Pulmonary thrombectomy

Overview
In thoracic surgery, a pulmonary thrombectomy, is an emergency procedure that removes clotted blood (thrombus) from the pulmonary arteries. Embolectomy can be done via a catheter or surgically.

Indications

 * Pulmonary embolism patient (formed from venous embolisms). Embolectomy is used for patients with persisting shock despite supportive care and who have an absolute contraindication for thrombolytic therapy.
 * Arterial embolisms in acute limb ischemia.
 * Other ischemias due to embolism (mesenteric ischemia and stroke).

Transcatheter procedures can be performed as an alternative to thrombolysis when
 * Thrombolysis is contraindicated.
 * When emergency surgical thrombectomy is unavailable or contraindicated.
 * When thrombolysis has failed to improve the patient's hemodynamics in the acute setting.

Therapeutic Goal
The goals of catheter-based therapy include
 * Rapidly reduce pulmonary artery pressure, RV strain, and pulmonary vascular resistance (PVR).
 * Improve hemodynamics.
 * Facilitate right ventricular recovery.

Types

 * Catheter embolectomy: It is a treatment option for patients having contraindications to fibrinilytics or who are at institutions where surgical embelectomy is not available. It is broadly divided into two types:
 * . Rheolytic embolectomy
 * . Rotational embolectomy
 * Surgical embolectomy

Description
Rheolytic embolectomy: Pressurized saline is passed through a catheter's distal tip, which breaks-down the emboli. The saline and clot fragments are then sucked back into an exhaust lumen of the catheter and disposed off.

Insertion of a large catheter increases the risk of bleeding which pose as the major disadvantage.

Rotational embolectomy: As the name suggest, a rotational device is used to fragment the thrombus. In this, cardiac catheters are used, which does not require venotomy at the puncture site. The fragments are continuously aspirated. Mechanical thrombectomy should be limited to the main and lobar pulmonary arterial branches, because the risk of perforation increases, when vessels smaller than 6 mm in diameter are treated. Other complications are:
 * Complications:
 * Puncture or dissection of cardiopulmonary structures.
 * Pulmonary hemorrhage.
 * Pericardial tamponade.
 * Distal Thrombus embolization.

Surgical embolectomy: This procedure is typically limited to large medical centers (as it requires experienced surgeon and cardiopulmonary bypass).
 * Indications
 * Hypotensive patients in which thrombolysis is contraindicated.
 * Embolus trapped within patent foramen ovale, right atrium or the right ventricle, as evident on Echocardiography.
 * Benefits
 * Among patients failing initial thrombolysis, surgical embolectomy was found to have fewer death rates and fewer major bleedings.
 * Special Considerations
 * A study had shown the presence of extrapulmonary thrombus in 13 out of 50 patients undergoing surgical embolectomy, thus emphasizing the need of transesophageal echocardiography (TEE). TEE should be performed before or during the procedure to look for extrapulmonary thrombus. Extrapulmonary thrombus are thrombus present in right atrium, right ventricle, or inferior vena cava.

Guidelines
To read about about AHA/ACC Guidelines for surgical and catheter embolectomy, click here.

Relation to PTE
Pulmonary thrombectomies and pulmonary thromboendarterectomies (PTEs) are both operations that remove thrombus. Aside from this similarity they differ in many ways.
 * PTEs are done non-emergently whilst pulmonary thrombectomies are typically done as an emergency procedure.
 * PTEs typically are done using hypothermia and full cardiac arrest.
 * PTEs are done for chronic pulmonary embolism, thrombectomies for severe acute pulmonary embolism.
 * PTEs are generally considered a very effective treatment, surgical thrombectomies are an area of some controversy and their effectiveness a matter of some debate in the medical community.