HAN 417 Cardiac Emergencies Quiz 2, HAN 417 Final Review

Arrhythmia

Abnormal heart rhythm

Ectopic

A beat or rhythm originating from a source other than SA node

- may include the atria, AV junction or the ventricles

Automaticity

The ability of cardiac muscle cells to contract without stimulation from the nervous system.

What can an increase in automaticity cause?

Premature beats and tachycardias

What can a decrease in automaticity cause?

Bradycardia or asystole

Altered automaticity

Condition where a pacemakers cells firing rate is increased beyond its inherent rate, or where a pacemakers cells firing rate is decreased below its inherent rate

Triggered activity

An abnormal condition in which the cells may be triggered to depolarize more than once following stimulation by a single electric impulse

- typically occurs during or after repolarization

Reentry

Impulses travel through an area of the myocardium, depolarize it and then reeneter the same area to depolarize it again

Unifocal PVCs

PVCs that look the same

Originate from a single ectopic site in the ventricles

Multifocal PVCs

PVCs that look different in the same lead

Originate from different ectopic sites in the ventricles

Soemtimes they may fire from the same site but are conducted along different pathways

Bigeminy

Every other beat is a premature ectopic beat

Trigeminy

Every third beat is a premature ectopic beat

Quadrigeminy

Every fourth beat is a premature ectopic beat

Couplet

Two consecutive premature beats

Non-sustained ventricular tachycardia (NSVT)

3 or more consecutive premature beats

Interpolated PVC

A PVC sandwiched between 2 normally conducted sinus beats without greatly disturbing the underlying rhythm

Synchronized cardioversion

Delivery of a timed electrical shock to reset an abnormal rhythm

- Shocks are synchronized with the hearts R Wave!!!!

Once a shock is delivered, you must press "SYNC" agaon before deliverying another shock

- Unstable SVT, Rapid Afib/Aflutter, Vtach with a pulse

What is synchronized cardioversion used for?

Unstable SVT, Rapid Afib/Aflutter, VTach w a pulse

Defibrillation

Shocks are random and do not line up with any specific wave

Transcutaneous Pacing

External cardiac pacing

- consists of 2 electrode pads placed Anterior-Posterior on the pt's chest to conduct electrical impulses through the skin to the heart

What do we use transcutaneous pacing for?

Symptomatic bradycardia, unstable heart blocks

Junctional Rhythms (General)

Pacemaker cells in this junction have automaticity and have an intrinsic firinf rate of 40-60 bpm

-inverted P waves in Lead 2

- PR Interval is short

- QRS complex is normal

In general junctional rhythms where do they originate

Originate in AV node

In general junctional rhythms the AV junction is functioning as the primary pacemaker the impulses travel which way to depolarize the atria?

Backwards

In general junction rhythms due to the short distance between the AV junction and the atria, what does that tell us about the PR interval?

It will be short

In general junctional rhythms the P waves occur in 1 of which 3 patterns?

- Immediately before the QRS

- Immediately after the QRS

- Hidden within the QRS

What are the distinguishing features of junctional rhythms?

The inverted Pwaves in lead 2 that may appear before, within or after the QRS complex

Accelerated Junctional Rhythm

A rhythm that originates in an ectopic site in the AV junction discharging impulses at 60 to 100 bpm

- "Accelerated" denotes a faster rate than a junctional rhythm, but not fast enough to be considered junctional tachycardia

What is the distinguishing features of accelerated Junctional rhythms?

Inverted P waves in lead 2 that may appear before, within or after the QRS complex

Junctional tachycardia

A rhythm that orignates in an ectopic site in the AV junction discharging impulses greater than 100 bpm

What is the distinguishing features of accelerated junctional rhythms?

Inverted P waves in lead 2 that may appear before, within or after the QRS Complex

What are the characteristics of ventricular arrhythmias?

