Blood Pressure Conditions Flashcards
Hypertension stages and lifestyle changes
- The purpose of treating hypertension is to the risk of stroke, coronary events, heart failure and renal impairment.
- Stage 1 hypertension: is 140/90 mmHg or higher. Treat patients under 80 years old only if target-organ damage (heart, kidney, diabetes) or if 10-year cardiovascular risk is more than 20%.
- Stage 2 hypertension: is 160/100 mmHg or higher. ALL patients should be treated.
- Severe hypertension: systolic over 180 mmHg or diastolic over 110 mmHg.
- Lifestyle changes: smoking cessation, weight reduction, reducing alcohol + caffeine intake, reducing salt + sat. fat.
HTN treatment
- More than one drug is usually needed to control hypertension, drugs should be added step-wise and usually with a gap of 4 weeks between each initiation to determine the response.
< 55 years old:
Step 1) ACEI/ ARB
- if contraindicated, consider Beta-blocker
Step 2) ACEI/ARB + Calcium channel blocker
- if not tolerated or risk of HF…… consider Thiazide related diuretic (e.g. Chlortalidone or Indapamide)
NOTE: if B-blocker given in Step 1, then a Calcium channel blocker would be given in preference to a Thiazide related diuretic
Step 3) ACEI/ARB + Calcium channel blocker + Thiazide related diuretic
Step 4) Step 3 + low dose spironolactone or increase dose of thiazide diuretic if the plasma conc. is > 4.5mmol/L
- if thiazide diuretic therapy is contraindicated then alpha or beta blocker can be given instead
> 55 years old or Afro-Caribbean:
Step 1) Calcium channel blocker
- if not tolerated or high risk of HF…. give Thiazide related diuretic (e.g. Indapamide or chlortalidone)
Step 2) Calcium channel blocker or Thiazide related diuretic + ACEI/ARB
NOTE: ARB most preferred in afro-carribeans
Step 3 & 4) Same as <55
- Aspirin and statins are often added if risk of cardiovascular disease is high.
The Antihypertensive of choice in pregnancy is
METHYLDOPA, Labetalol is also widely used.
- ACE inhibitors and ARB’s can lower the baby’s blood pressure and inhibit growth.
Systolic pressure raised
If just the systolic pressure is raised (>160mmHg), then treat as regular hypertension; raised systolic pressure still poses an increased risk of cardiovascular disease.
Renal disease and HTN
may need treatment with an ACE inhibitor (with caution); thiazides may not work so high dose loop diuretics may be required.
Severe Hypertension management
(>180/110 mmHg)
Severe hypertension without acute target-organ damage is defined as a hypertensive urgency
Blood pressure should be reduced gradually over 24-48 hours with oral antihypertensive therapy such as Labetalol or the CCB’s Amlodipine or Felodipine.
BP targets
- <140/90 mmHg for patients <80.
- <130/80 mmHg for those with cardiovascular disease, diabetes or kidney/eye/cerebrovascular disease
- <150/90 for patients >80.
Antihypertensive Drugs: Vasodilators
- Vasodilators include hydralazine, minoxidil and Sildenafil and they have a potent hypotensive effect, especially when used in COMBINATION with a beta-blocker and a thiazide. Vasodilation causes increased cardiac output + tachycardia and the patients develop fluid retention. Hence, a beta-blocker and a diuretic (usually Furosemide in high dose) are mandatory.
- Hydralazine is used for resistant hypertension. It is RARELY used + usually never used on its own. When used alone it causes tachycardia + fluid retention.
- Minoxidil is used for severe hypertension, resistant to other drugs.
- Sildenafil is licensed for use in pulmonary arterial hypertension under specialist supervision.
Antihypertensive Drugs: Centrally acting
- Methyldopa is a centrally acting antihypertensive (causes CNS to reduce sympathetic tone) and is particularly useful for treating hypertension in pregnancy. Can cause drowsiness.
- Clonidine hydrochloride has a disadvantage that sudden withdrawal of treatment may cause severe rebound hypertension
- Moxonidine is a centrally acting drug licensed for mild-moderate hypertension. It can be used when other drugs have failed to control blood pressure.
- Blood counts and liver function should be monitored
Antihypertensive Drugs: Alpha-adrenoceptor blocking drugs
- These drugs can be used with other antihypertensive’s in the treatment of resistant hypertension. They block alpha receptors and have vasodilator properties.
- However, they may reduce blood pressure rapidly after the first dose and should be introduced with caution.
- Examples include Doxazosin, Prazosin + Terazosin
Antihypertensive Drugs: ACE inhibitors
- ACE inhibitors inhibit the conversion of Angiotensin I to Angiotensin II. They have many uses and are well tolerated.
- In heart failure (see above) they can reduce blood pressure rapidly after the first dose if patients are taking a high-dose loop diuretic, so monitoring is required.
- It is the most appropriate drug initial drug for hypertension in younger Caucasian patients. They are particularly indicated for hypertension in patients with Type 1 diabetes with nephropathy.
- They may reduced BP very rapidly in some patients, particularly those receiving diuretic therapy. Hence there must be close supervision, and, in some cases, the diuretic dose may need to be reduced or discontinued atleast 24 hours beforehand.
- ACE inhibitors are used in the early and long-term management of patients who have had a myocardial infarction. They also have a role in preventing cardiovascular events.
- Initiate ACE inhibitor under specialist supervision if patient has severe or unstable heart failure, is taking multiple or high-dose diuretics (e.g. >80mg furosemide daily), hypovolemia, hyponatremia, hypotension (systolic <90mmHg), concomitant ARB or aliskiren, is on high-dose vasodilators, or has renovascular disease
- Using an ACE inhibitor with a potassium-sparing diuretic e.g. spironolactone or amiloride) will increase the risk of hyperkalaemia
- Renal function and electrolytes should be checked before and during treatment with ACE inhibitors. Hyperkalaemia and other side effects are more common in those with impaired renal function and the dose may need to be reduced.
