5AB Dysrhythmia Interpretation tation and Management Review Please complete and return by:

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1 1 5AB Dysrhythmia Interpretation tation and Management Review 2014 RN Please complete and return by:

2 Overview 2 This review begins with a discussion of the physiology of cardiac conduction, and then covers the basics of how to interpret an ECG strip, and the normal components of the ECG waveform. It will then examine basic cardiac dysrhythmias, including atrial and ventricular dysrhythmias, and blocks. Learning Intentions This review will help you to: Identify basic normal ECG waveform morphology Describe the normal physiology of cardiac conduction Distinguish between basic dysrhythmias Describe the physiological consequences and treatments of basic dysrhythmias Demonstrate proper electrode placement and maintenance

3 Physiology of Cardiac 3 In an adult with a healthy heart, the heart rate is usually between beats per minute. The excitatory and electrical conduction system of the heart is responsible for the contraction and relaxation of the heart muscle. The sinoatrial node (SA node) is the pacemaker where the electrical impulse is generated. This node is located along the posterior wall of the right atrium right beneath the opening of the superior vena cava. It is crescent shaped and about 3 mm wide and 1 cm long. The impulse travels from the SA node through the internodal pathways to the atrioventricular node (AV node). The AV node is responsible for conduction of the impulse from the atria to the ventricles. The impulse is delayed slightly at this point to allow complete emptying of the atria before the ventricles contract. The impulse continues through the AV bundle and down the left and right bundle branches of the Purkinje fibers. The Purkinje fibers conduct the impulse to all parts of the ventricles causing contraction (Guyton, 1982). Abnormal heart rhythms occur for several reasons: 1. Parasympathetic Stimulation timulation: Vagal stimulation of the parasympathetic nervous system can cause a decrease in the rate at the SA node and can also decrease the excitability of the AV junction fibers. This causes the heart rate to slow and in severe cases a complete blockage of the impulse through the AV junction. 2. Sympathetic Stimulation: Stimulation of the sympathetic nervous system can also affects cardiac rhythm and conduction. It increases the rate at the SA node and increases the rate of conduction and excitability throughout the heart. It also increases the force of myocardial contraction. Subsequently, the overall workload on the heart is increased. 3. Ectopic foci: A small area of the heart can become more excitable than normal which causes abnormal heart beats called ectopy. Ectopic foci are usually caused by an irritable area in the heart. This irritability may be the result of ischemia, stimulants such as nicotine and caffeine, lack of sleep, or anxiety (Guyton, 1982). Rates of the Heart s Electrical System SA Node bpm Atrial tissue 75 bpm AV Junction bpm Ventricles bpm

4 Electrodes 4 Good Skin Prep: Clip hair if present. This allows for better contact and less painful removal of patches (Note: Avoid shaving as this may increase skin irritation under the electrode) Wash skin with soap and water Rinse then dry briskly to remove dead cells and oils Some Dos and Don ts for Electrode Application pplication: DO use all the same type of electrodes DO check the gel to make sure it is fresh and moist DO NOT use alcohol or other skin products on the skin DO NOT place electrodes over: bones, areas where there is a lot of muscle or fluid movement (i.e. abdominal ascites), irritated skin, incisions Electrode Maintenance: Replace electrodes every 24 hours or as needed Write the date of the application or change on either of the upper electrodes (black or white) Follow the steps for good skin prep and electrode application each time the electrodes are changed Change or replace electrodes as needed for: loose electrodes caused by pulling or very moist skin, complaints or evidence of skin irritation, when ECG tracing is of poor quality and is causing false alarms Lead Placement: Smoke over fire, Clouds over Grass Translation: Black over Red, White over Green Brown: In the 4thintercostal space (space between the ribs) White: Below the right clavicle and near the right shoulder Green: Below the rib cage on the right side of the abdomen Black: Below the left clavicle and near the left shoulder Red: Below the rib cage on the left side of the abdomen Important Reminders: DO make sure the V lead (brown electrode) is in the intercostal space and not over the sternum or rib

5 DO make sure the red and green electrodes are placed below the rib cage DO NOT place electrodes over pacemakers or implanted defibrillators 5 Components of an ECG Strip ECG paper is a grid where time is measured along the horizontal axis. Each small square is 1 mm in length and represents 0.04 seconds Each larger square is 5 mm in length and represents 0.2 seconds Calculating heart rate from the ECG strip: Method 1: Large Box For regular rhythms, the rate can be determined by counting the number of large boxes between two R waves and then dividing that number into 300. Method 2: Small Box To calculate the ventricular rate count the number of small boxes between two consecutive R waves and divide into To calculate the atrial rate count the number of small boxes between two consecutive s and divide into If the rhythm is irregular, give a range. Method 3: Ruler Using a commercially developed ruler place the 0 mark on a complex and the third QRS (or P for atrial rate) complex from here is the rate.

