Presentation on theme: "ECG Monitoring – Reference Guide"— Presentation transcript:
1 ECG Monitoring – Reference Guide Cardiac Conduction PathwayThe ECG TracingLabel ECG tracing w/P,Q,R, S, T and ULabel SA node, AV node, bundle of His, bundle branches and Purkinje fibersSA node= beats/minAV node= beats/minBundle of His= beats/minPurkinje fibers= beats/minNormal measurements:PR Interval: – 0.20 sec.QRS complex: less than 0.12 sec.QT interval: less than ½ the distance between two consecutive R waveslabel PR Inteval, QRS complex, ST segment and QT intervalRepresentation of cardiac activity on the ECG:P wave = atrial depolarizationQRS complex= ventricular depolarizationST segment = early repolarization of the ventriclesT wave = later stages of ventricular repolarization.
2 ECG Monitoring – Guide to Leads View of the heart provided by each lead:264AreaLeadLateralI, AVL (high lateral)V5, V6 (low lateral)Inferior WallII, III, AVF.Anterior WallV1-V4/ V2-V4SeptumV1, V2.American Heart Association’s standard color coding for ECG leadsLocationInscriptionColorRight ArmRAWhiteLeft ArmLABlackRight LegRLGreenLeft LegLLRedChestV1BrownLead placement for 5 lead ECGsLead placement mnemonic:White is right.Snow over trees (white over green).Smoke over fire (black over red).Chocolate (brown) is close to the heart.
3 ECG Monitoring – 5 Step Analysis Step 1: Assess the regularity of the rhythmAre the P waves (for atrial rhythm) or the R waves (for ventricular rhythm) consistently equidistant from each other?If there is a variation of more than 3 small boxes (0.12 seconds), the rhythm is considered irregular.The Square Counting, or Sequence, MethodThe square counting method can be used for regular heart rhythms. First, find an R wave that falls on a thick line. The next thick lines will be counted as follows: 300, 150, 100, 75, 60, 50, 43, 37. Stop the sequence at the next R wave. If the second R wave falls between two thick lines, use the mean of the two numbers (for example, if the R wave falls between 150 and 100, the rate would be 125)Step 2: Calculating the heart rateThe Six-Second MethodThis method can be used to easily measure the heart rate in non-regular rhythms. To calculate the ventricular rate, simply count the number of QRS complexes in a 6 second strip and multiply by 10. To calculate the atrial rate, count the P waves instead of the QRS complexes.The Small Box MethodCount the small boxes between two sequential R waves (for the ventricular rate) or two sequential P waves (for the atrial rate). Divide this number into 1500 to obtain the rate.The Large Box MethodFor this method, count the number of large boxes between two sequentialR or P waves. Divide this number into 300 to obtain the rate.
4 ECG Monitoring – 5 Step Analysis 3rd Step: Assessment of the P wavesThe P wave represents atrial depolarization.An absent P wave indicates that the electrical impulse is being generated from somewhere other than the SA node.An inverted P wave can be seen with ectopic atrial and junctional rhythms.Peaked P waves may be seen with right atrial enlargement, usually due to pulmonary hypertensionNotched P waves can be seen with left atrial enlargement, usually due to mitral stenosis. (#2b)Variable P waves are indicative of multifocal atrial rhythms (meaning multiple sites within the atrium or AV junction are acting as ectopic pacemakers).4th Step: Assessment of the PR intervalThe PR interval reflects the total time it takes for the electrical impulse to travel from the SA node through the AV node into the ventricles. A shortened PR interval (> 0.12 seconds) can indicate a junctional rhythm where the impulse originates in the AV junction, or an abnormal conduction pathway.A prolonged PR interval indicates that the impulse is being delayed before entering the ventricles. This is called first degree block and can be caused by myocarditis, acute myocardial infarction, hyperkalemia, medication effects, AV septal defects and enhanced vagal tone.A variable PR interval can indicate a wandering atrial pacemaker, Wenckebach rhythm (2nd degree Mobitz Type I), 3rd degree (complete ) AV block.Additional Assessments: The T wave & the QT intervalThe T wave represents ventricular repolarization. It usually deflects upright in all leads except aVR and V1. Assess the T wave for abnormalities in shape or consistency and for inversion in leads where it normally is upright. T wave abnormalities may be seen with myocardial ischemia or infarction, bundle branch blocks, pulmonary embolism, electrolyte imbalances and ventricular hypertrophy, among other conditions.The QT interval represents the total time for ventricular depolarization and repolarization. Abnormalities in the QT interval can indicate risk for serious ventricular arrhythmias. Prolonged QT intervals can also be caused by medication effects, hypocalcemia, myocarditis and CNS lesions.5th Step: Assessment of the QRS ComplexThe fifth step is to assess the QRS complex. The QRS complex represents ventricular depolarization.As with the PR interval, the QRS complex needs to be assessed for both duration (width) and consistency.The QRS can be classified as narrow (<0.10 sec) or wide (>0.12 sec). An abnormally wide QRS complex can indicate a delay or abnormality in conduction through the ventricle. Causes of wide QRS complexes can include bundle branch blocks, Wolff-Parkinson White syndrome, hyperkalemia, medication effects, and ventricular tachycardia, fibrillation or ectopic beats.
