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Monday, April 26, 2021

Is it safe to do MRI in pacemaker patients with abandoned leads?

 Is it safe to perform an MR in a Pacemaker patient who has one or more abandoned leads? It seems that the conventional wisdom has been that it is not safe.

This article from RD Schaller et al (1) at the University of Pennsylvania  provides reassuring data. They present data on 139 patients in whom 200 MRs were performed without serious events. There were 5 instances of transient decrease in lead sensing and one patient complained of subjective sternal heating.

There no changes in battery voltage,or changes in pacing rate. Quoting the authors:

"The growing aggregate of data questions the absolute contraindication for MRI in patients with abandoned CIED leads." The authors also point out that CMS will not reimburse such cases.


(1) Schaller,RD et al, Magnetic resonance imaging in patients with cardiac implantable electronic devices with abandoned leads. JAMA Cardiol. published online Feb 17, 2021. doi:10/1001/jamacardiol.2020.7572

Friday, April 23, 2021

Another battery related recall for Medtronic implantable electronic devices

 

Has Medtronic had more battery related problems than other pacemaker manufacturers or does it just seem that way because of the number of recalls and battery life estimation issues reported in the last 2 -3 years and the fact that Medtronic makes more units than any other company? Medtronic is not alone. both Guidant and St. Jude have had major recalls .

Premature battery failure lead to St Jude's recall of ICDs and CRT-D units involving over 300 thousand world wide with 250000 in the US.Reports indicate that St. Jude knew of the problem for years before the recall. One death was reported in 2014 and a second death in 2016 before the October 2016 recall was issued.St Jude was purchased by Abbott.

A similar narrative can be told about Guidant who became aware of a shorting issue in their Prize II IC which did not allow the unit to deliver a shock while also destroying the  shocking system . Guidant informed the FDA and fixed the problem but did not warn physicians nor patients and continued to sell some units that had not been modified.The Prize was introduced into the market in 2000,  the flaw discovered in 2003 but it was not until  2005 that the company disclosed the problem. Finally in  October 2013 Boston Scientific who had purchased  Guidant pleaded guilty to a false claims act litigation and agreed to pay 296 million dollar fine. 

There were problems with  Medtronic CIED programmers in units made between October 2018 and January 2019 that resulted in erroneous estimate of battery life.These were ultimately corrected and in the end seemed to be really more of an anxiety producing nuisance than a threat. 

Also in 2019 there were three reports of pacemaker batteries being completely drained resulting in one death.This problems involved five different Medtronic models and 131000 units and involved a potential capacitor damage. This situation was troublesome to both EP cardiologists and the patients as there was no way to determine which specific units were likely to fail and pacemaker replacement is not a risk free minor procedure. Having a complicated device under your chest wall skin is anxiety producing enough without the added worry that the type unit you have had been known to suddenly fail. It seems to be a recurrent situation with CIED recalls that there is no way to determine if a particular unit within a class of units subject to the recall is in fact one that is doomed to fail.

On 2/3/2021 Medtronic send an "Urgent Medical Device Correction" letter to all affected physicians.  On 4/12/2021 The FDA announced a recall of about 240,00 Medtronic CIEDS.These are seven models of  CRT-ICDs and pacemaker ICDs. see here for link  This is a class I recall which means a potential risk for serious  injury or  death.

When a Medtronic pacemaker reaches a certain predetermined battery life remaining signal  the device is said to go to a RRT  setting or condition (Recommended replacement time) which sets a 3 month clock ticking before it goes to the next condition which is called ERT (elective replacement time).This condition, which I understand is unique to Medtronic PMs involves a Mode switch  to a VVI mode at a heart rate of 65.

Some devices involved in this latest recall may move from the RRT warning to full battery depletion in as little as 24 hours.There have been over 400 complaints with these devices and 18 "injuries" also reported. Generally PMS do not have a system feature that notifies patient or physician when RRT is reached. I will not know if my PM has reached RRT until a remote  ( or office ) interrogation designates that.(I have a five year old Medtronic model "Consulta"

 Questions come to mind-

Has Medtronic contacted the approximate quarter million patients who have these units or does the letter send to the physicians put the onus on the docs to spread the word?

Does the typical PM clinic have computerized records of which PM each of their patients have? 

A 2017 report from office of the inspector general estimated that 1.5 billion dollars had been paid by Medicare for replacement of 7 different models of CIED in 73,000 patients during the time period 2005-2013.According to the report manufacturers do not typically pay for replacement costs, 

Medtronic has also had recalls recently for its HVAD units (see here) and its blood pump (see here)


Wednesday, April 14, 2021

Complications from Left Bundle Branch area pacing

 Chen et al (1) report their experience in 612 LBBA implantations from 2018 to  2020 .Mean time of followup was 12.5 months.

