A 62-year-old woman with a history of recent hip fracture (immobilized for 2 weeks) presents with acute onset dyspnea and syncope. On examination: BP 88/54 mmHg, HR 128/min, RR 32/min, JVD present, right ventricular heave palpable. Troponin is elevated at 0.18 ng/mL (normal <0.04). Bedside echocardiography shows RV dilatation with RV/LV ratio 1.8 and elevated TR velocity. What is the most appropriate immediate management?