Coronary artery disease

Coronary arteries supply blood for heart’s energy needs and nourishment  Three main coronary arteries: Right Coronary artery Left anterior descending coronary artery Left circumflex

Coronary Artery

Disease

Mariano B Lopez, MD, FPCP, FPCC

Anatomy of the Heart

 Heart is a muscular organ with four chambers

and valves Chambers pump blood through the body.

Right & Left Atria  Tricuspid & mitral valves

Right & Left Ventricle  Pulmonary & Aortic valves

 Heart muscle needs steady supply of oxygen and nutrients Coronary arteries supply blood for heart’s energy needs and nourishment

 Three main coronary arteries:

Right Coronary artery

Left anterior descending coronary artery

Left circumflex coronary artery

Blood distribution of the

coronary arteries

LEFT CORONARY

ARTERIES

 THE CIRCUMFLEX CORONARY

ARTERY COURSES ALONG THE

CORONARY SULCUS

(SEPARATING THE ATRIUM

FROM THE VENTRICLES)

TOWARDS THE LEFT AND

AROUND THE LEFT BORDER OF

THE HEART

RIGHT CORONARY

ARTERIES

 IMMEDIATELY AFTER

EMERGING FROM THE

CORONARY SINUS IT GIVES OF

A BRANCH TO THE SINO-ATRIAL

NODE (SA NODE ARTERY)

 COURSES IN THE DEPTHS OF

THE CORONARY SULCUS

 DIVIDES INTO A MARGINAL

BRANCH AND A POSTERIOR

INTERVENTRICULAR BRANCH

What is Coronary Artery Disease?

Narrowing of heart’s coronary arteries

Majority of CAD due to atherosclerosis

Heart muscle with insufficient oxygen

because blood flow is decreased due to

narrowing of these arteries (ischemic heart disease)

Total lack of oxygen supply to heart muscle (myocardial infarction or heart attack)

Pathogenesis of atherosclerotic plaques

Protective response results in production of

cellular adhesion molecules

Monocytes and T lymphocytes attach to

‘sticky’ surface of endothelial cells Migrate through arterial wall to subendothelial space

Lipid-rich foam cells Endothelial damage

Macrophages take up oxidised LDL cholesterol

Normal arterial wall

Tunica adventitia Tunica media Tunica intima

Endothelium Subendothelial connective tissue

Smooth muscle cells Internal elastic membrane

Elastic/collagen fibres

External elastic membrane

Development of atherosclerotic plaques

Atherosclerosis

Growth mainly by lipid accumulation Thrombosis, hematoma

Adapted from Stary HC et al Circulation 1995;92:1355-1374.

Libby Circulation 1995;91:2844–2850.

– T lymphocyte – Macrophage foam cell (tissue factor + )

– “Activated” intimal SMC (HLA-DR + )

– Normal medial SMC

Fibrous cap Media

Lipid core

The stable atherosclerotic plaque

Thick, VSMC- rich

fibrous cap

Thin Fibrous Cap

Lipid Core

Unstable Plaque

Unstable Angina With Plaque

Disruption

Davies Atlas of Coronary Artery Disease Lippincott-Raven, Philadelphia, Pennsylvania: 1998:81

Thrombus InflammatoryCells

FewSMCs

ActivatedMacrophages

Ruptured Plaque

Angiography of Unstable Angina

Davies Atlas of Coronary Artery Disease Lippincott-Raven, Philadelphia, Pennsylvania: 1998:79

Signs and Symptoms of Coronary Artery disease

No symptoms

Angina pectoris

Chest pain, compressing &

substernal, lasting for 5- 15 minutes,

Signs and Symptoms of Coronary Artery disease

Heart Failure Signs- neck vein engorgement,

rales, large liver and bipedal edema

Risk factors for CVD

– Gender

Levels of risk associated with smoking, hypertension and hypercholesterolaemia

Diagnostic Tests For CAD

Recording of electrical changes in the heart

 Cardiac cell stimulation generates electrical activity

Electrodes placed on arms and legs ( limb leads) and on chest ( chest leads)

