Structural Heart Disease > Cases

Left Main Ostial Dissection resulting in Ostial Narrowing After Direct Cannulation During AVR
- Operator : Seung-Jung Park, MD
Case presentation
A 76-year-old woman was referred to Asan Medical Center (AMC), Seoul, Korea because of increasing exertional dyspnea and palpitation for 2 months. She had atrial fibrillation. Physical examination and echocardiogram revealed severe aortic valve stenosis (aortic valve area: 0.49 cm, transvalvular mean pressure gradient 73 mmHg). Preoperative coronary angiogram was normal. In June 2001, she underwent aortic valve replacement with Carpentier-Edwards mechanical prostheses, 21mm in size. She had undergone operation with antegrade delivery of cold blood cardioplegia and direct cannulation of both coronary ostia. The patient had complete recovery. She was discharged by oral anticoagulant prescription.
Five months later, she admitted to AMC, Seoul, Korea with a 2-day history of increasing severe chest pain and dyspnea on exertion. On admission, blood pressure was 130/70 mmHg and pulse rate 65 beats/min and irregular. Resting electrocardiogram showed ST depression of 2 mm and T-wave inversion in precordial leads, I and aVL. Initial Troponin I and CK-MB were elevated to 8.1 ng/mL (N; 0~1.5 ng/mL) and 35.2 ng/mL (N; 0~5.0 ng/mL), respectively. An echocardiographic study showed good function of the prosthetic valves. Left ventricular ejection fraction was 66% and the apical wall and septum was mildly hypokinetic.
Coronary angiography after aortic valve replacement
1. Repeat coronary angiogram showed tight stenosis at LMCA ostium (Figure 1 and Figure 2). By QCA analysis, reference vessel diameter was measured 4.7 mm with a lesion MLD of 0.4 mm and a lesion length of 5.9 mm (% diameter stenosis= 91 %).

2. LCX and RCA were normal.

Baseline intravascular ultrasound
Left main to LAD was wired with 0.014 F Choice PT wire. IVUS was performed through the wire. IVUS image showed the tight stenosis at LMCA ostium (Figure 3). Lesion EEM CSA (external elastic membrane cross sectional area) was 18.3 mm and lumen CSA was 2.2 mm2. Distal reference EEM CSA was 20.4 mm2 and lumen CSA was 15.5 mm2 (Figure 4).
Insight from IVUS findings, commented by Dr. Gary S. Mintz
I am pretty sure that the IVUS images show neither intimal hyperplasia nor disease progression. I believe that during cannulation of the LM (during AVR) a plaque was "lifted up" - in other words, the cannula created a dissection plane and a false lumen. (Perhaps the surgeon needed a couple of tries to cannulate the LM and injured the LM during one of these tries?) The false lumen increased in size and the dissection flap gradually narrowed the lumen and caused a LM stenosis. If you look at the IVUS beginning at 11:00:15 (Figure 5 and Figure 6) and continuing nearly to the end, there is flow from 10-1 o'clock with a plane of tissue separating this flow from the lumen containing the IVUS catheter. In other words, there are two lumens. I believe that the IVUS catheter is in the true lumen and that the false lumen is in the upper left hand corner. The false lumen appears to end somewhere between 11:00:12 (Figure 7) and 11:00:15 (Figure 5 and Figure 6); it appears to end in a blind pouch. Also, if you look carefully at the pre-AVR CAG, the position of the tip of the diagnostic catheter is probably just distal to the plaque that was lifted up.
Procedure
Because of labile blood pressure during coronary angiography, intraaortic balloon pump was inserted through right femoral altery and counterpulsation was begun at the 1:2 setting. Then, an 8F sheath was inserted through right femoral artery and the left coronary was engaged with a 7F, 4cm curve left Judkins catheter. Left main to LAD was wired with 0.014F Choice PT wire. After pre-dilation with a 4.0 mm x 20 mm Maverick balloon, the LMCA ostium was stented with a 4.5 mm x 8 mm Bx stent with 10 atm to cover only the LMCA ostium (Figure 8). Then, post-dilation to achieve stent optimization was performed upto 16 atm with stent balloon. Final angiogram showed a good result with QCA measurement of LMCA MLD of 5.0 mm (Figure 9). By IVUS image after procedure, final stent area was 17.8 mm2 (Figure 10).
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