1. CORONARY ARTERY DISEASE (CAD)
LECTURE 1
DR ZAHOOR ALI SHAIKH

2. CORONARY ARTERY DISEASE (CAD)
What is Coronary Artery Disease?
CAD is heart disease due to impaired coronary blood flow.

3. CORONARY ARTERY DISEASE (CAD)
CAD can cause
- Myocardial ischemia or Angina called
Ischemic heart disease (IHD)
- Myocardial infarction or Heart attack
- Conduction effect
- Heart failure
- Sudden death

4. First we will discuss normal coronary circulation and factors affecting it.
Then we will discuss Ischemic heart disease.

5. CORONARY CIRCULATION
Coronary vessels travel across the surface of heart under epicardium.
Heart is supplied by TWO CORONARY arteries:
1- Left coronary artery---(LCA)
2- Right coronary artery---(RCA)
These coronary arteries arise at the root of the aorta.

6. Coronary artery & their branches
Left coronary artery is about 3.5cm and then divides into
LCA Lt Anterior Descending (LAD)
-Circumflex Artery
Right Coronary Artery
RCA Marginal Artery
-Posterior descending branch

7. LEFT CORONARY ARTERY
LAD--- Supplies anterior and apical parts of heart ,and Anterior 2/3rd of interventricular septum.
Circumflex branch-- supplies the lateral and posterior surface of heart.

8. Right coronary artery(RCA) supplies:
Right ventricle
Part of interventricular septum (posterior 1/3rd)
Inferior part of left ventricle
SA Node
AV Node

9. Diagram of coronary circulation

10. Blood flow to Heart during Systole & Diastole
During systole when heart muscle contracts it compresses the coronary arteries therefore blood flow is less to the left ventricle during systole and more during diastole.
To the subendocardial portion of Left ventricle it occurs only during diastole

11. Coronary blood flow to the right side is not much affected during systole.
Reason---Pressure difference between aorta and right ventricle is greater during systole .

12. CORONARY BLOOD FLOW DURING SYSTOLE AND DIASTOLE

13. Effect of Tachycardia on coronary blood flow:
During increased heart rate, period of diastole is shorter therefore coronary blood flow is reduced to heart during tachycardia.

14. As we know blood flow to subendocardial surface of left ventricle during systole is not there, therefore, this region is prone to ischemic damage and most common site of Myocardial infarction.

15. Other causes of decreased blood flow to left ventricle
1-Aortic stenosis
Reason---As left ventricle pressure is very high during systole, therefore, it compresses the coronary arteries more.
2-When aortic diastolic pressure is low, coronary blood flow is decreased

16. CORONARY BLOOD FLOW
Coronary blood flow in Humans at rest is about ml/minute, about 5% of cardiac output.
At rest, the heart extracts 60-70% of oxygen from each unit of blood delivered to heart [other tissue extract only 25% of O2.

17. CORONARY BLOOD FLOW Why heart is extracting 60-70% of O2?
Because heart muscle has more mitochondria, up to 40% of cell is occupied by mitochondria, which generate energy for contraction by aerobic metabolism, therefore, heart needs O2.
When more oxygen is needed e.g. exercise, O2 can be increased to heart only by increasing blood flow.

18. Factors Affecting Blood Flow to CORONARY ARTERIES
-Pressure in aorta
-Chemical factors
-Neural factors
NOTE—Coronary blood flow shows considerable Autoregulation.

19. Chemical factors affecting Coronary blood flow
Chemical factors causing Coronary vasodilatation (Increased coronary blood flow)
-Lack of oxygen
-Increased local concentration of Co2
-Increased local concentration of H+ ion
-Increased local concentration of k + ion
-Increased local concentration of Lactate, Prostaglandin, Adenosine, Adenine nucleotides.
NOTE – Adenosine, which is formed from ATP during cardiac metabolic activity, causes coronary vasodilatation.

20. Neural factors affecting Coronary Blood Flow
-Effect of Sympathetic stimulation
-Effect of Parasympathetic stimulation
Sympathetic stimulation
Coronary arteries have
Alpha Adrenergic receptors which mediate vasoconstriction
Beta Adrenergic receptors which mediate vasodilatation

21. Sympathetic stimulation------Cont
Effect of sympathetic stimulation in intact body---Epinephrine and Norepinephrine causes Coronary VASODILATATION.
HOW ?
But the Direct effect of sympathetic on Coronary arteries is VASOCOSTRICTION.
WHY ?

22. Effect of Parasympathetic stimulation
-Vagus nerve stimulation (Parasympathetic) causes coronary vasodilatation

23. NUTRIENT SUPPLY TO HEART
Heart uses primarily free fatty acids and to lesser extent glucose and lactate for metabolism.

24. CORONARY ARTERY HEART DISEASE
ISCHEMIC HEART DISEASE (IHD) (ANGINA PECTORIS)
MYOCARDIAL INFARCTION
ANGINA PECTORIS:
THERE IS REDUCED CORONARY ARTERY BLOOD FLOW DUE TO ATHEROSCLEROSIS (CHOLESTROL DEPOSITION SUBENDOTHELIAL)

25. CAUSES OF IHD: CIGARETTE SMOKING HYPERTENSION DIABETES MELLITUS
INCREASED LIPIDS ( CHOLESTROL)
OTHER FACTORS: LACK OF EXERCISE, ANXIETY etc.

26. IHD:
IHD IS USED TO DESCRIBE DISCOMFORT IN THE CHEST DUE TO DECREASED CORONARY BLOOD FLOW (TRANSIENT MYOCARDIAL ISCHEMIA).
PATIENT COMPLAINS OF TIGHTNESS OR PAIN IN THE MIDDLE OF CHEST (RETROSTERNAL) FOR FEW MINUTES. PAIN OFTEN RADIATES TO INNER SIDE OF LEFT ARM.
PAIN IS PRECIPETED BY EFFORT AND RELIEVED BY REST.

27. MYOCARDIAL INFARCTION (MI):
IT IS DUE TO OBSTRUCTION TO THE CORONARY BLOOD FLOW, ATLEAST 75 % OF LUMEN OF CORONARY ARTERY IS BLOCKED BY THROMBUS.
MI IS THE COMMEN CAUSE OF DEATH.

28. Applied Aspect
THE C A D.

30. Electrocardiographic changes during exercise test
Electrocardiographic changes during exercise test. Upper trace – significant horizontal ST segment depression during exercise.

31. STEMI CHANGES

32. INVESTIGATIONS: ECG CARDIAC ENZYMES e.g. CK, LDH, TROPONIN etc.
ECHOCARDIOGRAPHY
TREADMILL EXERCISE TEST
THALLIUM STRESS TEST
CORONARY ANGIOGRAPHY
NOTE:
ECG CHANGES IN IHD:
ST DEPRESSION OCCURS IN ECG IN RESPECTIVE LEADS
ECG CHANGES IN MI:
ST ELEVATION OCCURS IN ECG IN RESPECTIVE LEADS

33. TREATMENT: CORONARY DILATORS E.g. NITRATES BETA-BLOCKERS
ANGIOPLASTY (DILATE AREA OF CONSTRICTION)
STENT
BYPASS SURGERY

35. Percutaneous transluminal coronary angioplasty (PTCA)
Percutaneous transluminal coronary angioplasty (PTCA). (a) Coronary angiography demonstrates a severe stenosis in the proximal left anterior descending artery. (b) During PTCA a soft guidewire is passed across the stenosis and then a balloon is expanded that dilates the stenosis. (c) Post-PTC

36. An intracoronary stent.

38. THANK YOU