Adult Medical-Surgical Nursing

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Adult Medical-Surgical Nursing

• Atherosclerosis and Coronary Heart Disease

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Reduced Blood Flow to Cardiac Muscle

• Conditions reducing blood flow to cardiac muscle
  are
• Atherosclerosis of coronary arteries
• Acute vasospasm (vasoconstriction)
• Hypotension
• Acute blood loss
• Severe anaemia ? O2 supply
• Congenital anomaly (ASD VSD)
• ? O2 demandThyrotoxicosis, cocaine abuse,
  exercise

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• Atherosclerosis

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Atherosclerosis Description

• An abnormal accumulation of lipid (fatty)
  deposits and fibrous tissue within the arterial
  blood vessel walls
• May affect all arteries of the body
• Narrows the lumen
• Leads to reduced blood flow (? O2 and nutrients
  to the tissues) ischaemia
• May cause infarction of affected area (tissue
  death)

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Atherosclerosis Aetiology

• Non-modifiable risk factors
• ? risk with age (especially after 65 years)
• Males and post-menopausal women more at risk
  (oestrogen protects)
• Family history genetic tendency

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Atherosclerosis Aetiology

• Modifiable risk factors
• Cholesterol abnormality (? blood lipids) related
  to
• Diet ? animal fats (LDL) and ? vegetable and
  fish oils (HDL)
• Salt intake (BP)
• Obesity, lack of exercise
• Smoking
• Hypertension/ Diabetes Mellitus

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Atherosclerosis Pathophysiology

• Lipids are deposited on the intima of the
  arterial wall
• Inflammatory response phagocytosis by killer
  T-lymphocytes and macrophages
• Smooth muscle cells form a fibrous cap over the
  dead fatty lesion plaque/ atheroma
• Plaque protrudes, narrowing the arterial lumen
• Increases pressure in the lumen
• Obstructs oxygenated blood flow
• ? ischaemia of tissue supplied
• Prolonged ischaemia ? infarction

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Thrombus Formation

• The arterial blood flow under pressure ruptures
  the fibrous cap (of the plaque) if thin ?
• Haemorrhage
• ? clot/ thrombus (platelet aggregation on the
  damaged wall)
• May completely obstruct artery
• ? ischaemia and infarction

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Atherosclerosis Prevention

• Diet ? intake of HDL (vegetable and fish oils)
  and ? LDL (animal fats)
• Restrict salt intake
• Exercise and weight control
• Stop smoking
• Antilipid medication
• Vasodilators
• Anti-platelet aggregate

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• Coronary Atherosclerosis

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Coronary Atherosclerosis Description

• Atherosclerosis of the coronary arteries which
  supply oxygenated blood to the myocardium
• Coronary arteries are more at risk of
  atherosclerosis and narrowing because they twist
  and turn
• A progressive narrowing of the lumen reduces
  blood flow ? ischaemia will eventually lead to
• Myocardial Infarction

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Coronary Atherosclerosis Diagnosis

• ECG
• Stress ECG
• Cardiac catheterisation
• Chest Xray
• Echo cardiogram
• Blood chemistry, lipids, ABG, LFT, KFT, glucose,
  coagulation, CBC
• Cardiac enzymes (to exclude infarct)

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Coronary Atherosclerosis

• Coronary atherosclerosis is characterised by
• Angina
• Coronary Thrombosis and Myocardial Infarction

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• Angina

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Angina

• Chest pain (Angina Pectoris) is a condition
  describing the pain experienced from myocardial
  ischaemia
• Acute and severe gripping sub-sternal or
  retro-sternal pain radiating to the axillae, neck
  or jaw

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Angina Classification

• Stable Angina
• Chest pain on exertion
• Usually lasts 5 - 15 minutes
• Relieved by rest or medication
• Unstable Angina
• Chest pain at rest
• Occurs frequently/ lasts longer
• Only relieved by medication
• Often precedes Myocardial Infarction

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• Myocardial Infarction (MI)
• (An acute emergency situation)

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Myocardial Infarction Description

• Myocardial Infarction death of cardiac muscle
  tissue resulting from ischaemia (most often
  related to coronary thrombosis other causes
  slide 2)
• Infarcted myocardial cells release enzymes and
  proteins through the destroyed cell wall ?
  cardiac enzymes in the blood circulation
• Infarction interferes with normal myocardial
  function causing weakness and maybe irregularity

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Myocardial Infarction Outcomes

• Myocardial scarring and weakness
• Poor conduction of electrical impulses ?
  dysrhythmias and weak cardiac output (can lead to
  cardiogenic shock)
• Unaffected heart muscle has excess work to
  achieve adequate cardiac output ?
• Cardiomegaly
• Cardiac failure

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Myocardial Infarction Clinical Manifestations

• Chest pain (Angina)
• Acute, sub-sternal, radiating to shoulders and
  possibly hands
• Prolonged, unresponsive to vasodilators
  (medication for angina)
• Nausea, vomiting, pallor, sweating (cold, clammy
  skin), hypotension, rapid, thready weak pulse
  shock
• Dyspnoea, dizziness, restlessness, anxiety

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Myocardial Infarction Diagnosis

• History and clinical picture
• 12-lead ECG reveals site and degree of ischaemia/
  infarction
• Continuous monitoring
• Cardiac enzymes (? if infarction) (see slide 22)
• Blood chemistry, lipids, ABG, LFT, KFT, glucose,
  coagulation, CBC
• Cardiac catheterisation

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Cardiac Enzymes

• Creatinine-kinase (CKMB specific)
• Lactic Dehydrogenase (LDH 1)
• Troponin 1
  
• Myoglobin (myo-haemoglobin)
• (raised when infarction has occurred)

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Myocardial Infarction Acute Management

• Analgesia IV Morphine
• ECG/ continuous monitoring
• Humidified O2 with high flow rate
• Anti-platelet aggregate
• Vasodilator Nitroglycerin
• Anticoagulant Heparin
• Thrombolytic agent (within 30 mins)
• Cardiac catheterisation Urgent Coronary
  Angioplasty (PTCA) and Stent to maintain patency
  (treatment of choice).

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Surgery for Coronary Atherosclerosis

• Angioplasty (PTCA) Removal of plaque and
  insertion of stent(s) to maintain patency
• Anti-platelet aggregate prescribed for several
  months post-stent
• Patient with severe atherosclerosis may require
  Coronary Artery Bypass Graft (CBG) using graft
  from
  
• The deep saphenous vein
• The internal mammary arteries

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Nursing Considerations

• Patient education about condition, diet and
  weight control, exercise, smoking
• Ensure medications understood including
  precautions and monitoring for anticoagulant/
  anti-platelet therapy
• Emergency care in ICU if admitted with chest pain
• Awareness and competence in administering
  medications
• Psychological/ emotional support