Pt 3 Atrial Dysrhythmias

Question 1

• PAC
• PSVT

Answer 1

• Atrial fibrillation
• Atrial flutter

Question 2

In pts w/atrial dysrhythmias, focus of impulse generation shifts away from sinus node to the atrial tissues

• Shift changes axis of atrial depolarization changing P wave shape

Question 3

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• Contraction originating from ectopic focus in atrium in location other than SA node
• Travels across atria by abnormal pathway, creating distorted P wave
• May be stopped, delayed, or conducted normally @ the AV node

Answer 3

Premature atrial contraction (PAC)

Question 4

PAC Causes

• Stress, fatigue, caffeine, tobacco
• Alcohol, hypoxia

Answer 4

• Electrolyte imbalances
• Dz states (hyperthyroidism, COPD, heart dz like CAD & valvular dz)

! In persons w/healthy hearts, isolated PACs aren’t significant

Question 5

Manifestations

• Palpitations
• Heart “skips a beat”

Answer 5

Treatments

• Monitor for more serious dysrhythmias
• Withhold sources of stimulation
• B-adrenergic blockers

! Premature complexes are early beats from an ectopic focus, followed by a pause before the next complex

Question 6

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Is a dysrhythmia starting in ectopic focus anywhere above the bifurcation of the bundle of His

ID’ing difficult even w/a 12-lead ECG as needs recording of dysrhythmia as it starts

HR 150-220 bpm
Rhythm: regular or slightly irregular
P wave hidden in preceding T wave; may have an abn shape if seen
PR interval shortened or normal
QRS complex usually normal

Answer 6

Paroxysmal Supraventricular Tachycardia (PSVT)

Question 7

• Re-entrant phenomenon: PAC triggers a run of repeated premature beats
• Paroxysmal refers to an abrupt onset & termination

Answer 7

• Assoc w/overexertion, stress, deep inspiration, stimulants, rheumatic heart dz, digitalis toxicity, CAD, & cor pulmonale

Question 8

PSVT - Manifestations

• HR is 150-220 bpm
• HR >180 leads to dec CO & SV
• Hypotension
• Dyspnea
• Angina

Answer 8

Treatments

• Vagal stimulation (Valsalva, carotid massage, coughing)
• IV adenosine (1st choice rx)
• IV B-adrenergic blockers [sotalol]
• Calcium channel blockers [diltiazem]
• Amiodarone
• Direct current (DC) cardioversion

Question 9

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Is an atrial tachydysrhythmia identified by recurring, regular, sawtooth-shaped flutter waves that originate from a single ectopic focus in the right atrium or less commonly, left atrium

Rate 200-350 bpm
Atrial rhythm regular, ventricular rhythm usually regular
PR interval variable & not measurable
QRS complex usually normal

Answer 9

Atrial Flutter (aka sawtooth pattern)

Question 10

Treatments

• Assoc w/CAD, HTN, mitral valve disorders, PE, chronic lung dz, cor pulmonale, CM, hyperthyroidism, & rx’s like digoxin, quinidine, & epinephrine
• Sx’s result from high ventricular rate & loss of atrial “kick” -> dec CO -> HF

Answer 10

• Inc risk of stroke b/c risk of thrombus formation in the atria from stasis of blood
  > Warfarin (Coumadin) is given to prevent stroke in pts w/a-flutter

Question 11

• Primary goal is to slow the ventricular response by inc AV block; rx’s such as calcium channel blockers & B-adrenergic blockers
• Antidysrhythmic rx’s convert a-flutter to sinus rhythm (ibutilide) or to maintain sinus rhythm (amiodarone, flecainide, dronedarone)

Answer 11

• Electrical cardioversion may be performed to convert a-flutter to sinus rhythm in an emergency & electively
• Radiofrequency ablation (done in EP lab) is the treatment of choice for a-flutter

Question 12

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Is characterized by a total disorganization of atrial electrical activity d/t multiple ectopic foci resulting in loss of effective atrial contraction

Answer 12

Atrial fibrillation

Question 13

Atrial rate may be as high as 350-600 bpm

• P waves replaced by chaotic, fibrillatory waves
• Ventricular rate varies & the rhythm is usually irregular

Answer 13

• PR interval is not measurable & QRS complex usually has normal shape & duration
• At times, a-flutter & afib may coexist

Question 14

Atrial Fibrillation

• Paroxysmal or persistent
• Most common dysrhythmia (in regards to M&M rates & economic impact)
• Prevalence inc w/age

Answer 14

• Usually occurs in pts w/underlying heart dz (CAD, RHD, CM, htn-HD, HF, pericarditis)
• Can also occur w/other dx states (acutely w/thyrotoxicosis, alcohol intoxication, caffeine use, electrolyte disturbances, stress, & cardiac surgery)

Question 15

• Causes a dec in CO (b/c ineffective atrial contractions &/or a rapid ventricular response) & an inc risk of stroke (thrombi develop in the atria b/c of blood stasis)

Answer 15

Treatment

• Rx’s to control ventricular rate &/or convert to sinus rhythm (amiodarone & ibutilide most common)
• Electrical cardioversion
• Anticoagulation
• Radiofrequency ablation
• Bi-ventricular pacing
• Maze procedure w/cryoablation

Question 16

! Dec in ventricular rate to <100 bpm
! Prevention of stroke
! Conversion to sinus rhythm, if possible

Answer 16

! If a pt is in atrial fibrillation for longer than 48 hrs, anticoagulation therapy w/warfarin is needed for 3-4 wks <the cardioversion & for several wks >the successful cardioversion

! If rx’s or cardioversion do not convert atrial fibrillation to normal sinus rhythm, long-term anticoagulation therapy is required. Warfarin is the rx of choice, & pts are monitored for therapeutic lvls (i.e., INR)

Question 17

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Is a surgical intervention that stops atrial fibrillation by interrupting the ectopic electrical signals that are responsible for the dysrhythmia

Incisions are made in both atria, & cryoablation (cold therapy) is used to stop the formation & conduction of these signals & restore normal sinus rhythm

Answer 17

Maze procedure