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