Atrioventricular Plane Research Articles

Left Ventricular Diastolic Function in Children with Atrial Septal Defects Improves After Closure by Means of Increased Hydraulic Force

AbstractHydraulic force aids diastolic filling of the left ventricle (LV) by facilitating basal movement of the atrioventricular plane. The short-axis atrioventricular area difference (AVAD) determines direction and magnitude of this force. Patients with atrial septal defect (ASD) have reduced LV filling due to the left-to-right shunt across the atrial septum and thus potentially altered hydraulic force. The aims were therefore to use cardiac magnetic resonance images to assess whether AVAD and thus the hydraulic force differ in children with ASD compared to healthy children, and if it improves after ASD closure. Twenty-two children with ASD underwent cardiac magnetic resonance before ASD closure. Of these 22 children, 17 of them repeated their examination also after ASD closure. Twelve controls were included. Left atrial and ventricular areas were delineated in short-axis images, and AVAD was defined as the largest ventricular area minus the largest atrial area at each time frame and normalized to body height (AVADi). At end diastole AVADi was positive in all participants, suggesting a force acting towards the atrium assisting the diastolic movement of the atrioventricular plane; however, lower in children both before (6.3 cm2/m [5.2–8.0]; p < 0.0001) and after ASD closure (8.7 cm2/m [6.6–8.5]; p = 0.0003) compared to controls (12.2 cm2/m [11.3–13.9]). Left ventricular diastolic function improves after ASD closure in children by means of improved hydraulic force assessed by AVAD. Although AVADi improved after ASD closure, it was still lower than in controls, indicating diastolic abnormality even after ASD closure. In patients where AVADi is low, ASD closure may help avoid diastolic function deterioration and improve outcome. This could likely be important also in patients with small shunt volumes, especially if they are younger, who currently do not undergo ASD closure. Changes in clinical routine may be considered pending larger outcome studies.

Whole-heart modelling with valves in a fluid–structure interaction framework

Computational modelling of whole-heart function is a useful tool to study heart mechanics and haemodynamics. Many existing heart models focus on electromechanical aspect without considering physiological valves and use simplified fluid models instead. In this study we develop a four-chamber heart model featuring realistic chamber geometry, detailed valve modelling, hyperelasticity with fibre architecture and fluid–structure interaction analysis. Our model is used to investigate heart behaviours with different modelling assumptions including restricted/free valve annular dynamics, and with/without heart-pericardium interactions. Our simulation results capture the interactions between valve leaflet and surrounding flow, typical left ventricular flow vortices, typical venous and transvalvular flow waveform, and physiological heart deformations such as atrioventricular plane movement. The improvement of ventricular filling and atrial emptying at early diastole is evident with free annulus. In addition, we find that the added pericardial forces on the heart have a predominant effect on atrial wall deformation especially during atrial contraction, and further help with the atrial filling process. Most importantly, the current study provides a framework for comprehensive multi-physics whole-heart modelling considering all heart valves and fluid–structure interactions.

Deep learning from atrioventricular plane displacement in patients with Takotsubo syndrome: lighting up the black-box.

The spatiotemporal deep convolutional neural network (DCNN) helps reduce echocardiographic readers' erroneous 'judgement calls' on Takotsubo syndrome (TTS). The aim of this study was to improve the interpretability of the spatiotemporal DCNN to discover latent imaging features associated with causative TTS pathophysiology. We applied gradient-weighted class activation mapping analysis to visualize an established spatiotemporal DCNN based on the echocardiographic videos to differentiate TTS (150 patients) from anterior wall ST-segment elevation myocardial infarction (STEMI, 150 patients). Forty-eight human expert readers interpreted the same echocardiographic videos and prioritized the regions of interest on myocardium for the differentiation. Based on visualization results, we completed optical flow measurement, myocardial strain, and Doppler/tissue Doppler echocardiography studies to investigate regional myocardial temporal dynamics and diastology. While human readers' visualization predominantly focused on the apex of the heart in TTS patients, the DCNN temporal arm's saliency visualization was attentive on the base of the heart, particularly at the atrioventricular (AV) plane. Compared with STEMI patients, TTS patients consistently showed weaker peak longitudinal displacement (in pixels) in the basal inferoseptal (systolic: 2.15 ± 1.41 vs. 3.10 ± 1.66, P < 0.001; diastolic: 2.36 ± 1.71 vs. 2.97 ± 1.69, P = 0.004) and basal anterolateral (systolic: 2.70 ± 1.96 vs. 3.44 ± 2.13, P = 0.003; diastolic: 2.73 ± 1.70 vs. 3.45 ± 2.20, P = 0.002) segments, and worse longitudinal myocardial strain in the basal inferoseptal (-8.5 ± 3.8% vs. -9.9 ± 4.1%, P = 0.013) and basal anterolateral (-8.6 ± 4.2% vs. -10.4 ± 4.1%, P = 0.006) segments. Meanwhile, TTS patients showed worse diastolic mechanics than STEMI patients (E'/septal: 5.1 ± 1.2 cm/s vs. 6.3 ± 1.5 cm/s, P < 0.001; S'/septal: 5.8 ± 1.3 cm/s vs. 6.8 ± 1.4 cm/s, P < 0.001; E'/lateral: 6.0 ± 1.4 cm/s vs. 7.9 ± 1.6 cm/s, P < 0.001; S'/lateral: 6.3 ± 1.4 cm/s vs. 7.3 ± 1.5 cm/s, P < 0.001; E/E': 15.5 ± 5.6 vs. 12.5 ± 3.5, P < 0.001). The spatiotemporal DCNN saliency visualization helps identify the pattern of myocardial temporal dynamics and navigates the quantification of regional myocardial mechanics. Reduced AV plane displacement in TTS patients likely correlates with impaired diastolic mechanics.

