Echo Case: What the Echo Doesn't See

Ronald H Wharton, MD


March 15, 2016

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Ronald H Wharton, MD: Greetings, this is Dr Ronald Wharton. I am a cardiologist at Montefiore Medical Center in Bronx, New York. I'm showing you a little case vignette that I thought was worth seeing, because frankly, I hadn't seen one of these before. I titled this, "What the Echo Doesn't See."

Here's the history. A 45-year-old gentleman is undergoing preemployment medical screening. He has a chest X ray that reports an enlarged cardiac silhouette. He's asymptomatic.

Here's his electrocardiogram in the next slide. I think you'd all agree that this is a pretty normal electrocardiogram.

Here is an echocardiogram that was ordered because of the chest X-ray finding. A parasternal long axis, standard 2-D image. You can see the left ventricular (LV) function looks normal, but the right ventricle (RV) looks quite enlarged. On 2-D imaging, the mitral and aortic valves grossly look normal.

Here you can see an M-mode through the LV mid-cavity going through the right ventricle, the interventricular septum and then to the inferolateral wall. You'll notice that there is paradoxical septal motion and also there is an exaggerated early diastolic dip, which is to say that when the mitral and tricuspid valves open, it looks like the RV filling is a little exaggerated compared with the LV filling, so that the septum has an exaggerated dip into the LV and early diastole.

Here we have a parasternal long axis. Now with color, you'll notice that the color flow here through the mitral and aortic valves is normal.

Here we have a pulsed-wave Doppler through the right ventricular outflow tract. You'll notice that the right ventricular ejection period is 290 ms, which is normal. The velocity through the right ventricular outflow tract (RVOT) is normal, so this doesn't look particularly unusual in any way. The flow through the RV looks normal, could it be a little exaggerated? It's possible, but one parameter that we don't know for sure is the diameter of the RVOT. To calculate the flow precisely, we would need that parameter. Most echos don't have that parameter. But certainly, the flow here looks good.

In the next slide you can see trivial pulmonic regurgitation and at least from these two slides, you could infer that there is no pulmonary hypertension present.

We now go to the apical four-chamber view. You'll notice again the right side of the heart looks enlarged, but the RV function grossly looks normal, the atrial sizes look normal, the mitral valve looks normal. Again, the only remarkable thing here is the size of the right ventricle.

In this slide, we have a color view of the tricuspid regurgitation, which you or I would characterize as no more than mild.

In this continuous-wave Doppler through the tricuspid valve, the peak velocity is about 2.6 m/sec. That would argue against any significant elevation in the PA pressure. The PA pressure is probably in the vicinity of about 31 or 32 mm Hg.

In the next slide, we see a pulsed-wave Doppler through the right superior pulmonary vein, and you'll notice that there is an S wave and a D wave and the two waves are very well demarcated. This would not be in any way unusual.

Why is the right side of the heart enlarged? The first thing one always thinks about in an asymptomatic person is an atrial septal defect (ASD) that never got picked up. But the electrocardiogram was normal. Typically, with an ASD, there's an incomplete right bundle branch block with a left- or a right-axis deviation depending on whether it's a primum or secundum ASD. There are sinus stenosis ASDs that a transthoracic echocardiogram would not see. The lack of fusion of the S and D waves in the pulmonary-vein Doppler argues against a primum or secundum ASD.

The tricuspid valve appears where it's supposed to be. That also argues against any primum ASD. We don't see any flow across the atrial septum.

What else do we see? We see the RV systolic function is normal, even though the RV is dilated. The pulmonary valve flow pattern is normal. The PA pressure is virtually normal. If it's elevated, it's trivially so.

What do we do next? Should we have done a repeat study with agitated saline? Should we do a CT scan? Should we do an MRI? It's hard to say that there's a real likelihood of a primum or secundum ASD here. A sinus stenosis ASD is not impossible. Again, that's typically where one sees anomalous drainage of the right superior pulmonary vein coming into the right atrium from the very, very superior aspect of the interatrial septum. Should we do a CT scan? Should we do a cardiac MRI? What would the next logical study be?

Before we had a chance to figure that out, the referring cardiologist had already done a CT scan of the chest and this is what it showed. It showed that there was partial anomalous pulmonary vein drainage returning to the right side of the heart. So, this was not a standard pulmonary vein—one of the big four that come into the left atrium. Just one segment of the left upper lobe of the lung had a pulmonary vein draining into the left brachiocephalic vein, and that anomaly was the reason the chest X ray looked abnormal. The radiologist actually commented that this was typically an isolated finding without associated cardiac anomalies and usually found in asymptomatic patients.

I'd never heard of this, so I figured I'd show it because many of you may not have heard of this either.

The take-home message. Once in a while—and I hate to admit this—an echocardiogram is just not enough. Had we done a transesophageal echo, we would not have seen anything, and had we done a study with agitated saline, it would have been normal and we would have still been looking at each other asking, what should we do next? Unusual case, I thought it was worth showing. I hope you liked it. This is Ron Wharton from Montefiore Medical Center for on Medscape Cardiology. Thanks for tuning in.

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