Cardiac Rhythms

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This is a short course provided to nurses, EMT's, Paramedics, and any other health professional looking to review their Cardiac Rhythms

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By: nadsab (14 month(s) ago)

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Presentation Transcript

Slide 1:

Student ECG Cardiac Rhythms Presents

Slide 2:

SUPRAVENTRICULAR RHYTHMS

Slide 3:

Normal Sinus Rhythm • Normal sinus rhythm is the normal heart rhythm characterized by p waves emanating from the sinus node, upright in II, III, and aVF, and at a rate from 50 to 90. • Under normal circumstances there is slight irregularity due to autonomic fluctuation with respiration. Loss of this variability could signify autonomic dysfunction.

Slide 4:

Sinus Tachyardia and Bradycardia • Sinus tachycardia is defined as a sinus rhythm at a rate greater than 90. It can get as high as 200 bpm with exercise, but otherwise rarely exceeds 150 bpm. Causes are numerous; treatment is aimed at the underlying cause. • Sinus bradycardia is a sinus rhythm at a rate less than 50. It may be physiologic, such as during sleep, with highly trained athletes, from numerous medications. In general treatment may be necessary if the heart rate while awake is < 40 or if >40 and the patient has symptoms

Slide 5:

Sinus Arrhythmia • Normally the heart rate accelerates with inspiration and slows with expiration. • In sinus arrhythmia this can be exaggerated, especially in children. • The intervals remain constant, and the rhythm is mildy irregular.

Slide 6:

Ectopic Atrial Rhythm • The focus of depolarization is somewhere in the atrium, not the sinus node. Therefore the p-wave axis is usually abnormal. • On the ECG, P waves are often inverted in II, III, and aVF, where they are normally upright, yet they are constant and regular. • The PR interval may be short if the focus is close to the AV node.

Slide 7:

Ectopic Atrial Rhythm P waves are inverted, but intervals are constant and the rhythm is regular

Slide 8:

Ectopic Atrial Rhythm The cause of an ectopic atrial rhythm is usually increased automaticity in the atria (Increased spontaneous depolarization).

Slide 9:

Wandering Atrial Pacemaker • In wandering atrial pacemaker, there are differing foci of depolarization in the atrium other than the sinus node. • On the ECG the P waves will be of varying morphologies: some pointed, double peaked, inverted, etc. • There should be at least 3 different morphologies apparent. • Because of differing distances from the AV node, the P-R intervals will also vary. • The rhythm is irregular with a rate less than 100.

Slide 10:

Wandering Atrial Pacemaker Differing P waves; rhythm is irregular • WAP usually occurs in patients with sinus node dysfunction, atrial abnormalities, increased vagal tone to the SA node, and in normals during sleep. • No treatment is required.

Slide 11:

Multifocal Atrial Tachycardia • MAT is similar to wandering atrial pacemaker, except the rate is above 100 bpm. • Not infrequently, the atrial depolarizations will come early and be blocked due to the refractory period of the AV node. They may also be buried in the T wave, causing changes in its morphology. • MAT is most often associated with severe pulmonary disease, CHF, etc.

Slide 12:

Multifocal Atrial Tachycardia Different P Wave morphologies Very early P wave hidden in T wave

Slide 13:

Supraventricular Tachycardia (SVT) • Most are AV nodal reentrant tachycardias (AVNRT), occurring in or around the AV node. • Mechanism: when a PAC hits the AV node at the right moment, it can initiate a re-entrant circuit resulting in AVNRT. • Usually conduction proceeds down a fast pathway and back up a slow pathway, which has a unidirectional block of antegrade impulses.

Slide 14:

AVNRT Mechanism 1. Atrial Impulse AV Node Slow Pathway blocked 2. PAC enters ( PAC ) Slow pathway recovers first; fast still refractory 3. Re-entry Fast pathway then recovers and conducts retrograde (final common pathway)

Slide 15:

AVNRT • Less frequently conduction proceeds in the reverse order • Reentrant circuits can occur with pathways outside the AV node.