Complication rate was low. and consisted of:

2 post operative septal perforations,2 post operative lead displacements ,4 intra operative septal injuries and 2 intra operative lead fractures,none of which had serious consequences.


1) Chen, X. Procedures-related complications of Left Bundle pacing: A single center experience. 

frontiers of Cardiovascular Medicine,24 March 2021. Full text is available on line. 

Monday, April 12, 2021

What is the mechanism of left axis deviation in some cases of Left bundle branch block?

 Dr. Saer Abu-Alrub et al (1) offer one explanation for  the occurrence of left axis deviation (LAD) in some cases of left bundle branch block (LBBB).

Twenty nine patients with non-ischemic cardiomyopathy were studied with non invasive cardiac mapping, CT and MR imaging .Sixteen had a normal QRS axis while 13 had LAD .The LAD group demonstrated delayed activation of the basal anterolateral region.The LAD group demonstrated an apex to base activation pattern versus a circumferential pattern observed in the normal axis group.

 Imaging studies demonstrated no differences in cardiac structure between the two groups so the investigators concluded that LBBB with LAD was a "purely electrical phenomenon".

Some LBBB patients with LAD  treated with CRT ( either by BIV or conduction system pacing)have normalization of the QRS duration and of the electrical axis while others have only the QRS normalized with the left axis unchanged. I have been unable to find any explanation of that. 



1) Abu-Alrub,S et al Left axis deviation in patients with non ischemic heart failure and left bundle branch block is a purely electrical phenomenon. Heart Rhythm, 2021 April  33831543

Do some patients with idiopathic left bundle branch block have an underlying cardiomyopathy?

Janek Salatzki and co workers (1) present evidence that there may more at work in idiopathic LBBB (ILBBB) than simply dysynchrony. It is generally accepted than LBBB alone can cause heart failure (HF) and myocardial remodeling. Salazki present data using an innovative technique,determination of septal flash volume, which they believe suggests that a contractile impairment is a necessary condition for remodeling while dysynchrony alone may induce heart failure.

The authors state that another explanation for their data is that the LBBB group with remodeling were simply patients who had the LBBB longer. The retrospective nature of their data does not enable them to exclude that alternative.

The first description of ILBBB causing heart failure was in 2005 and one of the speculations at that time was that there was an underlying cardiomyopathy , i.e. it just was not simply the dysynchrony operative in causing HF to develop but a disease process affecting both muscle and conduction fibers.The various case series demonstrating a favorable and often super respond in lone LBBB patients treated with either  BiV or conduction system pacing  suggests that desynchrony is the dominant problem.  

1)Salatski,J et al Presence of contractile impairment appears crucial for structural remodeling in idiopathic left bundle branch block Journal of cardiovascular resonance.2021 april 23 

2). Blanc J et al. Evaluation of left bundle branch block as a reversible cause of non-ischemic dilated cardiomyopathy with severe heart failure. A new concept of left ventricular dyssynchrony-induced cardiomyopathy. Europace 2005;7,604

Friday, April 09, 2021

Left bundle branch area pacing as alternative for bi-ventricular pacing for refractory heart failure

 Should cardiac conduction system pacing replace bi-ventricular pacing for patients with refractory heart failure (HF)? The two forms of conduction system pacing are His bundle pacing and left bundle branch area pacing.

Vijayaraman et al(1)have  published the results of a retrospective multi center study to asses the feasibility and outcomes of left bundle branch area pacing (LBBAP) in patients as an alternative to bi-ventricular  pacing (Bi-V). See herehttps://www.jacc.org/doi/pdf/10.1016/j.jacep.2020.08.015

LBBAP pacing was attempted in 325 patients and was successful in 277 or 85%.LBBAP resulted in significant shortening of the QRS,clinical and echocardiographic improvement, and was achieved with low thresholds and adequately high R waves. In short, LBBAP seemed feasible and safe. No mention was made in the abstract regarding septal wall perforation an event that had been reported in some earlier case series. 

Among clinical indications for pacemaker implantation none equal the randomized clinic trial data supporting CRT using BIV.

There are observational data supporting the value of both His Bundle pacing and now LBBAP as an alternative to Bi V pacing. I think  a large RCT would be necessary to demonstrate superiority or more likely non-inferiority  of cardiac conduction pacing versus BiV.Where would funding for that be found?



1)Vijayaraman,p et al Left bundle branch area pacing for cardiac resynchronization therapy:Results from  the International LBBAP collaborative study. JACC Clin EP archives, vol 7 no. 2 135-137. 

  

Wednesday, April 07, 2021

Implantation of both His Lead and LBBA lead in atrial fibrillation patients

 In the early days of His bundle pacing (HBP) there was a issue of whether or not a backup lead should also be implanted.This controversy has apparently not been completely resolved and may have regained some steam as reports have appeared indicating  that some not insignificant number of His  leads develop high thresholds even though the initial threshold was appropriate.

