Eric Kruse

Hemodynamic Ramp Tests in Patients With Left Ventricular Assist Devices

OBJECTIVES This study tested whether combined invasive hemodynamic and echocardiographic ramp tests can help optimize patient management. BACKGROUND Guidelines for optimizing speed and medications in continuous flow ventricular assist device (cfLVAD) patients are mainly based on expert opinion. METHODS Thirty-five cfLVAD patients (21 HeartMate II [Thoratec, Pleasanton, California] and 14 HVAD [HeartWare International, Framingham, Massachusetts]) underwent ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP], and blood pressure) and echocardiography. Data were recorded at up to 9 speed settings. Speed changes were in steps of 400 revolutions per minute (RPM) for HeartMate II (8,000 to 12,000 RPM) and 100 RPM for HVAD (2,300 to 3,200 RPM) patients. RESULTS Only 42.9% of patients had normal CVPs and PCWPs at their original RPM settings. Going from lowest to highest speeds, cardiac output improved by 0.16 ± 0.19 l/min/step (total change 1.28 ± 1.41 l/min) and PCWP decreased by 1.23 ± 0.85 mm Hg/step (total change 9.9 ± 6.5 mm Hg). CVP and systolic blood pressure did not change significantly with RPM. RPM were adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 56% of patients. For the remainder, results indicated which type of medical management should be pursued. CONCLUSIONS Use of combined hemodynamic and echocardiographic ramp tests in patients provides objective means of optimizing RPM, and has the potential to guide medical management. It remains to be tested whether this strategy has a beneficial impact on quality of life or clinical outcomes.

Clinical hemodynamic evaluation of patients implanted with a fully magnetically levitated left ventricular assist device (HeartMate 3)

BACKGROUND The HeartMate 3 (HM3) is a Conformiteé Européenne (CE) mark-approved left ventricular assist device (LVAD) with a fully magnetically levitated rotor with features consisting of a wide range of operational speeds, wide flow paths and an artificial pulse. We performed a hemodynamic and echocardiographic evaluation of patients implanted with the HM3 LVAD to assess the speed range for optimal hemodynamic support. METHODS Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP] and blood pressure [BP]) and 3-dimensional echocardiography (3DE). Data were recorded at up to 13 speed settings. Speed changes were in steps of 100 revolutions per minute (rpm), starting at 4,600 rpm and ramping up to 6,200 rpm. RESULTS Mean original speed was 5,306 ± 148 rpm, with a majority of patients (10 of 16, 62.5%) having normal CVPs and PCWPs at their original rpm settings. Going from lowest to highest speeds, cardiac output improved at the rate of 0.08 ± 0.08 liter/min per 100 rpm (total change 1.25 ± 1.20 liters/min) and PCWP decreased at the rate of -0.48 ± 0.27 mm Hg per 100 rpm (total change -6.13 ± 3.72 mm Hg). CVP and systolic BP did not change significantly with changes in rpm. Left ventricular end-diastolic dimension (LVEDD) decreased at a rate of -0.15 ± 0.09 cm per 100 rpm. Number of rpm was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 13 (81.3%) patients. For the remaining 3 patients, medical management was pursued to optimize hemodynamic support. CONCLUSION Hemodynamic normalization of pressures was achieved in the majority of patients implanted with the HM3 pump within a narrow speed range.

Novel echocardiographic parameters of aortic insufficiency in continuous-flow left ventricular assist devices and clinical outcome

BACKGROUND The aim of this study was to evaluate the prognostic performance of novel echocardiographic (transthoracic echocardiography, or TTE) parameters for grading aortic insufficiency (AI) severity in patients with continuous-flow left ventricular assist devices (CF-LVADs). The development of AI after CF-LVAD implantation is common, although the clinical significance remains unclear. We previously described novel TTE parameters that outperformed traditional TTE parameters in grading AI severity in these patients. METHODS CF-LVAD patients with varying degrees of AI (N = 57) underwent Doppler TTE of the LVAD outflow cannula. Patients had AI severity graded by the novel parameters (systolic/diastolic velocity ratio and the diastolic acceleration of the LVAD outflow cannula) and the traditional vena contracta. The prognostic performance of novel and traditional AI parameters was determined by comparing rates of congestive heart failure re-admission, need for aortic valve intervention, urgent transplantation and death (composite end-points) for each parameter. RESULTS Grading AI severity using novel AI parameters led to reclassification of 32% of patients from trace/mild AI to moderate or greater AI (N = 18). Using traditional AI parameters, there was no difference in the occurrence of the composite end-point between the moderate or greater group and the trace/mild group (1.50 vs 1.18 events/person, p = 0.46). With the novel AI parameters, there were significantly more events in the patients with moderate or greater AI compared to those with trace/mild AI (1.57 vs 0.13 events/person, p = 0.002). Novel parameters also better predicted the need for aortic valve intervention, urgent transplantation or death than traditional methods (p = 0.024 vs p = 0.343). CONCLUSIONS In patients with CF-LVADs, traditional parameters tend to underestimate AI severity and future cardiac events. Novel AI TTE parameters are better able to discriminate AI severity and predict clinically meaningful outcomes.

