Reduction of mismatch of global ventilation and perfusion on exercise is related to exercise capacity in chronic heart failure.

Abstract

Background-The inability to match lung perfusion to ventilation because of a reduced cardiac output on exercise contributes to reduced exercise capacity in chronic heart failure.Objective-To quantify ventilation to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. Design-Eight men in New York Heart Association class II underwent maximal bicycle ergometry with i gas anasis. Main outcome measures-On separate days, ventilation and perfusion gamma camera imaging was performed at rest, and at 80% of previous peak exercise heart rate during bicycle ergometry. The vertical distribution of mismatch between ventilation and perfusion (V/Q) was estimated from subtracted profiles of activity (ventilation and perfusion) to derive a numerical index of global mismatch. Results-Maximal mean (SD) oxygen consumption on bicycle ergometry was 16-0 (4.5) ml min-' kg-'. There was a reduction in the global V/Q mismatch index from 23-96 (5.90) to 14-88 (7.90) units (p < 0.01) at rest and at peak exercise. Global V/Q mismatch index at peak exercise correlated negatively with maximal minute ventilation (R = -0 90, p < 0-01) and with maximal mean arterial pressure (R = -0 79, p < 0.05), although no relation was seen with maximal oxygen consumption. The reduction in global V/Q mismatch index from rest to peak exercise correlated with maximal oxygen consumption (R = 0-88, p < 0.01), and with maximal minute ventilation (R = 0-87, p < 0.01). Conclusions-During exercise in patients with chronic heart failure, there is a reduction in the global V/Q mismatch index. A lower global V/Q mismatch index at peak exercise is associated with higher maximal ventilation. The reduction in global VIQ mismatch index on exercise correlates weli with maximal exercise capacity. This may imply that the inability to perfuse adequately all regions of lung on exercise and match this to ventilation is a factor determiniing exercise capacity in chronic heart failure.(Br Heart J 1993;70:241-246)

Exercise Testing and Training in Children With Congenital Heart Disease

“…48 Patients with CHF have pulmonary blood flow maldistribution as a consequence of the elevated pulmonary capillary wedge pressure that accompanies CHF. 47,51 As ventricular function deteriorates and the wedge pressure rises, the pulmonary blood flow maldistribution (and consequent V/Q mismatch) worsens, and the V E/V CO 2 slope progressively rises. This strong link between pulmonary capillary wedge pressure and the V E/V CO 2 slope probably accounts for the prognostic power of the V E/ V CO 2 slope in this patient population.…”

Ventilatory Efficiency and the Selection of Patients for Heart Transplantation

“…41 On a pathophysiological level, an increased VE/VCO 2 slope has been associated with a number of abnormalities that underlie CHF, such as increased ventilation-perfusion mismatching 21,22 and an abnormally heightened chemosensitivity and ergoreflex response. [23][24][25] Previous studies have shown that the risk of events is continuous across a wide range of VE/VCO 2 slope values.…”

“…7,13 These limitations of peak VO 2 have prompted the search for new and better CPX prognostic parameters among which the most prominent is ventilatory efficiency assessed by the slope of minute ventilation (VE) versus carbon dioxide production (VCO 2 ). 6,16 -20 The rationale behind the use of ventilatory efficiency is that patients with CHF exhibit an excessive ventilatory response to exercise that is proportional to the degree of CHF severity, reflecting an increased ventilation-perfusion mismatch 21,22 and exaggerated chemosensitivity and ergoflex response. [23][24][25] The prognostic capabilities of VE/VCO 2 slope were demonstrated in several studies where it outperformed peak VO 2 , 6,16 -19,23,26 -31 but despite this apparent superiority, peak VO 2 continues to be the main CPX parameter used to guide listings for HTx.…”

The combined exercise stress echocardiography and cardiopulmonary exercise test for identification of masked heart failure with preserved ejection fraction in patients with hypertension

“…[27][28][29][30] However, this ventilatory limitation with dyspnoea is more exaggerated in patients with HFpEF, followed by intolerance due to increase of the PCWP.…”