telemetry med surg exam 3 2022 with complete solutions

sinus node - ANSWER The intrinsic pacemaker. Cell membrane "leakiness" causes spontaneous depolarization at a rate of 60-100 times a minute. AV node - ANSWER Acts like a resistor to slow the impulse allowing time for the atria to completely contract before initiating ventricular contraction. Back up pacemaker if SA fails, pacing at a rate of 40-60 times a minute. Bundle of his - ANSWER "Cable" that passes through the fibrous sheath separating atria from ventricles. Divides into the bundle branches. Bundle branches - ANSWER "Wires" that run down the septum and into the ventricles. There are two left bundle branches and one right. Purkinje - ANSWER Terminal fibers branches from the bundles, distributing the impulse throughout the ventricles. Intranodal pathways - ANSWER "Wiring" that allows rapid impulse movement around the atria to coordinate simultaneous atria contraction Impulse vectors - ANSWER SA node Atria AV node The depolarization wave in the ventricles also travel in specific directions forming vectors. Because the left ventricle has a bigger muscle mass, the wave of depolarization (starts in mid septum) is greater than the right and is represented as a bigger vector. which ventricle has bigger muscle mass - ANSWER left ventricle degree of perpendicular - ANSWER If the current is running at an angle to the field, the angulation is seen as so much positive and so much negative depending on how parallel and perpendicular the current vector is to the field. The degree of perpendicular can also be seen as a decrease in amplitude only. leads - ANSWER PQRST - ANSWER P wave - ANSWER ATRIAL DEPOLARIZATION Normal: small, round, positive in lead II amplitude 0.5-2.5 mm, 0.10 seconds or less p wave amplitude and time - ANSWER 0.5-2.5 mm 0.10 s abnormally shaped P wave indicates - ANSWER damaged atria (enlarged makes p wave look like an "m") or an impulse origin outside of the SA node (ectopic) notching in P wave indicates - ANSWER atrial enlargement (p mitrale) PR interval normal length - ANSWER 0.12-.20s PR interval - ANSWER Start: beginning of P End: beginning of QRS atrial depolarization and pause before QRS (AV node delay) current traveling quickly down the His and purkinjes shortened PRI - ANSWER bypass pathway or the impulse origin was ectopic and close to the AV node long PRI - ANSWER delays at the AV or His QRS complex normal length and characteristics - ANSWER 0.06-0.12 s BEGIN: first deflection END: flattening before the t (j point) The "classic" QRS complex is composed of three distinct waves: Q wave-the negative deflection following the PRI. R wave-tall positively deflected wave in lead II. S wave-negative deflection following the R wave. abnormal QRS - ANSWER wide, longer than 0.12 s QRS complex - ANSWER DEPOLARIZATION OF VENTRICULAR MYOCARDIUM can take many shapes ST Segment - ANSWER VENTRICULAR DEPOLARIZATION and BEGINNING OF VENTRICULAR REPOLARIZATION BEGIN: J point END: start of t wave should be flat and horizontally lined up with baseline of PRI important for doing 12 lead EKG Abnormal ST segment - ANSWER ST elevation, ST depression, convex (arched upward) or concave (arched downward). Changes in the shape or height above or below the baseline is abnormal and indicative of pathology ST elevation - ANSWER most often a sign of myocardial injury as seen in an acute MI. Other causes include coronary spasm (Prinzmetal's angina) and pericarditis T wave - ANSWER LATTER PHASE OF VENTRICULAR DEPOLARIZATION BEGIN: upward deflection from ST segment END: returns to isoelectric line pile of potassium normal T wave - ANSWER rounded, slightly asymmetrical and positive on lead II abnormal T waves - ANSWER symmetrical and may be tall and peaked, biphasic or inverted seen in MI, ischemia, hyper and hypokalemia, pericardititis, ventricular hypertrophy, and with certain drugs (quinidine, procainamide). atrial repolarization is obscured by - ANSWER QRS QT/QTc segment - ANSWER time between the onset of ventricular depolarization and