Right ventricular dysfunction during coronary artery occlusion: pressure-volume analysis using conductance catheters during coronary angioplasty

Abstract

Objective: To study the effects of coronary artery occlusion on the pressure-volume relations of the right ventricle.

Design: Right ventricular pressure-volume cycles were studied using conductance catheters and micromanometers in 19 subjects undergoing coronary angioplasty in a tertiary referral cardiac centre.

Results: Catheter occlusions of either the left anterior descending coronary artery or the right coronary artery were associated with a decline in stroke work (mean change (SD): left-13.3 (15.8)%, p = 0.008; right -13.5(16.5)%, p = 0.04). Two patterns of change were evident: an upward shift usually associated with occlusion in the left coronary artery, and a rightward shift in the right coronary artery. In the former there was an increase in maximum ventricular volume (mean change: 3.0(2.7)%, p = 0.004) and in minimum ventricular volume (mean change: 2.3(2.7)%, p = 0.01) and a fall in peak pressure (mean change: -4.8 (5.1)%, p = 0.04). In the latter there was an increase in peak pressure (mean change 9.9(16.3)%, p = 0.04) and an increase in minimum ventricular volume (mean change 3.7(5.0)%, p = 0.02) leading to a fall in stroke volume (mean change -13.3(15.8)%, p = 0.008).

Conclusions: Occlusion of the left anterior descending coronary artery or the right coronary artery is associated with a decline in right ventricular work. However, different patterns of change in indices of preload and afterload lead to different effects on overall right ventricular pump function.

Figure 1

Values of maximum right ventricular pressure (maxP) and conductance derived stroke volume (sv) in subjects undergoing coronary angioplasty. Values are displayed before balloon inflation (1), after 60 seconds of inflation (2), and 60 seconds after balloon deflation (3). Data from right coronary artery inflations are shown on the left and from left anterior descending coronary artery inflations on the right.

Figure 2

Right ventricular pressure-volume cycles from patients undergoing coronary angioplasty to lesions in the right coronary artery (above) and left anterior descending coronary artery (below). Two characteristic patterns of shift are contrasted with predominant rightward or vertical displacement. Vertical displacement is associated with a reduction in stroke volume, which in this subject results from a predominant reduction in maximum ventricular volume, while stroke volume during right ward displacement is maintained.

Figure 3

Right ventricular pressure-volume cycles from patients undergoing coronary angioplasty to lesions in the right coronary artery (above) and left anterior descending coronary artery (below). Two characteristic patterns of change in the diastolic pressure-volume relations are contrasted. The cycles in the top figure follow a continuous relation, and those in the bottom figure are displaced vertically during coronary artery occlusion.