ECG Cheat Sheet for Interpretation

Horizontal axis = How fast and frequently things are happening Ex: Polarization = Where is the electrical impulse going (direction of wave, up or down) and how fast (across more squares = slower) 5 little squares = 1 big square 5 big squares = 1 second Full page is usually 6 seconds Polarization = Where is the electrical impulse going (direction of wave) and how fast (more squares = slower) Vertical axis = Voltage, how strongly things are happening/ how MUCH electricity and response (Taller peaks = higher voltage) Methods to calculate rate: 1. Count how many QRS complexes present in a 6 second period (30 big squares or 3 hashmarks) x 10 = HR Ex: 6.5 QRS present x 10 = 65 HR 65 2. 300 divided by the number of large squares between R peaks (R-R interval) Ex: 5 squares = 300 / 5 = 60 HR 60 Ex: 2 squares = 300 / 2 = 150 HR 150 * or * Using 300 method, we can determine the rate and regularity. If there is the same number of squares between each pair of peaks, it is regular. If there is a different number between each pair of peaks, the heartbeat is irregular. If using small squares, > 3 small square difference = irregular, difference of less than 3 = regular Irregular: Regular: Atrial Depolarization - Denoted by the p wave followed by QRS complex. Distance between P and R waves (PR interval) should be 0.12 to 0.20 sec. (Start at P upswing count to Upswing of R wave) QRS complex - Should follow P wave. Should be less than 0.12 Normal Sinus rhythm: 60 – 100 BPM w/regular rhythm, P waves before each QRS should look almost identical, PR interval .12 - .20, QRS <.12 Sinus tachycardia rhythm: > 100 BPM w/regular rhythm, P waves before each QRS should look almost identical, PR interval .12 - .20, QRS <.12 (only difference from normal sinus is that it is too fast) Compensatory mechanism that may be caused by pain, fever, exercise, hypoxemia, dehydration, or anxiety. (Treat the cause) Sinus bradycardia rhythm: < 60 BPM w/regular rhythm, P waves before each QRS should look almost identical, PR interval .12 - .20, QRS <.12 (only difference from normal sinus is that rate is too slow) Caused by athletic heart (this is ok, no treatment), meds such as beta blockers, calcium channel blockers, digoxin, vagal stimulation Treatment = Pacemaker, atropine (first choice), or epinephrine Premature Atrial Contraction: - Denoted by irregular rhythm, an early QRS complex followed by normal sinus, present p waves that are different from each other on the early QRS complex each QRS should look almost identical, PR interval will vary on the early QRS, all others are normal .12 - .20, QRS .06 - .10 Supraventricular Tachycardia (SVT) (a re-entry loop) HR 150-250 w/regular rhythm, P waves might be different .12 - .20, QRS < . 10 unless intraventricular conduction delay exists tolerated better by younger Pts. Treatment, inform Dr, perform Vagal maneuvers, betablockers, calcium channel blockers, adenosine, digoxin, catheter ablation. Atrial Flutter Multiple P waves (fluttering), may occur after MI, PE, cardiac surgery, treatment same as above (SVT) Atrial fibrillation Irregular, no defined P wave (fibrillatory), caused by heart disease and alcohol. Treatment same as (SVT and flutter plus may need clot treatment/ anticoagulants like coumadin Junctional escape rhythm No P wave (SA node is inactive), AV junction is providing a rhythm. Caused my HD, MI, SA failure. Treatment: atropine, pacing, adrenergic agonists Heart block occurs when electrical signals from the atria of the heart don't conduct properly to the ventricles of the heart. There are three degrees of heart block. First degree heart block may cause minimal problems, however third-degree heart block can be life-threatening. Heart block may cause no symptoms, or it may cause dizziness, fainting, the feeling of skipped or irregular HR, dyspnea, fatigue, or cardiac arrest. Heart Block Types: ▪ First Degree (regular PR) ▪ Mobitz I (2nd Degree Type I, Wenckebach) (variable/irregular PR) ▪ Mobitz II (2nd Degree Type II) (regular PR) ▪ Complete Heart Block (3rd Degree) (variable/irregular PR) First degree block looks very normal except that we have a longer PR interval (>0.2, highlighted). This type of heart rhythm may be associated with a slower heart rate. Caused by MI, drugs (digoxin, Betablockers, CCBs), age, increased parasympathetic stimulation. It does not usually require treatment. Note it, but don’t call Dr at 2 AM. Second degree block Type 1 (Mobitz I) occurs when the electrical signal between the atria and ventricles is more impaired than in a firstdegree block. PR interval is inconsistent and grows longer and longer until you lose a full QRS