Transcript Adult Medical –Surgical Nursing 1

Adult Medical-Surgical Nursing
CARDIOVASCULAR MODULE:
DYSRHYTHMIAS
Dysrhythmias
 Dysrhythmias are disorders of:
 Formation (and/ or)
 Conduction of electrical impulses through the heart
Normal Conduction
 Impulses arise in the SA node (physiological
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pacemaker of the heart) →
AV node →
Bundle of His →
Left and right bundle branches →
Purkinje fibres
Impulses stimulate depolarisation of the myocardial
cells
Dysrhythmias: Classification
 Sinus tachycardia (> 100/ min)
 Sinus bradycardia (< 60/ min)
 Atrial flutter
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} (supraventricular
Atrial fibrillation } tachycardia)
First, second, third degree block
Ventricular tachycardia
Ventricular fibrillation
Asystole
Dysrhythmias: Aetiology
 Congenital anomalies
 May occur as a complication:
 Post myocardial infarction
 Post cardiac surgery
 In relation to acid/ base imbalance
 In relation to electrolyte/ mineral imbalance
Dysrhythmias: Pathophysiology
 Disorganised stimulation of the myocardial cells
leads to:
 ↓ cardiac output
 ↓ BP
 Inadequate perfusion
 An ineffective cardiac pump, inco-ordinated and
weak
Pathophysiology (Tachycardia)
 If tachycardia presents:
 Inadequate repolarisation and insufficient filling
time (↓ refractory period) leads to:
 ↓ contractility and ↓ cardiac output
 ↓ filling of coronary arteries: can cause myocardial
infarction (MI)
Pathophysiology (Bradycardia)
 If bradycardia presents:
 The heart rate is insufficient to maintain cardiac
output
Pathophysiology (Fibrillation)
 Where fibrillation occurs:
 There is risk of thrombus and emboli leading to:
 Cerebral → stroke
 Peripheral → arterial occlusion and ischaemia
Dysrhythmias: Clinical Manifestations
 Chest pain and tightness
 Dyspnoea
 Palpitations
 Faintness/ dizziness
 (may lead to loss of consciousness from ↓ cardiac
output)
 Hypotension
 Weak pulse (fast or slow; regular or irregular)
Dysrhythmias: Diagnosis
 Patient history
 Clinical examination
 ECG/ cardiac monitoring
Dysrhythmias: Management
 Medications
 Pacemaker
 Catheter ablation therapy
 Cardioversion/ defibrillation
Medications
 Drugs to increase contractility and slow heart rate:
 Cardiac glycosides
 β-blockers
 Calcium-channel blockers
 Vasopressin (ADH) (symptom relief)
Medications
 Drugs to increase the refractory period (diastole):
 Drugs aim to allow adequate filling and coronary
perfusion
 Amiodorone is such a drug of choice
Medications
 Drugs to correct bradycardia:
 Inhibit parasympathetic (vagal) activity on the SA
node
 Atropine most commonly used
Medications
 If fibrillation present:
 Drugs to reduce the risk of thrombus formation and
emboli
 Anticoagulants or
 Anti-platelet aggregates
Pacemaker
 A pacemaker is a generator with a battery and leads
used to stimulate the SA node at a regular normal
rate
Pacemaker
 Used for bradycardia (and sometimes atrial
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fibrillation)
Promotes adequate cardiac output
A pacemaker:
Senses the heart rate
Regulates the heart rate
Implanted defibrillator used if risk of ventricular
fibrillation
Types of Pacemaker
 Temporary: used following MI or cardiac surgery if
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dysrhythmia arises
Permanent:
External (battery outside the skin)
Internal (implanted under the skin)
Within endocardium of right ventricle
 Implanted cardioverter defibrillator (ICD): detects/
corrects Ventricular Fibrillation (VF) and Ventricular
Tachycardia (VT)
Pacemaker: Instructions to Patients
 Carry a card with the details
 Avoid MRI
 Avoid holding a mobile phone close to pacemaker
 Avoid electronic security scanners
 Will require battery change
Catheter Ablation Therapy
 Used in some cases of tachydysrhythmia
 Follows an electro-physiological study (EP) to
evaluate dysrhythmia
 Performed under light sedation
 Ablation (destruction) of the specific cells
responsible for mal-conduction
 Radiofrequency, cryoablation or electrical ablation
used
Cardioversion and Defibrillation
 An electrical shock to the myocardial cells intended
to restart sinus rhythm from the SA node
 Used for dysrhythmias with increased heart rate not
responding to medication
 Defibrillation as emergency action
Cardioversion
 An elective procedure
 Patient is fasting under conscious sedation
 Anticoagulation prior to procedure
 Shock is programmed with the QRS complex (R
wave) of the ECG
Defibrillation
 An emergency procedure (VT or VF)
 The heart muscle must have some activity before
defibrillation
 CPR is performed to stimulate activity (not to be
used in asystole)
Nursing Considerations
 Ensure correct drugs and monitor effect
 Ensure patient awareness about medication
 Specific advice on anticoagulant therapy
 Special precautions for a patient with a pacemaker
 Assist and monitor patient during cardioversion or
defibrillation