Relation between severity of mitral valve disease and results of routine lung function tests in non-smokers

Predictive nomogram for 28-day mortality risk in mitral valve disorder patients in the intensive care unit: A comprehensive assessment from the MIMIC-III database

BACKGROUND

Mitral valve disorder (MVD) stands as the most prevalent valvular heart disease. Presently, a comprehensive clinical index to predict mortality in MVD remains elusive. The aim of our study is to construct and assess a nomogram for predicting the 28-day mortality risk of MVD patients.

METHODS

Patients diagnosed with MVD were identified via ICD-9 code from the MIMIC-III database. Independent risk factors were identified utilizing the LASSO method and multivariate logistic regression to construct a nomogram model aimed at predicting the 28-day mortality risk. The nomogram's performance was assessed through various metrics including the area under the curve (AUC), calibration curves, Hosmer-Lemeshow test, integrated discriminant improvement (IDI), net reclassification improvement (NRI), and decision curve analysis (DCA).

RESULTS

The study encompassed a total of 2771 patients diagnosed with MVD. Logistic regression analysis identified several independent risk factors: age, anion gap, creatinine, glucose, blood urea nitrogen level (BUN), urine output, systolic blood pressure (SBP), respiratory rate, saturation of peripheral oxygen (SpO2), Glasgow Coma Scale score (GCS), and metastatic cancer. These factors were found to independently influence the 28-day mortality risk among patients with MVD. The calibration curve demonstrated adequate calibration of the nomogram. Furthermore, the nomogram exhibited favorable discrimination in both the training and validation cohorts. The calculations of IDI, NRI, and DCA analyses demonstrate that the nomogram model provides a greater net benefit compared to the Simplified Acute Physiology Score II (SAPSII), Acute Physiology Score III (APSIII), and Sequential Organ Failure Assessment (SOFA) scoring systems.

CONCLUSION

This study successfully identified independent risk factors for 28-day mortality in patients with MVD. Additionally, a nomogram model was developed to predict mortality, offering potential assistance in enhancing the prognosis for MVD patients. It's helpful in persuading patients to receive early interventional catheterization treatment, for example, transcatheter mitral valve replacement (TMVR), transcatheter mitral valve implantation (TMVI).

Comparison of the Results of Cardiopulmonary Exercise Testing between Healthy Peers and Pediatric Patients with Different Echocardiographic Severity of Mitral Valve Prolapse

Patients with mitral valve prolapse (MVP) have been reported to have exercise intolerance. However, the underlying pathophysiological mechanisms and their physical fitness remain unclear. We aimed to determine the exercise capacity of patients with MVP through the cardiopulmonary exercise test (CPET). We retrospectively collected the data of 45 patients with a diagnosis of MVP. Their CPET and echocardiogram results were compared with 76 healthy individuals as primary outcomes. No significant differences regarding the patient's baseline characteristics and echocardiographic data were found between the two groups, except for the lower body mass index (BMI) of the MVP group. Patients in the MVP group demonstrated a similar peak metabolic equivalent (MET), but a significantly lower peak rate pressure product (PRPP) (p = 0.048). Patients with MVP possessed similar exercise capacity to healthy individuals. The reduced PRPP may indicate compromised coronary perfusion and subtle left ventricular function impairment.

Pulmonary function derangements in isolated or predominant mitral stenosis - Preoperative evaluation with clinico-hemodynamic correlation

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.

Gas exchange consequences of left heart failure

This review explores the pathophysiology of gas exchange abnormalities arising consequent to either acute or chronic elevation of pulmonary venous pressures. The initial experimental studies of acute pulmonary edema outlined the sequence of events from lymphatic congestion with edema fluid to frank alveolar flooding and its resultant hypoxemia. Clinical studies of acute heart failure (HF) suggested that hypoxemia was associated only with the final stage of alveolar flooding. However, in patients with chronic heart failure and normal oxygenation, hypoxemia could be produced by the administration of potent pulmonary vasodilators, suggesting that hypoxic pulmonary vasoconstriction is an important reflex for these patients. Patients with chronic left HF commonly manifest a reduced diffusing capacity, an abnormality that appears to be a consequence of chronic elevation of left atrial pressure. That reduction in diffusing capacity does not appear to be primarily attributable to increases in lung water but is improved by any sustained treatment that improves overall cardiac function. Patients with heart failure may also manifest an abnormally elevated VE/VCO2 during exercise, and that exercise ventilation abnormality arises as a consequence of both alveolar hyperventilation and elevated physiologic dead space. That elevated exercise VE/VCO2 in an HF patient has proven to be a powerful predictor of an adverse outcome and hence it has received sustained attention in the HF literature. At least three of the classes of drugs used to treat HF will normalize the exercise VE/VCO2, suggesting that the excessive ventilation response may be linked to elevated sympathetic activity.

