Aortic Valve Closure Research Articles

Listening to heart sounds through the pressure waveform.

Non-invasive diagnostic modalities are integral to cardiovascular care; however, current systems primarily measure peripheral pressure, limiting the breadth of cardiovascular prognostication. We report a novel approach for extracting left side heart sounds using a brachial cuff device. The technique leverages brachial cuff device enhanced signal resolution to capture pressure fluctuations generated by cardiohemic system vibrations, the sound pressure waveform. We analyze left heart catheterization data alongside simultaneous brachial cuff device measurements to correlate sound pressure waveform features with left ventricle (LV) contractility. The extracted sound pressure waveform reveals two prominent oscillatory wave packets, termed WP1 and WP2, originating from cardiac structure vibrations associated with LV contractions and relaxation. We demonstrate that WP1 originates from LV contraction during systolic blood ejection through the aortic valve (AV) and is correlated with LV isovolumetric contraction, clinically measured by LV dPdt-max (Pearson-R = 0.65, p < 0.001). Additionally, we show that WP2 comes from LV elongation required for blood flow deceleration at the end of systole, causing AV closure, and is correlated with LV isovolumetric relaxation, measured by LV ndPdt-max (Pearson-R = 0.55, p < 0.001). These findings highlight the value of cuff sound pressure waveforms in providing insights about dynamic coupling of the LV-Aorta complex for non-invasive assessment of LV contractility.

Subaortic Pannus Causing Complete Outlet Obstruction After Bioprosthetic Aortic Valve Replacement in a Patient with Left Ventricular Assist Device: A Case Report

Abstract Background Subaortic pannus formation complicates bioprosthetic aortic valve(AV) replacement. We report an extreme case in a continuous-flow left-ventricular-assist-device(LVAD) patient. Case Summary A 49-year-old Caucasian female with dilated cardiomyopathy was bridged-to-transplant with a HeartWare ventricular-assist-device(HVAD). Duration of support was prolonged, 6-years and 7-months, due to allosensitisation requiring desensitisation. Pump thrombosis occurred 2-years and 4-months post-LVAD requiring alteplase thrombolysis. The patient underwent bioprosthetic AV replacement 3-years and 10-months post-LVAD for symptomatic aortic incompetence. Transthoracic echocardiography(TTE) performed 1-year and 2-years post-bioprosthetic AV replacement repeatedly demonstrated an AV closed during all cardiac cycles without incompetence and nil flow through the left-ventricular-outflow-tract(LVOT). Following transplant, analysis of explanted heart revealed a fused AV. A pannus adherent to the underside of the AV had formed across the entire AV outlet, with complete obliteration of LVOT. This subaortic pannus was not visualised on previous TTE. Histologically, the pannus consisted of hypocellular fibrous tissue with chronic inflammatory cells, spindle histiocytes and myofibroblasts scattered throughout the loose fibromyxoid stroma, the latter highlighted on CD68 immunohistochemical stain(IHC). Partial endothelialisation on the pannus surface was highlighted on ERG &amp; CD31 IHC. Neither calcification, nor signs of acute inflammation were noted. In contrast to previous cases, there was no evidence of associated thrombus macroscopically or microscopically. Discussion Prolonged LVAD support may facilitate subaortic pannus following bioprosthetic AV replacement due to AV closure and altered transvalvular flow. Due to the parallel LVAD circulation, subaortic pannus may develop asymptomatically, without haemodynamic compromise, allowing progression to total LVOT obstruction. This requires consideration prior to LVAD explantation in bridge-to-recovery patients.

Evaluating the performance of automatic wave speed estimators of natural shear waves to assess myocardial stiffness

Abstract Introduction Cardiac Shear Wave Elastography is an emerging non-invasive technique using ultrafast echocardiographic imaging. Natural shear waves (SW) occur after mitral valve closure (MVC) and aortic valve closure (AVC), and their propagation velocities are directly related to myocardial stiffness. However, the current assessment of SW velocities lacks a gold standard method, and relies on manual measurements with their inherent variability. Purpose To explore new automated methods for shear wave velocity estimates, aiming to achieve greater accuracy, less variability, and high feasibility. Methods To visualize shear waves, anatomical M-modes were drawn (4±1 cm) along ventricular septum in parasternal long axis views (PLAX), acquired with high-frame-rate echocardiography (1055±159 Hz). M-modes were colour coded for tissue acceleration. SWs appear as tilted green bands after MVC &amp; AVC, the slope of which represents the SW propagation velocity. One hundred-twenty different slopes from healthy volunteers (n=67) and patients (n=53) were measured manually and with 9 different automatic methods. All automatic methods were initiated by indicating the approximate position of the shear wave in the M-mode with a mouse click of the user. Measurements were repeated three times to assess measurement reproducibility. (figure 1, A). In order to determine the influence of display settings, three different acceleration colour scales were tested (0.5, 1, 2 m/s²). (Figure 1, B). Failure of correctly identifying shear waves was counted to assess feasibility. Due to the lack of a gold standard, manual measurements of an experienced reader served as reference. Results Three of nine automatic methods: Radon Transformation (RT), Regression Segmentation Maximum value (RM), Regression Segmentation Weighted Maximum (RMW), revealed the least variability with repeated measurements (0.0±0.0 m/s for all) and colour scales (0.0±0.0, 0.1±0.2 and 0.1±0.2 m/s, resp.). Those three methods showed moderate to good agreement (r=0.66, ICC 0.77 [CI 0.64- 0.85]; r= 0.67, ICC 0.75 [CI 0.50 -0.86]; and r= 0.77, ICC 0.85 [CI 0.73-0.90], resp.) with manual measurements (r=0.96, ICC 0.98 [CI 0.97- 0.99] (figure 2). Conclusion RT, RM, and RMW showed a good reproducibility while RMW showed the best agreement with manual measurements. Our data suggest, that the RMW method could offer an objective alternative for SW velocity estimations. Further research is needed to explore their applicability in clinical scenarios.

