CORONARY ARTERY DISEASE

INTRODUCTION

• Coronary artery is a type of blood vessel disorder that is included in the general category of atherosclerosis. The atherosclerosis begins as soft deposits of fat that hardens the arteries.
• Coronary Artery Disease (CAD) happens when the arteries that supply blood to heart muscle become hardened and narrowed. This is due to the build-up of cholesterol and other material, called plaque, on their inner walls called as atherosclerosis. As it grows, less blood can flow through the arteries. As a result, the heart muscle cannot get the blood or oxygen it needs.
•  This can lead to chest pain (angina) or a heart attack. Most heart attacks happen when a blood clot suddenly obstructs the hearts' blood supply, causing permanent heart damage

ETIOLOGY

NON-MODIFIABLE RISKFACTORS

• Age: more common in over 65 years age
• Gender: more common in men when compared with women
•  Ethnicity: white and middle aged men and ethnic group of Americans have higher incidence of CAD
• Genetic predisposition: family history of CAD and Hyper cholestrolemia plays an important role in developing CAD.

MODIFIABLE RISK FACTORS:

• Hypertension: Increased Blood pressure can cause constant pressure to the walls of the arteries leading to Vascular endothelial Injury leading to Atherosclerotic lesions in the intimal walls of the arteries
• Obesity: Fat deposits of cholesterol or lipids in the intimal wall of the artery can attract platelets and Vasoactive substances that can predispose to formation of plaque in the walls of the Arteries
• Habits: Tobacco, Alcohol & Smoking leads to vasoconstriction and disrupt the blood flow to the heart
• Hyper lipidemia: can cause fatty deposits in the walls of the arteries and predispose to Atherosclerotic plaque formation
• Diabetes mellitus: Increased Glucose levels can cause endothelial injury of the coronary arteries predisposing to formation of atherosclerotic lesion and decreased coronary blood flow
• Life style: Sedentary lifestyle like Physical Inactivity and over eating especially junk foods can lead to atherosclerosis of coronary arteries
• Infections: Chlamydia, pneumonia, herpes etc. can cause endothelial injury of blood vessels leading to complex vascular lesions and inflammation to the blood vessels predisposing to CAD
• Emotional states: Psychologic Stress, Anxiety, Panic, grief can trigger various vascular endorphins and chemical mediators that predispose to development of Atherosclerotic lesions & Vasoconstriction leading to CAD

CONTRIBUTING FACTORS:

• Increased Homocysteine Levels triggers increased HMG CoA  reductase activity & certain Inflammatory mediators causing cholesterol synthesis causing hyperlipidemia & believed to be a Contributing factor of CAD
• Metabolic Syndrome causes dyslipidemia and Obesity can lead to CAD
• Menopause & Use of Oral Contraceptives causes decreased estrogen levels and increased cholesterol synthesis can predispose to CAD

PATHOPHYSIOLOGY:

CLINICAL MANIFESTATIONS

• Pain: severe, immobilizing chest pain, Pain is described as a heaviness, pressure, tightness, burning, constriction or crushing.

PAIN ASSESSMENT

• P- precipitating factors (eg. Exercise, resting)
• Q- Quality of pain (eg. Pressure, dull, tight, squeezing)
• R- Radiation of pain (Does pain radiate to other areas like back, arms, jaws, teeth, shoulder, elbow)
• S- severity of pain (rate pain in a scale of 0 to 10)
• T- Timing of pain (when did pain begin, pain changed since time, have you had pain like this before)

TYPES OF ANGINA PECTORIS

• Angina Decubitus or Nocturnal angina: It is angina that occurs in the night while the patient is in recumbent position.
• Stable Angina: It is the chest pain that occur during physical exertion or emotional stress.
• Unstable Angina: It is the chest pain that occur even while resting.
• Prinzmetal Angina or variant angina: this occurs when there the person is at rest usually between midnight and early morning.

SIGNS & SYMPTOMS OF CORONARY ARTERY DISEASE (CAD)

• Difficulty breathing or shortness of breath
• Sweating or "cold sweat"
• Fullness, indigestion, or choking feeling (may feel like "heartburn")
• Nausea or vomiting
• Light-headedness, dizziness, extreme weakness or anxiety
• Hypertension: Increased Blood Pressure
• Tachycardia: Rapid & irregular heart beats

DIAGNOSTIC FINDINGS:

• History collection regarding Age, Gender, ethnicity, Family history, Lifestyle, Habits etc
• Physical Examination elicits the presence of Chest Pain, Palpitations, tachycardia, Hypertension etc.
• Lab Investigations: Complete Blood Count (CBC) to identify anemia
• ECG reveals ST segment elevation
• Serum cardiac markers shows CK, CK.MB, Troponin elevated.
• Chest X-ray: to identify ventricular hypertrophy and cardiac size
• Echocardiogram: To identify the ventricular function.
• Serum lipid profile to identify atherosclerosis
• Coronary angiogram to confirm the obstruction of Coronary Arteries.

