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Cardiovascular System

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  1. CLARE SHALDERS/GOTAFE/2008 Cardiovascular System HLT 43407 ClareShalders/2009

  2. Heart failure Underlying heart failure impairment of the pumping ability of the heart Nature of impairment depends on the side of the heart involved CLARE SHALDERS/GOTAFE/2008

  3. Right side of heart fails, blood accumulates in the venous circulation, causing organ congestion and peripheral tissue oedema Left side fails blood accumulates in the pulmonary circulation, resulting in pulmonary congestion, and fluid in the lungs. CLARE SHALDERS/GOTAFE/2008

  4. The impairment of ventricular ability results in significant volume of blood remaining in the chamber after contraction. This stress is called preload CLARE SHALDERS/GOTAFE/2008

  5. Left side of the heart is called CCF Eventually impairment of one side of the heart leads to involvement of both sides

  6. To compensate for decreased cardiac output, compensatory mechanisms take place. Long term these mechanisms amplify the problem rather than overcome it. The increase in workload called afterload, means that the myocardium requires more oxygen CLARE SHALDERS/GOTAFE/2008

  7. CLARE SHALDERS/GOTAFE/2008 Terms Inotropes: affect the force of the heart muscle contraction Positive inotropes increase force of myocardial contraction eg. Adrenaline, digoxin, dobutamine Negative inotropes decrease the force of myocardial contraction e.g Beta blockers eg. propanolol

  8. CLARE SHALDERS/GOTAFE/2008 Terms Chronotropic drugs affect heart rate Positive chronotropic speed up by increasing impulse formation in SA node, eg. Adrenaline Negative chronotropic has opposite effect, slows rate down, e.g. digoxin Dromotropic drugs affect conducting system velocity (speed) Positive action e.g. adrenaline Negative: digoxin, calcium channel blockers eg. verapamil

  9. CLARE SHALDERS/GOTAFE/2008 Adrenergic Receptors Sympathomimetic drugs (adrenergic agonists) directly stimulate alpha and beta adrenoceptors Alpha receptors 1&2 Vasoconstrict arterioles of the skin Pupil dilation Relaxation of the gut

  10. CLARE SHALDERS/GOTAFE/2008 Adrenoceptor antagonists Beta adrenoceptor antagonists drugs Beta blockers Beta 1 selective blockers cardioselective Beta 1 & 2 non selective adrenoceptor antagonists Cardiac muscle contains mainly beta 1 Smooth muscle contains mainly beta 2

  11. CLARE SHALDERS/GOTAFE/2008 Beta Adrenoceptor Blocking Agents Beta Blockers – inhibit the effect, of catecholmines at beta adrenergic receptor sites. Some agents have equal affinity for beta 1 and beta 2 receptors. ( non cardioselective propanolol/ cardioselective atenolol, metoprolol) may reduce the incidence of bronchospam

  12. CLARE SHALDERS/GOTAFE/2008 Beta Blockers Depress myocardial contractility and reduce the heart rate. In addition reduces oxygen demand, B Blockers may also increase the perfusion of the ischaemic area, because the decrease in heart rate increases the duration of diastole and hence the time available for coronary blood flow Two types alpha and beta Beta blockers block the beta receptor Some also block the alpha receptor

  13. CLARE SHALDERS/GOTAFE/2008 Action Block the adrenoceptors, thereby reducing some of the responses of the body to adrenaline, noradrenaline and isoprenaline. Some are more specific for receptors dominant in the heart (beta 1) others block receptors in the lungs (beta 2) as well as the beta 1 receptors

  14. CLARE SHALDERS/GOTAFE/2008 Beta Blockers Action Reduces cardiac rate and force of contraction Reduced cardiac output and cardiac demand Reduced BP Reduced response to stress Inhibition of renin release from kidney

  15. CLARE SHALDERS/GOTAFE/2008 Beta Blockers Use Hypertension Angina pectoris (temporary interference with blood flow that reduces oxygen and nutrient supply to heart muscle) Cardiac arrythmias Myocardial infarction Tacycardia

  16. CLARE SHALDERS/GOTAFE/2008 Adverse effects: Bronchospasm (uncommon but serious) Bradycardia, postural hypotension Nausea, vomiting, diarrhoea, constipation, indigestion and dry mouth Cold extremities Fatigue, dizziness, headache, malaise Depression ,mood changes Effect on lipid and glucose metabolism Sleep disturbances

  17. CLARE SHALDERS/GOTAFE/2008 Beta Blockers Beta blockers should not be stopped suddenly Most effective when used with an ACE Client should have sitting systolic BP above 85mmHg, and heart rate above 55bpm before commencing beta blockers

