A fit, physically active 32-year-old female with no underlying risk factors underwent a left knee anterior cruciate ligament (ACL) reconstruction and partial lateral meniscectomy. She was not taking oral contraceptives. She presented 19 days postoperatively with acute dyspnea, chest pain, tachycardia, and complaints of feeling light-headed of 5 days duration. In the emergency department, she had sinus tachycardia on electrocardiography, a heart rate of 126 bpm, blood pressure of 107/68 mmHg, respiratory rate of 18/min, and an oxygen saturation of 95% on room air. Her examination was noted to be otherwise unremarkable. There was no evidence of surgical site infection and no limb swelling noted. A complete blood count and electrolyte and metabolic panel were normal. Her troponin was 80 ng/L (normal 0-14 ng/L). A chest radiograph and D-dimer were not performed. Her pretest probability of pulmonary embolism was moderate based on Wells' criteria.
Computed tomography pulmonary angiogram (CTPA) reported the patient as having PTE. Findings included saddle PE, extensive clot extending into lobar and segmental branches of all lobes (Figure 1) as well as evidence of right heart strain with marked right atrial (RA) and RV dilation as well as flattening and deviation of the interventricular septum. The RV/LV ratio was 1.3. Unfractionated low-molecular-weight heparin was immediately initiated. Her simplified PE Severity Index (sPESI) was 1 (high risk, 8.9% mortality).
The patient was admitted to the Internal Medicine service. On day 1, her clinical status was unchanged; laboratory indices were similar with a troponin level of 35 ng/L and NTpro-BNP of 3859 ng/L (normal 0-300). ICU was consulted on day 1 of admission, and a transthoracic echocardiogram (TTE) was immediately requested. This demonstrated a 3.3 cm maximum diameter multilobulated, mobile right atrial thrombus, which extended from the RV inlet through the pulmonic valve to the pulmonary artery (i.e., an RHTT). Intraventricular septal flattening and severe RV dilation with moderate systolic dysfunction and tricuspid regurgitation were also observed. McConnell's sign was present with apical hypercontractility and basal and mid-ventricular segmental hypokinesis. The right ventricular systolic pressure (RVSP) was 48.1 mmHg (Figure 2).
She was transferred to the intensive care unit (ICU) with a diagnosis of clinical submassive pulmonary embolism with clot in transit. Arterial blood gas was pH 7.52, pCO2 29 mmHg, PaO2 74 mmHg, O2 saturation 96%, and lactate 0.8 mmol/L. The case, as well as treatment options, was reviewed with a member of the pulmonary embolism response team (PERT). A decision was made to proceed with low-dose thrombolysis, despite the recent surgery, employing the regimen described in the MOPETT trial. The potential benefits and risks were discussed with the patient who consented. She received a 10 mg recombinant tPA bolus followed by an additional 40 mg over two hours intravenously (IV). IV heparin was continuously infused at 10 U/kg/hr during the thrombolysis as well and for three hours afterwards at which time the heparin nomogram infusion of 18 U/kg/hr with serial adjustments based on PTT was re-introduced. Serial echocardiograms at 2 hours after thrombolysis and the next day (Figure 3) demonstrated improvement in her RV function. The RVSP was 27 mmHg at 2 hours and 26 mmHg the following day. The in-transit clot was no longer visible on the posttreatment echocardiograms. She was eventually discharged home on day 5 on tinzaparin for two weeks and then transitioned to rivaroxaban. She was continued on anticoagulation for 6 months.
Seven months after discharge, she was doing very well. Her breathing had returned back to baseline, and she was rehabilitating well from her reconstruction. She had no bleeding complications from the rivaroxaban therapy. Her DASH score was 1 (3.9% annual risk of DVT recurrence), and her HERDOO2 score was 0 (3% risk of major recurrent venous thromboembolism per 100 patient years). The anticoagulation was discontinued. She had returned to the gym, though had not yet returned to more vigorous-intensity physical activities, such as basketball. A repeat echocardiogram at this time demonstrated normal left and right ventricular systolic function with no hemodynamically significant valvular disease. Serial D-dimers, every three months, for the following year were scheduled. Testing for inherited thrombophilia was negative.