ABSTRACT
OBJECTIVES: The ASD2 (Acute Extravascular Defibrillation, Pacing, and Electrogram) study evaluated the ability to adequately sense, pace, and defibrillate patients with a novel implantable cardioverter-defibrillator (ICD) lead implanted in the substernal space. BACKGROUND: Subcutaneous ICDs are an alternative to a transvenous defibrillator system when transvenous implantation is not possible or desired. An alternative extravascular system placing a lead under the sternum has the potential to reduce defibrillation energy and the ability to deliver pacing therapies. METHODS: An investigational lead was inserted into the substernal space via a minimally invasive subxiphoid access, and a cutaneous defibrillation patch or subcutaneous active can emulator was placed on the left mid-axillary line. Pacing thresholds and extracardiac stimulation were evaluated. Up to 2 episodes of ventricular fibrillation were induced to test defibrillation efficacy. RESULTS: The substernal lead was implanted in 79 patients, with a median implantation time of 12.0 ± 9.0 min. Ventricular pacing was successful in at least 1 vector in 76 of 78 patients (97.4%), and 72 of 78 (92.3%) patients had capture in ≥1 vector with no extracardiac stimulation. A 30-J shock successfully terminated 104 of 128 episodes (81.3%) of ventricular fibrillation in 69 patients. There were 7 adverse events in 6 patients causally (n = 5) or possibly (n = 2) related to the ASD2 procedure. CONCLUSIONS: The ASD2 study demonstrated the ability to pace, sense, and defibrillate using a lead designed specifically for the substernal space.
Subject(s)
Arrhythmias, Cardiac/therapy , Cardiac Pacing, Artificial , Defibrillators, Implantable , Aged , Cardiac Pacing, Artificial/adverse effects , Cardiac Pacing, Artificial/statistics & numerical data , Defibrillators, Implantable/adverse effects , Defibrillators, Implantable/statistics & numerical data , Electrocardiography , Female , Humans , Male , Mediastinum/surgery , Middle Aged , Prospective Studies , Prosthesis Implantation/adverse effects , Prosthesis Implantation/methods , Prosthesis Implantation/mortality , Prosthesis Implantation/statistics & numerical data , Sternum/surgeryABSTRACT
We identified 46 patients with angiographically normal coronary arteries and 16 patients with minor irregularities (luminal narrowing < or =30%) who had repeat coronary angiograms obtained at our institution during the subsequent 15-year period. On follow-up angiograms, 19 of 46 (41%) in the normal coronary group and 13 of 16 (81%) in the minor lesion group showed progression of coronary artery disease (CAD). Five patients (11%) with no angiographic luminal CAD at the time of their baseline angiogram developed an acute myocardial infarction during the follow-up period. Patients in group 1 progressed from no vessels with angiographic lesions to a mean of 0.70 +/- 0.90 vessels diseased and a mean angiographic narrowing of 24 +/- 34% at the time of their follow-up angiograms, yielding a CAD progression rate of 2.6% luminal narrowing per year. Patients in group 2 had a mean progression of 0.69 +/- 0.79% of their vessels and a mean progression in their narrowing of 34 +/- 21%, yielding a CAD progression rate of 6.0% luminal narrowing per year. In conclusion, CAD can manifest late, or more likely, many patients with apparently normal coronary arteries have intimal CAD undetectable by angiography.
