Hypertension Revision Notes

Hypertension in Canada

In 2015, close to 7% of Canadians over 12 years old had diabetes. Obese (13.6%) and overweight (6.6%) Canadians are more like to have diabetes than those with a normal weight (3.2%). 


Management of Hypertension in Adults

Measuring Blood Pressure 

In the office use automated office BP monitoring (AOBP), and if high BP found, confirm with out of office blood pressure measurement - to rule out white coat hypertension and identify masked hypertension. The diagnosis is based on finding elevated BP during the out-of-office BP measurement.  The preferred method for out-of-office BP measurement is ambulatory measurements. With AOBP the machine calculates the mean BP. With manual measuring, take 3 BP measurements, discount the first, and average the remaining two.  

Cases

(1) Patient has high-normal blood pressure  --> annual follow-up recommended
   
(2) Patient has high blood pressure: BP ≥140/90 using manual measurement, BP ≥135/85 using automated measurement, and BP ≥130/80 if patient has diabetes). The difference is because the automated devices are more accurate and somewhat mitigate the white-coat hypertension effect, and for patients with diabetes they are at higher risk, therefore the threshold is lower.  -->

• Ask them to take out-of-office blood pressure measurements to rule out white-coat hypertension. If they return with out-of-office measurements that are high, then patient they will be diagnosed with hypertension.  
• Perform a history and physical exam. 
• Order tests for organ damage (EKG, urinalysis, electrolytes, creatinine, fasting glucose/ HbA1c, lipid profile - total cholesterol, LDL, HDL, TG). Also, a urinary albumin to creatinine ratio (ACR) if diabetic; normal urine micro-ACR < 2.0 mg/Mmol. 
• Do a cardiovascular risk assessment: use a multi-factorial risk assessment model like the Framingham Risk Score (FRS). 
• This should all be done within the next 2 visits, which are to occur within a month.

(2) Patient has very high blood pressure (BP ≥ 180/110) --> diagnose with hypertension

History and physical exam, tests for organ damage, CVS risk assessment


Managing Hypertension

Target blood pressure goals for patients receiving treatment

• High risk patients --> SBP </=120
• cardiovascular disease
• chronic kidney disease
• estimated 10-year global cardiovascular risk ≥15% using Framingham risk score
• Age ≥ 75 years
• Diabetic patients --> BP <130/80
• All other patients --> BP < 135/85 (AOBP), BP <140/90 (manual)

Note about high-risk patients: they require regular use of medications to reach this goal, therefore, exclude those who are unwilling or unable to adhere to multiple medications. Also since this BP goal is lower than usual, exclude those with standing SBP <110, and if unable to measure SBP accurately. Also exclude if there is a secondary cause of hypertension. The benefits of this lower BP goal has limited/ no evidence in those with Heart failure (EF <35%) or recent MI (within last 3 months), those with an indication for, but not currently receiving, a beta-blocker, and in the institutionalized elderly. 

Health Behaviour Management

• Exercise -- 30-60 minutes of moderate intensity exercise for 4-7 days per week in addition to the routine activities of daily living
• Weight -- goal is a body mass index of 18.5-24.9, and waist circumference < 102 cm for men and < 88 cm for women. If overweight, lose weight.
• Diet -- DASH diet
• Alcohol -- have < 2 drinks per day,  < 14 drinks per week for men,  < 9 standard drinks per week for women
• Sodium -- have < 2g of sodium per day (5g of salt)
• Potassium -- consume more in the diet if not at risk for hyperkalemia
• Smoking -- cessation does not have a known effect on blood pressure, but it will hep reduce risk of cardiovascular disease.

Medications

Cases

(1) Patient has hypertension but is otherwise healthy

A single pill combination (SPC) is the preferred initial choice for patients with hypertension. SPC combining an ACEI/ARB with CCB/Diuretic is preferred.

• ACEI/ARB --> Contraindicated in pregnancy, use caution if woman of child-bearing age. Also not recommended in people of African descent.
• Beta-blockers --> not first line for those > 60 years old. 

Monotherapy with a thiazide-like diuretic is also another option. Longer-acting (thiazide-like) medications e.g. chlorthalidone, indapamide are now the preferred initial drug, rather than the shorter-acting (thiazides) like hydrochlorothiazide. This is because the thiazide-like drugs have the additional benefit of reducing coronary events and all-cause mortality.


(2) Patient has isolated systolic hypertension but is otherwise healthy

Monotherapy with thiazide-like diuretic. Other options: Thiazides, ARBs, or long-acting dihydropyridine CCBs.

(3) Patient has diabetes and hypertension.

Monotherapy with ACEI/ARB if high-risk (organ damage, high CVS risk, etc). If otherwise healthy, then options of thiazide/ thiazide-like, or long-acting dihydropyridine CCBs.

(4) Patient has heart failure and hypertension.

ACEI/ARB plus beta-blocker (BB). If BB is contraindicated, then a long-acting dihydropyridine CCBs. **Note do not give non-dihydropyridine CCBs! in patients with heart failure**

(5) Patient has coronary artery disease and hypertension

Primary therapy is ACEI/ARB or BB/CCB if stable angina. Secondary therapy is ACEI/ARB plus BB/dihydropyridine CCB.

(6) Patient had a recent MI and has hypertension

BB plus ACEI/ARB

(7) Patient has chronic kidney disease and hypertension.

ACEI/ ARB

(8) Patient has hypertension due to atherosclerotic renal artery stenosis but otherwise healthy.

