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Adult Health Semester 2 Week 1
Nursing Care- Complex Health Problems II (11-63-375)
University of Windsor
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Adult Health Semester 2 Week 1
ECG
Arrhythmias-
Abnormal cardiac rhythms Prompt assessment of abnormal cardiac rhythm and patients response is critical
12 Lead ECG
Tells us: o Rhythm o Conduction defects o Electrolyte imbalances o Size of chambers Does not tell us: o Contractility of the myocardium SA node is normal pacemaker of the heart P wave- depolarization of atriums, SA node has initiated the rhythm (if no P wave, then not sinus rhythm) Q wave- first negative deflection R wave- first positive deflection S wave- negative deflection after R wave QRS complex (.04-) - ventricular depolarization, contraction of the ventricles T wave- ventricular repolarization, resting of ventricles QT interval (.35-)- first negative or positive deflection after the P to end of T wave PR interval (.12-)- beginning of p wave to first + or – deflection o Atrial kick only in sinus rhythm or with pacemaker Atrial repolarization is hidden in QRS Each small square is 0 seconds
ECG Paper Characteristics
6 second strip
Phases of Cardiac Action Potential of Ventricles
Phase 0- stimulus occurs sodium in, potassium out (turns into a +) Phase 1- overshoot (too positive)
Phase 2- plateau phase, calcium channels open sustains contractility of ventricles (CCB not given to HF patients) Phase 3- calcium channels close and Na and K try to go back to levels and go back to resting membrane potential Phase 4- resting phase has a negative charge (outside of cell membrane), more potassium in cells more sodium out of cells
Refractory Periods
ARP is the area where nothing can stimulate the ventricles (no other action potential) No QRS in a QRS RRP most vulnerable time of the heart (must be strong enough electrocution, pacemaker, etc. will cause life threatening arrythmia) o Corresponds with the peak of the T wave to the end of the T wave
Steps in Assessing the Cardiac Rhythm:
Step 1. Heart Rhythm
Rhythm o Regular: P-P or R-R intervals are basically identical o Irregular P-P or R-R intervals vary
Step 2. Heart Rate
If a 6 second strip count r waves and multiply by 10 If the rhythm is regular, two methods can be used to calculate the rate Count the number of large squares between two R waves and divide int 300 Count the number of small squares between two R waves and divide into 1500
Step 3. P Waves
If there are P waves, then the patient is in sinus rhythm; I there are no P waves the patient may be in Atrial Fibrillation
Step 4. PR Interval
Measure the interval from the beginning of the P wave to the beginning of the QRS complex. The normal PR interval is .12 to. 20 seconds (5 small squares). The PR interval represents atrial depolarization
Step 5. QRS Complex
Measure this complex from the beginning of the Q wave until the end of the S wave. The normal QRS complex is. to .10 seconds (2 ½ small squares). NB: remember that not all QRS complexes contain all of the QR&S waves! The QRS Complex represents ventricular depolarization
Step 6. ST Segment
ST segment: Place a ruler under the PR Interval: If the bottom part of the ST Segment line is more than one small square (1mm) below the PR interval, then the patient is having myocardial ischemia; if the bottom part of the ST segment is more than one small square (1 mm) above the PR interval, then the patient is probably having a myocardial infarction Line under p wave is isoelectric line must be in line with it (one square above or below is abnormal)
Step 7. T Wave
Check to see if the T wave is upright (normal); if the T wave is inverted (flipped)
ST elevation STEMI
o Drug of choice for Symptomatic bradycardia- atropine (sympathomimetic) Positive chronotropic Heart transplant will not respond to atropine o Temporary pacing o Dopamine/epinephrine infusion o Make a chart for treatment and why
Sinus Tachycardia
ECG Characteristics: o Rate: greater than 100/min o P Present o P waves precede every QRS o P-R ratio is 1: Causes o Exertion only normal from exercise o Anxiety o Fever o Anemia o Stimulants o Hyperthyroidism* o Pain o Drugs Treatment o Determined by underlying causes B-adrenergic blockers to reduce HR (post MI) and myocardial oxygen consumption
