3a atrial rhythms

Atrial RhythmsAtrial Rhythms

Electrical impulses that originate from the atrium (not from the SA node).

Wandering Atrial Pacemaker Wandering Atrial Pacemaker (WAP)(WAP)

Rhythm: Slightly Irregular

Rate: Usually 60 – 100 bpm; sometimes slower

P waves: Morphology of each P wave differs

PRI: 0.12 – 0.20 sec; inconsistent

QRS: Narrow (< 0.12 sec); sometimes wide

Wandering Atrial Pacemaker Wandering Atrial Pacemaker (WAP)(WAP)

Causes:

Increased vagal effect on the sinoatrial node, slowing the sinus rate and allowing other pacemaker sites an opportunity to compete for control of the heart rate

It is a normal phenomenon in young healthy hearts (especially those of athletes)

Coughing may decrease vagal tone and encourage reappearance of a sinus rhythm

Premature Atrial Contraction (PAC) Premature Atrial Contraction (PAC)

A premature atrial contraction (PAC) is an early beat that occurs when an ectopic site within the atria discharges

an impulse before the sinus node impulse is discharged.

Ectopic site is speeding up in an attempt to take over as the pacemaker – irritability; (or the SA node has slowed

down)

Can originate from one ectopic site or from multiple sites in the atria.

PAC PAC If the ectopic site is near the SA node, the

appearance of the P wave may closely resemble the sinus P wave

Most often the P wave morphology of the PAC is significantly different from that of the sinus P

wave

Sometimes with very premature PAC’s, the P wave is hidden within the T wave of the

previous complex

PAC with Aberrant PAC with Aberrant Ventricular ConductionVentricular Conduction

PAC with Aberrant Ventricular Conduction

An early beat from an atrial site (other than the SA node) that is abnormally conducted

through the ventricles

Causes a change in the morphology of the QRS complex

(Example on p. 96)

Non-Conducted PACNon-Conducted PAC

P wave of PAC is not followed by a QRS complex

AV node is refractory and is unable to respond to the electrical stimulus

P wave is followed by a pause

P wave may be hidden in the T wave (changes morphology of the T wave) - May be confused with a block/arrest

(example on p. 99)

Compensatory vs. Compensatory vs. NoncompensatoryNoncompensatory

PAC’s are followed by a pause

What makes it compensatory versus noncompensatory???

(Overhead slide 3-1)

Premature Atrial Contraction Premature Atrial Contraction (PAC)(PAC)

Rhythm: Depends on the underlying rhythm; Premature ectopic beat causes slight irregularity

Rate: Overall HR depends on rate of underlying rhythm

P waves: P wave of premature beat will have a different morphology (flattened, notched, or unusual). May be hidden in

the T wave

PRI: 0.12 – 0.20 sec on regular beat; ectopic beat PRI may differ.


Supraventricular TachycardiaSupraventricular Tachycardia(Paroxysmal Atrial Tachycardia)(Paroxysmal Atrial Tachycardia)

May occur as a basic rhythm or within an underlying rhythm (burst of SVT or PAT)

3 or more consecutive PAC’s with a rate of 140 – 250 is considered to be a burst of SVT or PAT

(example on p. 100)


SVT/PAT may be a result of emotional stress, ingestion of caffeine, tobacco, or alcohol

Other causes:

COPD

Digitalis Toxicity


During episodes of SVT/PAT, patient may experience the following s/s:

Hypotension

Decreased LOC

Palpitations

Chest Pain

S.O.B.


