Jerry D. Estep

The Role of Echocardiography and Other Imaging Modalities in Patients With Left Ventricular Assist Devices

Recent advances in the field of left ventricular device support have led to an increased use of left ventricular assist devices (LVADs) in patients with end stage heart disease. The primary imaging modality to monitor patients with LVADs has been echocardiography. The purpose of this review is to highlight the clinical role of echo and other noninvasive imaging modalities in the assessment of cardiac structure and function in patients with pulsatile and continuous flow LVADs. In addition, we discuss the role of imaging with emphasis on echo to detect LVAD dysfunction and device related complications.

Echocardiographic Evaluation of Hemodynamics in Patients With Decompensated Systolic Heart Failure

Background— Doppler echocardiography is currently applied for the assessment of left ventricular and right ventricular hemodynamics in patients with cardiovascular disease. However, there are conflicting reports about its accuracy in patients with unstable decompensated heart failure. The objective of this study was to evaluate the accuracy of the technique in patients with unstable heart failure. Methods and Results— Consecutive patients with decompensated heart failure had simultaneous assessment of left ventricular and right ventricular hemodynamics invasively and by Doppler echocardiography. In 79 patients, the noninvasive measurements of stroke volume (r=0.83, P<0.001), pulmonary artery systolic (r=0.83, P<0.001) and diastolic pressure (r=0.51, P=0.009), and mean right atrial pressure (r=0.85, P<0.001) all had significant correlations with invasively acquired measurements. Several Doppler indices had good accuracy in identifying patients with pulmonary capillary wedge pressure >15 mm Hg (area under the curve, 0.86 to 0.92). The recent American Society of Echocardiography/European Association of Echocardiography guidelines were highly accurate (sensitivity, 98%; specificity, 91%) in identifying patients with increased wedge pressure. In 12 repeat studies, Doppler echocardiography readily detected the changes in mean wedge pressure (r=0.75, P=0.005) as well as changes in pulmonary artery systolic pressure and mean right atrial pressure. Conclusions— Doppler echocardiography provides reliable assessment of right and left ventricular hemodynamics in patients with decompensated heart failure.

Reversal of secondary pulmonary hypertension by axial and pulsatile mechanical circulatory support.

BACKGROUND Pulmonary hypertension associated with chronic congestive heart failure posses a significant risk of morbidity and death after heart transplantation. Isolated observations suggest that chronic ventricular unloading may lead to normalization of pulmonary pressures and thus render a patient likely to be a heart transplant candidate. METHODS This study is a retrospective analysis of 9 heart failure patients with secondary pulmonary hypertension (transpulmonary gradient [TPG] > 15 mm/Hg). Two were treated with a pulsatile left ventricular assist device (LVAD) and 7 with an axial-flow LVAD. RESULTS After LVAD support, mean pulmonary artery pressure decreased from 39 +/- 7 to 31 +/- 5 mm Hg, and the TPG decreased from 19 +/- 3 to 13 +/- 4 mm Hg (p < 0.01). The 1-year Kaplan-Meier survival curve for patients with pre-LVAD TPG > 15 mm Hg vs those with TPG < 15 mm Hg showed no difference in survival (p = 0.6). This finding was supported by analysis of a large multi-institutional cohort obtained from the Organ Procurement and Transplantation Network database, where no differences in survival were found in the same groups. CONCLUSIONS Pulmonary hypertension that is secondary to congestive heart failure, as defined by a TPG > 15 mm Hg can be reversed by the use of pulsatile and axial-flow LVADs; furthermore, post-transplant survival for patients with secondary pulmonary hypertension treated with an LVAD was no different than for those without pulmonary hypertension who received LVAD support.

Echocardiography in the Management of Patients with Left Ventricular Assist Devices: Recommendations from the American Society of Echocardiography.

Raymond F. Stainback, MD, FASE, Chair, Jerry D. Estep, MD, FASE, Co-Chair, Deborah A. Agler, RCT, RDCS, FASE, Emma J. Birks, MD, PhD, Merri Bremer, RN, RDCS, EdD, FASE, Judy Hung, MD, FASE, James N. Kirkpatrick, MD, FASE, Joseph G. Rogers, MD, and Nishant R. Shah, MD, MSc, Houston, Texas; Cleveland, Ohio; Louisville, Kentucky; Rochester, Minnesota; Boston, Massachusetts; Philadelphia, Pennsylvania; and Durham, North Carolina

Increased right-to-left ventricle diameter ratio is a strong predictor of right ventricular failure after left ventricular assist device.