Abstract 16610: A New Left Ventricle Vortex Formation Time for Clinical Assessment of Diastolic Filling Efficiency Based on Direct Mechanical Ventricular-Vascular Coupling: Evaluation in Heart-Failure and Healthy Cohort

Introduction: The mechanical coupling of the left ventricle (LV) and aorta creates the apical motion of the atrioventricular plane (AVP), resembling a piston-cylinder system, impacting early diastolic filling (J Am Heart Assoc. 2017;6:e004903). Furthermore, several clinical studies have suggested the vortex formation time (VFT) as an indicator of LV diastolic function (Eur. Heart J. Cardiovasc. Imaging. 2012;13(5):385-93). However, conflicting results exist in previous clinical studies, potentially due to deviations from the original fluid dynamics definition of VFT in a piston-in-cylinder setting. In this study, we propose a new VFT approach to assess LV diastolic filling performance based on direct mechanical ventricular-vascular coupling. Methods: Cardiac MRI was used on 69 healthy individuals and 19 heart failure (HF) patients. The clinical cohort (37% women) had a mean age of 46 [± 17.5] years and BMI of 24.8 [±4.5]. LV valvular diseases were excluded. VFT was assessed using the original L/D definition, where L represents ascending aortic recoil motion (piston displacement) and D represents the mitral valve orifice. Aortic displacement was measured on the three and four-chamber MRI scans by tracing the AVP. Mitral valve orifice was determined as the average of commissure distance (short-axis images) and the leaflet tip distance (three-chamber view). Results: The new VFT approach yielded a mean[± std.] of 4.73[±0.89] for the healthy group, and considerably lower values (3.24±0.83) for the patients with HF (figure 1). Conclusions: The proposed VFT based on the mechanical ventricular-vascular coupling and original fluid dynamic formulation, demonstrates a theoretical optimal value of approximately 4 in healthy individuals, while significantly lower in HF. This novel VFT has the potential to address existing discrepancies regarding the clinical significance of VFT and establish it as a promising indicator of left ventricular filling efficiency.

Fully automated AI-based cardiac motion parameter extraction – application to mitral and tricuspid valves on long-axis cine MR images

PurposeIn cardiac MRI, valve motion parameters can be useful for the diagnosis of cardiac dysfunction. In this study, a fully automated AI-based valve tracking system was developed and evaluated on 2- or 4-chamber view cine series on a large cardiac MR dataset. Automatically derived motion parameters include atrioventricular plane displacement (AVPD), velocities (AVPV), mitral or tricuspid annular plane systolic excursion (MAPSE, TAPSE), or longitudinal shortening (LS). MethodTwo sequential neural networks with an intermediate processing step are applied to localize the target and track the landmarks throughout the cardiac cycle. Initially, a localisation network is used to perform heatmap regression of the target landmarks, such as mitral, tricuspid valve annulus as well as apex points. Then, a registration network is applied to track these landmarks using deformation fields. Based on these outputs, motion parameters were derived. ResultsThe accuracy of the system resulted in deviations of 1.44 ± 1.32 mm, 1.51 ± 1.46 cm/s, 2.21 ± 1.81 mm, 2.40 ± 1.97 mm, 2.50 ± 2.06 mm for AVPD, AVPV, MAPSE, TAPSE and LS, respectively. Application on a large patient database (N = 5289) revealed a mean MAPSE and LS of 9.5 ± 3.0 mm and 15.9 ± 3.9 % on 2-chamber and 4-chamber views, respectively. A mean TAPSE and LS of 13.4 ± 4.7 mm and 21.4 ± 6.9 % was measured. ConclusionThe results demonstrate the versatility of the proposed system for automatic extraction of various valve-related motion parameters.

