5-Ischemic Heart Disease

Ischemic Heart Disease

Ischemic Heart diseases can be classified into two main categories Acute and Chronic.

Acute Ischemic Heart Diseases:

1) Unstable Angina Pectoris (sudden Onset Angina)2) Myocardial Infarction: Myocardial infarction can be divided into two subgroups;

ST elevation MI and Non-ST elevation MI. ST elevations refer to a finding on an electrocardiogram (ECG), where the ST segment is abnormally high.

Chronic Ischemic Heart Diseases:

- Stable Angina Pectoris : if a patient underwent a Myocardial Infarction followed by several episodes of Angina or when a partial narrowing of coronary arteries occur without causing Infarction then the patient will experience Angina on effort.

Pathology and Anatomy of the heart:

Four main epicardial arteries supply the myocardium of the heart, and a total occlusion in one of those arteries leads to Myocardial Infarction. The artery that brings the most concern is the one supplying the left ventricular muscle rather than the right ventricular muscle. The left ventricular muscle is the most fundamental muscle of heart, being responsible for about 90% of its function, while the right ventricular muscle is weak, contributing for the remaining 10% of the work. So by Myocardial infarction it usually refers to infarction of the left ventricular muscle.

The two main coronary arteries are the right and left main coronary arteries, they branch directly from the Ascending Aorta at the right and left aortic sinuses respectively.

The right coronary artery doesn’t give rise to other main arteries, only to small branches supplying the anterior wall of the right ventricle. On the other hand,

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the left coronary artery is 1-1.5 cm in length as it branches directly after originating from the ascending aorta. It divides into left anterior descending artery and circumflex artery, both arteries are considered to be significant.

The left anterior descending artery supplies the anterior part of the left ventricle, and the blockage of this artery may induce an Anterior Wall Myocardial Infarction. This artery is also called the Black Widow (poisonous spider) since its acute occlusion is the leading cause of death in males.The circumflex artery supplies the lateral part of the anterior wall of the left ventricle in addition to most of the posterior wall of the left ventricle.

Another important artery is the posterior descending artery; it supplies the posterior wall of the left ventricle. In 70% of the population it branches directly from the right coronary artery, the remaining 30% have it as a continuation of the circumflex artery. So it is not a direct branch from the Aorta.

Any pathological condition causing a thrombus or an acute occlusion in one of those arteries will lead to death/necrosis of the muscle supplied by that artery. The thrombus may not cause complete obstruction but partial narrowing of the artery, it will then result in a non-ST elevated MI.If this narrowing is accompanied by atherosclerosis (accumulation of fats on the inner walls of the vessels) and this narrowing did not exceed 60% it will be asymptomatic. However, if the narrowing surpasses 70%, symptoms will appear with exertion (Angina with effort). If not treated, it may progress to Unstable Angina, where the narrowing has reached 90-95%.

On another scenario, the accumulated plaque may fissure or break through from its position migrating elsewhere in the vessel activating platelets and fibrin causing a thrombus. In this case, Myocardial Infarction may occur. Going back to Ischemic Heart Diseases, the term describes ischemia resulting from decreased perfusion. The word ischemia means lack of oxygenation due to decrease perfusion of blood. It is not confined only to coronary arteries, it might be present in other places in the body ex: mesenteric ischemia and splenic ischemia.


Ischemic Heart Diseases results from imbalance between oxygen demand and supply.

Types of Angina: Angina of effort, Unstable angina, Decubitus angina, Angina crescendo, Prinzmetal angina.

Clinical presentation of ischemic heart disease:

Chest pain Fainting (Syncopy) Arrhythmias Nausea, vomiting or sweating Sudden death Ischemic cardiomyopathy Painless MI (Incidental discovery)

Etiology/ Causes:

Atherosclerosis (~99%): The most common cause. Embolization Coronary spasm Vasculitis Ostial stenosis Severe Left Ventricular Hypertrophy Congenital anomalies of the coronary arteries (e.g anomalous origin of LAD

artery from pulmonary artery) Connective Tissue diseases Syphilis

*Note: Causes other than atherosclerosis rarely cause Ischemic heart disease, and account for about 1% of all the cases.


Risk factors for Atherosclerosis:

*Note: Major factors should be memorized

- Major factors:

Hypertension Diabetes Mellitus Cigarette smoking Hyperlipidemia Positive family history of premature Coronary Artery Disease (CAD): Premature

here means <55yo in males, and <65yo in females. First class relatives (parents, siblings and their children) of the patient with premature CAD should be tested as a precaution. If a male patient is >60yo or a female >70yo CAD is not considered as a risk factor.

