A different approach to multilayer flow modulator implantation in aortic aneurysm

Introduction

Thoracoabdominal aortic aneurysms are commonly observed clinical conditions; if remain untreated, the aneurysms might grow larger and cause death due to rupture (1, 2). Since the early 1950s, open surgery approach has been used for the treatment (3). However, with developments in endovascular methods for the last 20 years, percutaneous treatment methods have become an alternative to open surgery. Percutaneous treatment methods have been increasingly used since they are shown to shorten the duration of intensive care and hospitalization and can be applied in patients with other system problems, can reduce blood loss and transfusion needs, and have lower rates of mortality and morbidity (3, 4).

Certain special endovascular systems have been developed for treating complex aneurysms of the major side branches arising from or nearby the aneurysm sac. Fenestrated stent grafts (5), chimney technique and multilayer flow modulator (MFM) are among the best known endovascular systems (6, 7).

Case Report

A 64-year-old male patient presented to our clinic with chest and back pain. His medical history revealed previous treatment for hypertension and diabetes mellitus for the last 10 years. Critical stenosis in the left and right coronary arteries was detected in coronary angiography; contrast computed tomography showed a 7-cm diameter aortic aneurysm starting from the distal of the left subclavian artery and extending to proximal of the celiac trunk (Fig. 1). Two MFMs (Cardiatis, CTMS 40150) were placed in the aneurysm region for endovascular intervention. However, the targeted region could not be reached due to the insufficient flexibility of the transmission system of the stent and/or anatomy of the aortic arch, an observation that was evident with the presence of the proximal end of the stent angled to the aortic axis (Fig. 2). Consequently, the procedure was terminated; the patient underwent open heart surgery 3 days later, and arterial cannulation was performed from the right subclavian artery after sternotomy. Subsequently, aortotomy was performed in the ascending aorta after total circulatory arrest under antegrade cerebral perfusion. The angulation (Fig. 3) of the MFM stent was corrected by manual guidance. Afterward, an MFM stent was implanted aligning from the T4 vertebra level up to the innominate artery distal (Fig. 4-6). Then, the procedure was continued with coronary bypass. The patient was extubated at the 4^th hour after surgery, and no symptoms associated with neurological deficit and/or organ failure were seen. The patient was discharged on the 5^th day after operation (Fig. 7).

Figure 1.

Contrast CT angiography of the aortic aneurysm

Figure 2.

Suboptimal insertion of a multilayer flow modulator placed through the femoral artery

Figure 3.

The appearance of arcus aorta in the aortotomy

Figure 4.

Insertion of the multilayer flow modulator through the aortotomy

Figure 5.

The opening of the multilayer flow modulator

Figure 6.

Implantation of the multilayer flow modulator

Figure 7.

Contrast CT angiography after the operation

Discussion

Recently, many new approaches have been developed for the treatment of thoracoabdominal aortic aneurysms; among them, endovascular systems have been increasingly used due to lower morbidity and mortality (3, 4). Although the femoral artery (80%) is most commonly used for intervention, iliac, subclavian, and axillary arteries can also be used as alternatives. The diameter of vessel, amount of calcification, and severity of tortuosity are the most important factors for determining the intervention area. The vessel diameter should be at least ≥7 mm for 20-22-F introducers. The presence of heavy calcification increases the risk of rupture and dissection of the aorta. The amount of calcification not only leads to a decrease in the vessel diameter but also restricts its expandability. Extreme tortuosity in the vessel is another problem that complicates percutaneous intervention. In the presence of tortuosity, straightening of the vessel can be achieved using strong firm wires. The use of two or three wires can efficiently facilitate straightening of extreme tortuosity in the vessel (8).

When femoral arteries are not suitable for endovascular intervention due to the presence of stenosis and/or calcification, iliac arteries are most commonly used (15%). There are at least a few cases wherein 8-10 mm conduit grafts were anastomosed to iliac arteries. The use of conduit graft facilitates the feasibility of the procedure and significantly decreases the incidence of complication rates (9, 10).

In case no peripheral artery is suitable for the intervention and both mortality and morbidity of the surgical intervention for an aneurysm are high, the endovascular operation can be performed through the ascending aorta after sternotomy. If the patient has an additional pathology that requires open heart surgery, as in our case, one may consider intervening in the extracorporeal circulation and to cut the ascending aorta to perform the surgery. If there is no requirement for an open heart surgery, we believe that the operation can be performed by following these steps: performing an upper ministernotomy without intervening in the extracorporeal circulation, followed by an anastomosis of an 8-10 mm diameter conduit graft to be used as the entry point.

Conclusion

The ascending aorta can be used as an intervention area in the treatment of aortic aneurysms when the endovascular operation cannot be performed due to the difficulty of intervention area or implantation difficulty during operation.