Mitral flow propagation velocity identifies patients with abnormal diastolic function during coronary artery bypass graft surgery

What Is the Heart? Anatomy, Function, Pathophysiology, and Misconceptions

Cardiac dynamics are traditionally linked to a left ventricle, right ventricle, and septum morphology, a topography that differs from the heart's five-century-old anatomic description of containing a helix and circumferential wrap architectural configuration. Torrent Guasp's helical ventricular myocardial band (HVMB) defines this anatomy and its structure, and explains why the heart's six dynamic actions of narrowing, shortening, lengthening, widening, twisting, and uncoiling happen. The described structural findings will raise questions about deductions guiding "accepted cardiac mechanics", and their functional aspects will challenge and overturn them. These suppositions include the LV, RV, and septum description, timing of mitral valve opening, isovolumic relaxation period, reasons for torsion/twisting, untwisting, reasons for longitudinal and circumferential strain, echocardiographic sub segmentation, resynchronization, RV function dynamics, diastolic dysfunction's cause, and unrecognized septum impairment. Torrent Guasp's revolutionary contributions may alter future understanding of the diagnosis and treatment of cardiac disease.

Left Ventricular Velocity of Propagation: A Useful Non-Invasive Measurement When Assessing Hemodynamic Alterations in Pulmonary Arterial Hypertension

Background

Left ventricular (LV) velocity of propagation (Vp) has been shown to be inversely related to the LV relaxation time constant. We sought to examine Vp from a group of chronic pulmonary hypertension (cPH) patients and compare these values to Vp obtained in normal individuals and patients with known LV diastolic dysfunction (LVDD).

Methods

Echo-Doppler data and Vp measurements were retrospectively collected from all patients. The studied population was divided into four groups. Group I comprised of 15 patients with normal LV diastole, group II included 27 patients with stage 1 LVDD, group III was made up of 27 patients with stage 2 LVDD, and group IV included 66 patients with cPH.

Results

In the cPH population studied, patients had smaller end-diastolic LV cavities with the highest Vp values but their early mitral inflow to Vp ratios were not different from healthy controls. In addition, Vp values and pulmonary wedge capillary pressures were significantly associated in patients with LV dysfunction or pulmonary hypertension (P < 0.01).

Conclusions

LVVp might be a useful non-invasive measurement to be routinely obtained in cPH patients as it probably not only reflects the compressive forces being exerted on the LV, known to increase Vp, but also might be quite useful for the non-invasive assessment of pulmonary capillary wedge pressures in these patients.

Predictors and Clinical Impacts of Aggravated Left Ventricular Diastolic Dysfunction After Off-Pump Coronary Artery Bypass Grafting

BACKGROUND

To determine the predictors of aggravated left ventricular diastolic dysfunction (LVDD) in patients undergoing off-pump coronary artery bypass grafting (OPCAB) and to compare late outcomes according to the aggravated LVDD.

METHODS AND RESULTS

OPCAB was performed in 1,101 patients (2001-2013). LVDD was classified as normal, mild, moderate or severe. Patients were divided into 2 groups: non-aggravated LVDD (group I) and aggravated LVDD (group II). The primary endpoint was aggravation of LVDD. The secondary endpoint was late mortality and morbidity such as major adverse cardiac and cerebrovascular events (MACCE) related to LVDD aggravation postoperatively. There were 894 patients in group I and 207 in group II. Multivariate analysis revealed that preoperative peripheral artery obstructive disease (PAOD) (P=0.04), renal failure (P<0.01), and A' velocity (P<0.01) anticipated aggravated LVDD. The Cox hazards model revealed that aggravated LVDD was a poor prognostic factor for MACCE (P<0.01) and overall survival (P<0.01). The Kaplan-Meier survival curve showed that aggravated LVDD was related to poor late outcomes (freedom from MACCE, P=0.01; overall survival, P<0.01).

CONCLUSIONS

Aggravated LVDD significantly affects late clinical outcomes after OPCAB and preoperative PAOD, renal failure, and A' velocity might be predictors. (Circ J 2016; 80: 1937-1945).

