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Archive for the ‘Pace maker Tips and tricks’ Category

Pacemaker implantation is one of the few high impact interventions done by cardiologists.Traditionally , RV apex was paced for many decades with tined or screwing leads. Serious concern was raised in recent years about the ideal site of pacemaker lead position. .Today, some argue  pacing RV from RV apex is a electro-physiological crime (Of-course it appears  more of hyped up fear ! )

What is the concern with RV apical pacing  ?

RV apical pacing is  unphysiological .To mimic physiology we have to move the lead as  cranial as possible within RV. (*Obviously  pacing anywhere in RV is non-physiological .Best would be atrial pacing . This is possible only  in sinus node dysfunction with Intact AV conduction.) Hence RVOT and mid septal pacing was proposed and practiced as a relatively  more physiological site as the spike could capture the natural conduction system early and ventricle is activated from above down.

How to localise the RV lead in mid septum ?

Inter ventricular septum , hardly occupies an area of 5/5 sq cm  with a  complex structure , shape and alignment with RV and LV cavity .In pathological states it can further get distorted. To catch it’s profile in fluoroscopy and imagine the plane requires a mind of “cardiac architect”.So, to locate the  IVS various views are suggested. Currently LAO 40 is typically  used for fixing  mid septal position. In midseptal position ECG is expected to show small q  in lead 1 and AVL. QRS axis will be more left .We seemed to agree with this.

rv pacing mid septal postion rvot rv apical
Image courtesy: Pavel Osmancik Circulation: Arrhythmia and Electrophysiology. 2013; 6: 719-725 Fluoroscopic examples of 2 patients. One with correct lead placement in the septum (A–C) and the other with the lead placed in the anterior wall (D–F). See the similarity of the left anterior oblique 40 view, the difference of the right anterior oblique 30 and the location of the lead on computed tomography image.

And suddenly  this paper  from  the picturesque  city of  Prague , Czechoslovakia throws a stunner.

What we have been thinking as  mid septal pacing with LAO protocol turns out to be   anterior RV pacing in 60% of times.The study showed LA0 40 view  failed to differentiate anterior RV pacing from mid septal pacing .CT scan correlates have documented this . Further ,we have never given a thought to the wayward trabecuale coming across mid septal zone. It has happened time and again (Atleast i have witnessed) the lead would  just fall short of IVS and get screwed in the trabeculae  with high risk for dislodgement . RAO 30 view  consistently separates the mid septal lead from anterior  RV position.It is suggested a carefully done per-procedure echo would also be useful in locating the lead tip .

What hemodynamic implication of mid vs RV anterior pacing ?

Could be significant . No reliable data available. It s tempting to think the hemodynamic inadequacies of an improperly placed mid septal RV pacing may not be different from a conventional RV apex pacing .

Final message

The complex shape of RV and IVS in  fluoroscopy can fool us. If you really want to pace the mid septum, please ensure with multiple views and confirm with RAO 30  . Also remember echocardiography is not a forbidden tool for localising pacemaker lead.

Reference

1.The Insufficiency of Left Anterior Oblique and the Usefulness of Right Anterior Oblique Projection for Correct Localization of a Computed Tomography–Verified Right Ventricular Lead Into the Midseptum Pavel Osmancik, Petr Stros, Dalibor Heart 2013; 6: 719-725

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We have been taught right from first year cardiology residency  how to trouble shoot a pacemaker .It has been a real complex thing for us. Now looking  back ,all the troubles we took to understand seems to be redundant.Here is a summary of my thought process on the issue. It can be approached  with reference  to time, symptoms and ECG features.  With due respects to all those brainy hardworking   EP experts  , I have taken few academic liberties!

pacemaker trouble shooting

Timing

  • Within 24 hours -100% technical or procedural Issues , like lead dislodgement/Screws and nuts.
  • Within 1-2 week – Again technical , Pocket issues , Infections.
  • Within 6 months – Benign pacemaker syndrome ,Threshold settings, Scars
  • After  first year – Generally Issues are rare , Lead issues , Associate disease progression.
  • Beyond 8-10  years /Near end of life – 95% Energy depletion leads issues .( Please note , pacemakers do not stop all of a sudden it has a intrinsic end of life indicators .We have to look for it. May be ,we can expect a  warning siren in the future ? )

Symptoms

  • Vague dizziness – Pacemaker syndrome ? Anxiety ?
  • Near syncope – Show some concern (For many , Impending true syncope is a non existent entity )
  • True syncope  – Real emergency*

* Syncope can be unrelated to pacemaker but always consider  them electrical  unless proved otherwise . Few patients  may continue to have significant symptoms  in-spite of   normal pacemaker parameters. This would  mean , the original symptom for which  pacemaker was put is not related to the Brady-arrhythmia .It could   suggest alternative hemodynamic explanation  like vaso-depressive component of vagal syncope ,autonomic dysfunction , orthostatic intolerance or  a coexisting neurological /systemic condition.

**Never forget syncope is not an exclusive symptom of bradycardia .A new onset  tachycardia  , which is either a part of  brady- tachy syndrome or separate arrhythmia can continue to provoke the symptom.