-Minor factors:

Aging Male sex Physical inactivity Type A personality High serum urate level Soft water Low high density lipoprotein( HDL) Homocysteinemia High serum fibrinogen level High levels of sensitive CRP


Characteristics of Anginal chest pain:

It is of high importance to be able to clearly differentiate and diagnose the pain as a cardiac ischemic pain (Stable angina, unstable angina or myocardial infarction)

Site of the pain : Typical site is retrosternal area

Radiation : The distribution of cardiac pain is within the areas covered by the nerves originating from C8-T4. Pain may radiate to the anterior neck and the lower jaw (not to upper jaw) causing toothache. It also radiates to the interscapular area, epigastric area, and to the left arm as a whole including shoulder, elbow, inner part of the forearm, and inner fingers.

Quality(character): The most important description is that the pain is Heavy in nature, the patient will complain of heaviness, pressure and compassion on the chest. Other patients may experience burning, stabbing, or catching sensations but are not as significant in diagnosis as the heaviness.

Associated symptoms : Nausea, excessive sweating, and cold sweat. Vomiting once or twice is a strong indication for some types of Infarctions, but not Angina. However, repetitive vomiting is a symptom of local gastric diseases (ex: gastritis) and never a symptom of Infarctions

Relieving factors and duration of pain : It is important to know if the pain is continuous, intermitted, or recurrent. Angina with effort lasts for about 2-3 minutes, it subsided with rest or sublingual nitrates. In, Unstable Angina, the pain is continuous and more prolonged, lasting from 5 to 15 min. if the pain lasted for more than 30 min, the cause is probably MI. Pain due to MI will not subside with rest or sublingual nitrates, it requires strong IV analgesia (morphine or other synthetic opioids).

Precipitating factors : only in chronic Anginal pain, because acute angina pain, like any other acute condition, occurs suddenly. Factors include: rapid arrhythmias, BP crisis, severe anemia, acute stress, strenuous efforts, walking up a hill in cold weather, large meals, coitus, hypoxia, hypoglycemia.


Diagnosis:

To establish a complete diagnosis history of the patient must be taken, in addition to physical examinations. Tests could also include:

ECG: To examine Q waves, ST segments ECG might probably appear normal, and it’s a fatal mistake to send a patient home after a normal ECG when we are suspecting IHD and a treadmill test is performed.

Cardiac enzymes: Troponin I, Troponin T, total CPK (Creatine PhosphoKinase) and CK-MB (Creatine Kinase Myocardial Band)

Chest x-ray FBS Serum lipids TMT Stress or pharmacologic stress myocardial perfusion studies Coronary angiography

History taking is very important for diagnosis because it might give us many clues about IHD especially when the facility is limited and many tests might not be available. So a clue from the patient’s history is sufficient for hospital admission.

As a dentist history taking in such conditions is essential, because a patient on the dental chair might experience Anginal pain. In this case the dentist should be fully prepared for action. The patient must immediately be given sublingual nitrates in the sitting resting positions, and referred directly to his/her physician. It is not a requirement for the dentist to perform sophisticated test Ex: ECG but rather leave it to the specialist.

Differential diagnosis of chest pain (Mentioned briefly)


Myocardial ischemia Pericarditis Pleurisy PE, Pneumothorax,

Tracheobronchitis, Mediastinitis, Mediastinal emphysema

Aortic dissection Costo-chondritis (Teitz syndrome) Cervical spondylosis Herpes Zooster infection Pleurodynia (Bornholms disease)

Thoracic outlet syndrome (Cervical rib, Scalenus anticus muscle syndrome)

Esophageal disorders(Reflux esophagitis, esophageal spasm)

Peptic ulcer disease Localized breast disorders Metastatic rib lesions Efforts syndrome (Hyperventilation

syndrome) Muscular catch syndrome

Studies showed that 70% of admitted patients with chest pain were suffering from non cardiac chest pain. However cardiac disorders (Ex: Heart Attack) should be excluded before investigating in other causes of the pain

*Note: Treatment details were not mentioned in the lecture.

Treatment of Angina Pectoris

Nitrates Beta-blockers Aspirin CCB (in coronary spasm) Treating the associated risk factors Treating the precipitating factor Revascularization (if indicated)

Treatment of Unstable Angina

Admission to hospital Aspirin Beta-blockers Anticoagulants CCBs (in case of coronary spasm) Nitrates Revascularization (PTCA or CABG if

indicated)

Done by: Raya Dawood & Lama Ashour.


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5-Ischemic Heart Disease