Michael Kemal Atalay MD, PhD, Abstract Co-Author: Nothing to Disclose

Amogh Srivastava MD, Presenter: Nothing to Disclose

By virtue of volume overload, shunt lesions such as atrial septal defects (ASD) and anomalous pulmonary veins (APV) are known to cause dilation of involved cardiovascular structures. The degree to which these structures enlarge is evidently dependent on the magnitude of shunting, but this has not been previously quantified. This study uses CMR to determine how shunt severity correlates with ventricular chamber volumes, aortic (Ao) and pulmonary artery (PA) diameters, and ASD size.

We reviewed all cardiac MR studies performed at our institution from January 1, 2004 to December 31, 2010. Adult patients with an ASD or APV clearly identified on CMR—with shunt severity quantified (Qp/Qs)—were included in this study. Patients with left ventricular dysfunction, prior cardiac surgery, or other significant congenital or valvular lesions were excluded. In each case, Qp/Qs was determined either by standard ventricular volume analysis (Simpson’s technique), by phase contrast methods (PC-CMR), or by both. The relationships of various anatomic and volumetric measures with Qp/Qs were determined.

Over the study period, 2139 CMR studies were conducted. In all, 39 (1.7%) patients met inclusion criteria (24 women; 50±16 y; age range: 19-87 y). There were 27 cases of isolated ASD (2 sinus venosus, 22 secundum, 3 ostium primum), 9 cases of APV, and 3 cases of SV-ASD combined with APV. Qp/Qs determined by PC-CMR had good correlation with that found using stroke volume data (r=0.88). Overall, the ratio of RV to LV end-diastolic volumes varies linearly with Qp/Qs with very high correlation (m=1.2, b=0.08, r=0.94). In pure ASDs, mean defect diameter is also linearly related to Qp/Qs with high correlation (m=0.83 cm, b=-0.2 cm, r=0.85). For linear models, end-systolic volume ratio and PA-to-Ao diameter ratios only moderately correlate with with Qp/Qs (r=0.73 & r=0.65, respectively).

Knowledge of shunt severity is important for clinical management. Ventricular end-diastolic volume ratios and mean ASD diameter may be used to accurately quantify Qp/Qs in clinical settings where stroke volume and blood flow measurements are unavailable, such as echocardiography and prospectively gated cardiac CT.

Ventricular end-diastolic volume ratios and mean ASD diameter may be used to accurately quantify shunt severity.

Atalay, M, Srivastava, A, Ventricular End-Diastolic Volume Ratios Correlate Highly with Shunt Severity: Quantification Using MRI.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11013545.html