Pressure-Volume Relations in Patients with Single Ventricle: Feasibility and Comparison of Obtainment by 3D-Real Time Echocardiography and Mini Pressure-Wire with Conductance Technology

Objectives: Pressure-volume relations (PVR) provide vital information regarding cardiac pathophysiology and allow assessment of systolic as well as diastolic function. Due to invasiveness and catheter size acquiring PVR by conductance technology (PVRCond) in children is restricted to older age. PVR can also be obtained by 3D-echocardiography (3DE) volume data in combination with simultaneously measured pressure data by a mini pressure-wire (PVR3DE). With this study we aim to investigate the feasibility of obtaining PVR3DE and PVRCond in patients with a single ventricle. Moreover we sought to compare PVR specific parameters acquired by both methods.

Methods: We studied 19 patients (age 9 ± 7 years). 12 with single right, 7 with single left ventricle. PVR3DE and PVRCond were determined in the single ventricle under baseline conditions followed by positive inotropic stimulation with dobutamine 10 µg/kg/min using 3DE with simultaneous recording of ventricular pressure by a mini pressure-wire (Radi, St. Judes) and Cond (CD Leycom).

Results: Obtaining PVR3DE was feasible in all patients; time needed 5–7 minutes. Correct placement and satisfactory signal quality of the conductance catheter could be achieved in only 15 patients under baseline conditions (79%); time needed 10–30 minutes. Under dobutamine stimulation signal quality remained satisfactory in 12 patients (63%). Both methods showed significant increase of End-systolic elastance (Ees) and decrease of the isovolumic relaxation time constant Tau ([Table 1]).

Table 1

	Ees [mm Hg/mL]		Tau [ms]
	3DE	Cond	3DE	Cond
Baseline	3.9 ± 2.2	2.4 ± 2	24.5 ± 6	28.3 ± 9

Bland-Altman-analyses showed: Ees: mean bias 1.6 mm Hg/mL, limits of agreement -4.0–7.3 mm Hg/mL; Tau: mean bias -4.6 milliseconds, limits of agreement -19.9–10.8 milliseconds.

Conclusion: Both methods reflected the changes under dobutamine stimulation in the same way. Obtaining PVR3DE in a single ventricle was feasible and faster than obtaining PVRCond. Achieving correct placement and signal quality of the conductance catheter can be very demanding especially in a single right ventricle resulting in increased time of intervention and potentially more radiation. So other methods to obtain PVR are desirable. PVR obtained by 3DE and mini pressure-wire can serve as a promising and needed alternative to the conductance technology.

Supported by Fördergemeinschaft Deutsche Kinderherzzentren e.V.

No conflict of interest has been declared by the author(s).