6 6 PQRSTU Summary: Indicates atrial depolarization, or contraction of the atrium Normal duration is not longer than 0.11 seconds (less than 3 small squares) Amplitude (height) is no more than 2.5 mm Smooth and rounded, no notching or peaking QRS complex Consists of the q wave, R wave and S wave Indicates ventricular depolarization or contraction of the ventricles. Normally between 0.06 to 0.10 seconds in duration The duration of a QRS caused by an impulse originating in an ectopic pacemaker in the Purkinje network or ventricular myocardium is usually greater than 0.12 sec and often 0.16 sec or greater Measured from the beginning of the QRS complex to the end of the S wave R waves are deflected positively (upward) and the Q and S waves are negative (downward)

7 T wave Indicates ventricular repolarization Rounded and slightly asymmetrical Direction of the T wave is normally the same as the QRS complex Tall, peaked T waves are commonly seen in hyperkalemia Negative T waves suggests myocardial ischemia 5mm or less in standard leads I, II, and III; 10mm or less in precordial leads V1-V6. 7 U wave Occurs after the T wave (not always seen) Rounded and symmetric Usually less than 1.5 mm in height and smaller than the preceding T wave. A U wave greater than 1.5 mm in height is generally considered abnormal ST segment Indicates early ventricular repolarization Begins with the end of the QRS complex (at the J point) and ends with the onset of the T wave Normally found on the isoelectric line; may be elevated slightly in some leads (no more than 1 mm) Normally not depressed more than 0.5 mm; ST segment depression of more than ½ mm is suggestive of myocardial ischemia; elevation of more that 1mm in limb leads and 2mm in chest leads suggests myocardial injury PR interval Indicates AV conduction time Measured from the beginning of the to the beginning of the QRS complex Duration time is 0.12 to 0.20 seconds; normally shortens as heart rate increases and lengthens as heart rate decreases Duration of greater than 0.20 sec indicates the impulse is delayed as it passes through the atria or AV node QT interval Represents total ventricular activity (from depolarization to repolarization). A prolonged QT indicates a lengthened refractory period that puts the ventricle at risk for dysrhythmias, such as torsades de pointes

8 Measured from the beginning of the QRS complex to the end of the T wave General rule: duration is less than half the preceding R-R interval Varies according to age, gender and heart rate Electrolyte disorders, medications, or congential disorders can prolong the QT interval 8 Artifact Distortion of the ECG tracing by electrical activity that is non cardiac in nature is called artifact Artifact can be caused by loose electrodes, broken ECG wires, muscle tremor, patient movement, 60 cycle interference (interference caused by improperly grounded electrical equipment or other electrical interference) Steps of Rhythm Analysis Step One: Determine the rhythm s regularity. The rhythm is said to be regular when there is a constant distance between similar waves (P-P or R-R). Generally a variation of 10% is acceptable. For example, if there are 10 small boxes in an R-R interval, an R wave could be off by 1 small box and still be considered regular. In an irregular rhythm if the variation between the shortest and longest R-R interval is less than four small boxes (0.16 sec) the rhythm is essentially regular. If the R-R intervals vary by more than 0.16 seconds the rate is irregular. A regularly irregular rhythm is where the R-R intervals are not the same and vary by more than 0.16 sec but have a repeating pattern of irregularity.

9 Step Two: Calculate the heart rate using one of the methods described earlier. The Small Box Method is the most accurate. Count the number of small boxes between R-R or P-P and divide by Step Three: Identify and examine s. One should precede every QRS complex, look similar in shape, size and position. If s are absent it indicates the rhythm originates in the AV junction or the ventricles. Step Four: Assess intervals. Measure the PR interval. Is it constant, lengthening, of normal duration? Measure the QRS intervals. Are they narrow or wide, occur regularly. Step Five: Evaluate the overall appearance of the rhythm. Determine whether there is depression or elevation of the ST segment from the isoelectric line. Evaluate the T waves to see if they are upright and of normal height. Step Six: Interpret the rhythm and evaluate its clinical significance. Specify the site the rhythm originates (sinus), the mechanism (bradycardia), and the ventricular rate. Example: sinus bradycardia. Evaluate the patient s clinical presentation to determine how they are tolerating the rate and rhythm. Nursing Interventions for Patients with Dysrhythmias Understanding the mechanisms of a particular rhythm helps to determine the potential effects on patients. Some rhythms have little or no symptoms associated with them while others can impart significant hemodynamic compromise. Signs and symptoms of hemodynamic compromise include: changes in mental status (restlessness, confusion, loss of consciousness) pulmonary congestion cold, clammy skin low blood pressure signs of shock shortness of breath chest pain congestive heart failure fall in urine output

10 If a patient has a change in their rhythm: 10 Assess the patient for signs and symptoms. This includes physical assessment, vital signs, review of lab values, patient history, etc. Assess the patient for the underlying cause and contributing factors. In the case of dysrhythmias, this would entail identifying the dysrhythmia and determining if it was causing a decrease in tissue perfusion Correct the underlying cause. This may include reduction of pain and anxiety, fluid restriction, fluid replacement, restricting activities that precipitate dysrhythmias (e.g.valsalva), or administering oxygen. Administer cardiac medications Administer cardiac medications as ordered Maintain patency of all IVs and other invasive lines Provide psychosocial support for patient and family members Promote adequate rest Maintain appropriate nutritional and fluid balances Patient Education: includes acute activities such as reporting chest pain, dyspnea or other symptoms to the RN.

11 Rhythm review 11 The various dysrhythmias you are responsible for will be reviewed in this section, but first, a review of normal sinus rhythm... Normal Sinus Rhythm (RSR) the name given to a normal heart rhythm sinus node is the pacemaker each beat is conducted normally through to the ventricles Analyze Rhythm What is the rhythm? R-R and P-P intervals are constant - rhythm is regular. What is the rate? r atrial and ventricular rates are equal; heart rate is between bpm. Is there a P Wave before each QRS? Are s upright and uniform? uniform; one in front of every QRS complex. What is the length of the PRI? measures between 0.12 and 0.20 sec; constant from beat to beat Do all QRS complexes look alike? What is the length of the QRS complex? yes; less than 0.11 sec

12 12 Sinus Dysrhythmias Sinus dysrhythmias result from problems with impulse discharge or conduction from the sinus node. The SA node remains the primary pacemaker for the heart but either discharges impulses too fast, too slow, irregularly, or the impulses are blocked. Note, sinus bradycardia at rest, sinus tachycardia with exercise, and sinus arrhythmia with breathing are considered normal response.