Slide 16:

SVT (AVNRT) • ECG manifestations: • Narrow complex regular tachycardia usually > 160 bpm • P waves may: • Be absent (most) • Just follow the QRS-often inverted • Just precede the QRS(unusual)

Slide 17:

SVT (AVNRT) Carotid Massage “ Usual” AVNRT with a rapid, narrow complex QRS and no discernable P waves. Conversion to NSR occurs with carotid massage.

Slide 18:

SVT (AVNRT) Notice the small impulse just after the QRS, which is a retrograde P wave

Slide 19:

SVT- Treatment • Acute treatment is with vagal maneuvers like carotid massage or valsalva • Drug therapy-adenosine, verapamil, beta blockers, sometimes other antiarrhythmics • AV nodal ablation is definitive therapy and may be the therapy of choice as meds are only modestly effective.

Slide 20:

Atrial Flutter • This is a reentrant type of arrhythmia that occurs in the atria. • Instead of discreet p waves, flutter or “F” waves are seen, typically at a rate close to 300. • They are best seen in leads II, III, aVF, and they are conducted to the ventricles at a slower rate due to the longer refractory period of the AV node. Typical conduction is 2:1, 3:1, 4:1, etc. The flutter waves may

Slide 21:

Atrial Flutter Saw-toothed flutter waves, best seen in lead II or III

Slide 22:

What is the rhythm? Always look at leads II, III and aVF to see P waves more clearly. It would be misleading by looking only at V1.

Slide 23:

2 to 1 Atrial Flutter Atrial Rate = 300; Ventricular Rate=150 fffff ff The rhythm starts out with a 2:1 atrial flutter, then the ratio changes. Every other flutter wave is buried in a QRS. Atrial flutter may be regular or irregular.

Slide 24:

Atrial Fibrillation • This rhythm results from chaotic random depolarization of the atria. • The most common associations are with ischemic, rheumatic, hypertensive heart disease, thyrotoxicosis, heart failure, and aging.

Slide 25:

Atrial Fibrillation • The ventricular conduction may be fast or slow, but shows an irregularly irregular pattern. • Atrial fibrillation may be coarse, with visible chaotic atrial activity, or fine, even to the point of almost no baseline activity.

Slide 26:

Atrial Fibrillation • From coarse(a) to fine(c) Q QRS complexes

Slide 27:

Fine Atrial Fibrillation Look closely; sometimes atrial fibrillation is barely irregular and can be confused with SVT or a junctional rhythm.

Slide 28:

Junctional Rhythm • AV nodal tissue can take over as the pacemaker of the heart, especially in the event of sinus node dysfunction. • A junctional rhythm is regular, and usually no p waves will be seen. They may be: • buried in the QRS complex, • occur afterwards during the ST segment, or be superimposed on the T waves. • just precede the QRS (rare).

Slide 29:

Junctional Rhythm

Slide 30:

Junctional Rhythm • The QRS width is narrow as conduction proceeds normally down the bundle branches, and the rate is approx. 40-60. • At higher rates, it is referred to as an accelerated junctional rhythm . When the rate is about 120 or greater, it is probably SVT. • Junctional rhythm is not re-entry like AVNRT, but is due to increased automaticity or failure of the SA node.

Slide 31:

Wolf-Parkinson-White In WPW there is an accessory bypass tract that directly connects the atrium to the ventricle. It is known as the bundle of Kent, and conducts without the delay seen in the AV node. This is know as pre-excitation.

Slide 32:

WPW The ECG manifestations are as follows: • 1. Short PR interval • 2. Delta wave (early abnormal ventricular depolarization). • 3. Widened QRS (due to the delta wave).

Slide 33:

WPW • Two main types of WPW are seen: Type A, where the bundle of Kent is left sided near the mitral valve. QRS is upright in V1 and V6. • In type B the accessory pathway is posterior, and the QRS is predominantly negative in V1

Slide 34:

WPW

Slide 35:

WPW Again notice the widened QRS and delta wave.

Slide 36:

WPW • Patients are prone to supraventricular arrhythmias that can conduct rapidly down the accessory pathway at very fast rates leading to ventricular fibrillation and death. This, however, occurs rarely. • Definitive treatment is ablation of the accessory pathway.

