This lecture on hypertension explains the mechanism of development, risk factors, diagnosis, laboratory investigations, management, follow up and other related aspects of the topic.
Outline of Lecture
Hypertension Defined
“Hypertension (HTN) is defined as sustained abnormal elevation of the arterial blood pressure
Physiology of Blood Pressure
Blood Pressure =
Cardiac Output (CO) X
Peripheral Vascular Resistance
Components of Blood Pressure
Systolic Pressure
Diastolic Pressure
Pulse Pressure
Guidelines
The Seventh Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII) uses the following guidelines to define HTN in adults
Epidemiology
The most common primary diagnosis in the United States, 50 million American affected.
Only 70% are aware they have HTN
Of those aware of their HTN, only 50% are being treated.
Only 25% of all hypertensive patients have their BP under control
HTN is a risk factor for coronary artery disease (CAD), congestive heart failure (CHF), stroke, and renal failure
Cardiovascular risk increases two-fold for each 20mm/Hg rise in systolic pressure or each 10mm/Hg rise in diastolic pressure
Risk factors in all populations include age, obesity, sedentary life-style, family history, smoking, alcohol, high sodium intake, low potassium or magnesium intake, and the use of NSAIDS
Pathophysiology
Primary Hypertension
- Genetics
- Environment
- Neurohormonal mediators
Contributing factors for Primary HTN:
Increased activity of:
- sympathetic nervous system (SNS)
- Renin-angiotensin-aldosterone system (RAA)
Defects in natriuretic hormone function
Inflammation
Obesity
Endothelial dysfunction
Insulin resistance
Primary – 90-95% of cases – also termed “essential” of “idiopathic”
Secondary – about 5% of cases
Renal or renovascular disease
Endocrine disease
Phaeochromocytoma
Cushings syndrome
Conn’s syndrome
Acromegaly and hypothyroidism
Coarctation of the aorta
Iatrogenic
Hormonal / oral contraceptive
NSAIDs
Other forms of HTN
Complicated HTN
Malignant HTN
Hypertensive Crisis
Differential Diagnosis
- Rule out isolated incident of increased blood pressure.
- Rule out secondary hypertension related to:
- Renal disease
- Cushing’s disease
- Pheochromocytoma
- Hyperthyroidism
Clinical Manifestations
Physical exam:
Abdomen
Funduscopic
Vascular
Cardiac
Pulmonary
Neurological
Lab tests:
Urinalysis
Blood Chemistry
ECG
Renal ultrasound
Echocardiogram
Vascular studies
“…properly measured…”
Cuff size
Bilateral
Confirm with manual
No recent caffeine or smoking
Evaluation Of Hypertension
Hypertension is evaluated by a four-step process:
Blood pressure is classified
A diagnostic workup is performed
The patient is then assessed for:
Major cardiovascular disease (CVD) risk factors; and
Identifiable causes of hypertension
Diagnostic workup
Assess risk factors and comorbidities
Find identifiable causes
Assess target organ damage
History /physicial exam
Lab tests
Echocardiogram
Assess CVS risk factors
Obesity
Dyslipidemia
Cigarette smoking
DM
Physical inactivity
Age >55 male,>65 female
Premature family history of CVD
Clinical clues to renal vascular disease
Hypertension under 40 Yrs of age.
Generalised vascular (esp peripheral) disease.
Mild – moderate renal dysfunction.
Sudden onset pulmonary oedema.
ECG
Left ventricular hypertrophy(Voltage criteria)
Limb leads
R wave in lead 1 plus S wave in lead III >25 mm
R wave in lead aVL >11 mm
R wave in lead aVF >20 mm
S wave in lead aVR >14 mm
Precordial leads
R wave in leads V4, V5, or V6 > 26 mm
R wave in leads V5 or 6 plus S wave in lead V1 > 35 mm
Largest R wave plus largest S wave in precordial leads > 45 mm
Non-voltage criteria
ST segment depression and T wave inversion in the left precordial leads
Hypertension: Reason to Treat
Reduced incidence of stroke (35-40%)
Reduced incidence of MI (20-25%)
Reduced incidence of heart failure (50%)
Reduced incidence of renal failure
Therapeutic targets
Management
Primary goal is to reduce cardiovascular and renal morbidity and mortality.
Other keys to management are:
Prevention
Patient education
Life-style modification
Medication
Medications
Diuretics– Thiazides (HCTZ), Loop (Furosemide), Potassium-sparing (Spironolactone)
Beta-Blockers– Atenolol, Nadolol, Propranolol
ACE Inhibitors– Benezapril, Captopril, Cilizapril
Ca+ Channel Blockers– Nifedipine, Verapamil
Alpha blockers- Prazosin, Terazosin
ARBs- Losartan, Valsartan
Vasodilators- Apresoline
Hypertension in elderly
Hypertension is very common, occuring in over 50% of older people, and is a major risk factor for stroke and ischaemic heart disease.
Drug treatment of hypertension in older people saves lives and prevents unnecessary morbidity.
Treating isolated systolic hypertension also saves lives.
Hypertension in the Elderly
Medications to use with caution
Diuretics
Alpha-blockers (i.e. terazosin)
Preferred first line medications
ACE-Inhibitors
β-blocker
Calcium channel blockers
Recognizing Hypertensive Emergency
Signs of end-organ involvement
Severe Headache
Neurologic symptoms
Chest pain
Anuria
When to suspect Secondary Hypertension
HTN refractory to multiple medications
Unexplained hypokalemia
Symptoms consistent with:Pheochromocytoma
Cushing’s syndrome
Hyper/Hypothyroidism
Hyperparathyroidism
Outcome
Follow up
Frequent monitoring is necessary until BP is under control. Once under control office visits can be decreases, with limited laboratory tests.
Lipids should be checked yearly.
ECG every 2-4 years, as indicated by initial ECG
Complications
Complications as a result of HTN include:
Stroke
Dementia
Myocardial Infarction
Congestive Heart Failure
Retinal Vasculopathy
Aortic Dissection
Renal Disease or Failure
Hospitalization
Hospitalization should be considered if:
Very high BP
Severe headache
Chest pain
Neurologic symptoms
Altered mental status
Acutely worsening renal failure
S & S of hypertensive emergency
Hypertensive crisis
Acute or ongoing vital target organ damage, such as damage to the brain, kidney, or heart, in the setting of severe hypertension is considered a hypertensive emergency
It requires a prompt reduction in blood pressure within minutes or hours
Hypertensive urgency
The absence of target organ damage in the presence of severe elevation of blood pressure with diastolic blood pressure frequently greater than 120 mm Hg is considered hypertensive urgency, and it requires reduction in blood pressure within 24-48 hours
A continuum exists between the clinical syndrome of hypertensive urgency and emergency; hence, their distinction may not always be clear and precise
Hypertensive encephalopathy
Accelerated hypertension is associated with group 3 Keith-Wagener-Barker retinopathy, which is characterized by retinal hemorrhages and exudates on funduscopic examination
Malignant hypertension is associated with group 4 Keith-Wagener-Barker retinopathy, which is characterized by the presence of papilledema, heralding the neurologic impairment from an elevated intracranial pressure.
Labetalol: 20 mg IV bolus, then 20-80 mg IV bolus q10min; not to exceed 300 mg; 2 mg/min IV infusion alternatively, titrate to desired BP; not to exceed 300 mg
Nitroglycerin:
Nifedipine
Esomolol
Hypertension in Pregnancy
JNC Guidelines
