Effect of Abnormal Pulmonary Flow Distribution on Ventilatory Efficiency and Exercise Capacity After Arterial Switch Operation for Transposition of Great Arteries

doi:10.1016/j.amjcard.2010.05.035

The American Journal of Cardiology

Volume 106, Issue 7, 1 October 2010, Pages 1023-1028

https://doi.org/10.1016/j.amjcard.2010.05.035 Get rights and content

Patients with anatomic repair of transposition of the great arteries (TGA) can present with branch pulmonary artery (PA) stenosis; however, its relation to an abnormal cardiopulmonary response to exercise is unknown. We investigated the relation between the PA anatomy and pulmonary blood flow (PBF) distribution and the cardiopulmonary response to exercise in patients with anatomic repair of TGA. We used cardiopulmonary exercise testing and magnetic resonance imaging to study 55 consecutive patients (62% male; age 14.4 ± 2.3 years) who had undergone neonatal anatomic repair of TGA. The peak oxygen uptake and slope of carbon dioxide elimination/minute ventilation was 79 ± 15% of predicted and 29.8 ± 3.8, respectively. Abnormal peak oxygen uptake (R = 0.363, p = 0.0082) and slope of carbon dioxide elimination/minute ventilation (R = 0.612, p <0.0001) values were associated with an abnormal right/left PBF distribution. However, although an increased ventilatory response to exercise appeared to be primarily related to an abnormal right/left PBF distribution, exercise capacity appeared to be related to the extent of the proximal PA branches and main PA stenosis (R = 0.476, p = 0.0004), suggesting that mechanical obstruction to PBF during exercise could be the main mechanism causing an abnormal exercise capacity. In conclusion, an abnormal PBF distribution related to branch PA stenosis or hypoplasia was associated with a reduced exercise capacity and increased ventilatory drive during exercise in patients with anatomic repair of TGA. Cardiopulmonary exercise test data can complement the anatomic and magnetic resonance imaging data in selecting those lesions that are functionally important.

Section snippets

Methods

As a part of a clinical follow-up protocol, all patients who have undergone the arterial switch operation for TGA at our institution undergo surveillance investigations, including a cardiopulmonary exercise test and magnetic resonance imaging, during the transition to adult care. From January 2003 to March 2009, 60 consecutive patients prospectively completed the clinical protocol. None of the patients studied had a known coronary obstruction, had evidence of pulmonary arterial hypertension, or

Results

The right and left PA flow distribution on magnetic resonance imaging was not determined in the first 5 patients and these patients were excluded from the present analysis. The remaining 55 patients represented the cohort analyzed in the present study (mean age 14.4 ± 2.3 years, range 9 to 19; 34 males, 62%). All patients had undergone the arterial switch operation with the Lecompte maneuver in the neonatal period, and 41 had undergone balloon atrial septostomy before surgery. Of the 55

Discussion

In the present study, we have shown that in patients with neonatal anatomic surgical repair of TGA, an abnormal PBF distribution is associated with reduced exercise capacity and an increased ventilatory response to exercise. The results of our study are important, because they identify important clinical features in a group of completely asymptomatic subjects who could otherwise be considered as having had a good long-term outcome after neonatal repair of TGA. Reduced exercise capacity and an

