1. Conduction Disturbances: Cardiac Arrhythmias and Heart Block

2. Normal Sinus Rhythm P Wave: 0.08 seconds Normal rate 60-100bpm
Depolarisation starts at the sinus node
All parts of blood flow and conduction are within normal limits
Rate: pbm
Rhythm: Regular
P Wave: 0.08 seconds
QRS: seconds
PR Interval: seconds
QT Interval: 0.42 seconds or less
ST Segment: seconds
T wave: 0.16 seconds

3. Supraventricular Arrhythmias
Sinus Tachycardia
Sinus Bradycardia
Atrial Premature Contractions
Atrial Fibrillation
Atrial Flutter
Sick Sinus Syndrome

4. Sinus Tachycardia Most common tachycardia Often Asymptomatic
Cardiac output can fall secondary to reduced ventricular filling time
ECG findings: rate>100bpm, regular rhythm
Normal physiologic response to exertion, emotional distress, fever
Valsalva maneuver can slow rate
Other causes: anemia, hyperthyroidism, dehydration
Treatment: address the underlying cause
If anemic: correct anemia and tachycardia will correct

5. Sinus Bradycardia Definition: rate <60bpm with a normal rhythm
Symptoms caused by decreased cardiac output and include:
Lightheaded, dizzy, hypotension, syncope, vertigo
May be a normal physiologic response in athletes
Causes: hypothermia, hypothyroidism, sick sinus syndrome, drugs (beta blockers, calcium channel blockers)
ECG findings: rate <60bpm, normal rhythm
treatment,: treat the underlying cause
ie: correct hypothyroidism

6. Atrial Premature/Atrial Premature Contractions
Definition: premature heartbeats originating from the atria
Occurs when another region in the atria depolarizes before the sinoatrial node, firing spontaneously resulting in an earlier beat than expected
May have unifocal or multifocal origins
Symptoms: usually asymptomatic but can feel palpitations
ECG findings: p wave present earlier than expected, abnormal shape to p wave because it is coming from an abnormal focus, normal QRS complex
Treatment: usually benign/no treatment, beta blockers can be used for symptomatic patients

7. Atrial Flutter
Definition: Supraventricular Tachycardia with a sawtooth pattern
Symptoms: may be asymptomatic. Palpitations, chest pain, lightheadeness
Signs: Tachycardia
ECG Findings:
Rate: bpm
Rhythm: atria is regular, ventricle is variable “SAW TOOTH”
Atria depolarization to ventricle depolarization ratio of 2:1,3:1,4:1 or greater
P wave: buried in the QRS complex
QRS: <0.12 seconds

8. Atrial Fibrillation
Definition: rapid, irregular rhythm increasing risk of Stroke, MI, thrombosis
Most common chronic arrhythmia
Symptoms: palpitations, angina, fatigue, CHF. May be asymptomatic
Signs: pulse on exam is irregular and rapid
ECG Findings: Irregularly Irregular.
P waves: Absent p waves; chaotic fibrillatory waves only
Rate: >350bpm with a varying ventricular response from slow to rapid
QRS: <0.12seconds

9. Atrial Fibrillation/Flutter Treatment
3 Foci of Treatment: Rate control, Rhythm control, Anticoagulation
No mortality benefit from rhythm control, thus rate control is the focus
Rhythm control is used primarily in those who are symptomatic
Anticoagulation use is determined by the CHADS2 score or the CHA2DS2- VASc score
CHADS2 is a more commonly used tool though CHA2DS2-VASc is a newer calculator and recent research is showing is to be more sensitive and specific than CHADS2

10. Atrial Fibrillation/Flutter Treatment: Options
Rate Control:
Beta Blocker with or without digoxin
Ca Channel Blocker with or without Digoxin
AV node Ablation and pacemaker
Rhythm Control
Cardioversion via atrial defibrillator
Antiarrhythmic medications
Propafenone, flecainide, sotalol, amiodarone, quinidine, procainamide
Catheter ablation via pulmonary vein
Surgery
MAZE procedure
Anticoagulation
Done for all patients based on the CHADS2 score or CHA2DS-VASc score

