EKG Review Blog

Other Arrhythmias

noreply@blogger.com (Anonymous) — Tue, 17 Dec 2013 07:28:00 +0000

Ventricular Tachycardia-
-appears like a run of PVC's
-usually is significant for coronary artery disease or poor oxygenation of the coronaries
-originates from a single ventricular ectopic focus
-rate 150-250 beats per minute

Ventricular Fibrillation-
-disorganized rhythm of multiple ectopic ventricular foci
-needs to be defibrillated

Torsades de Pointes-
-"Turning on a point"
-can be from magnesium deficiency

Atrial Flutter-
-originates from a single atrial ectopic focus
-Atrial rate of 250-350 beats per minute
-saw tooth pattern

Atrial Fibrillation-
-originates from multiple atrial foci
-atrial rate of 350-450 beats per minute
-irregularly irregular rhythm

Miscellaneous

noreply@blogger.com (Anonymous) — Tue, 17 Dec 2013 07:13:00 +0000

Pulmonary Embolus-
-Commonly see large S wave in lead I, ST depression in lead II, and a Q wave with an inverted T in lead III.
-there is commonly T wave inversion in lead V1-V4
-may cause a right bundle branch block

Hyperkalemia
-with elevated K the P wave is flattened, the QRS complex is widened, and the T wave becomes peaked

Hypokalemia
-with low K the T wave becomes flattened, and there can be a U wave

Hypercalcemia
-the QT interval becomes shortened

Hypocalcemia
-the QT interval becomes prolonged

Ischemia, Injury, and Infarction

noreply@blogger.com (Anonymous) — Tue, 17 Dec 2013 06:01:00 +0000

Myocardial Ischemia-
-when myocardial oxygen supply does not meet demand.
-there is no tissue death
-the T wave is inverted or ST segment is depressed
-since the ventricles are closest to the chest leads, the T wave changes will be most prominent there

Injury-
-Injury indicated the acuteness of an infarct
-the ST segment elevation denotes injury
-the ST segment may be only elevated as much as 10 or more mm above the baseline

Infarction-
-if there is a ST elevation, this means that the infarction is acute
-the ST segment will elevate with an acute infection, and then return to the baseline
-Pericarditis can cause diffuse ST segment elevation
-A ventricular aneurysm can cause ST segment elevation
-The diagnosis of a MI is usually made by the presence of Q waves with the St elevation
-It is important to be able to recognize the location of the infarction

Anterior STEMI
-See ST elevation in leads V1, V2, V3, and V4. V1 and V2 is sometime referred to as septal leads

Lateral STEMI
-See ST elevation in leads I, avL, V5 and V6. Will see Q waves

Inferior STEMI
-See ST elevation in leads II, III and avF and Q waves

Posterior Wall STEMI
-there is ST depression in leads V1 and V2
-since the posterior wall of the left ventricle depolarizes in a direction of the anterior infarction

Hypertrophy

noreply@blogger.com (Anonymous) — Tue, 17 Dec 2013 05:26:00 +0000

Hypertrophy-
-Refers to increase in size and muscle mass

Atrial Hypertrophy
-since the P wave denotes contraction of both atria we look at the P wave to determine hypertrophy
-Lead V1 is directly over the atria, so it is the best indicator of hypertrophy
-With atrial hypertrophy we have a biphasic P wave in V1
-If the initial component of the P wave in V1 is the largest, it is right atrial hypertrophy
-If the terminal portion of the biphasic P wave in lead V1 is large and wide, this is left atrial hypertrophy

-Right Atrial Hypertrophy

-Left Atrial Hypertrophy

Right Ventricular Hypertrophy-
-See a large R Wave in lead V1
-With RVH there is more positive deflection toward the V1 electrode and would expect the QRS complex more upright than normal
-The S wave in lead V1 is smaller than the R wave
-The R wave gets progressively smaller in leads V2-V6

Left Ventricular Hypertrophy-
-Hypertrophy of the left ventricle causes QRS complexes to be bigger in both height and depth in leads V1-V6 (chest leads)
-The S wave will be even deeper in V1
-In LVH there is a large S wave in lead V1 and large R wave in lead V5
-Lead V5 is directly over the left ventricle
-The T wave often shows inversion or asymmetry

Axis

noreply@blogger.com (Anonymous) — Tue, 17 Dec 2013 05:01:00 +0000

Axis
-Refers to the direction of electrical depolarization
-It is determined by the direction of the QRS complex in lead I and avF

Normal Axis
-Positive deflection of QRS complex lead I
-Positive deflection of QRS complex lead avF

Left Axis Deviation
-Positive deflection of QRS complex in lead I
-Negative deflection of QRS complex in lead avF

Right Axis Deviation
-Negative deflection of QRS complex in lead I
-Positive deflection of QRS complex in lead avF

Extreme Right Axis Deviation
-Negative deflection of QRS complex lead I
-Negative deflection of QRS complex lead avF

Heart Blocks

noreply@blogger.com (Anonymous) — Mon, 16 Dec 2013 21:47:00 +0000

Heart Blocks Can occur in the SA node, AV Node, or in larger sections of the ventricular condition system

Types of Heart Blocks:
1. Sinus Block
2. AV Blocks
3. Bundle Branch Blocks
4. Hemiblocks

Sinus Block-an unhealthy SA node quits pacing activity for at least one compete cycle. The P waves before and after the block are identical because the same SA node pacemaker is functioning before and after the pause.