5 Show strips from module ECG MonitoringArrhythmia ReviewSinus RhythmsNormal Sinus RhythmRate: beats per minute (BPM)Rhythm: RegularP waves: upright, normal shape, consistent, one before each QRS complexPR interval: – 0.20 seconds (normal)QRS: seconds or lessSinus BradycardiaShow strips from moduleRate less than 60 BPMCan result in decreased cardiac outputCauses : medication effects (calcium channel blockers, digoxin, beta blockers), increased vagal tonesinus node disease, hypothyroidism, hypothermia, ischemia, increased intracranial pressureTreatments: atropine (drug of choice), epinephrine or dopamine, transcutaneous of tranvenous pacingSinus TachycardiaRate usually bpmCauses: increased activity, fever, anxiety/fear, pain, infection, hypoxia, acute MI, hypovolemia,medication effects (epinephrine, atropine), stimulants (caffeine, nicotine, or cocaine), CHFTreatment: Treat the underlying cause.Sinus ArrhythmiaRate usually bpm but may be faster or slowerRhythm is irregular (shortened R-R intervals during inspiration, lengthened during expiration)There is not usually any treatment required for sinus arrhythmia.. If significant sinus brady-dysrhythmia occurs and patient is symptomatic, treat for sinus bradycardia.
6 Sinus Rhythms (continued) ECG MonitoringArrhythmia ReviewSinus Rhythms (continued)Sinoatrial BlockRate is usually normal but will decrease with pausesRhythm is irregularCauses: SA node disease, acute MI, medication effects (digoxin, quinidine, procainamide), CAD,myocarditis, CHF, increased vagal tone or stimulation.Treatment: treatment is the same for symptomatic bradycardia, if present.Sinus Pause/ ArrestCauses: SA node disease, acute MI, medication effects (digoxin, quinidine, procainamide), myocarditis, hyperkalemia, increased vagal tone or stimulation.Atrial RhythmsPremature Atrial Contractions (PACs)Rate is variable, depending on underlying rhythmRhythm will be irregular at point of PACsPremature P waves will be different than sinus P waves , but vary depending on siteCauses : hypokalemia, hypomagnesemia, anxiety, stimulants (caffeine, tobacco or alcohol),digitalis toxicity, and myocardial ischemia or injury.Treatment: not usually required if PACs are infrequent; treat underlying causeEctopic Atrial RhythmsRate is less than 100 bpmRegular rhythmP waves are different than sinus P waves , but will depending on site; may be invertedCauses : same as PACs.Treatment: not usually required.