Gross ECG findings

Bradycardia /Often implies back to original rhythm –  Indicates real trouble . Since ,in a paced patient HR cannot be less than programmed rate of 70.

Tachycardia -No spike.( Not to worry ?) A common  situation if the original indication was  sinus node dysfunction . Many of them are  in own sinus rhythm or AF . Just ensure spikes reappear when the rate falls below 70 . If the rate never goes down , what to do ? Try a carotid massage or observe a nocturnal ECG  or call analyst and increase the rate to document pacing . (In DDD mode we have a rare PM mediated re-entrant tachycardia , which is mainly used to grill cardiology fellows in their board exams with all those PVARP stuff !)

Simple pauses – Any pause more than the pacing interval is a definite concern .

Spikes more than QRS  – Indicate capture failure.

No spikes (Can be so benign  to ultimate danger )

  • No spikes , but  excellent own rhythm – Good  functional  SA node
  • Regular  spikes ,but intermittent own rhythm or only random spikes with good own rhythm – Needs bedside hairsplitting and  EP assistance !
  • “No spikes -No Own rhythm” -Most dangerous .Sudden lead issues or hyper sensing .(Emergency  switch off  by magnet  application before inserting temporary pacing advised )

* Anatomical issues like lead dislodgement , fracture , compression ,  perforation are to be ruled out in every pateitn with intermittent capture or failure .This is done by combinations of imaging as well physiological assessment.Dislodgement must be visualized .The term micro dislodgement may not exist.

Other Investigations

  • X ray
  • Echo for any new structural lesion (RA,RV dilatation , TR RV clots or vegetation )
  • Holter
  • Event monitors ,Loop recorders.

Pacemaker analysis

  • Battery life ( Very important parameter .Usually around 10 -12 years.Unexpected early drain can occur.)
  • Threshold (Most failure to capture associated with high threshold Note :Threshold will be normal in battery depletion Acute threshold can increase marginally .Should be reasonable other wise battery will drain.New protocols like auto capture and managed pacing will help optimal threshold
  • Impedance – Normal in battery depletion , dislodgement and exit block,  Increased in lead fracture and loose screws.Decreased or lost in insulation failure.

Management

The principle of management are simple. Few logical questions ,

  • Is the pacemaker generator is alive and has has enough energy ?
  • Are the  leads okay ?
  • The problem is in the settings ? can it be rectifies by the programmer
  • Or should we replace the pacemaker ?

Technical jargon like  under sensing , over sensing or no sensing  , fusion beats , micro dis-lodgement  etc are important for  academic reasons . We may talk any thing , realistically , what  the ventricle want  is a non stop heart beat  every second or so !

Emergency

Bradycardia – Insert a temporary pacemaker /Call the analyst  /Inform the  electrophysiologist /Senior cardiologists /(Please realise ,  some fellows  can be better than the personnel mentioned above in tackling emergencies !)

Tachycardia : Native or machine induced ?

Native – Mostly safe ,  Ignore  or treat with drugs.

Machine induced :(very rare) Switch of the pacemaker . No off switch available as in a mobile phone ? *What to do ? if unclear about the  whereabouts  tachycardia origin . If hemodynamically unstable no harm in shocking .Nothing will happen .Call the EP  guys on hot line and decide.

Elective symptom guided.

  • Asymptomatic -Normal ECG : Reassure and send home.
  • Vague symptoms   -Do Holter and Observe
  • Syncope -Normal ECG needs extensive all system investigation.
  • Syncope -With pauses /Bradycardia /Asystole  – Ironically ,decision  making is easier. Temporary pacing is the  ultimate savior. Later , check the lead,  generator .One may need to change  either one or both of of them.

** While the above principles apply  for both single  and dual chamber pacemakers , the later doubles our thinking burden . While atrial tracking is a great technological advancement , what to  do with those sensed event can be really  tricky .The response of  ventricles and the AV intervals  can be tentative at times. Cross talks from unexpected atrial and ventricular arrhythmia can occur.  Further , mechanical atrial lead  issues are far  more common . When confronted with recurrent atrial lead related  problems , one  simple solution is  silently convert the mode to  single chamber VVI mode.

Final message

Pacemaker trouble shooting appears complex at the first look .It’s all common sense.Thinking with simple state of mind and  being clear about the intended  goal is vital. Electrical intricacies are tough to understand  but most situations do not require them. However ,If the initial indication was for complete heart block one has  to be very alert.

Principles of medicine argue us to make an exact diagnosis before treating . But,realise  this is rarely  possible or even desirable in emergency .Curiously , most pacemaker troubles can be solved successfully without making a proper trouble shoot !

If  we can summarize in one line  , a prompt emergency  back up temporary pacemaker insertion  is key to  management most of the serious  pacemaker related problems.It ,not only tackles the emergency ,  buys time till we decode the real problem . . .  if we wish to !

Related article.

