Tilt-induced changes in haemodynamic parameters in patients with cardiac resynchronisation therapy - a pilot study

Background: Cardiac resynchronisation therapy (CRT) has become a standard care in selected patients with advanced chronic heart failure (CHF). In order to achieve an adequate clinical response, CRT parameters have to be optimised following implantation. This procedure is usually performed on a patient in a supine position; however, measurement of haemodynamic parameters in an upright position may be clinically important. Aim: To compare haemodynamic parameters obtained in supine and erect positions in CRT patients undergoing optimisation procedures. Methods: The study group consisted of 10 consecutive patients (mean age 69.6+/-9 years, all males) who were scheduled for control outpatient CRT follow-up visits. Apart from routine device check-up, haemodynamic parameters [impedance cardiography (ICG) Task Force Monitor Systems, CNSystems, Austria] were measured. The ICG parameters were recorded during 20-min periods while supine and while tilted to 80 degrees. The last 30 cardiac cycles from each period were taken for further analysis. Parameters measured included heart rate (HR), systolic and diastolic blood pressure, stroke volume, cardiac output (CO) and total peripheral resistance (TPR). Results: Out of 60 measurements performed (6 parameters in 10 patients) all but nine differed significantly when comparing supine and erect positions. There was no uniform pattern regarding these changes. For example, HR increased after tilting in five patients, did not change in four, and slowed down in one patient. The changes in CO were significant in all but two patients, reaching a 50% increase in one patient. An abnormal response of TPR (significant decrease) was observed in 5 patients. There was no apparent association between tilt-induced changes in haemodynamic parameters and clinical response to CRT, whereas a significant negative correlation between tilt-induced changes in CO and left ventricular ejection fraction was found (r=-0.7, p<0.025). Conclusions: Tilting causes significant and often abnormal changes in haemodynamic parameters in CRT patients. The clinical significance of these findings needs further evaluation.