END-ORGAN DAMAGE OF HYPERTENSION

Question 1

Hypertensive Urgencies and Emergencies

Answer 1

Management:

General recommendations:

Gradual BP reduction is generally recommended:

MAP reduction by ~10% to 20% in first hour, then by

An additional 5% to 15% over the next 23 hours, with

Total 24 hour BP reduction < 25%

Question 2

Hypertensive Urgencies and Emergencies

Answer 2

Exceptions to gradual BP reduction over the first day:

Acute phase of ischemic stroke: BP not lowered unless >185/110 mm Hg in candidates for reperfusion therapy or >220/120 mm Hg for non-candidates.

Acute aortic dissection: SBP should be lowered to target of 100 to 120 mm Hg within 20 minutes and heart rate reduced to <60 beats per minute.

Question 3

Hypertensive Urgencies and Emergencies

Answer 3

Keep patient euvolemic to reduce further activation of the renin–angiotensin–aldosterone system, with caution not to worsen HTN with excess sodium load.

Question 4

Head trauma

Answer 4

Treat if cerebral perfusion pressure (mean arterial pressure minus intracranial pressure [ICP]) is >120 mm Hg and ICP is >20 mm Hg.

Question 5

Acute heart failure

Answer 5

Consider use of intravenous vasodilator such as sodium nitroprusside, nitroglycerin to reduce afterload.

Question 6

Acute heart failure

Answer 6

Avoid hydralazine (can increase cardiac work) or β-blockers, for example, labetalol (can decrease cardiac contractility).

Question 7

Acute coronary syndrome

Answer 7

Consider use of IV nitroglycerin, clevidipine, nicardipine, or esmolol to reduce myocardial oxygen consumption/ischemia.

Question 8

Acute hypertensive nephrosclerosis, renal emergencies

Answer 8

Clinical manifestations: new-onset microscopic hematuria, elevated creatinine

Question 9

Acute hypertensive nephrosclerosis, renal emergencies

Answer 9

Renal histopathology: Fibrinoid necrosis of small arterioles (pink, amorphous fibrinoid materials within vessel wall due to necrosis) and “onion skinning” of small renal arteries.

Question 10

Acute hypertensive nephrosclerosis, renal emergencies

Answer 10

“Onion skinning” is used to describe hyperplastic arteriosclerosis with thickened concentric smooth muscle cell layer with thickened, duplicated basement membrane and narrowed lumen. In malignant HTN, these hyperplastic changes may be accompanied by fibrinoid necrosis of the arterial intima and media.

Question 11

Acute hypertensive nephrosclerosis, renal emergencies

Answer 11

Renal ischemia activates the renin–angiotensin -aldosterone system (RAAS), thus excerbates the underlying HTN.

Question 12

Acute hypertensive nephrosclerosis, renal emergencies

Answer 12

BP lowering may lead to worsening kidney function, particularly CCB due to the potential vasodilating effect on afferent arterioles leading to transmission of systemic HTN into glomeruli.

Question 13

Acute hypertensive nephrosclerosis, renal emergencies

Answer 13

Fenoldopam is associated with a temporary improvement in renal function and may be useful in renal hypertensive emergencies.

Question 14

Ingestion of sympathomimetic agents (e.g., ingestion of tyramine-containing foods in patients on chronic monoamine oxidase inhibitors, cocaine, amphetamine) or severe autonomic dysfunction (e.g., Guillain–Barré, Shy–Drager syndromes), acute spinal cord injury.

Answer 14

Treat with IV phentolamine or nitroprusside.

Use of β-blockers is contraindicated due to unopposed α-adrenergic vasoconstriction. NOTE: nonselective β-blockers such as labetalol and carvedilol still have predominant β-blocking activity with β-to-α blocking ratio of 7:1 or greater.

Question 15

Antihypertensive Medications Used in Hypertensive Emergencies
Nitrates: nitroglycerin, nitroprusside:

Answer 15

NO induces arteriolar and venous vasodilatation by activation of calcium sensitive potassium channels (via cGMP) in cell membranes.

Question 16

Antihypertensive Medications Used in Hypertensive Emergencies
Nitroglycerin

Answer 16

Nitroglycerin:

Low antihypertensive effect

Consider in patients with symptomatic coronary disease or following coronary bypass.

Limitations: methemoglobinemia possible with prolonged use (i.e., >24 hours); no cyanide accumulation

Question 17

Antihypertensive Medications Used in Hypertensive Emergencies
Sodium Nitroprusside

Answer 17

Sodium nitroprusside:

Onset of action: <1 minute; activity loss within 10 minutes of discontinuation

Limitations: cyanide/thiocyanate toxicity: altered mental status, lactic acidosis that may occur within 4 hours

Question 18

Antihypertensive Medications Used in Hypertensive Emergencies
Sodium Nitroprusside

Answer 18

Risks: high dose, prolonged use >24 hours, poor kidney function

For high doses (i.e., 10 mcg/kg/min):

Do not use >10 minutes.

Add sodium thiosulfate as sulfur donor to detoxify cyanide into thiocyanate.

Excessive hypotension may reduce coronary, renal, and cerebral perfusion.

