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Posts Tagged ‘aivr’

Reperfusion arrhythmia was described originally  in the thrombolytic era .

It can be any of the the following .

  • AIVR(Accelerated Idio Ventricular rhythm)
  • Sinus bradycardia (In Infero posterior MI )
  •  VF can occur as  Re-perfusion  arrhythmia.

Does these arrhythmia occur following primary PCI ?

It should  isn’t ? 

In fact it  must be  more pronounced  as we  believe PCI is far superior modality for reperfusion !

Busy Interventional  cardiologists  of the current era  either do not  look for it or fail to document it . These arrhythmias occurs only  with early Primary PCI (Say less than 2-3 hours) .If re-perfusion arrhythmias are  really less common with primary PCI , are we missing some thing ?

 

 

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Cardiac arrhythmias by nature connote a serious implication ,especially  so  with ventricular ones. Here is an  arrhythmia which arise from the ventricle by excessive automaticity  ,   fires independently  ,   still  very   benign compared  to others ventricular arrhythmias.

Why AIVR is a stable arrhytmia ?

Primarily due to its low rate.

Since  it is a  reperfusion arrhythmia the outcome is good.

Mechanism

It is not due to reentry , it is thought to be due to enhanced  automaticity  without pathological  intra-myocytic  calcium spikes  (Like true VT )

Absence in surface  ECG does not mean it is not existent.  In-fact there  is some  evidence to call this arrhythmia as a form of ventricular parasystole.

Focus of arrhythmia

Since it is a reperfusion arrhythmia it has to arise somewhere from  re-perfused myocardium.

The fact that  it  can occur in both RCA and LCA reperfusion  indicate the focus can be  in any of the ventricle .

Usually it follows the reciprocal rule of bundle branch block  pattern  (RBBB in LV focus LBBB in RV focus.)

Septal AIVR  can have either RBBB or LBB morphology.   Usually  left axis is noted .

How to differentiate it from  non sustained VT ?

  • Ventricular rate in AIVR should be between 60 -110 .(Note -The inherent ventricular rate is 35/mt .There is three fold acceleration )
  • Basic idoventricular rhythm is about 35.  Three times accelerated
  • Characteristically   AIVR  starts with an escape beat rather than an  ectopic beat .

AIVR  is common  in  RCA or   LCA reperfusion ?

It is supposed to be more common in infero-posterior MI  as sinus slowing is an important predisposing factor  for releasing   the idio ventricular rhythm.

AIVR after primary PCI

Is not reported much as  current interventional  cardiologists  do not bother much to watch about this arrhytmias

Other causes for AIVR

  • Myocarditis.
  • Digoxin toxicity

Management

(The commonest issue with AIVR  could be    . . . Nurses  /Fresh interns may mistake it as VT and  pressing the false alarm ! )

  • Rarely  requires treatment .
  • Atropine ,Isoprenaline to increase sinus rate.

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Thrombolytic therapy ,  has been  the specific treatment  for STEMI for  many decades. Primary PCI*  is  shown to be  superior  than  thrombolysis  if   performed   early  by an experienced  team in a dedicated facility. (*Conditions apply). It is estimated ,   currently only a  a fraction  STEMI  population get primary PCI (<5%) in ideal conditions . Another fraction , get  primary PCI by inexperienced cardiologists  in low volume centres.

So , thrombolysis   remains, and  would continue to remain ,   the    primary  mode of therapy for STEMI  in the  present and near  future !

How do you assess the successful  thrombolysis ?

It should be recognised ,  there is a fundametal flaw in this  question !

The aim of thrombolytic therapy is  not  to   lyse  the thrombus  , but also  to restore the coronary blood flow to the  myocardium – also called reperfusion . One may wonder , why the term ,  thrombolysis  should ‘t be  used interchangeably with reperfusion. 

A successful thrombolysis  never guarantees  a good reperfusion , for the simple reason ,  distal blood flow in an  obstructed coronary artery  is dependent on ,  many factors  other than relief of obstruction.

Apart from the potency of drug,     other   important factors  that determine  successful  lysis &  reperfusion are  . . .

  • Timing of opening of artery , if the thrombolysis is delayed  ,  the distal myocardium is dead , and   it won’t allow blood flow to enter the mycardium.
  • Microvascular integrity is as vital as epicardial vessels.
  • Distal microvascualture  plugging by the thrombotic debri . This is called”no reflow “

So , we should  primarily assess myocardial reperfusion rather than epicardial thrombolyis ! following thrombolysis .

What are the parameters available to assess successful reperfusion /thrombolyis?

  1. Clinical : Relief from chest  pain. Angina relief  , though subjective is an indication for adequate reperfusion of ischemic myocardium.
  2. ECG-ST segment regression > 50%
  3. Cardiac enzymes: Early flushing of  intra myocytic CPK into systemic circulation and hence early peaking of CPK MB (<1ohours instead of 24h)
  4. Reperfusion arrhythmias(AIVR-Less specific) .Primary VF is now thought to be reperfusion related.
  5. Infract related artery(IRA) patency by coronary angiogram
  6. Distal TIMI flow/ myocardial blush score/ TIMI frame count

ECG ST regression ,  is a direct indicator  myocardial reperfusion   as the ST segment shifts  towards baseline ,  implies  of infarct current of injury . ST regression almost always correlate with good  recovery of LV function  in STEMI .

IRA patency , is an epicardial index , it  does not give information about myocardial blood flow . But ,  a good  distal TIMI flow generally indicates good reperfusion.This  again ,  is  not a fool proof  index,  as even many of the TIMI 3 flow patients  have severely damaged myocardium by echocardiography .

Final message

For the above reasons, one should always  make a distinction between successful lysis and successful reperfusion . Surprisingly ,  ECG  is  the gold standard for assessing successful reperfusion of myocardium ,  while CAG tell us  about epicardial patency and possibly reperfusion also.

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