Continuous and Autonomous Monitoring of Changes in Left Ventricular dP/dt Using an Epicardial Accelerometer.

Assessment of the contractile function of the heart typically requires resource demanding techniques, such as invasive left ventricular catheterisation or intermittent medical imaging, and is therefore not readily available for continuous clinical or remote monitoring. Measurement of heart wall motion by use of an epicardially attached three-axis accelerometer has emerged as a promising tool for monitoring cardiac function; however, previous methods have often underutilised the spatial and temporal information contained in the measured signals, potentially limiting its clinical reliability. This work reconstructs the position of an epicardial accelerometer in 3D space in order to enable extraction of indices of cardiac function in a Lagrangian frame of reference.

Noninvasive Pressure-Volume Analysis by Three-Dimensional Echocardiography: A Novel Powerful Method for Evaluating Left Ventricular Function.

Background: Pressure-volume (PV) analysis is the gold standard for evaluating left ventricular (LV) function but is rarely used clinically due to its invasiveness. We validated a noninvasive method for PV analysis by three-dimensional (3D) echocardiography against invasive reference measurements and a novel index of LV efficiency against LV efficiency derived from metabolism by positron emission tomography-computed tomography (PET-CT).

Methods: In 22 canines, LV volume was measured invasively using piezoelectric crystals and LV pressure by micromanometer.

Deep neural network valve detection for accelerometer based cardiac monitoring.

Miniaturized accelerometers incorporated in pacing leads attached directly onto the heart provide a means for continuous monitoring of cardiac function. Several functional accelerometer indices first require detection of valve events. We previously developed a deep neural network to detect timing of aortic valve closure and opening.

Imaging-based method to quantify left ventricular diastolic pressures.

Aims: To establish an imaging-based method to quantify left ventricular (LV) diastolic pressures.

Methods And Results: In 115 patients suspected of coronary artery disease, LV pressure was measured by micromanometers and images by echocardiography. LV filling pressure was measured as LV pre-atrial contraction pressure (pre-A PLV).

Mechanism and Impact of Left Atrial Dyssynchrony on Long-Term Clinical Outcome During Cardiac Resynchronization Therapy.

Background: Left bundle branch block (LBBB) causes left atrial (LA) dyssynchrony. It is unknown if LA dyssynchrony impacts long-term prognosis.

Objectives: The purpose of this study was to determine mechanisms of LA dyssynchrony in LBBB and if LA dyssynchrony impacts long-term prognosis.

Asymmetric right ventricular myocardial work correlates with gold standard measurements of cardiac function in pulmonary hypertension.

Right ventricular (RV) (dys)function determines outcomes in pulmonary hypertension (PH). We previously found that asymmetric RV myocardial work (MW) corresponds with inefficient RV function in experimental PH models. We therefore aimed to investigate regional distribution of RV MW and its correlation with catheter hemodynamics in children with PH.

Myocardial Strain Imaging: Theory, Current Practice, and the Future.

Myocardial strain imaging by echocardiography or cardiac magnetic resonance (CMR) is a powerful method to diagnose cardiac disease. Strain imaging provides measures of myocardial shortening, thickening, and lengthening and can be applied to any cardiac chamber. Left ventricular (LV) global longitudinal strain by speckle-tracking echocardiography is the most widely used clinical strain parameter.

Evaluation of left ventricular filling pressure by echocardiography in patients with atrial fibrillation.

Background: Echocardiography is widely used to evaluate left ventricular (LV) diastolic function in patients suspected of heart failure. For patients in sinus rhythm, a combination of several echocardiographic parameters can differentiate between normal and elevated LV filling pressure with good accuracy. However, there is no established echocardiographic approach for the evaluation of LV filling pressure in patients with atrial fibrillation.

Cardiac Valve Event Timing in Echocardiography Using Deep Learning and Triplane Recordings.

Cardiac valve event timing plays a crucial role when conducting clinical measurements using echocardiography. However, established automated approaches are limited by the need of external electrocardiogram sensors, and manual measurements often rely on timing from different cardiac cycles. Recent methods have applied deep learning to cardiac timing, but they have mainly been restricted to only detecting two key time points, namely end-diastole (ED) and end-systole (ES).

Association between myocardial work indices and cardiovascular events according to hypertension in the general population.

