Echocardiographic Identification of Pulmonary Artery Flow Reversal: An Indicator of Adverse Outcomes in Single Ventricle Physiology.
Spearman AD, Ginde S, Goot BH, Schaal AM, Feng M, Pan AY, Frommelt MA, Frommelt PC.
Pediatr Cardiol. 2020 Jul 24. doi: 10.1007/s00246-020-02421-z. Online ahead of print.
Take Home Points:
- Pulmonary artery flow reversal in patients with palliated single ventricular physiology is the continuous reversal of blood flow from the pulmonary artery into the contralateral pulmonary artery.
- Compared to patient without pulmonary artery flow reversal, patients with such physiology were associated with:
- Longer length of stay post superior cavopulmonary connection surgery;
- Less probability of eventual Fontan completion; and
- Lower 10-year transplant-free survival
Commentary from Dr. MC Leong (Kuala Lumpur), section editor of ACHD Journal Watch: In the absence of a forward pulmonary arterial flow, palliated single ventricle, either in the form of a superior cavopulmonary connection (Glenn shunt) or a total cavopulmonary connection (Fontan), is non-pulsatile and unidirectional, i.e. from the cavopulmonary shunt into the pulmonary arteries. Pulmonary artery flow reversal is the continuous reversal of blood flow from the pulmonary artery into the contralateral pulmonary artery as detected by Color Doppler (Figure 1).
The authors retrospectively reviewed all patients seen at their centre from 1999-2019 with single ventricle congenital heart disease and superior cavopulmonary connection and compared the clinical outcomes between those with reversal of blood flow and those without (Table 1). A total of 560 patients (21, 3.8% with pulmonary artery flow reversal) were recruited. Over the median follow up period of 8.2 years (median 5.3[range 0.2-20.2] years for the pulmonary artery reversal group and median 8.2 years [range <0.1-20.5] years for the non-reversal group, patients with flow pulmonary artery reversal was associated with a poorer outcome. They are associated with a poorer 10-year transplant-free survival, a longer post-operative length of stay (Figure 2-3). However, the 10-year overall survival and the post-operative length of Fontan stay were comparable to those of the non-reversal group. Of patients older than 2 years old who had pulmonary artery flow reversal, only 4 out of 11 (36.4%) proceeded to Fontan completion. They either died (n=4), underwent orthotopic heart transplant (n=1) or remain with superior cavopulmonary connection physiology (n=2). Heterotaxy was not found to be associated with pulmonary artery flow reversal. In the article, the authors mentioned that they detected pulsatile retrograde flow into the pulmonary artery suggesting the presence of aorto-pulmonary collateral arteries.
The authors demonstrated that patients who had pulmonary artery flow reversal had a poorer clinical outcome. The study could pave the way for a new noninvasive indicator to predict patients with poorer long-term prognosis and aid in decision making and clinical management. Pulmonary artery flow reversal is easy to diagnose and is cost-efficient. The logic behind its occurrence is plausible. Ipsilateral pulmonary artery which is high in pressure or obstructed tended to receive less pulmonary blood flow and hence blood tends flow to the contralateral pulmonary artery. Unfortunately, the incidence of pulmonary artery flow reversal is not high, the study may not have the power to associate it with poorer long term outcomes convincingly. We may have to await more studies before this concept translates into a solid evidence.