Mechanical wave velocities by clutter filter wave imaging detects myocardial dysfunction in acute coronary syndrome

Abstract Background/introduction Mechanical waves within the myocardium arising from physiologic events in the cardiac cycle such as the atrial kick (AK), mitral valve closure (MVC) and aortic valve closure (AVC) offer insight to tissue stiffness and can be measured by high frame rate echocardiography. Purpose To investigate the feasibility of measuring mechanical wave velocities in the left ventricle by clutter filter wave imaging (CFWI) and its potential for detecting regional myocardial dysfunction in patients with acute coronary syndrome. Methods We examined 60 patients (66±9 years of age, 72% male) with acute coronary syndrome by high frame rate echocardiography after revascularisation, imaging the left ventricle from the parasternal long axis view and three apical projections. Intrinsic mechanical waves generated by the AK, MVC and AVC were analysed off-line by CFWI of all walls using custom software (PyMWI) on 2000 frames of in-phase and quadrature component data per view extracted from a Vivid E95 scanner. Results We analysed a total number of 2372 waves recorded with a frame rate of 1180 (1134-1199) frames per second. The feasibility for measuring AK waves was high in all regions (mean 89%), but lower for the MVC and AVC waves with significant variability between regions (mean 44% and 46%, respectively; p&amp;lt;0.001). Feasibility declined from basal to apical segments for all waves (p=0.0001). Mean mechanical wave velocity was slowest for the AK wave at 2.5 (2.0-3.0) m/s, faster for the AVC wave at 5.1 (3.5-6.3) m/s and fastest for the MVC wave at 6.6 (4.9-8.6) m/s (p=0.0001). Basal AK wave velocity was faster in patients with basal wall motion abnormalities compared to those without (2.7 vs. 2.0 m/s, p=0.0004) and could detect the presence of wall motion abnormalities adjusting for age, gender and parameters of diastolic function (univariable OR 3.4, 95% CI 1.5-7.7, p&amp;lt;0.01; multivariable OR 4.4, 95% CI 1.4-14.1, p=0.01). Basal AK wave velocity detected wall motion abnormalities with an AUC of 0.78 with cut-off speeds of 2.3 m/s and 3.0 m/s, both correctly classifying 73% of cases (sensitivity/specificity 81%/68% and 43%/89%, respectively). Mechanical wave velocities of other waves and in other regions were not consistently and only weakly associated with echocardiographic parameters of systolic and diastolic function. Conclusion(s) Mechanical wave velocities by CFWI detects myocardial dysfunction in acute coronary syndrome. Elevated basal AK wave velocity was independently associated with myocardial dysfunction where AK wave velocity ≥2.3 m/s provided a good sensitivity and ≥3.0 m/s a good specificity for detecting regional wall motion abnormalities. The feasibility of measuring the AK wave was good, whereas MVC and AVC waves had lower feasibility and were inadequate for assessment of myocardial function. Feasibility variations between AK and MVC/AVC waves suggest differences in wave propagation dynamics or intrinsic wave properties.Illustration Clutter Filter Wave ImagingRisk of myocardial dysfunction

Variation of Seismocardiogram-Derived Cardiac Time Intervals and Heart Rate Variability Metrics Across the Sternum

Abstract Cardiac time intervals (CTIs) are vital indicators of cardiac health and can be noninvasively assessed using a combination of electrocardiography (ECG) and seismocardiography (SCG), a method of capturing cardiac-induced chest vibrations via accelerometers. SCG signals can be measured from different chest locations. However, more investigations are needed to evaluate the impact of sensor placement on SCG-derived cardiac parameters. This study investigates the effect of accelerometer placement along the sternum on SCG-derived CTI estimations and heart rate variability (HRV) parameters. A semi-automated algorithm was developed to detect SCG fiducial points and seven CTIs from thirteen healthy individuals. Comparative analysis with manually selected peaks and gold-standard ECG was conducted to assess fiducial point detection accuracy. Results indicate the highest recall and precision in aortic valve opening (0.84–1.00 and 0.96–1.00, respectively) and mitral valve closure (0.77–1.00 and 0.93–1.00, respectively) detection. Aortic valve closure (0.43–1.00 and 0.61–1.00, respectively) and mitral valve opening (0.64–1.00 and 0.91–1.00, respectively) detection, although slightly less accurate due to signal intensity variations, demonstrated overall effectiveness compared to manually selected peaks. Furthermore, SCG-derived heart rates showed a high correlation coefficient (r &amp;gt; 0.9) with the gold-standard ECG heart rates. Single-factor ANOVA revealed significant differences (p &amp;lt; 0.05) in SCG-derived CTI estimations based on sensor locations on the sternum, highlighting the importance of sensor placement for accurate assessments.