13 13 Sinus Bradycardia Rhythm Rate PR interval QRS P-P and R-R intervals regular less than 60 bpm positive, one precedes each QRS, same shape and size normal and constant beat to beat normal Nursing Mgmt Medical Mgmt normal variation in athletes, during sleep, or in response to a vagal maneuver abnormal with heart disease, MI, medication effects (digoxin, beta blockers, calcium channel blockers, increased intercranial pressure, sick sinus syndrome, hypothyroidism SA node if the bradycardia becomes slower than the SA node pacemaker, a junctional rhythm may occur QT may be longer than normal due to slower rate Mild bpm probably asymptomatic Marked bpm S&S of hemodynamic compromise AMI: pulm edema, syncope, ST changes, bio markers assess patient - are they symptomatic? are they stable? O2 if indicated monitor BP and heart rate IV access notify MD/NP if symptomatic treat the underlying cause if asymptomatic no treatment is necessary atropine, oxygen, transcutaneous pacing if patient is hemodynamically compromised

14 Sinus Arrhythmia 14 Rhythm Rate PR interval QRS irregular, phasic with respiration bpm but may be slower or faster positive, one precedes each QRS, same shape and size normal and constant beat to beat normal Nursing Mgmt Medical Mgmt the rate usually increases with inspiration and decreases with expiration. the non respiratory form is present in diseased hearts and sometimes confused with sinus arrest medications effects SA node and follows normal conduction pathway but fires irregularly usually asymptomatic but if bradycardic may have S&S of decreased cardiac output assess patient - are they symptomatic? are they stable? monitor notify MD/NP if symptomatic treat causes if asymptomatic no treatment is necessary if symptomatic due to bradycardia atropine may be indicated

15 Sinus Tachycardia 15 Rhythm Rate PR interval QRS P-P and R-R intervals regular bpm positive, one precedes each QRS, same shape and size normal and constant beat to beat normal Nursing Mgmt Medical Mgmt normal response to increased oxygen demands (exercise, fear, fever, HF, PE, pain, stress, MI, medications) SA node and discharges regularly rate related; may be none cardiac output, especially those with CAD chest discomfort assess patient- are they symptomatic? are they stable? O2 if indicated monitor BP and heart rate IV access treat cause if able (i.e. pain, fever, anxiety) notify MD/NP if persistent or symptomatic treat the underlying cause if asymptomatic no treatment is necessary for AMI, beta blockers given to slow HR

16 Sinus Arrest 16 Rhythm Rate PR interval QRS the basic rhythm is regular. The length of the pause is not a multiple of the sinus interval. normal but varies due to the pause those that are present are normal normal normal Nursing Mgmt Medical Mgmt may also occur with hypoxia, myocardial ischemia or infarction, hyperkalemia, medications, and increased vagal tone SA node fails to initiate electrical impulse for one or more beats may produce no symptoms may cause weakness, lightheadedness, dizziness or syncope assess patient - are they symptomatic? are they stable? oxygen if indicated IV access notify MD/NP if frequent or prolonged if episodes are transient and asymptomatic monitor IV atropine 5B temp pacing prn (if wires in situ) call code if acutely decompensating if episodes are transient and asymptomatic monitor if compromised- IV atropine episodes frequent or prolonged (>3 sec) - temporary or permanent pacing

17 Sinoatrial Block 17 Rhythm Rate PR interval QRS basic rhythm is regular*. normal or bradycardia and varies because of pause those present are normal normal and constant beat to beat normal Nursing Mgmt Medical Mgmt SA block is uncommon and usually occurs transiently may occur in healthy patients with increased vagal tone also found with CAD, inferior MI, and due to medications failure of cells in SA node to conduct impulse from pacemaker cells to surrounding atrium impulse is blocked as it exits the SA node may produce no symptoms may cause weakness, lightheadedness, dizziness or syncope assess patient - are they symptomatic? are they stable? oxygen if indicated, monitor BP and heart rate IV access if asymptomatic observe review medications 5B temp pacing prn (if wires in situ) IV atropine call code if acutely decompensating asymptomatic - observe if hemodynamic compromise is present, atropine may be indicated if episodes of sinus arrest are frequent or prolonged, temporary or permanent pacing In a type I SA block, the P-P interval shortens until one is dropped. In a type II SA block, the P-P intervals are an exact multiple of the sinus cycle, and are regular before and after the dropped.

18 Atrial Dysrhythmias 18 Atrial dysrhythmias originate from an ectopic site (a source other than the SA node) in the atria usually as a result of disorders of impulse formation or impulse conduction. Ectopic s will differ in shape from the normal sinus. An increased heart rate decreases the amount of time available for coronary artery perfusion and ventricular filling and can therefore compromise cardiac output.