Determinants of left atrial reservoir strain in a large healthy population

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Centre for Innovative Ultrasound Solutions Nord-Trøndelag Hospital Trust. Background Echocardiographic evaluation of the left atrium (LA) has until recently been done by assessment of LA end-systolic volume (LAESV) or Doppler measurements. While these measurements provide prognostic information, they indirectly measure LA function. LA reservoir strain, however, is a direct measurement of LA function and provides additional prognostic information but is affected by the left ventricle (LV) through movement of the atrioventricular plane. Purpose By evaluation of echocardiograms from a large healthy population we aimed to study the associations of LA reservoir strain with age, LA-, and LV volumes, and LV global longitudinal strain (LV GLS). Methods Echocardiographic acquisitions and analyses were performed according to current recommendations. All study personnel were experienced and affiliated with a European Association of Cardiovascular Imaging accredited echocardiographic laboratory. The associations of LA reservoir strain as outcome variable with age, LAESV, LV end-diastolic volume (LVEDV) and LV GLS were assessed by multiple linear regression analyses. Results In total 1412 subjects (56% females) with mean (SD) age 57 (12) years were included. Mean LVEF was 60.4% in females and 59.6% in males. Totally, 39% of the variance in LA reservoir strain between subjects was explained by age, LAESV, LVEDV and LV GLS (Table 1). All four characteristics were significantly associated with LA reservoir strain (all p&amp;lt;0.001). Age and LV GLS were the two most important characteristics for determining LA reservoir strain, indicating lower LA reservoir strain with higher age and lower absolute LV GLS. Six years of higher age had a similar effect as one percent lower absolute LV GLS. Similarly, 28 mL larger LAESV and 35mL smaller LVEDV corresponded to one percent lower absolute LV GLS. Conclusion In this large healthy population, almost 40% of the variance in LA reservoir strain between subjects was explained by age, LV GLS, and the volumes of LA and LV. The most important determinants were age and GLS, contributing equally to a reduction of LA reservoir strain with higher age and lower absolute LV GLS. Correspondingly, the size of LA and LV contributed less to the variability of LA reservoir strain. In conclusion, both age and LV function should be considered when interpreting LA reservoir strain.

Heart function by M-mode and tissue Doppler in the early neonatal period in neonates with fetal growth restriction

BackgroundFetal growth restricted (FGR) neonates have increased risk of circulatory compromise due to failure of normal transition of circulation after birth. AimEchocardiographic assessment of heart function in FGR neonates first three days after birth. Study designProspective observational study. SubjectsFGR- and non-FGR neonates. Outcome measuresM-mode excursions and pulsed-wave tissue Doppler velocities normalised for heart size and E/e′ of the atrioventricular plane day one, two and three after birth. ResultsCompared with controls (non-FGR of comparable gestational age, n = 41), late-FGR (gestational age ≥ 32 weeks, n = 21) exhibited higher septal excursion (15.9 (0.6) vs. 14.0 (0.4) %, p = 0.021) (mean (SEM)) and left E/e′ (17.3 (1.9) vs.11.5 (1.3), p = 0.019). Relative to day three, indexes on day one were higher for left excursion (21 (6) % higher on day one, p = 0.002), right excursion (12 (5) %, p = 0.025), left e′ (15 (7) %, p = 0.049), right a′ (18 (6) %, p = 0.001), left E/e′ (25 (10) %, p = 0.015) and right E/e′ (17 (7) %, p = 0.013), whereas no index changed from day two to day three. Late-FGR had no impact on changes from day one and two to day three. No measurements differed between early-FGR (n = 7) and late-FGR. ConclusionsFGR impacted neonatal heart function the early transitional days after birth. Late-FGR hearts had increased septal contraction and reduced left diastolic function compared with controls. The dynamic changes in heart function between first three days were most evident in lateral walls, with similar pattern in late-FGR and non-FGR. Early-FGR and late-FGR exhibited similar heart function.

The Incidence and Impact of Permanent Right Ventricular Infarction on Left Ventricular Infarct Size in Patients With Inferior ST-Segment Elevation Myocardial Infarction

Mounting evidence shows that right ventricle (RV) function carries independent prognostic influence in various disease states. This study aimed to investigate the incidence and impact of permanent RV infarction in patients with inferior ST-segment elevation myocardial infarction (STEMI) and culprit lesion in the right coronary artery (RCA). In this substudy of the DANAMI-3 (DANish Study of Optimal Acute Treatment of Patients with ST-segment Elevation Myocardial Infarction) trial, cardiac magnetic resonance was performed in 291 patients at day 1 and follow-up 3 months after primary percutaneous coronary intervention of 674 patients with STEMI with the culprit lesion in the RCA. Final infarct was assessed using late gadolinium enhancement on cardiac magnetic resonance at 3 months. Patients with permanent RV infarction (20%) had lower ventricular function at follow-up; RV ejection fraction (EF) 47% ±6 versus 50% ± 5 (p <0.005) and left ventricular (LV) EF 56% ± 8 versus 60% ± 9 (p <0.006). Furthermore, patients with permanent RV infarction had a higher incidence of microvascular obstruction 39 (67%) versus 81 (39%) (p <0.001), larger final LV infarct size 16% ±8 versus 10% ± 8 (p <0.001) and larger LV area at risk 33% ± 10 versus 29% ± 9 (p <0.001). Permanent RV infarction was an independent predictor of final LV infarct size (p <0.001) but was not associated with LVEF (β=-0.0; p=0.13) in multivariable analyses. In conclusion, permanent RV infarction was seen in 20% of patients with inferior STEMI and culprit lesion in RCA and independently predicted final LV infarct size. However, permanent RV infarction did not predict overall LV function. LGE was used to detect infarct location and quantify infarct size.17 LGE in RV free wall on follow-up CMR was considered as permanent infarction. LGE images were obtained 10 minutes after intravenous injection of 0.1-mmol/kg body weight of gadolinium-based contrast (Gadovist; Bayer Schering, Berlin, Germany) using an electrocardiogram (ECG)-triggered inversion-recovery sequence. The inversion time was adjusted to null the signal from the normal myocardium. Short-axis images were acquired from the atrioventricular plane to the apex with adjacent 8-mm slices. The remaining protocol has been described previously.16.