BACKGROUND Predictors of right ventricular failure (RVF) in patients with left ventricular assist devices (LVADs) have not been fully elucidated and are comprised mostly of clinical variables. We evaluated echocardiographic parameters associated with adverse outcomes in this population. METHODS Transthoracic echocardiograms (TTEs) before continuous-flow LVAD implantation were analyzed in 109 patients. Twenty-six 2-dimensional and Doppler parameters were assessed for their association with the primary outcome of 30-day RVF, defined as a requirement of an RV assist device or ≥ 14 consecutive days of inotropic support, and the secondary composite outcome of 30-day death or RVF. Multivariate analysis adjusted for known clinical risk prediction models was performed. RESULTS Overall, 25 (22.9%) and 27 (24.8%) patients reached the primary and secondary end-points, respectively. An increased RV/LV diameter ratio was the only TTE variable independently associated with both the primary (odds ratio [OR] = 5.40; 95% confidence interval [CI] 2.40 to 12.40; p = 0.012) and secondary (OR = 2.70; 95% CI 1.06 to 6.22; p = 0.03) outcomes after multivariate analysis. Scatterplot analysis with regression determined the optimal cut-off value for RV/LV diameter to be 0.75. Based on receiver operating characteristic curves, an increased RV/LV diameter ratio provided an additional predictive value to clinical risk scores. CONCLUSIONS A TTE-measured RV/LV diameter ratio of ≥0.75 is independently associated with a higher risk for RVF in patients with continuous-flow LVAD. When used alone, this simple, easily derived, practical echocardiographic measurement has a predictive value equivalent to known clinical risk scores, whereas their combination provides stronger risk prediction for adverse outcomes.

Percutaneous Placement of an Intra-Aortic Balloon Pump in the Left Axillary/Subclavian Position Provides Safe, Ambulatory Long-Term Support as Bridge to Heart Transplantation

OBJECTIVES This study evaluated the feasibility, tolerability, and efficacy of a strategy for percutaneous intra-aortic balloon pump (IABP) placement through the left axillary-subclavian artery to provide mechanical circulatory support in patients with end-stage heart failure as a bridge to heart transplantation. BACKGROUND The transfemoral approach to IABP placement is associated with major disadvantages, including the risk for infection and limitation of patient mobility in those requiring extended support. METHODS We developed a percutaneous technique for placing IABPs in the left axillary artery that permits upright sitting and ambulation. We performed a retrospective review of data from patients who had undergone left axillary IABP implantation between 2007 and 2012. RESULTS Fifty patients who received a left axillary IABP as a bridge to transplantation were identified, of whom 42 (84%) underwent heart or heart-multiorgan transplantation. Cumulative survival on IABP support was 92%, and post-transplant 90-day survival was 90%. Median duration of support was 18 days. Four of 50 patients (8%) died while on IABP support, and 3 (6%) received greater mechanical circulatory support. Four patients (8%) had clinically significant thromboembolic or bleeding events without long-term sequelae. The most common minor adverse event was IABP malposition, in 22 patients (44%). Prolonged IABP support in the heart-transplantation cohort was associated with significant improvements in mean pulmonary artery pressure and in creatinine and total bilirubin concentrations. CONCLUSIONS Percutaneous insertion of an IABP through the left axillary artery is a feasible and relatively well-tolerated strategy to bridge patients with end-stage heart failure to heart transplantation. This form of mechanical-device treatment permits upright sitting and ambulation in those requiring extended support.

Two-Year Outcomes with a Magnetically Levitated Cardiac Pump in Heart Failure

Background In an early analysis of this trial, use of a magnetically levitated centrifugal continuous‐flow circulatory pump was found to improve clinical outcomes, as compared with a mechanical‐bearing axial continuous‐flow pump, at 6 months in patients with advanced heart failure. Methods In a randomized noninferiority and superiority trial, we compared the centrifugal‐flow pump with the axial‐flow pump in patients with advanced heart failure, irrespective of the intended goal of support (bridge to transplantation or destination therapy). The composite primary end point was survival at 2 years free of disabling stroke (with disabling stroke indicated by a modified Rankin score of >3; scores range from 0 to 6, with higher scores indicating more severe disability) or survival free of reoperation to replace or remove a malfunctioning device. The noninferiority margin for the risk difference (centrifugal‐flow pump group minus axial‐flow pump group) was ‐10 percentage points. Results Of 366 patients, 190 were assigned to the centrifugal‐flow pump group and 176 to the axial‐flow pump group. In the intention‐to‐treat population, the primary end point occurred in 151 patients (79.5%) in the centrifugal‐flow pump group, as compared with 106 (60.2%) in the axial‐flow pump group (absolute difference, 19.2 percentage points; 95% lower confidence boundary, 9.8 percentage points [P<0.001 for noninferiority]; hazard ratio, 0.46; 95% confidence interval [CI], 0.31 to 0.69 [P<0.001 for superiority]). Reoperation for pump malfunction was less frequent in the centrifugal‐flow pump group than in the axial‐flow pump group (3 patients [1.6%] vs. 30 patients [17.0%]; hazard ratio, 0.08; 95% CI, 0.03 to 0.27; P<0.001). The rates of death and disabling stroke were similar in the two groups, but the overall rate of stroke was lower in the centrifugal‐flow pump group than in the axial‐flow pump group (10.1% vs. 19.2%; hazard ratio, 0.47; 95% CI, 0.27 to 0.84, P=0.02). Conclusions In patients with advanced heart failure, a fully magnetically levitated centrifugal‐flow pump was superior to a mechanical‐bearing axial‐flow pump with regard to survival free of disabling stroke or reoperation to replace or remove a malfunctioning device. (Funded by Abbott; MOMENTUM 3 ClinicalTrials.gov number, NCT02224755.)