SVT/Narrow Complex Tachycardia
ECG characteristics: o Arrythmia originating in an ectopic pacemaker site in the atria o Involves enhance automaticity (any myocyte in the heart has the capability of initiating an action potential) of atrial tissue or conduction of the ectopic impulse o Rhythm is regular o Ventricular response is greater then 150/min and generally less then 200/min o No P waves o No PR interval o QRS complex .04-. o SA node does not go greater than 150 if over this it is coming from an ectopic foci Causes
o Unknown etiology o Emotional stress o Excessive intake of alcohol, caffeine, or tobacco o Valvular heart disease (especially rheumatic) o Coronary artery disease o Digitalis toxicity Treatment o Stable (Hemodynamically Stable) Attempt vagal maneuver Adenosine (Pharmacological Cardioversion) Stops the heart 6 sec half life To allow SA node to start If after two doses of Adenosine, the rhythm continues and the patient is stable, the MD may order a calcium channel blocker or beta-blocker Check vitals, chest pain, tachypnea, syncope hemodynamically unstable Deep suctioning will drop heart rate by stimulating carina o Unstable (hemodynamically Unstable) Synchronized cardioversion The SYNC button is pressed on the machine so that every R wave is flagged If this not done an “R on T” Phenomena may occur and the patient will go into a pulseless dysrhythmia Patient is sedated prior to the procedure
Pad Placement
Atrial Flutter
Atrial tachyarrhythmia identified by recurring, regular, sawtooth-shaped flutter waves Ectopic Foci fires 300/min but AV node stops some of the impulses May be fast, slow, regular or irregular Blood may pool in atrial appendage which can cause a clot and lead to stroke o Need to be on an anticoagulant Clinical Associations o Usually occurs with: CAD Mitral valve disorders Pulmonary embolus Chronic lung disease Cardiomyopathy Significance o Decrease EF aq o High ventricular rates with atrial flutter can decrease CO and cause serious consequences such a heart failure o Risk for stroke because of risk of thrombus formation in the atria Coumadin used for atrial flutter > 48hr Treatment o Stable Amiodarone
Ventricular Arrythmias
Ventricular arrhythmias originate in the ventricles below the branching portion of the bundle of His and include: Premature Ventricular Contractions (PVC’s), Ventricular Tachycardia (with or without a pulse), Ventricular Fibrillation. Most of these rhythms are or have the potential to be life-threatening and demand immediate recognition and treatment.
Premature Ventricular Contraction (PVC’s)
ECG Characteristics: o Rhythm: Underlying rhythm usually regular, irregular with PVC o Rate: Rate is that of underlying rhythm o P waves: None associated with PVC, however, P-waves associated with the underlying rhythm o PR interval: Not measurable o QRS for the PVC: Wide and bizarre, different from the QRS complexes of the underlying rhythm Causes o Can be common, becoming more frequent with age o Unknown etiology and can occur in healthy hearts o Anxiety o Excessive caffeine and alcohol intake o Drugs o Hypoxia o Acidosis o Electrolyte imbalance o CHF o MI o Valvular or Ischemic heart disease o Reperfusion following thrombolytic therapy and angioplasty, heart surgery or placement of leads or catheters in the ventricle Treatment o Treatment is guided by the number of PVC’s, usually more concerning if greater then 6/minute, couplets, runs of 3 or more consecutive PVC’s, R on T phenomena. Treatment is also guided by how symptomatic the patient is with the PVC’s o Reverse possible causes o Amiodarone, lidocaine, procainamide Descriptors of PVC’s o Unifocal Look the same as coming from the same ectopic focus o Multifocal Look different as coming from various ectopic foci o Patterns of PVC’s
Bigeminy every other complex is a PVC. Example: normal beat, PVC, normal beat, PVC o Trigeminy Every third complex is a PVC. Example: normal beat, normal beat, PVC, normal beat, normal beat, PVC o Couplet Two PVCs together o Triplet Three PVCs together. Also, may be called a three-beat run of ventricular tachycardia R on T phenomena
Monomorphic Ventricular Tachycardia
