Assessment of left ventricular end-systolic pressure-volume relations with an impedance catheter and transient inferior vena cava occlusion: Use of this system in the evaluation of the cardiotonic effects of dobutamine, milrinone, posicor and epinephrine

Abstract

The end-systolic pressure-volume relation has been postulated as a load-independent measure of cardiac contractility, but has been difficult to measure because of technical problems associated with the serial measurement of intracardiac volume over a physiologic range of ventricular loading conditions. Utilizing a multielectrode impedance catheter to assess continuous, on-line left ventricular relative volume during transient inferior vena cava occlusion, a method is described for determining the end-systolic pressure-volume relation and for assessing changes in this relation secondary to inotropic modulation. In particular, using this method, the relative inotropic properties were determined of four drugs: dobutamine, milrinone, epinephrine and an experimental cardiotonic agent (Ro 13-6438, Posicor). Left ventricular micromanometer pressure and impedance catheter volume were measured continuously in 10 open chest, anesthetized dogs and 14 pigs. Arterial pressure was altered over a range of 20 to 60 mm Hg by brief inferior vena cava constriction. A linear end-systolic pressure-volume relation was observed in pressure-volume diagrams constructed from on-line pressure and impedance catheter recordings. Administration of dobutamine, milrinone and epinephrine resulted in a leftward shift and an increase in the slope of the end-systolic pressure-volume relation as compared with baseline; Posicor did not alter the slope over a range of doses, despite an increase in the cardiac output secondary to arterial vasodilation. Volume changes as measured by the impedance method closely paralleled simultaneous changes in the ultrasonic crystal-determined segment length, and the impedance end-systolic pressure-volume relation slope was reproducible with repeated load-altering maneuvers.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of the new class I antiarrhythmic agent diprafenone on the end-systolic pressure-volume relationship (conductance technique)

“…It offers the possibility of producing any number of beat-to-beat pressure-volume diagrams over a wide range of load changes; all this is achieved in connection with the technique of rapid load changes with temporary balloon occlusion in the inferior vena cava. Investigations using this combined technique are experimentally sound, have been brought to maturity [13,35], and have proven their reliability and practicability in our catheterization laboratory for 3 years [8][9][10][11][12]14]. This method specifically lends itself to the assessment of contractile reserves in different cardiac diseases [22][23][24], as well as to the analysis of the complex hemodynamic effects of new cardiotonic drugs [12].…”

“…However, the data are inadequate to make a definitive statement regarding the effects of proprafenone on myocardial contractility. There are reports of hypotension and a moderate negative inotropic action [30][31][32][33][34][35][36][37][38][39][40].…”

“…Thus the conductance system has now been cleared of the stigma of inaccurate volume measurements due to the "parallel conductance" problem [20,21]. It has now been accepted that the system's continuous signal for volume measurements is proportional to the actual chamber volume [7,35].…”

Proof for piroximone's inotropic influence: Can it safely be used in coronary artery disease? analysis of end-systolic pressure-volume relations (conductance technique)

“…For the required construction of the line of the isometric maxima, we used the temporary balloon occlusion (Fig. 1, bottom) in the vena cava inferior [7,[24][25][26], as multiple loops under different loading conditions are required for correct measurements. The ESPVR loop motion of the initial cycles as induced by the sudden and temporary preload changes via balloon occlusion determines the course of the isometric maxima line (the ESPVR) for the respective interventional condition.…”

Left ventricular volume determination in dogs: a comparison between conductance technique and angiocardiography

“…Under ideal conditions, if the tissues were a perfect insulator, all the measuring current would pass only through the left ventricular cavity, and extremely accurate volume measurements could be obtained' 14 '. The electrical impedance of the myocardium is approximately 100-fold greater than that of blood' 15 ' and, therefore, tends to contain the current within the left ventricle and to render changes in conductivity of the right ventricle small in comparison with changes in left ventricular conductivity. However, changes in left atrial volume can affect conductance measurements in an important way, because no insulating wall exists between the left atrium and left ventricle.…”