Left ventricular ejection fraction during cardiac surgery: a two-dimensional echocardiographic study

Trileaflet Semilunar Valve Reconstruction: Acute Porcine in Vivo Evaluation

Objective: The surgical treatment of malformed semilunar valves in congenital heart defects is challenging in terms of providing both longevity and the potential to grow with the recipient. We investigated a new surgical technique "Trileaflet Semilunar Valve Reconstruction" in an acute porcine model, a technique with geometrical properties that could remain sufficient and allow for some growth with the child. Methods: An acute 60-kg porcine model was used. With echocardiography, baseline pulmonary valvular geometry and hemodynamics were investigated. On cardiopulmonary bypass, the pulmonary leaflets were explanted, and the Trileaflet Semilunar Valve Reconstruction was performed with customized homograft-treated pericardial neo-leaflets. Off bypass, hemodynamics was reassessed. Results: Twelve animals were investigated. The neo-valves were found sufficient in ten animals and with minimal regurgitation in two animals. The neo-valve had a peak gradient of 3 ± 2 mm Hg with a peak velocity of 0.8 ± 0.2 m/s. The coaptation in the neo-valve had a mean increase of 4 ± 3 mm, P < .001. The neo-valve had a windmill shape in the echocardiographic short-axis view, and the neo-leaflets billowed at the annular plane in the long-axis view. Conclusions: In this acute porcine model, the neo-valve had no clinically significant regurgitation or stenosis. The neo-valve had an increased coaptation, a windmill shape, and leaflets that billowed at the annular plane. These geometric findings may allow for sustained sufficiency as the annular and pulmonary artery dimension increase with the child's growth. Further long-term studies should be performed to evaluate the efficacy and the growth potential.

Survey Reported Participation in Cardiac Rehabilitation and Survival After Mitral or Aortic Valve Surgery

We sought to measure the impact of cardiac rehabilitation (CR) on mortality in patients with mitral or aortic heart valve surgery (HVS) and nonobstructive coronary artery disease. We surveyed all patients (or a close family member if the patient was deceased) who had HVS without coronary artery bypass in 2006 through 2010 at the Mayo Clinic to assess if they attended CR after their HVS. We performed a propensity-adjusted landmark analysis to test the association between CR attendance and long-term all-cause mortality conditional on surviving the first year after HVS. Survey response rate was 40% (573/1,420), with responders more likely to be older, have longer hospitalizations, and have more aortic valve disease. A total of 547 patients (59% aortic surgery, ejection fraction 64%) with valid survey responses and 1-year follow-up were included in the propensity analysis, of whom 296 (54%) attended CR. There were 100 deaths during a median follow-up of 5.8 years. For all patients, the propensity-adjusted model suggested no impact of CR on mortality (hazard ratio [HR] 1.03, 95% CI 0.66 to 1.62). When stratified by procedure, results suggested a potentially favorable, but nonsignificant, effect in patients with mitral valve surgery (HR 0.49, 95% CI 0.15 to 1.56), but not in patients with aortic valve surgery (HR 1.00, 95% CI 0.61 to 1.64.) In conclusion, we found no survival advantage for patients with normal preoperative ejection fraction who attended CR after surgical "correction" of their severe aortic or mitral valve disease.

Hemodynamic stability during biventricular pacing after cardiopulmonary bypass

OBJECTIVE

To assess the stability of cardiac output, mean arterial pressure, and systemic vascular resistance during biventricular pacing (BiVP) optimization.

DESIGN

Substudy analysis of data collected as part of a randomized controlled study examining the effects of optimized temporary BiVP after cardiopulmonary bypass (CPB).

SETTING

A single-center study at a university-affiliated tertiary care hospital.

PARTICIPANTS

Cardiac surgery patients at risk of left ventricular failure after CPB.

INTERVENTIONS

BiVP was optimized immediately after CPB. Atrioventricular delay (7 unique settings) was optimized first, followed by the left ventricular pacing site (3 unique settings) and then the interventricular delay (9 unique settings). Each setting was tested twice for 10 seconds each time. Vasoactive medication and fluid infusion rates were held constant.

MEASUREMENTS AND MAIN RESULTS

Aortic flow velocity and radial artery pressure were digitized, recorded, and averaged over single respiratory cycles. Least squares and linear regression/Wilcoxon analyses were applied to the first 7 patients studied. Subsequently, curvilinear analysis was applied to 15 patients. Changes in mean arterial pressure and systemic vascular resistance were statistically insignificant or too small to be meaningful by least squares analysis. During interventricular synchrony optimization, cardiac output and mean arterial pressure decreased (mean changes -5.7% and -2.5%, respectively; with standard errors 2.3% and 1.5%, respectively), whereas SVR increased (mean change 3.1% with standard error 3.4%). Only the change in cardiac output was statistically significant (p = 0.043). Curvilinear fits to data for 15 patients demonstrated progressive hemodynamic stability over the total testing period.

