Systemic Hypertension: It’s Pathology And Clinical Features
Chronic elevation of systolic blood pressure above 160 mm Hg (21.3 KPa) and/or diastolic pressure above 95 mm Hg (12.7 KPa) is defined as arterial hypertension. Elevation of the systolic blood pressure without corresponding rise in diastolic levels should also be taken as abnormal. Bloodpressure values ranging between 140 and 160 mm Hg systolic and 90 and 95 mm Hg diastolic should be considered as borderline hypertension. The terms “mild”, “moderate” and “severe” hypertension are used to denote 90-110, 110-130 and above 130 mm Hg diastolic blood pressure respectively.
The arteries and arterioles show thickening (arteriolosclerosis). The arteriolar changes are well seen in the kidney. Renal vessels show medial hypertrophy and intimal fibrosis (nephrosclerosis). Progressive occlusion of arterial lumen leads to scarring of glomeruli and tubular atrophy. Hypertension accelerates atheroma in the coronary, cerebral and renal arteries and the aorta and its major branches. The small arteries of the brain show microaneurysms (charcot-Bouchard aneurysms). These may rupture resulting in cerebral hemorrhage. Occlusion of the atheromatous vessels leads to infarction in vital organs such as the heart, brain and kidneys. The left ventricle is subjected to pressure overload and it shows concentric hypertrophy followed by dilatation in the later stages. Finally left ventricular failure sets in.
High Blood Pressure
Essential hypertension: The condition is asymptomatic and over 50% of the patients are unaware of the condition. Elevated blood pressure is detected during a routine medical examination in such subjects. A few of them present for the first time in one of the major complications. Many develop symptoms after knowing that they are hypertensives. The symptoms are vague and nonspecific in such patients. These symptoms include fatigue, dizziness, palpitation, headache and anxiety. Though many types of headache have been described, throbbing headache, felt in the suboccipital region on waking after sleep is suggestive of hypertension.
Physical examination may reveal a heaving apex beat and loud aortic second sound in many cases. The pulse may show raised tension (requiring more pressure to obliterate) in some. The blood pressure is persistently elevated. Further physical signs develop as the target organs (heart, brain, kidneys and retinae) are involved.
In secondary hypertension, evidence of the primary disorder may be detectable in many cases. In the others, hypertension may be the only evident abnormality and the diagnosis has to be established by investigation. Coarctation of the aorta has to be diagnosed by the detection of weak or delayed femoral pulse and the presence of hypertension in the upper limbs with lower pressure in the lower limbs.
Renal artery bruit may be auscultated over the abdomen lateral to the umbilicus or over the renal angles. Palpating the kidneys suggests polycystic disease, hydronephrosis or tumour.
© 2014 Funom Theophilus Makama