Biomedical subjects

J W Vetter

Publications and source records attributed to J W Vetter.

6 recordsLinked to original sources

PubMed1993

Directional coronary atherectomy complications and management.

Directional coronary atherectomy provides a predictable outcome in selected cases; however, DCA may still result in significant complications in a small number of patients. Although many of the complications are similar to those associated with PTCA, some of the complications are unique or more frequently observed with DCA. These complications are often preventable with adequate case selection and appropriate technique. Because of significant differences in the atherectomy procedure compared to PTCA, the operator should recognize and understand the technical differences to prevent potentially serious complications.

Atherectomy, Coronary↗

PubMed1992

Restenosis after directional coronary atherectomy.

OBJECTIVES: This study evaluates the incidence of restenosis after successful directional coronary atherectomy and identifies risk factors for restenosis. BACKGROUND: Directional coronary atherectomy has been shown to be a safe and effective treatment of obstructive coronary artery disease; however, information regarding restenosis is limited. METHODS: Between October 1986 and December 1989, 289 patients with 332 lesions were successfully treated with directional coronary atherectomy and followed up prospectively. Clinical follow-up information was available for 98% and angiographic follow-up information was obtained for 82% at approximately 6 months, or earlier if symptoms recurred. Angiograms were quantitatively analyzed. Restenosis was defined as greater than 50% stenosis at the site of intervention. RESULTS: Seventy-four percent of patients were either asymptomatic or clinically improved after the procedure. Thirty-two percent were subsequently treated by coronary artery bypass surgery (14%), percutaneous transluminal coronary angioplasty (4%) or repeat atherectomy (13%). Angiographic evidence of restenosis was observed in 42%. The restenosis rate in native coronary arteries was 31% for primary lesions and 28% and 49%, respectively, for lesions treated with one or two previous angioplasty procedures. The restenosis rate for saphenous vein grafts was 53% for primary lesions and 58% and 82%, respectively, for lesions treated with one or two previous angioplasty procedures. The median interval to angiographically documented restenosis was 133 days. A higher restenosis rate was associated with a saphenous vein graft, hypertension, a longer lesion (greater than or equal to 10 mm), a smaller vessel diameter (less than 3 mm), a noncalcified lesion and use of a smaller (6F) device. CONCLUSIONS: Restenosis remains a limitation of directional coronary atherectomy. A subset of patients with larger vessels, shorter lesions or lesions treated with a larger (7F) device may have a more favorable outcome.

Aged↗

PubMed1991

Effect of lesion characteristics on outcome of directional coronary atherectomy.

Directional coronary atherectomy, a new transluminal procedure for treatment of obstructive lesions in coronary arteries by excision and removal of tissue, was performed on 447 lesions in 382 procedures. Successful outcome, defined as a reduction of stenosis by greater than or equal to 20% with a less than 50% residual stenosis, was achieved in 89.5% of lesions and mean stenosis was reduced from 75.9 +/- 13.3% to 14.5 +/- 22.1% (p less than 0.001). Complications included vessel occlusion during the procedure, 2.4%; vessel occlusion after the procedure, 1.3%; new lesion, 0.5%; nonobstructive guiding catheter-induced dissection, 0.3%; perforation, 0.8%; distal embolization, 2.1%; Q wave myocardial infarction, 0.8% and non-Q wave myocardial infarction, 4.2%. Twelve patients (3.1%) required coronary artery bypass surgery for these complications. The atherectomy success rate was greater than 80% and the combined atherectomy and angioplasty success rate was greater than 90% for complex morphologic features such as eccentric lesions, lengthy lesions, lesions with abnormal contour, angulated lesions, ostial lesions and lesions with branch involvement. In the presence of calcific deposition, atherectomy success rate was 52% for primary lesions and 83% for restenosed lesions. Among angiographically complex lesions, calcium was the predictor for failed atherectomy (p less than 0.0001). In summary, directional coronary atherectomy is safe and effective for treatment of obstructive lesions in coronary arteries in selected cases. In particular, it achieves a high success rate in lesions with complex morphologic characteristics, such as eccentricity, abnormal contour and ostial involvement.

Adult↗

PubMed1989

Comparison of monophasic with single and dual capacitor biphasic waveforms for nonthoracotomy canine internal defibrillation.