Heart failure and the lung

Heart failure (HF) is a highly prevalent disease that leads to significant morbidity and mortality. There is increasing evidence that the symptoms of HF are exacerbated by its deleterious effects on lung function. HF appears to cause airway obstruction acutely and leads to impaired gas diffusing capacity and pulmonary hypertension in the longer term. It is postulated that this is the result of recurrent episodes of elevated pulmonary capillary pressure leading to pulmonary oedema and pulmonary capillary stress fracture, which produces lung fibrosis. It is likely that impaired lung function impairs the functional status of HF patients and makes them more prone to central sleep apnoea.

The pulmonary manifestations of left heart failure

Determining whether a patient's symptoms are the result of heart or lung disease requires an understanding of the influence of pulmonary venous hypertension on lung function. Herein, we describe the effects of acute and chronic elevations of pulmonary venous pressure on the mechanical and gas-exchanging properties of the lung. The mechanisms responsible for various symptoms of congestive heart failure are described, and the significance of sleep-disordered breathing in patients with heart disease is considered. While the initial clinical evaluation of patients with dyspnea is imprecise, measurement of B-type natriuretic peptide levels may prove useful in this setting.

Alteration of the alveolar-capillary membrane diffusing capacity in chronic left heart disease

During left heart disease, the chronic increase in pulmonary capillary wedge pressure (PCWP) results both in vascular alterations with increased pulmonary vascular resistance (PVR), and in progressive thickening of the alveolar-capillary membrane, which diffusing capacity (Dm) is reduced. However, the total lung diffusing capacity for carbon monoxide (TLco) is inconstantly impaired, depending on the degree of pulmonary congestion. We evaluated the relation between the pulmonary hemodynamic repercussions of chronic heart disease and the 2 components of TLco, i.e., Dm and capillary blood volume. Forty-seven patients with chronic left heart disease (28 with valve disease, 19 with cardiomyopathy) underwent right heart catheterization with determination of PCWP and PVR. Pulmonary function tests, including spirometry, determination of TLco, and of its 2 components (percentage of predicted values) were performed in patients and in 15 healthy subjects. TLco and Dm, but not capillary blood volume, were significantly decreased in patients. Dm was related to PVR (p = 0.0006), and was markedly reduced in patients with high PVR (> or = 3 Wood U): 54 +/- 8% vs 80 +/- 19% in patients with normal PVR (p <0.0001). Dm < or = 66% identified all high PVR patients (sensitivity = 100%, specificity = 77%). Capillary blood volume was related to PCWP (p = 0.02), and was increased in patients with high PCWP (> 15 mm Hg): 126 +/- 30% vs 99 +/- 23% (p <0.01), but with a marked overlap. TLco values, although reduced in patients with high PVR (p <0.001), were not predictive of high PVR or high PCWP. Determination of Dm allows a more accurate detection of pulmonary hypertension complicating chronic left heart disease than the other pulmonary parameters.

The time course of pulmonary transfer factor changes following heart transplantation

OBJECTIVE

The pulmonary transfer factor for carbon monoxide (TLCO) has been reported to decline following heart transplantation, but the time course of this decline is not well documented. The aim of this study was to define the longitudinal changes in TLCO after heart transplantation.

METHODS

Single breath TLCO, lung volumes and expiratory flow rates were prospectively measured in 57 patients (mean age 49 years, range 19-61) before and at least once after heart transplantation. Thirty seven of the 57 patients had four post-transplant assessment which were performed at 6 weeks, 3, 6 and 12 months in 26 patients and at 12, 18, 24 and 36 months in 11 patients. Results were compared with data from 28 normal subjects (mean age 40 years, range 19-61).

