Background-The aims of this study were to validate MRI-derived right ventricular (RV) pressure-volume loops for assessment of RV myocardial contractility and then to apply this technique in patients with chronic RV pressure overload for assessment of myocardial contractility, ventricular pump function, and VA coupling. Methods and Results-Flow-directed catheters were guided under MR fluoroscopy (1.5 T) into the RV for invasive pressure measurements. Simultaneously, ventricular volumes and myocardial mass were assessed from cine MRI. From sampled data, RV pressure-volume loops were constructed, and maximal ventricular elastance indexed to myocardial mass (E max_i ) was derived by use of a single-beat estimation method. This MRI method was first validated in vivo (6 swine), with conductance techniques used as reference. Bland-Altman test showed good agreement between methods (E max_i ϭ5.1Ϯ0.5 versus 5.8Ϯ0.7 mm Hg · mL Ϫ1 · 100 g

Background-This study was conducted to determine the effects of chronic pulmonary insufficiency (PI) on right (RV) and left (LV) ventricular function in young growing swine. Methods and Results-Six PI and 5 control animals were studied. PI was induced by transcatheter placement of stents across the pulmonary valve. Indices of systolic function (ejection fraction, cardiac output, and cardiac functional reserve), diastolic function (compliance), and myocardial contractility (the slope of the relationship of end-systolic pressure versus end-systolic volume [E max ] and the slope of the dP/dt max -end-diastolic volume relationship [M dP/dt ]) were assessed within 2 days of intervention and 3 months later. MRI was used to quantify PI and ventricular volumes. Conductance catheter techniques were used to obtain indices of contractility and diastolic compliance from pressure-volume relations at rest and under dobutamine infusion. In the PI group, pulmonary regurgitant fraction was 49.2Ϯ5.9% at 3-month follow-up. RV cardiac functional reserve was limited, diastolic function was preserved, and myocardial contractility was altered (E max ϭ2.6Ϯ0.3 mm Hg/mL for the PI group versus 3.5Ϯ0.4 mm Hg/mL for control; PϽ0.01). LV cardiac functional reserve was limited, ventricular compliance decreased, and myocardial contractility was preserved. Conclusions-In the young developing heart, chronic PI alters biventricular systolic function, RV myocardial contractility, and LV diastolic performance.

The extracardiac conduit Fontan procedure can be performed with minimal mortality and morbidity. Improved results may be related to advantages of the extracardiac approach and improved preservation of ventricular and pulmonary vascular function.

Angiographically detectable systemic venous collateral channels develop after bidirectional cavopulmonary anastomosis in a substantial number of patients (33% in the present series) with a variety of forms of a functional univentricular heart. Patients with venous collateral channels can be treated successfully with coil embolization, but the indications for embolization will depend on individual circumstances.

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