Arterioles and large blood vessels become hardened and constricted leading to an abnormal resistance to blood flow and subsequently an elevated blood pressure. The heart responds by trying to overcome the peripheral resistance. There is therefore an increased cardiac output as the heart tries to pump more blood to the different parts of the body. The continuous resistance puts a greater demand on the heart to increase its pressure thereby leading to an increase in the size of the tissue of the myocardium, a condition known in medical term as myocardial hypertrophy and then cardiomegaly (enlargement of the heart) and coronary insufficiency.
The abnormal resistance to blood flow leads to decrease in blood supply to vital organs such as the heart, brain, kidneys and the lower extremities. This brings about mental confusion, headache, oliguria (a deficiency in the secretion of urine), angina pectoris, dyspnoea, fatigue, etc. The changes in the blood vessels may lead to haemorrhage and intravascular coagulation bringing about occlusion of the blood vessels.
Coronary insufficiency results in myocardial infarction (MI) and subsequently the heart fails. Inability of the heart to pump out blood from the left ventricle into the aorta gradually leads to pulmonary congestion. The kidneys fail as a result of poor blood supply. Arteriosclerotic changes in the tiny vessels make them susceptible to rupture. Rupture occurs as the pressure continues to increase within the vessels. This brings about haemorrhage. Should the rupture occur in the brain there would be stroke (CVA). Epistaxis (nose bleed)occurs as a result of rupture of the tiny vessels of the nose. Bleeding into the retina brings about blurred vision and subsequently blindness. These effects on organs are referred to as “End-Organ damage”.
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