Why many Ischemic VTs are usually not abolished by revascularization ?

Why many Ischemic VTs are usually not abolished by revascularization ?

August 19, 2024 by dr s venkatesan

Who mentioned this non-sensible assertion? ( I assume ,this might be the primary response from many cardiologists !) In case you really feel the identical, then this put up may not be for you.

Relationship between Ischemia and arrhythmia

Whereas the connection between Ischemia and VT is basically advanced, the time period “Ischemic VT” itself provides extra twists. Its all about timing, depth of Ischemia , related elements and eventually the baseline arrhythmic danger that features the thriller defects in myocyte hole junctions and ion channels.

Following are among the observations.

Major VT

That is the true Ischemic VT. Even right here, it’s the related elements, like hypoxia or acidosis are the triggers which after all are resultant of Ischemia. There’s a downside right here too ,even crucial Ischemia with excessive grade unstable angina not often set off a VT however STEMI appears to have the unique rights to set off it , by its means to provide acute transmural ischemia . (Notice: Whether or not major VT happens earlier than or after myocardial necrosis shouldn’t be clear) There are some crucial proof, that proves ,the susceptibility to VT at instances of Ischemia is within the genetic make of ion channels as identified by well-known French electrophysiologist Haïssaguerre. (NEJM 2008)

Put up Infarct VT : (24 hrs to 2 weeks ,an empirical standards we use)

This may be known as as Ischemic, nonetheless we ‘wouldn’t know whether or not the arrhythmia is originating from lifeless or reside tissue. It may even be mixed Ischemic-Scar VT

Late Ischemic VT

These are the everyday scar – substrate -mediated ,micro/macro reentry VT .The strip of tissue on the border zones of battle (between viability and non viability is at all times stressed (Gaza strip of VT?) That is not often amenable to revascularization, until some one is ready make that space 0% Ischemic , which is a extremely inconceivable situation. The alternate possibility is diagonally reverse .EP guys are empowered with a lethal answer, and approved to shoot down focus (or isolate) as a substitute of the futility of revascularisation. (Please notice, this doesn’t work and shouldn’t be tried in early ischemic VT, although few case experiences of RF ablations throughout VT storm li- Juan Qu et al AMJS 2924 )

Closing message

The connection between Ischemia and VT is poorly understood, (somewhat than to say advanced.) It’s true ,acute Ischemic VTs has extra nearer relation with Ischemia, usually settles down with immediate revascularization.

In power VT , taking pictures down the ischemic focus by ablation its extra more likely to extinguish the arrhythmia ,somewhat than revascularization. It is because partial revascularization irritates the viable myocardium and preserve the ischemic focus lively. ( Class C proof) ICD although a revolutionary expertise to stop a SCD in these circumstance it makes a poor selection to scale back the arrhythmic burden .At greatest , it’s only a again up machine to sort out the escaped VTs despite RF ablation and medicines.

Reference

1.Haïssaguerre M, Hocini M, Cheniti G, Duchateau J, Structural Alterations Underlying a Subset of Unexplained Sudden Cardiac Loss of life. Circ Arrhythm Electrophysiol. 2018 Jul;11(7):e006120. doi: 10.1161/CIRCEP.117.006120. PMID: 30002064; PMCID: PMC7661047.