Influence of Heart Rate and Epicardial Stenosis Severity on Cardiac Contractility Under Concomitant Microvascular Disease in a Porcine Model

Invasive guide wire methods to assess functional severity of coronary stenosis are affected by dynamic variables like heart rate (HR), contractility, epicardial stenosis (AS) and blood pressure. The interdependence of these factors is also influenced by the presence of concomitant microvascular disease (CMVD). The purpose of this study is to assess the variation in contractility under varying HR and AS in the presence of CMVD. In vivo experiments were performed on seven Yorkshire pigs. It was found that, in the presence of concomitant microvascular disease (CMVD), for lower AS (<50%) contractility increases for HR<120 bpm while it marginally decreases for HR>120 bpm. However, for higher AS (>50%), contractility decreases for both HR<120 bpm and HR>120 bpm.