MEDICAL MANAGEMENT:

• Inj. Morphine sulfate IV to relieve pain
• Oxygen therapy to increase myocardial perfusion.
• Inj. Nitroglycerine IV for vasodilation
• Anti-Coagulant therapy- Ecosprin, Clopidogrel
• Continuous monitoring of vital signs and pulse oxymetry.
• Provide complete bed rest.
• Fibrinolytic therapy: Inj. Streptokinase 1.5 million units IV for one hour.
• Β- Adrenergic blockers like esmalol, propanalol to treat Hypertension.
• Antiarrhythmic drugs like Cordarone 100mg IV.
• Anti platelet therapy: Inj. Heparin can be administered to prevent clot formation.
• Lipolytic agents: statins include atorvastatin (Lipitor), fluvastatin (Lescol XL), lovastatin (Altoprev), pitavastatin (Livalo), pravastatin (Pravachol), rosuvastatin (Crestor, Ezallor) and simvastatin (Zocor, FloLipid) can be administered o reduce cholesterol level.
• Stool softeners like Docusate sodium for bowel evacuation.

INTERVENTIONAL THERAPIES:

• Percutaneous trans luminal coronary angioplasty (PTCA):

      It is a minimally invasive procedure to open up blocked coronary arteries, allowing blood to circulate to the heart muscle. It is accomplished with a small balloon catheter inserted into an artery in the groin or wrist, and advanced to the narrowing in the coronary artery. The balloon is then inflated to enlarge the narrowing in the artery.

• Intra Coronary Stents:

It is a non-surgical procedure that uses a catheter (a thin flexible tube) to place a small structure called a stent to open up blood vessels in the heart that have been narrowed by atherosclerotic plaque. A stent is an expandable mesh like structure designed to maintain vessel patency by compressing the arterial wall and preventing vasoconstriction.

• Trans Myocardial Laser Revascularisation (TMR):

It is for patients who cannot undergo traditional bypass surgery and this involves high laser energy is triggered to create channels between the left ventricular and coronary micro circulation. This allows blood flow to the ischemic areas. And this procedure performed through cardiac catheterization.

SURGICAL MANAGEMENT:

• Coronary artery bypass graft surgery:(CABG)

 This procedure is done by construction of new conduits to transport blood between aorta or major arteries.

 It is done by obtaining one or more grafts usually taken from saphenous vein, internal mammary artery, radial artery and Epigastric artery.

• Minimally invasive direct Coronary Artery Bypass (Mid-CAB)

This technique offers the patient with single vessel disease and does not need sternotomy and cardio pulmonary bypass. This technique several small incisions between the ribs a thorocoscope is used to dissect internal mammary artery and this sutured to the coronary artery.

• Off Pump Coronary Artery Bypass:

This procedure done by a full or partial sternotomy to access all coronary arteries. This procedure is performed on a beating heart and without cardio pulmonary Bypass.

TREATMENT OF UNSTABLE ANGINA AND NON-ST SEGMENT ELEVATION MYOCARDIAL INFARCTION (MI)

• Drug treatment with nitroglycerine to treat angina
• Low molecular weight heparin, clopidogrel and glycoprotein IIb, IIIa inhibitor (intergrilin) to treat emboli formation by dissolving the clot
• Coronary angiography with percutaneous coronary interventions to aid in coronary vascularization.

TREATMENT OF ST SEGMENT ELEVATION MYOCARDIAL INFARCTION (MI)

• Percutaneous coronary interventions to increase myocardial perfusion
• Emergent CABG surgery to aid myocardial revascularization
• Fibrinolytic treatment: streptokinase 1.5 million units is administered slowly over 1hr after getting the baseline laboratory investigations like cardiac enzymes, ECG. While the procedure is done patient is continuously monitored for ECG changes, BP, SPO2. This helps to destroy the clot and helps reperfusion of the myocardium

NON-INVASIVE TREATMENT:

Enhanced External Counter Pulsation (EECP): It is performed as a non-invasive treatment to reduce the number and intensity of angina episodes. Treatment is administered through three pairs of external inflatable cuffs that are applied around the lower legs, upper legs and buttock. These cuffs continuously inflate and deflate between the resting period of the heartbeat and increase blood returned to the heart.

PATIENT TEACHING:

• Strict Hypertension control with Anti-Hypertensive drugs
• Diabetic control with Insulin Therapy & Oral Hypoglycemic Agents
• Control of Elevated serum lipids with Exercise regimen
• Habitual Changes as Avoid Tobacco use, Cessation of Smoking & Limitation of Alcohol.
• Physical activity: Brisk walking 30 minutes a day for at least 5 days a week
• Management of Stressful lifestyle by Yoga, meditation, prayers. 
• Control of Obesity with dietary Modification.