Ischemic Heart Disease

Question 1

What causes Ischemic Heart Disease? What are the risk factors?

Answer 1

Usually due to atherosclerosis of coronary arteries, which decreases blood flow to the myocardium. Same risk factors as atherosclerosis. Incidence increases with age.

Question 2

A 45 year old male who was working out at the gym presents with chest pain that lasted for 15 minutes. He mentions it radiates to his left arm. He was experiencing shortness of breath and diaphoresis. It went away when he sat down to rest. What is causing this presentation? Which structures are damaged? What would you see on EKG? How is it treated? What does it increase the risk of?

Answer 2

Stable angina that arises with exertion or emotional stress. This is due to atherosclerosis of coronary arteries with > 70 % stenosis. Decreased blood flow is not able to meet the metabolic demands of the myocardium during exertion. EKG shows ST-segment depression due to subendocardial ischemia. Relived by rest or nitroglycerin.

Question 3

What happens to myocytes in all angina forms?

Answer 3

Reversible injury without necrosis

Question 4

What is unstable angina? What structures are involved? What is seen on EKG? How is it treated? What does it increase the risk of?

Answer 4

Chest pain that occurs at rest. Due to rupture of an atherosclerotic plaque with thrombosis and incomplete occlusion of a coronary artery. EKG shows ST-segment depression due to subendocardial ischemia. Relived by rest or nitroglycerin. High risk of progression to MI.

Question 5

What is Prinzmetal angina? What structures are involved? What is seen on EKG? How is it treated?

Answer 5

Episodic chest pain unrelated to exertion. Due to coronary vasospasm. EKG shows ST-segment elevation due to transmural ischemia. Relived by nitroglycerin or calcium channel blockers.

Question 6

A 45 year old male who was working out at the gym presents with chest pain that lasted for

Answer 6

Stable angina that arises with exertion or emotional stress. This is due to atherosclerosis of coronary arteries with > 70 % stenosis. Decreased blood flow is not able to meet the metabolic demands of the myocardium during exertion. EKG shows ST-segment depression due to subendocardial ischemia. Relived by rest or nitroglycerin.

Question 7

What is Prinzmetal angina? What structures are involved? What is seen on EKG? How is it treated?

Answer 7

Episodic chest pain unrelated to exertion. Due to coronary vasospasm. EKG shows ST-segment elevation due to transmural ischemia. Relived by nitroglycerin or calcium channel blockers.

Question 8

A 45 year old male who was working out at the gym presents with severe crushing chest pain that lasted for >20 minutes. He mentions it radiated to his left arm. He was experiencing shortness of breath and diaphoresis. He was given nitroglycerin but his symptoms did not resolve. What happened to him? What usually causes this? Which heart compartments are affected by this disorder?

Answer 8

He had a myocardial infarction which is necrosis of cardiac myocytes. Usually due to rupture of an atherosclerotic plaque with thrombosis and complete occlusion of a coronary artery. Infarction usually involves Left ventricle. RV and Atria are spared.

Question 9

Besides atherosclerotic plaque, what are other causes of Myocardial Infarction?

Answer 9

Coronary artery vasosapsm (due to Prinzmetal angina or cocaine use), emboli, and vasculitis (e.g. Kawasaki disease)

Question 10

What is the most commonly involved artery in MI? What does it lead to?

Answer 10

Left Anterior Descending artery. Leads to infarction of the anterior wall and anterior septum of the LV.

Question 11

What is the second most commonly involved artery in MI? What does it lead to?

Answer 11

Right Coronary Artery leads to infarction of the posterior wall, posterior septum, and papillary muscles of the LV.

Question 12

What does occlusion of the left circumflex artery lead to?

Answer 12

Infarction of the lateral wall of the LV

Question 13

What does occlusion of the left circumflex artery lead to?

Answer 13

Infarction of the lateral wall of the LV

Question 14

Which areas are damaged during the initial phase of myocardial infarction? What is seen on EKG?

Answer 14

Subendocardial necrosis involving

Question 15

Which areas are damaged during the contunues/severe phase of myocardial infarction? What is seen on EKG?

Answer 15

Transmural necrosis involving most of the myocardial wall. EKG shows ST-segment elevation.

Question 16

What is the most sensitive and specific marker for MI? When do the levels rise, peak and return to normal?

Answer 16

Troponin I. Levels rise 2 - 4 hours after infarction, peak at 24 hours, and return to normal by 7 - 10 days

Question 17

What is the marker used for detecting reinfarction that occurs days after an initial MI? When do the levels rise, peak and return to normal?

Answer 17

Creatnine Kinase MB (CK-MB) levels rise 4 - 6 hours after infarction, peak at 24 hours, and return to normal by 72 hours

Question 18

What is the marker used for detecting reinfarction that occurs days after an initial MI? When do the levels rise, peak and return to normal?

Answer 18

Creatnine Kinase MB (CK-MB) levels rise 4 - 6 hours after infarction, peak at 24 hours, and return to normal by 72 hours

Question 19

What is the treatment for an MI?

Answer 19

1. Aspirin and heparin to limit thrombosis
2. Supplemental O2 to minimize ischemia
3. Nitrates to vasodilate veins and coronary arteries
4. ACE inhibitor to decrease LV dilation
5. Fibrinolysis or angioplasty to open blocked vessel

Question 20

What are two consequences of opening a blocked vessel?

Answer 20

1. Reperfusion of irreversibly-damaged cells results in calcium influx, leading to hypercontraction of myofibrils (contraction band necrosis)
2. Return of oxygen and inflammatory cells may lead to free radical generation further damaging myocytes (reperfusion injury)

Question 21

When does sudden cardiac death occur? What causes it? What is the most common etiology? What are other less common causes?

Answer 21

Occurs without symptoms or