Same as for (1) SPC or thiazide-like diuretic is first choice

(9) Patient has hypertension due to complicated atherosclerotic renal artery stenosis (bilateral renal artery stenosis or unilateral stenosis but patient has only one kidney)

Consider renal artery angioplasty and stenting

(9) Patient has hypertension due to renal fibromuscular dysplasia

consider revascularization


Secondary Causes of Hypertension

Fibromuscular dysplasia (FMD)

• Rare, ~4% of adults
• More common in young women. Male to Female ratio is 1:9
• segmental, non-atherosclerotic narrowing of small and medium sized arteries
• more than 1/2 have renal artery narrowing, cranial vessels often affected too (headaches, dizziness, cervical bruits, tinnitus, neck pain)
• Initial diagnostic test: CT/MR angiography
• Confirm with the gold standard test: catheter based angiography

Hypertensive Emergencies

When blood pressure rises so much that the body is not able to maintain proper blood flow to vital organs such as the brain (cerebral blood flow vs. mean arterial pressure) then there is the risk of damage to these organs. A hypertensive emergency is defined as the presence of evidence of organ dysfunction due to increased blood pressure - the exact BP value is not as important. Therefore, when giving IV blood pressure medications look for improvement in symptoms/ signs of organ dysfunction, not just the BP numbers.  Examples of specific organ dysfunction and suggested blood pressure lowering medications are listed below:

• Hypertensive encephalopathy: increased intracranial pressure (ICP), vasodilation, cerebral edema --> headache, visual changes, nausea/ vomiting, non-focal neurologic deficits/ confusion, seizures, coma --> non-contrast head CT to rule out hemorrhage. Drug of choice: IV Labetalol, manage in ICU, goal is to reduce MAP by 20% to 25% over 2 to 8 hours
• Acute pulmonary edema: pink sputum, dyspnea, heavy chest pain --> Nitroglycerin (IV or sublingual sprays) to reduce preload (venodilation) and ACEI (IV enalaprilat or sublingual captopril) to reduce afterload. The goal is to reduce MAP by 20% to 25%.
• Aortic dissection: tearing chest pain radiating to the back, blood pressure difference between arms, sudden death --> urgent imaging (CT/MRI/TEE) --> First, lower heart rate with IV beta-blockers, then lower the blood pressure with IV Nitroprusside. Note: nitroprusside broken down to cyanide, so harder for patients with renal failure to clear it. Lower the HR before the BP to avoid reflex tachycardia which can propagate the dissection. IV Labetalol, is a good beta-blocker to give because it lowers the HR and BP because it blocks both beta and alpha receptors. Goal is to reduce HR <60 bpm within 20 minutes and SBP to 100-120 mmHg if no signs of hypoperfusion.
• Subarachnoid hemorrhage: new sudden onset severe headache --> non-contrast head CT --> IV Labetalol /Esmolol. Days later, you may need Nimodipine PO to reduce vasospasm but not specifically for lowering BP. Goal is to reduce SBP 120-160 mmHg or MAP <130 mm Hg
• Intracranial hemorrhage: non-contrast head CT --> IV Labetalol /Esmolol. If SBP 150-220 mmHg, target SBP 140 mmHg. Monitor BP every 5 minutes and aim for target within 1 h.
• Pre-eclampsia and Eclampsia: IV Labetalol/ Hydralazine (direct arterial vasodilator, raises HR). 
• Acute renal insufficiency: newly elevated creatinine (check recent creatinine level), proteinuria --> IV Labetalol. Avoid nitroprusside and ACEIs. Admit patient for further workup. 
• Left ventricular failure: IV Nitroglycerin intravenous, IV ACEI (Enalaprilat), IV Nitroprusside. 
• Myocardial ischemia, infarcts: IV Nitroglycerin, IV Labetalol / Esmolol/ Metoprolol
• Ischemic stroke: acute onset neurologic deficit --> non-contrast head CT --> IV labetalol
• Acute Sympathetic Crisis (Pheochromocytoma, Amphetamines, Cocaine): 24h urine for catecholamines, metanephrines, urine drug screen, history --> IV Benzodiazepine / Nitroglycerine/ Verapamil/ Phentolamine. Avoid Labetalol and beta-blockers are contraindicated in cocaine toxicity because unopposed beta-blockade can cause an alpha-storm. Watch respirations 

Tips: IV Labetalol is a good option for hypertensive emergencies with the exception of patients with congestive heart failure and in acute sympathetic crisis. Lower BP 20-25% over the first few hours with the exception of aortic dissection in which you want to lower the BP quickly.


References: 
Stats Canada Health Facts Diabetes 2015
http://www.statcan.gc.ca/pub/82-625-x/2017001/article/14763-eng.htm
2017 Canadian HTN guidelines
http://guidelines.hypertension.ca/  
http://www.onlinecjc.ca/article/S0828-282X(17)30110-1/pdf
Framingham and other CVS risk calculators
https://www.ccs.ca/en/resources/calculators-forms
Cardiovascular Pharmacotherapy Handbook (University of Toronto)
http://pie.med.utoronto.ca/CVmanual/CVManual_content/CardiacDiseasesAndTherapies.html
CFPC Journal - Hypertensive Emergency Management
http://www.cfp.ca/content/57/10/1137
Emergency Medicine Cardiac Research and Education Group
http://www.emcreg.org/pdf/monographs/2008/cline2007.pdf