Successful Treatment in a Case of Acute Aortic Dissection Complicated with Acute Myocardial Infarction Due to Occlusion of the L

Recently, the surgical results of acute aortic dissection (Stanford type A) have improved. However, the treatment of cases complicated with severe organ ischemia, especially myocardial ischemia, is very difficult. When the aortic dissection extends to the coronary artery, catastrophic changes in the hemodynamic state occur; as a result, it is often difficult to save the patient’s life in such cases.1 Most of the cases in which a fatal outcome is avoided are successful emergency operation cases or right coronary myocardial infarction cases.2–6 We reported a case successfully treated by percutaneous coronary intervention (PCI) in which an acute aortic dissection was complicated with acute myocardial infarction (AMI) due to occlusion of the left main coronary artery (LMCA). Case Report. A 67-year-old man was admitted to our hospital with sudden severe chest pain after the diagnosis of ischemic heart disease at another hospital on December 18, 2001. On arrival, his consciousness was clear. Blood pressure was 60 mmHg (palpitation) and pulse rate was 94 beats per minute and regular. The wet rale was loud over both lung fields. The chest X-ray film showed pulmonary congestion of both lung fields and no enlargement of mediastinal shadow. The electrocardiography (ECG) taken at the other hospital showed ST-segment elevation in leads aVL and V1–5, and depression in leads II, III and aVF. The ECG findings obtained at the time of admission were sinus tachycardia and complete right bundle branch block. He was diagnosed with AMI based on the general symptoms and ECG findings. Emergency coronary angiography showed 99% stenosis of the LMCA (Figure 1A). Because the hemodynamic state was unstable, emergent PCI on the LMCA was performed. Accordingly, PCI was started by insertion of an intra-aortic balloon pump (IABP) from the left femoral artery. A 7 French (Fr), Vista Brite Tip, JL 4.5 guide catheter (Cordis Corporation, Miami Lakes, Florida) was used and a Balance Middle Weight guidewire (Guidant Corporation, Temecula, California) was passed from the LMCA to the left anterior descending (LAD) coronary artery. As occlusion by thrombus was considered, we attempted to use a Rescue™ aspiration catheter (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota) to aspire the thrombus. However, a defect in contrast density did not show any improvement and the coronary flow of the LAD became slower. Accordingly, the case was assumed to be indicated for stenting and a 4.0 x 18 mm Bx Velocity stent (Cordis Corporation) was implanted (Figure 1B). The defect in the LMCA disappeared after stent implantation (Figure 1C). Although the hemodynamic state remained stable after PCI, a decrease in urine volume and progress of renal dysfunction were noted. We suspected that the IAPB caused the renal flow disorder, and the IAPB was therefore removed the next day. However, the renal dysfunction progressed and the case became further complicated with obstruction of the intestines. Suspecting ischemia in the abdominal vessel, computed tomography (CT) was performed 4 days after PCI. The result showed the aortic dissection from the ascending aorta to the abdominal aorta (Figure 2). The ascending aorta was enlarged to a size of about 47 mm and the left kidney was not contrast-enhanced among the abdominal organs. Considering the general condition, left ventricular dysfunction and renal dysfunction, an emergency operation was judged too difficult and conservative treatment was continued. Due to aggravation of heart failure at 7 days post-PCI, respiratory control was started with a respirator. According to transesophageal echocardiography, the retrograde dissection of the ascending aorta extended the sinus of Valsalva and was found to compress the left main coronary ostium (Figure 3). Coronary flow to the left coronary artery was sufficiently maintained by stent implantation (Figure 4). CT at 30 days post-PCI showed the diameter of the ascending aorta increased to approximately 54 mm. In April 2002, the patient was hospitalized again for the treatment of cardiac shock, and died suddenly on May 5, 2002. Discussion. Generally, the incidence of aortic dissection complicated with MI is about 1–2%.7–9 Cases have been reported on acute myocardial infarction in the right coronary artery, but rarely in the LMCA. Moreover, rapid aggravation of the hemodynamic state makes it difficult to save the life of the patient. Emergency operation seemed to be the successful treatment for saving the patient’s life in most of the cases.10,11 In this case, judging from the symptoms, hemodynamic state and changes in the electrocardiogram, we strongly suspected acute myocardial infarction. Considering that the patient had undergone aortic valve replacement, occlusion by thrombus was also conceivable. Transthoracic echocardiography before PCI did not confirm aortic dissection of the ascending aorta, despite a decrease in the left ventricular wall motion, nor was any enlargement of the superior mediastinum found on chest X-ray. Based on the above, the patient was judged to have acute myocardial infarction of the LMCA and PCI was performed. There was no particular problem with insertion of the guide catheter into the left coronary artery. No resistance was observed in passing the stent into the LMCA. The stent was easily dilated at 10 atmospheres. Coronary angiogram did not show any findings of external pressure. Consequently, stent implantation in the LMCA stabilized the hemodynamic state and succeeded in saving the life of the patient. Considering the general condition, left ventricular dysfunction and renal dysfunction, an operation was judged too difficult. The following are possible mechanisms leading to acute myocardial infarction: 1) the ostium of the coronary artery is compressed by hematoma; and 2) the dissection enters the ostium of the coronary artery. Cardiac echocardiography, CT, etc., are useful in making the diagnosis. However, it was not possible to fully grasp the positional relationship between the dissection and the ostium of the coronary artery with the CT findings. The dissection compressing the ostium of the left coronary artery was found using transesophageal echocardiography. Three-dimensional CT showed that an initial flap was present immediately above the sinus of Valsalva, while the true lumen and false lumen were stained almost identically by angiography. Assuming that the blood flow was equivalent in the true lumen and false lumen, the pressure on the dissection lumen was also considered equivalent. Based on this assumption, it was considered that about 80–90 mmHg pressure was externally pressed on the stent in the LMCA. It was reported that the BX Velocity stent could resist external pressures up to about 1,500 mmHg (28.7 psi) without deformation. If the BX Velocity stent could achieve round inflation in the LMCA while adhered to the vascular wall, the stent was not expected to be deformed or occluded by external pressure in this case. A further problem in this case was the continuation of anticoagulation treatment. To prevent thrombus in the mechanical valve and occlusion of the stent, warfarin and aspirin were administered to this patient. However, the false lumen was not closed by thrombus because of anticoagulation treatment. As a result, there is a risk of enlargement of the aortic dissection. There have been a few reports of onset of cardiac tamponade due to anticoagulation treatment.12,13 CT indicated enlargement of the diameter of the ascending aorta in a short period of time, suggesting the necessity of surgical treatment in the near future. Conclusion. We reported a case successfully treated by percutaneous coronary intervention in which acute aortic dissection was complicated with acute myocardial infarction due to occlusion of the LMCA. Acute myocardial infarction of the LMCA complicated by acute aortic dissection rarely occurs. Due to rapid aggravation of the hemodynamic state, emergency operation is not possible in most cases. Successful implantation of the stent in the LMCA contributed to save the patient’s life.

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