Effect of closed mitral valvotomy on spirometric pulmonary function tests in mitral stenosis.
PP Kadam, SH Pantvaidya, SR Jagtap, KD Rajgor
Department of Anaesthesiology, LTMM College, Sion, Mumbai.
P P Kadam
Department of Anaesthesiology, LTMM College, Sion, Mumbai.
The effect of closed mitral valvotomy on the spirometric pulmonary functions was studied in 25 patients with mitral stenosis. The tests were performed before and after operation, the latter at varying intervals (4 to 6 weeks and 8 to 12 months). The preoperative values were considerably low. After 4 to 6 weeks following surgery, further significant reduction in Forced Vital Capacity (FVC) and Forced Expiratory Volume in one second (FEV1) was observed. This was ascribed to the residual healing process and thoracotomy pain. However, Forced expiratory flow rate during mid segment of FVC (FEF25-75%), which reflects obstruction in small airways, did not show any variation. There was improvement in all the above parameters, 8-12 months after surgery. This suggests definite reversibility in the pulmonary functions following valvotomy.
|How to cite this article:|
Kadam P P, Pantvaidya S H, Jagtap S R, Rajgor K D. Effect of closed mitral valvotomy on spirometric pulmonary function tests in mitral stenosis. J Postgrad Med 1997;43:38-40
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Kadam P P, Pantvaidya S H, Jagtap S R, Rajgor K D. Effect of closed mitral valvotomy on spirometric pulmonary function tests in mitral stenosis. J Postgrad Med [serial online] 1997 [cited 2020 May 28 ];43:38-40
Available from: http://www.jpgmonline.com/text.asp?1997/43/2/38/412
Mitral valve stenosis produces well recognised abnormalities in the lung functions,,. In this disease the pathophysiological changes in the pulmonary vasculature and parenchyma cause reduction in compliance and vital capacity, and increase in airway resistance. The bronchial congestion adds to the ventilatory insufficiency with susceptibility to infection.
Rhodes et al have demonstrated improvement in Forced vital capacity (FVC) and Forced expiratory volume in one second (FEV1) 6 months after Mitral valve surgery. However data obtained by Singh et al following Mitral valvotomy showed reduction after 3 to 5 months and was not significantly different from preoperative value, even at 6 to 11 months and 12 to 24 months following surgery.
Since the results with regards to improvement in pulmonary functions have been contradictory we carried out prospective study in 25 patients with Mitral stenosis to know the effect of closed mitral valvotomy on the spirometric pulmonary function tests at varying intervals.
Twenty five adult patients with mitral stenosis scheduled for closed mitral valvotomy were studied. There were 15 females and 10 males, weighing 40.28+7.49 kg. They were graded according to NYHA classification. None of the patients had primary pulmonary disease.
The Forced vital capacity (FVC), Forced expiratory volume in one second (FEV1), Forced expiratory flow rate during midsegment of FVC (FEF25-75%) and FEV1/FVC ratio were determined. All measurements except FEV1/FVC, were recorded as percentage of the predicted values according to oriental norms. The spirometric tests and clinical assessment were done before surgery and repeated at 4-6 weeks and 8-12 months postoperatively.
The patients were considered high risk for anaesthesia and surgery if one of FVC, FEV1, FEF25-75% was less than 50% of the predicted or FEV1/FVC ratio was less than 70%., The postoperative respiratory complications if any were noted and treated.
The data was subjected to statistical analysis.
The percentage predicted values of FVC, FEV1, FEF25-75% and FEV1/FVC ratio were low preoperatively [Table:1] and [Table:2]. Four to six weeks after operation, though the patients showed clinical improvement [Table:3], there was further statistically significant reduction in FVC, FEV1 and hence FEV1/FVC. However there was no change in FEF25-75%. At the 8-12 months follow up there was improvement in all spirometric tests compared to the preoperative values [Table:1] and [Table:2], this correlated with clinical assessment.
Though majority of the patients (80%) were in high risk group as assessed by FEF25-75% before operation [Table:4], none of the patients required ventilatory support postoperatively. Only one patient had a right upper lobe radiological opacity without any clinical manifestation of pneumonia. This resolved with chest physiotherapy and antibiotics.
Various authors have demonstrated that there is a reduction in FVC and FEV1 of the patients with mitral valve disease,,. Similar data was obtained from our study. Studies have shown that the pulmonary vascular congestion and interstitial peribronchial oedema, in response to the elevation of left atrial pressure, cause increase in distal airway resistance to a greater extent than that in total airway resistance. Our findings corroborated this. The FEF25-75%, being a sensitive index of peripheral airway obstruction, was markedly low compared to FEV1, in our patients preoperatively.
Singh et al observed further reduction in FVC (0.35+0.12 litre) at 3 to 5 months after mitral valvotomy. Similarly we found decrease in FVC and FEV1, by 26.43% and 18.76% respectively, 4-6 weeks after operation. This has been attributed to the thoracotomy itself, with its associated pain and restrictive effect,. FEF25-75% being effort independent did not show any variation. However most of our patients improved clinically as assessed by NYHA grading at this follow up.
Singh et al also studied pulmonary function in other two groups of patients 6-11 months and 12-24 months following mitral valvotomy, they noticed no alterations in lung volumes from those before operation. Whereas Rhodes et al demonstrated improvement in FVC and FEV1 6 months after mitral valve surgery. Our further follow up at 8-12 months showed rise in FVC, FEV1, FEV1/FVC and predominantly in FEF 25-75% by 18.74%, 34.45%, 15.67% and 72.04% respectively. This suggests that the pulmonary changes were reversing after valvotomy. Though on the basis of FEF25-75% most of our patients were considered high risk for surgery, none had any major postoperative respiratory complication.
It appears that FEF25-75% is a sensitive index of the pulmonary changes, in the patients with mitral stenosis. The pulmonary functions improved 8-12 months after valvotomy. Hence poor spirometric pulmonary functions (of the degree considered to be contraindication for pneumonectomies) should not deprive the patients of valvotomy in the fear of postoperative complications.
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