Fully automatic AI-based valve motion parameter extraction on long axis CINE images - application on N=11000 patient datasets

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Research support from Siemens Healthineers GmbH. Background Mitral valve (MV) motion parameters, assessable using CMR [1, 2], have been shown to help the diagnosis of cardiac dysfunction. To extract valve motion parameters, we propose a fully automatic AI-based prototype system that tracks annulus and apex landmarks by the registration network on time-resolved two- and four-chamber CMR cine views. Parameters such as displacements, velocities, mitral annular plane systolic excursion (MAPSE), or longitudinal shortening (LS) are automatically extracted and evaluated on a large CMR dataset (N=11000). Methods The system consists of two sequential neural networks with a processing step in between (Fig. 1a) [3]. Initially, a 2D UNet is applied to localize both MV annulus insertion points as well as the apex. Based on these points, the image processing step consists of rotating, cropping, and interpolating the images, allowing a standardized image impression for both long axis views. Finally, the registration network (VoxelMorph framework [4]) is applied to the processed series and tracks the MV annulus insertion points and apex over the cardiac cycle by the deformation fields obtained by the network. The system was trained on (N=166) multivendor, multi-field strength, ground-truth annotated datasets [5]. A total of 11000 datasets, acquired on a 1.5T scanner (MAGNETOM Aera, Siemens Healthcare, Erlangen, Germany) from January 2016 to September 2017 [6], were used for parameter extraction. 200 of these datasets were additionally annotated semi-automatically for the performance evaluation of the system. Five motion parameters were automatically derived by the system that are defined as follows (Fig. 1b): (1) The atrioventricular plane displacement (AVPD) as the distance of the plane spanned by the MV annulus points relative to the first frame, (2) the atrioventricular plane velocity (AVPV) as the discrete temporal derivate of the AVPD, (3) the diameter of the annulus as the maximum distance between the MV annulus points, (4) the lateral/inferior and septal/superior MAPSE, as the maximum MV points’ excursion, and (5) the LS as the percentage size difference of the distance between the mid valvular point and the apex point at end-systole and end-diastole. Results The accuracy of the system resulted in deviations on the annotated dataset of 1.02 ± 0.87 mm, 0.01 ± 0.02 mm/s, 1.54 ± 1.21 mm, 2.30 ± 1.35 mm, 2.1 ± 1.8 mm for AVPD, AVPV, diameter, MAPSE, and LS respectively. Initial statistics on all datasets (Fig. 2) revealed a mean lateral/inferior, septal/superior MAPSE and LS of 8.7 ± 2.7 mm, 10.5 ± 3.2 mm and 16.3 ± 4.2 % for two-chamber and 9.6 ± 2.6 mm, 8.7 ± 2.6 mm and 15.5 ± 3.9 % for four-chamber views, respectively. Conclusions The results demonstrate the versatility of the proposed system for automatic extraction of various MV motion parameters. The proposed system enables automatic extraction of clinically relevant parameters and can improve the automation of MV-based analyses. System overview &amp; Parameter of interestsAnalysis of the extracted parameters

Longitudinal changes in cardiac function in Duchenne muscular dystrophy population as measured by magnetic resonance imaging

BackgroundThe lack of dystrophin in cardiomyocytes in Duchenne muscular dystrophy (DMD) is associated with progressive decline in cardiac function eventually leading to death by 20–40 years of age. The aim of this prospective study was to determine rate of progressive decline in left ventricular (LV) function in Duchenne muscular dystrophy (DMD) over 5 years.MethodsShort axis cine and grid tagged images of the LV were acquired in individuals with DMD (n = 59; age = 5.3–18.0 years) yearly, and healthy controls at baseline (n = 16, age = 6.0–18.3 years) on a 3 T MRI scanner. Grid-tagged images were analyzed for composite circumferential strain (ℇcc%) and ℇcc% in six mid LV segments. Cine images were analyzed for left ventricular ejection fraction (LVEF), LV mass (LVM), end-diastolic volume (EDV), end-systolic volume (ESV), LV atrioventricular plane displacement (LVAPD), and circumferential uniformity ratio estimate (CURE). LVM, EDV, and ESV were normalized to body surface area for a normalized index of LVM (LVMI), EDV (EDVI) and ESV (ESVI).ResultsAt baseline, LV ℇcc% was significantly worse in DMD compared to controls and five of the six mid LV segments demonstrated abnormal strain in DMD. Longitudinal measurements revealed that ℇcc% consistently declined in individuals with DMD with the inferior segments being more affected. LVEF progressively declined between 3 to 5 years post baseline visit. In a multivariate analysis, the use of cardioprotective drugs trended towards positively impacting cardiac measures while loss of ambulation and baseline age were associated with negative impact. Eight out of 17 cardiac parameters reached a minimal clinically important difference with a threshold of 1/3 standard deviation.ConclusionThe study shows a worsening of circumferential strain in dystrophic myocardium. The findings emphasize the significance of early and longitudinal assessment of cardiac function in DMD and identify early biomarkers of cardiac dysfunction to help design clinical trials to mitigate cardiac pathology. This study provides valuable non-invasive and non-contrast based natural history data of cardiac changes which can be used to design clinical trials or interpret the results of current trials aimed at mitigating the effects of decreased cardiac function in DMD.