Influence of intraaortic balloon pump counterpulsation on transesophageal echocardiography derived determinants of diastolic function

Introduction

Intraaortic balloon pump counterpulsation (IABP) is often used in patients with acute coronary syndrome for its favourable effects on left ventricular (LV) systolic function and coronary perfusion. However, the effects of IABP on LV diastolic function have not been comprehensively investigated. Acute diastolic dysfunction has been linked to increased morbidity and mortality. The aim of this study was to examine the influence of IABP on LV diastolic dysfunction using standard TEE derived parameters.

Methods

Intraoperative TEE was performed in 10 patients (mean age 65 ± 11 yrs) undergoing urgent coronary artery bypass graft surgery (CABG), who had received an IABP preoperatively. TEE derived measures of diastolic dysfunction included early to late transmitral Doppler inflow velocity ratio (E/A), deceleration time (Dt), pulmonary venous systolic to diastolic Doppler velocity ratio (S/D), transmitral propagation velocity (Vp), and the ratio of early to late mitral annular tissue Doppler velocities (e’/a’). Statistical analyses included the Wilcoxon Sign-Rank test, and a p<0.05 was considered significant.

Results

Transmitral inflow E/A ratios increased significantly from 0.86 to 1.07 (p < 0.05), while Dt decreased significantly from 218 to 180 ms (p < 0.05) with the use of IABP. Significant increases in Vp (34 cm/s to 43 cm/s; p < 0.05), and e’/a’ (0.58 to 0.71; p < 0.05) suggested a favourable influence of intraaortic counterpulsation on diastolic function.

Conclusion

The use of perioperative IABP significantly improves TEE derived parameters of diastolic function consistent with a favourable impact on LV relaxation in cardiac surgery patients undergoing CABG.

Is Peri-Operative Isolated Systolic Hypertension (ISH) a Cardiac Risk Factor?

We are presenting a review of Isolated Systolic Hypertension (ISH) as a cardiovascular risk factor with emphasis on the perioperative period.

Isolated systolic hypertension is associated with aging and is the most frequent subtype (65%) among patients with uncontrolled hypertension. ISH is strongly associated with increased risks of cardiac and cerebrovascular events exceeding those in comparably aged individuals with diastolic hypertension. Patients with ISH show an increase in left ventricular (LV) mass and an increase in the prevalence of left ventricular hypertrophy (LVH). These LV changes increase cardiovascular events and frequently lead to diastolic dysfunction (DD). Treatment to reduce elevated systolic blood pressure has been shown to reduce the risk of cardiovascular events.

In the perioperative setting, essential hypertension has not been found to be a significant risk factor for cardiac complications. Most of the studies were based on the definition of essential hypertension and underpowered in sample size. The significance of perioperative ISH, however, is not well studied, partly due to its recognition only fairly recently as a cardiovascular risk factor in the non-surgical setting, and partly due to the evolving definition of ISH.

Perioperative cardiac complications remain a significant problem to the healthcare system and to the patient. Although the incidence of perioperative cardiac complications is prominent in high-risk patients as defined by the Revised Cardiac Risk Index (RCRI), the bulk of the cardiac complications actually occur in low-risk group. Currently, little understanding exists on the occurrence of perioperative cardiac complications in low- risk patients. A factor such as ISH, with its known pathophysiological changes, is a potential perioperative risk factor.

We believe ISH is an under-recognized perioperative risk factor and deserves further studying. Our research group has recently been funded by the Heart Stroke Foundation (HSF) to examine ISH as a perioperative risk factor (PROMISE Study).

Preoperative diastolic function predicts the onset of left ventricular dysfunction following aortic valve replacement in high-risk patients with aortic stenosis

INTRODUCTION

Left ventricular (LV) dysfunction frequently occurs after cardiac surgery, requiring inotropic treatment and/or mechanical circulatory support. In this study, we aimed to identify clinical, surgical and echocardiographic factors that are associated with LV dysfunction during weaning from cardiopulmonary bypass (CPB) in high-risk patients undergoing valve replacement for aortic stenosis.

METHODS

Perioperative data were prospectively collected in 108 surgical candidates with an expected operative mortality >or=9%. All anesthetic and surgical techniques were standardized. Reduced LV systolic function was defined by an ejection fraction <40%. Diastolic function of the LV was assessed using standard Doppler-derived parameters, tissue Doppler Imaging (TDI) and transmitral flow propagation velocity (Vp).