CONCLUSION

BiVP optimization may be done safely in patients after CPB. With continuous monitoring of mean arterial pressure and cardiac output, the procedure results in no harmful hemodynamic perturbation.

Left ventricular remodeling early after correction of mitral regurgitation: maintenance of stroke volume with decreased systolic indexes

OBJECTIVE

Mitral valve repair for mitral regurgitation is followed by left ventricle adjustment to new preload and afterload. We evaluated left ventricular geometry and function immediately after mitral valve repair for degenerative prolapse.

METHODS

We prospectively studied 25 patients undergoing mitral valve repair; 15 patients undergoing a coronary artery bypass graft served as controls to determine the impact of cardiopulmonary bypass and cardioplegic arrest on left ventricular function. Intraoperative transesophageal echocardiography was conducted after sternotomy before initiation of cardiopulmonary bypass and after termination of cardiopulmonary bypass and protamine infusion. Simultaneous pulmonary catheter data ensured that the images were obtained under similar hemodynamic conditions.

RESULTS

Immediately after mitral valve repair, left ventricular fractional area change decreased significantly from 65% ± 7% to 52% ± 8% (P < .001). Left ventricular end-diastolic area decreased minimally (21.3 ± 5.3 cm(2) vs 19.4 ± 4.5 cm(2); P = .005), whereas left ventricular end-systolic area increased significantly (7.5 ± 2.3 cm(2) vs 9.3 ± 2.5 cm(2); P < .001). Notably, forward stroke volume (thermodilution) remained similar (63 ± 24 mL vs 66 ± 19 mL; P = .5). No significant difference was found in controls between pre- cardiopulmonary bypass and post-cardiopulmonary bypass fractional area change (54% ± 12% vs 57% ± 10%; P = .19), left ventricular end-diastolic area (16.6 ± 6.2 cm(2) vs 15.7 ± 5.0 cm(2); P = .32), and stroke volume (72 ± 29 mL vs 65 ± 19 mL; P = .15); they had a slight decrease in left ventricular end-systolic area (7.9 ± 4.4 cm(2) vs 6.9 ± 3.2 cm(2); P = .03).

CONCLUSIONS

Early after correction of mitral regurgitation, left ventricular fractional area change decreases significantly, primarily as the result of a larger end-systolic dimension. This may be a compensatory mechanism to prevent augmentation of forward stroke volume after mitral valve repair.

Ventricular function in surgery for congenital heart disease

BACKGROUND The history of measuring myocardial edema by two-dimensional echocardiography and the pathophysiology of myocardial edema are reviewed. METHODS The relevance of this subject to management of children undergoing corrective surgery for single ventricle physiology and tetralogy of Fallot is reviewed. RESULTS Evidence is presented that myocardial edema is an ongoing clinical problem with relevance to management and outcomes. Methods for measuring mass increases noninvasively in the range of 10-25% with increases in myocardial water content on the order of 2-4% are now well established. CONCLUSIONS These methods and advanced animal models replicating conditions of surgery for cyanotic congenital heart disease set the stage for clinical advances in this important area.

Autologous Skeletal Myoblast Transplantation Improved Hemodynamics and Left Ventricular Function in Chronic Heart Failure Dogs

BACKGROUND

Previous studies have suggested that autologous skeletal myoblast transplantation (ASMT) improves left ventricular (LV) function in small animals after myocardial infarction. We tested the effects of ASMT on hemodynamics, LV function and remodeling in coronary microembolization-induced chronic heart failure (CHF) in conscious dogs.

METHODS

Nineteen dogs were continuously instrumented with LV pressure sensors and mid-myocardial sonomicrometry crystals for dP/dt(max) and LV volume determination. Each dog underwent baseline assessment in a conscious state. CHF (20% to 30% reduction in dP/dt(max) and LV end-diastolic pressure >16 mm Hg) was created by daily coronary microembolizations via a continuously implanted coronary catheter. Skeletal muscle biopsy was performed and myoblasts were isolated and expanded. Then 2.7 x 10(8) to 8.3 x 10(8) myoblasts were injected into the infarcted region of 11 dogs after establishment of CHF. Saline injection (sham) was performed in 8 control dogs. Animals were evaluated every 2 weeks for up to 10 weeks. Global ejection fraction was determined by echocardiography. The end-systolic pressure-end-systolic volume relationship (ESPVR) was analyzed by the Sonomicrometic system.

RESULTS

Compared with saline injection, ASMT significantly increased dP/dt(max) (105 +/- 9% vs 97 +/- 7%, values were expressed as percentage change from baseline CHF, p = 0.013) and ejection fraction (46 +/- 3% vs 40 +/- 2%, p = 0.034) at 10 weeks after myoblast transplantation. There was a significant leftward and upward shift of the ESPVR back toward normal at 10 weeks after myoblast transplantation (p = 0.034). Three animals labeled with BrdU myoblasts showed no histologic evidence of viable engraftment.