11. Atrial Fibrillation/Flutter Treatment: CHADS2 vs CHA2DS2-VASc
CHADS2 Risk
Score
CHF 1
Hypertension
Age >75
Diabetes
Stroke or TIA 2
CHA2DS2-VASc Risk
Score
CHF or LVEF < 40% 1
Hypertension
Age> 75 2
Diabetes
Stroke/TIA/Thromboembolism
Vascular Disease
Age 65-74
Female
Score
Risk
Recommendation
Low
No anticoagulation 1
Moderate
Consider anticoagulation 2
High
Anticoagulation recommended

12. Atrial Fibrillation/Flutter Treatment: Warfarin and NOACs
The anticoagulants available are the traditional warfarin and the new drug class NOACs ((Dabigatran (Pradaxa), Rivaroxaban (Xarelto), Apixaban (Eliquis))
The NOAC have a lower rate of intracranial bleeding compared to warfarin, do not require regular lab testing, is not limited by dietary intake
Most bleeding on NOACs are minor and will resolve on their own with discontinuation of the medication
If a major bleed occurs (although rare,<3%) while taking a NOAC, there is not a direct reversal agent
Warfarin is inexpensive, has lower rates of GI bleeding compared to NOAC, requires regular INR monitoring
Both warfarin and NOACs have major drug interactions
warfarin interacts negatively with most chemotherapy so NOACs are favored in this setting
NOACs have twice the risk of bleeding if combined with ASA or Clopidogrel(Plavix), so warfarin is favored in this setting

13. Atrial Fibrillation/Flutter: Warfarin and NOACs Dosing
Dabigatran (Pradaxa): 150 mg or 110 mg twice daily
Rivaroxaban (Xarelto): 20 mg daily
Apixaban (Eliquis): 5 mg twice daily
Warfarin
Dose changes in accordance with the desired INR range
Goal INR for a patient with atrial fibrillation is

14. Atrial Fibrillation/Flutter Treatment: Bleeding Risk with HAS-BLED
Condition
Points
Hypertension 1
Abnormal Renal or liver function
1 or 2
Stroke
Bleeding
>65 years of age
Drugs or EtOH
Always calculate the bleeding risk in a patient initiating anticoagulation therapy
A score or 3 or higher is considered high risk.
A high risk HAS-BLED score is not a reason to avoid anticoagulation in an patient with Atrial Fibrillation.

15. Sick Sinus Syndrome “tachy-brady syndrome”
Arrhythmia group that encompasses several types of arrhythmias originating from the atria. Commonly alternates between fast and slow.
Signs/Symptoms: BP may be normal to low. Syncope, light-headedness. Can be asymptomatic
Treatment: dual chamber pacemaker is the mainstay of treatment and usually resolves symptoms
ECG findings: Can produce a variety of ECG findings such as: bradycardia, tachycardia, heart block and alternating bradycardia and tachycardia.

16. Ventricular Arrythmias
Ventricular Premature Beats
Ventricular Tachycardia/Torsades de points
Ventricular Fibrillation

17. Ventricular Premature Beats/Contractions
VPCs are extra, abnormal beats that originate from the ventricles
Sign of decreased oxygen to the heart
Signs/Symptoms: palpitations, dyspnea, dizziness. May be asymptomatic.
Treatment: beta blockers, calcium channel blockers, anti-arrhythmic meds. Cardioverter-defibrillator can also be used.
ECG findings: rhythm can be bigeminy, trigeminy, or quadrigeminy.
broad QRS complex (≥ seconds) with abnormal morphology.
occurs earlier than would be expected
followed by a full compensatory pause