EKG tracings can determine the following

 abnormality in conduction pathway

 enlargement of heart

 damage to certain regions of heart

 1) small downward wave

 2) big upright wave

 3) small downward wave

 represents electrical stimulation of ventricles

T wave

 upward wave that represents ventricular relaxation

P

Stress Tests

Various tests to determine

the heart capacity to tolerate

physical or pharmacologic

stress

Treadmill stress test

 Pharmacologic Stress test

Stress tests with imaging

Use to diagnose ischemia

(CAD) during stress

conditions

Utilize sound waves to

produce an image of the

heart in motion

Diagnosis of CAD based

on findings of wall motion

Nuclear Scans

Trace amounts of radioactive dye, either thallium or technetium, are injected into the bloodstream into the coronary

arteries

Special cameras can detect areas of

less blood flow (perfusion) signifying the site of coronary occlusion

Coronary Angiography

Definitive test for coronary

artery disease

Small tube (catheter)

inserted into artery in the

arm or groin and threaded to

the heart

A dye (contrast agent)

injected into the catheter As

dye flows through the

coronary arteries, specific

sites of narrowing in the

coronary arteries are

visualized

Electron-Beam Computed

Tomography (EBCT)

Special test using advanced CT- scans

to detect the presence of calcium within the atheromatous plaques

Presence of substantial amount of

calcium in the coronary artery is

associated with presence of significant coronary artery disease

Management of Coronary Artery

ASA, BB, CCB, Nitrates, ACEI,

lipid-lowering agents and other

Medications used for the treatment and/or prevention of Coronary Artery Disease

Drugs Mechanism of

Action Effects

Aspirin (ASA) blood clot formation in

the artery  risk of heart attack /stroke

Calcium Channel

Blockers Coronary dilation;  BP & /or  HR flow to heart muscle;

cardiac work Nitrates Coronary dilation flow to heart

muscle ACE Inhibitor  Angiotensin II

atheroma &  BP

cardiac work

flow to heart muscle

Lipid-lowering agents  Cholesterol

atheroma

flow to heart muscle

Medications proven to improve clinical outcomes and/or survival in coronary

Evidence-based trials on Aspirin

34% MI &

sudden death

events.

Aspirin 75 to 325 mg daily should be used routinely in all patients

with acute & chronic ischemic heart disease with or without

manifest

symptoms, in the absence of contraindications

ACC/AHA CSAP Guideline

JACC 1999; 33(7) : 2137

Evidence-based trials on Beta-blockers

28% sudden death 23%  nonfatal re-

MI & CAD death

44% combined death, VT/VF, MI, hospitalization, angina,& revasc Longer time to 1 st

event

Evidence- based trials on Statins

Baseline TC 212-308 mg/dl

30-35%  mortality rate and major CV events.

Chol & Recurrent

Events (CARE)

N Engl J Med 1996;

335: 1001-9

Previous MI 3-20 mo (4,159pts)

Baseline TC <240 mg/

dl and LDL 115-174 mg/dl

24%  fatal/ nonfatal MI

Long term Interv

TG <445mg/dl

22% total mortality 24% CAD mortality 25% CV mortality 29% MI

Evidence-based trials on Fibrates

dyslipidemia (HDL

40 mg/dl, LDL  140 mg/dl & TG

300mg/dl)

2,531 patients given gemfibrozil or

placebo

Follow up period:

5.1 years

24% CAD death, stroke or nonfatal

MI

23% CAD death or nonfatal MI

ACC/AHA CSAP Guideline JACC 1999; 33(7) : 2137

Evidence-based trials on ACE

25% CV deaths 24% sudden death

(5w)

Heart Outcome

Prevention

Evaluation (HOPE)

N Engl J Med Jan2000

High risk for major

CV event: Hx of CAD, PVD, stroke

or DM+ 1 RF (9,297 pts)

22% combined CV death, MI or stroke 16% total mortality

Evidence-based trials on Nifedipine & Verapamil

 Nonfatal MI (5.1% vs 4.2%)

Danish Study group on

Evidence-based trials on Diltiazem

11%  fewer first recurrent cardiac events (CV deaths / nonfatal MI)

No change in mortality

 Cardiac events on patients with LV dysfxn

Evidence-based trials on Diltiazem

63%  refractory angina60%  ref Angina & MI Improved event-free survival

Not yet available

Evidence-based trial on Amlodipine

Amlodipine 5-10 mg OD

vs placebo (3 years)

No differential effect on coronary artery lesion (QCA);

carotid IMT (-mode US)

No effect on mortality or major CV events

35%  unstable angina & HF

43%  PTCA / CABG

Catheter with small balloon tip

threaded to coronary occlusion;

balloon inflated to widen the

artery and improve blood flow;

At times, stents (small wire

tubes) are placed to keep artery

from narrowing again

Coronary Artery Bypass Grafting (CABG)

Reserved for severe cases of coronary occlusion

Under general anesthesia, small blood vessel from leg or chest used as the “bypass graft” The graft connects one end to the aorta and the other end to the coronary artery beyond the narrowed area

Percutaneous Transluminal Coronary Angioplasty (PTCA)

PTCA with stent implantation

Coronary Artery Bypass

Grafting (CABG)