Catheter-Induced Left Main Dissection Incidence, Predisposition and Therapeutic Strategies Experience from Two Sides of the Hemi

Case report 1. A 68-year-old caucasian male presented for a coronary angiography one month after an acute anterior myocardial infarction. It revealed total occlusion of the left anterior descending (LAD) artery. A decision was taken to attempt to open the totally occluded LAD, owing to the frequent occurrence of post-MI angina. The left main coronary artery take-off was normal, and was selectively cannulated with a 7 Fr Judkin’s Left-4 guiding catheter (Cordis J&J, Miami, Florida). The patient was given 10,000 units of heparin intravenously, and his activated clotting time 15 minutes later was 250 seconds. The LAD was negotiated with a ChoICE^®-PT wire (Boston Scientific-Scimed, Maple Grove, Minnesota). After securing the wire in a fairly distal position, multiple balloon inflations were performed in the LAD, from distal to proximal. During the procedure, the guiding catheter was inadvertently deep seated into the left main coronary artery, while the angioplasty balloon was being withdrawn into the guiding catheter. The proximal LAD and the distal left main coronary arteries demonstrated a spiral dissection, as shown in Figure 1A. In a repeat angiogram minutes later, the dissection had progressed retrogradely, as to involve the aortic root (Figure 1B). The operator attempted to seal the left main coronary dissection using a 3.5 x 18 mm S7 stent (Medtronic AVE, Minneapolis, Minnesota; Figure 1C), but the patient developed severe chest pain, acute pulmonary edema, profound hypotension, and ventricular fibrillation, which was successfully reversed. Emergent bypass surgery was performed, along with aortic repair and reinforcement using Teflon felt strips to obliterate the proximal false lumen, and the patient had an uncomplicated post-operative course. The surgical specimen is shown in Figure 1D. Six months after the procedure, the patient is clinically well and asymptomatic. Case report 2. A 66-year-old white male with hypertension, well-controlled on medical treatment, was evaluated prior to an abdominal aortic aneurysm (AAA) surgical repair. A pre-operative coronary angiogram, using a 4 Fr diagnostic Judkin’s Left 4 catheter, resulted in the angiographic picture seen in Figure 2. A type-A dissection (NHLB-I classification) was observed in the distal left main and the very proximal LAD. Otherwise, the patient had angiographically normal coronary arteries. The patient continued to be free of chest pain and was treated with high doses of beta-blockers. He was discharged after 2 days of coronary care unit (CCU) observation, remained stable and asymptomatic, and underwent elective AAA repair one month later. Case report 3. A 55-year-old female with chronic stable angina and a positive thallium scan presented for elective stenting of the proximal LAD. After successful stenting of the proximal LAD, and while the post-deployment balloon was being positioned inside the stent, contrast injection revealed a type-C dissection (NHLB-I classification) in the left main coronary artery (Figure 3). The patient developed moderately severe chest pain, but was hemodynamically stable. She underwent coronary bypass surgery after a few hours of close observation in the CCU, during which she developed hemodynamic instability. Case report 4. A 63-year-old male presented with an acute anterior MI 2 days following abdominal surgery. He underwent coronary angiography which revealed a normal short left main and a totally occluded LAD proximally (Figure 4A). During coronary angiography in subsequent projections, a type B left main dissection was visible (Figure 4B). The patient developed recurrent shock-resistent ventricular fibrillation (VF), and died during the procedure. Case report 5. A 43-year-old African-American male with a history of type-II diabetes mellitus, coronary artery disease and previous stenting of the proximal LAD, presented with in-stent restenosis of the proximal LAD. During an angioplasty procedure, and shortly before the intracoronary bracytherapy catheter was introduced, a type-B dissection was seen in the left main (Figure 5). The patient remained asymptomatic and hemodynamically stable, but underwent coronary bypass surgery on the same day. Discussion. We report five cases of iatrogenic left main coronary artery dissection. We describe the possible difference in the spectrum of this complication from a “self-limiting” tear, to an extensive left main and aortic dissection with cardiogenic shock. Four cases were reported in Ain Shams Hospital over a period of 5 years and 2,700 coronary angioplasty procedures (0.2%). One case was reported in the Memmorial Hermann cath lab over the past couple of years (2,800 coronary angioplasty procedures), with an incidence of 0.035%. Left main dissections were identified through a systematic review of the angiograms at both institutions. The diagnoses were then confirmed through a review of the patients’ medical charts. Catheter-induced coronary artery dissection is a rare but a well-recognized, life-threatening complication of coronary angiography and angioplasty.¹ Few case reports of catheter-induced coronary artery dissections have been published, most of which were right coronary artery dissections, having occurred during diagnostic angiography, elective angioplasty or emergent angioplasty for acute myocardial infarction (AMI).² Catheter-induced left main dissection with and without aortic root extension is even more rare, with very few reports in the literature. Mechanisms. The exact mechanism of left main dissection retrogradely involving the aortic root remains unclear. However, it appears that the entry point originates within the coronary artery dissection and subsequently leads to progressive retrograde dispersion of the subintimal space into the aortic root. Such dispersion could result from vigorous hand injection of contrast medium, subintimal passage of the guidewire, and/or inadvertent handling of the guiding catheter.