Mechanical Unloading Promotes Myocardial Energy Recovery in Human Heart Failure

Background—Impaired bioenergetics is a prominent feature of the failing heart, but the underlying metabolic perturbations are poorly understood. Methods and Results—We compared metabolomic, gene transcript, and protein data from 6 paired samples of failing human left ventricular tissue obtained during left ventricular assist device insertion (heart failure samples) and at heart transplant (post-left ventricular assist device samples). Nonfailing left ventricular wall samples procured from explanted hearts of patients with right heart failure served as novel comparison samples. Metabolomic analyses uncovered a distinct pattern in heart failure tissue: 2.6-fold increased pyruvate concentrations coupled with reduced Krebs cycle intermediates and short-chain acylcarnitines, suggesting a global reduction in substrate oxidation. These findings were associated with decreased transcript levels for enzymes that catalyze fatty acid oxidation and pyruvate metabolism and for key transcriptional regulators of mitochondrial metabolism and biogenesis, peroxisome proliferator-activated receptor &ggr; coactivator 1&agr; (PGC1A, 1.3-fold) and estrogen-related receptor &agr; (ERRA, 1.2-fold) and &ggr; (ERRG, 2.2-fold). Thus, parallel decreases in key transcription factors and their target metabolic enzyme genes can explain the decreases in associated metabolic intermediates. Mechanical support with left ventricular assist device improved all of these metabolic and transcriptional defects. Conclusions—These observations underscore an important pathophysiologic role for severely defective metabolism in heart failure, while the reversibility of these defects by left ventricular assist device suggests metabolic resilience of the human heart.

A simplified echocardiographic technique for detecting continuous-flow left ventricular assist device malfunction due to pump thrombosis.

BACKGROUND Malfunction of a continuous-flow left ventricular assist device (CF-LVAD) due to device thrombosis is a potentially life-threatening event that currently presents a diagnostic challenge. We aimed to propose a practical echocardiographic assessment to diagnose LVAD malfunction secondary to pump thrombosis. METHODS Among 52 patients implanted with a CF-LVAD from a single center who underwent echocardiographic pump speed-change testing, 12 had suspected pump thrombosis as determined by clinical, laboratory, and/or device parameters. Comprehensive echocardiographic evaluation was performed at baseline pump speed and at each 1,000-rpm interval from the low setting of 8,000 rpm to the high setting of 11,000 rpm in 11 of these patients. RESULTS Receiver operating characteristic curves and stepwise logistic regression analyses showed that the best diagnostic parameters included changes in the LV end-diastolic diameter (<0.6 cm), aortic valve opening time (<80 msec), and deceleration time of mitral inflow (<70 msec) from lowest to highest pump speed. One parameter was predictive of pump malfunction, with 100% sensitivity and 89% specificity, whereas 2 of 3 parameters increased the sensitivity to 100% and specificity to 95%. CONCLUSIONS The 3 echocardiographic variables of measured changes in LV end-diastolic diameter, aortic valve opening time, and deceleration time of mitral inflow between the lowest (8,000 rpm) and highest pump speed settings (11,000 rpm) during echo-guided pump speed-change testing appear highly accurate in diagnosing device malfunction in the setting of pump thrombosis among patients supported with CF-LVAD. Further investigation is warranted to create and validate a prediction score.

Comprehensive review and suggested strategies for the detection and management of aortic insufficiency in patients with a continuous-flow left ventricular assist device

From the Department of Cardiology, St. Vincent Heart Center of Indiana, Indianapolis, Indiana; Division of Cardiac Surgery, Peter Munk Cardiac Centre, Toronto, Ontario, Canada; Department of Surgery, University of Rochester, Rochester, New York; Department of Cardiothoracic Surgery, Abbott Northwestern Hospital, Minneapolis, Minnesota; Bioengineering Program, San Diego State University, San Diego, California; Division of Cardiology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York; and the Department of Cardiology, Houston Methodist Hospital, Houston, Texas.