Explain why a large pulmonary embolus causes right ventricular strain; relate it to the scenario.

A 45 year old woman is 10 days status post partial small bowel resection for Crohn Disease and has been recuperating at home. She suddenly develops severe shortness of breath, becomes weak, and her blood pressure drops to 80/40 mmHg (previous readings 130/80 mmHg). The pulse oximetry is 89% on room air. While waiting for the Emergency Medical Service ( EMS) to arrive, the APRN places EKG leads and the EKG demonstrates right ventricular strain. Explain why a large pulmonary embolus causes right ventricular strain; relate it to the scenario.