Effect of coronary bypass surgery and valve replacement on left ventricular function: assessment by intraoperative two-dimensional echocardiography

Mitral valve repair is superior to valve replacement for the early preservation of cardiac function: relation of ventricular geometry to function

The immediate effect or mitral valve repair (MVP) or replacement (MVR) on cardiac function was compared in patients with mitral regurgitation in relation to the changes in left ventricular (LV) function and geometry by using intraoperative transesophageal echocardiography in 29 patients with MVP and 21 patients with MVR, before and immediately after cardiopulmonary bypass. The LV volumes, ejection fraction, and long-axis and short-axis lengths and eccentricity index (ratio of long axis to short axis) at end-systole and end-diastole were measured. After both MVP and MVR, there were significant decreases in LV end-diastolic volume (p < 0.0001). However, the ejection fraction did not change after MVP, whereas it decreased after MVR (p < 0.0001). After MVP, there was an increase in eccentricity index at end-systole (p < 0.0001). After MVR, there was no decrease in end-systolic volume, and the eccentricity index was lower than that after MVP (p < 0.0001). The change in LV ejection fraction correlated with the changes in eccentricity index at end-systole (r = 0.55; p < 0.0001) and end-diastole (r = 0.42; p < 0.0003). Immediate intraoperative LV function is preserved after MVP but is depressed after MVR for mitral regurgitation. The changes in ejection fraction correlate with changes in ventricular geometry.

What's new in monitoring the coronary surgery patient?

Monitoring has been extensively reviewed in most textbooks of cardiothoracic surgery and anaesthesia, particularly in the recent textbooks on monitoring edited by Carol L Lake 1 and Casey D Blitt 2 and in the Journal of Clinical Monitoring. Although monitoring properly includes both pre- and postoperative periods, this review will concentrate exclusively on the operative period. I will also concentrate on new approaches or information which relate to more traditional approaches to monitoring. The emphasis in this review will not be on what we can monitor, but rather on what we should monitor. In this regard, I will analyse accuracy and identify sources of error and try to answer the following questions. Does the device or parameter measure (monitor) what we want to know? Does it improve patient outcome and safety? Is it cost-effective? Unfortunately, data are not always available to answer all these questions at present, but hopefully the discussions will make us aware of what we do and do not know, and what we should look for in the near future.

A new angled transducer for intraoperative epicardial echocardiography

We tested a new angled transducer developed for intraoperative epicardial echocardiography in 42 patients. This small transducer, 70 x 20 x 15 mm in size, demonstrated superior operability and provided adequate two- or four-chamber imaging from the apical approach, which may lead to high-quality assessment with two-dimensional Doppler flow imaging.

Intraoperative epicardial echocardiography: early experience with a newly developed small surgical transducer

To test the feasibility of performing intraoperative echocardiography with a specially designed epicardial transducer, 20 adult patients were studied. All patients were undergoing coronary bypass surgery and had structurally normal intracardiac anatomy. The surgical transducer has 48 elements and a size at the tip of 10 x 12 x 5 mm. The scan plane has been set at 90 degrees to the cable axis to allow scanning from lateral positions. The terminal 10 cm of the cable has been reinforced to act as a malleable and steerable handle. Good quality images were obtained with the new transducer, and many different imaging planes were identified compared to imaging with the standard transducers. These include the right ventricular apex, the right and left lateral aspects of the heart, the aortic arch, and the pulmonary artery and its branches. The limitation of the probe was the difficulty in obtaining left ventricular apical views because of ventricular arrhythmias sustained when the transducer was placed between the left ventricular apex and the diaphragm. We conclude that this new transducer has a promising future in the application of intraoperative epicardial echocardiography.

Intraoperative echocardiography

Intraoperative echocardiography has emerged as a new technique by which the cardiac surgeon can more precisely define the operative anatomy and physiology, immediately evaluate the results, and more accurately monitor left ventricular function in the operating room. This review summarizes the current applications of intraoperative two-dimensional and Doppler echocardiography in both the epicardial and transesophageal forms, and discusses the advantages and possible limitations of these methods in the practice of clinical cardiac surgery.