Anatomy for ablation of atrioventricular nodal reentry tachycardia and accessory pathways.

The atrioventricular (AV) valve plane and the central septum are of particular importance for electrophysiological diagnosis and interventional therapy of supraventricular tachycardias because accessory electrical connections of various types may be present in addition to the specific conduction system. Although modern 3D electroanatomic reconstruction systems including high-density mapping can be of great assistance, detailed knowledge of the anatomic structures involved, their complex three-dimensional arrangement, and their electrical properties in conjunction with electrophysiological features of supraventricular arrhythmias is essential for safe and efficient electrophysiological treatment. The aim of this article is to present current anatomical, topographical, and electrophysiological findings against the background of historical, seminal, and still indispensable literature.

Atrioventricular plane displacement and regional function to predict outcome in pulmonary arterial hypertension

To investigate if left and right atrioventricular plane displacement (AVPD) or regional contributions to SV are prognostic for outcome in patients with pulmonary arterial hypertension (PAH). Seventy-one patients with PAH and 20 sex- and age-matched healthy controls underwent CMR. Myocardial borders and RV insertion points were defined at end diastole and end systole in cine short-axis stacks to compute biventricular volumes, lateral (SVlat%) and septal (SVsept%) contribution to stroke volume. Eight atrioventricular points were defined at end diastole and end systole in 2-, 3- and 4-chamber cine long-axis views for computation of AVPD and longitudinal contribution to stroke volume (SVlong%). Cut-off values for survival analysis were defined as two standard deviations above or below the mean of the controls. Outcome was defined as death or lung transplantation. Median follow-up time was 3.6 [IQR 3.7] years. Patients were 57 ± 19 years (65% women) and controls 58 ± 15 years (70% women). Biventricular AVPD, SVlong% and ejection fraction (EF) were lower and SVlat% was higher, while SVsept% was lower in PAH compared with controls. In PAH, transplantation-free survival was lower below cut-off for LV-AVPD (hazard ratio [HR] = 2.1, 95%CI 1.2–3.9, p = 0.02) and RV-AVPD (HR = 9.8, 95%CI 4.6–21.1, p = 0.005). In Cox regression analysis, lower LV-AVPD and RV-AVPD inferred lower transplantation-free survival (LV: HR = 1.16, p = 0.007; RV: HR = 1.11, p = 0.01; per mm decrease). LV-SVlong%, RV-SVlong%, LV-SVlat%, RV-SVlat%, SVsept% and LV- and RVEF did not affect outcome. Low left and right AVPD were associated with outcome in PAH, but regional contributions to stroke volume and EF were not.

Prevalence and diagnostic value of extra-left ventricle echocardiographic findings in transthyretin-related cardiac amyloidosis

Background Cardiac amyloidosis (CA) is cardiomyopathy with a hypertrophic phenotype characterised by diffuse deposition of anomalous fibrillar proteins in the extracellular matrix. Objectives To evaluate the prevalence and diagnostic value of extra left ventricle echocardiographic findings in patients with left ventricular (LV) hypertrophic phenotype and amyloid deposition. Methods A group of 146 patients with LV thickness ≥15 mm were enrolled: 70 patients who received a definite diagnosis of sarcomeric hypertrophic cardiomyopathy (HCM group) and 76 patients with transthyretin cardiac amyloidosis (CA group). Echocardiographic analysis of crista terminalis (CriT), atrio-ventricular plane (AVP), mitro-aortic lamina (MAL), anterior ascending aortic wall, interatrial septum (IAS), Eustachian valve (EusV) and coumadin ridge (CouR) was performed in all patients, and these structures were compared among the two groups. Results CA group showed significantly higher dimensions of CriT, IAS, CouR, AVP, MAL and IAS compared to the HCM group. The logistic analysis showed that LV EF, LV septal thickness, CriT presence, CriT area, MAL and IAS were all predictors of CA in univariate analyses. The stepwise multivariate analysis showed independent predictors of CA: CriT area, MAL and LVEF. According to areas under the receiver operating characteristic curves the best cut-off values to determine CA were identified (IAS > 9 mm, MAL > 7 mm, CriT > 9 mm2). Among these 3 independent predictors, IAS > 9 mm had the best specificity (96%) and positive predictive value (93%) in identifying CA. Conclusions evidence of extra left ventricle sites of amyloid deposition is a frequent finding in CA. In the context of hypertrophic phenocopies, an increased thickness of IAS, and/or CT and/or MAL should suggest a diagnosis of transthyretin CA.

Ventricular longitudinal function by cardiovascular magnetic resonance predicts cardiovascular morbidity in HFrEF patients.