7 Atrial Rhythms (continued) ECG MonitoringArrhythmia ReviewAtrial Rhythms (continued)Wandering Atrial PacemakerRate is less than 100 bpmIrregular rhythmAt least three different morphologies of P waves (all vary from sinus P waves)Causes: digitalis toxicity, acute rheumatic fever, asthma, COPD, SA node disease, atrial hypertrophy and acute MI.Treatment: does not usually require treatment.Multifocal atrial tachycardiaRate is greater than 100 bpmCauses: COPD, CHF, and hypoxia.Treatment: treat the underlying disorder.Atrial FlutterAtrial rate is bpm; ventricular rate is variable.Saw-toothed flutter waves (no regular P waves)Causes: stimulants (alcohol, nicotine, etc.), stress, fatigue, electrolyte imbalances, acute MI, ischemic heart disease, valvular disease, pulmonary embolism, digitalis or quinidine toxicity. It can also occur following open-heart surgery.Treatment: may include: cardioversion, calcium-channel blockers, beta-blockers, digoxin, warfarin (to prevent emboli)Atrial FibrillationAtrial rate is usually > bpm; ventricular rate is variableFibrillatory waves (no regular P waves)Causes: stimulants (alcohol, nicotine, etc.), stress, fatigue, electrolyte imbalances, acute MI, open- heart surgery, ischemic heart disease, valvular disease, and hypertension.Treatments : cardioversion, calcium-channel blockers, beta-blockers, digoxin, warfarin (to prevent emboli)Atrioventricular Nodal Reentrant Tachycardia (AVNRT)Rate is bpmP waves may be hidden in QRS or may appear a pseudo S or R waveIn AVNRT, reentry is due to the presence of both a fast and slow pathway within the AV node that can allow the electrical impulse to reverse direction and generate another heartbeat.Treatments: Vagal maneuvers are the initial treatment for stable AVNRT.If vagal maneuvers are unsuccessful, adenosine may be administered.
8 Junctional Arrhythmias ECG MonitoringArrhythmia ReviewJunctional ArrhythmiasPremature Junctional ComplexesRate depends on underlying rhythmRegular rhythm with premature beatsP waves may be before, after or hidden in QRS; if visible, inverted in leads II, III and aVF.Causes: stimulants (caffeine, tobacco, alcohol), electrolyte imbalance, heart disease, ischemia or MI, hypoxia, digitalis toxicity and sinus node dysfunction.Treatments: no treatment is usually necessary; treat the underlying cause.Junctional Escape Beats & RhythmsJunctional escape rhythm is comprised of three or more junctional escape beats in a row.Rate is bpmP waves may be before, after or hidden in QRS;if visible, inverted in leads II, III and aVF.Causes: heart disease, acute MI, hypoxia, sinus node dysfunction, cardiac surgery and with certain medications (digitalis toxicity, beta-blockers, calcium-channel blockers).Treatment: if infrequent, treatment may not be necessary. If patient is symptomatic, may include atropine, pacing, or digibind (if related to digitalis toxicity).Accelerated Junctional Rhythms & Junctional TachycardiaRate is for accelerated junctional rhythm; for junctional tachycardiaP waves may be before, after or hidden in QRS;Causes: electrolyte imbalances, digitalis toxicity, ischemia, MI and myocarditis.Treatment: depends on severity of symptoms; may include vagal maneuvers, adenosine, digibind (if related to digitalis toxicity), antiarrhythmics, pacing or ablation therapy.
9 ECG Monitoring Arrhythmia Review Ventricular Rhythms Premature Ventricular Complexes (PVCs)*Frequent PVCs (more than 6 per minute) can be life threatening.Rate depends on underlying rhythmRegular rhythm with premature beatsNo P waves with PVCWide, abnormal QRS ; T wave is usually in opposite direction of QRS complex.Causes: stimulants (caffeine, nicotine, alcohol), stress, and fatigue, ischemia, MI,CHF, electrolyte imbalance, acid-base imbalance, digitalis toxicity, and medication effects (sympathomimetics, beta-agonists, tricyclic antidepressants).Treatments: based on the cause and the patient’s symptoms.Idioventricular rhythms (IVR)Idioventricular rhythms are composed of 3 or more continuous ventricular escape beats.Ventricular rate is bpm (atrial rate not discernible)No P wavesCauses: electrolyte imbalances, digitalis toxicity, myocardial ischemia or injury, and cardiomyopathy.Treatment: increase heart rate, may require transcutaneous pacing, atropineAccelerated Idioventricular Rhythm (AIVR)Ventricular rate is bpm (atrial rate not discernible)No p wavesWide, abnormal QRS complex; T wave is usually in opposite direction of QRS complex.Causes: digitalis toxicity, MI, myocardial ischemia or injury, and cardiomyopathy.Treatment: if unstable, cardioversion or pacing may be needed.
