Cardiac Dysrhythmias NURS 241 Chapter 36 (p.818)

Rhythm Interpretation Questions Is the rate regular or irregular? Is the rate slow, regular, or fast? Are there ‘p’ waves? Do they all look normal and/or the same? Is there a ‘p’ wave for every QRS complex Is the PR interval normal Is the QRS complex normal Pg. 822 (Table 36-2) Interval durations Pg. 825 (Table 36-7) Dysrhythmia characteristics

Cardiac Cycle & EKG

Cardiac Cycle & EKG

Determining Heart Rate 1 mm = 0.04 sec (or each individual block) 5 mm = 0.2 sec (or between 2 dark vertical lines) Rate = 300/#5mm boxes b/w R-to-R Rate = 1500/#1mm boxes b/w R-to-R If rhythm irregular… count number of R waves in 6 seconds and multiply by 10 for an estimated rate

Before we look at abnormal… Let’s establish the normal… Sinus Rhythm! Regular rhythm Rate: Normal, 60-100 bpm P waves normal, all look same, one for every QRS Normal PR interval 0.12-0.2 sec Normal QRS interval 0.08-0.12sec

Sinus Bradycardia Regular rhythm Rate: Slow, less than 60 bpm P waves normal, all look same (kind of), one for every QRS PR & QRS intervals normal Causes: vagal stimulation, hypothermia, inferior MI, increased ICP, hypothyroid, cardiac meds (beta blockers) Tx w/ atropine ONLY if pt. symptomatic

Sinus Tachycardia Regular rhythm Rate: Fast, greater than 100 bpm P waves normal, all look same (kind of), one for every QRS PR & QRS intervals normal Causes: Fever, pain, physical activity, MI, HF, medications (epinephrine, dopamine), hypovolemia Tx: address underlying cause, PRN IV beta-blockers

Premature Atrial Contractions (PACs) Atrial ectopy (source outside SA node stimulated beat) Rhythm: Irregular d/t premature beats Rate: Varies, typically normal P waves of PACs may look different Causes: stress, fatigue, stimulants, hypoxia Tx: only if symptomatic, beta-blockers

Paroxysmal Supraventricular Tachycardia (PSVT) Regular (occas. slightly irregular) rhythm Rate: Fast, 150-220 bpm P waves often hidden in preceding T wave (if P waves visible- may have abnormal shape) PR interval typically short, QRS interval normal Causes: overexertion, stress, stimulants, dig toxicity, CAD Tx: vagal maneuvers, adenosine, beta-blockers, cardioversion

Atrial Flutter Regular rhythm typically Rate: atrial 200-350 bpm, ventricular varies No P waves, only flutter waves, sawtooth appearance Causes: CAD, HTN, MV disease, chronic lung disease Tx: beta-blockers, Ca channel blockers, cardioversion, antidysrhythmic Rx, cardiac ablation

Atrial Fibrillation Disorganized atrial electrical activity (multiple ectopic foci) Rhythm: Irregular Rate: Varies, atrial 350-600 bpm No P waves, only fib waves, normal QRS typically Causes: CAD, cardiomyopathy, HTN, HF, pericarditis, electrolyte imbalance, post-cardiac surgery Tx: Control ventricular rate (beta blockers, Ca channel blockers-diltiazem), antidysrhythmics- amiodarone, cardioversion, coumadin if CAF

Junctional Rhythm Rhythm originates from AV node either d/t SA failure or block Regular rhythm Rate: Slow, 40-60 bpm P waves either buried in QRS or abnormally close to QRS PR interval either not measurable or less than 0.08 QRS interval typically normal Tx: If junctional escape rhythm present (alternation b/w SR and Junctional), may give atropine

Accelerated Junctional Regular rhythm Rate: Normal, 61-100 bpm P waves either buried in QRS or abnormally close to QRS PR interval either not measurable or less than 0.08 QRS interval typically normal

Junctional Tachycardia Regular rhythm Rate: Fast, great than 100bpm P waves either buried in QRS or abnormally close to QRS PR interval either not measurable or less than 0.08 QRS interval typically normal Causes of junctional rhythms: CAD, HF, cardiomyopathy, electrolyte imbalance, inferior MI, digoxin Tx accel. Junct. And/or Junct. Tachy.: Digoxin stopped if cause, CA channel blockers, beta blockers

