pharmacology dysrhythmias 2

Pharmacology

DysrhythmiasChapter 24

Dysrhythmias

• The electrical or conduction system controls the sequence of muscle contraction for optimal blood volume pumped from the heart each beat

Dysrhythmias

• Sometimes called arrhythmia• Occurs when there is a disturbance of the normal

electrical conduction• Results in abnormal heart muscle contraction• Results in abnormal heart rates• The dangers is the frequency with which they occur• An inefficient pumping of adequate volume of blood• Certain type can produce additional dysrhythmias

Dysrhythmias

• Certain type can produce additional dysrhythmias– the heart stops pumping and still beat for a short

time--fibrillations

Dysrhythmias Classification

• Origin within heart tissue– Electrical impulse sequence– Obstruction of conduction pathway– Combination– Based on heart beat rate

Dysrhythmias

• Causes:• Firing of abnormal pacemaker cells is when

something causes out of regularity of electrical impulse (sequence)—irregular muscular contraction

• Blockage of normal electrical pathways is a partial obstruction of normal conduction pathway causing an irregular pattern of muscle contractions—reentrant dysrhythmia

• Combination of the both

Sequential Causes

• Above the Bundle of His—Supraventricular– Atrial flutter– Atrial fibrillation– Premature atrial contraction PAC’s– Sinus tachycardia– Sinus bradycardia– Paroxysmal supraventricular tachycardia

Sequential Causes

• Developing near or within the AV node are:– Junctional dysrhythmias

• Developing below the Bundle of His are:– Ventricular dysrhythmia– Premature ventricular contractions—PVC’s – Ventricular tachycardia—VT – Ventricular fibrillation—VF

Obstruction Causes

• Described by location• Supraventricular• Ventricular• Left or right bundle branches• Atrio-ventricular blocks– Sub-classifications– 1st degree—partial block, delayed AV conduction– 2nd degree—partial block, with occasional blocked beats– 3rd degree—complete block

• atria & ventricles function independent

Dysrhythmias: Diagnosis

• Physical examination• History• ECG pattern—underlying cause***

Treatment of Dysrhythmias

• The goal of therapy:• Restore normal sinus rhythm• Restore normal cardiac function• Prevent recurrence of life-threatening

dysrhythmias

Dysrhythmias: Drug Therapy

• Anti-dysrhythmic are classified according to their effect on the electrical conduction system

• Class Ia-IV– Sodium Channel Blockers (intermediate acting)– Sodium Channel Blockers (quick acting)– Sodium Channel Blockers (slow acting)– Beta Adrenergic Blockers– Potassium Channel Blockers– Calcium Channel Blockers– Vagal Stimulators– Conduction Slowers


• Class• Ia• Ib• Ic• II• III• IV• Misc.


• Class I act as myocardial depressant by inhibiting sodium ion movement


• Class Ia prolong duration of the electrical stimulation on cells & refractory time between electrical impulses

• Sodium Channel Blockers (intermediate acting)

• Quinidine• Procainamide • Disopyramine


• Class Ib shorten the duration of electrical stimulation & time between electrical impulses

• Sodium Channel Blockers (quick acting)• Lidocaine• Mexiletine


• Class Ic are the most potent myocardial depressant & slow conduction rate through atria and ventricles

• Sodium Channel Blocker (slow acting)• Flecainide• Propafenone


• Class II are BAB agents that depress the stimulation of beta cells of the SNS

• Beta Blockers• Propranolol• Esmolol• metoprolol


• Class III slow the rate of electrical conduction & prolong the time interval between contractions by blocking potassium channels

• Potassium Channel Blockers• Amiodarone• Sotalol• Ibutilide• dfetilide


• Class IV block calcium ion flow, prolonging duration of the electrical stimulation & slowing AV node conduction

• Calcium Channel Blockers• Verampamil• Diltiazem


• Misc Anti-dysrhythmia Agents• Digoxin—vagal stimulator• Adenosine—conduction slower

Nursing Process: Dysrhythmias

• Analysis & Diagnosis• Assess ECG• Telemetry in place as adjunct• 24 hour ECG Holter monitor• EPS - electrophysiologic studies• Exercise electrocardiography• Lab & DIAGNOSTIC TESTS: K+, Ca+, ABG, clotting: AST, ALT, CK-MB, creatinine

troponin, D-diameter, LDH, X-ray, cardiography, catherization• Examine urinalysis & perform hourly I & O’s • Report < 30-50mL urine output• Monitor renal function—BUN and creatininte• Medical history—meds prescribed• 6 Cardinal Signs of CVD (dyspnea, chest pain, fatigue, edema, syncope, palpitations• Mental status: LOC, clarity of thought—cerebral perfusion• VS: BP twice daily, record BP in both arm 5-10 mm Hg or more reported, HR, RR,

temperature, O2 sat, BrS• Auscultation & Percussion for heart size and sounds


• Decreased Cardiac Output• Activity Intolerance• Risk for Decreased Cardiac Tissue Perfusion• Fatigue• Death Anxiety


• Planning:• Order medication & place in the MAR• History of 6 Cardinal Signs of CVD• Basic Mental Status once per shift• VS, Auscultation & Percussion schedule consistent

with client’s status• Lab test order stat & subsequent labs; monitor

result• Emergency treatment: “codes”—cardioversion

and defibrillation


• Implementation:• Monitor ECG telemetry• Perform physical assessment (Q4-8 hr)• Assist with ADL’s, note the degree of impairment or

dyspnea w/or w/o exertion• O2 as ordered or PRN• Administer prescribed meds & ACLS protocol to best

alleviate symptom for maximum comfort• Encourage physical activity• Measure to reduce anxiety


• Education & Health Promotion:• Identify modifiable factors• Design approach to modify factors within

client’s control• Teach, Discuss & Practice coping mechanism

to handle anxiety• Teach to take pulse rate, blood pressure, signs

& symptoms

Nursing Process: Dysrhythmias• Fostering Health Maintenance:• Discuss med information & how it will benefit• Discuss meds should be taken as prescribed• Provide client & significant other w/important information from drug

monograph• Teach drug adverse effects and how to respond• Seek cooperation & understanding of:• Name of med• Dosage• Route• Times• Common and Serious adverse effects


• Written Record:• Enlist client’s aid in developing & maintaining a

written record• Monitoring parameter to include like HR, BP,

degree of dyspnea & precipitating causes, chest pain, edema

• Ensure client know how to use form• Instruct client to bring completed form to

follow up visits

pharmacology dysrhythmias 2

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