Question

Case Study #2: Chest Pain at a Super Bowl Party

56-year-old Roger is watching the Super Bowl with his friends. He’s eating a lot of fried food, even though he knows his doctor told him not to eat those foods because of his heart health. He doesn’t think that today should matter too much though, since it’s the super bowl and all. He’s having a good time with his friends and family until he starts having chest pain. He thinks nothing of it at first, as it is a dull pain. Then he becomes very sweaty and nauseous. His wife says to him that he looks very pale. Roger also becomes very faint. Roger’s wife calls 911.

When EMS and the Fire Department arrives, the paramedics and EMTs approach Roger and start asking him questions. Roger tells them he is having chest pain. The paramedics attach Roger to a cardiac monitor and performs an ECG recording while measuring his vital signs. The paramedics also start asking questions about his history and give him chewable aspirin for his chest pain. He tells them that he has had a heart attack 6 months ago, and is on medications to lower his cholesterol. One of the paramedics looks at the ECG and then looks at his partner.

“The patient is having a STEMI.” States the paramedic to his partner.

Roger gets a confused look on his face. “What’s a STEMI?” he asks.

The paramedic looks at roger and says “Sir, the ECG shows you are having a ST-Elevation Myocardial Infarction. It is also known as a ‘heart attack’. We need to get you to the hospital as soon as possible.”

Roger nods his head. The paramedics get Roger moved over to the stretcher and loads him into the ambulance. A firefighter-paramedic also gets in the back to assist the lead paramedic. While enroute to the hospital going lights and sirens, the paramedics start an IV and give him nitroglycerin. They give him morphine to treat the pain, which significantly reduces Roger’s pain. Roger is now sitting comfortably in the ambulance.

Suddenly, Roger goes unconscious. One paramedic checks the patient’s pulse while the other paramedic checks the cardiac monitor. He sees this:

The paramedic checking the pulse states that there is no pulse. One of the paramedics puts a bag valve mask on the patient while the other starts CPR. The first paramedic then gives Roger epinephrine via the IV. After 2 minutes, Roger’s rhythm and pulse are checked. The paramedic checking the monitor sees this:

The paramedic checking the pulse states that there is no pulse. They immediately defibrillate Roger at 360 Joules. One of the paramedics states the patient has normal sinus rhythm and the other paramedic checks a pulse and states that Roger has a pulse. The paramedics then check his vital signs again. The paramedics also call into the hospital to say they are 5 minutes away and that Roger is having a STEMI.

Roger then wakes up and asks what happened.

“You went into cardiac arrest, sir. Your pulse stopped and you stopped breathing. We’re almost to the hospital.”

Roger looks surprised, but just nods his head. At this moment, the ambulance is backing into the ER bay. The paramedics take him inside, where they take him straight into the cardiac cath lab for a coronary angioplasty with stent placement.

Roger has a successful surgery and stays in the hospital for one week before being discharged home in good health.

Questions:

7. What is the name of the rhythm that is seen in the second ECG output? What is happening in the heart when this rhythm is seen? Make sure to identify which chambers of the heart are affected. What is the purpose of defibrillating in response to that rhythm? Make sure to address in your answer how defibrillation would affect cardiac action potentials. (2 pts)

Answer 1

The second ECG shows the cardiac rhythm of Asystole. It is the absence of electrical activity due to sudden cardiac arrest. In cardiac arrest, the heart develops an arrhythmia that stops the beating of heart suddenly. The lower chamber of the heart (ventricles) is affected by ventricular fibrillation. It should be treated immediately otherwise lead to death. The patient should immediately start with CPR and defibrillator. Defribillator produces an electric shock which restores the heart rhythm to normal. When the voltages pass, a strong force of contraction of cardiac muscles initiates the depolarization. This was followed by normal repolarization and the generating signals restore the normal heart function.