Abstract Mo105: End Systolic Pressure and Ejection Timing Correlate with Impaired Relaxation

Impaired relaxation is a common feature in most cases of diastolic dysfunction, including heart failure with preserved ejection fraction. Isovolumetric relaxation is typically characterized by τ, an exponential time constant, but may be broken into relaxation and stiffness-like parameters (µ and Ek). Recent in vitro work suggests that strain during late systole (protodiastolic period) modifies relaxation. We hypothesize that late systolic pressure and time indexes correlate with myocardial relaxation. Thirty-four (34) simultaneous aortic and left ventricular micromanometric (Millar) pressure traces were obtained from a comprehensive database of clinical cardiac catheterization patients. These patients underwent coronary artery disease screening and presented but did not have arterial blockages. Pressure and time parameters were calculated over a five-minute interval. Relaxation rate (1/τ), and stiffness (Ek) correlated to end systolic parameters in an orthogonal pattern to relaxation (µ). 1/τ showed strong correlations with time from peak pressure to aortic valve divided by ejection time (t54/t52, r = .675, p &lt; .01) and moderate correlation to the pressure decline after peak pressure to aortic valve pressure divided by the pulse pressure (P45/P42, r = .577, p &lt; .01). In parallel Ek showed moderate correlation with t54/t52 (r = .592, p &lt; .01), and a moderate correlation with P45/P42 (r = .470, p &lt; .01), the pressure at aortic valve closure (r = -.420, p &lt; .05), and aortic augmentation index (AIx, r = -.360, p &lt; .05). Finally, µ presented a moderate correlation to P45/P42 (r = .501, p &lt; .05), the pressure at aortic valve closure (r = .404, p &lt; .05), and AIx (r = -.357, p &lt; .05). As predicted, ventricular relaxation in patients correlates with late systolic hemodynamics. Parameters or combinations of parameters may predict relaxation rates or correlate to in vivo late systolic strain. Prospective studies evaluating end systolic strain and relaxation merit consideration. Overall, these observations are consistent with in vitro studies that suggest that impaired cessation of contraction is a regulator of relaxation.

Temporal variability of electromechanical-window negativity in patients with inherited long-QT syndrome or drug-induced QT prolongation: relation to torsades de pointes

Abstract Background Electromechanical window (EMW) negativity is a novel parameter that identifies long-QT syndrome (LQTS) patients at increased arrhythmia risk. Whether the EMW remains stable or alters, especially close to arrhythmic events, is unknown. Purpose To study temporal variability of the EMW in controls and in patients with LQTS or drug-induced QT prolongation (di-QTprol), in relation to the timing of torsades de pointes (TdP) or ventricular fibrillation (VF). Methods In a retrospective cohort study with 5 participating centers, we assessed the EMW (ms) at 2 or 3 timepoints (if applicable, one of them close to TdP/VF) from cw-Doppler echocardiography in the apical long-axis view and concomitant ECG. EMW was calculated by subtracting the QT time from the aortic-valve closure time measured from QRS onset (surrogate of mechanical systole). Data are shown as mean±SD or median (25th to 75th percentile). Results Forty patients (75% female, 43±18 years old) were included: 8 controls, 27 LQTS (10 symptomatic: 9 TdP, 1 VF), and 5 di-QTprol (all TdP). LQTS genotypes were LQT1 (n=11), LQT2 (n=6), LQT3 (n=7), LQT7 (n=2), and genotype-negative (n=1). Overall, 67% of LQTS patients and 20% of di-QTprol were treated with β-blockers. Baseline QTc was 409±32 ms in controls, 444±32 ms in asymptomatic LQTS, 491±41 ms in symptomatic LQTS, and 498±49 ms in di-QTprol. Baseline EMW was 6±14 ms in controls, -12±29 ms in asymptomatic LQTS, -52±16 ms in symptomatic LQTS, and -5±69 ms in di-QTprol. Over years of follow-up, EMW remained stable in controls (8±10 ms; Fig. 1A) and the asymptomatic LQTS group (-17±20 ms; Fig. 1B). In LQTS patients with TdP/VF, EMW (baseline measured at -534 (-962 to -143) days before arrhythmia) had become profoundly more negative, -127±42 ms, (p=0.01 vs. baseline) at 1 (0 to 5) days after the arrhythmia and returned to basal values, -52±18 ms, (p=0.005) after 722 (155 to 3100) days (Fig. 1C). There was a significant correlation between time-to-event and EMW negativity (r=0.72, p&amp;lt;0.0001), indicating stronger EMW negativity when measured closer to TdP/VF. For the di-QTprol patients (n=2 amiodarone; n=2 escitalopram; n=1 sotalol) a trend towards more exaggerated EMW negativity was observed: from baseline (at -19 (-785 to -13) days before the event) to -125±33 ms (p=0.08 vs. baseline) at 1 (1 to 5) days after TdP (Fig. 1D). Again, significant correlation was found between time-to-event and EMW negativity (r=0.6, p=0.03). Conclusion Episodes of electrical instability in patients with LQTS or di-QTprol are associated with profound but reversible exaggeration of EMW negativity. If also present just prior to TdP/VF (as in experimental models of torsadogenic di-QTprol and anecdotal LQTS cases), imminent ventricular arrhythmias may be anticipated as electromechanical reciprocity may contribute to arrhythmogenesis.Figure 1Graphical Abstract