AimsVentricular longitudinal function measured as basal‐apical atrioventricular plane displacement (AVPD) or global longitudinal strain (GLS) is a potent predictor of mortality and could potentially be a predictor of heart failure‐associated morbidity. We hypothesized that low AVPD and GLS are associated with the combined endpoint of cardiovascular mortality and heart failure‐associated morbidity.Methods and resultsTwo hundred eighty‐seven patients (age 62 ± 12 years, 78% male) with heart failure with reduced (≤40%) ejection fraction (HFrEF) referred to a cardiovascular magnetic resonance exam were included. Ventricular longitudinal function, ventricular volume, and myocardial fibrosis or infarction were analysed from cine and late gadolinium enhancement images. National registries provided data on causes of cardiovascular hospitalizations and cardiovascular mortality for the combined endpoint. Time‐to‐event analysis capable of including reoccurring events was employed with a 5‐year follow‐up. HFrEF patients had EF 26.5 ± 8.0%, AVPD 7.8 ± 2.4 mm, and GLS −7.5 ± 3.0%. In contrast, ventricular longitudinal function was approximately twice as large in an age‐matched control group (AVPD 15.3 ± 1.6 mm; GLS −20.6 ± 2.0%; P < 0.001 for both). There were 578 events in total, and the majority were HF hospitalizations (n = 418). Other major events were revascularizations (n = 64), cardiovascular deaths (n = 40), and myocardial infarctions (n = 21). One hundred fifty‐five (54%) patients experienced at least one event (mean 2.0, range 0–64). Of these patients, 119 (71%) had three events or fewer, and the first three events comprised 51% of all events (295 events). Patients in the bottom AVPD or GLS tertile (<6.8 mm or >−6.1%) overall experienced more than 3 times as many events as the top tertile (>8.8 mm or <−8.4%; P < 0.001). Patients in this tertile also faced more cardiovascular deaths (P < 0.05), HF hospitalizations (P = 0.001), myocardial infarctions (only GLS: P = 0.032), and accumulated longer in‐hospital length‐of‐stay overall (AVPD 20.9 vs. 9.1 days; GLS 22.4 vs. 6.5 days; P = 0.001 for both), and from HF hospitalizations (AVPD 19.3 vs. 8.3 days; GLS 19.3 vs. 5.4 days; P = 0.001 for both). In multivariate analysis adjusted for significant covariates, AVPD and GLS remained independent predictors of events (hazard ratio 1.12 per‐mm‐decrease and 1.13 per‐%‐increase) alongside hyponatremia (<135 mmol/L), aetiology of HF, and LV end‐diastolic volume index.ConclusionsLow ventricular longitudinal function is associated with an increase in number of events as well as longer in‐hospital stay from cardiovascular causes. In addition, AVPD and GLS have independent prognostic value for cardiovascular mortality and morbidity in HFrEF patients.

Single cardiomyocytes from papillary muscles show lower preload-dependent activation of force compared to cardiomyocytes from the left ventricular free wall

Efficient pumping of the healthy left ventricle (LV) requires heterogeneities in mechanical function of individual cardiomyocytes (CM). Deformation of sub-endocardial (Endo) tissue is greater than that of sub-epicardial (Epi) regions. Papillary muscles (PM), often considered to be part of Endo tissue, show lower beat-by-beat length variation than Epi (or Endo) regions, even though they contribute to the shift in atrio-ventricular valve plane, which is essential for LV pump function. Thus far, no comparative assessment of CM mechanics for PM and LV free wall has been published.Here, we investigate contractility and cytosolic calcium concentration ([Ca2+]c) transients in rabbit single CM, freshly isolated from PM, Endo and Epi regions of the LV (free wall tissue was further subdivided into near-basal [Base], equatorial [Centre], and near-apical [Apex] parts). Functional parameters were measured in the absence of external mechanical loads (non-loaded), or during afterloaded (auxotonic) CM contractions, initiated from different levels of preload (diastolic axial stretch), using the carbon fibre technique.We note significant differences in time-course and amplitudes of sarcomere shortening between PM, Endo and Epi CM. In non-loaded CM, sarcomere shortening between regions compares as follows: Endo > Epi and Endo > PM. During afterloaded contractions, the slope of auxotonic tension-length relation and the Frank-Starling gain index (preload-dependent increase in tension and shortening) follow the sequence of Endo > Epi > PM. In terms of apico-basal gradients, time-to-peak sarcomere shortening was greater in Apex compared to Centre and Base in non-loaded CM only.Thus, CM from PM show the least pronounced preload-dependent activation of force across the LV regions assessed, while CM from Endo regions show the strongest response. This is in keeping with prior in situ observations on the smaller extent of PM shortening and their thus lower functional requirement for sensitivity to preload, compared to LV free wall. The here identified regional differences in cellular Frank-Starling responses illustrate the extent to which CM mechanical responses appear to be in keeping with in situ differences in mechanical demand.

