Author + information
- Published online October 1, 2018.
- Laura Mercer-Rosa, MD, MSCE∗ (, )
- Mark A. Fogel, MD,
- Stephen M. Paridon, MD,
- Jack Rychik, MD,
- Wei Yang, PhD and
- Elizabeth Goldmuntz, MD
- ↵∗Division of Cardiology, The Children's Hospital of Philadelphia, 34th and Civic Center Boulevard, Suite 8NW35, Philadelphia, Pennsylvania 19104
Antegrade end-diastolic flow in the main pulmonary artery with atrial contraction (ADF) is observed in patients with repaired tetralogy of Fallot (TOF) and is thought to represent restrictive right ventricular (RV) physiology. We sought to investigate the association of ADF with pulmonary insufficiency (PI), RV function, and exercise performance in this patient population.
Subjects with repaired TOF underwent echocardiograms (echo), cardiac magnetic resonance (CMR), and exercise stress testing (EST) as part of a study protocol (1).
Digitally stored echo images were used for ADF measurements, performed by a single blinded observer (L.M.R.). ADF was defined as antegrade flow in the main pulmonary artery with atrial contraction, interrogated by pulsed-wave Doppler, and considered present if visualized in 3 consecutive beats. No respiratory tracings were available. Phase-contrast velocity mapping was performed in the pulmonary artery to assess ADF. A previously published EST protocol was used (2).
Continuous variables were described using mean ± SD or median (interquartile range). Categorical variables were described using count (%). Student’s t-tests were used to compare differences between groups by ADF status, and logistic regression was used to identify factors associated with ADF. All p values < 0.05 were used for significance (Stata 11.0, Stata Corp, College Station, Texas).
A total of 88 subjects with TOF and pulmonary stenosis were included, all had a transannular patch and no residual pulmonary stenosis. All echos were without sedation and 30 (36%) of the CMR were performed under sedation. No arrhythmias were documented on echo electrocardiogram tracings. There was no difference in ADF detection rate by CMR (sedated or unsedated) or echo. The CMR ADF+ group had more severe PI and greater RV dilation and higher stroke volume than the ADF- group, but comparable ventricular ejection fraction. Pulmonary regurgitant fraction was the only factor associated with ADF, independently of patient factors.
ADF by CMR was directly associated with oxygen pulse, but not with any other EST parameters. ADF by echo was directly associated with physical working capacity and percentage of predicted maximum oxygen consumption in the group that reached a maximal EST (Table 1).
Continued efforts have been made to better define determinants of outcomes in TOF. Restrictive RV physiology has been shown to be a presumably protective phenomenon, associated with less severe PI by echo and superior exercise performance (2). In this study we report that ADF is commonly identified, with no significant difference in detection rate by echo and CMR and is associated with worse PI but with superior exercise performance in the echo ADF group that achieved a maximal exercise test. Similar to previous studies, ADF was commonly observed on CMR and echo, regardless of CMR sedation status, therefore even though the method used to detect ADF differs between echo and CMR, these imaging modalities can be potentially interchangeable for this assessment (1).
We found that ADF was directly associated with severity of PI, RV dilation, and stroke volume. These findings are in contrast with the initial description of restrictive physiology as a protective phenomenon associated with smaller cardiac silhouettes and less severe PI, but similar to others (1,3). We postulate that ADF occurs in the setting of an ineffective native pulmonary valve that fails to impede antegrade flow during atrial contraction, in the presence of greater pulmonary arterial bed capacitance. Finally, ADF was associated with better oxygen consumption in the ADF plus echo patients that achieved a maximal test, similarly to the original report on ADF, but contrary to others (1,4). This finding merits future study since our study does not allow us to infer whether ADF results in better oxygen consumption or, alternatively, better oxygen consumption reflects a particular hemodynamic state in patients with more severe PI that allows for ADF. Furthermore, we were limited by the absence of respiratory tracing on echo and cannot directly compare our findings to others.
In conclusion, ADF is associated with worse PI and possibly with better aerobic capacity. ADF likely represents a complex phenomenon that reflects a combination of greater RV volume, atrial contractility, and pulmonary arterial bed capacitance, with decreased RV compliance.
Please note: This work was funded by National Institutes of Health grants P50-HL74731 (E.G. and L.M.R.), T32-HL007915 (L.M.R.), and K01HL125521 (L.M.R.). The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2018 American College of Cardiology Foundation
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