Impact of Implantable Transvenous Device Lead Location on Severity of Tricuspid Regurgitation

BACKGROUND Implantable device leads can cause tricuspid regurgitation (TR) when they interfere with leaflet motion. The aim of this study was to determine whether lead-leaflet interference is associated with TR severity, independent of other causative factors of functional TR. METHODS A total of 100 patients who underwent transthoracic two-dimensional and three-dimensional (3D) echocardiography of the tricuspid valve before and after lead placement were studied. Lead position was classified on 3D echocardiography as leaflet-interfering or noninterfering. TR severity was estimated by vena contracta (VC) width. Logistic regression analysis was used to identify factors associated with postdevice TR, including predevice VC width, right ventricular end-diastolic and end-systolic areas, fractional area change, right atrial size, tricuspid annular diameter, TR gradient, device lead age, and presence or absence of lead interference. Odds ratios were used to describe the association with moderate (VC width ≥ 0.5 cm) or severe (VC width ≥ 0.7 cm) TR, separately, using bivariate and stepwise multivariate logistic regression analysis. RESULTS Forty-five of 100 patients showed device lead tricuspid valve leaflet interference. The septal leaflet was the most commonly affected (23 patients). On bivariate analysis, preimplantation VC width, right atrial size, tricuspid annular diameter, and lead-leaflet interference were significantly associated with postdevice TR. On multivariate analysis, preimplantation VC width and the presence of an interfering lead were independently associated with postdevice TR. Furthermore, the presence of an interfering lead was the only factor associated with TR worsening, increasing the likelihood of developing moderate or severe TR by 15- and 11-fold, respectively. CONCLUSION Lead-leaflet interference as seen on 3D echocardiography is associated with TR after device lead placement, suggesting that 3D echocardiography should be used to assess for lead interference in patients with significant TR.

Invasive Validation of the Echocardiographic Assessment of Left Ventricular Filling Pressures Using the 2016 Diastolic Guidelines: Head-to-Head Comparison with the 2009 Guidelines

Background: Recent American Society of Echocardiography (ASE)/European Association of Cardiovascular Imaging (EACVI) guidelines for echocardiographic evaluation of left ventricular (LV) diastolic function provide a practical, simplified diagnostic algorithm for estimating LV filling pressure. The aim of this study was to test the accuracy of this algorithm against invasively measured pressures and compare it with the accuracy of the previous 2009 guidelines in the same patient cohort. Methods: Ninety patients underwent transthoracic echocardiography immediately before left heart catheterization. Mitral inflow E/A ratio, E/e′, tricuspid regurgitation velocity, and left atrial volume index were used to estimate LV filling pressure as normal or elevated using the ASE/EACVI algorithm. Invasive LV pre‐A pressure was used as a reference, with >12 mm Hg defined as elevated. Results: Invasive LV pre‐A pressure was elevated in 40 (44%) and normal in 50 (56%) patients. The 2016 algorithm resulted in classification of 9 of 90 patients (10%) as indeterminate but estimated LV filling pressures in agreement with the invasive reference in 61 of 81 patients (75%), with sensitivity of 0.69 and specificity of 0.81. The 2009 algorithm could not definitively classify 4 of 90 patients (4.4%), but estimated LV filling pressures in agreement with the invasive reference in 64 of 86 patients (74%), with sensitivity of 0.79 and specificity of 0.70. Conclusions: The 2016 ASE/EACVI guidelines for estimation of filling pressures are more user friendly and efficient than the 2009 guidelines and provide accurate estimates of LV filling pressure in the majority of patients when compared with invasive measurements. The simplicity of the new algorithm did not compromise its accuracy and is likely to encourage its incorporation into clinical decision making. HighlightsWe tested the accuracy of the 2016 ASE/EACVI guidelines for echocardiographic evaluation of LV diastolic function in 90 patients against invasively measured pressures and compared it with the previous 2009 guidelines.The new guidelines are simpler but similarly accurate, correctly estimating LV filling pressure approximately 75% of the time.The simplicity of the new algorithm did not compromise its accuracy and is likely to encourage its incorporation into clinical decision making.

