Usually this block is above His bundle
Second degree - some P waves are not followed by QRS. Often has a regular sequence, i.e., 2:1 or 3:2. The first number is the number of P waves present and the second is the number of QRS’s.
Ectopic Atrial Tachycardia (Long RP tachycardia)
• Uncommon cause of paroxysmal SVT in the young adult (< 5%)
• Occurs in a small region of either the right or left atrium • Frequently due to an automatic mechanism making it difficult to reproduce in EP Lab
This is unambiguously Mobitz II
It is a dangerous arrhythmia because the heart may suddenly start beating very slowly or even stop.
Complete heart block. Since there is no conduction down the AV node pathway atria and ventricles beat regularly but at different rates.
AP)
Other
A Flutter
JET
Figure 18.16
Sinus Tach
EAT
Primary Atrial
A Flutter
Junctional Tachycardias
AVNRT
JET
Fig 12 a summary of heart blocks.
Look at the QRS morphology in V1 and V6
Electrophysiology II – Supraventricular Arrhythmias
Atrial Flutter
“Typical isthmus dependent atrial flutter” is due to a macro reentrant circuit around the tricuspid valve
Accessory Pathway Mediated Tachycardias
(AV Reentry)
AV Node RT AV RT (ORT) 95% of adults 95% of infants
Manolis, Ann IM, 1994
Arrhythmias
Ventricular fibrillation
The accessory pathway activates the ventricle before normal activation via the AV node.
The PR interval is <0.12 sec Delta waves are usually present
Can get retrograde conduction causing reentry and a tachyarrhythmia.
• This rhythm can be stopped by pacing and cured with ablation
• Embolic risk may be less than in fibrillation, but same recommendations apply
Electrophysiology II – Supraventricular Arrhythmias Ventricular rate 150 bpm
“Saw tooth” p waves
Atrial Flutter
Electrophysiology II – Supraventricular Arrhythmias
Atrioventricular Nodal Reentrant Tachycardia (AV Node Reentry or AVNRT)
a summary of other arrhythmias
Wolff-Parkinson-White Syndrome
Tachycardias
CC5 CM5 ML
Adequacy of Anticoagulation in Patients with AF in Primary Care Practice
Wolff-Parkinson-White Syndrome
• Relatively common cause of paroxysmal SVT in children and young adults
• Due to an “extra” muscular bridge that connects the atrium and ventricle and allows the ventricle to be “excited” before the signal passing through the AV Node
Atrium (P wave)
Non-visible process on the EKG
AV node
IVC
Lead II
“Slow zone”
SUMMARY
Mechanisms of SVT
SP
FP
Atrial Tachycardia AVNRT
AVRT
P QRS T
Bundle branch blocks
Electrophysiology II – Supraventricular Arrhythmias
Rate of 145 bpm
Retrograde p waves RP = 60 msec
AV Node Reentry Tachycardia (Short RP tachycardia)
Electrophysiology II – Supraventricular Arrhythmias
INR above target 6%
INR in target range
15%
Subtherapeutic INR 13%
Samsa et al. Arch Intern Med. 2000;160:967-973.
Regional anatomy relevant to percutaneous femoral arterial and venous catheterization
• Most common cause of paroxysmal SVT in the young adult
• Occurs over a small reentrant circuit located near the AV node
• The circuit consists of a fast and slow pathway connected by a common top and bottom pathway
This is common in coronary patients and is caused by increased vagal tone and usually eventually disappears with no problems
Mobitz II the PR is constant but with occasional dropped beats. This is a more serious arrhythmia because the injury is probably in fast conducting tissue below the His bundle which is not under vagal control.
What is this?
Mobitz I (Wenckebach) the PR progressively lengthens with one P wave for every QRS until a beat is dropped. Usually the block is above His bundle.
Slow ventricular rate Usually treated with pacemaker May be temporary or intermittent. Can be induced by drugs that cause increased vagotonia
WPW: Normally conducting cardiac muscle bridges the gap between atria and ventricles.
If accessory pathway has short antegrade refractory period, can have serious arrhythmias, especially with atrial fibrillation
Fig 3
Normal sinus rhythm Sinus tachycardia Sinus bradycardia
＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋ －－－－－－－－－－－－－－－
Torsades de Pointes
Rate in beats/min = 60/interval between two beats in seconds A handy shortcut is: