WHY JUST ONE LEAD ?
When atrio-ventricular conduction is lost, unstable or too slow, restoring the physiologic relationship between the activity of the two chambers is the therapeutic goal. The pacemaker must detect the intrinsic atrial depolarization and pace the ventricle with the proper delay after each sensing event.
AVB with sinus rhythmand chronotropic competence >>> VDD or DDD pacing
If the pathology does not require atrial stimulation, the implantation of a single-pass AV lead is the most convenient solution. The lead is en-dowed with a ventricular dipole at the distal end and a “floating” proximal dipole, performing atrial sensing at a distance from the myocardium (single-lead VDD pacing).
A single-pass AV lead is the most convenient solution
Advantages of the single-pass AV lead vs. a DDD system/h4>
- Easier venous access and shorter implantationprocedure, as one introducer only is requested.
- Reduced risk of infection and thrombo-emboliccomplications, as less external material is pla-ced inside the body.
- Insulation loss due to friction of two leads lying in the same vein is avoided.
Advantages vs. a VVI system
- Re-establishment of atrio-ventricular synchronization and active diastolic filling.
- Natural chronotropic regulation.
- Improvement of functional performance and reduction of myocardial stress.
VDD SYSTEMS ARE NOT ALL THE SAME
Medico has been devoted to the development and optimization of single-lead VDD systems since the ‘80s, when this stimulation technique was introduced in the clinical practice, playing an impor-tant role in the diffusion of VDD pacing all around the world.
The specific commitment to VDD technology and the experience acquired with more than 100,000 implants, many of which with very long follow-up, make Medico an established leader in this field.
More than 100.000 implants
FLOATING SENSING WITH PHYMOS SINGLE-PASS LEADS
The main and exclusive feature of all single-pass lead models manufactured by Medico is the 30 mm wide atrial dipole, which has proved a superior tool in floating sensing.
Atrial dipole of 30 mm
When the floating dipole is found along the central axis of the atrium, at maximum distance from any wall, two electrodes spaced by 30 mm simultaneously record the negative and positive peaks of their unipolar electrograms, resulting in the best possible dif-ferential signal.
The atrial signal of Phymos single-pass leads is remarkably stable even in the most challenging conditions. This largely explains the clinical success well documented by several scientific publications.
LONG-TERM GLOBAL SAFETY
At 5 years follow-up, regular VDD pacing is maintained in over 95% of patients, with 95% mean AV syn-chronization ratio 7. The low pacing threshold and reduced rheobase and chronaxie featured by chronic implants show the high efficiency of ventricular stimulation.
5 YEARS Follow-up duration
95% OF IMPLANTS Regular VDD
95% OF PLACED CYCLES Atrium-driven stimulation
INNOVATION WITH CONSISTENCY
The VDD system by Medico includes the PHYMOS 44 MRI tetrapolar single-pass lead and the pacemaker Iris VDD MR, ensuring an advanced pacing therapy thanks to many special functions.
ATRIAL TACHYARRHYTHMIA RECOGNITION:
quick reaction to PACs, upper-rate with pseudo-Wenckebachalgorithm, mode switch to VVI or VVIR in the presence of persistent high atrial rate, with automatic tachyarrhythmiarecording through a special electrogram (iECG), which can discriminate supraventricular from ventricular tachycardias.
EJECTION CONFIRMATION AFTER VENTRICULAR PACING OR SENSING:
based on the assessment of transvalvular impedance (TVI), which increases in systole if ventricular volume decreases. It allows autoregulation of pacing energy and prevention of false-inhibition induced by electromagnetic interference or myopotentials.
iECG and TVI recorded during atrial tachycardia. The arrows indicate the P waves.TVI fluctuation demonstrates effective hemodynamics.
VENTRICULAR PACING REDUCTION:
in case of paroxysmal AVB or 2nd degree blocks with tolerated conduction ratio, the pacemaker can stop ventricular stimulation as long as the intrinsic rhythm is present and stable.
REMOTE CONTROL BY MEANS OF “ERMES” COMMUNICATING SYSTEM:
a pocket telemetric device connected to internet through a smartphone or a PC; it can be used with Iris pacemaker only.
SURVEILLANCE OF HEMODYNAMIC STABILITY:
the TVI signal averaged over a programmable number of cardiac cycles is stored and compared along the time. Relevant waveform modifications can indicate a change in ventricular mechanics.
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