The Hemodynamic Effects of Aortic Insufficiency in Patients Supported with Continuous-Flow Left Ventricular Assist Devices

BACKGROUND The impact of aortic insufficiency (AI) on the morbidity and mortality of left ventricular assist device (LVAD) patients remains controversial. This studys aim was to assess the hemodynamics of LVAD patients with at least mild AI, at baseline and in response to device speed changes. METHODS AND RESULTS Asymptomatic LVAD patients were prospectively enrolled and underwent a hemodynamic and echocardiographic ramp study. Hemodynamics at rest and in response to device speed changes were compared between patients with at least mild AI at their baseline speed and patients without AI. Fift-five patients were enrolled in the study, and 42% had AI. The AI group had higher baseline central venous pressure (11 ± 5 vs 8 ± 5 mm Hg; P = .03), higher pulmonary capillary wedge pressure (PCWP) (16 ± 6 vs 12 ± 6 mm Hg; P = .02) and lower pulmonary artery pulsatility index (PAPI) (2.3 ± 1.3 vs 3.6 ± 2.4; P = .01). Cardiac index (CI) increased and PCWP decreased in both groups by similar degrees during the ramp study. AI worsened in 78% of patients during the ramp study. CONCLUSIONS LVAD patients with at least mild AI have increased filling pressures and reduced PAPI. Normalization of filling pressures can be achieved by increasing LVAD speed; however, this concomitantly worsens AI severity. The long-term hemodynamic consequences of this approach are unknown.

3D echocardiographic analysis of aortic annulus for transcatheter aortic valve replacement using novel aortic valve quantification software: Comparison with computed tomography

With the increasing use of transcatheter aortic valve replacement (TAVR) in patients with aortic stenosis (AS), computed tomography (CT) remains the standard for annulus sizing. However, 3D transesophageal echocardiography (TEE) has been an alternative in patients with contraindications to CT. We sought to (1) test the feasibility, accuracy, and reproducibility of prototype 3DTEE analysis software (Philips) for aortic annular measurements and (2) compare the new approach to the existing echocardiographic techniques.

Quantification of Right Ventricular Size and Function from Contrast-Enhanced Three-Dimensional Echocardiographic Images

Background: Three‐dimensional (3D) echocardiography directly assesses right ventricular (RV) volumes without geometric assumptions, despite the complex shape of the right ventricle, and accordingly is more accurate and reproducible than the two‐dimensional methodology, which is able to measure only surrogate parameters of RV function. Volumetric analysis has been hampered by frequent inability to clearly visualize RV endocardium, especially the RV free wall, in 3D echocardiographic images. The aim of this study was to test the hypothesis that RV contrast enhancement during 3D echocardiographic imaging would improve the accuracy of RV volume and function analysis. Methods: Thirty patients with a wide range of RV size and function and image quality underwent transthoracic 3D echocardiography with and without contrast enhancement and cardiovascular magnetic resonance imaging on the same day. RV end‐diastolic and end‐systolic volumes and ejection fraction were measured from contrast‐enhanced and nonenhanced 3D echocardiographic images and compared with cardiovascular magnetic resonance reference values using linear regression and Bland‐Altman analyses. Blinded repeated measurements were performed to assess measurement variability. Results: RV contrast enhancement was feasible in all patients. RV volumes obtained both with and without contrast enhancement correlated highly with cardiovascular magnetic resonance (end‐diastolic volume, r = 0.90 and r = 0.92; end‐systolic volume, r = 0.92 and r = 0.94, respectively), but the correlation for ejection fraction was better with contrast (r = 0.87 vs r = 0.70). Biases were smaller with contrast for all three parameters (end‐diastolic volume, −16 ± 23 vs −36 ± 25 mL; end‐systolic volume, −10 ± 16 vs −23 ± 18 mL; ejection fraction, −0.7 ± 5.5% vs −2.7 ± 8.1% of the mean measured values), reflecting improved accuracy. Also, measurement reproducibility was improved by contrast enhancement. Conclusions: Contrast enhancement improves the visualization of RV endocardial borders, resulting in more accurate and reproducible 3D echocardiographic measurements of RV size and function. This approach may be particularly useful in patients with suboptimal image quality. HighlightsWe hypothesized that contrast enhancement during 3D echocardiographic imaging would improve the accuracy of RV volume and function analysis.This hypothesis was tested by comparing measurements obtained from nonenhanced and contrast‐enhanced images against cardiac magnetic resonance reference images.Contrast enhancement improved the visualization of RV endocardial borders, resulting in more accurate and more reproducible measurements.This approach may be particularly useful in patients with suboptimal image quality. Abbreviations: 2D = Two‐dimensional; 3D = Three‐dimensional; CMR = Cardiovascular magnetic resonance; EDV = End‐diastolic volume; ESV = End‐systolic volume; LV = Left ventricular; RV = Right ventricular; RVEF = Right ventricular ejection fraction; RVOT = Right ventricular outflow tract.

