Hypertension

Mean arterial pressure (MAP) is the average systemic pressure in the arteries. The MAP is tightly regulated to help maintain appropriate perfusion and is primarily determined by the cardiac output (CO) and the systemic vascular resistance (SVR). Cardiac output is determined by the HR and the stroke volume (the volume of blood ejected by the heart each beat). The HR is primarily regulated by the effects of the ANS on the sinoatrial node in the heart, while stroke volume is determined by the preload, afterload, and inotropy (or contractile strength) of each heartbeat. The SVR is regulated by a number of factors, including the ANS, the arterial baroreflex, circulating catecholamines, the RAAS, and several other hormones.

Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. The disorder can usually be managed with lifestyle modification and medications, but occasionally, vascular intervention or surgery are required. Age, sex, smoking, obesity, and diet are contributing factors to hypertension, which can lead to heart attack, stroke, congestive heart failure, and CKD if not managed properly. Many individuals with hypertension are undiagnosed or undertreated.

Although hypertension is defined as a blood pressure of > 130/80 mm Hg, individuals can present with comorbidities of severe asymptomatic or “uncontrolled” hypertension (≥ 180 mm Hg systolic and/or ≥ 120 mm Hg diastolic) that carries with it a significant risk of morbidity and mortality. Despite the prolonged presence of hypertension, there may be no signs or symptoms of end-organ damage (e.g., brain, eyes, heart, kidneys) until function becomes decompensated or severely impaired. Individuals may present with clinical symptoms such as chest pain due to MI or focal neurologic changes associated with a cerebral infarction or intracranial hemorrhage. Diagnosis is made using serial blood pressure measurements and testing for end-organ damage. Management includes lowering the blood pressure and treating specific organ damage.