RESULTS

Doppler-derived pulmonary flow indices and TDI could not be obtained in 14 patients. In the remaining 94 patients, poor systolic LV was documented in 14% (n = 12) and diastolic dysfunction in 84% of patients (n = 89), all of whom had Vp <50 cm/s. During weaning from CPB, 38 patients (40%) required inotropic and/or mechanical circulatory support. By multivariate regression analysis, we identified three independent predictors of LV systolic dysfunction: age (Odds ratio [OR] = 1.11; 95% confidence interval (CI), 1.01 to 1.22), aortic clamping time (OR = 1.04; 95% CI, 1.00 to 1.08) and Vp (OR = 0.65; 95% CI, 0.52 to 0.81). Among echocardiographic measurements, Vp was found to be superior in terms of prognostic value and reliability. The best cut-off value for Vp to predict LV dysfunction was 40 cm/s (sensitivity of 72% and specificity 94%). Patients who experienced LV dysfunction presented higher in-hospital mortality (18.4% vs. 3.6% in patients without LV dysfunction, P = 0.044) and an increased incidence of serious cardiac events (81.6 vs. 28.6%, P < 0.001).

CONCLUSIONS

This study provides the first evidence that, besides advanced age and prolonged myocardial ischemic time, LV diastolic dysfunction characterized by Vp <or= 40 cm/sec identifies patients who will require cardiovascular support following valve replacement for aortic stenosis.

Effects of on-pump and off-pump coronary artery bypass grafting on left ventricular relaxation and compliance: a comprehensive perioperative echocardiography study

AIMS

The short-term effect of coronary artery bypass grafting (CABG) on diastolic function is only moderately investigated. Furthermore, it remains unknown whether avoidance of cardioplegic arrest by an off-pump CABG procedure has advantages over on-pump procedure regarding diastolic relaxation and compliance. We investigated whether components of diastolic function would be improved the day after CABG depending on the type of the surgical procedure.

METHODS AND RESULTS

Spontaneously breathing on-pump (n = 20) and off-pump CABG (n = 12) patients underwent a comprehensive transthoracic echocardiography examination the day before and the day after elective CABG, including transmitral and pulmonary vein flow parameters, colour M-mode flow propagation velocity (Vp) and tissue Doppler assessment of the average mitral annulus diastolic velocity (Em). Isovolumic relaxation and E-wave deceleration time were corrected for heart rate (IVRTcHR and DTcHR). Left ventricular (LV) relaxation time (τ) and LV operating stiffness (LVOS) were calculated. Overall and independent from operation type and preload, CABG decreased IVRTcHR (107 ± 20 vs. 93 ± 15 ms) (P < 0.01) and τ (54 ± 10 vs. 45 ± 10 ms) (P < 0.01), increased Vp (49 ± 22 vs. 75 ± 37 cm/s) (P < 0.01), and increased Em (6.6 ± 2.0 vs. 7.3 ± 1.3 cm/s, P = 0.06), indicating improved relaxation. LVOS increased (0.13 ± 0.06 vs. 0.22 ± 0.05 mmHg/mL) (P < 0.01), compatible with an impaired compliance. A similar improvement in relaxation and impairment in compliance were observed in both groups.

CONCLUSION

Myocardial relaxation improved the day after CABG irrespective of the use of cardiopulmonary bypass with cardioplegic arrest. Impairment in compliance could not be prevented by the avoidance of cardioplegia.

Left ventricular diastolic dysfunction of the cardiac surgery patient; a point of view for the cardiac surgeon and cardio-anesthesiologist

BACKGROUND

Left ventricular diastolic dysfunction (DD) is defined as the inability of the ventricle to fill to a normal end-diastolic volume, both during exercise as well as at rest, while left atrial pressure does not exceed 12 mm Hg. We examined the concept of left ventricular diastolic dysfunction in a cardiac surgery setting.

MATERIALS AND METHODS

Literature review was carried out in order to identify the overall experience of an important and highly underestimated issue: the unexpected adverse outcome due to ventricular stiffness, following cardiac surgery.

RESULTS

Although diverse group of patients for cardiac surgery could potentially affected from diastolic dysfunction, there are only few studies looking in to the impact of DD on the postoperative outcome; Trans-thoracic echo-cardiography (TTE) is the main stay for the diagnosis of DD. Intraoperative trans-oesophageal (TOE) adds to the management. Subgroups of DD can be defined with prognostic significance.

