Haemodynamic monitoring of cardiac status using heart sounds from an implanted cardiac device

Abstract

AimThe aim of this study was to evaluate the haemodynamic correlates of heart sound (HS) parameters such as third HS (S3), first HS (S1), and HS‐based systolic time intervals (HSTIs) from an implantable cardiac device.Methods and resultsTwo unique animal models (10 swine with myocardial ischaemia and 11 canines with pulmonary oedema) were used to evaluate haemodynamic correlates of S1, S3, and HSTIs, namely, HS‐based pre‐ejection period (HSPEP), HS‐based ejection time (HSET), and the ratio HSPEP/HSET during acute haemodynamic perturbations. The HS was measured using implanted cardiac resynchronization therapy defibrillator devices simultaneously with haemodynamic references such as left atrial (LA) pressure and left ventricular (LV) pressure. In the ischaemia model, S1 amplitude (r = 0.76 ± 0.038; P = 0.002), HSPEP (r = −0.56 ± 0.07; P = 0.002), and HSPEP/HSET (r = −0.42 ± 0.1; P = 0.002) were significantly correlated with LV dP/dtmax. In contrast, HSET was poorly correlated with LV dP/dtmax (r = 0.14 ± 0.14; P = 0.23). In the oedema model, a physiological delayed response was observed in S3 amplitude after acute haemodynamic perturbations. After adjusting for the delay, S3 amplitude significantly correlated with LA pressure in individual animals (r = 0.71 ± 0.07; max: 0.92; min: 0.17) as well as in aggregate (r = 0.62; P < 0.001). The S3 amplitude was able to detect elevated LA pressure, defined as >25 mmHg, with a sensitivity = 58% and specificity = 90%.ConclusionsThe HS parameters such as S1, S3, and HSTIs measured using implantable devices significantly correlated with haemodynamic changes in acute animal models, suggesting potential utility for remote heart failure patient monitoring.

Preliminary experience with a novel Multisensor algorithm for heart failure monitoring: The HeartLogic index

“…Specifically, the third heart sound is detected in order to provide an objective measure of elevated filling pressure, while the first heart sound is taken as a surrogate for left ventricular contractility, as it has been shown to correlate with the maximum pressure derivative. 4 In agreement with previous studies, 5 we also observed higher values of respiratory rate at the time of HF events. Moreover, the continuous measurement of resting heart rate, in addition to its contribution to HeartLogic index calculation, allowed us to detect the recovery of fast atrioventricular conduction, therefore suggesting the need to implement new solutions in order to control the rate and ensure biventricular pacing delivery.…”

“…Specifically, the third heart sound is detected in order to provide an objective measure of elevated filling pressure, while the first heart sound is taken as a surrogate for left ventricular contractility, as it has been shown to correlate with the maximum pressure derivative 4. In agreement with previous studies,5 we also observed higher values of respiratory rate at the time of HF events.…”

Ambulatory Monitoring of Heart Sounds via an Implanted Device Is Superior to Auscultation for Prediction of Heart Failure Events

“…The ability to measure S3 using sensors in implantable cardiac devices helps to overcome weaknesses by continuously monitoring S3 amplitudes, including both audible and subaudible components, and by providing objective quantification. An earlier canine study 6 demonstrated that devS3 is significantly correlated with changes in LAP and can detect elevated LAP with a specificity of 88%. This is consistent with a prior study 12 showing that phonocardiographic S3 amplitude is highly specific in detecting elevated left ventricular end-diastolic pressure in patients undergoing left-sided heart catheterization.…”

“…The device-measured heart sound (HS) signals have been shown to be feasible 5 and to be correlated with physiologic signals relevant to HF pathophysiology. 6 In an animal model, devS3 was significantly correlated with left atrial pressure (LAP) and was able to detect elevated LAP with high specificity. 6 However, it is unclear how well devS3 relates to traditional ausS3 and whether it is prognostic in ambulatory patients with HF.…”

“…6 In an animal model, devS3 was significantly correlated with left atrial pressure (LAP) and was able to detect elevated LAP with high specificity. 6 However, it is unclear how well devS3 relates to traditional ausS3 and whether it is prognostic in ambulatory patients with HF. This analysis aimed to explore the relationship between ausS3 and devS3 in patients with chronic HF and to compare their prognostic powers in identifying the risk of impending worsening HF.…”