Role of magnet application in pacemaker trouble shoot

 

 

 

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Inserting an ICD  for  DCM  may a be great therapeutic success  for the physician  as well as the patient . But there is one big truth hidden behind the statistical screen.

Following  study  provides dramatic data from Maanhiem in Germany in about 561 patients who had ICD .The long term patient outcome after appropriate shocks were much worse  than those without    shocks .This was more pronounced in Ischemic DCM .

appropriate and inappropriate shocks ICD

Source : Streitner et al ,University Medical Centre Mannheim, Mannheim, Germany PLoS One. 2013 May 10;8(5):e6391

The fact that these patients continue to throw VT , some thing is wrong in the cellular  milieu or a fresh scar / fibrosis / ischemia is progressing .Further , the VTs and the  subsequent  shocks  set in temporary  hemodynamic instability .We have evidence , EF can be depressed for days  worsening the long-term out come.

While it is easy  to blame it on natural course of DCM , there are  solid reasons to believe  , shock induced myocardial damage is definitely contributing to this  excess mortality.

One important  clinical tip is to screen  all  these so called Idiopathic DCM  patients  who  had appropriate shocks.  They should be monitored for fresh signs of any systemic illness  , like a  connective tissue disorder , chronic granulomatous lesions  like sarcoid etc .To our surprise  some specific  myocardial disease may unmask themselves in the natural history. Identifying them may offer a dramatic cure .

Final message

Some where along our EP mind-set  we are conditioned to think  , as along as there is an ICD in situ and it appropriately  shocks, every thing is bliss ! Blame it  on semantics . The  word “appropriate”  inappropriately  soothes  our nerves.

The fact of the mater is , every appropriate shock is a  grim reminder  that the heart  in question  is restless electrically and VT continue to emanate  from diseased  myocardium  . It could  mean either the LV   is destabilising  , or the original  disease  is   progressing  or a new disease  is evolving .

Mean while, paradoxically , inappropriate shocks give us a quixotic comfort , since the  heart is not really  throwing any dangerous arrhythmia, after all it is  the device related  false alarm   that  could be easily  reprogrammed!

Reference

ICD appropriate and inappropriate shocks

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Pacemaker lead implantation is basically a blind procedure .We are supposed to pace the RV apex . It is akin to anchor a ship in the sea bed. Screwing leads are preferred in permanent pacing  ,but tined leads have few unique advantages as well .

Can we combine the advantage of both ?

pacemaker lead in rv apex anchoring how to

It is believed displacements are more common with tined leads . May be yes . . . or  is it really so ?

It is not the tines  or screws that is going to  determine the early displacement , rather ,  it is the expertise , commitment and the time spent during the implantation that matters . I have witnessed equal number of  early lead dislodgement in both .

One issue often goes unreported is that , when screwing lead is used operator is subconsciously complacent.While cardiologists who implant  tined lead is more cautious , make sure it is well trapped in RV.

Screwing leads.

  • Screwing leads should not be positioned in the same place as tine leads.
  • This is because , RV apex is rich in trabeculae. Screws can enter one of the trabeculae or it may even enter  inter  trabecular  space. or poke  thin trabeculae which may  break in near future.(Realise ,how blind we are !)
  • Screwing  should be done in area where there is least  trabeculae  ideally in  lower end of septum. Since we do it blindly , we can’t be sure where exactly we have screwed .
  • Please note , pacing parameters are less  reliable than anatomy One may get surprisingly good pacing threshold even in trabecular pacing.
  • RV non apical pacing is possible only with screwing leads . However , the superiority of RVOT, para hisian pacing is yet to established in patients with normal LV function (Note  90 % of individuals who require PPM have normal LV function )

Tined leads

  • In contrary,tined leads are best placed where there is dense trabeculae.
  • It is natural entrapment.
  • The expertise of screwing  in a best place of RV is not required.
  • Whether screwing  predispose   to septal perforations in long term follow up is not known. Logic would suggest it may  !  (The Initial of few mm  of IVS tunneling  is done by us ! )
  • Diaphragmatic twtiching is more common with screwing leads.
  • Explantation  issues  is similar in both .

What does experienced cardiologists say ?

Cardiologists before the era of EPs were using  only tined leads  without any major hitch . I know electrophysiologists rarely use tined leads now . In our institute ,  with a  cumulative experience of over 3000  pacemakers  over 30 years( 99% are with tined leads ) , we  have no reason to believe they are vastly superior technique.

However there are few definite Indication for screwing lead

  • Abnormal RV anatomy
  • Loss of RV trabeculae
  • Marked Tricuspid regurgitation
  • Pulmonary hypertension
  • Second lead in RV
  • LTGV

* Note all atrial based pacing are screw based as atria lack trabeculae.

A suggestion

pacemaker lead in rv apex anchoring how to tined vs screwing lead   003

Final message

I would believe ,there is no major difference in both short and long term outcome between these two system of leads.Each has it’s own advantage.

After thought

Why can’t  we accrue  the benefits of both ? I think we have good scientific reason to request the pacemaker industry   to  design  a lead which  can have both tines and screws to  provide  double safety .Simple isn’t ?

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