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Re: Pulmonary artery stiffness in arterial switch patients

Dear Editor,

The recent study by Grotenhuis and colleagues demonstrated the increased peak flow velocity across the pulmonary trunk, right ventricular hypertrophy and right ventricular relaxation abnormalities in patients after the arterial switch operation (1). The authors argued that one of the possible causes of the increased peak flow velocity was local scar tissue with loss of pulmonary artery distensibility.

I recognize the soundness of the report. We previously analyzed an input impedance spectrum of pulmonary artery in patients after the arterial switch procedure, and reported the increased pulmonary artery stiffness of them (2). Concerning systemic circulation, many reports have demonstrated that the augmented aortic stiffness, which increases left ventricular pulsatile work, induces left ventricular hypertrophy (3). As for pulmonary circulation, it has reported that the increased pulmonary artery stiffness enhances right ventricular load (4). Therefore, the increased stiffness of pulmonary artery in arterial switch patients would cause right ventricular hypertrophy. I agree with Grotenhuis and colleagues in thinking that careful observation about right ventricular function (and arrhythmia) is needed in follow-up of the patients after the arterial switch procedure.

References

1. Grotenhuis HB, Kroft LM, van Elderen SGC, et al.
Right ventricular hypertrophy and diastolic dysfunction in arterial switch patients without pulmonary artery stenosis.
Heart. 2007;93:1604-1608

2. Murakami T, Nakanishi T, Nakazawa M, et al.
The spectrum of pulmonary input impedance in children with complete transposition after the arterial switch procedure.
Cardiol Young. 1998;8:180-186

3. Ou P, Celermajer DS, Jolivet O, et al.
Increased central aortic stiffness and left ventricular mass in normotensive young subjects after successful coarctation repair.
Am Heart J. 2008;155:187-193