Assessment of left ventricular function long term after arterial switch operation for transposition of the great arteries by dobutamine stress echocardiography

Abstract

Objectives: To use dobutamine stress echocardiography to determine left ventricular (LV) function and wall motion of children long term after arterial switch operation (ASO) for transposition of the great arteries. Design and patients: 31 patients (24 boys) with ASO performed at a mean (SD) of 15.5 (4.3) days of life were studied at an age of 9.4 (2.0) years. All had normal coronary angiographic findings. LV echocardiographic indexes, including fractional shortening, ejection fraction, rate corrected velocity of circumferential fibre shortening (VCFc), and wall stress, as well as LV wall motion abnormalities were determined at rest and under dobutamine stress. The results were compared with those of 20 healthy age matched control participants. Setting: Tertiary paediatric cardiac centre. Results: Fractional shortening, ejection fraction, and VCFc were significantly lower in patients than in controls at rest (all with p , 0.001). Stress-velocity index detected impaired LV contractility in 19 (61%) patients at rest. An older age at operation (p = 0.01), longer bypass (p = 0.01) and circulatory arrest times (p = 0.045), and an unusual coronary artery pattern (p = 0.059) were associated with impaired resting LV contractility. Dobutamine stress echocardiography unmasked wall motion abnormalities in 23 (74%) patients. Exercise myocardial perfusion scan, performed in 22 patients, showed reversible myocardial perfusion defects in 17. These defects corresponded to segments of hypokinesia as detected by dobutamine stress echocardiography. Conclusion: A significant proportion of children, albeit asymptomatic, had impaired baseline LV contractility and reversible myocardial perfusion defects and mild wall motion abnormalities on stress after ASO. 4 6 However, as long term success of ASO depends on adequacy of the coronary arterial circulation among other factors, the need for coronary artery implantation in ASO remains a cause for concern. Recently, impaired myocardial blood flow during vasodilatation with adenosine and attenuation of coronary flow reserve have been observed in asymptomatic children with TGA a decade after ASO. 8 Although the clinical consequences are unclear, these findings suggest a possibility of long term stress induced LV dysfunction in patients after ASO. Dobutamine stress echocardiography (DSE) has been used for early detection of LV dysfunction in long term childhood cancer survivors 9 and children with thalassaemia 10 through evaluation of myocardial contractile reserve. Furthermore, DSE has been shown to be useful in the diagnosis of myocardial ischaemia secondary to congenital or acquired coronary artery abnormalities.11 12 To our knowledge, DSE has not been applied to evaluate LV function in children with TGA after ASO. Given the previous findings of reduced coronary flow reserve after ASO and sensitivity of DSE in early detection of myocardial dysfunction, we hypothesised that DSE can unmask LV dysfunction in apparently asymptomatic children with TGA after ASO in the long term. To examine this ...

Follow-up outcomes 10 years after arterial switch operation for transposition of the great arteries: comparison of cardiological health status and health-related quality of life to those of the a normal reference population

“…The patients had a significantly lower LV fractional shortening and ventricular circumferential fibre shortening. Factors associated with reduced LV performance were older age at operation, longer cardiopulmonary bypass time and longer circulatory arrest [14]. In our study no association with these factors could be demonstrated.…”

“…Although initial reports on ventricular function after ASO have been encouraging, relatively few studies have been done on longer term function [3,14,16,18] and comparison with healthy controls has hardly been performed [14,16]. Recently, Hui and co-workers compared LV function of 31 patients at a mean of 9.4 years after ASO and 20 healthy controls [14].…”

“…All patients in whom wall motion abnormalities were detected had impaired ventricular performance at rest. All had normal coronaries on angiography [14]. Taylor and co-workers, using MRI, reported myocardial viability defects in 2 of 16 asymptomatic patients at a mean of 10 years after ASO [34].…”

“…Recently, Hui and co-workers compared LV function of 31 patients at a mean of 9.4 years after ASO and 20 healthy controls [14]. The patients had a significantly lower LV fractional shortening and ventricular circumferential fibre shortening.…”

Late coronary complications after arterial switch operation and their treatment

“…It should be noted however that SPET can be normal if both coronary ostia are involved or biased by an old myocardial damage obtained during the earlier bypass surgery [10,11]. Chemical or exercise-induced stress echocardiography has been used in children to evaluate the coronary circulation and myocardial performance under stress and described as a sensitive method [12][13][14]. However, it has not been included in our assessment of children after ASO operation.…”