The impact of isometric handgrip testing in left atrial reservoir function

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Fundação Adib Jatene Background Speckle tracking echocardiography (STE) allows accurate quantification of left atrial (LA) strain, thus allowing assessment of all phases of LA function (reservoir, conduit and contraction). Alterations in LA strain occur before changes in LA volumes, enabling early detection of LA dysfunction. In particular, the peak of LA strain during the reservoir phase (LASr) seems to be of prognostic value in heart failure. LASr is essential to pool enough blood volume to fill the LV during the subsequent diastole. The main determinants of LA reservoir function include blood volume arriving from the right ventricle, LA relaxation, and LA compliance. Still, changes in atrioventricular plane movement during the ventricular systole have been considered an additional factor influencing LASr. The relative contribution of left ventricular afterload to LASr, however, has yet to be clearly defined. Purpose We aimed to study the LA function during changes in LV afterload induced by the handgrip maneuver in subjects without heart disease, applying LASr and strain curve shape analysis. Material and Methods We studied 31 subjects (47 ± 15 years) without evidence of heart disease. A comprehensive 2D echocardiography was performed. We recorded 3 beat clips with standard STE views of LV and LA in baseline conditions and then during pressure overload-induced by left handgrip (42 ± 8 kg) combined with simultaneous pneumatic constriction of the right arm and both lower limbs. The LV GLS and LASr were calculated offline by a blinded examinator using commercially available software. Furthermore, we extracted the raw data of the strain curves and post-processed these signals using custom software. The global curves were split into different cardiac cycle phases using the valve opening and closure times(Figure 1). Quadratic functions estimated strain curves during the ejection phase due to the acceleration involved in the phenomenon. Quadratic function linear coefficients, a component of strain rate, were used to assess the shape of deformation curves. Results The handgrip maneuver caused mild reductions in LV strain: GLS baseline –19.07 % (±0.27) vs GLS handgrip -18.58% (±0.26) p = 0.02 (Figure 2A and C). Conversely, the LASr did not present significant changes: LASr baseline 33.82% (±0.84) vs LASr handgrip 32.96% (±0.85) p= 0.18 (Figure 2B and C). For the analysis of the shape of strain curves, we obtained data from 29 subjects. We found significant differences in LV ejection linear coefficient (ELC): LV ELC baseline –158.30 (±8.52) vs LV ELC handgrip –144.62 (±8.02) p = 0.02. For LA reservoir linear coefficient (RLC), we also found significant differences: LA RLC baseline 240.30 (±17.19) vs LA RLC handgrip 212.61 (±15.62) p = 0.03 (Figure 2D). Conclusion(s) The left atrial reservoir function is affected by changes in LV afterload induced by the handgrip maneuver. Our data suggest that LV pressure overload mainly impact the shape of LA strain curve rather than LASr. Abstract Figure 1 Abstract Figure 2

Non-Specialised Medical Staff Assessing Left Ventricular Systolic Function by Measuring Mitral Annular Excursion via Hand-Held Echocardiography Device and Automated Atrioventricular-Plane Tracking Algorithm

Increased portability and automation of echocardiography provides potential for point-of-care, focussed assessments. Screening for left ventricular systolic dysfunction via non-specialised staff is now a real possibility. Determine accuracy and feasibility of first-in-man technology, mitral annular excursion (MAE) via hand-carried ultrasound (HCU; integrated with an automatic atrio-ventricular plane algorithm ‘AutoMAE’) performed by non-specialised medical staff. Three junior doctors (no prior experience in echocardiography) completed brief didactic lectures followed by practical training in 10 practice patients. A cardiac sonographer and the three doctors then performed HCU AutoMAE (AV plane App on Vscan ExtendTM; apical four chamber orientation) on consecutive patients with echocardiography performed clinically <24hrs; all with feasible image quality and in sinus rhythm. AutoMAE measures (junior doctors and sonographer) were compared to standard echocardiographic Biplane LVEF (BPLVEF) using receiver-operator characteristic (binary classification 50% BPLVEF; criterion cut-off 9mm MAE); mean difference with bias analyses were also performed. Collective junior doctor performed cohort was n=44 (58±14yrs; 64% male; BPLVEF 55±12%), with doctor-specific subcohorts (#1-#3) demonstrating good feasibility 82-86%. Sonographer cohort (n=36; 59±14yrs; 64% male; biplane LVEF 55±11%) demonstrated 94% feasibility. Doctor subcohorts AutoMAE measures (pairwise) found mean difference /bias (mm) at 1.6/-0.1, 1.0/-0.3 and 1.7/+0.1 (respectively) when compared to sonographer AutoMAE. Non-specialised junior doctors performing HCU AutoMAE assessment after brief training is accurate and feasible. This could permit monitoring for left ventricular systolic dysfunction in high-risk patient cohorts.Tabled 1CohortCollective DrSonographerDr #1Dr #2Dr #3Cohort % with BPLVEF ≤50%27%31%23%28%17%Area under Curve0.850.910.840.860.90Sensitivity93%85%97%93%100%Specificity64%84%63%64%74% Open table in a new tab

A Fully-Coupled Electro-Mechanical Whole-Heart Computational Model: Influence of Cardiac Contraction on the ECG.