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The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.
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This study sought to determine whether pulmonary artery intervention in patients with unilateral proximal pulmonary artery stenosis (PAS) improves exercise capacity, abnormal ventilatory response to exercise, and symptoms.
Stenosis of the branch pulmonary arteries results in pulmonary blood flow maldistribution (PBFM). The resulting ventilation–perfusion mismatch is associated with an increased ventilatory response to exercise and decreased exercise capacity. It is unclear if technical success in relieving branch PAS translates to clinical improvement in exercise capacity and ventilatory response.
Twenty patients with biventricular circulation and a minimum 10% PBFM who underwent transcatheter relief of PAS were enrolled in a multi-institutional prospective cohort study. Pre- and post-procedure assessment of the degree of PBFM, exercise capacity, ventilatory response to exercise, and subjective assessment of breathlessness were collected and analyzed.
Technical success was achieved in all patients with significant angiographic improvement in minimal lumen diameter (p = 0.001) and peak gradient (p = 0.001). Median PBFM improved (19.5% [range 12.0% to 31.0%] before vs. 7.0% [range 0% to 33.0%] after; p = 0.003). Exercise capacity was low at baseline and improved significantly post-intervention; percent predicted peak oxygen consumption improved from 70% (range 45% to 96%) to 83% (range 47% to 121%) (p = 0.02). Percent predicted oxygen pulse improved (p = 0.02). Ventilatory response to exercise improved; ventilatory equivalent of carbon dioxide slope post-intervention decreased to 29.3 versus 32.5 pre-intervention (p = 0.01). Subjective assessment of dyspnea improved. Five patients with minimal improvement in PBFM also showed minimal improvement in exercise parameters.
Successful relief of unilateral branch PAS results in significant improvements in exercise capacity, ventilatory efficiency, and symptoms.
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Patients with congenital heart disease and native or palliated conditions are at risk to develop pulmonary hypertension (PH) in later life. Screening for PH is currently performed by regular echocardiographic follow-up, which appears to be difficult in several congenital conditions. This study evaluated the screening for PH in congenital heart disease by cardiopulmonary exercise testing (CPET).
We analyzed our database including all patients with congenital heart disease referred for CPET in our institution from June 2001 to September 2013 and identified 683 patients who had an accompanied heart catheterization less than 6 month after CPET. Those 130 patients with proven PH were compared with the other 563 patients with congenital heart disease but without PH.
Peak oxygen uptake was the most discriminative variable, showing two thresholds at 16.3 mL/min per kg and 25.2 mL/min per kg. The highest specificity of 95% for PH was found in patients with a peak oxygen uptake of 16.3 mL/min per kg or less and a breathing reserve of 37.4% or less. In patients with a peak oxygen uptake exceeding 16.3 mL/min per kg, there was a high specificity of 86.3% but a low sensitivity of 53.1%. With 25.2 mL/min per kg as the threshold, the sensitivity for PH was only 10.0%.
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Citation Excerpt :
Exercise testing has been proposed as a useful adjunct to anatomic and SCD risk assessment. Exercise testing may help determine the hemodynamic significance of a particular structural problem (95). In general, patients with normal structure and normal coronary arteries have a normal cardiopulmonary response to exercise after the ASO, and are at low risk for SCD (96).
The American College of Cardiology Adult Congenital and Pediatric Cardiology (ACPC) Section had attempted to create quality metrics (QM) for ambulatory pediatric practice, but limited evidence made the process difficult. The ACPC sought to develop QMs for ambulatory pediatric cardiology practice. Five areas of interest were identified, and QMs were developed in a 2-step review process. In the first step, an expert panel, using the modified RAND-UCLA methodology, rated each QM for feasibility and validity. The second step sought input from ACPC Section members; final approval was by a vote of the ACPC Council. Work groups proposed a total of 44 QMs. Thirty-one metrics passed the RAND process and, after the open comment period, the ACPC council approved 18 metrics. The project resulted in successful development of QMs in ambulatory pediatric cardiology for a range of ambulatory domains.
Main pulmonary artery area limits exercise capacity in patients long-term after arterial switch operation
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Citation Excerpt :
This was potentially mediated by increased aortic wall stress of the dilated root, fibrous tissue, and intrinsic wall abnormalities near the suture line and pulmonary artery branches embracing the aorta after the Lecompte maneuver.17 Most of these features could theoretically also affect distensibility of the MPA and branches, contributing to a functional stenosis on exercise.7,22 This study approximated distensibility of the pulmonary branches by relative area change, which is uncorrected for pulse pressure, because our study protocol did not include invasive measurements.
Despite excellent survival in patients after the arterial switch operation, reintervention is frequently required and exercise capacity is decreased in a substantial number of patients. This study relates right-sided imaging features in patients long-term after the arterial switch operation to exercise capacity and ventilatory efficiency to investigate which lesions are functionally important.
Patients operated in the UMC Utrecht, the Netherlands (1976-2001) and healthy controls underwent cardiac magnetic resonance imaging and cardiopulmonary exercise testing within 1 week. We measured main, left, and right pulmonary artery cross-sectional areas, pulmonary blood flow distribution, peak oxygen uptake, and minute ventilation relative to carbon dioxide elimination.
A total of 71 patients (median age, 20 [12-35] years, 73% were male) and 21 healthy controls (median age, 26 [21-35] years, 48% were male) were included. Main, left, and right pulmonary artery areas were decreased compared with controls (190 vs 269 mm²/m², 59 vs 157 mm²/m², 98 vs 139 mm²/m², respectively, all P < .001); however, pulmonary blood flow distribution was comparable (P = .722). Peak oxygen uptake and minute ventilation relative to carbon dioxide elimination were 88% ± 20% and 23.7 ± 3.8, respectively, with 42% and 1% of patients demonstrating abnormal results (≤84% and ≥34, respectively). The main pulmonary artery area significantly correlated with peak oxygen uptake (r = 0.401, P = .001) and pulmonary blood flow distribution with minute ventilation relative to carbon dioxide elimination (r = −0.329, P = .008). Subanalysis (<18, 18-25, >25 years) showed that the main pulmonary artery area was smaller in older age groups. In multivariable analysis, the main pulmonary artery area was independently associated with peak oxygen uptake (P = .032).
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: Dr. Taylor was funded by grant SRF/08/01/018 from the National Institute for Health Research, Twickenham, United Kingdom; the magnetic resonance laboratory was funded by grant CI/05/010 from the British Heart Foundation, London, United Kingdom.

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Congenital heart diseaseEffect of Abnormal Pulmonary Flow Distribution on Ventilatory Efficiency and Exercise Capacity After Arterial Switch Operation for Transposition of Great Arteries

Section snippets

Methods

Results

Discussion

J Thorac Cardiovasc Surg

Ann Thorac Surg

Am J Cardiol

J Am Coll Cardiol

Am J Cardiol

Am Heart J

Cardiorespiratory exercise function after the arterial switch operation for transposition of the great arteries

Eur Heart J

Declining aerobic capacity of patients with arterial and atrial switch procedures

Pediatr Cardiol

Congenital heart disease
Effect of Abnormal Pulmonary Flow Distribution on Ventilatory Efficiency and Exercise Capacity After Arterial Switch Operation for Transposition of Great Arteries