Lung Function in Cardiac Dysfunction

Abstract

The alterations in lung function caused by heart failure were first described some decades ago. The advent of new tools for the diagnosis and investigation of heart disease, such as echocardiography, has subsequently made it possible to classify cardiac dysfunction with greater precision. The objective of this study was to analyze and compare a series of lung function and gas exchange variables in patients who had been classified into 4 groups according to type of heart disease as diagnosed by echocardiography. Emergency room patients whose main symptom was acute dyspnea caused by cardiac or respiratory disease were included in the study. The final sample comprised 71 patients whose echocardiogram revealed cardiac dysfunction. Spirometry was carried out and resting arterial blood gases measured in this group. Of the 71 patients with cardiopathy, 31 had systolic dysfunction, 27 diastolic dysfunction, 7 cor pulmonale, and 6 primary valve disease. Spirometry revealed a generally obstructive pattern, more marked in the group with cor pulmonale. Analysis of arterial blood gases revealed slight hypoxemia with normocapnia in all groups, but this was more accentuated in the patients with cor pulmonale and diastolic dysfunction. An analysis of the correlations (Pearson's r) between cardiac and pulmonary variables revealed the statistically significant associations between cardiac mass and other variables to be as follows: forced vital capacity r=0.34 (P=.02), forced expiratory volume in one second r=0.526 (P=.0001), forced expiratory volume in one second as a percentage of predicted r=0.3 (P=.037), and forced midexpiratory flow rate r=0.31 (P=.03). The correlation between left ventricular ejection fraction and PaO2 was r=-0.312 (P=.01); the correlation between left ventricular end-diastolic diameter and PaO2 was r=0.369 (p=.006). In patients with cardiac dysfunction, spirometry reveals a generally obstructive pattern, which is more accentuated in patients with right ventricular dysfunction owing to the existence of prior lung disease. The associations found between the cardiac and lung function variables do not help the physician to determine the predominant diagnosis for a patient more precisely or to establish a prognosis.