10 Pre-clinical studies of sotagliflozin in hypertrophic cardiomyopathy

OBJECTIVES/GOALS: Study the regulatory role of sodium glucose co-transporter 1 (SGLT1) in cardiomyocytes and the therapeutic potential of sotagliflozin in hypertrophic cardiomyopathy (HCM) by (a) quantifying SGLT1 expression in HCM and (b) examining the impact of sotagliflozin on cardiac mechanics. METHODS/STUDY POPULATION: * Use Western Blot in cardiac tissue from HCM and non-HCM patients and pre-existing RNA seq and proteomics datasets to quantify SGLT1 levels in HCM. Hypothesis: SGLT1 is upregulated in HCM * Determine how SGLT1/2 inhibition by sotagliflozin will affect cardiac mechanics using living myocardial slice (LMS) preparations. A vibratome creates 200um-thick slices from (a) failing HCM heart explants, (b) septal myectomy samples from HCM patients, and (c) nonfailing rejected donor hearts. LMS are mounted on a force transducer and work-loops are stimulated under varying pre- and after-loads. Collecting baseline and post-drug work loops allows each slice to function as its own control. Hypothesis: sotagliflozin will improve diastolic mechanics by reducing stiffness in the end-diastolic pressure-volume relationship RESULTS/ANTICIPATED RESULTS: * Preliminary results from RNA seq data indicate that SLC5A1 mRNA (encoding gene for SGLT1) is significantly decreased in HCM. No proteomics study examined thus far has detected SLC5A1, indicating that overall SGLT1 levels in cardiac tissue are quite low. We will examine SGLT1 levels in our own HCM and non-HCM tissue samples with both mass-spectrometry and Western Blot. * We analyze six slices from each heart and expect 15 donor hearts and 15 HCM hearts/myectomy samples. We visualize the work loop by plotting stress/strain. Stress/strain at mitral valve closure represents exponential end diastolic pressure-volume relationship; Stress/strain at aortic valve closure represents linear end systolic pressure volume relationship. A two-sample paired t-test will compare change in stiffness and elastance. DISCUSSION/SIGNIFICANCE: This project contributes to a growing body of research surrounding the currently unknown cardioprotective mechanism of SGLT 1/2 inhibitors, furthers the technique of using living myocardial slices to study cardiac mechanics, and supports a trial examining sotagliflozin in HCM, for which disease modifying therapy remains a prevailing unmet need.

Is the Corrected Carotid Flow Time a Clinically Acceptable Surrogate Hemodynamic Parameter for the Left Ventricular Ejection Time?

ObjectiveThe corrected left ventricular ejection time (cLVET) comprises the phase from aortic valve opening to aortic valve closure corrected for heart rate. As a surrogate measure for cLVET, the corrected carotid flow time (ccFT) has been proposed in previous research. The aim of this study was to assess the clinical agreement between cLVET and ccFT in a dynamic clinical setting. MethodsTwenty-five patients with severe aortic valve stenosis (AS) were selected for transcatheter aortic valve replacement (TAVR). The cLVET and ccFT were derived from the left ventricular outflow tract (LVOT) and the common carotid artery (CCA) respectively, using pulsed wave Doppler ultrasound. Bazett's (B) and Wodey's (W) equation were used to calculate cLVET and ccFT. Measurements were performed directly before (T1), and after (T2) TAVR. Correlation, Bland-Altman, and concordance analyses were performed. ResultsThe cLVET decreased from T1 to T2 (p<0.001), with a relative reduction of 11% (B) and 9% (W). The ccFT decreased (p<0.001) with a relative reduction of 12% (B) and 10% (W). The correlation between cLVET and ccFT was strong for B (ρ=0.74, p<0.001), and W (ρ=0.81, p<0.001). The bias was -39 ms (B) and -37 ms (W), and the upper and lower level of agreement were 19 ms and -98 ms (B) and 5 ms and -78 ms (W), respectively. The trending ability between cLVET and ccFT was good (concordance 96%) for both B and W. ConclusionIn TAVR patients, the clinical agreement between cLVET and ccFT was acceptable, indicating that ccFT could serve as a surrogate measure for cLVET.

