Effects of Negative Pleural Pressure on Left Ventricular Hemodynamics SHELDON A. MAGDER, MD, SAMUEL LICHTENSTEIN, MD, PhD,and ALLAN G. ADELMAN,MD Negative pleural pressure alters left ventricular (LV) function. LV volume changes have been studied in human subjects, but little is known of the hemody- namic effects. The effect of changes of pleural pressure on LV hemodynamics during a Mueller maneuver (inspiration against an obstruction) was studied in 11 subjects and during quiet, unobstructed inspiration in 3. During the Mueller maneuver, there was an initial decrease in pulmonary wedge pres- sure and aortic systolic pressure, almost as great as the .decrease in pleural pressure. Thereafter, these pressures increased despite a sustained reduction in pleural pressure. Toward the end of the Mueller maneuver, pulmonary wedge transmural pressure averaged 31 f 12 mm Hg and in 6 patients large Y waves developed. The increase in aortic transmural pressure averaged 30 f 16 mm Hg. Aortic pulse Fluid accumulation in the lungs is enhanced by very negative pleural pressuresi and negative pleural pres- sures are frequently seen in conditions with airway obstruction2 as well as conditions with noncompliant lungs such as pulmonary edema.3 The potential mech- anism for this fluid accumulation has become clearer in the past few years. Negative pleural pressure affects left ventricular (LV) function by at least 2 mechanisms: It causes an increase in the venous return to the right side of the heart,4 which results in increased right ventricular (RV) volume, a shift in the ventricular septum to the left,5 and kV interference with LV function.6-11 It also produces an impedance to LV ejection.g-15 Both of these mechanisms lead to an increase in left atria1 LA transmural pressure (that is, LA pressure relative to pleural pressure). This increases the pulmonary venous and capillary hydrostatic pressures, which, in turn, leads to greater fluid accumulation in the lungs.1+2 The effects From the Department of Medicine, Toronto General Hospital, Toronto, Ontario Canada. This study was supported, in part, by The Canadian Heart Foundation, Ottawa, Ontario. Manuscript received August 12, 1983; revised manuscript received May 23, 1983, accepted May 24, 1983. Address for reprints: Sheldon Magder, MD, Cardiology Division, Royal Victoria Hospital, 687 Pine Avenue West, Montreal H3A 1A 1, Quebec, Canada. pressure decreased on the first beat from control levels of 59 f 21 to 47 f 21 (p <O.OOl) and then returned to control levels. During normal breathing in 3 subjects, studied with intraesophageal balloons, there was a similar increase in both transmural aortic and transmural pulmonary wedge pressures’ zyxwvutsrqponmlkjihgfedcba with a decrease in pleural pressure 6 mm Hg during inspiration. Thus, increased negative pleural pressure was associated with a marked increase in pulmonary wedge transmural pressure; the increase was ap- proximately proportionate to the decrease in pleural pressure. It is suggested that this increase was due to increased impedance to LV ejection and to right ventricular expansion interfering with LV diastolic filling. ; (Am J Cardiol 1963;52:566-593) of a negative pleural pressure on LV volumes has been well studied,14Js but few data are available on the ventricular pressure changes in human subjects16 This study quantitates the increase in LA and aortic transmural pressure during an inspiratory effort to determine the potential magnitude of the hemodynamic effects of negative pleural pressure in human subjects. Methods The effects of the Mueller maneuver were observed in 7 men and 4 women, aged 39 to 66 years, during routine cardiac catheterization. Seven patients had coronary artery disease, 3 valvular disease and 1 dilated cardiomyopathy. The details of their hemodynamic findings are given in Table I. LA pressure was estimated from pulmonary wedge pressure de- termined by an end-hole 7Fr catheter inserted percutaneously into the femoral vein and advanced to the pulmonary wedge position. The PW was compared with the LV end-diastolic pressure determined by a retrograde arterial catheterization. Changes in mouth pressure were used to estimate changes in pleural pressure. In a Mueller maneuver, there is no air flow; therefore, changes in mouth pressure closely reflect changes in alveolar pressure, which in turn reflect changes in pleural pressure.io A pressure manometer allowed the patient to see the extent of the pressure change. All pressures were measured with Statham strain-gauge transducers placed 5 cm above the table level.