Case presentation

After presenting to the hospital with a 3-day history of intermittent chest pain and diaphoresis and found to have a non-ST segment elevation myocardial infarction, a healthy 49-year-old woman, with the coronary risk factors of tobacco abuse and dyslipidemia, underwent cardiac catheterization and was found to have a severe stenosis in the ramus intermedius branch (Figures 35-1, 35-2 and Video 35-1). Her other coronary arteries showed no angiographic evidence of significant atherosclerotic disease. She was subsequently referred for percutaneous treatment of the ramus intermedius branch.

FIGURE 35-1 This is a left anterior oblique projection with caudal angulation of the left coronary artery demonstrating the focal severe stenosis of the ramus intermedius (arrow). Note the normal appearance of the distal left main stem.

FIGURE 35-2 This angiogram of the left coronary artery in a right anterior oblique projection with caudal angulation shows the normal appearance of the left main artery and the apparent coaxial position of the guide catheter. The ramus lesion is obscured from view.

Cardiac catheterization

The patient received a 300 mg loading dose of clopidogrel the previous day and was administered 325 mg of aspirin. After receiving a bolus plus an infusion of bivalirudin, the left main coronary artery was engaged with a 6 French JCL 4 guide catheter without difficulty. The operator then attempted to pass a 0.014 inch floppy-tipped guidewire into the ramus intermedius branch but encountered resistance as soon as the wire tip exited the guide catheter. Gentle wire manipulations failed to advance the guidewire beyond the tip of the guide. Although the guide catheter appeared coaxial to the left main stem, the operator withdrew the guide and re-engaged. This time, the guidewire easily advanced into the ramus intermedius. Throughout this period, the patient remained symptom-free.

After passing the wire successfully and predilating the ramus lesion with a 2.0 mm diameter by 12 mm long compliant balloon, the operator happened to note an unexpected narrowing of the distal left main stem and positioned another 0.014 inch floppy-tipped guidewire into the left anterior descending artery (Figure 35-3 and Video 35-2). Several intracoronary boluses of nitroglycerin did not change the appearance of the distal left main narrowing. The physician proceeded with stenting of the ramus lesion using a 2.25 mm diameter by 16 mm long paclitaxel-eluting stent (Figure 35-4 and Videos 35-3, 35-4). The narrowing of the distal left main stem remained unchanged throughout the procedure on the ramus intermedius.

FIGURE 35-3 This angiogram was obtained after balloon angioplasty of the ramus intermedius and revealed an unexpected narrowing of the distal left main coronary artery (arrow).