the end of repolarization BEGIN: beginning of Q END: end of T .34-.43 depends on HR QT segment : general rule - ANSWER QT less than half R-R, usually .44 seconds QT with slower HR - ANSWER longer QT with faster HR - ANSWER shorter prolonged QT segment - ANSWER ventricular repolarization is slowed and the relative refractory period is longer. Long refractory periods potentiates the risk for multifocal VT or Torsades reasons: electrolyte imbalances, left vent hypertrophy, medications. U wave - ANSWER LATTER PHASE OF VENTRICULAR REPOLARIZATION not always present small deflection before P- round, small, symmetrical and positive in lead II abnormal U wave - ANSWER very tall (hypokalemia) inverted ECG paper - ANSWER horizontal axis=time in seconds reads at 25 mm/sec each small box = 0.04 seconds each large box = 0.20 seconds telemetry interpretation - ANSWER 1: Determine the regularity of the rhythm. 2: Calculate the heart rate. 3: Identify and examine P-Waves. 4: Measure the PR Interval 5: Measure the QRS Complex 6: Measure the QT interval step 1 : determining regularity - ANSWER variation of R-R less than 0.12 seconds = regular march out R-R and use it to assess P-P intervals Step 2: calculating HR - ANSWER most will print it mark on top = every 3 seconds count R waves during 6 seconds and multiply by 10 Step 3: P wave/PRI assessment - ANSWER A) P should precede QRS B) should be identical in size, shape, position C) measure PRI and multiply it by 0.04 Step 4: QRS assessment - ANSWER measure QRS and multiply by 0.04 morphology should be identical arrhythmia categorization - ANSWER based on its origin -SA node -Atria -Junction or AV node -Ventricular sinus rhythms - ANSWER -normal -bradycardia -tachycardia -arrhythmia -arrest -block sick sinus syndrome normal sinus rhythm - ANSWER Rate: 60-100 bpm Rhythm: Regular P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) Sinus bradycardia - ANSWER Rate: 60 bpm Rhythm: Regular P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) sinus tachycardia - ANSWER Rate: 101-180 bpm Rhythm: Regular P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) sinus arrhythmia - ANSWER Rate: 60-100 bpm Rhythm: Irregularity associated with respiration phase. P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) sinus exit block - ANSWER Rate: varies Rhythm: Regular except for pause. P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) sinus arrest - ANSWER Rate: varies Rhythm: Regular except for pause P waves: One before every QRS PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) atrial rhythms - ANSWER -wandering atrial pacemaker -premature atrial contraction -nonconducted premature atrial contraction -paroxysmal atrial tachycardia -atrial flutter -atrial fibrillation PACs - ANSWER premature atrial contraction Rate: Depends on underlying rhythm. Rhythm: Underlying regular except during PAC. P waves: P wave before PAC looks different than Ps of the underlying rhythm. PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) Patterns: Bi and trigemeny, couplets and triplets. Wandering atrial pacemaker - ANSWER Rate: 60-100. If rate 101 then rhythm is multifocal atrial tachycardia Rhythm: May be irregular due to changing pacer foci. P waves: One before every QRS. At least 3 different P wave morphologies. PRI: 0.12-0.20 sec QRS: 0.06-0.10(12) SVT - ANSWER supraventricular tachycardia Rate: 150-250 Rhythm: Regular P waves: May not be visible due to rate. If P waves seen, different shape than NSR. PRI: If P is visible, 0.12-0.20 sec QRS: 0.06-0.10(12) SVT may be sustained or in bursts (runs or paroxsyms) atrial fibrillation - ANSWER Rate: Controlled if ventricular rate 100, uncontrolled if 100 Rhythm: Irregular P waves: No Ps, only fibrillation waves between QRSs PRI: None QRS: 0.06-0.10(12) Atrial flutter - ANSWER Rate: Viable. Ventricular rate determined by how well the AV node blocks the flutter. Rhythm: Regular if ratio of flutter wave to QRS is regular. Irregular if variable ratio. P waves: No P waves. Flutter waves may be sawtooth or rounded.