Use of cardiac muscle sounds to optimize cardiac resynchronization therapy
A pilot study of the potential application of cardiac muscle sounds to optimize cardiac resynchronization therapy in patients with heart failure
Duration of Study in the UK
1 years, 8 months, 25 days
Summary of Research
Heart failure is a leading cause of deaths and hospital admissions. In heart failure, dyssynchronous (not moving together in synchrony) movement of the different chambers of the heart can reduce the heart’s efficiency as a pump to supply blood to the rest of the body, resulting in symptoms such as breathlessness.
Cardiac resynchronisation therapy (CRT) is use of a special type of pacemaker for patients with advanced heart failure who do not respond to medications. CRT works by electrically stimulating the heart muscle in different chambers of the heart to contract (with pacemaker leads connected to a pacemaker box) in synchrony and therefore improve pump efficiency.
However, a third of patients do not respond well to CRT. Commonly, this may be due to incorrect pacemaker settings. Getting the settings right, called CRT optimisation, usually requires echocardiography (ultrasound imaging of the heart) and access to this is highly dependent on availability of local expertise.
There is scientific evidence that heart muscle sound vibrations generated from contraction of the heart muscle can tell us how efficiently the heart works as a pump.
Our primary objective is to investigate the feasibility of using cardiac muscle sounds recorded from outside the chest to identify non-responders to CRT and to guide adjustment of CRT pacemaker settings instead of using echocardiography. This could potentially be a non-invasive, more affordable and accessible method of CRT optimisation that enables more patients to have the best pacemaker settings for their needs.
We propose to record heart muscle sounds externally with a sound recording system in patients diagnosed with heart failure who have been referred for CRT optimisation with echocardiography. We also propose to study the efficacy of CRT optimization in improving long term response to CRT in a prospective cohort of initial non-responders to CRT to support current clinical practice.
Summary of Results
1) 96 participants were recruited in total with heart sounds recorded with an electronic (e-) stethoscope at the first visit. 37 participants had normal heart function and 59 participants had heart failure with reduced ejection fraction of the left ventricle. 48 patients with heart failure had heart sounds recorded with an e-stethoscope before they underwent implant of cardiac resynchronization therapy (CRT) pacemaker or defibrillator and at follow up visits in the device clinic.
2) Algorithms had been developed through collaboration with biomedical engineers to process the signals of heart sounds obtained from e-stethoscope for analysis of acoustic features.
3) Participants without heart failure had different acoustic features from those with impaired left ventricular function.
4) There was correlation between acoustic features obtained from e-stethoscope and non-invasive measures of heart function.
5) Some of the above acoustic features also correlate with measures of heart function on echocardiogram, when these were analyzed during optimization of CRT-devices in patients with heart failure
6) In patients whose heart sound recordings had good signal to noise ratio, the optimal value of CRT settings predicted by acoustic features was similar to that obtained from echocardiography, which is a more time-consuming method often used in clinical practice currently.
East Midlands - Leicester Central Research Ethics Committee
Date of REC Opinion
28 Jan 2015
Further Information Favourable Opinion