complex. Thus, impairment results in an occasional failure to conduct an impulse, which causes a skipped beat (highlighted space shows where beat is missing). Caused by MI. Without symptoms this requires no treatment. Symptomatic patients may be managed with atropine or transvenous pacing and a cardiology consult should be obtained. Second degree Type 2 (Mobitz II) is caused by a sudden, unexpected failure to conduct an impulse. Note on the ECG, the PR interval is unchanged beat to beat, but there is a sudden failure to conduct the signal to the ventricles, resulting in a random skipped beat every so often. Type II blocks imply structural damage to the AV conduction system. This rhythm often deteriorates into complete heart block. Treatment for a Mobitz type II includes drugs and pacing STAT (temp transvenous, external via defibrillator, permanent). These patients require transvenous pacing until a permanent pacemaker is placed. Drugs used may be Alpha/Beta agonists (epinephrine/dopamine) Third degree block (Complete heart block). Total atrial/ventricular dissociation occurs when the signal between the atria and ventricles is completely blocked, and there is no communication between the two. None of the signals from the upper chambers make it to the lower chambers. On ECG, there is no relationship between P waves and QRS complexes, meaning the P waves and QRS complexes are not in a 1:1 ratio with each other. Third-degree AV block is the most severe of the AV blocks. Persons suffering third-degree AV block need emergency treatment including but not limited to a pacemaker. I have to think of this a very specific way to be able to identify this in a line up. So, you are outside a bar and a group of dudes walk out. You look at the tall guys (R peaks) because we always stare at tall men first, and you think they might by drunk, but they pretty much walk alike, on their own, and are marching along looking fine as a frizzle in a frog’s hair. But then you look at your little short guys (T, U and P (if P’s not buried)) mixed in with the group and some are alone, two might be hugging, and one just jumped on another short guy’s back and you think “Hwhat in the gallopin’ gussied up guinea hen are they doin’?!” There is no consistency or regularity, ratios are off, they are doing whatever the F they want. Because there is no communication. This was the only way I could connect all three of these EKG pictures as the same thing. Causes: Age, coronary artery disease, infection, medications, OD, surgery, or just spontaneous. Symptoms: dizziness, palpitations, fatigue, chest pain, SOB. Treatment is pacing. Paced ventricular rhythm (PVR) slim hairline marks or spikes shooting up or down indicate a pacemaker (see highlights) Bundle branch blocks Wide, weird looking QRS. Right highlights upper photo) Left side block looks like “W”s photo). No treatment required if no symptoms side looks like an M (see ( see highlights in lower Ventricular dysrhythmias: Premature Ventricular contractions (PVC) Rhythm can be regular or irregular rhythm are not usually a big deal, most people get them from time to time, so it just depends on how frequent they are. Causes: heart disease, scarring, decreased blood oxygen as with COPD, dialysis, anemia, pneumonia, decongestants, adrenaline/anxiety. Treatment for extremely symptomatic patients or those with sustained PVC: Class I and class III dysrhythmia agents, amiodarone, and/or ablation. Ventricular tachycardia Can be regular or irregular, HR >100, no P wave, bizarre QRS, beats are initiated by purkinje fibers. Treatment: defibrillator, cardioversion, or medications such as calcium channel blockers or amiodarone. If there is no pulse/ R wave, cardioversion won’t work. Torsade de pointes Ventricular Tachycardia is French for “twisting of points” and refers to when the heart’s two lower chambers or ventricles, beat faster than the upper chambers (atria), creating a spinning ECG with upward and downward points. HR 150 – 300. This can lead to sudden cardiac death. Syncope and presyncope episodes are a red flag. Treatment is Magnesium sulfate (cell wall stabilizer). MI causes elevated ST segments (STEMI) 3 zones to look for, Zone of ischemia, Zone of injury called Fireman’s helmet, Zone of infarction. Treatments: MONA (Morphine, Oxygen, Nitroglycerin, Aspirin) thrombolytics, beta blockers. Aspirin should be taken at night so its on board in the AM. Ventricular fibrillation typically follows an MI, its just kind of quivering. High mortality, time is of the essence. May be fine or coarse. Treatment is CPR and Defibrillation/shock. Causes: Hypoxia, hyper/hypokalemia, tension pneumothorax, tapenade, thrombosis.