A Study of the Usefulness of Tissue Doppler Imaging for the Diagnosis of Coronary Artery Disease in Patients with Left Bundle Branch Block

Abstract Background: In patients with left bundle branch block (LBBB), the diagnosis of ischemia by noninvasive modalities is cumbersome. Most of them such as stress tests, nuclear imaging, and magnetic resonance imaging have limitations in the detection of ischemia in this subset. The postsystolic motion (PSM) during the isovolumetric relaxation period on tissue Doppler imaging (TDI) is a sensitive and specific marker of ischemia. We aimed to see whether the TDI parameters can detect coronary artery disease (CAD) in patients with LBBB. Materials and Methods: Patients with LBBB (n = 64) who underwent coronary angiography were divided into two groups. Group A (n = 30) included patients with left anterior descending (LAD) artery stenosis of ≥70%, and group B (n = 34) included patients without LAD stenosis. All patients underwent TDI and various myocardial tissue velocity parameters were analyzed to detect the presence of CAD. P &lt; 0.05 was considered significant. Results: The TDI of the mid-interventricular septum showed a higher delayed amplitude of PSM (&gt;100 ms after aortic valve closure), lower myocardial systolic (Sm), and early diastolic (Em) velocities, and a higher late diastolic (Am) velocity in group A when compared to group B (all were significant, P &lt; 0.0001). Both the ratios Sm/PSM and Em/Am were significantly lower in group A compared to group B (P &lt; 0.0001). On receiver operating characteristic curve analysis to predict the presence of significant LAD stenosis, the value of Sm/PSM ratio &lt;0.8 showed the best combination of sensitivity (78%) and specificity (96%) with an area under the curve of 0.936. Conclusion: TDI, a noninvasive imaging modality, is reliable and effective in identifying myocardial ischemia in patients with LBBB.

Mechanocardiography detects improvement of systolic function caused by resynchronization pacing.

Objective.Cardiac resynchronization therapy (CRT) is commonly used to manage heart failure with dyssynchronous ventricular contraction. CRT pacing resynchronizes the ventricular contraction, while AAI (single-chamber atrial) pacing does not affect the dyssynchronous function. This study compared waveform characteristics during CRT and AAI pacing at similar pacing rates using seismocardiogram (SCG) and gyrocardiogram (GCG), collectively known as mechanocardiogram (MCG).Approach.We included 10 patients with heart failure with reduced ejection fraction and previously implanted CRT pacemakers. ECG and MCG recordings were taken during AAI and CRT pacing at a heart rate of 80 bpm. Waveform characteristics, including energy, vertical range (amplitude) during systole and early diastole, electromechanical systole (QS2) and left ventricular ejection time (LVET), were derived by considering 6 MCG axes and 3 MCG vectors across frequency ranges of >1 Hz, 20-90 Hz, 6-90 Hz and 1-20 Hz.Main results.Significant differences were observed between CRT and AAI pacing. CRT pacing consistently exhibited higher energy and vertical range during systole compared to AAI pacing (p< 0.05). However, QS2, LVET and waveform characteristics around aortic valve closure did not differ between the pacing modes. Optimal differences were observed in SCG-Y, GCG-X, and GCG-Y axes within the frequency range of 6-90 Hz.Significance.The results demonstrate significant differences in MCG waveforms, reflecting improved mechanical cardiac function during CRT. This information has potential implications for predicting the clinical response to CRT. Further research is needed to explore the differences in signal characteristics between responders and non-responders to CRT.

Abstract 16969: Assessment of the Electromechanical Window in Patients With Conventional Biventricular Pacing as Compared to Patients With Conduction System Pacing

Introduction: The Electromechanical Window (EMW) is a validated measurement reflecting electromechanical coupling of the ventricles, and is defined as the difference between electrical and mechanical ventricular activation times. A larger (more negative) EMW is associated with worse clinical outcomes, especially greater arrhythmic risk, in various clinical conditions such as long QT syndrome, risk of drug-inducd torsade, hypertrophic cardiomyopathy, etc. Cardiac resynchronization therapy (CRT) can be achieved by conventional bi-ventricular pacing (BiVP) or conduction system pacing (CSP). We assessed the EMW in patients undergoing CRT via these 2 modalities. Methods: Total mechanical activation time was measured from the 5 chamber echocardiographic view as the interval (ms) from the onset of the Q wave to aortic valve closure (mean of 3 measurements). Total electrical activation time (QTcBazett interval, ms) was measured from 12 lead ECGs recorded within 24 hours of the echocardiogram. The EMW was calculated as the difference between the QTc and the mechanical ventricular activation time. Results: A total of 60 pts (BiVP=31, CSP=29) were analyzed. There was no significant difference between the heart rates during the ECG and the echocardiogram recorded within 24 hours of each other (74.6 ± 16.5 vs 71.5 ± 12.0 bpm, P=NS). The EMW was significantly more negative in patients with BiVP as compared to CSP (-99.5 ± 70.9 vs -55.2 ± 52.7 ms, P=0.03). When restricting the analysis to patients where the ECG and echocardiographic HRs were within 10 bpm of each other, the difference remained significant (P=0.03). Conclusions: Patients in whom CRT is achieved by CSP have less negative EMWs as compared to patients with BiVP. Based on the known association of more negative EMW with increased arrhythmic risk, these data, if confirmed in larger populations with correlation to clinical outcomes, add to the growing evidence to support CSP as the preferred modality for achieving CRT.

