Bradycardia and Narrow Bradycardia and Narrow Complex TachycardiaComplex Tachycardia

Smriti BanthiaSmriti BanthiaCCU Lecture SeriesCCU Lecture Series

• Sinus node is supplied by the RCA in 60% of people and by the LCX in 40%.

• AV node is supplied by the RCA in 90% and by the LCX in 10% of patients.

• Right bundle supplied by LAD

• Left bundle supplied by branches of the RCA and LAD

Zimetbaum PJ, Josephson ME. NEJM, 2003Taken from www.baptistoneword.org

Conduction System Anatomy

Pacemaker?

• Progressive shortening of PP interval before it blocks

• Pause is less than 2 of the preceding PP intervals

Pacemaker?

SA Block Type II – Pause approximately 2x PP interval

WHAT NEXT?

52 year-old obese man who presents with cellulitis. Above seen on telemetry during hospitalization.

Page…. HR 30. WHAT NEXT?

WHAT IS THIS?

Premature junctional complex

Retrograde p wave

WHAT NEXT?

80 year-old man presents with syncope.

Mobitz II – 2nd Degree AV Block

What’s the rhythm?

NSR with first degree AV block

Pause duration to meet criteria for pacemaker implantation?

3 seconds

Post cath, holding groin pressure. Pt dizzy now. WHAT NEXT?

Sinus Bradycardia.

Vagal response. Give Atropine.

What is the rhythm?

ATRIAL FIBRILLATION

Management of AF

• Maintenance of normal sinus rhythmNo treatmentPharmacologic therapy (AAD, anticoagulants)Non-pharmacologic therapy (Ablation, PPM)

• Ventricular rate controlPharmacologic therapy (BB, CCB, Digoxin)Non-pharmacologic therapy (AVN ablation)

• Reduction of thromboembolic risk

What’s wrong?

• Leading cause of stroke from embolism

• AF increases stroke risk

~ 17x Rheumatic heart Dz

~ 5x in non-valvular

Risk of stroke ~ 5%/yr

• Proportion of strokes attributable to AF increases with age

AFIB AND STROKE

When Rx Coumadin?

ASA 325 dailyASA or Coumadin

Coumadin INR 2-3

Problem: What about pt with prior hx of CVA but no other RF? Classified as moderate risk when in fact may be high risk…. Thus, the ACC/AHA guidelines differ in the following way…

ACC/AHA Guidelines for Anticoagulation

Tachy-Brady Syndrome

32 year-old female with palpitations

WHAT NEXT???

After Adenosine 6mg IV

Retrograde p waves

CSM/Vagal Maneuvers

Adenosine

BB/CCB

Ablation

AVNRT – Mechanism?

Aflutter with variable conduction

MAT

Aflutter with 4:1 Block

Most cases of atrial flutter are caused by a large reentrant circuit in the wall of the right atrium

EKG Characteristics: Biphasic “sawtooth” flutter waves at a rate of ~ 300 bpm

Flutter waves have constant amplitude, duration, and morphology through the cardiac cycle

There is usually either a 2:1 or 4:1 block at the AV node, resulting in ventricular rates of either 150 or 75 bpm

Unmasking of Flutter Waves

In the presence of 2:1 AV block, the flutter waves may not be immediately apparent. These can be brought out by administration of adenosine.

Atrial Tachycardia

Atrial tachycardia

• P wave upright lead V1 and negative in aVL consistent with left atrial focus.

• P wave negative in V1 and upright in aVL consistent with right atrial focus.

• Adenosine may help with diagnosis if AV block occurs and continued arrhythmia likely atrial tachycardia

• 70-80% will also terminate with adenosine.

WHAT IS THIS?

•A. Emergent cardioversion for polymorphic VT.

•B. I.V. procainamide

•C. I.V. lidocaine

•D. diltiazem drip to obtain rate control.

WPW epidemiology• Present in 0.3% of the

population• Risk of sudden death 1

per 1000 patient-years• Sudden death due to

atrial fibrillation with rapid ventricular conduction

• Atrial fibrillation often induced from rapid ORT

ORT(orthodromic reciprocating tachycardia

Atrial Fibrillation and WPW

• AV nodal blocking agents may paradoxically increase conduction over accessory pathway by removing concealed retrograde penetration into accessory pathway. Concealed penetration into the

pathway causes intermittent block of pathway conduction

Management of Atrial Fibrillation with WPW

• Avoid AV nodal blockers

• IV procainamide to slow accessory pathway conduction

• Amiodarone if decreased LVEF

• DC cardioversion if symptomatic with hypotension