Catheter ablation in the control of cardiac arrhythmias.
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Biomedical subjects
Publications and source records attributed to D E Ward.
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Two containers ("Iowa" and "Virginia") commonly used for transporting donor corneas, and various packing methods were evaluated for constancy of temperature maintenance. The larger Iowa container was found to be superior for extended storage. Packing methods that allowed the vials (containing McCarey-Kaufman medium) to be in direct contact with wet ice or with ice water resulted in the best cooling. Direct contact with supercooled ice may cause freezing of the medium. Separating the vials from the ice water slush by dry foam rubber or Styrofoam did not allow adequate cooling. Heat sealing the vials in a plastic bag containing minimal air permitted proper cooling and may reduce the risk of contamination from the ice water.
Implantation of internal cardioverter defibrillators (ICDs) for treatment of malignant ventricular arrhythmias is complicated by failure of therapy or inappropriate shocks. We studied 81 patients (age range 16-72 years; mean 48 +/- 13 years) who underwent ICD implantation for device therapy. The underlying aetiology was ischaemic heart disease (39%), cardiomyopathies (32%) and others (28%). Information regarding shocks was collected using Holter monitoring, telemetry or device memory (stored electrograms) and lastly by clinical follow-up. Fifty-eight patients completed 36 months of follow-up. Thirty-five patients experienced 337 spontaneous shocks, appropriate in 21, inappropriate in 12, and both in two patients. Of the 74 episodes of inappropriate discharges for rhythms other that ventricular tachycardia (VT) or ventricular fibrillation(VF), 55 percent were due to supraventricular arrhythmias (atrial flutter or fibrillation). Lead malfunction occurred in four and the device was replaced in two. Additional drugs controlled AF in one. There was no mortality in any of the 81 patients. The frequency of shocks was highest in the first six months after implantation and atrial fibrillation remains the main cause. In conclusion, inappropriate shocks are frequent in patients undergoing ICD implantation.