients scheduled for elective, isolated cardiac revascularization (21 on-pump and 20 off-pump) were prospectively analyzed. Patients were matched for demographic (age and gender), anthropometric (BMI), clinical (co-morbidities, EuroScore) and laboratory variables (blood counts, renal function, left ventricular function). Transesophageal echocardiography was performed after induction of anesthesia, protamine sulfate administration, and chest closure. Left ventricular wall motion score index, end-diastolic area, fractional area change, right ventricular area change and end-diastolic area were assessed. Troponin I and C-reactive protein concentrations were measured.

RESULTS

Regarding echocardiographic parameters of left and right ventricular function no significant differences between on-pump and off-pump groups at any point-of-time measurements were found. Troponin I and C-reactive protein were higher in on-pump as compared to off-pump group (p=0.001 and p=0.002; p=0.003 and p=0.001, respectively).

CONCLUSIONS

In elective patients scheduled for cardiac revascularization there were no difference in cardiac performance assessed by intraoperative echocardiography regardless of surgical method used.

Deep Pericardial Traction Suture versus Vacuum-Assisted Apical Suction to Expose the Posterior Wall of the Heart in Off-Pump Coronary Artery Bypass: A Prospective, Randomized Study

<p><b>Background:</b> Displacement of the heart to expose the posterior vessels during off-pump coronary artery bypass (OPCAB) may cause hemodynamic instability. Deep pericardial traction suture (DPTS) and vacuum-assisted apical suction (VAS) with the Starfish positioning device help to provide good exposure without relevant hemodynamic changes. Our aim was to compare these two methods in patients undergoing multivessel OPCAB.</p><p><b>Methods:</b> We prospectively randomized 20 patients undergoing multivessel OPCAB to the use of VAS or DPTS. The Octopus device was used in both groups to stabilize the target vessel. Hemodynamic parameters, including venous oxygen content (SvO₂₎, cardiac index (CI), central venous pressure (CVP), mean arterial pressure (MAP), pulmonary artery pressure (PAP), and pulmonary capillary wedge pressure (PCWP), were measured before grafting (baseline), after heart positioning, and during performance of peripheral anastomoses.</p><p><b>Results:</b> Perioperative data for the two groups were similar. During exposure of the lateral wall, there were fewer hemodynamic changes in the DPTS group (increase in CVP) than in the VAS group (increases in CVP, PAP, and PCWP); the CVP was significantly higher in the DPTS group (<i>P</i> < .05). During exposure of the posterior wall, significant hemodynamic changes occurred only in the DPTS group (increase in PCWP). Values for all other parameters were similar, including anastomosis time, graft flow, postoperative myocardial enzymes, and inotropic support.</p><p><b>Conclusions:</b> Heart positioning during OPCAB with either VAS or DPTS is a safe and effective maneuver for exposure of coronary arteries. In our study, the use of the VAS device produced less hemodynamic impairment during exposure of the lateral and posterior walls.</p>

In vivo detection of myocardial ischemia in pigs using visible light spectroscopy

BACKGROUND

Monitoring tissue oxygenation (StO(2)) by visible light spectroscopy (VLS) can identify tissue ischemia, but its feasibility for detecting myocardial ischemia is not known. We hypothesized that VLS can reliably detect changes in myocardial StO(2) in pigs subjected to acute regional or global myocardial ischemia.

METHODS

In 11 pigs, regional myocardial ischemia was created by ligation of left anterior descending artery (LAD). Myocardial StO(2) was determined from the ischemic and nonischemic left ventricular (LV) regions and compared to coronary venous saturations. Myocardial function was assessed by echocardiography. In six pigs, LV-StO(2) was measured during cardiopulmonary bypass (CPB), after cardioplegic cardiac arrest, and during CPB with inadequate myocardial protection. Additionally, right ventricular (RV)- and LV-StO(2) were assessed during acute RV pressure overload from pulmonary artery (PA) banding.

RESULTS

StO(2) baselines in pigs undergoing LAD occlusion were similar in the ischemic and nonischemic myocardium (70% +/- 8% vs 74% +/- 5%). After LAD ligation, StO(2) rapidly declined (30 s: 59% +/- 8%; 1 min:50 +/- 9; 5 min:42% +/- 4%; P < 0.05) in the ischemic myocardium. Decreases in StO(2) correlated with coronary venous saturations (r = 0.88) and were associated with myocardial dysfunction. In pigs undergoing CPB, LV-StO(2) remained unchanged with initiation of CPB or after cardioplegic cardiac arrest, but LV ischemia was detected by StO(2) after aortic cross-clamp without adequate myocardial protection. Similarly, PA banding resulted in a profound decrease of RV-StO(2) from 69% +/- 6% to 52% +/- 7% (P < 0.05) with recovery after PA release.

CONCLUSIONS

VLS is a reliable method of detecting alterations in myocardial StO(2) and can be a useful monitor for rapid identification of myocardial ischemia.

Enhanced intra-operative grading of ascending aorta atheroma by epiaortic ultrasound vs echocardiography

AIMS

Intra-operative grading of atheromatous plaques in the ascending aorta by epiaortic ultrasound (EAU) and transesophageal echocardiography (TEE) in patients who have undergone CABG.

METHODS AND RESULTS

Sixty patients scheduled for elective CABG were prospectively enrolled to undergo intra-operative TEE and EAU ultrasound scanning of the ascending aorta. The ascending aorta was divided into three sections; proximal, middle and distal, and four segments; anterior, posterior, medial and lateral. Degree of atherosclerosis was graded according to a modified Montgomery scale. Epiaortic ultrasound was unable to provide images for a reliable assessment in 56 areas (7.7%; 56/720) vs 322 non-visualized areas by TEE (44.7%; 298/720) (p<0.01). Out of 563 areas that scored >or=2, EAU visualized 379/720 areas (52.6%), whereas TEE visualized 184/720 areas (25.5%) (p<0.01). EAU mean scores were significantly higher for the mid (p=0.0001) and distal (p=0.05) sections and for the posterior segment (p<0.01) vs TEE. TEE had a higher mean score than EAU in the anterior segment. When all EAU areas were grouped the posterior segment reached a significantly higher mean score (p<0.01), and the anterior segment was the second mostly diseased.

CONCLUSIONS

EAU is the intra-operative investigation of choice because it allowed a detailed grading of atheromatous lesions over the entire length of the ascending aorta. Accurate grading by TEE was restricted only to those areas that could be sufficiently visualized. TEE has a reduced power of investigation that limits its use, especially in the distal ascending aorta, a site of great surgical manipulation.