Monophasic and single capacitor and dual capacitor biphasic truncated exponential shocks were tested in pentobarbital-anesthetized dogs with use of a nonthoracotomy internal defibrillation pathway consisting of a right ventricular catheter electrode and a subcutaneous chest wall patch electrode. Seven dogs weighing 20.2 +/- 0.5 kg were utilized. Monophasic pulses of 10 ms duration were compared with three biphasic pulses. All biphasic waveforms had an initial positive phase (P1) followed by a terminal negative phase (P2) and the total duration of P1 plus P2 was 10 ms. The dual capacitor biphasic waveform (P1 9 ms, P2 1 ms) had equal initial voltages of P1 and P2. Two simulated single capacitor biphasic waveforms were also tested, the first designed to minimize the magnitude of P2 (P1 9 ms, P2 1 ms with initial voltage of P2 equal to 0.3 of the initial voltage of P1) and the second to maximize P2 (P1 5 ms, P2 5 ms with initial voltage of P2 = 0.5 P1). Alternating current was used to induce ventricular fibrillation and four trials of eight initial voltages from 100 to 800 V were performed for each of the four waveforms. Stepwise logistic regression was utilized to construct curves relating probability of successful defibrillation and energy. In the logistic model, the dual capacitor biphasic and single capacitor biphasic waveforms that maximized P2 were associated with significantly (p less than 0.001) lower energy requirements for defibrillation than those of the monophasic waveform. The single capacitor biphasic waveform that minimized P2 was not significantly better than the monophasic waveform.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Comparative efficacy of monophasic and biphasic truncated exponential shocks for nonthoracotomy internal defibrillation in dogs.

Pentobarbital-anesthetized dogs were studied to determine the relative efficacy of monophasic and biphasic truncated exponential shocks employing a nonthoracotomy internal defibrillation pathway that consisted of a right ventricular catheter electrode (cathode) and a subcutaneous chest wall patch electrode (anode). In part 1 of the experiments, six dogs (19.6 +/- 1.1 kg) were utilized. Monophasic pulses of 5, 7.5, 10 and 12.5 ms duration were compared with biphasic pulses of the same total duration. The biphasic pulses had an initial positive phase (P1) followed by a terminal negative phase (P2) with the initial voltage equal for each phase. For each biphasic total pulse width, five relative P1 versus P2 durations were tested (50 and 50%, 75 and 25%, 90 and 10%, 25 and 75%, 10 and 90%). Ventricular fibrillation was induced by alternating current and pulse configurations were tested randomly to determine the minimal voltage and energy for defibrillation (threshold). Biphasic shocks with P1 longer than P2 were associated with significantly lower (p less than 0.01) energy thresholds than were monophasic shocks. Additionally, there was no significant relation between pulse width and voltage or energy thresholds. In part 2 of the experiments, six dogs (20.2 +/- 1.6 kg) were studied. Monophasic shocks were compared with biphasic shocks with P1 versus P2 durations of 75 and 25% and 90 and 10% for total pulse widths of 7.5, 10 and 12.5 ms. Threshold determinations were performed as in part 1. Subsequently, five initial voltages clustered about threshold were randomly tested four times and dose-response curves constructed for each pulse configuration with the use of stepwise logistic regression. Biphasic shocks resulted in significantly lower energy (p less than 0.0001) and voltage (p less than 0.001) requirements than did monophasic shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Strength-duration curves of fixed pulse width variable tilt truncated exponential waveforms for nonthoracotomy internal defibrillation in dogs.

Six anesthetized dogs (wgt 19.6 + 1.1 kg) underwent defibrillation trials using truncated monophasic pulses of 2.5-20 msec in duration. The current pathway consisted of a 4 cm2 RV catheter electrode (cathode) and a 13.9 cm2 subcutaneous chest wall patch (anode). Fibrillation was induced by alternating current and defibrillation attempted 10 seconds later. Only one test shock was assessed for each fibrillation episode. The various durations were tested randomly, and the minimum peak voltage and energy resulting in defibrillation was determined for each. Shorter pulse durations were associated with lower energies with pulses of 2.5-15 msec having significantly lower energy thresholds than shocks of 20 msec (P less than 0.05). The relationship between duration and voltage threshold is hyperbolic with minimum voltage between 7.5 and 12.5 msec while the shortest and longest pulses were associated with the highest voltage thresholds. Shocks of 5 to 15 msec were associated with significantly lower voltage threshold than 2.5 msec pulses (P less than 0.05). The threshold average current (Iav) reached a nadir at 10 msec. Shocks in the midrange of those tested resulted in the best combination of low average current and energy requirements for defibrillation using this nonthoracotomy lead system.

Animals↗