18. Ventricular Tachycardia/Torsades de points
A sustained Vtach run is >30/ Torsades has a QRS with a point
Can be difficult to distinguish from supraventricular tachycardia
Pulse may or may not be present
Treatment: Shockable rhythm/CPR
give 1 shock, resume CPR for 5 cycles or 2 min
Shock again followed by epinephrine 1mg IV q 3-5min or vasopressin 40U IV
Shock again and resume CPR for 5 cycles or 2 min.
For Torsades: use magnesium 1-2G IV
ECG findings:
Rate:
Rhythm: regular
P wave: none
QRS: wide and abnormal

19. Ventricular fibrillation
V. fib. Causes cardiac arrest and sudden cardiac death
Occurs when ventricle depolarizes randomly rather than contracting in unison.
Most often occurs in diseased hearts.
Treatment
Defibrillation
Implantable cardioverter
Precordial thump can be given if no defibrillator is available
ACLS: 1 shock followed by CPR for 5 cycles or 2 min followed by shock and CPR with epinephrine 1mg IV or vasopressin 40U IV, Shock and resume CPR for 5 cycles with one of the following:
Amiodarone 300mg IV, then 150mg IV
Lidocaine 1-1.5mg/kg, the mg/kg IV (max 3 doses
Magnesium 1-2g IV for torsade's
ECG findings:
Rate: indeterminate
Rhythm: chaotic
P wave: none
QRS: none

20. Atrioventricular Blocks
1st Degree AV Block
2nd Degree AV Block Type I (Wenkebach)
2nd Degree AV Block Type II (Mobitz II)
3rd Degree AV Block
Bundle Branch Block
RBBB
LBBB

21. First Degree AV Block
The communication between the atrial and ventricular depolarization is delayed. Dysfunction of the AV node
PR interval is prolonged >0.2 seconds
P wave is blocked and conducts to the ventricles
Does not progress to complete heart block
Cause: Electrolyte imbalances, meds (beta-blockers, calcium channel blockers, cholinesterase inhibitors)
Signs/Symptoms: usually asymptomatic.
Treatment: Correct any electrolyte imbalance or hold medication

22. Second Degree AV Block Type I (Wenkebach/Mobitz I)
Intermittent Dysfunction of the AV node
PR interval increasingly prolonged until the QRS is dropped.
QRS is narrow, <0.12 seconds
Treatment: This is usually benign and requires no treatment

23. Second Degree AV Block Type II (Mobitz II)
There is a p wave for every QRS, but now a QRS for every p wave
The QRS is wide, >0.12 seconds
QUICKLY PROGRESSES TO COMPLETE HEART BLOCK!
Treatment: pacemaker

24. Third Degree AV Block
Complete AV disassociation and ventricles kick into to pace the heart
No relationship between p waves and QRS
Slow heart rate
Stokes-Adams Syndrome: 3rd degree AV block has such a slow ventricular rate that blood does not get to the brain and patient loses consciousness.
Signs/Symptoms: syncope, confusion, dyspnea, severe chest pain, sudden death
Treatment: dual chamber artificial pacemaker and ACLS when needed.
Do not give atropine as this drug increases conductivity through the AV node but AV node is not functioning in this case.

25. Left Bundle Branch Block
Blocked left bundle branch which delays depolarization to the left ventricle
One ventricle depolarizes later than the other resulting ins a wide, coupled QRS complex
QRS >0.12 Seconds
Displayed in Leads V5and V6
Treatment: re-synchronization treatment and pacemaker

26. Right Bundle Branch Block
Blocked right bundle branch which delays depolarization to the right ventricle
One ventricle depolarizes later than the other resulting ins a wide, coupled QRS complex
QRS >0.12 Seconds
Displayed in Leads V1 and V2
Treatment: re-synchronization treatment and pacemaker

27. Heart Block Poem From Princeton Surgical Group
If the R is far from P, then you have a First Degree.
Longer, Longer, Longer, Drop! then you have a Wenkebach.
If some Ps don’t get through, then you have a Mobitz II.
If Ps and Qs don’t agree, then you have a third degree.