Hemodynamic Monitoring with an Implantable Pressure Monitor is Improved by Additional Detection of Heart Sounds

Abstract

Early diagnosis of cardiac decompensation is essential to improve therapy of heart failure as one of the most costintensive chronic diseases worldwide. This can be achieved by remote monitoring of pulmonary artery pressure. An implantable pressure sensor system is developed in a joint research project (COMPASS), funded by the BMBF. The application of pulse contour analysis, which is well established for stroke volume estimation based on aortic blood pressure, to pulmonary artery pressure (PAP) is challenging due to different signal morphology and limited signal resolution. Especially the incisure in the pressure signal which marks valve closure is often not visible. Therefore, it was investigated whether valve closure can be detected by additional use of heart sounds more reliably. Blood pressure of an anesthetized Rhoen sheep was measured in the pulmonary artery with the implantable pressure monitor COMPASS and, for reference, additionally with commercial pressure catheters (Millar Instruments) in the pulmonary artery, aorta, left and right ventricles. Heart sounds were detected with a 3D accelerometer fixed at the animal's chest. For reference, valve opening and closure were derived from left ventricular pressure. With PAP only, 6.3% of all cardiac cycles were unusable for PCA at low and medium heart rates, as either valve opening or closure were missed or not correctly identified. At very high heart rates the loss rate increased up to 87%. When both PAP and accelerometer data were used, the loss rate was reduced to 0.1% … 0.4% for all heart rates. Combining blood pressure analysis with heart sounds improves the detection of valve opening and closure and thus SV estimation, especially at high heart rates.

Study of the Correlation Between the Ratio of Diastolic to Systolic Durations and Echocardiography Measurements and Its Application to the Classification of Heart Failure Phenotypes

“…For patients with CHF, cardiac dysfunction is a consequence of progressively impaired cardiac contractility 17 coupled with abnormal haemodynamic conditions. Since the monitoring of systolic and diastolic durations can reflect cardiac haemodynamics, 18 there is also accumulating evidence that systole and diastole are fundamental to the coronary flow reserve because the functional systolic and diastolic reserves are decreased, even in the early subclinical stages of cardiac dysfunction. 19 , 20 Nevertheless, the durations of systole and diastole are not routinely evaluated for different CHF subtypes.…”

Ongoing Development and First Long-Term Trials of a Cardiac Output Monitoring System in the Pulmonary Artery (Compass)

“…Therefore, a stimulation catheter was positioned in the right atrium for external stimulation. Dobutamine was given to increase cardiac output [2,3].…”

“…One of the most prominent early signs of cardiac decompensation is an increased pulmonary artery pressure (PAP). We are therefore developing the implantable sensor system COMPASS for remote monitoring of PAP, allowing physicians to timely adjust heart failure therapy and thereby prevent hospitalization [2][3][4]. The key element of the COMPASS system is a pressure sensor which is implanted in the pulmonary artery (Fig.…”