Evaluation of Left Ventricular Contractile Function Using Noninvasively Determined Single-beat End-systolic Elastance in Mitral Regurgitation: Experimental Validation and Clinical Application

Ventricular Arterial Coupling: A Novel Echocardiographic Risk Factor for Disease Progression in Pediatric Dilated Cardiomyopathy

In adult heart failure (HF) patients, a higher ventricular arterial (VA) coupling ratio measured non-invasively is associated with worse HF prognosis and response to treatment. There are no data regarding the relationship of VA coupling to outcome in pediatric dilated cardiomyopathy (DCM) patients. We investigated the association of VA coupling ratio with worse outcome (mechanical circulatory support, transplant, or death) in 48 children with DCM and 97 age-gender matched controls. Mean age at presentation was 9 ± 7 years; DCM patients had a higher arterial elastance (3.8 ± 1.7 vs 2.7 ± 0.7 respectively p = 0.001), a lower LV elastance (1.1 ± 0.65 vs 4.5 ± 1.4, respectively p = 0.001) and higher VA coupling ratio (5.0 ± 3.9 vs 0.34 ± 0.14, respectively p = 0.001). Outcome events occurred in 27/48 (56%) patients. Patients with an outcome event had a higher NYHA class (p = 0.001), lower LV elastance (0.8 ± 0.47 vs 1.6 ± 0.57, respectively p = 0.001), higher arterial elastance (4.5 ± 1.8 vs 2.9 ± 1.1, respectively p = 0.002), and a higher VA coupling ratio (7.1 ± 3.8 vs 2.2 ± 1.5, respectively p = 0.001) compared to those without. In a multivariate CART analysis, VA coupling was the top and only discriminator of poor outcome. In conclusion, a higher VA coupling ratio is associated with worse outcome in pediatric patients with DCM. VA coupling is promising as a bedside analysis tool that may provide insight into the mechanisms of HF in pediatric DCM and identify potential targets for therapy.

The characteristics of a porcine mitral regurgitation model

The porcine mitral regurgitation (MR) model is a common cardiovascular animal model. Standardized manufacturing processes can improve the uniformity and success rate of the model, and systematic research can evaluate its potential use. In this study, 17 pigs were divided into an experimental group (n=11) and a control group (n=6). We used a homemade retractor to cut the mitral chordae via the left atrial appendage to establish a model of MR; the control group underwent a sham surgery. The model animals were followed for 30 months after the surgery. Enlargement and fibrosis of the left atrium were significant in the experimental group compared with those in the control group, and left atrial systolic function decreased significantly. In addition, model animals showed preserved left ventricular systolic function. There were no differences in left atrial potential or left ventricular myocardial fibrosis between the two groups. Atrial fibrillation susceptibility in the experimental group was higher than that in the control group. Our method enables the simple and effective production of a MR model with severe reflux that can be used for pathophysiological studies of MR, as well as for the development of preclinical surgical instruments and their evaluation. This model could also be used to study atrial fibrillation and myocardial fibrosis but is not suitable for studies of heart failure.

Early Hemodynamic Improvement after Percutaneous Mitral Valve Repair Evaluated by Noninvasive Pressure-Volume Analysis

BACKGROUND

Mitral regurgitation represents a volume load on the left ventricle leading to congestion and symptoms of heart failure. The aim of this study was to characterize early hemodynamic adaptions after percutaneous mitral valve (MV) repair.

METHODS

Forty-six consecutive patients with symptomatic high-grade MV insufficiency (mean age, 72 years; 54% men) were prospectively included in the study and examined before and after successful catheter-based clip implantation. Seventy percent of patients had secondary mitral regurgitation. Noninvasive pressure-volume loops were reconstructed from echocardiography with simultaneous blood pressure measurements.

RESULTS

MV repair reduced left ventricular end-diastolic volume index from 87 ± 41 to 80 ± 40 mL/m(2) (P < .0001). End-systolic volume index was 55 ± 37 mL/m(2) before versus 54 ± 37 mL/m(2) after repair (P = .52). Hence, total stroke volume decreased from 60 ± 23 to 49 ± 16 mL (P < .0001), as did total ejection fraction (from 41 ± 14% to 37 ± 13%, P = .002) and global longitudinal strain (from -11 ± 4.9% to -9.1 ± 4.4%, P = .0001). Forward stroke volume, forward ejection fraction, and forward cardiac output remained constant (43 ± 12 mL vs 42 ± 11 mL, 33 ± 17% vs 35 ± 18%, and 3.2 ± 0.9 L/min vs 3.4 ± 0.8 L/min, respectively). Parameters of left ventricular contractility (end-systolic elastance and peak power index) and measurements of afterload (arterial elastance, end-systolic wall stress, and total peripheral resistance) were similar before and after MV repair. Forward ejection fraction correlated more strongly with end-systolic elastance (r = 0.61, P < .0001) than did total ejection fraction (r = 0.35, P = .0007) or global longitudinal strain (r = -0.38, P = .0002). Total mechanical energy (pressure-volume area) decreased from 10,903 ± 4,410 to 9,124 ± 2,968 mm Hg × mL (P = .0007) because of reduced stroke work (5,546 ± 2,241 mm Hg × mL vs 4,414 ± 1,412 mm Hg × mL, P < .0001). At 3 months, symptom status had improved (76% of patients in New York Heart Association classes I and II), and 97% of patients had mitral regurgitation grade ≤2+.

