Question: Jack, An Apartment Superintendent, Grabbed A Quick Cup Of Coffee And Then Put On His Coat To Shovel Snow Off The Front Sidewalk. He Is 56 Years Old And Has Experienced Two Episodes Of Angina Over The Past 3 Years. This Time When He Was Shoveling The Snow, He Felt Palpitations In His Chest. It Was As Though His Heart Had Stopped And Then Began To Beat …

Jack, an apartment superintendent, grabbed a quick cup of coffeeand then put on his coat to shovel snow off the front sidewalk. Heis 56 years old and has experienced two episodes of angina over thepast 3 years. This time when he was shoveling the snow, he feltpalpitations in his chest. It was as though his heart had stoppedand then began to beat rapidly as if to catch up. Afraid of what hewas feeling, he went inside and called for an ambulance. When theparamedics arrived, they took an ECG and told Jack he was going tobe fine. He was taken to hospital to be seen by an emergencyphysician and was released later that afternoon.

1. The ECG taken by the paramedics showed Jack was experiencingpremature ventricular contractions. In general terms, how do PVCsappear on an ECG? What factors contributed to the onset of PVCs inJack’s situation?
2. Describe the physiologic events in PVC. How is cardiac outputdisrupted with the presence of PVCs?
3. Because of Jack’s history, his PVCs leave him at risk forevents such as ventricular tachycardia or ventricular fibrillation.Compare and contrast these two arrhythmias. Why are theyparticularly dangerous?