Diagnosing double-chambered right ventricles
In this video, you'll learn about double-chambered right ventricles (DCRVs), why they occur, and some tricks that you can use to help you make a sound diagnosis using echo.
A double-chambered right ventricle (DCRV) occurs when the right ventricle is divided by anomalous muscle bundles. In this video, from our Echo Masterclass: Adult Congenital Heart Disease course, you'll learn about DCRVs, why they occur, how non-standard views can help to separate overlapping signals, and some tricks that you can use to help you make a sound diagnosis using echo.
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[00:00:00] In the right ventricle, anomalous muscle bundles or an abnormally positioned moderator band can cause differential pressure leading to what we term a double-chambered right ventricle. Double-chambered right ventricles are associated with ventricular septal defects 70% of the time but can also be associated with pulmonary stenosis and atrial septal defects. I'll use the short axis view
[00:00:30] to discuss this concept because we can see both inflow and outflow portions of the right ventricle. Here are the anomalous muscle bundles which cause obstruction to right ventricular outflow. This causes a backup of pressure proximal to those bundles in the inflow region which leads to a high-pressure chamber. On the distal side of the bundles, the pressure remains normal or even low. So you can see we have two different pressure compartments within the same right ventricle and this is why the condition is called
[00:01:00] a double-chambered right ventricle. So let's say we have a significant obstruction leading to an intracavity pressure of 97 mmHg. That means that the proximal chamber will be very high pressure, and the tricuspid regurgitation jet will be a very high velocity. They can also be a ventricular septal defect which usually enters the high-pressure chamber. Because of the severe intracavity gradient within the right ventricle, there won't be much pressure difference
[00:01:30] between the left ventricle and the high-pressure chamber, so the VSD velocity will be low. So now we have a high tricuspid regurgitation velocity and a low velocity ventricular septal defect which both suggest pulmonary hypertension. However, we know there is an intracavity gradient, so these parameters do not reflect pulmonary pressure in this case, you can see how important it is to evaluate the gradient properly. On
[00:02:00] 2D imaging, we can see the muscle bundles obliterating the outflow. Notice the ventricular septal defect. It enters into the right ventricle before the bundles. So entering the high-pressure chamber, we can expect that it will be a low velocity. Here we see the red color flow across the ventricular septal defect, but it doesn't look turbulent like VSD jets normally do. It's quite laminar suggesting that the right ventricular pressure is high. Now we can see turbulent flow at the site of the muscle
[00:02:30] bundles. Let's take a look at the gradient. That's a high gradient. There is a danger here that if this gradient gets higher, such as with exercise, it will cause the high-pressure chamber to reach systemic pressures and the flow of the ventricular septal defect will reverse which means the flow will go from right to left causing cyanosis and warranting surgery to resect the muscle bundles and close the ventricular septal defect. This is another view of the same patient where you can see
[00:03:00] the effect of the muscle bundles. The case I showed was a straightforward case, it was really severe. But sometimes the assessment is more difficult. Let's get to work. This is a child who presented with double-chambered right ventricle. There is turbulent flow both in the right ventricular outflow and across the ventricular septal defect. When we bring the cursor into view to assess the gradient, it transects both the ventricular septal defect and the right ventricular outflow
[00:03:30] so it's difficult to know which gradient will be displayed, both are systolic and towards the transducer so they have the same timing and direction. This problem is not uncommon in double-chambered right ventricles and so a lot of non-standard views might help to tease out the two signals. When ventricular septal defects and right ventricular gradients can't be differentiated, monitoring for an increase in the tricuspid regurgitation velocity over time can suggest a worsening intracavity gradient.
[00:04:00] Up to 70% of patients with double-chambered right ventricle also have a ventricular septal defect which usually enters the high-pressure chamber and therefore has laminar flow that makes them very easy to miss if we rely on the turbulent jet. If a right ventricular gradient is found on an echo, always look carefully for a ventricular septal defect and be cautious in differentiating the signals. Sometimes it's not possible to be sure which is which.