The ECG is one of the most commonly used non-invasive tools to gain insights into the electrical functioning of the heart. It has been crucial as a foundation in the creation and validation of in silico models describing the underlying electrophysiological processes. However, so far, the contraction of the heart and its influences on the ECG have mainly been overlooked in in silico models. As the heart contracts and moves, so do the electrical sources within the heart responsible for the signal on the body surface, thus potentially altering the ECG. To illuminate these aspects, we developed a human 4-chamber electro-mechanically coupled whole heart in silico model and embedded it within a torso model. Our model faithfully reproduces measured 12-lead ECG traces, circulatory characteristics, as well as physiological ventricular rotation and atrioventricular valve plane displacement. We compare our dynamic model to three non-deforming ones in terms of standard clinically used ECG leads (Einthoven and Wilson) and body surface potential maps (BSPM). The non-deforming models consider the heart at its ventricular end-diastatic, end-diastolic and end-systolic states. The standard leads show negligible differences during P-Wave and QRS-Complex, yet during T-Wave the leads closest to the heart show prominent differences in amplitude. When looking at the BSPM, there are no notable differences during the P-Wave, but effects of cardiac motion can be observed already during the QRS-Complex, increasing further during the T-Wave. We conclude that for the modeling of activation (P-Wave/QRS-Complex), the associated effort of simulating a complete electro-mechanical approach is not worth the computational cost. But when looking at ventricular repolarization (T-Wave) in standard leads as well as BSPM, there are areas where the signal can be influenced by cardiac motion of the heart to an extent that should not be ignored.

Abstract 14088: Ventricular Longitudinal Function by CMR Predicts Heart Failure Associated Morbidity in Patients With Heart Failure and Reduced Ejection Fraction

Ventricular longitudinal function measured as basal-apical atrioventricular plane displacement (AVPD) or global longitudinal strain (GLS) are potent predictors of mortality and could potentially be predictors of morbidity in heart failure (HF). We hypothesize that decreased AVPD and GLS are associated with increased morbidity measured. Patients with HFrEF (EF≤40%) referred to a CMR exam were considered for inclusion. Ventricular longitudinal function, ventricular volumes and myocardial fibrosis or infarctions were analyzed. National registries provided data on cause of cardiovascular hospitalizations and cardiovascular mortality and this was used as a composite endpoint. A time-to-event analysis capable of including reoccurring events were employed with 5-year follow-up. HFrEF patients (n=287, age 62±12, 78% male) had EF 26.5% (SEM 0.5), AVPD 7.8 mm (SEM 0.1) and GLS -7.5% (SEM 0.2). There were 578 events in total and the vast majority was HF hospitalizations (n=418). Other major events were revascularizations (n=64), cardiovascular deaths (n=40) and myocardial infarctions (n=21), and 155 (54%) patients experienced at least one event (Mean 2.0, range 0-64). Patients in the bottom AVPD or GLS tertile (&lt;6.8mm or &gt;-6.1%) experienced over 3 times as many events compared to the top tertile (&gt;8.8 mm or &lt;-8.4%, p&lt;0.001) (Figure 1). In multivariate analysis adjusted for significant variables, AVPD and GLS remained as independent predictors of events (HR 1.12 per-mm-decrease and HR 1.13 per-%-increase) (Table 1). In conclusion, ventricular longitudinal function, measured either as AVPD or GLS, have independently prognostic implications for morbidity in HFrEF patients.

Regional contributions to left ventricular stroke volume determined by cardiac magnetic resonance imaging in cardiac resynchronization therapy

BackgroundCardiac resynchronization therapy (CRT) restores ventricular synchrony and induces left ventricular (LV) reverse remodeling in patients with heart failure (HF) and dyssynchrony. However, 30% of treated patients are non-responders despite all efforts. Cardiac magnetic resonance imaging (CMR) can be used to quantify regional contributions to stroke volume (SV) as potential CRT predictors. The aim of this study was to determine if LV longitudinal (SVlong%), lateral (SVlat%), and septal (SVsept%) contributions to SV differ from healthy controls and investigate if these parameters can predict CRT response.MethodsSixty-five patients (19 women, 67 ± 9 years) with symptomatic HF (LVEF ≤ 35%) and broadened QRS (≥ 120 ms) underwent CMR. SVlong% was calculated as the volume encompassed by the atrioventricular plane displacement (AVPD) from end diastole (ED) to end systole (ES) divided by total SV. SVlat%, and SVsept% were calculated as the volume encompassed by radial contraction from ED to ES. Twenty age- and sex-matched healthy volunteers were used as controls. The regional measures were compared to outcome response defined as ≥ 15% decrease in echocardiographic LV end-systolic volume (LVESV) from pre- to 6-months post CRT (delta, Δ).ResultsAVPD and SVlong% were lower in patients compared to controls (8.3 ± 3.2 mm vs 15.3 ± 1.6 mm, P < 0.001; and 53 ± 18% vs 64 ± 8%, P < 0.01). SVsept% was lower (0 ± 15% vs 10 ± 4%, P < 0.01) with a higher SVlat% in the patient group (42 ± 16% vs 29 ± 7%, P < 0.01). There were no differences between responders and non-responders in neither SVlong% (P = 0.87), SVlat% (P = 0.09), nor SVsept% (P = 0.65). In patients with septal net motion towards the right ventricle (n = 28) ΔLVESV was − 18 ± 22% and with septal net motion towards the LV (n = 37) ΔLVESV was − 19 ± 23% (P = 0.96).ConclusionsLongitudinal function, expressed as AVPD and longitudinal contribution to SV, is decreased in patients with HF scheduled for CRT. A larger lateral contribution to SV compensates for the abnormal septal systolic net movement. However, LV reverse remodeling could not be predicted by these regional contributors to SV.