Trauma-Induced Coronary Artery Dissection

Abstract: Coronary artery dissection occurs when the intima and media layers of the coronary artery separate from each other. Spontaneous coronary artery dissection is a rare event; through 2004, only 150 cases had been reported.1 We report the case of a 22-year-old male with a dissected right coronary artery following a motor vehicle collision while riding his bicycle, and the steps taken to repair the dissection.

Case presentation

A 22-year-old male was riding his bicycle when a motor vehicle struck him and fled the scene. The patient was thrown forward and his chest struck the bicycle handlebars. Emergency Medical Services (EMS) transported the patient to the local trauma center for emergency treatment. Upon arrival, the following injuries were diagnosed:  

• Mild traumatic brain injury;
• Scalp laceration;
• Rib fracture;
• Bilateral pulmonary contusions;
• Respiratory failure, requiring the patient to be placed on a ventilator. 

The patient’s history and physical revealed: 

• Smoking, one pack per day;
• Mild alcohol consumption;
• No drug abuse;
• No hypertension;
• No diabetes;
• Family history was negative for heart disease, diabetes, or hypertension. 

Blood work was normal upon admission and the admitting EKG exhibited normal sinus rhythm. Since the patient complained of chest pain, an echocardiogram was performed. The echo showed no pericardial effusion, but global left ventricular hypokinesis was present.  

Following treatment for his injuries, which included being intubated, the patient was still complaining of chest pain. His troponin levels were shown to be elevated. By this time, the patient had been stabilized and extubated for his transport to a hospital that had percutaneous coronary intervention (PCI) capabilities for a cardiac catheterization and possible angioplasty. Upon arrival at our facility, the patient was brought to the cardiac catheterization lab for a left heart catheterization procedure. 

Procedure

A 6 French FR4 diagnostic catheter (Boston Scientific) was used to access the right coronary artery (RCA). Opening aortic pressure (AO) was 115/68 (90). After cannulating the artery, contrast was injected, and the angiogram showed a lesion originating in the ostium of the RCA and going past the right ventricular (RV) branch (Figure 1). The lesion appeared to have two dissections, one near the ostium and the other distal to the RV branch. In addition, due to its hazy appearance, it was thought there might be some fresh thrombus in the vessel (Figure 2). A 6 French FL4 diagnostic catheter (Boston Scientific) was used to access the left coronary artery (LCA). After cannulating the artery, contrast was injected, and the LCA appeared normal without any evidence of coronary artery disease (Figure 3). A 6 French angled pigtail (Boston Scientific) was then inserted into the left ventricle (LV) to measure pressure and perform an angiogram. LV pressure was 114/1 with a LV end diastolic pressure (LVEDP) of 10. A LV angiogram was performed in the right anterior oblique (RAO) projection. Ejection fraction was verified at about 25% and the inferior wall of the LV showed kinesis/hypokinesis. The pigtail catheter was pulled back across the aortic valve and no pressure gradient was found.  

At this point, the cardiologist decided to do intravascular ultrasound (IVUS) of the RCA in order to determine whether there was a dissection at the ostial and distal lesions, and to determine the morphology of the plaque burden. Bivalirudin (Angiomax, The Medicines Company) was used as the anticoagulant for the procedure. 

The RCA had a superior take-off, making cannulating the ostium difficult. In case greater support might be needed, it was decided to use an 8 French system. The 6 French sheath was exchanged for an 8 French sheath and an 8 French FR4 guide (Boston Scientific) was used to cannulate the RCA. An AllStar (Abbott Vascular) .014” wire was advanced, but was unable to cross the proximal lesion and dissection, due to poor guide support. The physician attempted to place multiple catheters, and finally a 7 French AR1 guide (Boston Scientific) was successful in cannulating the RCA. This catheter provided the back-up and support needed. A Balance Middle Weight (BMW) .014” wire (Abbott Vascular) was then inserted and upon entering the RCA, the wire repeatedly selected the RV branch. After several attempts to cross the lesion without success, the cardiologist left the BMW wire in the RV branch. The cardiologist decided to use a Balanced Heavy Weight (BHW) (Abbott Vascular) .014” wire as a second wire. The BHW was then inserted and was successful in crossing the proximal and mid lesions. The wire was then advanced to the distal RCA. At this time, an Atlantis Pro IVUS catheter (Boston Scientific) was inserted over the BHW wire and advanced distal to the RCA lesions. The IVUS catheter was connected to the iCross IVUS equipment and an ultrasound of the RCA was performed. Using the IVUS sled, the IVUS transducer was pulled back through the lesion and into the guide catheter, showing significant narrowing in the artery (Figure 4). IVUS confirmed the presence of a large hematoma in the mid and proximal RCA that was compromising flow. The false lumen gave the appearance of a thrombosed dissection. This dissection was severely compressing the true lumen. It was believed that this damage was the result of the patient striking the handlebars. 