CONCLUSIONS

ASMT provided mild improvements in hemodynamics and LV function and reduced LV remodeling in conscious dogs with CHF.

Early and late effects of coronary artery bypass grafting on cardiac haemodynamics during daily physical activities in patients with coronary artery disease

This study investigated the early and late effects of coronary artery bypass grafting (CABG) on left ventricular (LV) function during different physical daily activities in patients with multivessel coronary artery disease (CAD). In ten patients with multivessel CAD, cardiac haemodynamics were assessed during a 6-min walk test and during stair climbing 8+/-2 days before (study 1) and 15+/-3 days (study 2) and 120+/-3 days (study 3) after CABG. LV function was monitored by an ambulatory radionuclide system. In study 1, the walk test induced a significant increase in relative end-diastolic volume (EDV) and end-systolic volume (ESV) and no change in LV ejection fraction as compared to rest. In both study 2 and study 3, EDV increased significantly and ESV was unchanged. As a consequence, LV ejection fraction rose from 48%+/-8% to 52%+/-10% and from 48%+/-7% to 51%+/-6%, respectively (both P<0.05). In study 1, stair climbing induced a significant increase in EDV and ESV and as a consequence LV ejection fraction decreased from 46%+/-8% to 42%+/-9% (P<0.05) as compared to rest. In both study 2 and study 3, EDV increased significantly whereas ESV did not change. As a consequence, LV ejection fraction rose from 48%+/-8% to 52%+/-7% and from 48%+/-8% to 51%+/-7%, respectively (both P<0.05). In conclusion, CABG has beneficial effects on cardiac performance during moderate or more intense physical activity in patients with multivessel CAD and these effects are due to improvement in systolic function. Radionuclide monitoring of LV function provides an objective method for quantitative evaluation of cardiac performance after CABG.

Echocardiographic analysis of ventricular geometry and function during repair of congenital septal defects

BACKGROUND

This study investigated changes in left ventricular (LV) geometry and systolic function after corrective surgery for atrial (ASD) and ventricular septal defects (VSD).

METHODS

Transesophageal LV short-axis echocardiograms were recorded before and after operative repair of ASD (n = 11) and VSD (n = 7). Preload was measured using LV end-diastolic area indexed for body surface area. Measurements of septal-freewall (D1) and anterior-posterior (D2) endocardial diameters were used to assess LV symmetry from D1/D2. Systolic indices included stroke area, area ejection fraction, and fractional shortening.

RESULTS

Preload, stroke area, area ejection fraction, and fractional shortening of D1 increased after ASD repair but decreased after VSD repair (p < 0.05). End-diastolic symmetry increased after ASD closure and decreased after VSD closure (p < 0.05). Increases in stroke area and ejection fraction after ASD correction primarily reflected increased shortening of D1. A positive correlation was found overall between percent change in end-diastolic area (EDA) and percent change in area ejection fraction (r(2) = 0.80, p < 0.0001, n = 18).

CONCLUSIONS

Preload was the primary determinant of changes in LV function in this series of ASD and VSD repairs. Intraoperative changes in position of the interventricular septum affected systolic and diastolic LV symmetry and septal free wall shortening. Additional studies are needed to define changes in afterload and contractility as well as diastolic compliance and systolic mechanics.

Validation of left ventricular end-diastolic volume from stroke volume and ejection fraction

The present study examines an innovative approach to measurement of left ventricular (LV) end-diastolic volume (LVEDV). Measurement of LVEDV is fundamental to the assessment of intraoperative systolic and diastolic LV function. We compared steady state LVEDV values obtained from stroke volume (SV) and ejection fraction (EF) with echocardiographic and postmortem LVEDV measurements. Five anesthetized pigs (40-45 kg) underwent median sternotomy and pericardiotomy. A transit time ultrasonic flow probe was placed on the ascending aorta to provide cardiac output. A micromanometer provided LV end-diastolic pressure. LV short axis cross sectional echocardiograms and electrocardiograms were also obtained. LV end-diastolic area (LVEDA) and end-systolic area (LVESA) were measured to obtain EF. LVEDVsv/ef was calculated from cardiac output, heart rate, and EF. LVEDVecho was determined using a three-plane echocardiography model. Postmortem (LVEDVpm/vv) volumes were also measured. LVEDVsv/ef correlated well with volumes obtained by echocardiography (r2 = 0.92) and postmortem (r2 = 0.73) measurements. Values of p < 0.05 indicated significant linearity of LVEDA-LVEDVsv/ef (r2 =0.93), LVEDA-LVEDVecho (r2 = 0.96), and LVEDA-LVEDVpm/vv (r2 = 0.81) relationships. Determination of LVEDV from SV and EF is valid and may facilitate real-time determination of LV mechanics.

