- Poster presentation
- Open Access
Diastolic prolongation of forward flow in branch pulmonary artery stenosis
© Chen and Kilner; licensee BioMed Central Ltd. 2012
- Published: 1 February 2012
- Cardiovascular Magnetic Resonance
- Forward Flow
- Arterial Switch Operation
- Branch Pulmonary Artery
- Pulmonary Artery Flow
Diastolic prolongation of forward flow, or diastolic tail is present in unilateral branch pulmonary artery stenosis in patients after the arterial switch operation for transposition of the great arteries and after repair for tetralogy of Fallot. Interestingly, as a result of a diastolic tail, flow through the stenosed artery is comparable to that in the non-stenosed artery and therefore the impact of stenosis may be relieved.
Diastolic prolongation of forward flow, or diastolic tail, is known as an indicator of the hemodynamic impact of aortic coarctation or recoarctation. We have observed similarly tailed flow curves in unilaterally stenosed branch pulmonary arteries (PA) of patients with transposition of the great arteries corrected by arterial switch (TGA-AS) and after repair of tetralogy of Fallot (rToF). We are not aware that this has been described before. We aimed to improve understanding of the nature and possible clinical implications of this pathophysiological finding.
Ten patients, 7 TGA-AS and 3 rToF, aged (20±8 years, 8 male) were found with a diastolic tail in one or other PA. All had at least moderate branch PA stenosis, 7 on the right and 3 on the left. No patient had more than trivial pulmonary valve regurgitation. No other haemodynamically significant lesion was found. The minimum diameter of the stenosed artery was significantly smaller than the non-stenosed artery, 5.1±2.1mm vs 13.7±5.0mm, p<0.001 but, surprisingly, volumes of flow through the respective arteries were comparable, 3.0±1.5L/min on the stenosed side vs 3.4±2.2L/min, p=0.6. Flow curves through the stenosed and the non-stenosed arteries were averaged for all patients and compared with those averaged from controls (Figure 1). A diastolic tail curve was present only in stenosed arteries of patients. In spite of near competent valves, early diastolic regurgitant flow was seen from the non-stenosed PAs of patients (Figure 1A), regurgitation fraction 16±9% vs 0.2±0.3% from stenosed arteries, p<0.001. No significant regurgitation was observed in the right or left PAs of volunteers (regurgitation fraction 0.9±0.2% and 1.9±0.1% respectively); although there was slight mid diastolic forward flow (Figure 1B), attributable to proximal PA compliance.
In the presence of a competent pulmonary valve, flow through a stenosed branch PA, although limited in systole, may carry on into diastole, delivered by the compliance of contralateral PA and pulmonary trunk. This may alleviate the impact of unilateral stenosis.
There is no funding support for this study.
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