Screening for Outflow Cannula Malfunction of Left Ventricular Assist Devices (LVADs) With the Use of Doppler Echocardiography: New LVAD-Specific Reference Values for Contemporary Devices

BACKGROUND Echocardiographic assessment of left ventricular assist devices (LVADs) is used as a screening tool to evaluate the integrity and mechanics of the pump and circuit. We aimed to 1) establish the normal range and upper reference limit of peak velocity of the outflow cannula for the modern era of LVADs and 2) assess the clinical performance of the currently cited and newly proposed reference limits in patients with continuous-flow LVADs as a screening tool for cannula malfunction. METHODS LVAD outflow peak CW velocities were measured with the use of Doppler transthoracic echocardiography (TTE) in 57 patients with LVADs (44 with Heartmate II (HM2), 13 with Heartware (HW)). The average velocity and the upper and lower normal reference limits (defined as ±2 standard deviations from the mean) for each LVAD type was calculated. The upper reference limit was then used as a screening threshold for cannula malfunction. RESULTS The average outflow cannula peak velocity for the normal HM2 cohort was 1.86 ± 0.44 m/s with upper and lower reference limits of 2.73 m/s and 0.98 m/s, respectively. The average outflow cannula peak velocity for the normal HW cohort was 2.36 ± 0.53 m/s with upper and lower reference limits of 3.42 m/s and 1.3 m/s, respectively, which was significantly higher than the HM2 cohort (P = .004). CONCLUSIONS In both HM2 and HW LVADs, the average peak outflow velocity and reference limit for the normal population, as measured by Doppler TTE, was markedly higher than the currently used LVAD reference limits of 2 m/s and are significantly different between devices. Patients with peak outflow velocities above our upper reference limits should be evaluated for LVAD outflow cannula malfunction.

Load Dependency of Left Atrial Strain in Normal Subjects

Background: Left atrial (LA) longitudinal strain is a novel parameter used for the evaluation of LA function, with demonstrated prognostic value in several cardiac diseases. However, the extent of load dependency of LA strain is not well known. The aim of this study was to evaluate the impact of acute changes in preload on LA strain, side by side with LA volume, in normal subjects. Methods: Twenty‐five healthy volunteers (13 men; mean age, 31 ± 2 years) were prospectively enrolled, who underwent two‐dimensional and three‐dimensional echocardiographic imaging during acute stepwise reductions in preload using a tilt maneuver: baseline at 0°, followed by 40° and 80°. Left ventricular and LA size and function parameters were measured using standard methodology, and LA strain‐time curves were obtained using speckle‐tracking software (TomTec), resulting in reservoir, conduit, and contractile strain components. All parameters were compared among the three loading conditions using one‐way analysis of variance for repeated measurements. Results: Although there were no significant changes in blood pressure, heart rate increased significantly with tilt. As expected, LA volumes, left ventricular volumes, and left ventricular ejection fraction, as well as E wave, A wave, and e′ significantly decreased with progressive inclination. In parallel, LA reservoir, conduit, and contractile strain values decreased with reduction in preload (reservoir: 42.9 ± 3.9% to 27.5 ± 3.8%, P < .001; conduit: 29.3 ± 2.7% to 20.2 ± 5.0%, P < .001; contractile: 13.6 ± 2.9% to 7.3 ± 3.5%, P < .001). Paired post hoc analysis showed that all LA strain values were significantly different among all three tilt phases. Of note, percentage change in LA reservoir strain was significantly smaller than that in LA maximum volume. Conclusions: In normal subjects, LA strain is preload dependent but to a lesser degree than LA volume. This difference underscores the relative advantage of LA strain over maximum volume, when LA assessment is used as part of the diagnostic paradigm. HIGHLIGHTSWe studied the impact of preload changes on LA strain and volume in normal subjects.LA strain is preload dependent, but to a lesser degree than LA volume.Left atrial strain should be interpreted while taking into account loading conditions.