Published Online
on July 8, 2009

A more recent version of this article appeared on September 1, 2009

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Original Article

Noninvasive Quantification of Systemic To Pulmonary Collateral Flow: A Major Source of Inefficiency in Patients with Superior Cavopulmonary Connections

Kevin K. Whitehead¹; Matthew J. Gillespie; Matthew A. Harris; Mark A. Fogel and Jonathan J. Rome

Children's Hospital of Philadelphia, Philadelphia, PA

¹ E-mail: whiteheadk{at}email.chop.edu

Background—Systemic to pulmonary collateral flow (SPCF) is common in single ventricle patients (pts) with superior cavopulmonary connections (BDG). Because no validated method to quantify SPCF exists, neither its hemodynamic burden nor clinical impact can be systematically evaluated. We hypothesize that (1) the difference in total ascending aortic (Ao) and caval flow (SVC+IVC) and (2) the difference between pulmonary vein and artery flow (PV – PA) provide two independent estimators of SPCF.

Methods and Results—We measured Ao, SVC, IVC, right (RPA) and left (LPA) PA, left (LPV), and right (RPV) PV flows in 17 BDG pts during routine cardiac magnetic resonance imaging studies using through-plane phase contrast velocity mapping. Two independent measures of SPCF were obtained: (1) Ao – (SVC + IVC). (2) (LPV-LPA) + (RPV-RPA). Values were normalized to body surface area (BSA), Ao, and PV and comparisons made using linear regression and Bland-Altman analysis. SPCF ranged from 0.2-1.4 L/min for (1) and 0.2-1.6 L/min for (2) for an average indexed SPCF of 0.5-2.8 L/min/m² : 11-53% (mean 37%) of Ao and 19-77% (mean 54%) of PV. The mean difference between (1) and (2) was 0.01 L/min (p=0.40, 2 S.D. range -0.45-0.47 L/min).

Conclusions—We present a noninvasive method for the SPCF quantification in pts with BDG. It should provide an important clinical tool in managing these patients. Furthermore, we show that SPCF is a significant hemodynamic burden in many patients with BDG physiology. Future investigations will allow objective study of the impact of collateral flow on outcome.

Key Words: blood flow • collateral circulation • imaging • magnetic resonance imaging • superior cavopulmonary connection • single ventricle