Abstract 17322: Closing the Loop: Use of Amplatzer PFO Occluder Device in Case of LVAD-Associated Aortic Insufficiency

Description of Case: A 72-year-old woman with destination therapy Heartmate 3 left ventricular assist device (LVAD) presented with NYHA Class III symptoms. Review of her echocardiograms since LVAD implantation revealed progressive central aortic insufficiency (AI) with subsequent LV dilatation, managed with reduction in LVAD speed. Patient declined surgical aortic valve replacement and/or repair. After a multidisciplinary discussion, the patient opted to pursue percutaneous aortic valve closure. Cardiac CT demonstrated no aortic valve thrombus and identified appropriate anatomy for closure with an 18x25 mm Amplatzer PFO Occluder device (Graphic 1). Preoperative TEE revealed LV ejection fraction of 15% with moderate to severe AI and fibrosis of the aortic valve commissures with no aortic valve movement. The aortic valve was closed with the Amplatzer PFO Occluder with an 18mm disk that sat on the LV side of the aortic valve within the AV annulus and the 25mm disk sitting on the aortic side of the aortic valve within the sinus of Valsalva. TEE and intracardiac echocardiography demonstrated excellent device placement with two residual trace AI jets at the non-left and left-right commissure. Following LVAD speed increase, the degree of AI remained unchanged and she was discharged with improved symptoms. Discussion: Moderate-severe AI develops in about 15-25% of patients within 1 year of LVAD implantation. There are previous reports of LVAD-associated AI closure with an Amplatzer cribiform device. We describe the first known use of the Amplatzer PFO Occluder device for the management of LVAD-associated AI. While transcatheter aortic valve replacement (TAVR) is an attractive option to treat LVAD-associated AI, securing the transcatheter heart valve in the absence of calcifications remains a challenge.

Electromechanical Window and Spontaneous Ventricular Tachyarrhythmias in Takotsubo Syndrome

QT interval prolongation is common in patients hospitalized with Takotsubo syndrome (TTS), however, only a minority experience ventricular tachyarrhythmias. Our aim was to characterize the electromechanical window (EMW) in patients with TTS and to evaluate its association with ventricular tachyarrhythmias. We preformed aretrospective analysis of 84 patients hospitalized with TTS in the Tel-Aviv Medical Center between 2013 and 2022. All patients underwent a comprehensive echocardiographic evaluation and the EMW was calculated by subtracting the QT interval from the QRS onset to the aortic valve closure obtained from a continuous-wave Doppler for the same beat. Of the 84 patients with TTS, 74 (88%) were female and the mean age was 70 ± 11 years. The mean left ventricular ejection fraction was 42 ± 8%. The EMW was negative in 81 patients (96%), and the mean EMW was -69 ± 50 ms. Ventricular tachyarrhythmias occurred in 7 patients (8%). The EMW of patients who experienced ventricular tachyarrhythmias was more negative than patients who did not (-133 ± 23 ms vs -63 ± 48 ms, p = 0.001). In the univariate analysis, EMW and QT were associated with ventricular tachyarrhythmias (univariate odds ratio [OR]EMW1.03, 95% confidence interval [CI] 1.01 to 1.05, p = 0.003 and univariate ORQTc1.02, 95% CI 1.01 to 1.03, p = 0.02); however, only EMW remained significant in the multivariate analysis (OREMW1.03 95% CI 1.03 to 1.05, p = 0.023). EMW was more effective than corrected QT interval in identifying patients who had ventricular tachyarrhythmias (AUCEMW: 0.89, 95% CI 0.82 to 0.97 vs AUCQTc0.77, 95% CI 0.61 to 0.93, p = 0.02), and a cut-off value of -108 ms was predictive of ventricular tachyarrhythmias with a sensitivity of 86% and a specificity of 79%. In conclusion, EMW is negative in patients with TTS and is associated with increased risk for ventricular tachyarrhythmias. The role of EMW in the risk stratification of patients with TTS warrants further investigation.