³ Susceptibility to the development of intimal tears and propagation of the hematoma may be related to an underlying structural weakness of the media.² Predisposing factors include hypertension, Marfan syndrome, congenitally unicuspid and bicuspid aortic valves, and cystic medial necrosis.⁴ Extensive atherosclerosis has also been suggested as a risk factor for dissection.⁵ Plaque ulceration may serve as an entry point for the pulsatile flow of blood while atherosclerosis has been postulated to weaken the media through impaired nutrition.⁵ In a previously published report² exclusively on right coronary trauma, left Amplatz guiding catheters were involved in a disproportionate number of catheter-induced right cornary dissections. Although Amplatz catheters were used in their cases to provide better support, the authors suggested that these catheters may be an associated risk for dissection (even when used for left coronary cannulation) and advised increased caution, particularly in the acute setting.²Left main dissection: Is it a preventable complication? Earlier reports have suggested that “the best safeguard against left main dissection is a careful technique.”⁶ However, this conclusion cannot be generalized. Careful interventional technique will most likely protect against a certain percentage of such cases, but will not eliminate dissections entirely. Highly experienced interventional cardiologists have reported iatrogenic dissections at an incidence rate of 0.02%.² Case report 5 reported here was the only case reported among 2,800 angioplasty procedures in the last couple of years at that hospital, with an incidence of 0.035%. On the other hand, in the other four cases we report here, a less vigilant technique was to blame for the occurrence of these iatrogenic dissections. Cautious techniques that can minimize the occurrence of iatrogenic dissection include: 1) The importance of avoiding deep engagement of guiding catheters (especially 7 Fr and 8 Fr sizes), and maintaining a steady tension on the guiding catheter while the angioplasty balloon is withdrawn. Although there are no published data to support this recommendation, it has been part of our routine to abide by this technique. Case 1 reinforces the possible consequence(s) of continued deep engagement of a guiding catheter; 2) The importance of prompt and timely recognition of this complication to prevent both retrograde and antegrade extension (case 1); 3) The importance of minimizing futile efforts to “halt” the progression of the dissection. Once retrograde extension of the left main dissection has involved 40 mm or more of the aortic root,⁸ especially in the presence of hemodynamic instability (as in case 1), it is imperative to call the surgeons to prevent more deterioration of the patient’s hemodynamic state; 4) The importance of checking pressure before every coronary injection. If a ventricularized pressure waveform is observed, further injections should be halted and the catheter manipulated until an arterial pressure waveform is observed. Management. The strategy for managing isolated left main dissection can be conservative, percutaneous intervention, or bypass surgery.^8–11 Watchful waiting, suggested by Alfonso et al.,⁸ is a reasonable option in the hemodynamically stable patient with a low-grade dissection. The presence of hemodynamic instability is a clear indication for intervention. In the few cases described in the literature to date, percutaneous management, in the form of stenting of the coronary dissection entry point, was reserved for patients with “limited” aortic involvement, whereas aortic involvement of 40 mm or more from the coronary ostium was considered a clear indication for surgical intervention.⁷ Intra-aortic balloon pump (IABP) may serve to stabilize the patient, and has been used as a bridge to surgery in some cases reported in the literature,⁹ but is obviously contraindicated in the presence of concomitant aortic dissection. IABP may also serve as a hemodynamic support measure during percutaneous intervention in such cases when a large amount of myocardium is at risk. It is most likely that the decisions to watchfully wait versus surgery in the patients we report were rational. The first patient had a clear-cut indication for emergent surgery. The second patient was managed conservatively based on the small extent of the dissection. Although it was possible to manage the fifth patient conservatively, the presence of the left main dissection in a young diabetic patient in whom in-stent restenosis of the proximal LAD was not entirely addressed, bypass surgery was an attractive option, especially since it was performed in a “non-emergent” setting. Since the natural history of left main dissections are not well-documented, and largely unknown, an appropriate follow-up of those patients who have survived the catastrophic event of a left main dissection involves a diagnostic coronary angiography within 6 months. This will serve to document healing of the dissection in patients who were managed expectantly, and to demonstrate possible in-stent restenosis in patients who were managed by stenting. In a recent report,¹² aggressive restenosis was demonstrated distal to the site of the stented dissection in the left main, which mandated a bypass surgery. Conclusion. Catheter-induced left main coronary artery dissections are rare, but ominous situations. Retrograde extension into the aortic root often requires emergency, life-saving surgical intervention. Awarness of the problem and its prompt recognition are essential.

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