Hypertension

Blood pressure (BP), the lateral pressure exerted by blood in a unit area of blood vessel wall, is a function of cardiac output and peripheral vascular resistance.1 When the blood volume exceeds the limited volume capacity of the vascular compartment because of volume expansion or increased vascular resistance the patient develops hypertension (HTN). BP is classified as normal (<120/80 mmHg), elevated (120‑129/<80 mmHg), stage 1 HTN (130‑139/80‑89 mmHg), or stage 2 HTN (≥140/90 mmHg).17

HTN is known as the “silent killer” because signs and symptoms, i.e., flushed face, restlessness, headache, dizziness, tinnitus, visual disturbances, dyspnea, and a hammering pulse are not observed until the systolic BP is ≥180 mmHg or the diastolic BP ≥110 mmHg; or until evidence of target organ damage manifests.18 Target organ damage may include renal insufficiency and end-stage renal disease; CAD, left ventricular hypertrophy, and HF; stroke; peripheral vascular disease; and hypertensive retinopathy.18

The treatment of HTN may include (1) diuretics to reduce blood volume, (2) ACE inhibitors or AT II receptor antagonists to modulate the RAAS, (3) β1-adrenoceptor antagonist, α1-adrenoceptor antagonists, and central α2-adrenoceptor agonists to reduce sympathetic tone, and (4) Ca2+ channel blockers and K+ channel activators to reduce vascular tone.4-6,16 It is of note that in many instances two or more agents from different drug classes may be required to reach target BP in a particular patient.

BP <179/109 mmHg is a minor, but not an independent risk factor for a major adverse cardiac event (MACE) in association with dental procedures performed under local dental anesthesia.18 However, high BP is a useful marker for the presence of significant CAD and correlates well with obesity and sedentary lifestyle; significant use of tobacco, coffee, and alcohol; and a number of systemic diseases, e.g., dyslipidemia, diabetes mellitus, thyroid dysfunction, adrenal disease, and renal insufficiency.17,18

Hypertensive urgency is characterized by gradual elevation of BP in patients with chronic, slowly progressive end-organ damage.16 Clinically it may manifest as stroke or myocardial infarction (MI).16 Consider stroke when a patient smiles and one side of the face droops, or when raises both arms and one arm drifts downward; or when speaks and the speech is slurred. Perioperatively, when a conscious patient experiences chest pain and the BP drops from baseline consider the diagnosis of MI.

Hypertensive emergency is a rare life-threatening condition characterized by severe, acute BP elevation associated with acute vascular injury.16 The vascular injury manifests clinically as retinal hemorrhage, papilledema, and altered mental state often accompanied by acute renal insufficiency and acute left ventricular (LV) failure. The treatment of patients with hypertensive emergency mandates rapid reduction of BP in a hospital setting to prevent irreversible end-organ damage.16

Signs and symptoms of hypotension, defined as BP <90/60 mmHg, include dizziness, and fainting (syncope); rapid, shallow breathing; fatigue, lack of concentration, and depression: cold, clammy, and pale skin; and thirst.18 Causes range from impaired homeostatic mechanisms of BP regulation as in old age, dehydration, and antihypertensive therapy.18 Perioperatively, when a conscious patient experiences chest pain and a rise in BP from baseline consider the diagnosis of acute angina pectoris.