Aims: Pressure-strain loop (PSL) analysis is a novel echocardiographic tool capable of assessing myocardial work non-invasively. In this study, we aim to evaluate the prognostic value of myocardial work indices in the general population.

Methods And Results: This was a prospective community-based cohort study (n = 4466).

Non-invasive myocardial work in aortic stenosis: validation and improvement in left ventricular pressure estimation.

Aims: The non-invasive myocardial work index (MWI) has been validated in patients without aortic stenosis (AS). A thorough assessment of methodological limitations is warranted before this index can be applied to patients with AS.

Methods And Results: We simultaneously measured left ventricular pressure (LVP) by using a micromanometer-tipped catheter and obtained echocardiograms in 20 patients with severe AS.

Pulse arrival time variation as a non-invasive marker of acute response to cardiac resynchronization therapy.

Aims: Successful cardiac resynchronization therapy (CRT) shortens the pre-ejection period (PEP) which is prolonged in the left bundle branch block (LBBB). In a combined animal and patient study, we investigated if changes in the pulse arrival time (PAT) could be used to measure acute changes in PEP during CRT implantation and hence be used to evaluate acute CRT response non-invasively and in real time.

Methods And Results: In six canines, a pulse transducer was attached to a lower limb and PAT was measured together with left ventricular (LV) pressure by micromanometer at baseline, after induction of LBBB and during biventricular pacing.

Tracking Early Systolic Motion for Assessing Acute Response to Cardiac Resynchronization Therapy in Real Time.

An abnormal systolic motion is frequently observed in patients with left bundle branch block (LBBB), and it has been proposed as a predictor of response to cardiac resynchronization therapy (CRT). Our goal was to investigate if this motion can be monitored with miniaturized sensors feasible for clinical use to identify response to CRT in real time. Motion sensors were attached to the septum and the left ventricular (LV) lateral wall of eighteen anesthetized dogs.

Automatic Detection of Aortic Valve Events Using Deep Neural Networks on Cardiac Signals From Epicardially Placed Accelerometer.

Background: Miniaturized accelerometers incorporated in pacing leads attached to the myocardium, are used to monitor cardiac function. For this purpose functional indices must be extracted from the acceleration signal. A method that automatically detects the time of aortic valve opening (AVO) and aortic valve closure (AVC) will be helpful for such extraction.

A high-throughput study of visceral organs in CT-scanned pigs.

It has been debated whether intensive selection for growth and carcass yield in pig breeding programmes can affect the size of internal organs, and thereby reduce the animal's ability to handle stress and increase the risk of sudden deaths. To explore the respiratory and circulatory system in pigs, a deep learning based computational pipeline was built to extract the size of lungs and hearts from CT-scan images. This pipeline was applied on CT images from 11,000 boar selection candidates acquired during the last decade.

Normal Values for Myocardial Work Indices Derived From Pressure-Strain Loop Analyses: From the CCHS.

Background: Pressure-strain loop analyses is a noninvasive technique capable of evaluating myocardial work. Reference values are needed to benchmark these myocardial work indices for clinical practice.

Methods: Healthy participants from a general population study were used to establish reference values for global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) measured by pressure-strain loop analyses.

Shortening of time-to-peak left ventricular pressure rise (Td) in cardiac resynchronization therapy.

Aims: We tested the hypothesis that shortening of time-to-peak left ventricular pressure rise (Td) reflect resynchronization in an animal model and that Td measured in patients will be helpful to identify long-term volumetric responders [end-systolic volume (ESV) decrease >15%] in cardiac resynchronization therapy (CRT).

Methods: Td was analysed in an animal study (n = 12) of left bundle-branch block (LBBB) with extensive instrumentation to detect left ventricular myocardial deformation, electrical activation, and pressures during pacing. The sum of electrical delays from the onset of pacing to four intracardiac electrodes formed a synchronicity index (SI).

Lateral Wall Dysfunction Signals Onset of Progressive Heart Failure in Left Bundle Branch Block.

Objectives: This study sought to investigate if contractile asymmetry between septum and left ventricular (LV) lateral wall drives heart failure development in patients with left bundle branch block (LBBB) and whether the presence of lateral wall dysfunction affects potential for recovery of LV function with cardiac resynchronization therapy (CRT).

Background: LBBB may induce or aggravate heart failure. Understanding the underlying mechanisms is important to optimize timing of CRT.