Abstract 13774: Impaired Lung Perfusion and Altered Perfusion Distribution in Patients With Hemodynamic Abnormalities, A Quantitative Lung Perfusion Study by MRI
Background: Pulmonary vascular pressure and flow are closely related to cardiac hemodynamics. However, it is unclear how lung perfusion changes at the tissue level in response to hemodynamic abnormalities. We sought to investigate the relationship of lung perfusion to cardiac hemodynamics using lung perfusion quantitation by MRI.
Methods: Lung perfusion was quantitatively analyzed in 10 normal subjects and 25 patients who underwent clinically indicated left and right heart catheterization and same day research cardiac MRI on a 1.5 T scanner. A total of 210 lung sections were quantitatively analyzed using a custom model-independent deconvolution program in left and right anterior, mid and posterior lung fields. Global lung perfusion was determined as the average of all 6 sections Cardiac index (CI) was calculated using phase contrast imaging of the main pulmonary artery (PA) indexed by body surface area.
Results: Mean age was 59 years in patients and 44 in controls (p=0.02). Lung perfusion wassignificantly lower in patients with reduced CI (<2.5 L/min/m2) 96±23 ml/100ml/min vs 145±39 ml/100ml/min in patients with preserved CI (≥ 2.5 L/min/m2) (p=0.004). As in normal controls lung perfusion in patients showed a linear gravitational gradient, with the highest perfusion in posterior and the lowest in anterior lung fields. The gradient was disrupted with near equalization of all segmental perfusion in patients with significant hemodynamic abnormality. The decreased slope of the perfusion gradient from anterior to posterior lung fields in patients was associated with decreased global lung perfusion (r=0.629, p=0.001), decreased oxygen saturation in PA (r=0.690, p<0.001) and in aorta (r=0.697, p<0.001), increased RVSP (r=-0.611, p=0.002), RVEDP (r=-0.671, p<0.001) and LVEDP (r=-0.625, p<0.001). The slope was 0.193 in patient with LVEDP > 12 mmHg when compared to 0.400 in those with LVEDP ≤ 12 mmHg and 0.505 in normal controls (p=0.001).
Conclusion: Reduced lung perfusion was associated with an impaired cardiac index. The normal gradient in lung perfusion from anterior to posterior lung segments was nearly abolished in patients with significant hemodynamic derangements, demonstrating the impact of heart-lung interaction on the pulmonary circulation.
- © 2011 by American Heart Association, Inc.