Slide 37:

PACs • Common extra beats where the atrium depolarizes spontaneously before the next sinus beat should appear. • They often have premature and abnormal looking P waves • The QRS usually looks like the other QRS complexes.

Slide 38:

PACs Notice the early impulse with the unusual P wave that precedes the QRS. The P wave will be buried in the T wave if the beat comes very early.

Slide 39:

VENTRICULAR ARRHYTHMIAS

Slide 40:

Idioventricular Rhythm • A focus in the ventricle takes over as the pacemaker of the heart This may be due to failure of pacemaker function from the SA node and AV node. • On the ECG there are wide, bizarre QRS complexes at a rate of 20-40, often associated with t-wave inversions. If this rhythm is seen in with a heart block, it is know as a ventricular escape rhythm.

Slide 41:

Idioventricular Rhythm

Slide 42:

Accelerated Idioventricular Rhythm • Accelerated idioventricular rhythm (AIVR) is a fairly common rhythm at a rate of 60-100, and often occurs in short bursts after an MI or may be seen with digoxin toxicity. • AIVR is usually transient and benign, and does not carry the same prognosis as

Slide 43:

AIVR in a patient 2 days post MI

Slide 44:

Ventricular Tachycardia • A potentially dangerous rhythm that is usually a re-entrant ventricular arrhythmia, arising from a site of abnormal ventricular tissue, often due to ischemia, fibrosis, etc. • It also can be precipitated by hypo or hyperkalemia, severe hypocalcemia, hypomagnesemia, severe illness with high catecholamine states, and congenital causes.

Slide 45:

Ventricular Tachycardia ECG findings: • Rapid, wide, bizarre looking QRS complexes at a rate usually above 120-140. • The rhythm may be regular or irregular. Sometimes p-waves that are unrelated to the QRS complexes are seen (AV dissociation), usually confirming the diagnosis of v-tach.

Slide 46:

Ventricular Tachycardia Here, a PVC landing on T wave initiates V Tach

Slide 47:

Ventricular Tachycardia P waves dissociated from QRS signifies V-tach

Slide 48:

Ventricular Tachycardia

Slide 49:

Torsades de Pointes (Twisting of the Points) • !This is a form of polymorphic ventricular tachycardia that is caused from prolongation of the QT interval (many drugs, low Mg, etc.). • !On the ECG it looks like v-tach, but the axis shifts 180 degrees, so the complexes shift from positive to negative over several beats. • !Treatment is with IV magnesium, or pacing to shorten the QT interval.

Slide 50:

Torsades de Pointes

Slide 51:

Torsades de Pointes The Axis shifts 180 degrees

Slide 52:

Ventricular Fibrillation • This is a lethal rhythm resulting from chaotic,random depolarization of the ventricle. • It is the usual cause of sudden death. • There is an undulating, disorganized rhythm without distinct QRS complexes on the ECG, which may be coarse or fine. • Treatment is immediate electrical

Slide 53:

Ventricular Fibrillation Coarse Fine

Slide 54:

Asystole • No visible electrical actvity • “Flatline” ECG • Need to be sure it is not fine v-fib.

Slide 55:

PVCs • Premature ventricular contractions are very common, and may be found in up to 40% of normal individuals. • Their prognostic importance depends on the underlying condition and presence of structural heart disease.

Slide 56:

PVCs • On the ECG they appear as early, wide, bizarre- looking complexes with a different morphology than the underlying rhythm. They typically have an abnormal repolarization pattern, often with ST segment depression and t wave inversion. • Ventricular bigeminy refers to the pattern of every other beat being a PVC; trigeminy is where every third beat is a PVC. PVCs grouped in 2s are referred to as couplets.

Slide 57:

PVCs Note the compensatory pause that occurs because the next cycle comes during the PVC or when the ventricle is refractory.

Slide 58:

Pacemaker-Ventricular The ventricular lead is in the right ventricle, and the resultant complex is wide, often with T wave inversions. Notice the spikes just preceding the QRS.

Slide 59:

Dual Chamber Pacemaker (a) (v) Note both atrial(a) and ventricular(v) pacing occur, depending on the need.