Pancreatic Pseudoaneurysm Treatment & Management

Although occasional reports have alluded to the spontaneous thrombosis of some pancreatic pseudoaneurysms, the current consensus is that all of these malformations should be treated to prevent the complication of bleeding. This is based on the fact that the natural history of visceral artery pseudoaneurysms is largely unknown. Treatment options include the following:

• Endovascular coil embolization
• Covered stent placement ^[18]
• Percutaneous injection of an embolizing agent under ultrasonographic (US) guidance
• Open surgical repair

A major controversy is whether transarterial catheter angioembolization should be the definitive approach or whether it should always be followed by surgical intervention, especially if bleeding is located in the tail or body of the pancreas or is associated with a pseudocyst. Some authors have found no rebleeding after seemingly successful angioembolization of the pseudoaneurysm. Other authors have found statistically significant rebleeding rates, which necessitated surgical resection after embolization.

A study ^[19]  of eight patients reviewed the nonsurgical management of pancreatic pseudocysts associated with arterial pseudoaneurysm. Two patients were treated with percutaneous thrombin injection, and six underwent angioembolization. All of these patients underwent subsequent endoscopic transpapillary drainage with complete resolution of pseudocysts in 6 weeks.

An 11-year retrospective study ^[20]  identified 16 patients in whom a pseudocyst had eroded into a major blood vessel, with subsequent development of hemorrhage or false aneurysm. Ten patients underwent operative therapy, whereas six stable patients underwent angioembolization. The surgical morbidity was 62%, and the angioembolization morbidity was 50%. The study concluded by recommending angioembolization as initial therapy for hemodynamically stable patients.

Another major controversy is whether to perform arterial ligation or pancreatic resection on a bleeding pseudoaneurysm. Some authors have strongly advocated resection, because it is technically easier to perform than ligation in an inflammatory milieu. ^[21]  Other authors have reported better outcome after performing proximal and distal arterial ligation and intracystic suture ligation.

A third controversy involves the management of postoperative bleeding, despite adoption of the operative option by more healthcare providers.

Endovascular coil embolization has been used extensively in the treatment of visceral artery pseudoaneurysms. ^{[3, 2, 22]} Angioembolization is considered much less invasive than surgery. The procedure can be completed quickly and is comfortable for the patient. It also allows the performance of surgery under optimal conditions. (See the image below.)

Success rates in the range of 67-100% have been reported for the interventional approach. ^{[2, 17, 23]}  Most authorities agree that embolization is appropriate when bleeding is diffuse or emanating from the pancreatic head, when surgery has been unsuccessful, or when postoperative bleeding occurs.

Failure results from inability to selectively catheterize the bleeding vessel or from misplacement or poor placement of embolization material. In addition to rebleeding, complications of this procedure include rupture of the pseudoaneurysm during embolization, arterial perforation by the catheter, intestinal necrosis, and aortic thrombosis.

Despite some reports of resolution of pseudocysts with embolization alone, little long-term follow-up care is available for patients treated angiographically, particularly for patients who have underlying pathology that predisposes them to recurrent complications.

Nykänen et al assessed the use of transarterial catheter angioembolization combined with therapeutic endoscopy for bleeding pancreatic pseudoaneurysms. ^[24]  In the 58 patients who underwent angioembolization, the rebleeding rate was 15.5%, and the overall success rate was 96.6%. Of the 58, 47 were followed up for their bleeding pseudocysts; 13 (27.1%) experienced spontaneous resolution of their lesions, and 34 underwent attempted endoscopic treatment (32 successfully). Of the 32 patients successfully treated with endoscopy, seven (21.9 %) needed an additional drainage procedure. The overall success rate of nonsurgical management was 91.5%.

Venturini et al retrospectively compared covered stenting (n = 30) with transcatheter embolization (n = 70) in 100 patients who underwent endovascular treatment for visceral artery aneurysm (VAA; n = 51) or visceral artery pseudoaneurysm (VAPA; n = 49). ^[25]  The technical success rates were 97% for covered stenting and 96% for transcatheter embolization; the respective 30-day clinical success rates were 87% and 81.4%.

Percutaneous injection of thrombin into the head of the pancreas for treating pancreatic head pseudoaneurysm has been described. ^[26] Percutaneous US-guided thrombin injection has been successfully used to treat visceral artery pseudoaneurysms. ^{[27, 28, 29]} Suitable anatomic features, such as a narrow neck, are necessary to allow successful intervention without intravascular "leakage" of thrombin with distal embolization. Some advocate balloon inflation across the neck of the pseudoaneurysm to minimize this complication. ^[30]

Percutaneous injection of glue has also been described. ^[31]

Absolute indications for emergency exploratory laparotomy include hemodynamic instability and failure of endovascular techniques to control active hemorrhage.