10 Ventricular Rhythms (continued) ECG MonitoringArrhythmia ReviewVentricular Rhythms (continued)Ventricular Tachycardia*Life threatening arrhythmiaVentricular rate bpm (atrial rate not discernible)P waves may or may not be present; not associated with QRS complexWide, abnormal QRS complexCauses : electrolyte imbalance, acid-base imbalance, myocardial ischemia or infarction, drug toxicity (digitalis, other antiarrhythmics), cardiomyopathy, infection (myocarditis, Chagas disease), CNS stimulants (cocaine, amphetamines)Treatment: If the patient is symptomatic and has palpable pulses, cardioversion is the treatment of choice. If the patient does not have palpable pulses, immediate defibrillation is required.Torsades de pointesVentricular rate bpm (atrial rate not discernible)No P wavesChanges in QRS shape, amplitude (height) and widthCauses: conditions associated with prolonged QT interval , including medications (quinidine and procainamide, among others) and electrolyte imbalances (hypokalemia, hypomagnesia, hypocalcemia).Treatment : address the cause of the prolonged QT interval. Unstable patients should be treated with defibrillation.Ventricular fibrillationNo discernible rateChaotic, rapid, irregular rhythmNo discernible P waves or QRS complexesCauses: myocardial ischemia or infarction, electrolyte imbalance, cardiomyopathy, hypoxia, congenital conditions, electrocution, untreated ventricular tachycardia, R-on-T PVCs.Treatment: Unless advanced life support is started immediately, ventricular fibrillation is a fatal rhythm. VF requires defibrillation as soon as possible. Vasopressors (epinephrine, vasopressin) and antiarrhythmics (amiodarone) may also be used – follow current ACLS protocol.
11 Atrioventricular Blocks ECG MonitoringArrhythmia ReviewAtrioventricular BlocksFirst Degree Atrioventricular (AV) BlockPR interval >0.20 seconds Causes: acute MI,medication effects (digitalis, calcium channel blockers, beta-blockers, among others), electrolyte imbalances, myocarditis, AV node diseaseTreatments: usually no treatment needed for first-degree AV block.Second Degree Atrioventricular (AV) Block, Mobitz Type 1PR interval lengthens after each P wave until QRS is eventually dropped, then cycle starts againCauses: acute MI,medication effects (digitalis, calcium channel blockers, beta-blockers, among others), electrolyte imbalances, myocarditis, AV node diseaseTreatments: usually no treatment needed.Second-Degree Atrioventricular (AV) block, Mobitz Type IIImpulses intermittently blocked resulting in dropped QRS complexesP waves occur at consistent intervalsCauses: anteroseptal MI, structural heart disease ,cardiac surgery, medication effects , infiltrative conditions , inflammatory conditions , autoimmune conditions , hyperkalemiaTreatment: temporary pacing until a permanent pacemaker can be placed.Mobitz type II is a more serious condition than type I and can rapidly progress to third-degree heart block.Third-degree Atrioventricular (AV) blockAtrial impulse are not conducted to the ventricles. Secondary pacemaker in the AV node or below pace s the ventricles.No correlation between P waves and QRS complexes.QRS will be narrow if secondary pacemaker is junctional, wide if it is ventricular.Causes: same as second-degree AV blockTreatment: most patients will require placement of a permanent pacemaker.
12 Pulseless Electrical Activity ECG MonitoringArrhythmia ReviewPulseless Electrical ActivityPulseless electrical activity (PEA) is not a specific arrhythmia, but occurs when an organized rhythm is seen on the ECG tracing but ventricular contraction does not occur and, therefore, the patient is pulseless.Show strip from modulePulseless electrical activity can present as various rhythms on the ECG tracing, including sinus rhythm, bradycardias and tachycardia.PacemakersPacemakers can pace either the atria or the ventricles (single chamber pacemakers) or both (dual chamber pacemakers).In atrial pacing, a spike will be seen prior to the P wave.In ventricular pacing, a spike will be seen before the QRS complex.Spikes before the P wave and QRS complex will be present when the patient has a dual chamber pacemaker.Show pacemaker strips from modulePacemaker Problems Notable on the ECGFailure to paceAbsence of pacemaker spikes when the patient’s heart rate is below the pacemaker rate.Failure to capturePacemaker spikes will be seen on the ECG but they will not be followed by a P wave (in atrial pacing) or a QRS complex (in ventricular pacing).Failure to senseThe pacemaker spike will be seen in an inappropriate place on the ECG (for example, after or near a QRS complex in ventricular pacing).