Validity and variability of 3D-echocardiography for measuring right ventricular function.

Today measurement of RV volume is usually performed using cardiac MRI using
short-axis views. Real-time 3D echocardiography is a more easily accessible,
faster and more patient friendly alternative. Before real-time 3D
echocardiography can be used in daily practice more information about
feasibility, accuracy and reproducibility is required.

To compare feasibility, accuracy and intra-and interobserver variability of
short-axis derived versus long-axis derived RV volumes by realtime 3D
echocardiography.

Intervention: Realtime 3D echocardiography will be performed on 45 subjects. To
enhance the quality of the acquired images a contrast agent will be injected in
all subjects.
Methods: Real-time, transthoracic 3D echocardiographic images (IE-33, X3-1
transducer, Philips Medical Systems, Best, The Netherlands) will be obtained
from the apical view. Using on board software (Qlab 5, general imaging view)
the RV and LV volume will be divided into 7 short-axis and alternatively in 7
vertical long-axis slices. Endocardial contours will be manually traced twice
for every frame in 1 cardiac cycle in all slices to compute RV and LV volume
curves by 2 observers. For measurement of the validity and accuracy of realtime
3D echocardiography LV and RV stroke volumes will be compared. The mean
difference will be a measure for accuracy and validity. For measurement of
reproducibility every frame is manually traced twice. The mean difference
between the two measurements will be a measure for reproducibility.

Subjects will visit the department of cardiology echo lab once. There they will
be informed about the entire procedure. They will be asked if they are known
with a history of allergy. No blood samples will be taken. When they meet
inclusion criteria and are negative to exclusion criteria they will sign their
informed consent. Then subjects will enter the testing procedure. The entire
procedure will last 30-60 minutes.
Administration of contrast agents is safe and side effects, if present, are
largely minimal and reversible. Severe allergic reactions have been reported,
but only in 1 on 50,000 patients. To handle these situations the study will be
performed at the department of cardiology echo lab in presence of a
cardiologist. Medication and appliances are present to cope with an adverse or
serious adverse event.
Application of ultrasound is safe. Application of a burst of ultrasound with a
mechanical index of 1.3 during administration of micro bubbles is used in other
studies assessing myocardial perfusion with myocardial contrast
echocardiography, and no problems have been reported regarding this aspect.
There are no personal benefits for the subjects.