MASA

EPSの引き出し、知識を広げたいポンコツCE 。「EP大学」の動画などで大好きなEPSを勉強中です。 日々感謝！あと、バイクはcb223sに乗ってます。 I'm clinical engineer working at japan OSAKA and very interesting in EPS for PSVT.

[CardiovascularCorner @TrackYourHeart]

ECG Breakdown

Clinical scenario:
An 81-year-old woman presents with palpitations.

Step 1: Rhythm
🔺Regular narrow-complex tachycardia.
🔺Ventricular rate approx 160–180 bpm.
🔺QRS complexes are narrow (<120 ms).
This confirms a supraventricular tachycardia (SVT).

Step 2: Look for P waves
🔹No obvious sinus P waves preceding the QRS complexes.
🔹In lead V1, there is a small positive deflection at the terminal portion of the QRS complex (pseudo R′ wave).
This represents retrograde atrial activation.

Step 3: Key diagnostic clue
⚪The arrows in the image below highlight the pseudo R′ waves in V1.

During the tachycardia:
- Pseudo R′ is present.

After spontaneous conversion to sinus rhythm:
- The pseudo R′ disappears.
Normal sinus P waves become visible.

This strongly indicates that the atria are being activated retrogradely from the AV node rather than from the sinus node.

Step 4: Mechanism

Typical AV nodal re-entrant tachycardia (AVNRT):

Atrial impulse travels:
- Antegrade down the slow pathway
- Retrograde up the fast pathway
This creates a re-entry circuit within or near the AV node.

As a result:
◻️ Atria and ventricles are activated almost simultaneously.
◻️Retrograde P waves become buried within the QRS complex.
◻️In V1 they appear as a pseudo R′ wave.

Final Diagnosis:
Typical AV Nodal Re-entrant Tachycardia (AVNRT)
(A form of Paroxysmal Supraventricular Tachycardia, PSVT)

[MASA @MASA02460147]

@Paul_Wischmeyer VA ECMO🤔
To prevent ischemia in the leg, a bypass is performed from the ECMO blood supply side to the femoral artery (7fr sheath).
I can see the rSO2 probe on the lower leg.

[MASA @MASA02460147]

@ECGEPSCADEVICE 美しいです、先生😍
RVbaseからペーシングしてるんですね、確かにAVNにとってはその方がHAを評価しやすそうです✨
ペーシングと頻拍中のHAを比較して（ΔHA）ペーシング中のHA時間が15ms以上長いとLCPがあると思われます。なので右のtraceの方ですね🥹
左はslow-fastで右はslow-slowかもですね🤔

[MASA @MASA02460147]

@jiro_ecg 50bpm以下。RAD、Ⅰ.aVLはabQかも。キャリバー倍、恐らくsinus rhythm、繋がっているのかCHBか判別できませんでした。（sinusならば）morris index +
上肢つけ間違い疑いましたがⅠ誘導P波は恐らく陽性でありV1とaVRも似ておりつけ間違えではなさそうか。
肺が悪い？あとは漏斗胸はどうでしょうか🙇🏻

[Heart Rhythm O2 @HRS_O2Journal]

Induction indices during ventricular pacing as an alternative diagnostic tool in supraventricular tachycardias, by @OsakanogishiM, @MasatoOkada1105, and colleagues
#EPeeps
https://t.co/vJcuhtLzU8

[MASA @MASA02460147]

@ECGEPSCADEVICE 貴重な心電図をありがとうございます🙇🏻
恐らく後中隔やとはおもうんですが、移行帯が早そうですね🤔
僧帽弁輪後中隔の可能性もあり、もしEPできるならRVAからの「SAと頻拍中のVAの差」、もしくは頻拍中にRVAOPが出来れば「SA-VA」をチェックして40msを越えれば左アプローチを考慮でしょうか🤔

[MASA @MASA02460147]

@syamkumarmd I'm sorry. I've realized my mistake. I will reconsider it carefully🙇🏻

[Syamkumar @syamkumarmd]

Slightly higher level EGM for trainees. What is being done here? #EGM #EPeeps #AblateVT

[MASA @MASA02460147]

@syamkumarmd This is very informative for me🙇🏻
Thank you very much！

[MASA @MASA02460147]

@syamkumarmd Thank you so much. I was wrong🙇🏻
The insertion should be almost simultaneous with the QRS timing.
I understand the timing of the refractory period of HIS to be "late," is that correct?

[MASA @MASA02460147]

@syamkumarmd The early PAC insertion immediate hisresets,extending the VA. There is no conventional VA linking. Furthermore, the AA for the two beats surrounding the PAC is not reset, supporting AT. However, there is a possibility of cancellation due to VA decri, so I'll to try other methods.

[MASA @MASA02460147]

@ECGEPSCADEVICE 大変勉強になります🥹
ありがとうございます🙇🏻🙇🏻🙇🏻

[MASA @MASA02460147]

@ECGEPSCADEVICE めちゃくちゃ勉強になります🙇🏻
読みたいです🥹
見かけ上凄く短いAHですが、AOPにより順伝導はSPであることがわかります🙇🏻
先生、見当違いなこと承知で聞きたいのですが、VOP時はVAHレスポンスでATをr/oできないでしょうか🤔
その二択ならLCPが長い、もしくは伝導遅延しているs/f AVNRTだと思いました🥹

[MASA @MASA02460147]

@Teebi_MD @Amhar_47 VES during tachy（reset＋、sequence same）
VAV responce（AT r/o）
PPI-TCL＝Approximately 60ms
SA-VA →short

I suspect this is ORT with left bundle branch block (aberrancy), but I'd like to see an evaluation of the HV interval and the response to atrial pacing🤔

[MASA @MASA02460147]

@Teebi_MD @Amhar_47 VES during tachy（reset＋、sequence same）
VAV responce（AT r/o）
PPI-TCL＝Approximately 60ms
SA-VA →short

I suspect this is ORT with left bundle branch block (aberrancy), but I'd like to see an evaluation of the HV interval and the response to atrial pacing🤔

[Ahmed Teebi, MD MPH MSc(Ox)🗝️ @Teebi_MD]

🧵More #EGMDecoded! Classic one for EP fellows. What’s the interpretation for this maneuver during EP study? What’s the mechanism of SVT?! #Epeeps

[まめたろう,MD, PhD🫛EP Univ. @mameeps]

【gap現象】
期外刺激に対し一定期間伝導途絶する(gap)が、更に連結期を縮めると伝導が再開する現象✍️
連結期が短くなることで上流で伝導遅延発生→伝導途絶していた"下流視点のinput"で考えると、連結期が長くなるため。
Initial block/Proximal delay部位でType I～Vに分類🤔https://t.co/RkMhKrbtHa

[Syamkumar @syamkumarmd]

It is indeed the Retrograde Type 2 Gap Phenomenon. His bundle potential seen after the V suggests retrograde RBBB, allowing AV nodal conduction to recover.

[MASA @MASA02460147]

@syamkumarmd 270→retro slow（or retro2）＋ante fast ventricular responce
260→retro fast return

I suspect that the prolongation of the 「stim-local V 」interval did not shorten the VV interval, and it reverted to going through fast again (GAP phenomenon)🤔