Treatment involves controlling the ventricular rate in order to maintain adequate CO

Vagal Maneuvers

Adenosine, BB’s, CCB’s, digitalis

Antiarrhythmics (amiodarone)

IV Fluid Bolus

Electrical Cardioversion

SVT or PATSVT or PAT

Rhythm: Regular

Rate: 150 – 250 bpm

P waves: None (May be hidden in T wave); If present will have abnormal appearance

PRI: None or normal if P wave is present


Atrial FlutterAtrial Flutter

Begins from one specific foci in the atrium. These atrial contractions are less rapid and more organized (than a-

fib) resulting in an atrial rate of 250 – 400 (Davis, 2004), (Huff, 2006)

Rapid stimulation/depolarization of the atrial muscles causes production of waveforms that resemble the

teeth of a saw

The sawtooth deflections are known as Flutter Waves


Sometimes the flutter waves have a softer appearance and appear as “clouds”

(Example on p. 112, Strip 7-16)

Atrial firing is continuous; does not stop while impulses are traveling through the ventricles

Ventricular rate is controlled by AV node (the gatekeeper)


Conducted by ratios (example above: every 3rd

impulse is conducted = 3:1 AV conduction)

Sometimes the ratio is not constant = variable AV conduction

(example on p. 103, Figure 7-18)

Atrial Flutter with Varied Atrial Flutter with Varied ResponseResponse


If ventricular heart rate is less than 100 =

Controlled A-flutter

or

A-flutter with controlled ventricular response


If ventricular heart rate is greater than 100 =

Uncontrolled A-flutter

or

A-flutter with RVR (rapid ventricular response)


3:1 ResponseRhythm: Regular or irregular; depends on ventricular

response

Rate: Atrial 250 – 400 bpm; ventricular rate depends on AV conduction

P waves: Sawtooth/Cloud appearance

PRI: Unable to be measured


Atrial FibrillationAtrial Fibrillation

It is the most common rhythm next to sinus rhythm

Is a result of various ectopic sites within the atria that are firing at a rate

of 400 – 600 bpm


Rapid depolarization of various sites causes the atria to quiver =

fibrillatory waveforms

Some of the atrial firing does not go to the AV node; remains in the same

place and only depolarizes that small area


Fib-Flutter waves

Flutter waves mixed with fibrillatory waves between the

QRS complexes

(Example on p. 111, Strip 7-14)

Atrial FibrillationAtrial FibrillationMay produce fine fibrillatory waves or

coarse fibrillatory waves

Coarse fibrillatory waves are “very wavy”

Fine waves are so small that they may appear as flat lines between the QRS’s

(example on p. 105, Figure 7-22)


Atrial firing is continuous; does not stop while impulses are traveling through the

ventricles

Ventricular rate is controlled by AV node (the gatekeeper)

Goal is to control the AV conduction to the ventricles


If ventricular heart rate is less than 100 =

Controlled A-fib

or

A-fib with controlled ventricular response)


If ventricular heart rate is greater than 100 =

Uncontrolled A-fib

or

A-fib with RVR (rapid ventricular response)


Rhythm: Irregular

Rate: Unable to measure atrial; ventricular depends on AV conduction

P waves: Fibrillatory waves (coarse or fine); chaotic

PRI: Unable to be measured


A-Fib & A-FlutterA-Fib & A-FlutterCommon Causes:

Valvular Heart Disease (especially with mitral valve)

Hypertensive Heart Disease

CAD

Pulmonary Emboli

Hyperthyroidism

S/P Cardiac Surgery

A-Flutter & A-FibA-Flutter & A-FibTreatment involves converting the rhythm

and/or controlling the ventricular rate in order to maintain adequate CO, in

addition to prevention of blood clots

BB’s, CCB’s, digitalis

Antiarrhythmics (amiodarone)

IV Fluid Bolus

Anticoagulants

Electrical Cardioversion

A-Fib with controlled ventricular response

Rate:Rhythm: P wave:

QRS:

Approx. 90 bpmIrregular

None0.04 sec

Analyze the Following:

TIME TO WORKOUT!!!TIME TO WORKOUT!!!

ReferencesReferencesChernecky, C., et al. (2002). Real world nursing survival guide:

ECG’s & the heart. United States of America: W. B. Saunders Company.

Huff, J. (2006). ECG workout: Exercises in arrhythmia interpretation (5th ed.). United States of America: Lippincott, Williams & Wilkins.

Walraven, G. (1999). Basic arrhythmias (5th ed.). United States of America: Prentice-Hall, Inc.

www.madsci.com/manu/ekg_rhy.htm

3a atrial rhythms

Health & Medicine

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