Left ventricular end-diastolic volume from ejection fraction and stroke volume in pigs during IVC occlusion

BACKGROUND

Real-time measurement of left ventricular end-diastolic volume (LVEDV), combined with left ventricular end-diastolic pressure (LVEDP), would allow continuous measurement of intraoperative diastolic function. In pursuit of this goal, we examined stroke volume divided by ejection fraction for calculation of LVEDV(sv/ef).

METHODS

Five anesthetized pigs underwent median sternotomy and pericardiotomy. A transit-time ultrasonic flow probe on the ascending aorta provided cardiac output. A micromanometer provided LV end-diastolic pressure. End-diastolic and end-systolic areas were measured from LV short-axis cross sections to obtain ejection fraction. LVEDV(sv/ef) was calculated during IVC occlusion. Steady-state LVEDV(echo) was determined using a three-plane echocardiography model. LVEDV(echo) was used to validate steady-state LVEDA in each experiment.

RESULTS

Correlation coefficients for linear and pressure-volume relation analyses ranged from 0.46 to 0.99. The two methods for measuring LVEDV generated compliance curves with an overall reliability coefficient of 0.84.

CONCLUSIONS

The LVEDV(sv/ef) method may facilitate real-time determination of LV compliance.

Segmental wall motion abnormalities during telerobotic totally endoscopic coronary artery bypass grafting

In addition to single-lung ventilation (SLV), intrathoracic CO2 insufflation is mandatory for adequate exposure during totally endoscopic coronary artery bypass grafting. With transesophageal echocardiography, we investigated biventricular myocardial wall motion in 25 patients with isolated disease of the left anterior descending coronary artery who underwent totally endoscopic coronary artery bypass grafting with the "Da Vinci" robotic surgical system. At distinct time points during the operation, a cine loop of both ventricles was registered from a transgastric mid-short-axis view. Myocardial wall motion analysis was performed according to an established segmentation model of the left ventricle and to an established five-point scale for wall motion (1, normal; 5, dyskinesia). Significant alterations from preoperative baseline wall motion were visible in the septal, inferior, and anterior segments of the left ventricle at some time during the prebypass period, combined with a markedly decreased PaO2 under SLV and increased intrathoracic pressure. The same findings applied to the right ventricle; however, wall motion abnormalities were more pronounced here. After myocardial revascularization, weaning from cardiopulmonary bypass, CO2 deflation, and return to double-lung ventilation, myocardial wall motion recovered to baseline values. Clinically significant hemodynamic instability did not occur. The data suggest that robot-assisted coronary artery bypass grafting leads to significant prebypass alterations of biventricular segmental wall motion. On the basis of our data, it cannot be definitively stated whether the observed results were due to reduced oxygenation during SLV and thus "real" myocardial ischemia, intrathoracic CO2 insufflation with positive pressure leading to mechanical compromise of the heart, absolute or relative hypovolemia, or a combination of these factors. However, in this cohort, which consisted of patients with single-vessel disease and good ventricular function, these changes were of limited clinical relevance.

IMPLICATIONS

Segmental myocardial wall motion was evaluated with transesophageal echocardiography during robot-assisted totally endoscopic coronary artery bypass grafting. Significant biventricular segmental wall motion abnormalities occurred before cardiopulmonary bypass under single-lung ventilation and carbon dioxide insufflation. The changes in myocardial wall motion were of limited clinical relevance.

Performing a complete transesophageal echocardiographic examination

Transesophageal echocardiographic (TEE) examination is a powerful and informative cardiac monitor and an important diagnostic tool for use during cardiac surgery. This article reviews how to perform a comprehensive TEE examination on a patient in the operating room and the important clinical uses of TEE during critical events.

Intraoperative echocardiography: interpretation of changes in left ventricular wall thickness

Quantitative two-dimensional echocardiography (Q2-DE) may be used to detect intraoperative changes in left ventricular (LV) mass (M) and wall thickness (h). Potential causes of change in h include physiological redistribution of myocardium, myocardial edema, reactive hyperemia, and intramyocardial hemorrhage. Changes in h, in the absence of changes in LV shape and volume, generally indicate increased LVM. When changes in h are accompanied by changes in shape or volume, changes in LVM can only be detected by mathematical modeling, unless the direction of the observed changes is opposite that expected with physiological redistribution. Histological observations essential to understanding current mathematical models are presented and related to the inherent solid geometry. Technical considerations in determination of LV mass by Q2-DE are discussed. New procedures that alter LV volume and geometry, such as the Batista operation, defy modeling by conventional methods. Modeling techniques that allow an experimental approach to understanding LVM and h under such conditions are presented.

