PMC5447279_01
Transthoracic and transesophageal echocardiographic findings. (a) Pulse-wave Doppler at the LVOT showing a peak velocity of 3.94 m/s and gradient 62 mmHg. The waveform contour is dagger-shaped. (b) Strain-phase Valsalva results in an increase in peak velocity to 4.56 m/s with gradient 83 mmHg. (c) Apical view at end-diastole showing no significant LVOT narrowing. The septal wall shows moderately increased thickness measured at 1.4 cm. (d) Apical view during systolic phase showing mitral-septal contact (white arrow) consistent with SAM. (e) Color Doppler showing severe, posteriorly directed mitral regurgitation (dashed arrow) into a moderately enlarged left atrial cavity and significant turbulence across the LVOT (solid arrow). (f) Transgastric short-axis view at the level of the mitral valve during systolic phase, showing a large echodensity attached to lateral scallop of the anterior mitral leaflet (arrowheads).
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Pulse-wave Doppler of the LVOT revealed a late-peaking "dagger-shaped" systolic jet with a peak velocity of 3.94 m/s and gradient of 62 mmHg that, respectively, increased to 4.56 m/s and 83 mmHg with Valsalva maneuver (Figures 1(a) and 1(b)). A transesophageal echocardiogram more clearly pointed out the presence of systolic anterior motion (SAM) of the anterior mitral valve leaflet (Figures 1(c) and 1(d)), but there was also a thicker subvalvular structure attached to the ventricular surface of the anterior mitral leaflet which was noted as not typical of chordae tendineae. The anterior mitral valve leaflet appeared redundant, and color Doppler demonstrated a severe, posteriorly directed mitral regurgitant jet into a moderately enlarged left atrial cavity (Figures 1(e) and 1(f)).
Hemodynamic tracings at cardiac catheterization. (a) Simultaneously measured aortic and LV pressures using a dual lumen pigtail catheter demonstrate an 84 mmHg resting peak-to-peak gradient. The aortic waveform shows a spike-and-dome pattern, and the LV waveform is late-peaking. After premature ventricular contractions are provoked (black arrow), the postextrasystolic beat demonstrates a reduction in aortic pulse pressure with a worsening in peak-to-peak gradient to 160 mmHg (checkered arrow). This finding is consistent with dynamic LVOT obstruction. (b) Pullback tracing with the dual lumen pigtail catheter starting in the mid LV cavity (black arrow) and then being withdrawn to just beneath the aortic valve (checkered arrow) demonstrating normalization of the large gradient. This suggests that the site of obstruction is within the LVOT.
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Using a dual lumen pigtail catheter, simultaneous aortic and LV pressures were recorded showing an 84 mmHg peak-to-peak gradient that increased to 160 mmHg with induction of premature ventricular contractions as well as strain-phase Valsalva (Figure 2(a)). A pullback tracing of the same catheter from the mid LV cavity to just beneath the aortic valve in the LVOT showed normalization of the gradient, corroborating the subvalvular level of obstruction and the lack of aortic valve involvement (Figure 2(b)).
Gross pathology findings. (a) Specimen excised during surgery showing a hypertrophied anterolateral LV papillary muscle attached directly to the anterior mitral leaflet edge with minimal chordae present (white arrow). The anterior leaflet appears myxomatous. (b) In situ view of anomalous anterior papillary muscle (asterisk) insertion directly into anterior mitral leaflet (black arrow) which is more anteriorly displaced and extending across the LVOT.
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After opening the left atrium, the mitral valve leaflets appeared thickened and myxomatous, but notably, the anterolateral papillary muscle was anteriorly displaced and inserted directly into the A1 scallop of the anterior mitral leaflet with minimal chordae tendineae attachments (Figures 3(a) and 3(b)).