An entirely subcutaneous implantable cardioverter-defibrillator.
BACKGROUND
Implantable cardioverter-defibrillators (ICDs) prevent sudden death from cardiac causes in selected patients but require the use of transvenous lead systems. To eliminate the need for venous access, we designed and tested an entirely subcutaneous ICD system.


METHODS
First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients.


RESULTS
The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (+/-SD) energy requirement (36.6+/-19.8 J vs. 11.1+/-8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10+/-1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia.


CONCLUSIONS
In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. (ClinicalTrials.gov numbers, NCT00399217 and NCT00853645.)
Bardy
Gust H
GH
Seattle Institute for Cardiac Research, Seattle, WA, USA. gbardy@sicr.org
Smith
Warren M
WM
Hood
Margaret A
MA
Crozier
Ian G
IG
Melton
Iain C
IC
Jordaens
Luc
L
Theuns
Dominic
D
Park
Robert E
RE
Wright
David J
DJ
Connelly
Derek T
DT
Fynn
Simon P
SP
Murgatroyd
Francis D
FD
Sperzel
Johannes
J
Neuzner
Jörg
J
Spitzer
Stefan G
SG
Ardashev
Andrey V
AV
Oduro
Amo
A
Boersma
Lucas
L
Maass
Alexander H
AH
Van Gelder
Isabelle C
IC
Wilde
Arthur A
AA
van Dessel
Pascal F
PF
Knops
Reinoud E
RE
Barr
Craig S
CS
Lupo
Pierpaolo
P
Cappato
Riccardo
R
Grace
Andrew A
AA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D004567:Electrodes, Implanted; D004867:Equipment Design; D005260:Female; D006331:Heart Diseases / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013318:Stroke Volume; D055815:Young Adult