Hypertension Penny Mosley MRPharmS
Outline of presentation Introduction to hypertension Physiological control of arterial blood pressure What determines our bp? What determines the heart rate? What determines stroke volume? What determines our peripheral resistance?
Cont., Antihypertensive drugs Drugs that act on the RAAS Diuretics Calcium Channel Blockers α1 Adrenergic antagonists β- adrenergic antagonists NICE guideline CG 127
Introducing Andrew 35 year old male PMH: moderate hypertension SH: lives with fiancée and 2 daughters Smokes 20 cigarettes/day Weighs 95kg
Andrew cont., What are you going to do? What could be his diagnosis? What could be the consequences of this diagnosis?
Hypertension Common in UK1 One of the most important preventable causes of premature morbidity & mortality1 One of the major risk factors CHD2
Hypertension is a risk factor for various conditions3 Primary condition Atherosclerosis of coronary arteries Myocardial infarct Kidney Disease Hypertension Retinal disease Diabetes Secondary consequence Angina Myocardial Infarction Stroke (ischaemic of haemorrhagic) Heart Failure Arrhythmias Hypertension Kidney Disease
Blood pressure ranges (UK) Systolic (mm Hg) Diastolic (mm Hg) Optimal <120 <80 Normal <130 <85 High Normal 130-139 85-89 Hypertension >140 >90
Care pathway for hypertension 4
Physiological control of arterial blood pressure Cardiac Output (CO) Total Peripheral Resistance (TPR) BP = CO x TPR
What determines Blood Pressure? BP = CO x TPR CO = HR x SV BP = HR x SV x TPR
1. What determines Heart Rate?
Sinoatrial Node Action Potential
2. What determines Stroke Volume? Directly influencing ventricular myocytes Indirect influences on SV Changes to the venous side (Venous return, preload & end diastolic volume) Changes to the arterial side (BP and afterload)
2a. Direct influences on cardiac myocytes
SA node vs Ventricular action potentials
2b(i). Indirect influences on SV (venous) Sympathetic stimulation of large veins vasoconstriction Valves ensure blood pumped back towards heart inc venous return inc force of contraction inc stroke volume
2b(ii) Indirect influences on SV (arterial)
3. What determines TPR? Resistance to blood flow is essential for maintenance of normal BP Receptors: α 1 adrenoceptors -contraction of smooth muscle (dominant action) β2 adrenoceptors relaxation
Renin-Aldosterone-Angiotensin System
Problem!!! BP = HR x SV x TPR Role of baroreceptors in controlling BP
Andrew has arrived at A & E BP 220/140 mm Hg Pulse 60 beats/ min (normal) Sodium = 142 mmol/l (135-145) Potassium = 4.2 mmol/l (3.5-5.5) BP = HR x SV x TPR
BP = HR x SV x TPR BP = elevated (220/140 mm Hg) HR = normal (60 beats / min) SV = reduced Hence, TPR must be raised?? Inc (BP) = norm (HR) x red (SV) x inc (TPR)
Quick quiz!!! Measure BP Think about HOW this can be done in your pharmacy who, where etc?? What things do you need to discuss / question with the patient
Antihypertensive Drugs 1. Drugs that act on RAAS ACE inhibitors Angiotensin II antagonists Aldosterone antagonists 2. Diuretics 3. Calcium Channel blockers 4. α-adrenoceptor antagonists 5. β-adrenoceptor antagonists 6. others
1. ACE Inhibitors Reduces vasoncontriction of Angiotensin II, and Na retention / water retention Causes accumulation of bradykinin Potentially serious interaction - triple whammy ACE inhibitors NSAIDS Diuretics
Angiotensin II antagonists Prescribed to patients who can t tolerate the cough with ACEI Similar side effects as ACEI Like ACEI cause a down regulation of vasoconstriction and Aldosterone effects
Aldosterone Antagonists Not routinely used for hypertension Used mainly for HF Potassium sparing diuretics
2. Diuretics Thiazides - stimulate Na/water excretion Act on distal tubule Reduces blood volume and cardiac output (& BP) Thiazides are weaker than loop diuretics Thiazides also have a direct vasodilator effect
3. Calcium Channel Blockers Drugs used in Hypertension act on L-type channel Dihydropyridines (eg Amlodipine) Verapamil Diltiazem Act in 3 sites Conducting system of heart reduces HR Contractile myocytes reduces SV Vascular smooth muscle reduces TPR
4. α-adrenoceptor antagonists Receptors found in smooth muscle vasoconstriction Reduction in BP due to reduction in TPR leads to a compensatory increase in NA (affecting β adrenoceptors in heart) thus reducing effectiveness as drugs usually used in combination
5. β-adrenoceptor antagonists Not now routinely used for hypertension Stimulation of β1 adrenoceptors in heart Increases heart rate Increases force of contraction Increases cardiac output INCREASES BLOOD PRESSURE Problem Baroreceptors/ feedback mechanism
Β adrenoceptors antagonists Work on: Heart : reduce CO Kidney: reduce renin release Brain: reduce sympathetic nervous system activity
6. Other antihypertensive drugs Vasodilators Sodium Nitroprusside Minoxidil Hydralazine Centrally acting sympatholytics Methyldopa Clonidine Moxonidine
Andrew needs rapid reduction of BP BP 220/140 mm Hg Two options: Sodium nitroprusside 1/v Oral labetolol After 24 hours: BP 175/100 mm Hg
Treatment pathway for hypertension 4
Application: tmurs and NMS
Application: tmurs and NMS ressure measurement* se /compliance ifestyle* moking status* ncouragement
Sitting? Standing or Sitting? Which arm? What is high Blood Pressure? How many readings? General tips on measurement Which cuff size? Which device?
Having high blood pressure increases the risk of having a heart attack or stroke. taking xxx medicine, helps to reduce BP and so reduces this risk xxx medicine works best if you use them regularly
Diet / exercise programs Alcohol consumption Salt intake Local initiatives
Ask patient if they smoke add info to form Offer smoking cessation advice / support or referral to specialist service if necessary
NHS choices website www.nhs.uk Other websites British Hypertension Society. www.bhsoc.org Blood pressure UK. www.bloodpressureuk.org Local initiatives Byou. www.b-you.co.uk Healthy lifestyle hub. www.dchs.nhs.uk/your_health_useful_info/
References 1. William H. Updated hypertension guideline: What pharmacists need to know. Clinical Pharmacist. 2011.3.254-256 2. Sherwood J, Ashton M, Ferriman H. Current and future options for the management of hypertension. Pharmaceutical Journal. 2011. 286. 48-9 3. Boarder M, Newby, Navti P. Pharmacology for pharmacy and the health sciences. Oxford. Oxford University Press. 2010 4. National Institute for Health and Clinical Excellence. Clinical guideline 127. Hypertension: clinical management of primary hypertension in adults 5. Shannon R, Davies E. How motivational interviewing can help patients change their lifestyles. Clinical pharmacist. 2010. 2.28 6. Broomhead C. Hypertension targets: improving control and concordance. Prescriber. 2009. 50-53