19 Premature Atrial Complex 19 Rhythm Rate PR interval QRS regular with premature beats; PAC's occur early in the cycle and they usually do not have a complete compensatory pause normal but depends on underlying rhythm premature; usually have a different morphology than sinus s because they originate from an ectopic pacemaker normal, however the ectopic beats may have a different P-R interval usually normal Clinical l Features Nursing Mgmt Medical Mgmt common in both healthy and diseased hearts can also result from HF, ischemia, emotional stress, atrial enlargement, valvular heart disease, stimulants may be due to altered automaticity or reentry an irritable site in the atria fires before the next SA node impulse is due may c/o skipped beat or palpitations if they occur frequently, they may lead to more serious atrial dysrhythmias (may set off episodes of atrial fibrillation, atrial flutter or PSVT) assess patient - are they symptomatic? are they stable? monitor reduce stress reduce stimulants assess electrolytes notify MD/NP if frequency increases or patient symptomatic PACs usually do not require treatment if they are infrequent treatment includes correcting the underlying cause frequent PACs may be treated with beta blockers, calcium channel blockers and/or anti anxiety medication

20 Multi-formed Atrial Rhythm 20 Rhythm Rate PR interval QRS may be irregular as pacemaker site shifts variable depending on the site of the pacemaker; usually bpm variable in morphology; at least 3 different configurations are needed for a diagnosis P-R interval varies depending on the site of the pacemaker usually normal Nursing Mgmt Medical Mgmt may occur in normal hearts (athletes, during sleep) may also be seen in patients with heart disease and digitalis toxicity may also be a precursor to multifocal atrial tachycardia shifting of the pacemaker from the SA node to atria and/or AV junction P-R interval varies depending on the site of the pacemaker rate related; may be none assess patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn assess contributing meds (digoxin) if rate increases (becomes MAT) notify MD/NP transient rhythm that resolves on its own and there is usually no treatment required unless it is caused by digitalis then the drug should be withheld vagal maneuvers calcium channel blockers to control rate.

21 Atrial Tachycardia 21 Rhythm Rate PR interval QRS regular bpm for each QRS but differ in shape from sinus s may be shorter or longer than normal normal Nursing Mgmt Medical Mgmt stimulants infection electrolyte imbalance acute illness MI series of rapid beats from an irritable site in the atria irritable site overrides the SA node and becomes the pacemaker often confused with ST rate related; may be none S&S of decreased cardiac output assess patient - are they symptomatic? are they stable? VS, LOC, symptoms bed rest prn oxygen prn, IV access, notify MD/NP if patient symptomatic call code if decompensating treat underlying cause oxygen meds to slow rate (beta blockers, calcium channel blockers) adenosine

22 Atrial Flutter 22 Rhythm Rate PR interval QRS usually regular, but can be irregular if the AV block varies atrial bpm; ventricular conduction depends on the capability of the AV junction (usually rate of bpm) not present; usually "saw tooth" flutter waves are present. not measurable normal Nursing Mgmt Medical Mgmt usually a paroxysmal rhythm precipitated by a PAC causes include PE, hypoxia, COPD, pneumonia, cardiac surgery, cardiomyopathy, ischemic heart disease. irritable foci in atrium fires regularly at a rapid rate AV node protects ventricles from the fast rate and conducts impulses at a rate <180 bpm rate related S&S of decreased cardiac output palpitations, difficulty breathing, fatigue, chest discomfort assess patient - are they symptomatic? are they stable? monitor BP and heart rate oxygen if indicated IV access notify MD/NP if symptomatic or new onset bed rest prn call code if unstable treatment depends on the level of hemodynamic compromise, the ventricular rate, and duration of rhythm synchronized cardioversion is used when prompt rate reduction is needed digoxin and other antiarrhythmic drugs can be used

23 Atrial Fibrillation 23 Rhythm Rate PR interval QRS ventricular rhythm is usually irregularly irregular atrial rate usually between bpm. no identifiable s present; erratic, wavy baseline not measurable normal Nursing Mgmt Medical Mgmt idiopathic, HTN, HF, SSS, PE, COPD, after surgery, electrolyte imbalance, hypoglycemia, stress, hypoxia, mitral valve disease rapid firing of one or more sites in the atria, or reentry, at a rate of times/min rate related S&S of decreased cardiac output lightheadedness, palpitations, dyspnea, chest discomfort, low BP assess patient - are they symptomatic? are they stable? oxygen prn monitor BP and heart rate IV access bed rest prn notify MD/NP if new onset or symptomatic call code if unstable treatment depends on the level of hemodynamic compromise, the ventricular rate, and duration of rhythm synchronized cardioversion is used when prompt rate reduction is needed digoxin and other antiarrhythmic drugs for rate control catheter ablation

24 Supraventricular Tachycardia 24 Rhythm Rate PR interval QRS regular greater than 150 bpm not visible usually not measurable normal Nursing Mgmt Medical Mgmt CAD, HF, thyroid disease, COPD, medications, cocaine, caffeine, structural abnormalities, unknown etiology begins above the bifurcation of the bundle of His so include rhythms that begin in the SA node, atrial tissue or the AV junction rate related S&S of decreased cardiac output assess patient - are they symptomatic? are they stable? bed rest prn VS, LOC, symptoms oxygen prn, IV access notify MD/NP if patient symptomatic call code if decompensating dependent on signs and symptoms may include medications (Amiodarone, beta blocker, calcium channel blocker) ablation, cardioversion vagal maneuvers

25 Junctional Dysrhythmias 25 The inherent firing rate of the junctional pacemaker cells is 40 to 60 bpm. This rate is fast enough to sustain life with limited activity if injury or illness keeps the sinus node and atrial tissue from functioning properly. Patients with junctional rhythms often don t realize that they have a rhythm problem, especially at rates in the 50s, as it often allows people to perform normal daily activities. When the AV junction is functioning as the pacemaker, the electrical impulse produces a wave of depolarization that spreads backward (retrograde) into the atria as well as forward into the ventricles. The location of the relative to the QRS complex depends on the speed of conduction: if the electrical impulse from the AV junction depolarizes the ventricles first and then depolarizes the atria, the will be after the QRS complex if the electrical impulse from the AV junction depolarizes the atria first and then depolarizes the ventricles, the will be in front of the QRS complex if the electrical impulse from the AV junction depolarizes both the atria and ventricles simultaneously, the will be hidden in the QRS complex Retrograde stimulation of the atria is just opposite the direction of atrial depolarization when normal sinus rhythm is present and produces negative s in lead II. The PR interval is short (0.10 sec or less) and the ventricles are depolarizing normally.