-Originate from below the bundle of His

-No P waves

-Impulses do not enter the normal conduction pathway

-Conduction of impulses is slower as they travel from muscle fiber to muscle fiber

QRS complex in Ventricular Arrhythmias

QRS is wide

> 0.12 seconds (3 small boxes)

Premature Ventricular Contractions characteristics

- Premature

- P waves are not associated with PVC

- QRS complex is wide

- ST-segment and T wave are usually in opposite directions

The pause that follows the PVC (Premature Ventricular Contraction) is called?

Compensatory pause

When diagnosing PVC what must you know?

The premature beat occurs IN ADDITION to the regular beat so when diagnosing you must include both

-"normal sinus rhythm with PVC"

Idioventricular Rhythm

A very slow rhythm originating in the ventricles at the rate of 30=40 bpm

- rhythm appears regular but does not have Pwaves

- nonmeasurable PR interval

- QRS is wide, ST segment and T wave are in opposite direction of the QRS complex

- Usually a continuos terminal rhythm but may occur intermittently

What rhythm is very difficult to resuscitate and usually progresses to asystole?

Idioventricular rhythm

What are atonal rhythms?

When the rhythm becomes irregular, slower, and QRS begin to widen and deteriorate into indistinguishable waveforms

Accelerated Idioventricular Rhythm

Discharges impulses at a rate of 50-120 bpm

- Looks the same as IVR and Vtach, just differentiated by heart rate

Ventricular Tachycardia

Originates from an ectopic site in the ventricles discharging impulses at a rate of 140-250 bpm

Has the same appearance as IVR and AIVR but is differentiated by heart rate

*MONOMORPHIC

POLYMORPHIC

Torsades de Pointes*

What is monomorphic

QRS complexes have the same morphology

- most common form of Vtach

- Occurs as a continuous rhythm or intermittent runs of 3 or more consecutive ventricular beats

What is polymorphic

QRS complexes have different morphologies in the same lead

Torsades de Pointes

A type of polymorphic Vtach

- distinguishing characteristic is QRS complexes "twist" around the isoelectric line

Ventricular Fibrillation

Rhythm originating in multiple sutes in the ventricles characterized by erratic electrical activity which takes over control of the heart

- the ventricular muuscle quivers instead of contracting, producing wavy, irregular deflections with no discernable waves or complexes

Always considered symptomatic

- Once VF occurs there is no cardiac output, peripheral pulses or BP

Coarse Vfib

Vfib with large deflections

Fine Vfib

Vfib with small deflections

Asystole

There is no ventricular actiivyt and thus no QRS complexes, basically a straight line

- there still may be atrial activity presenting in the form of a P wave

- may be represented as a straight line "flatline" or Pwaves absent of QRS complexes

Pulseless Electrical Activity (PEA)

Clinical situation where there is organized elecrical activity seen on the monitor but there is no plapable pulse

-You may observe NSR on the monitor but if there is no pulse, this is PEA

What are the causes and treatments for PEA?

Same as asystole

AV Blocks

A group of rhythms that originate in the sinus node and will have a normal P wave

- used to describe rhythms in whihc there is a delay or block in the conduction of impulses from the Atria to ventricles

What are the classifications of AV blocks

1st degree

2nd degree (type I Mobitz/Wenckebach, type II Mobitz)

3rd degree

1ST DEGREE AV block

The impulse is delayed more than normal at the AV node before being conducted to the ventricles

- although the impulse is delayed, they are still conducted to the ventricles

- this delay results in a PR interval that is greater than 0.20 seconds

- underlying rhythm should be identified with block

2nd Degree Type 1 (Mobitz 1) AV Block

- Each impulse has increasing difficulty passing through the AV node

- eventually the impulse cannot pass through the AV node so there is no impulse conducted to the ventricles

How are 2nd degree Mobitz 1 AV blocks reflected on the EKG?