ECG Charcteristics o Rhythm: Regular o Rate: greater then 140/min o P waves: No p waves are associated with ventricular tachycardia. However, the SA node continues to beat independently and sinus P-waves may occasionally be seen o PR Interval: Not measurable o QRS Complex: Wide and Bizarre Causes o Usually occurs because of some underlying heart disease o Myocardial ischemia or infarction o Cardiomyopathy o Mitral valve prolapse o CHF o Digitalis toxicity o Antiarrhythmic medications o Electrolyte imbalances o Reperfusion o Mechanical stimulation of the endocardium by a wire or catheter Treatment o Pulse and is Stable: Amiodarone Lidocaine Procainamide o If rhythm converts, then start and IV maintenance drip with the same Antiarrhythmic that converted the rhythm o Pulse and Unstable: Prepare of synchronized cardioversion o Patient is Pulseless and Unresponsive: CPR Defibrillation versus Synchronized Cardioversion The machine is not in SYNC mode Before discharging the machine you still need to “Clear” everyone
Polymorphic Ventricular Tachycardia
Defibrillation Implantable Cardioverter-Defibrillation
Asystole
ECG Characteristics: o Rhythm: no discernible rhythm o Rate: no ventricular rate o Complexes: none Treatment o Start CPR o Check a second lead to confirm asystole o When IV established give epinephrine o Search for and treat possible contributing factors
Pulseless Electrical Activity
ECG Characteristics: o You have a rhythm on the monitor but no detectable pulse o Organized electrical depolarization occurs, but no synchronous shortening of myocardial fibers Causes o Same as asystole- the 6 H’s and the 5 T’s Treatment o Rapid identification and treatment of underlying reversible causes is critical for treating PEA o Initiate CPR o Epinephrine
What is going on?
You have a patient who has just had a central line inserted. The patient has been stable with a normal sinus rhythm. Twenty minutes after the line insertion, your patient becomes pulseless and unresponsive. There are no breath sounds on the right and you have a shifting of the sternum to the left. The rhythm shows the following:
AV Heart Blocks
An AV block is a disturbance in the atrioventricular conduction of the heart Normally the AV node acts as a bridge between the atria and ventricles An AV block is a failure or delay in conduction across the bridge The PR interval measures the time between the initial depolarization of the atria and the initial depolarization of the ventricles Heart blocks include: o First degree AV block (mildest form) o Second degree AV block Type I o Second degree AV block type II o Third degree AV block or complete heart block (most severe) o * you will not be asked to identify different heart blocks*
Pacemakers
Pacemaker is a battery-powered device that delivers an electrical stimulus to the myocardium resulting in contraction Reasons to pace a patient o Symptomatic bradycardia o Sinus arrest o Slow atrial fibrillation o Alternating brady and tachy arrythmia o Second degree heart block type II o Third degree heart block Function of pacemakers o Fixed pacemaker (asynchronous) Initiate impulse at a set rate regardless of the patient’s intrinsic rate o Demand pacemaker (synchronous) Designed with a sensing mechanism that inhibits discharge when the patient’s intrinsic rate is above the pacemakers set rate Types of pacemakers o Temporary- used for emergency and/or till permanent pacemaker can be implanted o Transthoracic epicardial- electrodes attach to epicardium during open heart surgery o Transvenous endocardial- pacing catheter through IJ or subclavian to RA or RV or both o Transcutaneous- pace through defibrillator pads o Permanent o Single chamber pace maker- which sense and pace either the atrium or the ventricle o Dual chamber pacemaker- which sense and the ventricle Pacemaker terms o Firing- indicates that the pacemaker has discharged. This is reflecting on the ECG tracing by a stimulus artifact (spike), followed by a “P” wave if the wire is in the atrium and followed by a wide QRS complex if the wire is in the ventricle o Capture- indicates that the atrium and/or ventricle has responded to a pacing stimulus o Sensing- the pacemaker identifies the patients intrinsic beat and does not fire. It inhibits pacing
Ventricular Pacing with Capture
Adult Health Semester 2 Week 1
Course: Nursing Care- Complex Health Problems II (11-63-375)
University: University of Windsor
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