26 Premature Junctional Complex 26 Rhythm Rate PR interval QRS regular with premature beats normal or accelerated. occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; may be inverted P-R interval less than 0.12 sec if s are present normal Nursing Mgmt Medical Mgmt if occasional, insignificant if frequent, junctional tachycardia may result causes include heart failure, ACS, valve disease, stimulants, digixon toxicity irritable site in AV junction fires before next SA node impulse is due impulse is conducted normally through ventricles may cause palpitations, skipped beats S&S of decreased cardiac output if frequent assess patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn review medications notify MD/NP if they become frequent or patient becomes symptomatic usually not required. treat cause(decrease contributing meds).

27 Junctional Escape Beats and Rhythm 27 Rhythm Rate QRS regular with late beats usually within normal range occur before, during or after the QRS, depending on where the pacemaker is located in the AV junction; may be inverted P-R interval less than 0.12 sec if present. normal Nursing Mgmt Medical Mgmt seen in healthy individuals during sinus bradycardia causes include ACS, hypoxia, valvular heart disease, after cardiac surgery, SA node disease, medications begins in the AV junction frequently occurs during episodes of sinus arrest (kicks in as back up pacemaker) often asymptomatic S&S of decreased cardiac output hypotension, chest discomfort altered LOC, lightheadedness SOB assess patient - are they symptomatic? are they stable? oxygen prn IV access review possible contributing medications notify MD/NP if symptomatic or new onset call code if unstable treat cause(decrease contributing meds) atropine or pacing (for symptomatic slow rate) to increase ventricular rate A junctional escape rhythm is several sequential escape beats.

28 Accelerated Junctional 28 Rhythm Rate PR interval QRS very regular bpm occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; may be inverted P-R interval usually less than 0.12 sec if present 0.11 sec or less Nursing Mgmt Medical Mgmt caused by enhanced automaticity from heart failure, ACS, valve disease, digoxin toxicity begins in the pacemaker cells of the bundle of His usually none as rate is that of regular sinus rate S&S of decreased cardiac output due to loss of atrial kick assess patient - are they symptomatic? are they stable? oxygen prn IV access notify MD/NP if symptomatic or new onset review meds check electrolyes treat cause (decrease contributing meds)

29 Junctional Tachycardia 29 Rhythm Rate PR interval QRS very regular bpm occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; may be inverted P-R interval usually less than 0.12 sec if present normal Nursing Mgmt Medical Mgmt caused by enhanced automaticity from heart failure, ACS, valve disease, digoxin toxicity begins in the pacemaker cells of the bundle of His caused by enhance automaticity S&S of decreased cardiac output racing heart severe anxiety syncope, altered LOC assess patient - are they symptomatic? are they stable? oxygen prn IV access notify MD/NP if symptomatic or new onset review contributing meds (digoxin) treat cause (decrease contributing meds) medications to control rate (beta blocker, calcium channel blocker) vagal maneuver and adenosine (to help distinguish it form other tachycardias)

30 Ventricular Dysrhythmias 30 Ventricular beats and rhythms originate below the bundle of His in a pacemaker site in either ventricle. When impulses arise in the ventricles the impulse does not enter the normal conduction pathway, but travels from cell to cell through the myocardium, depolarizing the ventricles asynchronously. Therefore, the ventricles are not stimulated simultaneously and the stimulus spreads through the ventricles in an aberrant manner, resulting in a wide QRS complex of 0.12 sec or greater. The delivery system is designed to send nearly simultaneous signals to the left and right ventricles. As a result, the two QRS complexes (one for each ventricle) occur together, overlap each other, and merge into one QRS of the expected duration, less than 0.12 seconds. However, when the depolarization begins in the ventricles, the depolarization occurs sequentially, merging to form a much wider QRS.

31 Premature Ventricular Complex 31 Rhythm Rate PR interval QRS essentially regular with premature beats; PVC's may occur in singles, couplets or triplets; or in bigeminy, trigeminy or quadrigeminy usually within normal range usually obscured by the QRS, PST or T wave of the PVC none with PVC as ectopic originates in the ventricle greater than 0.12 sec; wide and bizarre with the ST segment and the T wave in opposite direction of QRS; may be multifocal and exhibit different morphologies Nursing Mgmt Medical Mgmt occur in healthy and diseased hearts hypoxia stress, anxiety exercise electrolyte imbalance HF, MI, ACS medications irritable site in ventricles fire before next expected sinus beat often a result of enhanced automaticity compensatory pause usually follows PVC S&S of decreased cardiac output if frequent usually asymptomatic if infrequent may or may not produce a palpable pulse may c/o palpitations, racing heart, skipped beats, chest or neck discomfort assess patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn check electrolytes (hypokalemia) monitor for increasing frequency notify MD/NP if patient symptomatic or frequency increases treat underlying cause most patients with PVCs do not require treatment but if frequent and symptomatic, antiarrhythmics may be indicated