CONCLUSION

DD with elevated left ventricular end-diastolic pressure can predispose to increased perioperative mortality and morbidity. Furthermore, DD is often associated with systolic dysfunction, left ventricular hypertrophy or indeed pulmonary hypertension. When the diagnosis of DD is made, peri-operative attention to this group of patients becomes mandatory.

Predictors of inotrope use in patients undergoing concomitant coronary artery bypass graft (CABG) and aortic valve replacement (AVR) surgeries at separation from cardiopulmonary bypass (CPB)

BACKGROUND

Left ventricular dysfunction is common after coronary artery bypass graft and valve replacement surgeries and is often treated with inotropic drugs to maintain adequate hemodynamic status. In this study, we aimed to identify the demographic, clinical, laboratory, echocardiographic and hemodynamic factors that are associated with use of inotropic drugs in patients undergoing concomitant coronary artery bypass graft and aortic valve replacement surgery.

METHODS

The study included 97 patients who had undergone concomitant coronary artery bypass graft and aortic valve replacement at Regions Hospital, University of Minnesota Medical School from January 2006 to December 2008. All data were collected retrospectively after reviewing electronic medical records. Inotropic support was defined as the use of dopamine [greater than or equal to] 5 ug/kg/min; any dose of epinephrine, norepinephrine, dobutamine, and milrinone at the separation from cardiopulmonary bypass.

RESULTS

Inotropic support was used in a total of 50 patients (52%) at the separation from cardiopulmonary bypass. Average age of the patients requiring inotropic support was 72.2 +/- 8.8 years. The study identified four significant, independent predictors of inotrope use: (1) Cardiac index [less than or equal to] 2.5 L/min/m2, (2) LVEDP [greater than or equal to] 20 mm Hg, (3) LVEF [less than or equal to] 40%, and (4) CKD stage 3 to 5.

CONCLUSION

We identified four independent risk factors for postoperative use of inotropic support in patients undergoing concomitant coronary artery bypass graft and arotic valve replacement surgery at the separation from cardiopulmonary bypass. The study results will be helpful to prospectively identify patients who will likely to require inotropic support at the separation from cardiopulmonary bypass.

[Left ventricular diastolic dysfunction. Implications for anesthesia and critical care]

Over the last two decades there has been a growing recognition that cardiac function is not solely determined by systolic but also essentially by diastolic function. Left ventricular diastolic dysfunction is characterized by an impairment of ventricular filling caused either by abnormal relaxation, an active energy consuming process or decreased compliance, which is determined by passive tissue properties of the ventricle. Doppler echocardiography, including tissue Doppler imaging, has emerged as the preferred clinical tool for the assessment of left ventricular diastolic function. Recently the importance of left ventricular diastolic function is increasingly being recognized also during the perioperative period. Newer studies have shown that after cardiopulmonary bypass there is a significant decrease in left ventricular compliance. Experimental studies have demonstrated that sepsis is associated with a decrease in both active relaxation and ventricular compliance. Initial studies are also focusing on therapeutic options for patients with isolated diastolic dysfunction.

Intraoperative assessment of diastolic function: utility of echocardiography

PURPOSE OF REVIEW

This review discusses the current and future applications of different echocardiographic modalities in evaluating diastolic function intraoperatively.

RECENT FINDINGS

Normal diastolic function is required for optimal cardiac performance. There is sufficient evidence to support the significant prevalence of preoperative diastolic dysfunction and its incidence following cardiac surgery, however controversy still exists regarding the impact of diastolic dysfunction on adverse outcomes. Echocardiography provides a relatively safe, practical and noninvasive means to evaluate perioperative diastolic function, however conventional measures may be limited by the impact of changes in heart rate, rhythm and loading conditions. Newer echocardiographic modalities are reportedly less sensitive to acute changes in loading conditions, and may therefore complement the use of conventional echocardiographic techniques in the perioperative period.

SUMMARY

The availability of effective technology for diagnosing the presence and progression of perioperative diastolic function should assist in the identification of high-risk cardiac surgical patients who may benefit from appropriate triaging and therapeutic intervention.