8 ( Figure 1) It is conceptually possible to quantify APC blood flow by subtracting the pulmonary arterial from the pulmonary venous blood flow volume. To date, no noninvasive and readily applicable method has been proposed to quantify APC blood flow in patients with functionally single ventricles, except for in a case report, using MRI. Inuzuka et al 7 recently used nuclear imaging in combination with catheterization to quantify APC flow in BCPC patients. Furthermore, it requires intracardiac access, which is not otherwise necessary when extracardiac modifications or catheter laboratory completions of the Fontan procedure are performed. This approach, although of academic value in elucidating the magnitude and risk factors for APCs, is not helpful in the patients’ clinical management before the Fontan operation and does not allow for follow-up after the operation. 1,6 Ichikawa et al 3 and Bradley et al 6 quantified the blood flow through APCs during cardiopulmonary bypass at the time of the Fontan operation by measuring the amount of blood returning to the left atrium and relating it to the pump flow delivered via the aortic cannula.
1 Conventional angiographic grading of APCs is neither objective nor quantitative as the extent of visualization of the APCs varies widely according to where, how fast, and how much contrast medium is injected. The contradicting nature of these reports may be related to the difficulty in assessing the magnitude of blood flow through collaterals angiographically. Patients with a previous right-sided modified Blalock-Taussig shunt had more collateral flow to the right lung than those without.Ĭonclusions- APC blood flow can be noninvasively measured in bidirectional cavopulmonary connections and Fontan patients, using MRI in the majority of patients and results in a significant left-to-right shunt. Qp/Qs was negatively correlated with a younger age at the time of the bidirectional cavopulmonary connections operation ( r=0.62, P=0.01) and positively correlated with the age at the time of the Fontan completion ( r=0.81, P=0.01). The mean inaccuracies corresponded to 7.9�14.5% and 7.1�13.6% of ascending aortic flow in groups A and B, respectively. The ratio of pulmonary to systemic blood flow (Qp/Qs) was 0.93�0.26 in group A and 1.27�0.16 in group B. APC blood flow was calculated by subtracting the blood flow volume through the pulmonary arteries from that through the pulmonary veins. Sixteen studies were performed after the bidirectional cavopulmonary connections (group A) and 8 after the Fontan operation (group B). Methods and Results- APC blood flow was quantifiable in 24 of 36 retrospectively analyzed MRI studies. We aimed to quantify APC flow after bidirectional cavopulmonary connections and Fontan completions, using phase-contrast MRI, and to identify risk factors for the development of APCs.