Evaluation of Ventricular dP/dt Before and After Open Heart Surgery Using Transesophageal Echocardiography

The mean dP/dt during isovolumetric contraction (mean dP/dt(ic)) is a new echocardiographic index of ventricular function that has been shown to approximate and closely correlate with invasively measured peak dP/dt. It is amenable to rapid measurement via transesophageal echocardiography (TEE) and is theoretically independent of variations in ventricular anatomy and wall motion. It is therefore well suited for the assessment of ventricular function during surgery. The purpose of this study was to assess the clinical value of TEE determinations of mean dP/dt(ic) before and after cardiopulmonary bypass (CPB). The mean dP/dt(ic) of 50 patients undergoing open heart surgery for a variety of congenital and acquired heart defects was measured before and 15-30 minutes after CPB. Mean dP/dt(ic) averaged 1147 +/- 492 before and 1428 +/- 702 mmHg/sec after CPB (P < 0.01). Mean dP/dt(ic) was unchanged or increased in 45 patients and fell in only 5 patients. It increased significantly even among patients who did not receive supplemental inotropic agents. Mean dP/dt(ic) correlated well with the shortening fraction, especially among patients without segmental left ventricular wall-motion abnormalities. The general patterns observed for mean dP/dt(ic) were also seen when the data was corrected for variations in heart rate. A preoperative mean dP/dt(ic) < 765 mmHg/sec or a heart rate corrected mean dP/dt(ic) < 620 mmHg/sec indicated a high likelihood that inotropic support would be needed to facilitate weaning from CPB. Mean dP/dt(ic) may be a clinically useful, quantitative TEE index of perioperative changes in ventricular contractility.

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.

Myocardial dysfunction following cardiopulmonary bypass: recovery patterns, predictors of inotropic need, theoretical concepts of inotropic administration

Clinical myocardial dysfunction following cardiopulmonary bypass commonly occurs in patients with good preoperative ventricular function. Following separation from cardiopulmonary bypass, ventricular function improves initially, but then begins to worsen and reaches a nadir between 4 and 6 hours after surgery with full recovery occurring around 24 hours postoperatively. However, in patients with preoperative ventricular dysfunction, the depression of ventricular function is more severe and recovery is longer. Despite this high frequency of myocardial dysfunction, many patients do well without requiring pharmacologic intervention after cardiopulmonary bypass to augment contractility and peripheral perfusion. Factors that may predict the need for inotropic support in patients following cardiopulmonary bypass include low ejection fraction, older age, cardiac enlargement, female sex, the length of cardiopulmonary bypass and the duration of aortic cross-clamping. The patient with preoperative ventricular dysfunction has many of these preoperative and intraoperative predictors for inotropic support. The pharmacologic regimen to support the myocardium during the recovery period following cardiopulmonary bypass must take into consideration the pathophysiologic processes of chronic congestive heart failure and reperfusion injury. Reduction of cyclic adenosine monophosphate (cAMP) levels is a fundamental problem in congestive heart failure and results from either down-regulation of beta-receptors or a defect in the G-regulatory proteins controlling adenylyl cyclase production. This diminishes the effectiveness of agents dependent on cAMP to produce an inotropic response. However, amplification of the reduced cAMP produced by beta-agonists may occur in association with the inhibition of cAMP breakdown resulting from phosphodiesterase inhibitors. All inotropic agents are usually effective in reversing the reperfusion-induced stunned myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular function under stress before and after myocardial revascularization

To compare left ventricular responses to stress during exercise-induced myocardial ischemia and after myocardial revascularization, 35 patients (mean age 55 +/- 7 years, class III angina) with three-vessel coronary artery disease underwent a rest and exercise initial-transit radionuclide angiocardiography before aortocoronary bypass grafting. Left ventricular ejection fraction decreased during exercise (p less than 0.01), but cardiac output was augmented with an increased heart rate (p less than 0.0001) and left ventricular end-diastolic volume (p less than 0.001). Group A (n = 15) underwent six serial resting studies at different volume loads during the first 24 hours after operation while heart rate and blood pressure were held constant. These data revealed no significant change in left ventricular ejection fraction, but preload varied in all patients because of bleeding and fluid administration, with a mean end-diastolic volume change of 115 to 176 ml. This range of end-diastolic volume was similar to that defined with rest and exercise testing before operation. Group B (n = 20) underwent a repeat rest and exercise test 3 months after operation that demonstrated no change in resting function. However, exercise ejection fraction and peak systolic pressure/end-systolic volume ratio increased (p less than 0.001 and p less than 0.05, respectively) while end-diastolic volume decreased (p less than 0.05) compared with the values before operation. These data indicate that patients with coronary artery disease have chronically adapted cardiac function that makes use of both rapid heart rate and a wide range in preload to augment cardiac function under stress.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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 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.

