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Paul Dorian

Publications and source records attributed to Paul Dorian.

8 recordsLinked to original sources
PubMed2003

Guidelines for implantable cardioverter defibrillator follow-up in Canada: a consensus statement of the Canadian Working Group on Cardiac Pacing.

A survey on the follow-up practices of patients with implantable cardioverter defibrillators (ICDs) in Canada was conducted by the Canadian Working Group on Cardiac Pacing in 1999. The survey identified the need for national guidelines. The present guidelines for ICD follow-up represent a consensus statement of the Canadian Working Group on Cardiac Pacing. They recommend that patients be assessed before hospital discharge, at two to 12 weeks following implantation, six months after implantation, and at a minimum of every six months thereafter. More frequent assessments may be required for some patients depending on associated cardiovascular problems and specific ICD devices. A typical follow-up visit should include a targeted cardiovascular assessment, interrogation of the ICD, review of telemetered data, assessment of the underlying rhythm, pacing and sensing thresholds, lead impedance and appropriate reprogramming of ICD parameters to optimize device function and longevity.

Cardiac Pacing, Artificial↗
PubMed2002

Amiodarone as compared with lidocaine for shock-resistant ventricular fibrillation.

BACKGROUND: Lidocaine has been the initial antiarrhythmic drug treatment recommended for patients with ventricular fibrillation that is resistant to conversion by defibrillator shocks. We performed a randomized trial comparing intravenous lidocaine with intravenous amiodarone as an adjunct to defibrillation in victims of out-of-hospital cardiac arrest. METHODS: Patients were enrolled if they had out-of-hospital ventricular fibrillation resistant to three shocks, intravenous epinephrine, and a further shock; or if they had recurrent ventricular fibrillation after initially successful defibrillation. They were randomly assigned in a double-blind manner to receive intravenous amiodarone plus lidocaine placebo or intravenous lidocaine plus amiodarone placebo. The primary end point was the proportion of patients who survived to be admitted to the hospital. RESULTS: In total, 347 patients (mean [+/-SD] age, 67+/-14 years) were enrolled. The mean interval between the time at which paramedics were dispatched to the scene of the cardiac arrest and the time of their arrival was 7+/-3 minutes, and the mean interval from dispatch to drug administration was 25+/-8 minutes. After treatment with amiodarone, 22.8 percent of 180 patients survived to hospital admission, as compared with 12.0 percent of 167 patients treated with lidocaine (P=0.009; odds ratio, 2.17; 95 percent confidence interval, 1.21 to 3.83). Among patients for whom the time from dispatch to the administration of the drug was equal to or less than the median time (24 minutes), 27.7 percent of those given amiodarone and 15.3 percent of those given lidocaine survived to hospital admission (P=0.05). CONCLUSIONS: As compared with lidocaine, amiodarone leads to substantially higher rates of survival to hospital admission in patients with shock-resistant out-of-hospital ventricular fibrillation.

Aged↗
PubMed2002

Quality of life improves with treatment in the Canadian Trial of Atrial Fibrillation.

BACKGROUND: The impact of atrial fibrillation (AF) and its treatment on health-related quality of life (QOL) is not well understood. We assessed QOL in patients with symptomatic AF participating in the Canadian Trial of Atrial Fibrillation. METHODS: Self-report QOL questionnaires including the Short-Form-36 (SF-36), symptom checklist (SCL) and AF Severity Scale (AFSS) were completed at baseline and 3, and 12 months after randomization. RESULTS: The study group was aged 65 +/- 10 years and 59% were male. By design, 50% of patients were randomized to amiodarone (n = 132), 25% to sotalol (n = 66), and 25% to propafenone (n = 66). Most patients had normal left ventricular function (89%). Physical (41.9 +/- 9.3 to 43.7 +/- 9.2, P =.001) and mental health (47.5 +/- 10.5 to 49.0 +/- 9.8, P =.023) summary measures from the SF-36 improved significantly from baseline to 3 months. Arrhythmia symptom frequency and severity (SCL) also improved markedly from baseline to 3 months (symptom frequency 20.4 +/- 9.4 to 16.2 +/- 9.5 and symptom severity 16.7 +/- 8.2 to 12.9 +/- 7.4, both P <.001). QOL improvements were not significantly different among the groups randomized to amiodarone, sotalol, or propafenone. However, patients with no symptomatic recurrences of AF had higher scores at 3 months on measures of global well-being than those with recurrences in the first 3 months (7.4 +/- 1.8 vs 6.9 +/- 1.8, P <.05). There were no significant QOL changes from the 3 to 12 month assessment. CONCLUSION: In patients with symptomatic AF, QOL improves after treatment, independent of the specific drug used for treatment. This is especially true for patients in whom treatment prevents AF recurrence.

Aged↗
PubMed2002

Quality of life in the Canadian Implantable Defibrillator Study (CIDS).

BACKGROUND: The primary aim of this study was to compare quality-of-life outcome between patients randomized to implantable cardioverter defibrillator (ICD) therapy and patients randomized to amiodarone treatment in the Canadian Implantable Defibrillator Study (CIDS). A secondary aim was to evaluate the effects on quality-of-life outcomes of receiving shocks from the device. METHODS: Quality of life was assessed in 317 English-speaking participants by use of the Rand Corporation's 38-item Mental Health Inventory (MHI) and the Nottingham Health Profile (NHP). Assessments were done in the hospital at baseline and with mailed questionnaires after 2, 6, and 12 months of follow-up. Sixty-two percent of patients completed the follow-up assessments at 6 and 12 months. RESULTS: Repeated measures analysis of variance revealed significant time by treatment group interaction effect on total MHI and the psychological distress and psychological well-being sub-scales, and on 5 of the 7 NHP scales (energy, physical mobility, emotional reactions, sleep disturbance, and lifestyle impairment) (P <.05). Emotional and physical health scores were shown to improve significantly in the ICD group and were either unchanged (emotional health) or deteriorated (energy and physical mobility) in the amiodarone-treated group by means of post-hoc comparisons. Quality of life did not improve in the subgroup of patients in the ICD-treated group who received > or =5 shocks from their device. CONCLUSION: Quality of life is better with ICD therapy than with amiodarone therapy. The beneficial quality-of-life effects from an ICD are not evident in patients who receive numerous shocks from their device.