Basic surgical techniques for controlling hemorrhage from a pancreatic pseudoaneurysm include arterial ligation on both sides of the bleeding sites, pancreatic resection, and multiple intracystic/extracystic ligatures.

Some pseudocyst drainage procedures have been frequently performed concomitantly with the primary hemostatic surgery. Endoscopic drainage is contraindicated. Drainage is an inadequate treatment of a pseudocyst that has bled.

Preparation for surgery

A hemodynamically unstable patient should be managed in an emergency fashion, in much the same manner as a trauma patient. The patient's hemodynamic status and comorbid medical issues dictate the necessity for invasive hemodynamic monitoring.

The first priority is securing the airway, followed by obtaining good peripheral access. As with trauma patients, at least two wide-bore intravenous (IV) lines are preferable. Initial fluids of choice are isotonic crystalloids.

Send a type and cross of the blood to the blood bank while the need for O-negative and type-specific blood transfusion is being assessed. Patients should undergo emergency celiotomy to control the bleeding pseudoaneurysm as soon as possible.

Preoperative studies

If the diagnosis of a ruptured pseudoaneurysm has been seriously entertained and the patient is hemodynamically stable, some studies may be performed before the patient enters the operating theater.

Performing a preoperative angiogram has several benefits (see the image below). For one, identifying the bleeding vessel during surgery is difficult because of the friability, necrosis, and severe inflammation caused by pancreatitis. Also, because preoperative angiography identifies the bleeding vessel, it may dictate the optimal therapy. (Performing arterial ligation or pancreaticoduodenectomy on bleeding vessels involving the pancreatic head has been demonstrated to carry a high mortality.)

Furthermore, angiography may constitute an opportunity to gain temporary preoperative control over the bleeding vessel by performing transcatheter embolization, thus providing a time window within which the surgeon can operate on a high-risk patient under optimum clinical conditions.

Operative details

A generous midline incision is made from subxiphoid to pubis. Upon entering the peritoneal cavity, all four quadrants should be packed with laparotomy packs. The packs are gradually removed from the least suspicious area for bleeding to the most suspicious area for bleeding.

Once adequate exposure is achieved, direct attention toward the most common source of bleeding—mainly, the peripancreatic vasculature.

Multiple effective measures for gaining rapid control of the actively bleeding pseudoaneurysm have been described. These include manual tamponade, gauze packing, digital compression of the bleeding pseudoaneurysm or pseudocyst, and even supraceliac infradiaphragmatic cross-clamping of the aorta for brisk bleeding.

These measures should be initiated, especially in the actively bleeding hemodynamically unstable patient, while aggressive volume resuscitation is being undertaken by the anesthesia team.

Gaining access to bleeding site

After establishing these initial measures, a more delicate and precise dissection can be performed in order to obtain definitive control of the bleeding vessels. Exposure of the bleeding site can sometimes be challenging, because the surrounding inflammation from pancreatitis obscures the visual field.

Several adjunctive techniques have been listed for gaining operative access to the bleeding pseudoaneurysm; these include gastrotomy, duodenotomy, and major gastrectomy.

Bleeding control techniques

Once the bleeding vessel is identified, the surgeon may employ one of several surgical methods to control the bleeding. The basic surgical principle is to obtain proximal and distal control of the blood vessel before trying to ligate or resect it.

Intracystic ligation without proximal/distal control or resection is not recommended, because the friable tissues of the posterior pseudocyst wall do not hold sutures and the feeding vessel that lies deep within the substance of the pancreas is still patent.

For treatment of the pseudocyst, several surgical options are available, ranging from resection to external or internal drainage methods.

The patient must be carefully monitored after surgery. The occurrence of postresectional hemorrhage is well documented in the literature, with a reported incidence of 5-19% and a mortality of 6-58%. This may be the result of ongoing pancreatitis and continuous damaging of the arteries, iatrogenic trauma to the vessels, or inadequate control of the bleeding vessels.

Whereas some surgeons have advocated surgical ligation of the bleeding vessel in the nonseptic patient and pancreatic resection in those with abscess or established fistula, interventional radiologists have strongly recommended angioembolization for postoperative hemorrhage.