Coronary artery disease / IHD

Question 1

What is ischaemia?

Answer 1

Reduced blood supply to tissue.

Reduce O2 and glucose.

Question 2

What is infarction?

Answer 2

Tissue death due to ischaemia.

Question 3

What is coronary heart disease?

Answer 3

Reduced blood flow to heart - coronary arteries.

coronary arteries are branches of ascending aorta supplying heart muscle.

Question 4

What is the most common cause of ischaemia?

Answer 4

atherosclerosis

Question 5

What can cause coronary artery disease?

Answer 5

• atheroma (atherosclerosis)
• thrombosis (solidification of blood constituents often on top of atheroma).
• vasospasm (prinzmetals angina) - contraction of blood vessel wall, smooth muscle.
• embolus (rare) (vascular obstruction at a site distant from origin of the embolus, could originate from a thrombus.
• Coronary arteritis (i.e. SLE) (systemic lupus erythematosus. vascular autoimmune disease.

Question 6

Symptoms of IHD

Answer 6

CHEST PAIN
central, crushing/heavy in nature. constant.
Discomfort in chest, neck, shoulders and/or jaws.
May be associated pallor, sweating, nausea, and vomiting. may have shortness of breath, palpitation and/or syncope (alone or with chest pain).

Question 7

What are symptoms of stable angina?

Answer 7

induced by exercise. other potential triggers include cold weather, heavy meals and stress.
pain relieved by rest and/or GTN in <5mins.

Question 8

What is ACS? ACS (acute coronary syndrome) levels

Answer 8

unstable angina
myocardial infarction
–> NSTEMI (Non ST elevation MI)
–> STEMI (ST elevation MI)

Fibrous cap of atheromatous plaque ruptures, platelet activation & thrombosis, some platelet activated vasospasm.

Question 9

What are the symptoms of ACS?

Answer 9

onset may be at rest/spontaneous.
not relived by rest or GTN, often lasts >30 mins.
sympathetic symptoms more prominent.
impending sense of doom. sudden cardiac arrest/die.

Question 10

What is atherosclerosis?

Answer 10

pathological, focal, asymmetric narrowing of the arterial lumen due to atheromatous plaque build up.

Question 11

Describe the process of atherosclerosis 4)

Answer 11

1. LDL accumulation
   - oxidation
2. Macrophages
   - phagocytosis of ox-LDL via scavenger receptors
   - foam cells
3. Accumulation, apoptosis, and necrosis.
   - necrosis, cell debris and formation of cholesterol core.
4. Fibrous cap
   - inflammation
   - smooth muscle and collagen
   - subsequent macrophage led thinning

Question 12

What are the stages of atherosclerosis (3)

Answer 12

Fatty streak - lipid laden macrophages, minimal free lipid - minimal inflammation

Fibrous plaque - cholesterol rich lipid core - smooth muscle proliferation

Complicated fibrous plaque - surface ulceration, thromboembolism, plaque rupture, plaque growth.

Question 13

What are the risk factors of arterial diseases? (5)

Answer 13

Smoking
Hypertension
Cholesterol
Family history
Diabetes

others: age, male, raised CRP, high saturated fats in diet, obesity.

Question 14

What are the diagnostic test to identify type of coronary artery disease? (3)

Answer 14

1. Clinical history (stable angina or ACS)
2. Troponin (unstable angina or MI)
   - -protein present in cardiac myocytes, if infarction, released and detected in bloodstream.
3. ECG (MI: NSTEMI or STEMI)
   - - over 2mm elevation in 2 or more adjacent chest leads.

others: 
Angiography 
Myocardial perfusion study
Stress Echocardiogram
Exercise ECG (treadmill test)
CT calcium scoring or CT angio

Question 15

How do you manage ACS?

Answer 15

O2, GTN, pain control (morphine), anti-emetics (metoclopramide), anti-platelet meds (aspirin, clopidogrel), Factor Xa inhibitors (fondaparinux).

Question 16

How do you prevent CV disease?

Answer 16

• Risk factor modification, aspirin, statin, ACEi, anti-anginal (beta blocker or Ca-Channel blocker.
• Others are second line (nicorandil, long acting nitrates).

invasive (if continued symptoms)

• PCI = percutaneous coronary intervention (coronary angioplasty) removes clot.
• thrombolysis (clot busting drug).
• CABG - coronary artery bypass graft, remove clogged vessel and replace with clean vessel.

Question 17

What dental concerns are there with ACS pts? (5)

Answer 17

1. Stress and pain will cause incr myocardial demand
   - -> reduce appt times, delay treatmetn 3-6 monts post MI
2. LA with adrenaline could cause probs
   - -> generally only if given IV.
   - -> aspirate syringe.
   - -> avoid high doses
3. GA/sedation avoided if possible
4. Medical side-effects
   - -> calcium channel blockers cause gingival hyperplasia.
   - -> nicorandil causes ulceration
5. Drug interactions
   - -> Statins: macrolide antibiotics (erythromycin etc) and azole antifungals (fluconazole etc) may incr risk of statin-related myopathy.
   - -> Anti-platelets (aspirin/clopidogrel): increases bleeding risk post-extraction. Surgicel and suturing may be required.

Question 18

What is angina?

Answer 18

Angina is crushing central chest pain. It is due ischaemia in the coronary arteries which causes reduced blood supply to the heart muscle.

Question 19

What is acute coronary syndromes? (ACS)

Answer 19

Acute coronary syndrome is a term used to describe a range of conditions associated with sudden, reduced blood flow to the heart.
These conditions include unstable angina, NSTEMI and STEMI.

Its onset may be at rest/spontaneous.

Question 20

What are the characteristic of stable angina?

Answer 20

Chest pain with extertional and/or emotional stress

Question 21

What may be seen on an ECG in a patient with unstable angina?

Answer 21

ST depression and T wave inversion

Question 22

What is the most important cause of cardiac death?

Answer 22

Ventricular arrhythmia
(ventricular fibrillation, ventricular tachycardia)

pneumonia or MI or sepsis pushes patient into VF