Treatment of hemodynamically unstable (high-risk) PE

BNP: brain natriuretic peptide; CDT: catheter-directed therapy; CPR: cardiopulmonary resuscitation; CTPA: computed tomographic pulmonary angiography; IVC: inferior vena cava; PE: pulmonary embolism; PERT: PE response team; RV: right ventricle; tPA: tissue plasminogen activator; UFH: unfractionated heparin.

* Hypotension, obstructive shock, and cardiac arrest from PE are due to significant RV dysfunction, which is usually evident on bedside echocardiography or biochemically when elevated RV markers are seen (eg, BNP, N-terminal BNP, troponin). RV dilation may also be appreciated and able to safely tolerate undergoing CTPA after resuscitation. Evaluation with a PERT or expert consultant is advisable to facilitate the decision since systemic thrombolysis is associated with a high risk of major bleeding (up to 20% compared with 3% on anticoagulant therapy). Most worrisome is the risk of intracranial hemorrhage (1.5 versus 0.2%).

¶ Clinically significant hypotension is defined as a systolic blood pressure <90 mmHg or hypotension that requires vasopressors or inotropic support despite adequate filling status in combination with end-organ hypoperfusion; persistent hypotension or a drop in systolic blood pressure of ≥40 mmHg from baseline for a period >15 minutes; hypotension not explained by other causes, such as hypovolemia, sepsis, arrhythmia, or left ventricular dysfunction from acute myocardial ischemia or infarction.

Δ Emboli can be removed surgically or using catheter-directed techniques. Catheter-directed techniques are preferred since the surgical risk associated with open surgical embolectomy is high. Catheter-directed techniques involve mechanical disruption or removal. Small doses of thrombolytic agent may be administered via the catheter in conjunction with or separate to mechanical removal. The choice between these options depends upon available expertise, the presence or absence of a known diagnosis of PE, underlying comorbidities, and the anticipated response to such therapies.

◊ We favor systemic thrombolysis over catheter-directed thrombolysis based on limited data that show early, rapid, and life-saving hemodynamic improvement with systemically administered tPA. If there is a delay in therapy, patients should be anticoagulated, preferably with UFH. Refer to UpToDate text on thrombolytic administration and efficacy of tPA.

§ Tenecteplase is an alternative. Dosing is the following (typical weight based regimen [bolus infusion]):

• ≤60 kg – 30 mg intravenous
• 61 to 69 kg – 35 mg intravenous
• 70 to 79 kg – 40 mg intravenous
• 80 to 89 kg – 45 mg intravenous
• ≥90 kg – 50 mg intravenous

¥ UFH is generally the initial anticoagulant of choice, although low molecular weight heparin is not a contraindication to thrombolysis. We prefer UFH after thrombolysis in case bleeding occurs, in which case the infusion can be quickly terminated.