Leonardo Cammilli, Gino Grassi*,
Antonio Morra**, Avio Maria Perna***, Francesco Cammilli°, Pietro Liguori°, Francesco
Furlanello°.
Cardiac Surgery "Ulivella" USL 10D, Florence, *Biomedical Equipment
Technol. SNC, Sesto Fiorentino, **R&D Dept. MEDICO S.p.A., Padova, ***Cardiac Surgery
Experimental Laboratory, USL 10D, Florence, °Cardiological and Arrhythmological Dept.,
Santa Chiara Hospital, Trento, Italy
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Since in February 1980 a ICD was implanted for the
first time in a human1, many improvements were made.
But, at present, many and great problems affect again the implantable cardioverter
defibrillators (ICDs). They are the following: loss of consiousness of the patients before
and during the delivery of the electrical shock, with related consequences; impaired and
poor quality of life related to the loss of consciousness; dramatic and intolerable pain
when the electrical shock is delivered in conscious patients; risk of spurious shock due
to incorrect VF diagnosis; high energy delivery; influence of body position on the
threshold of defibrillation which is lower in supine position and it increases when the
patient is in upright position so reducing the safety margin of defibrillation.
When ventricular fibrillation occurs, about a dozen of seconds pass before the
delivery of electrical shock. The loss of the consciousness is the consequence. This time
is necessary to charge the capacitor used for the shock, besides, this period of time
allows the loss of consciousness which avoids to the patient the intolerable pain due to
the high energy shock (to 34 J for ventricular defibrillation and to 10 J for atrial
cardioversion).
If the time of capacitor charge can be reduced and even the shock energy could be
reduced, this shall not be sufficient to eliminate or to reduce the pain provoked by the
shock itself.
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