Intraoperative echocardiographic assessment of global and regional myocardial function

Intraoperative echocardiography is gaining increasing importance to the anesthesiologist and the surgeon in the management of high-risk patients undergoing cardiac and major noncardiac surgery. It can provide for the noninvasive, immediate assessment of global left ventricular function, and its determinants; preload, afterload, and myocardial contractility. In addition, abnormalities of regional myocardial function, as a marker of myocardial ischemia, can be easily identified. With the advent of transesophageal echocardiography, this imaging technique can be more widely applied without interfering with the surgical procedure, not only increasing our ability to adequately monitor the patient, but also guiding our therapy and providing additional insights into the physiological and pathophysiological processes affecting the heart during surgery.

Effect of depressed left ventricular function on hemodynamics of normal St. Jude Medical prosthesis in the aortic valve position

To evaluate the effect of left ventricular (LV) dysfunction on Doppler-derived transprosthetic hemodynamic indexes in patients with normally functioning St. Jude aortic valve prostheses, 74 consecutive patients were studied. LV ejection fraction was assessed by using Simpson's biplane rule. The 34 patients with normal ejection fraction (greater than or equal to 0.51) (group A) generally had the highest values of peak (31 +/- 13 mm Hg) and mean (16 +/- 6 mm Hg) gradients, whereas 19 patients with moderate to severe reduction of ejection fraction (less than or equal to 0.31) (group C) had the lowest values (17 +/- 6 and 9 +/- 3 mm Hg, respectively) (p less than 0.05). Significant decreases (p less than 0.05) for acceleration and corrected (for heart rate) velocity time integral in group C were noted compared to group A, and group B (21 patients with mild to moderately reduced ejection fraction [0.50 to 0.32]). A significant inverse correlation for Doppler-derived peak and mean gradients and corrected velocity time integral was demonstrated with increasing aortic valve prosthetic sizes from 19 to 29 mm in group A patients (r = -0.41 to -0.71) but less so in group B or C. Thus, in addition to valve size, LV function should be considered an important factor in detecting prosthetic valvular flow characteristics and dysfunction. A normal derived velocity and gradient in patients with moderately to severely depressed LV function may not rule out significant valvular stenosis.

The utility of transesophageal echocardiography and Doppler color flow imaging in patients undergoing cardiac valve surgery

To assess the value of intraoperative transesophageal echocardiography during cardiac valve surgery, 154 consecutive patients who had a valve operation in conjunction with pre- and postcardiopulmonary bypass transesophageal imaging were studied. Prebypass imaging yielded unsuspected findings that either assisted or changed the planned operation in 29 (19%) of the 154 patients. Imaging immediately after bypass revealed unsatisfactory operative results that necessitated immediate further surgery in 10 (6%) of the 154 patients. Postbypass left ventricular dysfunction, prompting administration of inotropic agents, was identified in 13 patients (8%). Transesophageal echocardiography proved most useful when both two-dimensional and Doppler color flow imaging were employed in patients undergoing a mitral valve operation, where surgical decisions based on echocardiographic results were made in 26 (41%) of 64 cases. Postbypass echocardiographic findings identified patients at risk for an adverse postoperative outcome. Of 123 patients whose postbypass valve function was judged to be satisfactory, 18 (15%) had a major postoperative complication and 6 (5%) died, whereas of 7 patients with moderate residual valve dysfunction, 6 (86%) had a postoperative complication and 3 (43%) died (p less than 0.05 for both). Likewise, of 131 patients with preserved postbypass left ventricular function, 12 (9%) had a major complication and 7 (5%) died, whereas of 23 patients with reduced ventricular function, 17 (73%) had a postoperative complication and 6 (26%) died (p less than 0.05 for both). These data indicate that intraoperative transesophageal echocardiography is useful in formulating the surgical plan, assessing immediate operative results and identifying patients with unsatisfactory results who are at increased risk for postoperative complications.