RESULTS

Before transplantation there was a mild impairment of lung volumes and expiratory flow rates. At 6 weeks after transplantation, there was a further reduction in the forced expiratory volume in one second, forced vital capacity, residual volume and total lung capacity, but all of these increased in the subsequent measurements to exceed their pre-transplant values at about 1 year after transplantation. Haemoglobin-corrected TLCO was also reduced before transplantation compared to normal controls (74.3% and 98.6% of predicted respectively, P < 0.001). Although TLCO per unit alveolar volume (KCO) was relatively preserved in heart transplant candidates, it was still significantly lower than that of normal controls (92.6% and 105.3% of predicted respectively, P < 0.05). After transplantation, mean haemoglobin-corrected TLCO and KCO declined by 12% and 20% of predicted respectively) with the majority of patients having reductions greater than 10% of predicted. The decline in TLCO and KCO was evident at 6 weeks after transplantation with no further changes in the subsequent measurements.

CONCLUSIONS

TLCO is reduced in heart transplant candidates and declines further after heart transplantation despite improvement in lung volumes and airway function. The early and non-progressive nature of TLCO decline suggests an aetiology exerting its effect on TLCO within the first 6 weeks after transplantation.

Can an echocardiographic score predict who will benefit clinically from balloon dilation of the mitral valve?

Deciding whether a patient with sub-optimal mitral valve anatomy will benefit from percutaneous mitral valvotomy remains a demanding clinical problem. We assessed the ability of an established echo score applied to transoesophageal images to predict absolute increases in mitral valve area and improvement in exercise capacity. Twenty five consecutive patients undergoing routine percutaneous mitral valvotomy were studied. Changes in exercise tolerance were measured by serial cardiorespiratory treadmill exercise testing. Before the procedure, exercise duration was directly related to mitral valve area (rs = 0.44, P < 0.05). Following percutaneous mitral valvotomy there was an increase in valve area (0.9 +/- 0.2 to 1.4 +/- 0.3 cm2, P < 0.0001) and repeat exercise testing demonstrated increases in exercise duration (470 +/- 220 to 610 +/- 240 s, P < 0.001) and peak VO2 (12.6 +/- 4.2 to 15.1 +/- 4.5 ml/kg/min, P < 0.01). There was an inverse correlation between the echo score and the increase in valve area (rs = -0.52, P < 0.05) but no relationship between the echo score and the increase in exercise duration or peak minute oxygen consumption (VO2). These data demonstrate that a score applied to transoesophageal images echocardiographic images can predict changes in mitral valve area but that the score fails to predict functional improvement for an individual patient. This suggests, therefore, that patients without contraindications to valvotomy whose valves have a high echo score should still be considered for valvotomy as they may benefit considerably from the procedure.

Reduced alveolar-capillary membrane diffusing capacity in chronic heart failure. Its pathophysiological relevance and relationship to exercise performance

BACKGROUND

The pulmonary diffusing capacity for carbon monoxide (DLCO) is reduced in chronic heart failure (CHF) and is an independent predictor of peak exercise oxygen uptake. The pathophysiological basis for this remains unknown. The aim of this study was to partition DLCO into its membrane conductance (DM) and capillary blood volume components (Vc) and to assess if alveolar-capillary membrane function correlated with functional status, exercise capacity, and pulmonary vascular resistance.

METHODS AND RESULTS

The classic Roughton and Forster method of measuring single-breath DLCO at varying alveolar oxygen concentrations was used to determine DM and Vc in 15 normal subjects and 50 patients with CHF. All performed symptom-limited maximal bicycle exercise tests with respiratory gas analysis; 15 CHF patients underwent right heart catheterization. DLCO was significantly reduced in CHF patients compared with normal subjects, predominantly because of a reduction in DM (7.0 +/- 2.6 versus 12.9 +/- 3.8 versus 20.0 +/- 6.1 mmol.min-1.kPa-1 in New York Heart Association class III, class II, and normal subjects, respectively, P < .0001), even when the reduction in lung volumes was accounted for by the division of DM by the effective alveolar volume. The Vc component of DLCO was not impaired. DM significantly correlated with maximal exercise oxygen uptake (r = .72, P < .0001) and inversely correlated with pulmonary vascular resistance (r = .65, P < .01) in CHF.

CONCLUSIONS

Reduced alveolar-capillary membrane diffusing capacity is the major component of impaired pulmonary gas transfer in CHF, correlating with maximal exercise capacity and functional status. DM may be a useful marker for the alveolar-capillary barrier damage induced by raised pulmonary capillary pressure.

Increased alveolar/capillary membrane resistance to gas transfer in patients with chronic heart failure

OBJECTIVE

To investigate pulmonary diffusive resistance to gas exchange in patients with heart failure and healthy volunteers, assessing the relative contributions of the alveolar/capillary membrane and pulmonary capillary blood.

SETTING

Hospital outpatient department and pulmonary function laboratory.

