Vascular Rupture Caused by a Molding Balloon during Endovascular Aneurysm Repair: Case Report

Since the report of the first endovascular repair of an abdominal aortic aneurysm (AAA) by Parodi et al. in 1991, endovascular aneurysm repair (EVAR) has been accepted as an alternative to traditional open surgery in selected patients (1, 2, 3). Despite the minimally invasiveness of this treatment, there are several complications that may occur during or after EVAR. Complications include endoleak, graft thrombosis, graft kinking and migration, aortic dissection, distal embolism, or iatrogenic injury to the access artery (rupture, dissection, and false aneurysm) (1, 2, 3, 4, 5, 6, 7, 8).

However, there are few reports on the vascular rupture caused by a molding balloon during EVAR (8, 9). We report two cases of infrarenal AAA complicated by procedure-related aortic or iliac artery rupture by the molding balloon during EVAR.

Several early complications of EVAR including endoleak, endograft limb obstruction, local vascular complications (groin hematoma, femoral artery injury, iliac artery rupture), and AAA rupture have been reported. Among them, the most common vascular complications during EVAR are iliac artery injury caused by high degree of iliac artery stenosis, tortuosity, and/or calcification (1, 7, 8). However, aortic or iliac artery rupture by a molding balloon dilatation as our cases is a rare complication. Thirteen Intra-operative aortic ruptures were identified from 270 EVAR patients. In four (1.4%, 4/270) of these patients, aortic rupture occurred from balloon dilatation of the proximal aortic neck. Aortic ruptures were managed by open repair, like our case 2 (9). Eleven intra-operative iliac ruptures were identified from 369 EVAR patients. Among them, one case of iliac rupture occurred after balloon dilatation of the iliac limb. This complication was managed by the extension of another iliac limb, as in our case 1 (8).

Because aortic rupture by molding balloon dilatation occurred at the proximal neck of the AAA, endovascular management by extension of another endograft was not possible and all reported cases were managed by open repair (9). In our case 2, because the ruptured site was just below the left renal artery, endovascular management was not considered as a good option. For the control of an aortic rupture, we immediately reinserted the molding balloon and inflated at the level of infrarenal aorta to seal off the ruptured aorta. No more extravasation of contrast medium and patent of both renal arteries were confirmed by angiography via 5 Fr. A pigtail catheter was inserted through the contralateral limb. After angiography, a pigtail catheter was removed and the molding balloon was securely sutured at the right groin to prevent migration. Emergency surgery was performed with occlusion of the aorta with a balloon catheter and the patient's postoperative course was uncomplicated. In patients with iliac artery rupture and hemodynamic compromise, the endovascular aortic occlusion balloon was introduced to stop the bleeding. After balloon occlusion, a limb of the endograft was deployed to repair the ruptured artery in most reported cases (8). In our case 1, for the treatment of unexpected right CIA rupture with stable vital sign, we performed occlusion of the right IIA with coils to prevent type II endoleak, followed by extension of additional graft limb to the EIA. We could finish the procedure after confirming no more contrast leakage from the right CIA on a completion angiogram.

Balloon catheters have two principal applications in peripheral endovascular procedures. Therapeutic or angioplasty ballooning is the forceful inflation of a balloon to dilate stenotic/occlusive lesions in a vessel. In contrast, molding or occlusion ballooning is a less forceful balloon inflation to ensure endograft expansion, placement, and fixation. This is done using larger compliant balloons and a more gentle inflation. These balloons are also used to stop blood flow in medium or large vessels as needed in certain vascular procedures. The law of Laplace states that the force or tension (T) exerted on the wall of the inflated balloon is directly proportional to the pressure (P) within the balloon and the radius of the balloon (T = P × R). Therefore, larger balloons will require less pressure than smaller balloons to generate a substantial dilating force. Similarly, large vessels such as the abdominal aorta or the common iliac arteries require less pressure to dilate and rupture. The Coda Balloon is very useful in endograft molding and aortic occlusion. According to the User's manual, this balloon is composed of a compliant polyurethane material, which facilitates the rapid inflation and deflation, which is advantageous when occluding the aorta. However, a manual recommended slow inflation of the balloon is recommended to prevent vascular rupture. In our cases, we observed a sudden abrupt increase of the diameter of the endograft during balloon inflation, because we inflated the balloon rapidly. Though there has been no detailed description of the cause of vascular rupture during balloon inflation, we think that gentle slow inflation of the balloon is important to prevent vascular rupture (9, 10, 11).

In conclusion, full graft expansion with a molding balloon is of great importance during EVAR because full graft expansion will minimize the chance of endoleak, and residual graft stenosis is the primary etiologic factor of graft limb thrombosis. However, careful attention must be paid during inflation of the molding balloon to prevent vascular rupture as in our cases.