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).

FIGURE 35-4 There is continued narrowing noted of the distal left main after stenting of the ramus intermedius and despite the generous administration of intracoronary nitroglycerin.

In order to determine both the mechanism and extent of the distal left main stem luminal narrowing, intravascular ultrasound was performed. The ultrasound catheter was pulled back from the ramus to the ostium of the left main (Video 35-5). At the distal end of the left main, an intramural hematoma was clearly apparent (Figure 35-5). More proximally, discrete intimal flaps were present and occupied almost 50% of the left main lumen (Figures 35-6, 35-7). Based on the ultrasound images, the operator decided to stent the injured segment of the left main stem with a 4.0 mm diameter by 12 mm long paclitaxel-eluting stent, thus restoring the vessel to a normal angiographic appearance (Figure 35-8 and Video 35-6). Repeat intravascular ultrasound assessment confirmed excellent stent apposition and wide luminal patency of the left main stem.

FIGURE 35-5 This is a representative intravascular ultrasound image of the distal left main, demonstrating an intramural hematoma and an intimal tear (arrow).

FIGURE 35-6 An intimal flap is prominent in this intravascular ultrasound image of the left main coronary artery (arrow).

FIGURE 35-7 Another representative image of the prominent intimal flap in the left main coronary artery (arrow).

FIGURE 35-8 Final angiographic appearance of the left coronary artery following stenting of the left main stem.

Postprocedural course

Following the procedure, she remained free of chest pain. She was admitted to the coronary care unit for observation, and remained pain-free overnight. After ambulating without difficulty, she was discharged the next day on metoprolol, simvastatin, 325 mg of aspirin, and 75 mg of clopidogrel indefinitely. At follow-up 6 weeks later, she felt well, remained tobacco-free, and was without recurrent chest pain.

Discussion

This case validates the wisdom offered by experienced interventionalists that “there is no such thing as an easy angioplasty”, but also emphasizes the importance of careful vigilance and scrutiny of the angiogram. The lesion in the ramus intermedius offered no particular challenges. The first clue that this case would not turn out to be “easy” occurred when the operator encountered unexpected difficulty passing the guidewire out of the tip of the guide catheter. Although remedied by repositioning the guide catheter and wire, that event likely heightened the operator’s awareness for the potential of a left main injury, focusing his attention on the subtle angiographic finding seen in the distal left main that was subsequently found to represent a dissection and intramural hematoma of the left main, with potentially serious consequences if untreated.

Guide-related injuries of the left main stem or proximal right coronary artery during percutaneous intervention are uncommon and usually caused by large-bore guide catheters with aggressive curves, lack of coaxial engagement, deep engagement in the coronary ostium to provide backup, and presence of underlying atherosclerosis.^1,2 Although possible, in this case, it does not appear that the guide catheter caused the intimal injury, as there was no evidence of a dissection by angiography. The major cause of this injury was likely due to the guidewire. The tip probably penetrated the intima and entered the subintimal space, creating an intimal flap and an intramural hematoma.

The subtle luminal narrowing of a previously normal segment provided the most important clue to the presence of this complication. Usually, dissections create a visible flap and retention of contrast. In this case, these features were absent and only luminal narrowing was seen. Such a finding is either due to spasm or a dissection with an intramural hematoma. Failure to resolve with nitroglycerin convinced the operator that something more devious than spasm was at hand. Intravascular ultrasound was indispensible in this case. In addition to confirming the diagnosis, and demonstrating the intramural hematoma, the ultrasound images defined the extent of the injury and guided the stent repair.

Treatment of a guide- or wire-related injury depends on the extent of the injury and the presence of luminal compromise. Small tears without contrast retention or luminal compromise can be treated conservatively. Large dissections retaining contrast or causing luminal obstruction or intramural hematomas impinging upon the lumen need definite therapy with either stents or surgery.