P waves that occur in regular intervals and PR intervals that progressively get longer and longer until an impulse is not conducted to the ventricles

- "wider, wider, wenckebach"

2nd degree Type 2 (Mobitz 2) AV block

- P-P is always regular

- R-R is regular until non-conducted beat

" If the P's dont get through - Mobitiz 2"

- If the location is at the bundle of His, the QRS Duration will be normal

- if the location is at the level of the Bundle branches, the QRS duration will be wide

3rd degree AV block

"Complete Heart Block"

- atria and ventricles beat independently of each other (different pacemakers)

- atria is typically paced at 60-100 bpm

- ventricles are typically paced at 40-60 bpm, sometimes less

"If the P's and Q's dont agree = Type 3/Complete AV"

Cardiac Anatomy

Cone shaped muscle:

- Four Chambers (2 atria, 2 ventricles)

What kind of pump is the heart?

double pump

Systemic

Blood vessels that transport blood to and from body tissues

Pulmonary

Blood vessels that carry blood to and from the lungs

How do the circulations in the heart work?

Pressure gradients

Chamber of the heart: Atria

Two Atria

- Right atrium

- Left atrium

Divided by the interATRIAL septum

Chamber of the heart: Ventricles

Two Ventricles

- Right Ventricle

- Left Ventricle

- Divided by the interVENTRICULAR Septum

What are the heart valves?

Atrioventricular, Bicuspid, Tricuspid, Semilunar.

Tricuspid Valve

right atrium and right ventricle

Pulmonic Valve

Right ventricle to pulmonary trunk

Mitral Valve (Bicuspid)

Left atrium to Left ventricle

Aortic Valve

Left ventricle to aorta

What are the Coronary Arteries?

right coronary artery and left coronary artery

Posterior descending artery

Left circumflex artery

Right Coronary Artery (RCA)

Feed right ventricle and Apex

- SA & AV nodes

Left Coronary Artery (LCA)

Feeds

- anterior wall of the left ventricle

- septum

- part of the right ventricle

Posterior Descending Artery (PDA)

feeds inferior wall and part of septum

Left Circumflex artery (LCx)

Feeds:

Lateral and posterior walls of:

- Left ventricle

- Left atrium

Start CPR?

if a person has no pulse and no breathing

When to utilize AED?

Unconscious

Not Breathing

No pulse

Epinephrine is used when in?

Cardiac Arrest

Heart Failure

Shock

Amiodarone

Ventricular Fibrillation & Ventricular Tachycardia

Atropine

symptomatic bradycardia

Adenosine

supraventricular tachycardia SVT

Diltiazem

Rapid Afib/Aflutter

Metoprolol

Rapid Afib/Aflutter

Path of electrical conduction in the heart?

- SA Node

- Internodal Atrial Conduction Tract & Bachmann's Bundle

- AV Node

- Bundle of His

- Left & Right Bundle Branches

- Purkinje Fibers

What does the PR Interval represent?

Represents the time from the onset of atrial depolarization to ventricular depolarization

What does the PR segment represent?

Normal delay in the AV Node

What does the QT interval represent?

total time for ventricles to depolarize and repolarize

What does the ST segment represent?

ventricular repolarization

P wave

atrial depolarization (atrial contraction)

First segment seen

QRS Complex

ventricular depolarization

Second wave seen

Pathological Q wave often represents old MI

T wave

ventricular repolarization

Third segment seen

Reflects the hearts recovery phase and can indicate abnormal cardiac issues

Positive deflections

A current moving towards the positive pole

Above the baseline

___/\___

Negative Deflection

A current moving towards the negative pole

Below the baseline

—-\/—-

Biphasic deflection

Currents moving away from both the + and - poles but the amplitude of deflection can vary

A waveform that is both above and below the baseline

Bipolar leads are

I, II, and III (einthoven's triangle)

Bipolar Lead: Lead I

Lead I: Right arm - to left arm +

Measures horizontally across the heart

What wall does Bipolar Lead I look at?

Lateral Wall

Bipolar Lead: Lead II

Lead 2: Right arm - to left leg +

Aligns with natural depolarization process

What wall does Bipolar Lead II look at?

Inferior Wall

Bipolar Lead: Lead III

Left arm - to left leg +

What wall does Bipolar Lead III look at?

Inferior Wall