Exploring the Impact of Sensor Location on Seismocardiography-Derived Cardiac Time Intervals

Abstract Cardiac time intervals (CTIs) are important parameters for evaluating cardiac function and can be measured noninvasively through electrocardiography (ECG) and seismocardiography (SCG). SCG signals exhibit distinct spectrotemporal characteristics when acquired from various locations on the chest. Thus, this study aimed to explore how SCG measurement location affects the estimation of SCG-based CTIs. ECG and SCG signals were acquired from 14 healthy adults, with three accelerometers placed on the top, middle, and bottom of the sternum. A custom-built algorithm was developed to estimate heart rates (HRs) from ECG (HRECG) and SCG (HRSCG) signals. Moreover, SCG fiducial points and CTIs, including aortic valve opening and closure, R-R interval, pre-ejection period, left ventricular ejection time, and electromechanical systole, were estimated from the SCG signals at different sternal locations. The average and correlation coefficient (R2) of the CTIs and HRs derived from all three locations were compared, along with the analysis of mean differences for the CTIs and their corresponding sensor locations. The results indicated strong correlations between HRECG and HRSCG, with average R2 values of 0.9930, 0.9968, and 0.9790 for the top, middle, and bottom sternal locations, respectively. Additionally, the study demonstrated that SCG-based CTIs varied depending on the SCG measurement locations. In conclusion, these findings underscore the importance of establishing consistent protocols for reporting CTIs based on SCG. Furthermore, they call for further investigation to compare estimated CTIs with gold-standard methods like echocardiography to identify the best SCG measurement location for accurate CTI estimations.

Mechanical Wave Velocities in Left Ventricular Walls in Healthy Subjects and Patients With Aortic Stenosis

BackgroundMechanical wave velocity (MWV) measurement is a promising method for evaluating myocardial stiffness, because these velocities are higher in patients with myocardial disease. ObjectivesUsing high frame rate echocardiography and a novel method for detection of myocardial mechanical waves, this study aimed to estimate the MWVs for different left ventricular walls and events in healthy subjects and patients with aortic stenosis (AS). Feasibility and reproducibility were evaluated. MethodsThis study included 63 healthy subjects and 13 patients with severe AS. All participants underwent echocardiographic examination including 2-dimensional high frame rate recordings using a clinical scanner. Cardiac magnetic resonance was performed in 42 subjects. The authors estimated the MWVs at atrial kick and aortic valve closure in different left ventricular walls using the clutter filter wave imaging method. ResultsMechanical wave imaging in healthy subjects demonstrated the highest feasibility for the atrial kick wave reaching >93% for all 4 examined left ventricular walls. The MWVs were higher for the inferolateral and anterolateral walls (2.2 and 2.6 m/s) compared with inferoseptal and anteroseptal walls (1.3 and 1.6 m/s) (P < 0.05) among healthy subjects. The septal MWVs at aortic valve closure were significantly higher for patients with severe AS than for healthy subjects. ConclusionsMWV estimation during atrial kick is feasible and demonstrates higher velocities in the lateral walls, compared with septal walls. The authors propose indicators for quality assessment of the mechanical wave slope as an aid for achieving consistent measurements. The discrimination between healthy subjects and patients with AS was best for the aortic valve closure mechanical waves. (Ultrasonic Markers for Myocardial Fibrosis and Prognosis in Aortic Stenosis; NCT03422770)

Left ventricular decompression in veno-arterial extracorporeal membrane oxygenation

Objective: Our study investigates the frequency and determines the characteristics and outcomes of patients with venoarterial extracorporeal membrane oxygenation (VA-ECMO) support requiring left ventricular unloading at Ha Noi Heart hospital.&#x0D; Methods: A cross-sectional descriptive study was conducted among 84 patients undergoing VA- ECMO between December 2018 and December 2021 at Ha Noi Heart hospital. Signs of left ventricular distension in VA-ECMO (Inadequate arterial blood pressure pulsatility, “smoke like” effect in left ventricular, reduced aortic valve opening/absent aortic valve closure, pulmonary edema, left ventricular distension) were studied before and at 24 hours, 48 hours and 72 hours after VA-ECMO support.&#x0D; Results: Left ventricular distention requiring decompression occurs in 44,1% of patients supported with VA-ECMO 3.6% (left ventricular distension), inadequate arterial blood pressure pulsatility (77,4%), “smoke like” effect in left ventricular (53,6%), pulmonary edema 47 ,6%; reduced aortic valve opening/absent aortic valve closure in 35,7% of the cases. Left ventricular decompression may improve clinical outcomes from 48 hours onwards (p&lt;0.05). There were no differences in age, left ventricular ejection fraction before VA-ECMO, ECRP rates, continuous renal replacement therapy rates, duration of mechanical ventilation, duration of ECMO, hospital length of stay and diagnosis of patients with and without left ventricular unloading (p&gt;0.05). The proportion of patients using invasive left ventricular decompression who successful weaning from VA- ECMO was significantly higher than in the group without left ventricular unloading (94,5% versus 74,4%; p&lt;0.05).The survival rate of patients using left ventricular unloading tended to be higher than that in the group without left ventricular decompression (72,9% vs 53,2%; p&gt;0.05) ). Complications of invasive left ventricular decompression included 1 patient with occlusion of the junction requires removal of the left atrial drainage.&#x0D; Conclusion: Left heart decompression may contribute to increasing the success rate of VA-ECMO weaning and may help to improve the survival rate of patients with VA ECMO.