Chronic aortic regurgitation: indications for operation--1988

Timing of operation in a patient with severe aortic regurgitation is a difficult and controversial decision, especially when the patient is asymptomatic or minimally symptomatic. A rational decision can be made when the pathophysiologic features of aortic regurgitation and the natural history of medically treated patients are understood and the benefits and risks associated with aortic valve replacement are known. Proper interpretation of the literature involving echocardiography and nuclear cardiology is essential, as is consideration of the constantly changing surgical techniques and results. Aortic valve replacement should be recommended for those patients with chronic aortic regurgitation who are severely symptomatic (New York Heart Association Functional Class III or IV), in order to ameliorate symptoms and increase longevity. In asymptomatic or minimally symptomatic patients, close continued serial follow-up is necessary in order to detect the onset of resting left ventricular dysfunction and to recommend the optimal timing for surgical intervention.

Effect of electrophysiological testing on ejection fraction during cardioverter/defibrillator implantation

To evaluate the effect of repeated induction of ventricular tachycardia or ventricular fibrillation, or both, in patients with poor left ventricular function, we performed intraoperative two-dimensional echocardiography in 6 patients undergoing implantation of the automatic implantable cardioverter/defibrillator. Changes in left ventricular ejection fraction in sinus rhythm were assessed before the first inducible ventricular arrhythmia and after a mean of 6 +/- 1.9 (SD) episodes of ventricular tachycardia or ventricular fibrillation. During the procedure no significant change in mean ejection fraction was observed (28 +/- 14 versus 27 +/- 17%). Only 1 of the 6 patients studied had a change in ejection fraction greater than 3% (a decrease from 20 to 11%). In an overall clinical series of 38 primary implants or generator changes (including electrophysiological testing) in 29 patients, 1 patient recovered after postoperative inotropic support and 1 died of acute postoperative ischemic heart failure. We conclude that ventricular arrhythmias induced during automatic implantable cardioverter/defibrillator implantation have no immediate deleterious effects on ejection fraction in most patients with compromised left ventricular function and without ongoing ischemia.

Myocardial metabolism, catecholamine balance, and left ventricular function during coronary artery surgery: effects of nitroprusside and nifedipine

The effects of nitroprusside and nifedipine on myocardial oxygen consumption (MVO2), catecholamine release, and left ventricular (LV) function (using 2D transesophageal echocardiography) were compared. Thirty-seven patients undergoing coronary artery surgery, anesthetized with fentanyl, 100 micrograms/kg, were studied. All had good LV function and had been receiving long-term oral beta-blocking therapy. Patients were randomly allocated to one of three groups. Group C (n = 12) received no vasodilator and served as control. Group S (n = 13) received nitroprusside at an initial rate of 1 microgram/kg/min. Group N (n = 12) received nifedipine at an initial rate of 0.7 microgram/kg/min. Baseline measurements were obtained ten minutes after intubation. Vasodilator therapy was then started in groups S and N. Infusion rates were adjusted to maintain systolic blood pressure (SBP) between 80% and 120% of baseline values. Additional measurements were made ten minutes after the start of the infusion, ie, before surgery (in group C immediately before surgery), and after sternotomy when the pericardium was opened. The mean (+/- SD) total dose requirements were 1.9 +/- 0.5 micrograms/kg/min for nitroprusside and 1.1 +/- 0.2 micrograms/kg/min for nifedipine. The mean (+/- SD) total infusion time was 31 +/- 5 minutes for nitroprusside and 32 +/- 11 minutes for nifedipine. After sternotomy, heart rate increased in all groups. At this time arterial blood pressure and systemic vascular resistance (SVR) increased in group C. SVR was decreased after the first ten minutes of nitroprusside infusion and after sternotomy in group S. Coronary sinus blood flow, MVO2, and myocardial norepinephrine release increased in group N, but not in groups C or S. After sternotomy, LV percentage area reduction increased in groups S and N, but not in group C. In group N there was a significant correlation (r = 0.65; P less than .05) between the increases in MVO2 and LV percentage area reduction, an estimate of myocardial function. Lactate production occurred in two patients in group C after sternotomy. This was not associated with ECG changes, but in one patient regional wall motion abnormalities developed. No evidence of myocardial ischemia was observed in groups S and N. However, in contrast to nitroprusside, the use of nifedipine was associated with increases in MVO2, myocardial norepinephrine release, and inotropy.

Transoesophageal echocardiographic monitoring of left ventricular function

Technical advances in echocardiography, especially the introduction of oesophageal probes, have led to the extension of its indications to the field of anaesthesia and intensive care. Transoesophageal echocardiography (TEE) provides high quality imaging of the left ventricle in patients on ventilators. In addition, manipulation of the probe is performed near the patient's head and so does not interfere with the surgeon's job. This enables echocardiographic monitoring of left ventricular function throughout the operation. The information so obtained not only provides data about anatomical changes which is sometimes invaluable, but also allows quantification of left ventricular function which is the main advantage for anaesthetists. The images allow study of regional and global left ventricular contraction and the deduction of certain parameters of ventricular performance. The ability to perform real time monitoring of ventricular function throughout anaesthesia and the immediate postoperative period is all the more valuable in patients with limited cardiac and coronary reserve. This new method of monitoring gives a better understanding of the physiopathology of peroperative cardiac events and provides information which may guide the conduct of the anaesthesia and postoperative care.

