CAD and MI
Coronary Artery Disease CAD and Myocardial infarction MI
Coronary Artery Disease is a heart condition that is widely prevalent and well known. It affects upto over half of middle aged men and over a third of middle aged women. Upto 8% of our population has been found to have some form of this condition.
Aside from genetic risk factors, Diabetes, Hypertension and smoking are major players in coronary artery disease. Obesity, inactivity, excess alcohol intake, and high cholesterol add to the disease burden.
Usually presenting as chest pain or angina, and progressing to heart attacks or myocardial infarction, the underlying problem lies in the blood supply to the heart muscles. The blood vessels or coronary arteries supplying the heart wall muscles can be narrowed or blocked over time by build up of cholesterol plaques, which can sometimes rupture or crack exposing the underlying lining of the vessel walls to the circulating clotting factors and platelets. This initiates a clotting process and build up of sticky platelets and a fibrin meshwork that limits the flow of blood in the vessel to the heart muscles, leading to angina or chest pain. When the vessel is completely occluded or blocked the heart muscles suffer injury and muscle death, leading to myocardial infarction or a heart attack.
Depending on the size of muscle involvement, this may result in poor heart pumping ability and further drop in the output of vital blood supply to organs, including the heart itself, the brain, kidneys, and lungs, etc. Due to pooling of venous blood as result of poor heart pumping action, a backup of fluid occurs in the lungs resulting in shortness of breath and an emergent respiratory condition better known as pulmonary edema. Similarly feet swelling or pedal edema and liver enlargement leading to abdominal pain can also occur. These features of heart failure can be telltale signs that one’s heart is under functioning and may have suffered an injury due to lack of blood supply.
Due to pain signals released by heart muscle or myocardium at risk, patients quickly seek medical attention during a heart attack. Unfortunately, in those with diabetes the pain signal may be subdued by poorly functioning nerves and they may therefore present with silent heart attacks without the typical angina pain. Instead they can present solely with exercise intolerance, chest pressure and shortness of breath. Exacerbating factors include strenuous unaccustomed activity, cold weather, heavy meals, and early am diurnal effects.
Angina or chest pain is difficult to describe but can present as a severe chest discomfort, tightness or burning, often times with a heavy pressure like discomfort, with difficulty breathing, and jaw pain radiating down the left and occasionally bilateral arms. Nitroglycerin 0.4mg sublingual taken immediately usually relieves angina and can be helpful in diagnosis, (though can also relieve esophageal spasm pain). It limits the injury temporarily allowing more blood supply thus buying precious minutes before the patient can receive more definitive medical attention. An aspirin can also help prevent newer clots from worsening the narrowing taken at the time of a heart attack. If someone is suffering signs of angina or a heart attack they need immediate medical attention and it is imperative to activate 911 or emergency medical response teams. Heart attacks can lead to immediate development of life threatening cardiac arrhythmias or rhythm disorders including rhythm blocks leading to loss missed or stopped beating of the heart or cardiac arrest leading to sudden cardiac death.
Once in medical care, the treatment consists of stabilizing the person by providing immediate support to breathing, blood circulation, and immediate administration of nitroglycerin, aspirin, oxygen to supplement the ailing heart, and pain control with morphine to avoid the overdrive and strain of the heart due to response to pain. Immediate cardiac catheterization is indicated in many patients depending on their presentation to allow visualization of the site of blockage.
The blood supply to the heart consists of three major vessels, the most important being the LAD or Left anterior or main descending artery, the circumflex artery, and the RCA or Right coronary artery. The LAD supplies the majority of the heart including the front and apex of the heart. The RCA provides supply to the back of the heart and also to the all important AV atrio ventricular node which conducts impulses from the atrium to the ventricles.
Not all chest pain is however from the heart, and mimics need to be carefully excluded to avoid harmful cardiac testing. Musculoskeletal chest pain, costochondritis, esophageal spasms, gastric ulcers and gastritis related pain are common confounders. The below tests help.
Testing include serial blood tests for cardiac enzymes including Creatine Kinase (CK) and CKMB ( more specific to cardiac muscles), Troponins which leak into the blood stream when the muscles are damaged. Bedside EKG or electrocardiograms are also done in the ambulance or in the ER. Telltale signs of a heart attack include changes in the EKG waveforms showing rhythm disturbances, ST depression, ST elevations and presence of Q waves in that order. Other chronic features may be evident from an EKG including older areas of heart damage, and heart hypertrophy due to long standing uncontrolled high blood pressures.
Non invasive testing is undertaken in stable patients. Cardiologists or heart specialists usually assess and determine the appropriate testing required.
Tread mill testing takes place under the supervision of a cardiologist in which the patient is made to exercise on a treadmill to a target heart rate to assess and EKG changes.
In those unable to exercise due to physical limitations, pharmacologic or drug stress testing with persantine can be performed.
Dobutamine or exercise stress echocardiograms are another effective modality.
Nuclear stress tests are also available to assess blood supply to heart muscles.
Finally newer imaging modalities including CT angiography and MR cardiac angiography are available to assess the coronary vessels.
Echocardiograms or ultrasounds of the heart allow functional assessment of the pumping action and the three valves ( aortic, mitral and tricuspid valves) in the heart.
Invasive testing is done with cardiac catheterization to assess the blood flow in the coronaries supplying the heart. This allows for accurate imaging of the vessels to allow a diagnosis of any blockages and possibly intervening at that time by balloon angioplasty in which the vessel walls are stretched wider followed by placing stents that allow the vessel to remain expanded preventing them from collapsing or closing off. Drug eluting stents may provide better protection than bare metal stents in terms of need for revascularization. If multiple vessels are narrow in many regions or blocked in a complex manner or the left main vessel is affected proximally or in certain diabetics and those with poor cardiac functional status, Coronary Artery Bypass Grafting or CABG surgery may be considered.
Medical management consists of the above procedures followed by certain long term goals. Usually an antiplatelet agent along with a heart rate slowing agent such as a beta blocker are indicated for prevention of further heart attacks. Medications for angina rescue are also provided including nitroglycerin sublingual tablets. Appropriate risk factor modification would include lifestyle changes including weight loss, exercise, healthy diets, smoking cessation and management of any other conditions including diabetes, hypertension, high cholesterol, etc.
Tips for Coronary Artery disease
Healthy activity and cardio workouts. Get on a Stationary Exercise Bike
Healthy Cardiac Diet 
Healthy sleep, including assessing for sleep apnea. Consider a White Noise Sleep Device
Weight loss and maintenance of appropriate body weight. Consider a good bathroom weighing scale
If you're serious about your health and want to take charge consider investing in a device called FITBIT
Management of all underlying risk factors
Smoking cessation
Antiplatelet therapy with Aspirin or plavix (clopidogrel) etc
Beta blockers (Atenolol or metoprolol,etc) to slow down the heart rate and avoid cardiac exertion.
ACE inhibitors for blood pressure control are of added benefit to heart conditions.
Low salt diet. (<2400mg/day)
Regular check ups
Keeping Aspirin and nitroglycerin handy at all times
Avoiding excess alcohol use
And finally treating any inflammatory conditions, gout, etc are important in prevention of CAD.
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