How to manage a patient with a saddle embolus and bilateral pulmonary embolism (PE)?

Management of Saddle Embolus and Bilateral Pulmonary Embolism

Patients with saddle embolus and bilateral PE should receive immediate thrombolytic therapy if hemodynamically unstable, or anticoagulation with consideration for catheter-directed or surgical intervention if stable but with right ventricular dysfunction. 1

Initial Risk Stratification

Risk stratification is crucial for determining appropriate management:

1. High-risk (massive) PE:

   • Characterized by hemodynamic instability (systolic BP <90 mmHg or drop of ≥40 mmHg for >15 minutes)
   • Cardiac arrest
   • Obstructive shock

2. Intermediate-risk (submassive) PE:

   • Hemodynamically stable but with right ventricular dysfunction
   • Elevated cardiac biomarkers (troponin, BNP)

3. Low-risk PE:

   • Hemodynamically stable
   • No evidence of RV dysfunction

Management Algorithm Based on Risk Stratification

High-Risk (Massive) PE with Hemodynamic Instability

1. Thrombolytic Therapy:

   • First-line treatment for patients with high-risk PE 1
   • Alteplase (rtPA) 100 mg over 2 hours or 0.6 mg/kg over 15 minutes (maximum 50 mg)
   • Consider in cardiac arrest suspected to be PE-related

2. If Thrombolysis Contraindicated or Failed:

   • Catheter-directed embolectomy and fragmentation 2
   • Surgical embolectomy 2

3. Anticoagulation:

   • Unfractionated heparin (UFH): 80 U/kg bolus followed by 18 U/kg/hour infusion 2
   • Target aPTT 1.5-2.5 times control

Intermediate-Risk (Submassive) PE with RV Dysfunction but Hemodynamically Stable

1. Initial Anticoagulation:

   • Low molecular weight heparin (LMWH) preferred over UFH 2, 1
   • Enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily
   • Fondaparinux: 5 mg (<50 kg), 7.5 mg (50-100 kg), or 10 mg (>100 kg) once daily 3
   • UFH if rapid reversal may be needed or severe renal impairment

2. Consider Catheter-Based Intervention:

   • For patients with extensive clot burden (saddle embolus)
   • If clinical deterioration occurs despite anticoagulation
   • Catheter-directed techniques include aspiration thrombectomy, fragmentation, or rheolytic thrombectomy 2

3. Monitor Closely:

   • Continuous assessment of hemodynamic parameters
   • Serial evaluation of RV function
   • Watch for signs of clinical deterioration

Low-Risk PE (Hemodynamically Stable, No RV Dysfunction)

1. Anticoagulation:
   • LMWH or fondaparinux 1
   • Direct oral anticoagulants (DOACs) can be started immediately without parenteral anticoagulation lead-in

Special Considerations for Saddle Embolus

A saddle embolus refers to a thrombus located at the bifurcation of the main pulmonary artery. While the presence of a saddle embolus alone does not necessarily dictate more aggressive treatment 4, it often correlates with higher clot burden and potential for hemodynamic compromise.

Key considerations:

• Echocardiography should be performed promptly to assess RV function
• Even if initially asymptomatic, patients with saddle emboli require close monitoring for deterioration
• The presence of a patent foramen ovale (PFO) increases risk of paradoxical embolism and may warrant more aggressive therapy 2

Procedural Techniques for Catheter-Based Interventions

If catheter-based intervention is pursued:

1. Approach:

   • 6F femoral venous sheath
   • 6F angled pigtail catheter advanced into each main pulmonary artery
   • Anticoagulation with UFH (70 IU/kg bolus) or bivalirudin (0.75 mg/kg bolus, then 1.75 mg/kg/h) 2

2. Techniques:

   • Rheolytic thrombectomy (AngioJet, Hydrolyser, Oasis)
   • Rotational thrombectomy (Rotarex, Aspirex)
   • Fragmentation with pigtail catheter

3. Post-Procedure:

   • Continue anticoagulation
   • Monitor for bleeding complications
   • Assess improvement in hemodynamics and RV function

Duration of Anticoagulation

• Minimum 3 months for provoked PE 1
• Extended anticoagulation (>3 months) for unprovoked PE or persistent risk factors
• Indefinite anticoagulation for recurrent PE

Follow-up and Monitoring

• Continuous assessment of hemodynamic parameters
• Serial evaluation of RV function if initially abnormal
• Reevaluation 3-6 months after acute episode to detect post-thrombotic syndrome and chronic thromboembolic pulmonary hypertension

Common Pitfalls and Caveats

1. Delay in treatment initiation: Recognize that saddle embolus represents a potentially life-threatening condition requiring immediate intervention.

2. Overreliance on diagnostic labels: The term "saddle embolus" describes location but doesn't automatically dictate treatment strategy - clinical status and RV function are more important.

3. Failure to recognize deterioration: Patients may initially appear stable but can rapidly deteriorate - close monitoring is essential.

4. Inappropriate thrombolysis: Thrombolysis carries significant bleeding risk and should be reserved for appropriate patients with high-risk PE.

5. Inadequate anticoagulation: Ensure therapeutic anticoagulation is achieved and maintained.

6. Overlooking PFO: Screen for PFO in patients with PE as it increases risk of paradoxical embolism and may warrant more aggressive therapy 2.