Effects of coronary artery surgery on left ventricular performance, segmental wall movement, and exertional ischaemia

The effects of coronary artery surgery on left ventricular performance were assessed serially by echocardiography and treadmill exercise testing in 54 patients. Patients were assessed one day before operation and again before patients left hospital (mean 10 days after operation) and one month and six months after operation. At the predischarge assessment, 41 (77%) patients showed new abnormalities of left ventricular segmental wall movement, chiefly anteroseptal hypokinesia with hyperkinesia of the posterolateral segment. Although there were no significant changes in anteroseptal wall thickening after operation, there was a significant increase in posterior wall thickening at all postoperative assessments. The frequency of this abnormality decreased progressively after operation; it persisted in 19 (35%) patients at six months. Left ventricular fractional shortening decreased after operation and at one month was significantly less than before operation. There were no significant changes in left ventricular diastolic diameter during the study. Haemodynamic function during exercise, the duration of exercise, and features of reversible myocardial ischaemia all improved progressively and significantly after coronary artery surgery. Abnormalities in left ventricular segmental wall movement and thickening commonly develop early after coronary artery surgery but tend to resolve by six months and do not seem to impair left ventricular contractility at rest or exercise performance and haemodynamic function. Recognition of these echocardiographic changes may be clinically important in the assessment of patients after cardiac surgery.

Influence of coronary artery bypass surgery on regional left ventricular wall motion: An intraopertive two-dimensional transesophageal echocardiographic study

Two-dimensional transesophageal echocardiography was used to evaluate the effect of coronary revascularization on regional myocardial function in 30 patients. Cross-sections at the level of the papillary muscles were obtained 15 minutes after intubation, 15 minutes after sternal closure, and 6 and 12 hours later, in the intensive care unit. Regional myocardial function of eight segmental areas was obtained using a floating axis system. The segments were allocated to one of four conditions, depending on baseline regional area ejection fraction (RAEF): condition I) RAEF < 0%; condition II) RAEF = 0% to 25%; condition III) RAEF = 26% to 50%; or condition IV) RAEF > 50% (normal). Compared to baseline values (postinduction), RAEF changed after sternal closure in condition I from -10.4% +/- 5.4% to 17.6% +/- 10.3% (P < .01), in condition II from 14.3% +/- 6.1% to 30.7% +/- 7.8% (P < .01), and in condition III from 35.0% +/- 6.1% to 50.4% +/- 6.3% (P < .01). In condition IV there was no significant change in RAEF. Further improvement of RAEF in conditions I, II, and III was not seen in the intensive care unit. Thus, preoperative normal regional myocardial function was not affected by coronary revascularization, and dysfunctioning myocardium frequently improved immediately after revascularization.

Intraoperative two-dimensional echocardiography: new application of an old technique

Intraoperative two-dimensional echocardiography is a new diagnostic and monitoring technique that provides immediate information, unavailable from routine hemodynamic measurements, on both myocardial and valvular function. The presence and severity of valvular regurgitation can be assessed from the visualized flow pattern of microbubbles generated by an injection of saline solution: reflux flow into the retrograde chamber represents valvular insufficiency. The extent of valvular regurgitation can be determined immediately after conservative valve repair (annuloplasty or commissurotomy) or replacement to avoid the patient's leaving the operating suite with significant but undetected valvular insufficiency. Additionally, intraoperative echocardiography permits rapid evaluation of left ventricular systolic and diastolic volumes and myocardial contractility, thereby facilitating therapeutic interventions in the operating room. It also permits assessment of congenital heart defects and the competency of their repair. Pulsed, continuous and color-flow real time Doppler imaging methods allow further intraoperative definition of stenotic and regurgitant lesions.