Hemodynamic effects of a dielectric elastomer augmented aorta on aortic wave intensity: An in-vivo study

Dielectric elastomer actuator augmented aorta (DEA) represents a novel approach with high potential for assisting a failing heart. The soft tubular device replaces a section of the aorta and increases its diameter when activated. The hemodynamic interaction between the DEA and the left ventricle (LV) has not been investigated with wave intensity (WI) analysis before. The objective of this study is to investigate the hemodynamic effects of the DEA on the aortic WI pattern. WI was calculated from aortic pressure and flow measured in-vivo in the descending aorta of two pigs implanted with DEAs. The DEAs were tested for different actuation phase shifts (PS). The DEA generated two decompression waves (traveling upstream and downstream of the device) at activation followed by two compression waves at deactivation. Depending on the PS, the end-diastolic pressure (EDP) decreased by 7% (or increased by 5–6%). The average early diastolic pressure augmentation (Pdia¯) increased by 2% (or decreased by 2–3%). The hydraulic work (WH) measured in the aorta decreased by 2% (or increased by 5%). The DEA-generated waves interfered with the LV-generated waves, and the timing of the waves affected the hemodynamic effect of the device. For the best actuation timing the upstream decompression wave arrived just before aortic valve opening and the upstream compression wave arrived just before aortic valve closure leading to a decreased EDP, an increased Pdia¯ and a reduced.WH.

Evaluation of Myocardial Stiffness in Cardiac Amyloidosis Using Acoustic Radiation Force Impulse and Natural Shear Wave Imaging.

Increased myocardial stiffness (MS) is an important hallmark of cardiac amyloidosis (CA) caused by myocardial amyloid deposition. Standard echocardiography metrics assess MS indirectly via downstream effects of cardiac stiffening. The ultrasound elastography methods acoustic radiation force impulse (ARFI) and natural shear wave (NSW) imaging assess MS more directly. This study compared MS in 12 healthy volunteers and 13 patients with confirmed CA using ARFI and NSW imaging. Parasternal long-axis acquisitions of the interventricular septum were obtained using a modified Acuson Sequoia scanner and a 5V1 transducer. ARFI-induced displacements were measured through the cardiac cycle, and ratios of diastolic-over-systolic displacement were calculated. NSW speeds from aortic valve closure were extracted from echocardiography-tracked displacement data. ARFI stiffness ratios were significantly lower in CA patients than controls (mean ± standard deviation: 1.47 ± 0.27 vs. 2.10 ± 0.47, p < 0.001), and NSW speeds were significantly higher in CA patients than controls (5.58 ± 1.10 m/s vs. 3.79 ± 1.10 m/s, p < 0.001). A linear combination of the two metrics exhibited greater diagnostic potential than either metric alone (area under the curve=0.97 vs. 0.89 and 0.88). MS was measured to be significantly higher in CA patients using both ARFI and NSW imaging. Together, these methods have potential utility to aid in clinical diagnosis of diastolic dysfunction and infiltrative cardiomyopathies.

Preoperative higher right ventricular stroke work index increases the risk of de novo aortic insufficiency after continuous-flow left ventricular assist device implantation

During continuous-flow left ventricular assist device (CF-LVAD) support, hemodynamic shear stress causes a burden on aortic valve (AV) leaflets, leading to de novo aortic insufficiency (AI). This study investigated the influence of preoperative hemodynamic parameters on de novo AI in CF-LVAD recipients. We reviewed 125 patients who underwent CF-LVAD implantation without concomitant AV surgery between 2005 and 2018. De novo AI was defined as moderate or severe AI in those with none or trivial preoperative AI. During mean 30 ± 16 months of CF-LVAD support, de novo AI-free rate was 86% and 67% at 1 and 2 years, respectively. Multivariable analysis showed that higher right ventricular stroke work index (RVSWI) (hazard ratio, 1.12 /g/m2/beat; 95% confidence interval, 1.00–1.20; p = 0.047) and trivial grade AI (hazard ratio, 2.8; 95% confidence interval, 1.2–6.4; p = 0.020) were independent preoperative risk factors for de novo AI. The longitudinal analysis using generalized mixed effects model showed that higher RVSWI was associated with continuous AV closure after LVAD implantation (Odd ratio, 1.20/g/m2/beat; 95% confidence interval, 1.00–1.43 /g/m2/beat; p = 0.047). Right heart catheterization revealed that preoperative RVSWI was positively correlated with postoperative pump flow index in patients with continuously closed AV (r = 0.44, p = 0.04, n = 22). Preoperative higher RVSWI was a significant risk factor for de novo AI following CF-LVAD implantation. In patients with preserved right ventricular function, postoperative higher pump flow may affect AI development via hemodynamic stress on the AV.