- Using an ACE inhibitor with an NSAID increases the risk of renal damage. Hence, if ACE inhibitors are used, the renal function should be monitored regularly.
- The most notable side effect of ACEI is a persistent, dry cough. They may also cause diarrhoea or constipation, hyperkalaemia, hypoglycaemia, hepatic impairment + blood disorders.
- Products incorporating an ACEI with a thiazide diuretic or a calcium-channel blocker are available. However, these should be reserved for patients whose blood pressure has not responded to a single drug, and who have been stabilised on individual components of the combination in the same proportions.
Antihypertensive Drugs: ARB
Examples include candesartan, losartan, irbesartan + olmesartan and they are very similar to ACEI, but they do not inhibit the breakdown of bradykinin… hence less likely to cause persistent dry cough.
They are therefore useful alternatives for patients who have to discontinue an ACEI due to the persistent cough. However, Candesartan and Valsartan may be used with an ACEI under specialist supervision.
Antihypertensive Drugs: B-blockers
Beta-blockers with a short duration of action have to be given 2-3 times daily. Many of these are however are available in modified-release formulations so they can be administered once daily. Atenolol and Bisoprolol have a longer duration of action and only need to be given once daily.
When there is no alternative, it may be necessary for patients with well-controlled asthma or COPD to receive treatment with a beta-blocker for a co-existing condition (e.g. heart failure or after an MI). In this case, a low dose cardio-selective beta-blocker should be used. Examples: Atenolol + Bisoprolol which are cardioselective NOT cardiospecific. They have less effect on airways-resistance but are not free of this s.e.
Beta-blockers also interfere with metabolic and autonomic responses to hypoglycaemia, thereby masking symptoms such as tachycardia. However, they are not contraindicated in diabetes, although cardioselective drugs may be preferred.
- The drugs should be avoided in patients with frequent episodes of hypoglycaemia. Furthermore, when combined with a thiazide-diuretic, they should be avoided for routine treatment of uncomplicated hypertension in patients with diabetes or at a high risk of developing diabetes.
These drugs are effective for reducing blood pressure but other antihypertensives are more effective for reducing the incidence of stroke, myocardial infarction, and cardiovascular mortality.
Beta blockers can be used to control pulse rate in patients with pheochromocytoma (tumour of adrenal glands). However, they should never be used alone as beta-blockade without concurrent alpha-blockade may lead to a hypertensive crisis.
Beta-blockers act as anti-arrhythmic drugs by attenuating the effects of the sympathetic system on automaticity and conductivity of the heart. They can be used with digoxin to control ventricular response in atrial fibrillation.
They are also useful in managing supraventricular tachycardias and are used to control those following an MI.
Beta-blockers are used in preparation for THYROIDECTOMY (removal of thyroid gland). The Thyroid gland is rendered less vascular which makes surgery easier .
Administration of Propranolol can reverse symptoms of thyrotoxicosis (hyperthyroidism) within 4 days!
Antihypertensive Drugs: CCB
CCB’s have various sites of action and therefore produce a variety of therapeutic effects.
- Verapamil and diltiazem should usually be avoided in HF because they may further depress cardiac function and cause deterioration.
Verapamil is used for the treatment of angina, hypertension and arrhythmias. It is a highly negative-inotropic CCB and it reduces cardiac output, slows heart rate and may impair atrioventricular conduction. It may precipitate HF and cause hypotension at high doses and should not be used with beta-blockers. Constipation is the most common side effect.
Nifedipine relaxes vascular smooth muscle and dilates coronary and peripheral arteries. It has more effect on vessels and LESS on the myocardium than Verapamil + has no anti-arrhythmic activity. It rarely causes HF because any negative inotropic effect is offset by a reduction in left ventricular work.
Nicardipine, Amlodipine and Felodipine have similar effects to Nifedipine. But they have a longer duration of action and can be given ONCE daily. They are used to treat hypertension or angina.
- Common Side effects associated with vasodilation include flushing, headache (these two become less obstructive after a few days) + ankle swelling (which may respond partially to diuretics).
- I.V. Nicardipine is licensed for the treatment of acute life-threatening hypertension.
- Diltiazem is effective in most forms of angina, the longer acting form is also used for hypertension.
- It may be used in patients in whom beta-blockers are contraindicated or ineffective. It has a less negative inotropic effect than Verapamil and myocardial depression occurs rarely. Nevertheless, due to the risk of bradycardia it should be used in caution with beta-blockers.
CCB’s do not reduce the risk of MI in unstable angina. Diltiazem or Verapamil should be reserved for patients resistant to treatment with beta-blockers.
CCB poisoning signs: nausea, vomiting, dizziness, agitation, confusion, and coma in severe poisoning. Metabolic acidosis and hyperglycaemia may occur. In overdose, dihydropyridine CCB’s cause severe hypotension secondary to profound peripheral vasodilatation
Hypotension and shock
- Shock is a medical emergency and causes include myocardial insufficiency, haemorrhage and sepsis.
- Cardiac output can be improved by using sympathomimetic inotropes such as adrenaline, dobutamine or dopamine.
- In septic shock, when fluid replacement and inotropic support fail to maintain blood pressure, the vasoconstrictor noradrenaline can be used.
- Treatment: Vasoconstrictor sympathomimetics raise blood pressure by acting on alpha-adrenergic receptors to constrict peripheral vessels. They are used as an emergency method of elevating blood pressure when other measures have failed.
Although they raise blood pressure, they may also reduce perfusion of vital organs e.g. the kidney.