  18. CLARE SHALDERS/GOTAFE/2008 Cardioselective Inhibit 1 receptors in cardiac smooth muscle Examples include Metoprolol (Betaloc, Lopresor) Atenolol (Tenormin, Noten) Safe for use in people with respiratory conditions or prone to bronchospasm

  19. CLARE SHALDERS/GOTAFE/2008 Non – Cardioselective > Inhibit B1 receptors in cardiac smooth muscle and B2 receptors in bronchial and vascular muscle > Examples include Pindolol (Visken) Labetalol (Trandate)

  20. CLARE SHALDERS/GOTAFE/2008 Implications for nursing Monitor blood pressure for effect of medication Monitor patient for any breathing difficulties or bradycardia Side effects are weakness and drowsiness Can cause wheezing and should be used with caution in patients with asthma, bronchitis or emphysema

  21. CLARE SHALDERS/GOTAFE/2008 Angiotensin converting enzyme (ACE) inhibitors Act as antagonist of the renin-angiotensin system Interfere with the conversion of angiotensin 1 to angiotensin 2 by inhibiting the angiotensin converting enzyme

  22. This results in the dilation of peripheral blood vessels and a reduction in blood pressure excretion of sodium and water is enhanced and potassium is retained. Inhibition of aldosterone release, reducing sodium and water reabsorption Eg. captopril (Capoten) and enalapril ) (Renitec)

  23. Cardiac after load is reduced and aldosterone mediated sodium and fluid retention is diminished. Major advantage of this group is they produce there effects without compromising cardiac function by reducing cardiac output or altering heart rate. Eg. captopril (Capoten) and enalapril ) (Renitec) CLARE SHALDERS/GOTAFE/2008

  24. CLARE SHALDERS/GOTAFE/2008 Are indicated for: Hypertension, heart failure, diabetic nephropathy, left ventricular dysfunction and after myocardial infarction Preserving kidney function in diabetes Most of these drugs maintain antihypertensive effect for up to 24 hours allowing once daily dosing

  25. CLARE SHALDERS/GOTAFE/2008 Adverse reactions Persistent dry cough Headache Diarrhoea Loss of taste Weakness Nausea Dizziness Hypotension Rash Fever Joint pain

  26. CLARE SHALDERS/GOTAFE/2008 The suffix pril useful guide to identifying individual generics One of major advantages are they produce their affects without compromising cardiac function Caution in patients with renal impairement Caution with use of NSAIDS during ACE therapy as can reduce the effectiveness of the ACE.

  27. First dose of ACE may cause severe hypotension, commenced with low dose and titrated. Can be given in combination with diuretics. Potassium sparing diuretics not recommended due to risk of hyperkalaemia. CLARE SHALDERS/GOTAFE/2008

  28. CLARE SHALDERS/GOTAFE/2008 Angiotensin Receptor Antagonists Agents such as candersartan, irbesartan, losartan block the receptors for angiotensin 11 Inhibit vasoconstriction and the increase in aldosterone release( similar to ACE)

  29. Losartan Duration of action 24 hours Metabolised in liver and excretion in bile (60%) and urine(35%) Adverse reactions – headache tiredness dizziness, hypotension and GIT disturbances Cause less cough then ACE,

  30. CLARE SHALDERS/GOTAFE/2008 Action They prevent angiotensin from binding to it’s receptor in the walls of the blood vessels. Resulting in lower blood pressure Do not cause a cough as a side effect Can help kidney function Anti inflammatory effect on the walls of the blood vessels Eg. Atacand

  31. CLARE SHALDERS/GOTAFE/2008 Angina Medications Control the symptoms of angina caused by blocked or narrowed coronary arteries. They can not fix the blockage

  32. Angina Medications Only bypass or angioplasty can resolve the blockages Angina patients commonly treated with asprin, helps prevent narrowing in artery from progressing to a full blown heart attack

  33. CLARE SHALDERS/GOTAFE/2008 Angina Medications Medications to prevent angina from occurring include Long acting nitrates Beta Blockers Calcium Channel Blockers Lowering the serum cholesterol levels helps the arteries of the heart dilate

  34. CLARE SHALDERS/GOTAFE/2008 Coronary Vasodilators Drugs that dilate the coronary blood vessels are primarily used on the treatment of angina pectoris A condition characterised by either an imbalance in the supply and demand of oxygen by cardiac tissue or by obstruction or narrowing of the coronary arteries caused by atherosclerosis Nitrates are very useful in the treatment of angina

  35. CLARE SHALDERS/GOTAFE/2008 NITRATES Their action results in the relief of ischaemia in coronary blood vessels They improve the delivery of oxygen to ischaemic tissue by increasing coronary blood flow They reduce oxygen consumption of the heart by dilating peripheral blood vessels. GTN (Glyceryl trinitrate) is shown to be effective in 90% of people with angina within 5 minutes

  36. CLARE SHALDERS/GOTAFE/2008 If the body exposed to nitrates continuously the body becomes tolerant to them Essential to have a nitrate-free interval every day Most commonly done at night, when at rest Sublingual tablets are used for acute attacks. Should be placed under the tongue and dissolve. Repeated at five minute intervals total of three. If chest pain not relieved in 15 minutes should call ambulance. Transient headache and flushing may occur post dose.

