Question

1. What are the signs and symptoms of a myocardial infarction? What laboratory values and trends reflect a positive myocardial infarction? What is the relationship of a PVC’s to a myocardial infarction?

2. Describe drug eluding stents and the rationale for their use.

3. compare cardioversion and defibrillation .

4. what effect does albumin have on the circulatory system.

5. what are the pharmacokinetics of heparin and morphine ?

Answer 1

Ans)Myocardial Infaction:

-Occurs as a result of sudden interruption in blood supply (primarily CAD) causing necrosis to the myocardium
- cocaine use may cause due to its intense spastic effect to the arteries depriving the heart of oxygen
- Ischemia lasting > 35-45 minutes - produces irreversible cellular damage and necrosis of cardiac muscles
- ST segment elevation MI is usually associated with prolonged and complete coronary thrombosis
- Non ST-segment MI is usually associated with transient thrombosis or incomplete coronary occlusion.

The most common presenting symptom of MI is chest pain, which is often described as severe retrosternal chest pain of a crushing or squeezing nature. Other clues to the differential diagnosis of chest pain are that the pain may radiate to the arms (commonly the left arm), shoulders, neck and/or jaw.

Signs and symptoms of Myocardial Infarction:

-Chest pain (major sign - pain may move to back, shoulder, arm, jaw, abdomen, neck or teeth)
-Anxiety cough
-Fainting
-Lightheadedness or dizziness
-Nausea and vomiting
-Palpitations
-Shortness of breath
-Extreme sweating

Cardiac markers of MI:

Myoglobin
Creatine Kinase ( total and MB fraction )
Cardiac Troponins (cTroponin I and cTroponin T)

Relationship of PVC's to a Myocardial Infarction:

Thrombolytic therapy:

Strict selection criteria: onset of pain <6 hrs, ST segment elevation, ischemic pain, no condition predisposing to hemorrhaging
Given IV or intracoronary - start 2-3 lines
Given IV within 6 hours from onset of pain
complete reocclusion - heparin drip
watch for reperfusion dysrhythmias*

- So PVCs (most common 70-120 min after therapy has started)

2) During a procedure called a coronaryangioplasty, a surgeon will insert a stent into your coronary artery. A stent is a small tube made of metal mesh. It's designed to support your artery walls and prevent plaque from blocking your blood flow. It can help your blood flow more freely to heart.

3) Defibrillation:Electrical current passed through the heart that causes the entire myocardium to depolarize completely at the moment of shock. Produces a transient asystole and then allows the heart's SA node to gain control.

Cardioversion: Synchronized electrical countershock that depolarizes all the cells simultaneously with the patient's QRS. Lower energy used (50-100J) and increases until the rhythm is disrupted. Disrupts an ectopic pacemaker that is causing a dysrhythmia and allows the sinoatrial node to take control of the rhythm.

Difference between Defibrillation & Carioversion:

- The purpose of cardioversion is to disrupt the rhythm rather than completely depolarize the heart, so less energy is needed.

4) Effect of albumin on circulatory system:

Albumin- the smallest and most abundant plasma protein. Contribute to viscosity and osmolarity: influence blood pressure, flow and fluid balance.