First Degree AV Block Regular Rhythm Rate: typically normal but can be faster/slower P waves for every QRS, normal in appearance, but… PR interval is prolonged, greater than 0.2 sec QRS normal Causes: MI, CAD, hyperthyroid, digoxin, beta blockers, Ca channel blockers Tx: removal of causal drug if applicable, monitor for worsening block

Second Degree Type 1 AV Block AKA Wenkebach Atrial rate regular, normal; ventricular rate irregular and slower P waves exist, but more P waves than QRS complexes PR interval gradually increases until a QRS is dropped QRS interval normal Causes: digoxin, beta blockers, CAD, may be transient post-MI (or precursor for worsening block) Tx: If symptomatic- atropine or temporary pacemaker

Second Degree Type II AV Block PR interval is prolonged but constant QRS waves are periodically dropped Atrial normal rate & rhythm, Ventricular slower and regular or irregular More P waves than QRS complexes (2:1 or 3:1) PR normal or prolonged, QRS widened Causes: CAD, anterior MI, drug toxicity Tx: Pt. needs permanent pacemaker b/c often progresses to complete heart block

Third Degree Heart Block AKA Complete Heart Block- no atrial impulses are conducted by ventricle Atrial rhythm regular, but may appear irregular d/t some hidden Ps Ventricular rhythm regular, rate slow 20-60 bpm P waves exist and “march out” evenly & QRS “march out” evenly, but… *There is no relation between the two * QRS may be widened Causes: Severe heart disease, MI, myocarditis, cardiomyopathy, meds Tx: Percutaneous or Transvenous temporary pacemaker placed until permanent pacemaker can be inserted, Rx to increase HR (epi, dopamine, atropine)

Premature Ventricular Contraction (PVC) Originate from ectopic ventricle foci Can be unifocal or multifocal Can be in couplets, or every other beat (bigeminy as above) Unable to see P waves @ PVC, QRS widened & distorted Causes: stimulants, electrolyte imbalances*, hypoxia, fever, stress, MI, HF, CAD Tx: Address causal factor, Rx (beta blockers, amiodarone, lidocaine), maybe nothing if pt. asymptomatic

Ventricular Tachycardia Monomorphic (as above) or polymorphic Ventricular rate 150-250 bpm, regular or irregular Wide, distorted QRS complexes Patient may OR may not have pulse with rhythm Causes: MI, CAD, significant electrolyte imbalances, CNS disorders, drug toxicity Tx: If pulse-IV amiodarone, lidocaine, cardioversion Tx: If PULSELESS- Defibrillation, CPR, see ACLS algorithm

Another Type of VTach Torsades de Pointes or Turning of the Points (type of polymorphic VT) Causes: long QTc Syndrome, low serum magnesium*, drug toxicity (Haldol) Tx: IV magnesium sulfate administration & Follow ACLS algorithm

Ventricular Fibrillation (Coarse) Irregular rhythm, non-measurable rate Ventricles “quivering”, no effective contraction PULSELESS Rhythm, need to shock & do CPR immediately (see ACLS algorithm) Causes: MI, HF, during cardiac catheterization, after coronary reperfusion, hypoxemia, acidosis, drug OD Tx: Follow ACLS algorithm

Ventricular Fibrillation (Fine) Same causes & Tx modalities Same as coarse VF except energy stores running out and essentially indicating worsening of situation Next progression… asystole

Pulseless Electrical Activity May see a rhythm on monitor BUT there is NO PULSE Poor Prognosis unless cause identified & treated Causes: hypovolemia, hypoxia, metabolic acidosis, hyper or hypokalemia, hypothermia, drug OD, cardiac tamponade, MI, PE, tension pneumothorax Tx: Follow ACLS algorithm

Asystole NO VENTRICULAR ACTIVITY (occas. P waves, nothing meaningful) Poor Prognosis NOT a shockable rhythm! Must keep doing CPR & giving ACLS until a shockable rhythm emerges (if it does)

Does this patient have a pulse?