Pathophysiology & Pharmacology of Cardiac Disease


The Heart

The heart is a muscular organ the size of a fist, whose function is to continuously pump blood around the body. It is located in between the lungs, towards the left side of the chest. In humans, it is divided into four chambers. The heart pumps blood with a rhythm known as the heartbeat. A healthy human heart beats about 72 times per minute. The heart receives deoxygenated blood from the systemic circulation, which enters the right chamber through the superior and inferior venae cavae and is passed to the right ventricle. It then goes to the lung where it is oxygenated. The oxygenated blood returns to the left atrium, passes through the left ventricle and is returned to the systemic circulation through the aorta. This process is called the blood circulation. The networks of blood vessels that circulate blood within the heart are called coronary arteries. The chambers of the heart pump blood through systolic and diastolic action. During systole, cardiac muscles contract to push blood out of the chamber, whereas during diastole cardiac muscles relax so that the chambers may allow in blood.

Pathophysiology of Ischemic Heart Disease

Ischemic heart disease or coronary heart disease is a leading cause of death among adults in developed countries. Ischemic is a medical term which means ‘reduced blood supply’. Ischemic heart disease is a condition that causes a disproportion between myocardial supply and demand of oxygen, due to the atherosclerosis of the coronary arteries. Atherosclerosis is the narrowing and hardening of arteries due to the build-up of fat and cholesterol, otherwise known as plaque or atheroma, within them, leading to the destruction of the endothelium. Due to the inadequate oxygen in the heart, ischemic heart disease usually results in accumulation of waste metabolites and myocardial hypoxia.

Symptoms of Heart Disease

Common symptoms of ischemic heart disease include; fatigue and weakness, an irregular pulse and chest pain accompanied by shortness of breath and dizziness; depending on the severity, the chest pain may also radiate to the arms, neck, jaw, and back.  The chest pain is a major symptom and is medically referred to as angina. It may feel like intense heartburn. However, the disease may also be symptomless in some cases, and only be detected following a heart attack or heart failure.

Risk Factors

Risk conditions that may lead to Ischemic heart disease include; being overweight or obsess, aging, genetic factors, hypertension, diabetes mellitus, smoking, high cholesterol levels and stress. Recent clinical angiographic, scintigraphy, hemodynamic and animal studies reveal that the increase of vasomotor tone is also a cause of ischemic heart disease. Diagnosis includes learning more about the patient’s family and medical history and their lifestyle. The more sedentary one’s lifestyle is, the higher their chances of contracting a coronary illness. Apart from finding out about the patient’s medical and family history, various tests are also carried out to establish the presence of ischemic heart disease. These are; a CT scan, an MRI scan, treadmill test, radionuclide scan and a coronary angiography.

Pharmacology of Ischemic Heart Disease

Treatment for ischemic heart disease includes; medicine – medical treatment comprises a combination of nitrate, β-blocker, lipid-lowering medication and aspirin for blood-thinning. Angioplasty through balloons and stents to widen the narrowed arteries, surgery to widen clogged arteries and, most importantly, making impactful lifestyle changes such as exercising regularly, weight management and eating a healthy diet. (Arora, 2009).

Hypertension and Coronary Diseases

Hypertension is a condition where there is persistently high pressure in the blood vessels. Epidemiological studies show that there is a positive relationship between hypertension and cardiovascular diseases. One of the major long-term effects of this condition is damage to the blood vessels; which results in ischemic heart disease. Amanda is hypertensive and from her BMI of 28, we deduce that she is overweight. Hypertension leads to coronary disease because it causes blood vessels to become narrow, and therefore clog or weaken. Additionally, an elevated BMI is also directly linked to both hypertension and heart disease. In Amanda’s case, there are two factors that increase her risk of developing ischemic heart disease; her weight and hypertension. The ideal BMI of a healthy individual should be between 18.5 and 24.9. Controlling the risk of developing ischemic heart disease will be three-fold. Firstly, Amanda needs to manage her weight through observing a healthy diet and regular exercise in order to obtain a BMI of 24.9 or less. Secondly, assuming that she works as a teller in a busy bank, she needs to take on less demanding duties. Thirdly, she needs to control hypertension through medication. She is already taking Avapro, which is an angiotensin II receptor antagonist that is used in the treatment of high blood pressure. Avapro controls hypertension by blocking angiotensin II and thereby relaxing the blood vessels and preventing them from becoming narrow. She should also ensure that she does not skip a dose and takes the medication at the same time every day.

 Diabetes Type II and Implication on the Health of the Heart

Jim is 43 years old and three years ago was diagnosed with both diabetes type 2 and atherosclerosis. Type II diabetes is a multifaceted disorder that is complicated even further by its cardiovascular implications. (Barnett, O’Gara, 2003). Diabetes is a powerful risk factor for ischemic heart disease. Medical research has discovered that type 2 diabetes sharply exacerbates atherosclerosis by causing inflammation of arteries and slowing the flow of blood. When one has diabetes type 2, there is an accumulation of sugar in the blood due to the cells inefficiency in digesting dietary sugar. The accumulation of sugar in the blood causes the production of highly reactive radicals that destroy cell components and therefore causes the death of the cells. Subsequently, this reduces nitric oxide (NO). Reduction of NO is detrimental to the body because it is responsible for the vasodilation of blood vessels and thus enhances the smooth flow of blood. Insulin is crucial in the management of Diabetes because it stimulates the production of Nitric Oxide. Studies show that atherosclerosis is the cause 80% of the death of diabetes patients. (Beckman, Creager, Libby, 2002).

Lipitor is lipid lowering agent of 3-hydroxy-3-methylglutarylcoenzyme A (HMG-CoA) reductase. It is used to lower the risk of heart attack in patients with diabetic atherosclerosis like James. The active ingredient contained in Lipitor is atorvastatin which works by blocking the enzyme that is used to produce cholesterol in the liver. When that enzyme is blocked, less cholesterol is produced and the amount of cholesterol in the blood decreases, which in turn lowers the risk of a heart attack. Inactive ingredients are hydroxypropyl cellulose, hydroxypropyl cellulose, polyethylene glycol, talc, titanium dioxide, polysorbate 80, calcium carbonate, candelilla wax, croscarmellose sodium, hydroxypropyl methylcellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and simethicone emulsion.Lipitor should be incorporated simultaneously with weight management through a healthy diet and regular exercise, just as James is doing. In addition to this, he should learn how to relax and manage stress.