CONCLUSIONS

Left ventricular contractility and forward cardiac output remained unchanged after percutaneous MV repair despite decreases in total ejection fraction and global longitudinal strain. The left ventricle was unloaded through reduced end-diastolic volume. Thus, MV repair is associated with an improved hemodynamic state in noninvasive pressure-volume analysis.

Validation of Noninvasive Measures of Left Ventricular Mechanics in Children: A Simultaneous Echocardiographic and Conductance Catheterization Study

BACKGROUND

The accuracy of echocardiography in evaluating left ventricular contractility has not been validated in children. The objective of this study was to compare echocardiographic measures of contractility with those derived from pressure-volume loop (PVL) analysis in children.

METHODS

Patients with relatively normal loading conditions undergoing routine left heart catheterization were prospectively enrolled. PVLs were obtained via conductance catheters. The gold-standard measure of contractility, end-systolic elastance (Ees), was obtained via balloon occlusion of one or both vena cavae. Echocardiograms were performed immediately after PVL analysis under the same anesthetic conditions. Single-beat estimations of echocardiographic Ees were calculated using four different methods. These estimates were calculated using a combination of noninvasive blood pressure readings, ventricular volumes derived from three-dimensional echocardiography, and Doppler time intervals.

RESULTS

Of 24 patients, 18 patients were heart transplant recipients, and six patients had small patent ductus arteriosus or small coronary fistulae. The mean age was 9.1 ± 5.6 years. The average invasive Ees was 3.04 ± 1.65 mm Hg/mL. Invasive Ees correlated best with echocardiographic Ees by the method of Tanoue (r = 0.85, P < .01), with a mean difference of -0.07 mm Hg/mL (95% limits of agreement, -2.0 to 1.4 mm Hg/mL).

CONCLUSIONS

Echocardiographic estimates of Ees correlate well with gold-standard measures obtained via conductance catheters in children with relatively normal loading conditions. The use of these noninvasive measures in accurately assessing left ventricular contractility appears promising and merits further study in children.

Left ventricular function in gestational hypertension: serial echocardiographic study

BACKGROUND

Gestational hypertension (GH) is associated with hemodynamic changes, and alterations of systolic and diastolic left ventricular (LV) function. However, the magnitude and pattern of changes of different parameters of LV function and contractility in this patient population have not been fully clarified.

METHODS

Thirty-five pregnant women with GH underwent three echocardiographic examinations, in second and third trimester of pregnancy, and 1 month after delivery. Twelve normotensive pregnant women served as gestational age-matched controls. Hemodynamic parameters and standard indexes of LV systolic and diastolic function were analyzed. Additionally, we have measured peak systolic velocity of mitral annulus (S'), end-systolic elastance (Ees), and early transmitral to early lengthening velocity of mitral annulus ratio (E/E') as parameters of longitudinal function, contractility, and filling, respectively.

RESULTS

Women with GH had initially higher body weight, blood pressure, and heart rate (P < 0.005, P < 0.0001, and P = 0.011, respectively). Temporal analysis of different echocardiographic parameters revealed increase in wall thickness from baseline to second measurement, with consequential increase in LV mass in women with GH (P = 0.014 for septum, P = 0.010 for posterior wall, and P = 0.09 for LV mass). No significant changes of LV volumes, ejection fraction (EF), transmitral flow parameters, S', Ees, and E/E' were observed throughout the follow-up in both groups (P = nonsignificant for all). Importantly, pattern of changes was similar in both groups for all examined parameters (P = nonsignificant between groups, for all).

CONCLUSIONS

It appears that changes of LV longitudinal function, filling, and contractility during pregnancy are not significant and not influenced by GH.

Detection of left ventricular dysfunction with Tei index in normal ejection fraction patients with mitral regurgitation before mitral valve surgery

Ejection fraction (EF) was not considered a reliable parameter of left ventricular (LV) function and was normal in most patients with chronic mitral regurgitation (MR), whereas LV dysfunction expressed as decreased EF was often shown after mitral valve surgery. This study sought the ability of the Tei index to detect latent LV dysfunction in patients with MR and apparently normal EF. One hundred eight patients with apparently normal EF (EF > or =50%) and chronic severe MR who underwent mitral valve repair were investigated. EF was significantly decreased after surgery and LV dysfunction (EF <50%) was shown in 37 patients (34% of all patients). The preoperative Tei index significantly correlated with postoperative EF in all patients (r = -0.64, p <0.0001) and asymptomatic patients (n = 44; r = -0.57, p <0.0001). By setting the preoperative Tei index >0.5 to predict postoperative EF <50%, this index had sensitivity, specificity, and accuracy of 89%, 85%, and 86% in all patients and 80%, 85%, and 84% in asymptomatic patients, respectively. In conclusion, a preoperative Tei index >0.5 allowed prediction of postoperative LV dysfunction in patients with MR with apparently normal EF. Thus, earlier surgery is recommended in asymptomatic patients with MR with normal EF, but Tei index >0.5.