32 Ventricular Escape Beat/Rhythm 32 Ventricular escape beat Ventricular escape rhythm/idioventricular rhythm Rhythm Rate PR interval QRS essentially regular with late beats usually normal but depends on underlying rhythm; bpm for idioventricular rhythm usually absent or with retrograde conduction none as originates in the ventricles 0.12 sec or greater, wide and bizarre; T wave frequently in opposite direction of QRS complex

33 33 a protective mechanism to protect the heart from more extreme slowing may also occur as a result of acute coronary syndrome, digoxin toxicity, or metabolic imbalances impulse is generated in the ventricles when the SA node or AV junction fail to initiate an impulse, or becomes slower than the intrinsic rate of the Purkinje fibres decrease in cardiac output due to loss of atrial kick palpitations, weakness, dizziness, hypotension Nursing Mgmt assess patient - are they symptomatic? are they stable? IV access O2 if indicated IV atropine 5B patients - may initiate temp pacing if wires in situ call code, CPR if unstable Medical Mgmt treat underlying cause improve cardiac output (vasopressors) assess contributing medications For idioventricular rhythm: establish a normal rhythm transcutaneous/epicardial pacing medications (epinephrine, dopamine) if pulseless, CPR and ACLS guidelines are indicated Caution: Suppressing the ventricular rhythm is contraindicated because that rhythm protects the heart from complete standstill

34 Accelerated Idioventricular Rhythm 34 Rhythm Rate PR interval QRS essentially regular bpm usually absent or with retrograde conduction, may appear after QRS none as originates in the ventricles 0.12 sec or greater; wave frequently in opposite direction of QRS complex causes may include failure of SA node and AV junction to initiate an impulse myocardial infarction digoxin toxicity metabolic imbalances cardiomyopathy impulse originates in the ventricles as both the SA node and AV tissue fail to initiate an impulse intrinsic firing of the ventricles S&S of decreased cardiac output due to slow rate and lack of atrial kick pale, cool skin weakness dizziness, hypotension altered LOC Nursing Mgmt assess patient - are they symptomatic? are they stable? oxygen prn IV access review medications notify MD/NP call code if patient decompensates Medical Mgmt treat underlying cause improve cardiac output (vasopressors) assess contributing medications establish a normal rhythm transcutaneous/epicardial pacing if pulseless, CPR and ACLS guidelines are indicated Caution: Suppressing the ventricular rhythm is contraindicated because that rhythm protects the heart from complete standstill

35 Ventricular Tachycardia Monomorphic VT Monomorphic VT : Ventricular tachycardia is called monomorphic VT when the QRS complexes are the same shape and amplitude 35 Rhythm Rate PR interval QRS three or more ventricular beats in a row; essentially regular bpm may be present or absent; if present they are unrelated to the QRS complexes none greater than 0.12 sec; wide and bizarre; difficult to differentiate between QRS and T wave common causes are ACS, cardiomyopathy, valvular heart disease, cocaine abuse, electrolyte imbalance can quickly deteriorate into ventricular fibrillation drugs or congenital disease that lengthens the QT interval impulse originates in the ventricles less than 30 seconds it is called non- sustained VT greater than 30 seconds it is sustained VT S&S of decreased cardiac output syncope Nursing Mgmt assess your patient - are they symptomatic? are they stable? if patient has pulse: oxygen, bed rest, IV access, notify MD STAT, monitor closely if patient is pulseless or unstable: call code, ABCs, CPR, IV access Medical Mgmt treat underlying cause (IV magnesium or potassium to correct imbalances) stable symptomatic patients are treated with oxygen and antiarrhythmics to suppress the rhythm unstable patients are treated with oxygen and synchronized cardioversion CPR and defibrillation are used to treat the pulseless patient

36 36 Polymorphic VT: When the QRS complexes vary in shape and amplitude from beat to beat the rhythm is polymorphic VT. Polymorphic VT that occurs in the presence of a long QT interval is called Torsades de Pointes. The hallmark of this rhythm is the upward and downward deflection of the QRS complexes around the baseline. The term torsades de pointes means "twisting about the points." Rhythm Rate PR interval QRS may be regular or irregular bpm absent none greater than 0.12 sec; gradual alteration in amplitude and direction of the QRS complexes anything that decreases oxygen delivery to the ventricles bradyarrhthymias, 3 degree block excessive antiarrhythmics, haldol electrolyte imbalance (hypokalemia, hypomagnesemia) congenital LQTS liquid protein diets CNS disorders impulse originates in the ventricles less than 30 seconds it is called non- sustained VT greater than 30 seconds it is sustained VT S&S of decreased cardiac output due to fast rate causing decrease filling time, and loss of atrial kick syncope, hypotension, altered mental status, shock, chest pain, SOB, pulmonary congestion Nursing Mgmt call code, ABCs, CPR ensure IV access notify MRP Medical Mgmt ACLS guidelines, defibrillate treat precipitating causes meds, electrolytes ICD for prophylaxis Amiodarone is NOT used as it can prolong the QT further

37 Ventricular Fibrillation 37 Rhythm Rate PR interval QRS chaotic electrical activity with no pattern or regularity unattainable not discernible not discernible not discernible Nursing Mgmt Medical Mgmt causes include increased SNS activity vagal stimulation electrolyte imbalance medications hypertrophy ACS HF arrhythmias MI chaotic rhythm originating in the ventricles no organized depolarization so no effective ventricular contraction coarse VF wave 3 mm or higher fine VF wave less than 3 mm in amplitude VT usually deteriorates to VF within 3 minutes no cardiac output, no peripheral pulses, no BP, loss of consciousness death imminent if untreated coarse VF indicates a more recent onset and more likely to be reversed by defibrillation assess patient call code, ABC, CPR IV access CPR and defibrillation ACLS protocols (ephinephrine, vasopressin, Amiodarone, atropine)

