Leonardo Cammilli, Avio Maria Perna, Gino Grassi, Francesco Cammilli, Antonio Morra, Federico Perna.
Cardiac Surgery Lab, USL 10D, Firenze, Italy
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In the last five years a new philosophy concerning
the treatment of atrial fibrillation and dilated cardiomyopathy and congestive heart failure
(CHF) was postulated: four chamber pacing by means of multi site pacing leads was the goal.
To reach this goal, at present several leads need: in order to overcome this problem, our
investigation was performed.
Since 1993 we investigated left atrium and left ventricle pacing by means of a single catheter
placed into the coronary sinus. Since 1997 we are investigating the possibility of pacing all
four chambers with a single catheter placed into the coronary sinus, provided with a stent
to support the four electrodes.
In preliminary investigation such stent was an Elgiloy support zig-zag shaped. It was
mechanically constrained by means of a thin membrane to allow the tip placement into the
coronary sinus. Two leads, originated by dichotomical division of the primitive single lead,
carry 2 electrodes each one: the superior lead to pace right and left atrium, the inferior one
to pace right and left ventricle respectively.
The stability of the electrodes should be ensured by the stent which pushes the electrodes
towards the cardiac walls.
SURGICAL PROCEDURE. In 4 swines, under general anaesthesia, median sternotomy was
performed, the lead with its constrained support was placed into the coronary sinus via the
right atrium. When the catheter seemed placed correctly the support was expanded. Results
confirmed the possibility of pacing all the four chambers with some problems for the right heart
concerning the stability.
Anyway the main problem was represented by the impossibility of replacing the catheter and
the electrodes: should no correct position occur. Problems related with the correct placement
of electrodes and impossibility of repositioning them, suggested us to abandon this primitive
stent and to use a stent of Nitinol (programmed memory shape alloy) which allows, if the position
of the electrodes is not correct, to change, with no simple procedure anyway, the electrodes position.
In the first 2 animals in which this new system was tested, low threshold occurred; especially
about what concerns the electrodes stability, even if limited for the lasting of experiences, its
results were good.
Chronical investigations to confirm the electrical and mechanical stability of the electrodes need
as well as long term threshold and sensing testing.
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