AV Blocks-when minimal delays the impulse within the AV node, making a longer than normal pulse before stimulating the ventricles.
-Types of AV Blocks
1. First Degree AV Block
2. Second Degree AV Block Type I
3. Second Degree AV Block Type II
4. Third Degree AV Block

First Degree AV Block-prolonged PR interval greater than 0.2 seconds. There is no dropped QRS complex

Second Degree Type I AV Block-the PR interval become lengthened until the P wave does not elicit a responding QRS complex. The PR interval is greater than 0.2 seconds. Also called Wenckebach

Second Degree Type II AV Block-also called Mobitz II is when an occasional ventricular depolarization (QRS complex) is not conducted but dropped. The P waves are normal and normal PR intervals are present.

Third Degree AV Block-also called complete heart block. This is when none of the atrial depolarizations conduct to the ventricles. The P wave rate and the QRS complex rate are independent and will march out with calipers uniformly.

Bundle Branch Blocks-
-Normally the right and left bundles transmit the electrical change to the right and left ventricles at the same time.
-When there is a bundle branch block, there is a delay in the depolarization stimulus that creates the widened QRS complex in the classic rabbit ear pattern (R and R' waves)
-If there is a bundle branch block, look at the chest leads right (V1 and V2) and left (V5 and V6)

Right Bundle Branch Block
-If there is a R,R' waves in V1 or V2 there is a right bundle branch block
-If it is only present in one of the leads it is an incomplete right bundle branch block

Left Bundle Branch Block
-Sometimes the R R' waves will only be seen as notch in the wide QRS complex in V5 and V6
-In a left bundle branch block the left ventricle fires late so the first portion of the QRS complex is right ventricle activity. We cannot see Q waves originating from the left ventricle because they are buried in the QRS complex

Right Bundle Branch EKG:

Left Bundle Branch EKG:

Wolff Parkinson White:
-There is an accessory pathway for ventricular stimulation causing a delay in ventricle stimulation
-This occurs between the SA node and AV junction
-This produces a delta wave
-These patients are prone to SVT

Delta Wave:

Hemiblocks:
-These are blocks of the anterior and posterior division of the left bundle branch
-These are mostly due to loss of blood supply to the anterior or posterior branches of the left bundle branch

Rate

noreply@blogger.com (Anonymous) — Mon, 16 Dec 2013 16:28:00 +0000

Rate-

-Normal Rate from SA Node 60-100

-Bradycardia- rate less than 60 originating from the SA node

-Tachycardia- rate greater than 100 originating from the SA node

-When the pacemaker changes from the SA node it is referred to as an ectopic focus (different pacemaker)

-AV Node (Junctional Ectopic Focus)- also called junctional rhythm when comes from here. Has an inherent rate of 40-60 beats per minute. Faster than 60 is called junctional tachycardia. Slower than 40 is referred to as junctional bradycardia.

-The ventricles have ectopic foci and are potential pacemakers. The ventricular ectopic foci have an inherent rate of 20-40 beats per minute

Rhythm

noreply@blogger.com (Anonymous) — Sun, 15 Dec 2013 19:54:00 +0000

Normal Sinus Rhythm=equal distance between similar waves (P, QRS, and T waves)

Four Varieties of Arrhythmias
1. Sinus Arrhythmia- the pacemaker still originate from SA node but the pacemaking activity is irregular varying with inspiration and exhalation

2. Wandering Atrial Pacemaker-the pacemaker wanders from focus to focus. The P waves are various shapes since the origin of the pacemaker varies from within the atria.

3. Atrial Fibrillation-multiple ectopic foci in the atria emit electrical impulses. Since no single impulse depolarizes both atria there is a rapid series of tiny waves

4. Escape Beat-the response to a pause in pacemaking activity. Premature beats are made by an ectopic focus discharging spontaneously causing a beat earlier than expected.

Premature Beats
1. Premature Atrial Contraction (PAC)-originates from an ectopic focus in the atrium that appears much earlier than normal P wave on an EKG

2. Premature Junctional Contraction (PJC)-originates in an ectopic focus in the AV junction which fires before the normal cycle. Usually inverted P wave occurring before, during, or immediately after the QRS complex

3. Premature Ventricular Contraction (PVC)-originates from an ectopic focus, an occurs very early before a P wave.

With Premature beats there usually is a compensatory pause.

Tachycardias
1. Paroxysmal Atrial Tachycardia-a rapid sudden heart rate originating from an ectopic focus from on of the atria. The rate is usually between 150-250 beats per minute.

2. Paroxysmal Junctional Tachycardia-a rapid sudden heart rate originating from an ectopic foci in the AV junction. The P wave is inverted occurring before, during or immediately after the QRS complex. Rate is between 150-250 beats per minute

-Collectively PAT and PJT are referred to as supraventricular tachycardia

3. Paroxysmal Ventricular Tachycardia-sudden ectopic focus occurring from the ventricles. Wide complex. Rate between 150-250 beats per minute

4. Atrial Flutter-the ectopic focus in the atria fires at a rate between 250-350 beats per minute. There is one ectopic focus that is why the p waves look the same. The QRS complexes are usually equal distances between each other

Basic EKG Tracing

noreply@blogger.com (Anonymous) — Fri, 13 Dec 2013 15:23:00 +0000

EKG Waves:

-P Wave-atrial depolarization
-QRS Complex-ventricular depolarization
-T Wave-ventricular repolarization
-U Wave-atrial repolarization (often absent)

-Upward deflection of the QRS complex is referred to as a positive deflection
-Downward deflection of the QRS complex is referred to as a negative deflection

Normal PR Interval-0.12-0.2 seconds (3-5 small boxes)

Normal QRS Complex-less than 0.12 seconds (less than 3 small boxes)