38 Asystole/Ventricular Standstill 38 Rhythm Rate PR interval QRS ventricular not discernible no ventricular activity but atrial activity may be seen may be seen, but there is no ventricular response not measurable none Nursing Mgmt Medical Mgmt may occur temporarily following the termination of atrial, AV junctional or ventricular tachycardias same causes as those of cardiac arrest absence of ventricular activity some atrial activity may be present S&S of absent cardiac output pulseless assess patient call code, ABC, CPR IV access check two leads to ensure it is asystole and not fine VF or leads off treat underlying cause CPR and defibrillation if a shockable rhythm resumes ACLS protocols medications

39 Atrioventricular Blocks 39 The term heart block is used to describe arrhythmias in which there is delayed or failed conduction of impulses through the AV node into the ventricles. The PR interval is primarily a measure of conduction between the initial stimulation of the atria and the initial stimulation of the ventricles (normally 0.12 to 0.20 sec). When the PR interval is too long, the signal is 'blocked' in the AV node. It may just be delayed longer than usual, or the AV node may be letting some signals through and holding others back, or all the signals may be blocked completely. AV blocks can occur at the level of the AV node, the bundle of His, or the bundle branches. When located at the AV node of bundle of His, the QRS complexes will be normal duration. When located in the bundle branches, the QRS complex will be wide. The clinical significance of an AV block depends on the degree of block, the ventricular rate, and the patient response.

40 First Degree AV Block 40 Rhythm Rate PR interval QRS regular usually within normal range normal impulse originates in the SA node but has prolonged conduction in the AV junction; P-R interval is greater than 0.20 sec normal Nursing Mgmt Medical Mgmt occurs in both healthy and diseased hearts may be due to inferior MI, medications hyperkalemia, increased vagal tone, and injury to the AV node or junction. SA node fires impulse and the impulse is conducted normally but is delayed at the level of the AV node often asymptomatic unless marked first degree assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms monitor for progression notify MD/NP if PRI continues to lengthen review contributing meds treat underlying cause observe for progression to a more advanced AV block if result of AMI, monitor closely First degree AV block is not a dysrhythmia itself but rather a condition describing the prolonged PR interval. Analysis should include a description of the underlying rhythm.

41 Second Degree AV Block Type I 41 Rhythm Rate PR interval QRS atrial regular, ventricular irregular atrial rate is greater than the ventricular rate normal; constant P-P interval; some s not followed by a QRS complex the PR interval is progressively longer until one appears without a QRS complex normal Nursing Mgmt Medical Mgmt occurs in both healthy and diseased hearts may be due to inferior MI, medications hyperkalemia, increased vagal tone, and injury to the AV node or junction. often caused by right coronary artery occlusions as it supplies the AV node occurs in the AV node above the Bundle of His and is caused by a conduction delay within the AV node often asymptomatic as ventricular rate is near normal S&S of decreased cardiac output assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn IV access review medications notify MD/NP if patient symptomatic or new onset atropine IV 5B temp pacing prn in PW in situ treat underlying cause if rate slow atropine or pacing may be indicated if result of AMI, monitor closely

42 Second Degree AV Block Type II 42 Rhythm Rate PR interval QRS atrial regular, ventricular irregular atrial rate is greater than ventricular rate; ventricular rate is often slow normal; some s not followed by a QRS complex P-R interval may be normal or prolonged, but it is constant until one P wave is not conducted to the ventricles usually 0.10 sec or greater; periodically absent after Nursing Mgmt Medical Mgmt causes include acute myocarditis, acute anterior MI (left coronary artery supplies bundle branches) block usually occurs below the bundle of His or at the level of the bundle branches may progress into a third degree block S&S of decreased cardiac output due to decreased ventricular rate assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn; IV access call code if unstable review medications notify MD/NP ASAP 5B temp pacing prn if PW in situ treat underlying cause assess contributing medications if rate slow pacing may be indicated permanent pacemaker This is more serious than the Type I block. Atropine should be avoided as it will not improve the block but will increase the rate of SA node discharge which could trigger a situation where even fewer impulses are conducted through to the ventricles.

43 Third Degree or Complete AV Block 43 Rhythm Rate PR interval QRS atrial regular, ventricular regular but no relationship between the rhythms atrial rate is usually normal; ventricular rate is determined by origin of the escape rhythm normal with constant P-P intervals, but not "married" to the QRS complexes none as atrial and ventricular activities are unrelated due to the complete blocking of the atrial impulses to the ventricles may be normal or widened depending on where the escape pacemaker is located in the conduction system Nursing Mgmt Medical Mgmt associated with anterior and inferior MIs digitalis toxicity acute infection degeneration of the conductive tissue. impulses generated by SA node are blocked before reaching the ventricles atria and ventricles beat independently of one another secondary pacemaker stimulates the ventricles S&S of decreased cardiac output due to decreased ventricular rate assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms oxygen prn; IV access 5B temp pacing prn if PW in situ call code if unstable notify MD/NP ASAP treat underlying cause external pacing atropine (depending on escape pacemaker) permanent pacing for chronic complete heart block.

