Force-frequency Relationship and Post-extrasystolic Potentiation Detection

Rationale: Heart failure (HF) is a clinical condition affecting 1-2% of the population in the Western world. In systolic HF, the contractile performance of the heart is reduced causing low cardiac output. This is traditionally measured by means of imaging technologies such as nuclear imaging, MRI or ultrasound and expressed as ejection fraction (EF). In clinical practice, this remains a poor parameter as symptoms and prognosis only marginally correlate with EF; moreover, it does not allow constant therapy optimization or prediction of imminent adverse events.
Systolic functioning of the myocardium can also be studied with the concepts of force-frequency relationship (FFR) and force-interval relationship of the heart. Force-frequency and force-interval relationships describe the changes in the contractile force of the heart in relation to the changes of the stimulation rate. In normal FFR, contractility increases at higher heart rates; this phenomenon is reduced or leveled off in heart failure. Post-extrasystolic potentiation (PESP) is a concept of force-interval relationship in which the contractility of the heart increases for the beat following the compensatory pause after an extrasystolic beat. Several studies have shown an enhanced PESP in the HF population when compared to patients with a non-failing heart. FFR and PESP could be used as diagnostic tools and prognostic markers in heart failure patients. The above studies have been mainly conducted by using invasive measures. Philips Research has developed wearable technology based on photoplethysmography (PPG) which is an unobtrusive measurement of blood volume changes in the tissue. The aim of this study is to explore if the PPG-waveform can be correlated with invasive arterial blood pressure (ABP) and whether it can be used for detecting PESP and FFR.
Objective: The objectives of this study are to acquire PPG data in patients during an ablation procedure simultaneously with reference measurements (ECG, ABP), investigate differences in PPG measurement between patients with failing and non-failing hearts, and to develop methods to detect PESP and FFR from PPG.
Study design: The study is an observational study.
Study population: Twenty adult patients to be treated with ablation for premature ventricular contractions and/or ventricular tachycardia: 10 patients with left ventricular ejection fraction (LVEF) < 40% and 10 patients with LVEF >= 50%.
Main study parameters/endpoints: The main study parameters are simultaneous ECG, ABP, PPG, and accelerometer recordings that can be used to study differences between patients with failing and non-failing hearts.
Nature and extent of the burden and risks associated with participation, benefit and group relatedness: In the study, ECG, ABP, PPG, and accelerometer data will be collected during a pre-defined stimulation protocol before ablation and during the cardiac ablation procedure itself. In every ablation procedure, cardiac stimulation protocols are used to induce arrhythmias. These stimulation protocols depend on the clinical problem and the patient’s condition. The study protocol is similar to the standard procedural protocols; additional stimulation manoeuvres for the study is left to the discretion of the treating physician. Wearing the Elan to collect PPG and accelerometer data during the procedures are additional to the usual/standard clinical care.
During cardiac pacing, arrhythmias can occur, as this is the purpose of the procedure. It speaks for itself that patients and personnel are aware of this, and are trained and prepared for adequate treatment. We therefore conclude that there are no additional risks associated with this study. Most of the study does not interfere with usual clinical care. The only addition will be wearing the Elan wristband and a short pacing protocol (up to 10 minutes) that is not part of usual/standard clinical care. The burden for all the patients volunteering in the study is considered minimal.

Using Force-frequency relationship and post-extrasystolic potentiation measured by photoplethysmography at the wrist is able to accurately differentiate failing hearts from non-failing hearts

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