CONGENITAL HEART DISEASE

Right ventricular hypertrophy and diastolic dysfunction in arterial switch patients without pulmonary artery stenosis

H B Grotenhuis¹, L J M Kroft¹, S G C van Elderen¹, J J M Westenberg¹, J Doornbos², M G Hazekamp², H W Vliegen³, J Ottenkamp² and A de Roos¹

¹ Department of Radiology, Leiden University Medical Centre, The Netherlands
² Department of Paediatric Cardiology and Cardiothoracic Surgery, CAHAL (Centre for Congenital Anomalies of the Heart), Leiden, The Netherlands
³ Department of Cardiology, Leiden University Medical Centre, The Netherlands

Correspondence to:
Dr Albert de Roos, Leiden University Medical Centre, Department of Radiology, C2-S, Albinusdreef 2, 2300 RC Leiden, The Netherlands; A.de_Roos{at}lumc.nl

Objective: To assess pulmonary flow dynamics and right ventricular (RV) function in patients without significant anatomical narrowing of the pulmonary arteries late after the arterial switch operation (ASO) by using magnetic resonance imaging (MRI).

Methods: 17 patients (mean (SD), 16.5 (3.6) years after ASO) and 17 matched healthy subjects were included. MRI was used to assess flow across the pulmonary trunk, RV systolic and diastolic function, and RV mass.

Results: Increased peak flow velocity (>1.5 m/s) was found across the pulmonary trunk in 14 of 17 patients. Increased RV mass was found in ASO patients: 14.9 (3.4) vs 10.0 (2.6) g/m² in normal subjects (p<0.01). Delayed RV relaxation was found after ASO: mean tricuspid valve E/A peak flow velocity ratio = 1.60 (0.96) vs 1.92 (0.61) in normal subjects (p = 0.03), and E-deceleration gradients = –1.69 (0.73) vs –2.66 (0.96) (p<0.01). After ASO, RV mass correlated with pulmonary trunk peak flow velocity (r = 0.49, p<0.01) and tricuspid valve E-deceleration gradients (r = 0.35, p = 0.04). RV systolic function was well preserved in patients (ejection fraction = 53 (7)% vs 52 (8)% in normal subjects, p = 0.72).

Conclusions: Increased peak flow velocity in the pulmonary trunk was often observed late after ASO, even in the absence of significant pulmonary artery stenosis. Haemodynamic consequences were RV hypertrophy and RV relaxation abnormalities as early markers of disease, while systolic RV function was well preserved.

Abbreviations: A, atrial kick phase; ASO, arterial switch operation; E, early filling phase; EDV, end diastolic volume; EF, ejection fraction; ESV, end systolic volume; MRI, magnetic resonance imaging; PT, pulmonary trunk; RV, right ventricular; SV, stroke volume; Vmax, maximum blood flow velocity

Keywords: arterial switch operation; pulmonary artery; right ventricle; magnetic resonance imaging; congenital heart disease

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