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.

Unreliability of hemodynamic indexes of left ventricular size during cardiac surgery

Pulmonary artery diastolic (PADP) and wedge pressures (PAWP) and left ventricular end-diastolic pressure (LVEDP) are commonly used to estimate left ventricular (LV) preload. To assess the ability of hemodynamic indexes of preload to estimate anatomical preload, or LV volume, we studied 45 patients during a coronary (18 patients) or aortic valve (27 patients) procedure and compared epicardial two-dimensional echocardiographic LV cavity area with simultaneous measurements of PADP, PAWP, and high-fidelity LVEDP. Pulmonary artery diastolic pressure, PAWP, and their percent change after bypass did not correlate with absolute values (before or after bypass) or percent change in LVEDP. Percent change in LV area correlated weakly with percent change in PADP (r = .34, p less than .03) but not with changes in PAWP or LVEDP. Changes were opposite in direction in 45% (PADP), 50% (PAWP), and 67% (LVEDP) of patients. In conclusion, both PADP and PAWP were poor guides to LVEDP and neither reflected changes in LV size. Thus, hemodynamic indexes of preload should be used with caution during cardiac operations.

Mechanisms of the development and resolution of paradoxical interventricular septal motion after uncomplicated cardiac surgery

Of 16 patients with normal preoperative left ventricular (LV) function studied by simultaneous two-dimensional and M-mode echocardiography before and after uncomplicated cardiac surgery, M-mode interventricular septal motion remained normal in seven (group I) and was paradoxical in nine (group II) 7 to 13 days postoperatively, but was normal in all 12 patients (7 group II) studied 3 to 18 months later. An abnormal systolic increase in normalized septal curvature, the essential feature of truly paradoxical septal motion, was not observed in either group during any study period (mean = 0.92 +/- 0.08), nor were significant differences found in septal thickening, LV fractional shortening, or fractional area change. In contrast, systolic anterior motion of the LV center increased from -0.1 +/- 1.6 mm preoperatively to 4.8 +/- 2.5 mm postoperatively in group II (p less than 0.001), and the LV posterior wall motion:thickening ratio increased from 1.10 +/- 0.33 to 2.16 +/- 0.45 (p less than 0.01), but both parameters had returned to preoperative levels at the follow-up study. Both parameters remained stable in group I during all study periods. In addition, direct intraoperative M-mode recordings (n = 14) demonstrated normal septal motion in both groups before chest closure, but esophageal echocardiograms (n = 10) demonstrated exaggerated anterior systolic LV motion within 2 hours of surgery in those from group II. Thus, early after uncomplicated cardiac surgery, apparently paradoxical septal motion relative to a fixed reference point is an artifact due to exaggerated cardiac mobility that resolves with the progressive restraining effect of postoperative adhesions.

Assessment of successful valve reconstruction by intraoperative transesophageal echocardiography (TEE)

In 17 patients (10 patients with mitral insufficiency, 5 patients with tricuspid regurgitation, 2 patients with mitral stenosis) the result of valve reconstruction was evaluated by intraoperative two-dimensional transesophageal contrast-echocardiography (TEE). Therefore, 1-2cc of an agitated contrast-medium (Gelifundol) were injected into the left or right ventricle. The result of reconstruction was assessed by the extent of regurgitant microbubbles into the left or right atrium. A successful valve repair could be demonstrated in 15 patients without or with only minimal regurgitation of contrast-fluid. In one patient residual severe mitral insufficiency after valve reconstruction could only be detected when valve function was examined by contrast-TEE in the beating heart. An intraoperative decision for valve replacement was made. In another patient, mild to moderate residual mitral incompetence was shown; no further surgical intervention was done. By TEE the function of reconstructed valves can be examined under physiological conditions in the beating heart. Surgeons can obtain additional intra-operatively information and certainty about the result of reconstruction and an early decision for valve replacement can be made if necessary.

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.

Some electrical and pharmacological properties of gap junctions between adult ventricular myocytes

Ventricular myocytes were isolated from adult rat hearts using the technique of Wittenberg and Robinson (Cell Tissue Res. 216: 231-251, 1981). These cells exhibited morphology, input resistance, time constant, and excitability expected for cells in intact cardiac tissue. Pairs of these cells were electronically coupled, and junctional conductance was unaffected by transjunctional potential or hyperpolarization of both cells. Brief exposure of cell pairs to medium equilibrated with 100% CO2 or containing 0.1 mM octanol quickly and reversibly decreased junctional conductance. We conclude that gap junctions between pairs of ventricular myocytes possess physiological properties like those of junctions in many other tissues. This preparation will be useful in evaluating drug action on junctional communication in heart.