A 3.0mm x 15mm Voyager (Abbott Vascular) balloon was inserted over the BHW wire down to the mid RCA and three inflations were performed. The pre-dilatation balloon was removed and a 3.0mm x 20mm Vision (Abbott Vascular) bare metal stent was advanced down the BHW wire and was placed across the mid RCA dissections. The stent was deployed at 14 atmospheres (atms) for 40 seconds. The stent delivery system was removed and a 2.5mm x 20mm NC Voyager balloon was advanced over the BHW wire. The balloon was used to post dilate the stent and was inflated to 14 atms for 40 seconds. After removing the balloon, the angiogram revealed that the mid RCA stenosis went from 90% to 10%, with no distal dissections. At this time, the BMW wire was removed from the RV branch. A 3.5mm x 28mm Vision bare metal stent was used to cover the area from ostium to the first stent. The stent was advanced over the BHW wire, placed across the proximal dissections, and deployed at 14 atms for 40 seconds. The stent deployment system was removed and a 4.0mm x 15mm NC Voyager balloon was advanced over the BHW wire to the mid stented segments. Three inflations were performed at 14 atms for 40 seconds each. The balloon was removed and the subsequent angiograms revealed that the stenosis for each lesion went from 90% to 0%. The stent did extend back to the ostium of the RCA and none of the side branches were compromised (Figure 5). Bare metal stents were used since it was not known at the time of the catheterization if the patient would require additional surgeries due to the accident. An IVUS catheter was again inserted to ensure the stents were opposed to the arterial wall. The stent struts were fully opposed to the vessel wall (Figure 6). In addition, IVUS revealed that the false lumen was compressed, with minimal residual false lumen thrombus present in either lesion. The IVUS catheter, BHW wire, and 7 French AR1 guide catheter were all removed. The sheath was removed and hemostasis was achieved using an Angio-Seal vascular closure device (St. Jude Medical). The bivalirudin infusion was discontinued, and 600mg clopidogrel and 325 mg of aspirin were given by mouth. 

Discussion

Kerwin et al define spontaneous coronary artery dissection (SCAD) as the non-iatrogenic, clinical occurrence of acute separation of the arterial media from the intima by hemorrhage, and note that impingement of the false lumen into the true lumen can cause myocardial ischemia or infarction.² In women, the left anterior descending or left main artery is most commonly involved, while in men, the right coronary artery is most commonly affected.² High-impact injuries from motor vehicle accidents have been known to cause SCAD.² However, Kerwin et al report the first known case resulting from a low-impact injury.² SCAD that did not involve a motor vehicle accident was reported in Japan in 1998, when Kawahito et al reported SCAD occurring after a patient was struck in the chest by a horse.³ The SCAD reported in our case was caused by a trauma, but it is difficult to say whether it would be classified as a high-impact injury, low-impact injury, or something in between.

SCAD is a life-threatening event that can result in death or in damage to the myocardium because of reduced blood flow. It is imperative that the SCAD patient be identified quickly and transferred to a facility with PCI capabilities as soon as possible, in order to save myocardium and optimize quality of life.  

The authors can be contacted via Raymond Lenius, MS, RCIS, at raymond.lenius@edison.edu.

References

1. Juszczyk M, Marnejon T, Hoffman DA. Spontaneous coronary artery dissection postpartum. J Invasive Cardiol. 2004 Sep;16(9):524-526.
2. Kerwin TC, Ruggie N, Klein LW. Spontaneous coronary artery dissection following low-intensity blunt chest trauma: a case report and review of current treatment options. J Invasive Cardiol. 2002 Nov;14(11):679-681.
3. Kawahito K, Hasegawa T, Misawa Y, Fuse K. Right coronary artery dissection and acute infarction due to blunt trauma: report of a case. Surg Today. 1998;28(9):971-973.