A correlation found between contact allergy to stent material and restenosis of the coronary arteries.

BACKGROUND: Metallic implants, stents, are increasingly being used especially in patients with stenosis of the cardiac vessels. Ten to thirty per cent of the patients suffer from restenosis regardless of aetiology. We have shown increased frequency of contact allergy to stent metals in stented patients. OBJECTIVES: To we evaluate whether contact allergy to stent material is a risk factor for restenosis. METHODS: Patients with stainless steel stents, with or without gold plating, were epicutaneously tested and answered a questionnaire. The restenosis rate was evaluated. RESULTS: We found a correlation between contact allergy to gold, gold stent, and restenosis (OR 2.3, CI 1.0-5.1, P = 0.04). The risk for restenosis was threefold increased when the patient was gold allergic and stented with a gold-plated stent. An increased degree of chest pain in gold-allergic patients stented with gold-plated stent was found. CONCLUSIONS: We found a correlation between contact allergy to gold, gold-stent, and restenosis. It may be of importance to consider contact allergy when developing new materials for stenting.

Non-invasive evaluation of ventricular refractoriness and its dispersion during ventricular fibrillation in patients with implantable cardioverter defibrillator.

BACKGROUND: Local ventricular refractoriness and its dispersion during ventricular fibrillation (VF) have not been well evaluated, due to methodological difficulties. METHODS: In this study, a non-invasive method was used in evaluation of local ventricular refractoriness and its dispersion during induced VF in 11 patients with VF and/or polymorphic ventricular tachycardia (VT) who have implanted an implantable cardioverter defibrillator (ICD). Bipolar electrograms were simultaneously recorded from the lower oesophagus behind the posterior left ventricle (LV) via an oesophageal electrode and from the right ventricular (RV) apex via telemetry from the implanted ICD. VF intervals were used as an estimate of the ventricular effective refractory period (VERP). In 6 patients, VERP was also measured during sinus rhythm at the RV apex and outflow tract (RVOT) using conventional extra stimulus technique. RESULTS: Electrograms recorded from the RV apex and the lower esophagus behind the posterior LV manifested distinct differences of the local ventricular activities. The estimated VERPs during induced VF in the RV apex were significantly shorter than that measured during sinus rhythm using extra stimulus technique. The maximal dispersion of the estimated VERPs during induced VF between the RV apex and posterior LV was that of 10 percentile VF interval (40 +/- 27 ms), that is markedly greater than the previously reported dispersion of ventricular repolarization without malignant ventricular arrhythmias (30-36 ms). CONCLUSIONS: This study verified the feasibility of recording local ventricular activities via oesophageal electrode and via telemetry from an implanted ICD and the usefulness of VF intervals obtained using this non-invasive technique in evaluation of the dispersion of refractoriness in patients with ICD implantation.

Improvement of Echocardiographic M-Mode Detection of Ventricular Precontraction in the Wolff-Parkinson-White Syndrome by Transesophageal Atrial Pacing.

BACKGROUND: The purpose of this study was to evaluate the accuracy of conventional M-mode echocardiography in localizing the site of the accessory pathway in 21 patients with overt Wolff-Parkinson-White (W-P-W) syndrome during sinus rhythm (SR) and during transesophageal atrial stimulation (TAS). METHODS: The invasive electrophysiological study was used as a reference, and the results were compared with the pathway localization obtained through algorithmic interpretation of the 12-lead electrocardiogram during SR. Echocardiographic left parasternal short-axis recordings were performed during SR and TAS (100-120 beats/min). The shortest electromechanical interval measured at six different sites of the atrioventricular valve plane from the onset of the delta wave to the peak of the precontraction defined the pathway localization. RESULTS: Correct localization of the accessory pathway with echocardiography could be attained in 14 patients during SR (14 of 21, or 66%). With the aid of TAS, correct pathway localization was achieved for an additional 2 patients, making a total of 16 patients (76%). During TAS, precontraction was enhanced in 63% of the patients. With the algorithmic electrocardiographic interpretation, the localization of the accessory pathway was correct in 13 of the 21 patients (62%). The differences were not significant. CONCLUSION: M-mode echocardiography is a simple and readily available method for the identification of precontraction. The method is comparable to pathway localization through algorithmic ECG interpretation during SR. Transesophageal left atrial pacing during echocardiography can amplify the precontraction and thereby facilitate the interpretation of the wall motions.