Description

Episode 2: Oren Friedman interviews Ken Rosenfield on catheter directed lytics.

Oren Friedman MD
Associate Director, Cardiac Surgery ICU 
Pulmonary Critical Care 
Cedars-Sinai Medical Center

Ken Rosenfield, MD, MHCDS
Section Head, Vascular Medicine and Intervention 
Division of Cardiology 
Mass General Hospital

What is catheter directed thrombolysis (CDT)?

• Placing a catheter via femoral or IJs into pulmonary arteries and infusing low dose thrombolytic over extended period.
• Percutaneous mechanical thrombectomy differs as it involves extracting thrombus from pulmonary artery. (mostly from proximal pulmonary arteries, and no thrombolytic regimen used in this method)

MOA of CDT compared to peripheral systemic thrombolysis

• More clot bound thrombolytic directly into the clot compared to around the clot with systemic tPA.
• Increased local thrombolytic concentration.
• Reduced tPA and longer duration of infusion—reason for increased safety profile for ICH and major bleeding compared to full dose systemic tPA. (dose is 100 mg, ICH rates 3-5%)
• CDT also allows improve tPA infusion to into distal pulmonary circulation bed. (Vs percutaneous mechanical embolectomy)

Technical aspects of CDT:

• Pulmonary angiogram is not always needed at time of CDT or post CDT.
• Decision to place unilateral or bilateral catheters (right, left or both branches of pulmonary artery) depends on location of clot based on CTA.
• Patient are usually monitored in ICU while drugs are infusing, close monitoring and experienced clinical nursing staff should be involved.
• Heparin during CDT: fix dose 300-500 unit/per catheter sheaths. Hard to achieve targeted aPTT (40-60) given very short duration of infusion. Fibrinogen to guide tPA duration- limited to no data
• Catheter directed thrombolysis with (EKOS) ultrasound or without ultrasound: We just don't know. The available data stems from prospective clinical trials with ultrasound catheters.
• Sedation: be careful with sedation. Use minimum. Avoid intubation for procedure itself.

What is successful CDT?

• Goal is to improve hemodynamics, not to remove all thrombus. Drop in pulmonary artery pressures (if monitoring available) or improved RV/LV ratio in pre-vs Post intervention imaging. [Echo or CTA]

Data on CDT

• Impact on RV/LV ratio, as primary goal of improvement in many trials (see Table below)

1. 1. ULTIMA trial: Heparin Vs CDT, with EKOS catheters. Rapid normalization of RV/LV ratio compared to heparin alone in immediate period. No difference at 90 days. Small numbers to show impact on mortality.
   2. SEATTLE II trial -- also included massive PE patients.
   3. PERFECT registry: prospective registry showing safety and efficacy of CDT.
   4. OPTALYSE trial: compared different CDT dosing regimens.

• Impact on long term disability like CTED or CTEPH remains to be seen.

Dosing regimens for of CDT: (See Table below)

• Higher risk bleeding patients: use as low as dose possible.
• OPTALYSE trial: Lower dose (as low as 4-8 mg) and shorter duration are effective for hemodynamic improvement. Higher doses were associated with better Miller clot burden improvement with increased risk of bleeding. (2 ICH incidents)

Rali P, Criner J. Am J Respir Crit Care Med. 2018 Sep 1;198(5):588-598