cardiac ekg 1

atrial depol

from start of P to R's divot

the delay of current as it runs through the AV node and Bundle of His and Purkinje fibers

 ventricular depol

ventricular isoelectric period

from the the J point (the place where the the slope btwn S and T changes/flattens most dramatically) to the start of T

ventricular repol

• V1: 4th IC R sternal border
• V2: 4th IC L sternal border
• V3: btwn V2 and V4
• V4: 5th IC in the nipple line or under the boob

• V5: 5th IC midaxillary line
• V6: 5th IC under armpit

voltage

• 0.04
• so a bundle of 5 is 0.2 sec

5 big blocks

• from start of P to R
• .12-.2 sec 
• 3-5 little boxes

• .04-.10 sec
• 1-2.5 boxes

(anything much over .1 sec) the signal is taking longer than it should to get thru the ventricle due to damage to the ventricle ... MI

• .32-.4 sec
• 8-10 little boxes
• from start of QRS to end of T

positive, and vice versa

R hand to L hand (+ --> -)

R hand to L foot (+ --> -)

Left hand to foot (+ --> -)

• AVR, AVL, AVF
• each is an average of the leads going toward it (maybe maybe?)

AVR doesn't give much signal bc the electricity goes L, away from it, so we sometimes don't look at that lead

frontal

anterior/posterior view of the heart

• Anteroseptal: V1-2
• Anterior: V1-4
• Extensive anterior: V1-6, I aVL
• Anterolateral: V3-6, I aVL
• High lateral: I, aVL
• Inferior: II, III, aVF
• Posterior: V1, V2 (ST depression, tall R waves noted)

• fixed length - that's a sign of dysrhythmia
• it should vary in length as you exercise

• distance from R to R
• QRS complex should look the same each time
• P wave intervals

• count out 30 big squares - this equals 6 seconds
• count the R peaks in this distance
• multiply that by ten

1500 divided by the number of small boxes between Rs

300 150 100 75 60 50 etc and then subdivide for the smaller boxes

• 1) check to see if it's regular - equal distances between R intervals?
• 2) calculate HR
• 3) check for all components of the PQRST - present? are the timings roughly right?

atria

ischemia - but you can't do more than suspect until you see another view / another EKG angle

longer QRS complex for life

anticoagulants to limit the clots

• AV - 40-60 bpm
• ventricle 20-40 bpm - and it'll have a qider QRS

• QRS is normal
• absense of P wave
• happens when pulse is coming from AV node

the rhythm is originating above the AV node

• rhythm originates from SA node
• varies from 60-99 bpm

• < 60 bpm
• regular rhythm, P wave present, 1 p wave per QRS, timing of segments is right

• can be normal in athletes
• for others, may lead to inadequate cardiac output --> tiredness, lightheadedness, syncope

• diastolic period is shortened, so less time for ventricular and coronary artery filling, acna --> hypotension, angina, palpitations, or dizziness
• increased workload for heart requires more O2 consumption ... so big concern for the post MI pt
• this is >100bpm at rest, > 210 at exercise

a tachycardia originating above the ventricle -- you can call it this any time you have tachychardia with a normal looking QRS

a rhythm in which an ectopic atrial focus causes the atria to fire at a rate of 250-350 bpm

it blocks some of the atrial impulses, letting only every 2nd to 5th be conducted

• atrial rate: 250-350 bpm
• ventricular rate: 60-150 bpm depending on conduction thru AV node

may be regular or irregular, depending on the conduction thru the AV node (fixed vs variable block)

• present, more than 1 btwn QRS complexes
• looks like a saw toothed pattern
• all have the same shape bc they come from one focus

• the effect of the arrhythmia depends a lot on the ventricular response rate
• if it's fast: my compromise ventricular filling and coronary artery blood flow --> syncope, angina, CHF, PE, or hypotension
• if slow: may provide inadequate perfusion

they'll look the same, less that .1 sec, but they'll be varying distances apart, so the HR will seem to fluxuate a lot

• multiple atrial ectopic foci cause the atria to fire 300-400 bpm (in flutter it's from a single ectopic focus)
• the combo of all this firing leads to an erratic quivering of the atria w no effective atrial contractions, so no clear P waves, just a scratchy line btwn QRSes

it's irregular bc it's getting a shitstorm of impulses from the atria

• atrial rate is 300-400 bpm but difficult to count
• ventricular rate depends on the vent's response to the atrial ectopic foci

pt prob isn't on anticoagulants, so the atrial fib puts the pt at risk of a stroke

don't worry, it's only worrisome if the irregularity comes in a pattern (this is a ventricular arrhytmia)

• premature ventricular contraction
• if back to back and not same shape, this is a multifocal problem and therefore worrisome

• premature ventricular contraction
• no P wave, wide QRS, inverted T
• (ventricle is contracting before it fills)

• fancy name for when every second heart beat is a PVC
• one will be pos, one neg (above/below isoelectric line)

use the inferior QRSes bc the upper ones don't have enough filling time

30

• sinoatrial impulse is delayed longer than normal at the AV node before being transmitted to the ventricles, so...
• bigger distance than usual btwn P and QRS

• usually transient
• transmission of impulse across AV node is delayed, not blocked
• if associate w an MI, the pt should be monitored for progression to higher degree AV blocks