Predictive value of early maximal exercise test and thallium scintigraphy after successful percutaneous transluminal coronary angioplasty

Restenosis of the dilated vessel after percutaneous transluminal coronary angioplasty can be detected by non-invasive procedures but their ability to predict later restenosis soon after a successful angioplasty as well as recurrence of angina has not been assessed. A maximal exercise test and myocardial thallium perfusion scintigraphy were, therefore, performed in 91 asymptomatic patients a median of 5 weeks after they had undergone a technically successful angioplasty. Primary success of the procedure was confirmed by the decrease in percentage diameter stenosis from 64(12)% to 30(13)% as measured from the coronary angiograms and in the trans-stenotic pressure gradient (normalised for mean aortic pressure) from 0.61(0.16) to 0.17(0.09). A clinical follow up examination (8.6(4.9) months later) was carried out in all patients and a late coronary angiogram obtained in 77. The thallium perfusion scintigram showing the presence or absence of a reversible defect was highly predictive for restenosis whereas the exercise test was not. The positive predictive value of an abnormal scintigram was 82% compared with 60% for the exercise test (ST segment depression/or angina or both at peak workload). Angina or a new myocardial infarction occurred in 60% of patients with abnormal and in 21% of patients with normal scintigrams.

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

Intraoperative two-dimensional echocardiography (2DE) was performed in 15 patients during coronary artery bypass grafting (CABG) and in 14 patients during aortic (AVR) or mitral valve replacement (MVR) before and immediately after cardiopulmonary bypass by means of a 3.5 MHz transducer. Left ventricular ejection fraction (LVEF), end-diastolic (LVEDV) and end-systolic (LVESV) volumes were measured by a light pen system and biplane Simpson's rule from short-axis and apical two-chamber views. In seven patients with CABG and new abnormal Q waves or greater than 5% MB to total CPK ratio postoperatively, the mean LVEF decreased significantly (from 52 +/- 10 to 43 +/- 12%, p = 0.005). Patients undergoing MVR for mitral regurgitation showed, a significant decrease in LVEF (from 63 +/- 10 to 42 +/- 23%, p less than 0.025) and LVEDV (from 166 +/- 34 to 147 +/- 44 ml, p less than 0.05). Mean LVEF also decreased after AVR for aortic regurgitation (from 46 +/- 16 to 26 +/- 15%, p less than 0.05). Six patients with valve replacement and postoperative hypotension had the greatest decrease in intraoperative LVEF (from 50 +/- 12 to 24 +/- 10%, p less than 0.005). It is concluded that: Intraoperative 2DE can be used to assess immediate changes in left ventricular function after CABG or valve replacement. LVEF decreases significantly immediately after AVR for aortic regurgitation and MVR for mitral regurgitation. Intraoperative 2DE may identify those patients who can benefit from inotropic support in the immediate postoperative period after valve replacement.

Intraoperative cardioplegic contrast echocardiography for assessing myocardial perfusion during open heart surgery

Aortic root hypothermic, hyperkalemic cardioplegic perfusion has been shown to preserve ventricular function during open heart surgery. However, significant coronary artery stenoses may prevent adequate perfusion of myocardial regions distal to the lesions, leading to intraoperative ischemia and damage. The purpose of this study was to evaluate for the first time in human patients the use of intraoperative contrast cardioplegic echocardiography for identifying potentially jeopardized myocardial regions as defined by cardiac catheterization. Forty-two patients, 23 men and 19 women, aged 28 to 83 years (mean 56.7 +/- 2), who had undergone cardiac catheterization and coronary arteriography, underwent open heart surgery; 30 had coronary artery disease. Echocardiograms of the left ventricle, performed on the open heart in the papillary muscle short-axis plane during routine aortic root cardioplegia were divided into three regions according to the coronary anatomy: septal (left anterior descending artery), anterolateral (left circumflex) and inferoposterior (right coronary artery). Intraoperatively, myocardial segments at greatest potential ischemic risk were identified by several findings alone or in combination: lack of spontaneous contrast and delayed whiting out or persistent fine fibrillation. The ability of intraoperative echographic interpretation to identify high risk segments based on preoperative catheterization findings was excellent. Thus, the sensitivity of cardioplegic contrast echocardiography for predicting significant (greater than 70% stenosis) coronary lesions was 96, 100 and 58% for left anterior descending, left circumflex and right coronary artery regions, respectively. Specificity was 94, 78 and 100% for anterior descending, circumflex and right coronary artery regions, respectively. Overall sensitivity and specificity for all regions was 82 and 92%, respectively. Importantly, the echocardiogram was most helpful in observing septal region perfusion.(ABSTRACT TRUNCATED AT 250 WORDS)