Misdiagnosis of severe aortic stenosis instead of severe eccentric mitral regurgitation: Possible causes and ways for prevention.

Sir,

Rheumatic mitral regurgitation (MR) is commonly associated with aortic stenosis (AS).[1] During echocardiographic examination, severe MR may lead to underestimation of severity of AS gradient.[2] However, in some cases severe eccentric MR may result in misdiagnosis of AS. We describe a case which was diagnosed preoperatively as severe AS with moderate MR on transthoracic echocardiography (TTE) but was found to be severe eccentric MR with ruptured chordae and normal aortic valve on transesophageal echocardiography (TEE) leading to change in the surgical plan.

A 75-year-old woman (height 148 cm, weight 55 kg), a known asthmatic since 4 years and with history of increasing shortness of breath and recent onset cough (4 days), was referred to our institute with diagnosis of sclerodegenerative severe AS with moderate MR. She had no history of chest pain or swelling of limbs.

Auscultation of her chest revealed systolic murmurs at apex and aortic area radiating to left axilla. TTE done preoperatively suggested sclerodegenerative aortic valve, severe AS (peak gradient 133 mmHg, mean 75 mmHg), concentric left ventricular hypertrophy, moderate MR, moderate tricuspid regurgitation, pulmonary artery hypertension (right ventricular systolic pressure = 45 + right atrial pressure), and normal left ventricular function. Her coronary angiogram showed normal coronary arteries; however, cardiac catheterization for pressure gradient measurement was not done. She was scheduled for aortic valve replacement.

In the operating room, TEE examination after induction of anesthesia in mid-esophageal four-chamber view showed flail posterior mitral leaflets with ruptured chordae [Figure 1a]. Color Doppler showed severe eccentric wall hugging MR jet along the anterior mitral leaflet [Figure 1a]. On mid-esophageal aortic, short-axis view showed well co-apting aortic cusps with sclerodegenerative changes. Mid-esophageal aortic long-axis view showed no turbulence across aortic valve and a severe eccentric MR jet along the direction of aortic flow hugging the anterior wall of Left Atrium [Figure 1a]. Deep transgastric view showed normal gradient across aortic valve (peak 4 mmHg, mean 2 mmHg) [Figure 1a]; however, shift of continuous wave Doppler (CWD) cursor on wall hugging eccentric MR leads to elevation of gradient to peak of 57 mmHg and mean of 41 mmHg [Figure 1b]. To find out what leads to misdiagnosis, TTE was repeated on table which in apical five-chamber view showed an eccentric wall hugging MR jet along the anterior mitral leaflet [Figure 1c], sclerodegenerative thickening of aortic cusps, and high-pressure gradient on application of CWD across aortic valve (peak 94 mmHg and mean 58 mmHg) [Figure 1c]. Wall hugging jet along the anterior left atrial wall was picked up by CWD and was the cause for high gradient leading to misdiagnosis. Parasternal long-axis view showed normal flow pattern. Change in surgical plan was discussed with the patient's family and after written consent mitral valve replacement with prosthetic mitral valve was done. After surgery, TEE showed normal functioning prosthesis. She was discharged from hospital after a week.

Figure 1

(a) Mid-esophageal four-chamber view showing flail posterior mitral leaflet. Mid-esophageal aortic valve long-axis view showing flail posterior mitral leaflet and eccentric wall hugging mitral regurgitation jet impinging on aortic root. (b) Deep transgastric view showing true gradient. Deep transgastric view showing gradient across mitral valve. (c) Transthoracic echocardiography showing apical five-chamber view with eccentric wall hugging mitral regurgitation. Transthoracic echocardiography in apical five-chamber view showing high gradient

Multiple factors may contribute to false diagnosis of severe eccentric MR jet as severe AS.[3] Physical examination may not be able to distinguish between MR and AS due to both causing a systolic murmur.[1] Particularly with rupture chordae tendineae of posterior mitral leaflet, the regurgitant jet is directed anteriorly impinging on the interatrial septum adjacent to the aortic root and causes a systolic murmur that can be easily confused with that of AS.[14] Poor acoustic window in a case with hyperinflated lungs due to obstructive lung disease may lead to inadequate two-dimensional imaging of aortic valve during TTE examination. Excessive reliance on CWD in this situation may be misleading. AS jet and MR jet, both being systolic signals, are directed away from transducer. If electrocardiography (ECG) is not monitored during echocardiography to distinguish timing of the velocity signal with respect to cardiac cycle, differentiations of MR signal from AS may become difficult. Also, gradient exceeding 100 mmHg (peak velocity of 5 m/s) across aortic valve without any feature of myocardial ischemia is very unlikely in a case of AS. However, adherence to basic principles of echocardiocardiography like imaging a structure from multiple windows, looking for mosaic pattern on color Doppler at the site of suspected stenosis, correlating timing of jet with respect to ECG (MR jet onset early in systole, while AS jet start latter in systole), looking for the shape of jet helping differentiate AS from MR jet (AS jet in dynamic obstruction has dagger shape, while MR jet has smooth contour), and avoiding overreliance on CWD may prevent such misdiagnosis.

Finally, one should be very careful to position CW Doppler in a direction avoiding the MR jet in the presence of wall hugging eccentric MR jet.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.