PATIENTS

38 patients (mean age 60) receiving treatment with loop diuretics and angiotensin converting enzyme inhibitors for stable symptomatic heart failure of > 6 months duration (New York Heart Association (NYHA) classes II and III). Results were compared with those of 17 healthy volunteers (mean age 52).

METHODS

The alveolar/capillary membrane diffusive resistance and the pulmonary capillary blood volume available for physiological gas exchange were determined by the Roughton and Forster method, which measures the single breath pulmonary diffusing capacity for carbon monoxide at varying alveolar oxygen concentrations.

RESULTS

Total pulmonary diffusive resistance was higher in patients than controls. Alveolar/capillary membrane resistance formed the main component of this increase, accounting for a mean (SD) of 63% (20%) and 86% (8%) of total pulmonary diffusive resistance in patients in NYHA II and III classes respectively, compared with 53% (10%) in controls. The pulmonary capillary blood volume was not significantly different between controls and patients in NYHA class II (66 (18) ml v 61 (18) ml), but was increased in those in NYHA class III (95(46) ml, P < 0.05).

CONCLUSION

This study confirmed impairment of pulmonary diffusion at rest in patients with chronic heart failure and identified impaired alveolar/capillary membrane function as the main factor responsible.

Bronchial hyperreactivity in patients with mitral valve disease

To elicit the mechanism of bronchial hyperreactivity (BHR) in chronic heart failure (CHF), a methacholine inhalation test, pulmonary function test, and cardiac catheterization were performed in 19 patients with mitral valve disease (MVD), and the change of severity of BHR before and after mitral valve replacement (MVR) was also examined in seven of 19 patients with MVD. Sixteen of 19 patients with MVD showed significant increase in respiratory resistance in methacholine inhalation test, while all normal subjects did not. The maximal expiratory flow at 25 percent of vital capacity (Vmax25), a parameter of small airway disease, correlated significantly with log cumulative dose producing a 35 percent decrease in respiratory conductance (PD35Grs) (r = 0.536) and the duration of symptoms (r = -0.682). There was a significant correlation between log PD35Grs and mean pulmonary artery wedge pressure (r = -0.466). After MVR, log PD35Grs was significantly improved in all seven operated-on patients, although six patients retained BHR. We conclude that patients with long-term MVD have marked BHR and that BHR in long-term MVD is related to peripheral airway narrowing with organic remodeling, which was not ameliorated with MVR procedure, in addition to pulmonary congestion.

Heart failure and airway obstruction

We investigated 60 patients with severe left-sided heart failure before and after cardiac recompensation. We observed that the cardiac insufficiency had a marked effect on dynamic ventilatory parameters. The "effort independent part" of the flow-volume curve was changed significantly by means of cardiac therapy.

Effects of valvular surgery on overall and regional lung function in patients with mitral stenosis

Changes in overall and regional pulmonary function after open heart surgery were studied in 23 patients with mitral stenosis, grouped according to hemodynamic abnormality at cardiac catheterization. In group 1 (pulmonary arterial pressure less than 25 mm Hg), no pulmonary function disorders were detected before or after surgery. In group 2 (pulmonary hypertension with no or slight tricuspid regurgitation) lung volumes increased significantly within normal ranges after surgery. However, group 3 patients (pulmonary hypertension and moderate or severe tricuspid regurgitation, restrictive and obstructive impairment, uneven alveolar ventilation, disturbed diffusing capacity) did not recover after surgery. The regional perfusion distribution by 133Xe, expressed as the upper over lower lung field ratio, showed significant changes after surgery in groups 1 and 2, but no change in group 3. In groups 1 and 2 it seems that lung parenchyma and pulmonary vessels were not greatly damaged, while in group 3 organic changes in the lung occurred.

Effects of mitral valve surgery on static lung function and exercise performance

Lung function at rest was assessed in 50 patients before and six months after mitral valve surgery. There were small increases in spirometric volumes (FEV1 and vital capacity) with decreases in total lung capacity and residual volume, but no change in carbon monoxide transfer factor or transfer coefficient (KCO). Progressive exercise tests performed before and after operation in 19 of the patients confirmed an improved exercise capacity after surgery. The patients with the greatest symptomatic improvement in breathlessness were also those who achieved the greatest increase in maximum work load and the greatest decrease in ventilation for a given oxygen consumption. Depression of the ST segment of the electrocardiogram and frequent ventricular ectopic beats on exercise remained common after surgery and may have been due to digoxin treatment.