Pulmonary function derangements in isolated or predominant mitral stenosis — Preoperative evaluation with clinicohemodynamic correlation

Abstract

Introduction

It is well known that mitral stenosis (MS) is complicated by pulmonary hypertension (PH) of varying degrees. The hemodynamic derangement is associated with structural changes in the pulmonary vessels and parenchyma and also functional derangements. This article analyzes the pulmonary function derangements in 25 patients with isolated/predominant mitral stenosis of varying severity.

Aims

The aim of the study was to correlate the pulmonary function test (PFT) derangements (done by simple methods) with: a) patient demographics and clinical profile, b) severity of the mitral stenosis, and c) severity of pulmonary artery hypertension (PAH) and d) to evaluate its significance in preoperative assessment.

Subjects and Methods

This cross-sectional study was conducted in 25 patients with mitral stenosis who were selected for mitral valve (MV) surgery. The patients were evaluated for clinical class, echocardiographic severity of mitral stenosis and pulmonary hypertension, and with simple methods of assessment of pulmonary function with spirometry and blood gas analysis. The diagnosis and classification were made on standardized criteria. The associations and correlations of parameters, and the difference in groups of severity were analyzed statistically with Statistical Package for Social Sciences (SPSS), using nonparametric measures.

Results

The spirometric parameters showed significant correlation with increasing New York Heart Association (NYHA) functional class (FC): forced vital capacity (FVC, r = −0.4*, p = 0.04), forced expiratory volume in one second (FEV1, r = −0.5*, p = 0.01), FEV1/FVC ( r = −0.44*, p = 0.02), and with pulmonary venous congestion (PVC): FVC ( r = −0.41*, p = 0.04) and FEV1 ( r = −0.41*, p = 0.04). Cardiothoracic ratio (CTR) correlated only with FEV1 ( r = −0.461*, p = 0.02) and peripheral saturation of oxygen (SPO2, r = −0.401*, p = 0.04). There was no linear correlation to duration of symptoms, mitral valve orifice area, or pulmonary hypertension, except for MV gradient with PCO2 ( r = 0.594**, p = 0.002). The decreased oxygenation status correlated significantly with FC, CTR, PVC, and with deranged spirometry ( r = 0.495*, p = 0.02).

Conclusions

PFT derangements are seen in all grades of severity of MS and correlate well with the functional class, though no significant linear correlation with grades of severity of stenosis or pulmonary hypertension. Even the early or mild derangements in pulmonary function such as small airway obstruction in the less severe cases of normal or mild PH can be detected by simple and inexpensive methods when the conventional parameters are normal. The supplementary data from baseline arterial blood gas analysis is informative and relevant. This reclassified pulmonary function status might be prognostically predictive.