Question 19

NOTE

Answer 19

Sodium nitroprusside and nitroglycerin can potentially increase ICP and reduce cerebral perfusion.

Question 20

Antihypertensive Medications Used in Hypertensive Emergencies
Calcium channel blockers (CCB)

Answer 20

Clevidipine: ultra-short-acting dihydropyridine CCB (half-life 1 minute)

Metabolizes in blood and intravascular tissues by esterases, safe for both kidney and liver failure patients.

Contraindicated in patients with aortic stenosis (potential severe hypotension), dyslipidemia (mixed in lipid-laden emulsion), and known allergies to soy or eggs

Nicardipine: longer onset of action and longer elimination half-life (3 to 6 hours)

Question 21

Antihypertensive Medications Used in Hypertensive Emergencies

Answer 21

Selective dopamine-1 agonist: fenoldopam

Antihypertensive that can maintain or increase renal perfusion

Avoid in patients with glaucoma and sulfite sensitivity

Question 22

Antihypertensive Medications Used in Hypertensive Emergencies

β-blockers

Answer 22

Labetalol:

Combined β- and α-adrenergic blocker: good for patients with acute coronary syndrome. Nonetheless, prior administration of α-blockers (e.g., phentolamine) should be done prior to using labetalol in patients with increased adrenergic states (e.g., PHEO, methamphetamine overdose, tyramine ingestion in patients on monoamine oxidase inhibitor).

Avoid in patients with asthma, COPD, acute heart failure, 2° or 3° heart blocks and bradycardia

Question 23

Antihypertensive Medications Used in Hypertensive Emergencies

β-blockers

Answer 23

Esmolol: cardioselective β-blocker with short half-life and duration of action (9 and 30 minutes respectively)

Question 24

Antihypertensive Medications Used in Hypertensive Emergencies

Answer 24

Hydralazine:

Intravenous form (arteriolar vasodilator, with possible reflex sympathetic stimulation, i.e., tachycardia)

Avoid in patients with coronary artery disease or aortic dissection.

Question 25

Antihypertensive Medications Used in Hypertensive Emergencies

Answer 25

Enalaprilat (intravenous form of enalapril, angiotensin converting enzyme inhibitor): may cause excessive hypotension in hypovolemic patients

Question 26

Suggested Medical Therapy for Specific Clinical Conditions

Answer 26

Acute aortic dissection: intravenous labetalol or esmolol, followed by nicardipine or nitroprusside as needed. Goals: SBP < 100 to 120 mm Hg, heart rate < 60

Question 27

Suggested Medical Therapy for Specific Clinical Conditions

Answer 27

Acute pulmonary edema: nitroglycerin, enalaprilat, or nitroprusside drip. Intravenous furosemide as needed for hypervolemia. Goal BP reduction: 20% to 30%

Question 28

Suggested Medical Therapy for Specific Clinical Conditions

Answer 28

Acute coronary syndrome: nitroglycerin drip, β-blockers such as metoprolol or labetalol bolus therapy. Goal: limit BP reduction to 20% to 30% for SBP > 160 mm Hg

Question 29

Suggested Medical Therapy for Specific Clinical Conditions

Answer 29

Acute sympathetic crisis (cocaine, amphetamines): intravenous benzodiazepine and nitroglycerin or phentolamine drip, or intravenous verapamil bolus. Goal: symptomatic relief.

Question 30

Suggested Medical Therapy for Specific Clinical Conditions

Answer 30

Acute kidney injury (AKI): labetalol bolus or nicardipine or fenoldopam drip. Goal: BP reduction ≤ 20%

Question 31

Suggested Medical Therapy for Specific Clinical Conditions

Answer 31

Severe preeclampsia, eclampsia, HELLP syndrome: labetalol bolus, oral nifedipine or nicardipine. Goal: BP < 160/110 mm Hg, or <150/100 if platelet count < 100,000/mm3.

Question 32

Suggested Medical Therapy for Specific Clinical Conditions

Answer 32

Hypertensive encephalopathy: nicardipine, labetalol, or fenoldopam drip. Goal: decrease MAP by 15% to 20%

Question 33

Suggested Medical Therapy for Specific Clinical Conditions

Answer 33

Subarachnoid hemorrhage: labetalol, nicardipine, or esmolol drip. Goal: SBP < 160 mm Hg or MAP < 130 mm Hg

Question 34

Suggested Medical Therapy for Specific Clinical Conditions

Answer 34

Intracranial hemorrhage: labetalol, nicardipine, or esmolol drip. Goal: MAP 130 mm Hg if increased ICP to maintain cerebral perfusion pressure, otherwise MAP 110 mm Hg

Question 35

Suggested Medical Therapy for Specific Clinical Conditions

Answer 35

Acute ischemic stroke: labetalol or nicardipine drip. Goal: <185/110 mm Hg if fibrinolytic therapy planned

Question 36

Suggested Medical Therapy for Specific Clinical Conditions

Answer 36

Acute postoperative HTN: Manage pain, anxiety; evaluate acute bleed at surgical site. Nicardipine, labetalol, or esmolol drip. Goal: preoperative BP