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Pathophysiology of the

cardiovascular system

CORONARY ARTERY DISEASES

• (^) CAD, Myocardial ischemia and Myocardial infarction form a pathophysiologic continuum that impairs the pumping ability of the heart by depriving the heart muscle of Oxygen and nutrients.
• (^) Coronary atherosclerosis- This is an abnormal accumulation of lipid, or fatty substances and fibrous tissue in the vessel wall. These substances block or narrow the vessel thus reducing blood flow to the myocardium.

Clinical manifestations

• (^) Myocardial ischemia- The impediment to

blood flow causes inadequate blood supply

that deprives the muscle cells of oxygen

needed for their survival.

• (^) Angina pectoris refers to chest pain that is

brought about by myocardial ischemia. Angina

pectoris usually is caused by significant

coronary atherosclerosis.

Risk factors

• (^) Non-modifiable Risk Factors
• (^) Family history of coronary heart disease
• (^) Increasing age
• (^) Gender (heart disease occurs three times more often in men than in premenopausal women)
• (^) Race (higher incidence of heart disease in Americans than Africans).

• (^) Modifiable Risk Factors
• (^) High blood cholesterol level
• (^) Cigarette smoking, tobacco use
• (^) Hypertension
• (^) Diabetes mellitus
• (^) Physical inactivity
• (^) Obesity

PREVENTION

• (^) Controlling cholesterol abnormalities- by diet and physical activity, medication therapy may also be prescribed.
• (^) Dietary measures- Soluble fibers enhance the excretion of metabolized cholesterol.
• (^) Physical Activity- Regular, moderate physical activity increases HDL levels and reduces triglyceride levels.
• (^) Inform pts to stop any activity if they develop chest pain, unusual shortness of breath, dizziness or lightheadedness.
• (^) Medications- used in some instances to control cholesterol levels e.g. the lipid-lowering - niacin

Classification

• (^) Typical anginal pain: This is associated with Physical activity, eating a heavy meal, exposure to cold or stress.
• (^) Atypical angina may occur at rest.
• (^) Stable angina- This is transient predictable chest pain lasting 3 – 5 mins. If blood flow is restored no permanent change or damage occurs.
• (^) It is due to chronic coronary obstruction Which results in recurrent predictable chest pain.

• (^) Prinzmetal angina- Chest pain attributable to

transient ischemia of the myocardium that

occurs at rest.

• (^) It occurs due to an abnormal vasospasm of

coronary vessels which results in

unpredictable chest pain

Treatment

• (^) Nitroglycerine
• (^) Beta blockers
• (^) Calcium Channel blockers
• (^) Anticoagulants and antiplatelet agents
• (^) Oxygen administration

Myocardial ischemia

• (^) Myocardial ischemia Occurs due to decreased supply of blood and Oxygen to the myocardium.
• (^) Pathophysiology- Ischemia can occur as a result of formation of atherosclerotic plaques in the coronary circulation.
• (^) As it grows it can occlude the arterial lumen leading to ischemia in the myocardial cells.
• (^) Other causes include coronary spasm, hypotension, hypoxemia and increased demand for oxygen (eg, from a rapid heart rate

Signs and Symptoms of an Acute

Myocardial Infarction

• (^) Cardiovascular- Chest pain or discomfort, palpitations. Heart murmurs. Increased jugular venous distention, Blood pressure may be elevated, tachycardia and dysrhythmias.
• (^) Respiratory- Shortness of breath, dyspnea, tachypnea, and crackles if MI has caused pulmonary congestion. Pulmonary edema may be present.
• (^) Gastrointestinal- Nausea and vomiting.

Signs and symptoms cont..

• (^) Genitourinary- Decreased urinary output may indicate cardiogenic shock.
• (^) Skin- Dependent edema may also be present due to poor contractility.
• (^) Neurologic- Anxiety, restlessness, may indicate increased sympathetic stimulation or a decrease in contractility and cerebral oxygenation.
• (^) Psychological- Fear with feeling of impending doom.

VALVULAR HEART DISORDERS

• (^) Valvular heart disease is characterized by

damage to or a defect in one of the four heart

valves

• (^) The mitral and aortic valves are the most

frequently affected by valvular heart disease.

• (^) In valvular heart disease, the valves become

too narrow and hardened (stenotic) to open

fully, or are incompetent.

• (^) A stenotic valve is constricted and narrowed, impending the forward flow of blood and increasing the workload of the chamber behind the diseased valve.
• (^) In valvular insufficiency or incompetence the valve allows blood flow even when the valve should be closed. It causes blood to leak back into the chamber upstream during systole.
• (^) To compensate for poor pumping action, the heart muscle enlarges and thickens/ hypertrophy, thereby losing elasticity and efficiency.