Ischemic Heart Disease Overview

Ischemic Heart Disease

• Is a condition where blood supply to the heart muscle (myocardium) is reduced due to narrowing or blockage of the coronary arteries.
• Two types: Chronic coronary syndrome and Acute Coronary syndrome
• A 60-year-old male smoker with diabetes presented with retrosternal chest pain (heavy) lasting about 5 minutes, brought on by exertion and relieved by rest. This is a typical presentation of stable angina.

Cardiovascular Disease Worldwide

• Cardiovascular disease is the leading cause of death worldwide, even more so than cancer and other diseases.
• In 2002, cardiovascular disease accounted for 29% of global deaths.

Heart Anatomy

• The heart is about the size of a fist and weighs 300-450 grams.
• Average heart beats per minute is 70 (60-100 bpm).
• An average adult heart pumps 6000-7500 liters of blood per day (70ccx70x60x24).
• The heart receives blood supply primarily from two coronary systems, one on the left (left coronary artery) and one on the right. The left artery branches into the left anterior descending artery and circumflex artery.

Coronary Circulation Physiology

• Basal cardiac circulation flow: 70-80 ml/min/100 gm (increases up to 8 times during exercise).
• Maximal cardiac work flow: 300-400 ml/min/100 gm (needed to meet the increased demand).
• High oxygen extraction: 65-75% (fixed), unlike skeletal muscles' extraction which depends on exercise state.
• 80% of coronary flow occurs in diastole, unlike other organs (brain's blood supply occurs in systolic phase).

Stable Angina

• Commonest form of angina, caused by an imbalance between oxygen supply and demand.
• Location: central chest, radiating to the arms, neck, jaw, or teeth.
• Characterized by squeezing, pressure, or heaviness.
• Duration: 2-10 minutes.
• Relieved by rest or nitroglycerin.
• Precipitated by exertion, emotional stress, heavy meals, or sexual activity.

Acute Myocardial Infarction (AMI)

• The most common cause of death due to ruptured atherosclerotic plaque leading to coronary occlusion.
• Clinical manifestations: Chest pain that lasts persistently for over 30 minutes( often at rest).
• Pain may radiate to the neck, teeth, jaws, or trans shoulders or epigastrium.
• Associated symptoms: nausea, sweating, or vomiting, dizziness, and shortness of breath.

Diagnosis of Stable Angina

• History and physical examination.
• Electrocardiogram (ECG) (normal does not rule out ischemic heart disease).
• Stress ECG (diagnostic and prognostic information).
• Radioisotope studies (thallium scan).
• Echocardiography.
• Coronary angiography.
• Blood tests (serum lipids, e.g., LDL, HDL, TG, FBG, CBC).

Management of Stable Angina

• To improve prognosis (mortality reduction) via modification of risk factors.
• Use of lipid-lowering therapy (statins).
• Aspirin.
• ACE inhibitor.
• Revascularization procedures (PTCA or CABG).
• To decrease anginal symptoms via medical treatment, e.g., beta-blockers or nitrate.

Treatment of Myocardial Infarction

• In the emergency room--time is muscle.
• Rapid assessment and examination.
• Establish IV access.
• 12-lead ECG.
• Aspirin 150-300 mg orally, clopidogrel 300 mg orally.
• Oxygen: nasal cannula 2-4 l/min.
• Analgesia: IV morphine, diamorphine 3-5 mg.
• Antiemetic: metoclopramide 10 mg IV.
• Sublingual nitrate – if NO hypotension, RV MI.
• Beta-blockers if ongoing chest pain, hypertension, tachycardia.
• GP IIb/Illa inhibitor.
• ECG monitor.
• Reperfusion: PCI or Thrombolytics.

Prognosis of MI and Stable Angina

• Pre-hospital mortality: ~20%
• Hospital mortality: 10-12%
• Prognosis for Stable Angina depends on the number and site of affected vessels.
• Prognosis for MI depends on several factors, including heart failure, large infarction size, left main stem involvement, new BBB, Mobitz type 2 or 3, AV block, frequent PVCs, VF or VT, atrial fibrillation, post-infarction angina, diabetes, age over 70, and female gender.

Dentist and IHD Patients

• Avoid tachycardia (adrenaline).
• B-blocker should not be stopped abruptly, to avoid rebound tachycardia.
• Antiplatelets (type, and half-life).
• Anticoagulant.