RVOT stands for right ventricular outflow tract, the passageway inside your heart that channels blood from the right ventricle up into the pulmonary artery and toward your lungs. On an ultrasound (echocardiogram), it appears as a short, cone-shaped tunnel sitting just below the pulmonary valve. Sonographers measure it routinely because its size and the speed of blood flowing through it reveal important information about how well the right side of your heart is working.
Where the RVOT Sits in Your Heart
Think of the right ventricle as having two jobs: receiving blood (the inflow tract) and pushing it out (the outflow tract). The RVOT is that outflow portion. It begins at a muscular ridge called the supraventricular crest, which separates it from the rest of the right ventricle, and it ends at the base of the pulmonary valve. Structurally, it has two parts: a septal component that shares a wall with the left ventricle, and the subpulmonary infundibulum, a funnel-shaped section that narrows as it leads up to the pulmonary valve.
The muscle fibers in the RVOT run in a different, more parallel orientation than those in the rest of the right ventricle. This design helps the tract squeeze blood efficiently upward into the pulmonary artery with each heartbeat.
How the RVOT Is Seen on Ultrasound
The most common way to visualize the RVOT is through a parasternal short-axis view. The sonographer places the ultrasound probe on the left side of the chest near the third or fourth rib space, with the probe marker pointed toward your left shoulder. This cross-sectional slice shows the aortic valve in the center, with the RVOT wrapping around it on its way to the pulmonary valve. A parasternal long-axis view can also capture the RVOT, though the short-axis view tends to give more reproducible measurements.
During a fetal ultrasound, the RVOT is assessed differently. The sonographer sweeps upward from the standard four-chamber heart view through a series of cross-sectional slices, eventually reaching the outflow tracts and the three-vessel view. In a normal fetus, the pulmonary trunk (the vessel the RVOT feeds into) should appear slightly larger in diameter than the aorta.
Normal RVOT Measurements
Echocardiographers typically measure the RVOT at two points, both taken at the end of the heart’s relaxation phase (end-diastole). The proximal RVOT (called RVOT1) is measured at the level of the aortic valve, from the front wall of the aorta straight out to the free wall of the right ventricle. Normal values are up to 44 mm in men and up to 42 mm in women. The distal RVOT (RVOT2) is measured just below the pulmonary valve, where the tract narrows. Normal values here are up to 29 mm in men and 28 mm in women.
When the RVOT measures larger than these thresholds, it can signal that the right ventricle is dilated, which may point to conditions like pulmonary hypertension or volume overload. A tract that’s too narrow raises concern for obstruction.
What RVOT Obstruction Looks Like
RVOT obstruction means something is partially blocking blood flow between the right ventricle and the pulmonary artery. On ultrasound, the sonographer uses Doppler to measure how fast blood is moving through the tract. Faster-than-normal flow indicates a pressure buildup. A flow velocity above 2.0 meters per second on Doppler is one threshold that has been used to flag obstruction, and a pressure gradient greater than 25 mmHg between the right ventricle and pulmonary artery is generally considered hemodynamically significant, meaning it’s enough to strain the heart.
Hypertrophic cardiomyopathy, a condition where the heart muscle becomes abnormally thick, is one of the most common congenital causes. The thickened muscle physically crowds the outflow tract, especially during contraction. On M-mode ultrasound, you can sometimes see the RVOT narrowing dramatically between heartbeats, with the tract nearly closing during systole (when the heart squeezes) and reopening during diastole (when it relaxes).
RVOT in Congenital Heart Disease
Tetralogy of Fallot is the most well-known congenital condition involving the RVOT. It includes four defects: a narrowed RVOT, a hole between the ventricles, an aorta that sits over the hole instead of purely over the left ventricle, and thickening of the right ventricular wall. On prenatal ultrasound, the RVOT may appear visibly narrow, and color Doppler can show reduced or absent flow through the pulmonary valve area.
In the most severe form, called tetralogy of Fallot with pulmonary atresia (accounting for roughly 20% of all tetralogy cases), the connection between the RVOT and the pulmonary artery is completely closed off. The pulmonary valve tissue appears bright and echogenic on ultrasound and stays shut throughout the entire cardiac cycle. Color Doppler confirms the diagnosis by showing flow through the aorta but none in the area where the pulmonary artery should be. This severe variant occurs in about 10 out of every 100,000 live births.
Why the RVOT Matters for Heart Rhythm Issues
If you’ve had a heart rhythm evaluation, you may have seen “RVOT” on your report for a different reason. A common type of abnormal heart rhythm called RVOT tachycardia originates from the outflow tract itself. It produces a characteristic pattern on an ECG, and cardiologists order an echocardiogram to check whether the RVOT and the rest of the right ventricle look structurally normal. In most cases of RVOT tachycardia the heart appears completely normal on ultrasound, which is actually reassuring, since it helps rule out more serious conditions like arrhythmogenic right ventricular cardiomyopathy. When the echocardiogram is inconclusive, cardiac MRI or other advanced imaging may be used to get a closer look at the tissue.