Yand Ye et al (1) describe an interesting variation of using a backup in conjunction with a His Lead.They studied 16  AF patients who were pacemaker dependent in whom they attempted to place both a His lead and a left bundle branch area lead.(LBBA).The His lead was the primary pacing lead and the LBBA lead was considered the backup lead. thirteen of the sixteen were successfully implanted. Although the results section of the paper is somewhat unclear apparently at least one patient had a increase in the capture threshold leading to switching to the LBBA lead. During the six month follow-up there were no lead dislodgments or ventricular perforations.There have been a few reports of late perforations of the  LBBA pacing lead.


The authors conclude that the technique is doable and safe and may offer an approach at least for PM dependent patients with AF.In this group of patients the rivalry between HBP and LBBA pacing could be avoided.Maybe not a either or but a both.


1) Yand Le, Feasibility and safety of both His Bundle Pacing and left bundle branch area pacing in atrial fibrillation patients: intermediate term follow-up.Journal of interventional cardiac electrophysiology. 2021 March 15 33723691






Tuesday, April 06, 2021

Does location of His lead (above or below the tricuspid valve) matter?

 A study of fifty patients by Y. Hu et al (1)  indicates that it does matter. Two problems with His pacing are higher capture threshold voltage are needed and lower R waves. Hu's data indicate that in the 25 patients who were implanted below the TV there were lower ventricular capture thresholds and higher R waves.Echo studies showed no tricuspid regurgitation.

 Somewhat different results were reported by Tang et al (2) in that they found capture voltage to be no different in the atrial leads  compared to the ventricular lead placement in a study of 13 atrial placed His leads and 16 ventricular placed leads. However, they also found that the R wave sensing values were higher in the ventricular lead group with values at implant being 1.87 V for the atrial lead and 4.53 V for the ventricular group. 


Also it is generally thought  in cases of AV block that a sub valvular implantation may be preferred  and that non-selective His pacing may to preferable to selective because it can be its own back up. 


 1)Hu,Y Electrical characteristics of pacing different portion of the His bundle in bradycardia patients 

Europace,2020 December 26, supplement ii 27

2)Tang, C Effect of implantation site of the His bundle pacing leads on pacing parameters a single center experience BMC Cardiovascular disorders. 2021 Feb 24 2021 (1) 112, 

His Bundle pacing can normalize ventricular activation but can it also actually reconstitute native intrinsic conduction ?

His Bundle pacing  (HBP) has been known for years to be capable of normalizing bundle branch blocks. By normalizing I mean that the QRS while the patient is being paced becomes normal with Selective HBP and nearly so with non selective HBP. By reconstitution I mean that the QRS remains normal after HBP is turned off.  Reconstitution  is what authors of 2 case reports document in a article in Heart Rhythm Case Reports.

Dr FM Ezzeddine at al  (1) report two case in which patients with long standing conduction defects were implanted with His leads and after several months of treatment with His bundle CRT  were noted on routine testing  to have resolution of their conduction defects.One patient who had an av block and LBBB had resolution of the AV block while the LBBB continued and the second patient had restoration of normal ventricular conduction no longer having an LBBB pattern. Both patients experienced a significant resolution of their heart failure symptoms when His bundle paced CRT was begun.

Quoting the authors with my underlining.

"His Bundle pacing can restore native intrinsic conduction in some cases after years of chronic conduction block". ..    this demonstrates new theoretical benefits of HBP , the ability to promote conduction down the native pathways that were previously non-conducting." 

 What I  believe  the authors are proposing is that  His bundle pacing had somehow brought about  electrical remodeling  leading to a condition in which pacing was no longer needed to bypass or override whatever specific type of conduction defect the patient had experienced. They consider mechanisms such as Wedensky facilitation which refers to an impulse arriving at a blocked zone and increasing the excitability of tissue beyond the block. Other electrophysiologic speculations are offered.

There have reports of exercise induced LBBB and intermittent rate related LBBB but the authors believe these are the first reports of long standing conduction defects that recovered native conduction following continuous His bundle pacing.

On page 412 of Serge Barold's illustrated guide to pacemakers and resynchronizatio (2)n  the authors suggest there is value to periodically "expose " the underlying spontaneous EKG. This was said in the context of followup on bi-ventricular pacing but perhaps Ezzeddine's paper offers a reason to do that for patients with LBBB who are being His bundle paced.   


 

1) Ezzeddine, FM et al Reconstitution of native intrinsic conduction in patients with chronic conduction block with His bundle pacing. Heart Rhythm Case Reports.2021 1-5,  https;//doi/org/10.1016/j.hrcr,2021.03.006

note: The same cases were presented as a poster, at the JACC meting march 20,2018 by Dr. Ezzeddine

2) Cardiac Pacemakers and Resynchronization , step by step  An Illustrated guide. Second Edition,

Bakrold,SS, Stroobandt, RX adn Sinnaeve, AF