Comparison of Hemodynamics Using Combined Cardiac Catheterization and Cardiac Magnetic Resonance Data – a Single Center Experience (RF_SA_452)

Patients with congenital heart disease require cardiac catheterization (CC) for physiologic assessment and prognosis. Assessment of hemodynamics in patients with complex congenital heart defects would ideally include differential blood flow quantification to individual vascular beds. The Fick principle, using assumed VO2, is the current standard to calculate Qp, Qs, SVRi and PVRi. Cardiac MRI (CMR) can be used to determine Qp and Qs by direct flow measurement in addition to regional blood flow and has become the gold standard for assessment of blood flow and cardiac output   

We aim to compare Fick-derived and CMR-derived hemodynamics in patients undergoing same day CMR and CC. Our hypothesis is PVR calculated using Fick underestimates PVRi measured by combined CC and CMR-derived hemodynamics. 



Methods: Patients undergoing CC and CMR  on the same day were identified. Qp and Qs were calculated using Fick or directly measured by CMR. The Seckler formula  estimated VO2. PVRi was calculated using a transpulmonary gradient derived from individual lung pressure or an average of the two pulmonary artery pressures and either the left atrial, pulmonary vein, ventricular end-diastolic pressure, or pulmonary artery wedge pressure. Statistical analysis: non-parametric and parametric testing was done depending on the distribution of data. Wilcoxon signed rank was used to compare CC-based and CMR-derived hemodynamics.

Results: We found 36 patients, ages 0.1-14.6 years, with 38 instances of same-day CC and CMR, twenty-seven with univentricular and 9 with biventricular circulation. Fick-derived Qp 4.3 [3.1, 5.6] and Qs 4.1 [3.4, 5.1] overestimates CMR-derived Qp 3.2 [2.8, 3.9] and Qs 3.0 [2.5, 3.4], (Qp P=0.004, Qs P< 0.0001 respectively). Fick-derived Qp:Qs ratio 1.0 [0.6,1.4] underestimated CMR-derived Qp:Qs ratio 1.1[0.9,1.4], P=0.029. CMR-derived flow to the right lung (1.6 L/min [1.4, 2.4] is increased compared to the left lung (1.5 L/min [1.2,1.5], P=0.005). Median CMR-derived right lung resistance is 3 [2.4,4.4] and left 4.3 [2.7,6.6]. CMR derived PVRi 1.7 [1.3, 2.4] tended to be higher than CC-derived PVRi 1.3 [1.1,