Does Restrictive Lung Function Affect the Exercise Capacity in Patients with Repaired Tetralogy of Fallot?

Body plethysmography - additional information on exercise capacity in patients with congenital heart disease?

AIMS

In each cardiopulmonary exercise test (CPET), resting spirometry is performed in advance. In patients with a congenital heart defect (CHD), lung volumes are often impaired. This study investigates correlations between lung volumes and CPET parameters and determines, whether body plethysmography provides substantial additional information for these patients.

METHODS

Data from 102 patients (23.8 ± 10.4 years of age, 39 female) with various forms of CHD were examined from April 2018 to October 2022. All patients underwent spirometry (measuring forced vital capacity, FVC and forced expiratory volume in 1 s, FEV1), body plethysmography (measuring total lung capacity, TLC) and an exhausting CPET. Data is presented as the median and interquartile range (z-scores) and correlated with Spearman's rho.

RESULTS

Fifty-five% of all patients had normal results in lung function and 45% had normal peak oxygen uptake (≥ 80% predicted in peak VO2). Patients with impaired lung function were significantly more likely to have low exercise capacity (Fisher's exact test: p = 0.028). FVC z-values and %predicted peak VO2 (r = 0.365, p < 0.001) correlated significantly as well as FEV1_z and %predicted peak VO2 (r = 0.320, p = 0.001), and TLC z-values and %predicted peak VO2 (r = 0.249, p = 0.012). No correlation was found between FEV1/FVC z-values and %predicted peak VO2 (r = -0.043, p = 0.670).

CONCLUSION

Spirometry and exercise capacity positively correlate, also in CHD patients. However, body plethysmography does not provide additional or improved prediction and is therefore only recommended in noteworthy results in spirometry to exclude further lung co-morbidities.

Abnormalities in pulmonary function and volumes in patients with CHD: a systematic review

BACKGROUND

Lung function and cardiac function are naturally correlated by sharing the thoracic cage and handling the whole cardiac output sequentially. However, lung function studies are rare in patients with CHD, although results worthy of investigation could be expected. This review summarises existing studies with the lung function parameters (spirometry and body plethysmography) in CHD patients during the last decade.

METHODS

A systematic review was performed in the relevant database (PubMed, Cochrane, and Scopus) in studies including paediatric and adult patients with CHD where lung parameters (spirometry, body plethysmography) were investigated from January 2010 to December 2020. Two independent reviewers evaluated the studies according to the Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the National Heart, Lung, and Blood Institute.

RESULTS

Eight studies investigated patients with Fontan palliation including 704 patients (306 female). Four studies included patients after repaired tetralogy of Fallot examining 219 patients (103 female), with one study using double. Further six studies included 3208 (1324 female) children and adults with various CHDs. Overall, four studies were categorised as "good", ten as "fair", and four as "poor". While the measurements were consistently standardised, references to calculate %predicted differed substantially across all studies. All evaluated studies showed reduced forced vital capacity in the majority of CHD patients.

CONCLUSIONS

Many CHD patients have a reduced forced vital capacity independent of their underlying defect. Spirometry should not only follow a standardised measure according to ATS (update 2019) but also stick to the 2012 GLI reference values.

Exercise Capacity After Arterial Switch Operation in Patients with D-Transposition of Great Arteries: Does the Coronary Artery Anatomy Matter?

Variant coronary anatomy (VarCA) is frequent in D-Transposition of the great arteries (d-TGA). There are a paucity of data on the effect of the VarCA on the exercise capacity (XC) in patients with repaired d-TGA. This retrospective study included patients with d-TGA who underwent an arterial switch operation (ASO) and had at least one cardiopulmonary exercise test (CPET). Data from the treadmill CPET and simultaneously performed spirometry were collected. The parameters of CPET were compared between patients with usual anatomy vs. VarCA. Longitudinal changes in XC in patients with ASO were also analyzed. A total of 44 patients with either usual coronary anatomy (n = 27, 61%) or VarCA (n = 17, 39%) met inclusion criteria. There was no significant difference in oxygen consumption (%VO₂) at initial CPET (104 vs. 100%, p = 0.53) between the two groups. Abnormal %VO₂ (< 85%) was uncommon in both groups (n = 2, 7.4% vs. n = 4; 23.5%; p = ns). For longitudinal changes, there was no significant decline in %VO₂ in either group: (i) usual coronary anatomy (n = 15, median follow-up 4.8 years, %VO₂ 111 vs. 108%; p = 0.306) and (ii) VarCA (n = 10, median follow-up 6.6 years, %VO₂ 106 vs. 92%; p = 0.441). Spirometry was abnormal in 25 (59.5%) patients [restrictive (n = 8, 19.0%), obstructive (n = 15, 35.7%), and mixed (n = 2, 4.8%)] butabnormal spirometry had no impact on the XC. Patients with d-TGA who underwent neonatal ASO uniformly exhibited good XC without any longitudinal decline on medium-term follow-up, regardless of coronary artery anatomy. Although frequent (60%), abnormal spirometry was not associated with reduced exercise capacity.

Breathing training improves exercise capacity in patients with tetralogy of Fallot: a randomised trial

OBJECTIVE

Patients with tetralogy of Fallot (ToF) have limited pulmonary blood flow before corrective surgery and ongoing dysfunction of the pulmonary valve and right ventricle throughout life leading to lower exercise capacity and lung volumes in many patients. Inhalation training can increase lung volumes, improve pulmonary blood flow and consequently exercise capacity. This study tests whether home-based daily breathing training improves exercise capacity and lung volumes.

METHODS

From February 2017 to November 2018, 60 patients (14.7±4.8 years, 39% female) underwent spirometry (forced vital capacity (FVC); forced expiratory volume in 1 s (FEV1)), cardiopulmonary exercise testing (peak oxygen uptake (peak [Formula: see text]O2)) and breathing excursion measurement. They were randomised into immediate breathing exercise or control group (CG) and re-examined after 6 months. The CG started their training afterwards and were re-examined after further 6 months. Patients trained with an inspiratory volume-oriented breathing device and were encouraged to exercise daily. The primary endpoint of this study was the change in peak [Formula: see text]O2. Results are expressed as mean±SEM (multiple imputations).

RESULTS

In the first 6 months (intention to treat analysis), the training group showed a more favourable change in peak [Formula: see text]O2 (Δ0.5±0.6 vs -2.3±0.9 mL/min/kg, p=0.011), FVC (Δ0.18±0.03 vs 0.08±0.03 L, p=0.036) and FEV1 (Δ0.14±0.03 vs -0.00±0.04 L, p=0.007). Including the delayed training data from the CG (n=54), this change in peak [Formula: see text]O2 correlated with self-reported weekly training days (r=0.282, p=0.039).

CONCLUSIONS

Daily inspiratory volume-oriented breathing training increases dynamic lung volumes and slows down deconditioning in peak [Formula: see text]O2 in young patients with repaired ToF.