  37. CLARE SHALDERS/GOTAFE/2008 NITRATES GTN comes in many forms Tablets for sublingual administration Patch for transdermal application Ointment for transdermal application Liquid for intravenous infusion Isosorbide Trinitrate has a longer duration of action and is administered as an oral tablet Used in the prevention of angina

  38. CLARE SHALDERS/GOTAFE/2008 NITRATES - GTN Volatile substance Quickly rendered inactive by light, heat, air and moisture Sublingual tablet is the most predictable form Tolerance can develop so use of the smallest effective dose is recommended

  39. CLARE SHALDERS/GOTAFE/2008 GTN – Nursing implications Common side effects include Headache Hypotension Syncope Nausea Ensure regular haemodynamic monitoring Start with the smallest dose Use oxygen therapy Educate patient about how to take medication

  40. CLARE SHALDERS/GOTAFE/2008 GTN – Nursing implications With sublingual GTN Ask patient to take a sip of H2O prior to tablet Do not chew or swallow Encourage patient to rest/do not move until episode of angina has resolved Educate patient about how to store GTN products properly Look up Glyceryl Trinitrate

  41. CLARE SHALDERS/GOTAFE/2008 CARDIAC GLYCOSIDES Digitalis demonstrates a herbal recipe, used by common people for dropsy Term digitalis glycoside refers to cardiac glycosides derived from digitalis species and includes digoxin

  42. A very effective treatment for congestive heart failure which is often the result of the sustained presence of one or more underlying cardiovascular diseases Symptoms of heart failure include weight gain, oedema, shortness of breath, pulmonary congestion

  43. CLARE SHALDERS/GOTAFE/2008 Works by exerting a positive inotropic action on the heart > Increases the force of contraction and thereby improve the mechanical efficiency of the heart as a pumping organ >Results in a reduction in heart size >They also slow heart rate and slow conduction >Increases blood flow to the kidneys

  44. CLARE SHALDERS/GOTAFE/2008 Example – Most widely used Digoxin (Lanoxin) Increases the amount of calcium inside the cells of the heart and caused the heart muscle to beat stronger Loading doses are used to start therapy Regular blood tests to ensure therapeutic dose Low therapeutic index ie. Therapeutic dose is close to toxic dose Symptoms of toxicity GIT upset – N&V, diarrhoea Neurological – Drowsiness, confusion, lethargy Cardiac arrythmias Hypokalaemia (low K) Renal impairment

  45. CLARE SHALDERS/GOTAFE/2008 Nursing Implications Close monitoring to look for signs of toxicity Narrow therapeutic range Regular serum digoxin levels Caution is required when patient is taking Quinidine and Digoxin as quinidine enhances digoxin Look up digoxin

  46. CLARE SHALDERS/GOTAFE/2008 Heart Failure Medications Usually treated with Diuretics ACE Inhibitors Beta blockers Digoxin

  47. CLARE SHALDERS/GOTAFE/2008 Heart Failure Diuretics Used to remove excess fluid Minimise shortness of breath and swelling ACE Inhibitors Dilate blood vessels making it easier for the heart to pump blood Improve symptoms and can prolong survival If ace inhibitors not tolerated combination of nitrates and hydralazine can be substituted

  48. CLARE SHALDERS/GOTAFE/2008 Heart Failure Heart failure patients often have high levels of adrenaline in their blood stream Beta blockers block this adrenaline effect Metoprolol was the first beta blocker for this indication Carvedilol beta blocker with other properties that was specifically developed for patients with heart failure Digoxin strengthens the heart muscle to improve the symptoms of heart failure Spironolactone a diuretic inhibits hormone called aldosterone that is deleterious to the failing heart in addition to its fluid removing effects.

  49. CLARE SHALDERS/GOTAFE/2008 Antihypertensive agents Hypertension is defined as an abnormal increase in arterial blood pressure Blood pressure is dependant on two factors > Cardiac output and peripheral resistance Virtually all forms of antihypertensives affect one or both of these systems There are several types Beta bockers Alpha blocker Diuretics Angiotensin converting enzyme (ACE inhibitors) Calcium channel blocker

  50. CLARE SHALDERS/GOTAFE/2008 Antihypertensives Antihypertensive agents act indirectly such as vasodilators or directly such as angiotensin converting enzyme (ACE) They treat by improving blood volume, cardiac output.