RV functional abnormalities secondary to PH-related cardiac remodeling include RV hypokinesis, leftward bowing and/or paradoxical movement of the interventricular septum, RV dysfunction (increased end-diastolic volume, reduced ejection fraction, reduced cardiac index, reduced stroke volume), and pulmonary and tricuspid insufficiency [59-62]. RV mass and LV mass can also be accurately determined, which can then be used to calculate a ventricular mass index (RV mass/LV mass), with a ratio >0.6 being abnormal [61,63,64]. Cardiac MRI shows many of the morphologic changes of PH that are also depicted by chest CT and CTPA: PA enlargement, MPA to adjacent ascending aorta ratio > 1, RV enlargement and hypertrophy, straightening of the interventricular septum, and pericardial thickening and effusion [61,65,66]. Measured parameters of RV ejection fraction, RV end diastolic volume, and RV-PA coupling metrics measured on cardiac MR have been shown to be important prognostic indicators of PH [59,65]. Additional characteristic findings of PH on cardiac MRI include findings on late gadolinium enhancement, T1 mapping, and phase-contrast sequences. Enhancement of the RV insertion points on late gadolinium enhancement imaging is commonly present in individuals with PH and is compatible with fibrosis related to RV stress [60,62,63,67]. T1 mapping will also show abnormally prolonged values at the RV insertion points in PH [68,69]. Cardiac MRI phase-contrast imaging techniques can measure average blood flow velocity of the MPA, which correlates with mPAP. Patients with PH have sluggish PA flow as demonstrated by prolonged acceleration times on phase-contrast imaging. Severity of tricuspid regurgitation can be accurately quantified with 2-D phase-contrast imaging and used to estimate MPA pressure [65,70,71].
Suspected Pulmonary Hypertension. RV functional abnormalities secondary to PH-related cardiac remodeling include RV hypokinesis, leftward bowing and/or paradoxical movement of the interventricular septum, RV dysfunction (increased end-diastolic volume, reduced ejection fraction, reduced cardiac index, reduced stroke volume), and pulmonary and tricuspid insufficiency [59-62]. RV mass and LV mass can also be accurately determined, which can then be used to calculate a ventricular mass index (RV mass/LV mass), with a ratio >0.6 being abnormal [61,63,64]. Cardiac MRI shows many of the morphologic changes of PH that are also depicted by chest CT and CTPA: PA enlargement, MPA to adjacent ascending aorta ratio > 1, RV enlargement and hypertrophy, straightening of the interventricular septum, and pericardial thickening and effusion [61,65,66]. Measured parameters of RV ejection fraction, RV end diastolic volume, and RV-PA coupling metrics measured on cardiac MR have been shown to be important prognostic indicators of PH [59,65]. Additional characteristic findings of PH on cardiac MRI include findings on late gadolinium enhancement, T1 mapping, and phase-contrast sequences. Enhancement of the RV insertion points on late gadolinium enhancement imaging is commonly present in individuals with PH and is compatible with fibrosis related to RV stress [60,62,63,67]. T1 mapping will also show abnormally prolonged values at the RV insertion points in PH [68,69]. Cardiac MRI phase-contrast imaging techniques can measure average blood flow velocity of the MPA, which correlates with mPAP. Patients with PH have sluggish PA flow as demonstrated by prolonged acceleration times on phase-contrast imaging. Severity of tricuspid regurgitation can be accurately quantified with 2-D phase-contrast imaging and used to estimate MPA pressure [65,70,71].