P.068 A Non-Invasive Approach to Quantify Ventricular-Arterial Interaction: Comparing Vascular Type Ehlers-Danlos Syndrome Patients and Normal Individuals

Abstract

Introduction

We hypothesized that the pressure rate ratio (PRR), defined as the arterial upstroke dP/dt normalized by isovolumic ventricular dP/dt, is less sensitive to inter-subject variance and therefore better in identifying individuals with abnormal ventricular-arterial function than single hemodynamic parameters.

Methods

We studied the characteristics of PRR in 21 normals (age-range 19–32 yrs) and 7 age-matched vascular type (IV) Ehlers-Danlos syndrome (EDS) patients. ECG, brachial pressure and right common carotid artery (CCA) diameter waveforms (M-mode ultrasound) were obtained in supine position. LV systolic time intervals, i.e. isovolumic-contraction (ICP) and ejection periods (EP), were extracted from diameter waveforms using a previously described algorithm. We calculated diastolic blood pressure-to-ICP ratio (DBP/ICP), ICP/ EP, CCA-distension (ΔD), diastolic diameter (Dd), maximum diameter velocity (dD/dt,max), and distensibility (DC) and compliance (CC) coefficients. PRR was defined as 100%(K•dD/dt,max)/(DBP/ICP), with K = (mean blood pressure – DBP)/(mean diameter – Dd). Results are given as mean ± SD.

Results

EDS subjects had higher heart rate (+9bpm, p = 0.045), but lower ΔD (0.62 ± 0.11 vs 0.74 ± 0.15mm, p = 0.027) and DC (33 ± 8 vs 41 ± 9/MPa, p = 0.055). All other variables, including PRR (26 ± 7 vs 27 ± 6%), were not significantly different between groups, reflecting similar ventricular-arterial interaction. With both groups pooled, two individuals presented with elevated PRR (40%). In a normal subject (age 20 yrs) this was associated with abnormally low sympathetic activity. The other subject (EDS, age 24 yrs) exhibited increased sympathetic activity and decreased DC (20/MPa), shorter EP (−10%) and depressed LV function.

Conclusions

Our findings suggest that PRR enables identification of individuals with abnormal ventricular-arterial function in a heterogeneous population.