44 Paced Rhythms 44 Some indications for pacing include: sinus bradycardia sinus arrest sinus exit block atrial flutter or fib sick sinus syndrome chronotropic incompetence (SA node incapable of increasing rate in response to activity) 2nd degree AV block type II 3rd degree AV block If a pacemaker senses a, the pacemaker is inhibited from firing an electrical stimulus. If the pacemaker does not sense a, the pacemaker sends an electrical stimulus to the atrium. Stimulation of the atrium produces a pacemaker spike followed by a. The pacemaker is programmed to wait simulating an electronic PR interval (called the AV interval). The same thing happens for the ventricles if it is a dual chamber pacemaker. Dual chamber pacemakers stimulate the atria and ventricles in sequence mimicking normal heart physiology and thus preserving atrial kick. Because the pacemaker lead doesn t lie in the sinus node or the AV node, the s and QRS complexes will vary from normal. Usually the wire is embedded at the bottom of the ventricle (far from the AV node) so QRS complexes are wide and bizarre. Fusion beats occur when a pacing stimulus and an intrinsic beat partly depolarize the ventricles. A pseudo-fusion beat occurs when a pacemaker spike precedes an intrinsic QRS complex but doesn t change it. The pacemaker spike location gives the false impression that the spike influenced the QRS. Fusion beats

45 Analyzing Pacemaker Function 45 Step One: Identify the intrinsic rate and rhythm: Are s present? At what rate? Are QRS complexes present? At what rate? Step Two: Measure the paced interval: Measure the paced interval by measuring the distance between two consecutive paced beats like you would measure R-R except place calipers on pacing spikes. Ex. spike to spike is 19 small boxes = paced interval of 79 Step Three: Analyze the rhythm strip: Determine rate and regularity of paced activity. Analyze the strip for failure to capture, failure to sense, oversensing or failure to pace AV sequential pacemaker or 100% AV paced 100% Atrial paced 100% Ventricular paced

46 Pacemaker Complications (applies to temporary and permanent pacemakers) 46 Failure to Pace Occurs when the pacemaker fails to deliver an electrical stimulus or the correct number of electrical stimuli per minute. Failure to pace is recognized by a lack of pacemaker spikes and a return to the rhythm that indicated the need for a pacemaker. Caused by: battery depletion disconnection in the system lead fracture electromagnetic interference pacemaker turned off or programmed incorrectly pacemaker does not discharge a stimulus to the myocardium lack of a pacing spike where expected if the pacemaker doesn't sense an intrinsic beat after 1000 ms (this will vary depending on the base rate) after the last beat, it should fire. hypotension bradycardia syncope chest pain return of symptoms associated with rhythm for which pacemaker was implanted

47 Treatment Nursing Management assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms IV access notify MD/NP if patient on temp epicardial pacing check battery, ensure unit is turned on, replace pulse generator, remove any electromagnetic interference call code if unstable, CPR 47 Medical Management adjust pacemaker settings surgery to replace lead or device IV atropine ACLS guidelines if pulseless or decompensated Failure to Capture Is the inability of the pacemaker stimulus to depolarize the myocardium. The pacemaker fires but does not stimulate the ventricle/atria enough to cause contraction. On the strip you will see a pacing spike with no corresponding or QRS complex. Causes may include battery failure, lead fracture, pacing lead displacement, edema or scar tissue formation at electrode tip, output energy set too low. Caused by: battery failure scar tissue or edema at electrode tip lead fracture or displacement energy output too low

48 medications electrolyte imbalance (alters ability of heart to respond to stimulus) 48 pacemaker discharges a stimulus to the myocardium but the myocardium does not depolarize pacing spike not followed by a or QRS complex hypotension bradycardia syncope fatigue Treatment Nursing Management assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms reposition patient notify MD/NP if patient on temp epicardial pacing check battery, ensure unit is turned on, replace pulse generator, check all connections call code if unstable, CPR Medical Management adjust pacemaker settings (increase output) surgery to replace lead or device ACLS guidelines if pulseless or decompensated Failure to Sense Undersensing Occurs when the pacemaker fails to recognize spontaneous myocardial depolarization. This is recognized by the generation of unnecessary pacing spikes (follow too closely behind the patient s QRS complexes, occur earlier than the programmed escape interval). Causes include battery failure, lead fracture, pacing lead displacement, edema or scar tissue formation at electrode tip, decreased or QRS voltage, circuitry dysfunction, increased sensing threshold, myocardial perforation.

49 49 Caused by: battery failure scar tissue or edema at electrode tip lead fracture or displacement generator sensitivity too low circuitry dysfunction myocardial perforation medications electrolyte imbalance pacemaker does not recognize myocardial activity and fires earlier than it should pacing spike not followed by a or QRS complex, generally earlier than it should can occur with or without capture c/o skipped beats or palpitations risk of pacing spike falling on the T wave causing R-on-T Treatment Nursing Management assess your patient - are they symptomatic? are they stable? VS, LOC, symptoms reposition patient notify MD/NP if patient on temp epicardial pacing check battery, ensure unit is turned on, replace pulse generator, check all connections

50 Medical Management adjust pacemaker settings (increase sensitivity) pace in asynchronous (fixed) mode until problem fixed x-ray to determine lead placement surgery to replace lead or device 50 Failure to Sense Oversensing Results when there is inappropriate sensing of extraneous electrical signals (skeletal muscle activity, electrical interference). These electrical signals are interpreted by the pacemaker as intrinsic activity and as a result the pacemaker does not fire. It is recognized by absent pacemaker spikes and ventricular asystole. Caused by: battery failure device programmed incorrectly pacemaker is too sensitive and is sensing the wrong signals causing the pacemaker to reset inappropriately increasing the amount of time before the next discharge paced beat occurring later than it should can be hard to identify unless the minimum heart rate setting is known pace