High Blood Pressure: The Silent Killer
DOI link for High Blood Pressure: The Silent Killer
High Blood Pressure: The Silent Killer book
The word “hypertension,” when used alone, refers to systemic arterial hypertension. A blood pressure of 120/80 mmHg is considered normal. Hypertension is deŠned as a systolic blood pressure consistently above 140 mmHg and a diastolic blood pressure consistently above 90 mmHg. Blood pressure of 120-140/80-90 mmHg is an intermediate state and deserves attention. Hypertension (HTN) can be classiŠed according to blood pressure (BP) levels as follows:
• Normal: BP ≤ 119/79 mmHg • Pre-HTN: BP 120-139/80-89 mmHg • Exercise HTN: BP ≥ 200/≥90 mmHg associated with exercise in patients
with normal or pre-HTN BP at rest • Isolated systolic hypertension: BP ≥ 140/≤90 mmHg • HTN stage 1: BP 140-159/90-99 mmHg • HTN stage 2: BP ≥ 160/≥100 mmHg • Resistant hypertension: failure to bring BP to appropriate levels with a
three-drug regime that includes hydrochlorothiazides
As the name suggests, pre-HTN is a precursor of HTN. During aerobic exercise, cardiac output increases (the result of increased heart rate, stroke volume, and contractility) as the systemic vascular resistance decreases (the result of vasodilatation); consequently, the BP systolic increases and the BP diastolic remains the same or changes very little. Exercise HTN is the result of impaired vasodilatation due to rigid vascular walls (atherosclerosis) or failure to vasodilate due to re±ex autonomic dysfunction, elevated norepinephrine levels or local paracrine factors within the arterial walls. During isometric exercise, both the systolic and the diastolic BP increase due to re±ex vasoconstriction. Exercise-induced hypertension is more severe in subjects with pre-existing HTN, usually due to higher norepinephrine, rennin, and aldosterone levels in the circulation. In patients with coronary artery disease, exercise can induce myocardial ischemia associated with left ventricular dysfunction, re±ex vasoconstriction, and diastolic hypertension with a diastolic BP > 90 mmHg.