massive saddle pulmonary embolismbilateral saddle pulmonary embolismacute saddle pulmonary embolismsaddle block pulmonary embolismpulmonary embolism saddle clotsaddle pulmonarysaddle embolism treatmentsaddle pulmonary thromboembolismsaddlebag pulmonary embolismlung blood clot survival ratesaddle embolus of pulmonary arterysaddle block embolism