Pulmonary artery (PA) false aneurysm (PAFA) formation, induced by a Swan-Ganz catheter is a well known complication. It is estimated to occur in 0.06 to 0.2% of cases with a PA-catheter and is associated with a mortality rate of 45 to 65%.[1, 2]

Established risk factors include female patients, an age greater than 60 years, the presence of pulmonary hypertension [3], anticoagulation, stiff catheters (hypothermic cardiopulmonary bypass) [4], repeated manipulations during cardiopulmonary bypass (CPB) with migration of the PA-catheters distally as well as leaving the catheter in its original position during CPB. [5, 1, 6]

There are various mechanisms possible:

direct rupture of the vessel by the inflated balloon or by the catheter tip itself, e.g. by eccentric inflation of the balloon. It is noteworthy to remember, that the pressure in a correct inflated balloon is about 300 mmHg. This pressure is exceeded two- to three-times while inflating such a balloon. [1]

The pathogenetic mechanism in the development of the formation of a PAFA includes the laceration of the vessel wall with direct bleeding into the pulmonary parenchyma. When this bleeding extends into the airways, hemoptysis will result. A rupture through the visceral pleura on the other hand can lead to a hemothorax. Very small lacerations sometimes reendothelialize. PAFA's do not have any intact vessel layer. The aneurysmal sac is formed only by compressed lung parenchyma. [7]

This leaves these aneurysms prone to rupture since they are inherently unstable. [8]

The signs are related to the pathogenesis: new pulmonary infiltrates in the region of the tip of the PA-catheter, hemoptysis, hemothorax or pericardial tamponade (rare) [5].

Due to its high mortality the diagnosis of an PAFA after an initial bleeding is essential. Radiologic findings are well-defined, persistent, pulmonary nodules or masses adjacent to the catheter tip.

The method of choice in diagnosing PAFA's has been said to be contrast enhanced CT-scans, especially in patients with pulmonary hypertension. Pulmonary angiography is the second diagnostic tool. [1, 8]

The goals of any therapeutic approach are as follows:

• Decrease bleeding
• Correct hypovolemia
• Preserve the function of the unaffected lung
• Preserve gas-exhange
• Localize the source of the bleeding

To achieve this goal, the following recommendations have been made:

Position the patient with the affected lung dependent to prevent soiling of the contralateral lung. After separation of both lungs (either with a bronchial blocker or with a double-lumen tube) the affected lung should be positioned uppermost to reduce the pulmonary artery pressure.

Hemostasis should be controlled by reversal of the heparin (if used e.g. for CPB), replacement of platelets and administration of coagulation factors (fresh-frozen-plasma).

As soon as the patient is stable enough, diagnosis should be made and embolisation of the branch of the pulmonary artery should be attempted, using stainless steel wire coils. [9, 10, 11]

Surgical therapeutic options include direct repair of the vessel (seldom) or resection of the affected lung segment.

In cases with severe bleeding an aggressive surgical approach is mandatory: chest tubes should be placed in large hemothorax (autotransfusion should be considered) and temporary ligation of one PA could be necessary.

Pulmonary bleeding after restoration of spontaneous circulation after CPB should be an early warning sign. Resuming CPB and exploration of the surgical field may be necessary. [5, 11, 2]

To prevent every case of PA-catheter related PAFA probabely is not possible. Special attention should be paid to the described risk-factors. PA-catheters should be without any technical failure and the balloon at the tip should inflate symetrically. Withdrawal of the PA-catheter a few centimeters before CPB is mandatory.