introduction to ekg
DESCRIPTION
Introduction to EKG. And then a little more. To get an accurate EKG, leads must be properly applied:. aVR: RA(-) to [LA & LL(+)] aVL: LA(+) to [RA & LL(+)] aVF: LL(+) to [RA & LA(-)]. I: RA(-) to LA(+) II RA(-) to LL(+) III:LA(-) to LL(+). Precordial lead is +. Normal activation. - PowerPoint PPT PresentationTRANSCRIPT
Introduction to EKG
And then a little more
• To get an accurate EKG, leads must be properly applied:
I: RA(-) to LA(+)II RA(-) to LL(+)III:LA(-) to LL(+)
aVR: RA(-) to [LA & LL(+)] aVL: LA(+) to [RA & LL(+)]aVF: LL(+) to [RA & LA(-)]
Precordial lead is +
• Normal activation
• Interpretation:– Rhythm: look for P waves, regularity, reproducible intervals, PR
interval, shape– Rate– Axis– Intervals: PR, QRS, QTc– Conduction – R wave progression– ST segments and T waves– Ectopic beats– Q waves: where they should and should not be– Other stuff
• Some general guidelines:– P waves
• Best seen in lead II• Upright or biphasic (neg component smaller) in V1-V2, upright in V4-V6
– QRS complex• V1 shows rS, V6 shows qR• Size of r wave progressively increases, transition V3-V4• QRS duration < .120 sec• One R wave in precordial leads should be > 8mm• No R wave in precordial leads > 27mm• Sum of tallest R in left leads and S in right leads should be < 35-40mm• Precordial q waves should not exceed .04 sec nor have a depth greater than ¼
the height of the R wave following• R wave in aVL <12-13mm
– ST segment• Should not be more than 1mm above or below baseline. Normal minor
elevation in leads with large S waves ( V1-V3) and normal configuration is concave up.
• T waves– Often inverted in V1. May be inverted in V2 if already inverted in V1.– Always upright in leads I, II, V3-V6– Always inverted aVL
• U waves– Amplitude usually < 1/3 T wave height in same lead– Direction is same as T wave in that lead
• Axis– Frontal plane lead with the sum of r wave and s wave most
closely approximates 0.– Look at QRS in the lead perpendicular to original lead– If QRS id positive, axis along that direction. If negative, axis
in opposite direction.
• Axis- contNormal axis
Left axis
Right axis
• Heart block– Normal PR interval < .2 sec– 1st degree AV block- prolonged PR
• Heart Block– 2nd degree AV block- Wenchebach- Mobitz 1• Prolonged PR until dropped QRS• 1st PR interval always the shortest• 1 dropped QRS only• RR intervals shorten
• 2nd Degree- 2 to 1 block
• 2nd degree type 2- mobitz 2
• Complete heart block
• Bundle branch block– QRS > .120 sec– RBBB- R-R’ in V1-V2, s wave in lead 1 & V6
• LBBB– QRS >.120 sec– Neg QRS in V1– Lack of small q in lead 1, V5-V6