Aged↗
PubMed2002

Terikalant and barium decrease the area of vulnerability to ventricular fibrillation induction by T-wave shocks.

The area of vulnerability (AOV) to ventricular fibrillation (VF) induction by high-voltage shocks has been proposed as a measure of vulnerability to VF. Biphasic shocks spanning the T wave and ranging between 50 V and the upper limit of vulnerability (ULV) to VF were delivered before and after terikalant (1 mg/kg) and barium (1.1 mg/kg load followed by 0.05-0.10 mg/kg/min maintenance) or vehicle in dogs. The AOV decreased by 34% and 28% (p < 0.01) after terikalant and barium (n = 8 dogs each), respectively. Mean ULV, defibrillation threshold (DFT), and ventricular vulnerability period (VVP) decreased by 16%, 23%, and 31% (p < 0.01), respectively, after terikalant, and by 25%, 17% (p < 0.01), and 13% (p = 0.08), respectively, after barium. Vehicle (n = 14) did not significantly alter any of these variables. The ULV was correlated with the DFT before and after terikalant (r = 0.78, p < 0.01) and barium (r = 0.83, p < 0.01). Potassium channel blockers of the current reduce the ability to induce VF; this effect may be related to the anti-fibrillatory action of class III anti-arrhythmic drugs and their ability to decrease DFT.

Action Potentials↗
PubMed2002

Combination IK1 and IKr channel blockade: no additive lowering of the defibrillation threshold.

Selective blockade of the inward rectifier potassium channel I(K1) by barium, or of the rapidly activating delayed rectifier potassium channel I(Kr) by D,L-sotalol, prolongs repolarization and reduces the defibrillation threshold (DFT). This study hypothesized that combination I(K1) and I(Kr) channel block would produce concentration-dependent additive effects on DFT and ventricular refractoriness. A range of barium and D,L-sotalol concentrations, alone and in combination, were examined with respect to DFT, ventricular effective refractory period (VERP), and ventricular fibrillation cycle length (VFCL) in 133 Langendorff-perfused rabbit hearts. Barium produced a concentration-dependent reduction of DFT (-49+/-4%), with concentration-dependent increases in VERP (26+/-6%) and VFCL (42+/-18%). D,L-Sotalol produced a concentration-dependent lowering of DFT (-53+/-6%) with a concentration-dependent increase in VFCL (34+/-8%) but not VERP. Low (1.6 microM), intermediate (3.1 microM), and high (12.5 microM) barium concentrations combined with varying D,L-sotalol concentrations produced equal or smaller decreases in DFT compared with corresponding doses of barium or D,L-sotalol alone. Except at the lowest concentrations of barium (1.6 and 3.1 microM) (p < 0.05), there was no significant additive interaction between barium and D,L-sotalol on VERP or VFCL. Combination I(K1) and I(Kr) channel block by barium and D,L-sotalol does not produce additive reduction of DFT.

Algorithms↗
PubMed2002

The effect of isoproterenol on the class III effect of azimilide in humans.

BACKGROUND: Many class III antiarrhythmic agents lose efficacy under beta-adrenergic stimulation and at high heart rates (reverse rate dependence). This effect is thought to be due to selective blockade of the rapidly (I(Kr)), but not the slowly (I(Ks)), activating component of the delayed inward rectifier potassium current. Azimilide is an investigational class III antiarrhythmic agent that blocks both IKr and IKs. METHODS: We investigated the electrophysiologic effect of azimilide with and without beta-adrenergic stimulation in humans. Right ventricular effective refractory period at cycle lengths of 600 and 400 milliseconds and monophasic right ventricular action potential duration at 90% repolarization at cycle lengths of 250, 300, 400, 500 and 600 milliseconds were measured in 13 patients at baseline. Isoproterenol was then infused to increase the heart rate to 125% of baseline, and the pacing protocol was repeated. Patients then received, in a single-blind randomized manner, azimilide dihydrochloride (4.5 mg/kg intravenous loading dose followed by 0.625 mg/kg/h) plus either isoproterenol at the previous dose, or saline. After measurements were taken, treatment groups were crossed over, the azimilide infusion was continued and the procedure repeated. RESULTS: Azimilide significantly (P < 0.05) prolonged monophasic action potential duration compared to baseline at all cycle lengths except for the 250 millisecond cycle length. In the presence of isoproterenol, azimilide maintained its class III effect, prolonging the action potential duration at 90% repolarization by a mean of 8.7 +/- 3.9 milliseconds, (3.7 +/- 1.7%), whereas isoproterenol alone shortened the action potential duration at 90% repolarization by -2.6 +/- 3.2 milliseconds (-1.2 +/- 1.4%) (P = 0.0051). Isoproterenol alone shortened the right ventricular effective refractory period by -13.6 +/- 3.4 milliseconds, whereas with isoproterenol in the presence of azimilide, the right ventricular effective refractory period was essentially unaffected (-1.4 +/- 3.4 milliseconds, P = 0.0085). CONCLUSIONS: Azimilide maintained its class III effect in the presence of isoproterenol and at increased heart rates, suggesting that IKs block may be of particular benefit in these circumstances.

Action Potentials↗