Biomedical subjects

D McAuliffe

Publications and source records attributed to D McAuliffe.

5 recordsLinked to original sources

PubMed1989

QRS morphology-dependent, concordant frequency distribution of single and repetitive forms of ventricular ectopic activity.

We tested the relationship between the frequency of single premature ventricular complexes (PVCs) of specific QRS morphologies and repetitive forms (RF) of greater than or equal to 2 PVCs. Fourteen patients with multiform PVCs and RFs underwent 8-hour, two-channel continuous electrocardiographic monitoring. After a 2-hour baseline, procainamide was administered intravenously at 25 mg/min until PVC suppression or 1000 mg. Multiple regression analysis was used to relate the frequencies of repetitive forms initiated by PVCs of the most frequent QRS morphology (M1) and the second most frequent QRS morphology (M2) to the frequency of M1 and M2 single PVCs. Parallel changes in the frequency of M1 RFs and M1 PVCs occurred in 9 of 14 patients and parallel changes in the frequency of M2 RFs and M2 PVCs occurred in 7 of 14 patients (i.e., the relationships were concordant). In two patients, M1 RFs related to M2 PVC frequency; in three patients, M2 RFs related to M1 PVC frequency (i.e., the relationships were discordant). Thus concordant frequency distributions were present in 16 of 28 (57%) comparisons, while a discordant relationship occurred in only 5 of 28 (18%) comparisons (p less than 0.005). In conclusion, there is frequent concordance in the frequency distribution of single multiform PVCs and of RFs initiated by PVCs of the same QRS morphology during a pharmacologic intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Complexes, Premature↗

PubMed1989

The clinical implication of changing unbound quinidine levels.

Pharmacodynamic and pharmacokinetic aspects pertinent to the potential clinical application of unbound quinidine levels were studied. Following heparin administration during electrophysiologic testing in 10 patients receiving quinidine, there were significant increases in the mean (+/- SD) right ventricular effective refractory period (266 +/- 24 versus 279 +/- 23; p less than 0.025), free fatty acid concentration (515 +/- 213 versus 1071 +/- 359 mmol/L; p less than 0.001), and unbound quinidine concentration (0.3 +/- 0.1 to 0.6 +/- 0.1 microgram/ml; p less than 0.001) but no changes in heart rate, corrected QT interval, or total plasma quinidine concentration. Ten control patients showed no change in the right ventricular effective refractory period following heparin administration. These findings were consistent with a heparin-induced increase in unbound drug concentration and activity that was limited to the vascular compartment. Eleven patients studied on day 3 (+/- 1) and day 10 (+/- 3) during an acute myocardial infarction showed a significant decrease in unbound quinidine fraction (12 +/- 4% versus 9 +/- 4%; p less than 0.02) accompanied by a decrease, rather than the predicted increase, in half-life (7.1 +/- 2.7 versus 6.3 +/- 2.1 hours; p less than 0.02). Volumes of distribution remained stable while the mean quinidine clearance tended to increase. Half-life correlated with albumin changes (r = -0.71; p less than 0.02). Apparently, improvement in clinical status (assumed) and drug clearance (measured) negated the direct effects of the decrease in unbound quinidine fraction. Although unbound drug concentrations should correlate best with drug dynamic and kinetic information, full knowledge of the clinical context of such measurements is needed for appropriate interpretation.

Adult↗

PubMed1989

Multiform ventricular complexes: a transitional arrhythmia form?

This study was undertaken to better characterize the role of multiform premature ventricular complexes in the classification of ventricular arrhythmias based on form and frequency. Twenty inpatients with organic heart disease and multiform ventricular complexes underwent continuous electrocardiographic monitoring with full disclosure analysis of the number and morphology of single premature ventricular complexes, of repetitive forms of greater than or equal to 2 premature ventricular complexes, and of the variability of coupling intervals (greater than or equal to 40 msec). Multiform premature ventricular complexes were of 3 +/- 1.4 (mean +/- S.D.) different QRS morphologies. Nineteen patients (95%) had repetitive forms of greater than or equal to 2 premature ventricular complexes; 18 patients (90%) showed variable coupling (125 +/- 29 msec). Repetitive forms or variable coupling were present in each (100%) of the 20 patients studied. These data suggest that multiform premature ventricular complexes may be a transitional arrhythmia, since repetitive forms almost always coexist. Variability in coupling, rather than just form and frequency, may be an electrocardiographic characteristic linking single and repetitive forms.

Adult↗

PubMed1988

QRS morphology-dependent pharmacodynamics in multiform ventricular ectopic activity.

The effect of an infusion of intravenous procainamide on the frequency of ventricular premature complexes (VCPs) of differing QRS morphologies was studied in 20 patients with multiform ectopic activity. In 17 of 20 patients, there was differential suppression of single VPCs with different QRS morphologies. VPCs of the most frequent QRS morphology and the second most frequent QRS morphology were compared with respect to the procainamide level at the escape of VPCs from 85% suppression and the duration of suppression measured from the onset of the procainamide infusion. In 8 patients, VPCs of the most frequent QRS morphology remained suppressed at lower procainamide concentrations and for longer times than did VPCs of the second most frequent QRS morphology (escape procainamide concentration = 2.8 +/- 1.7 versus 5.4 +/- 2.3 micrograms/ml, p less than 0.025; time to escape 244 +/- 138 versus 98 +/- 114 min; p less than 0.05). In 9 other patients, VPCs of the second most frequent QRS morphology remained suppressed at lower procainamide concentrations and for longer times than did VPCs of the most frequent QRS morphology (escape procainamide concentration 2.9 +/- 1.4 versus 8.3 +/- 6.3 micrograms/ml, p less than 0.025; time to escape 317 +/- 114 versus 63 +/- 80 min; p less than 0.001). Thus, in individual patients there are specific patterns of suppression of VPCs of different QRS morphologies which are independent of the frequency of each morphology. There is apparently a differential pharmacologic effect of procainamide on the foci or pathways responsible for the different QRS morphologies of multiform VPCs.

Arrhythmias, Cardiac↗

PubMed1986

Intramitochondrial dyes allow selective in vitro photolysis of carcinoma cells.

Carcinoma cell mitochondria preferentially accumulate and retain certain cationic dyes to a much greater extent than most normal cells. Thus, they can potentially serve as targets for highly selective photochemotherapy. We evaluated 10 rhodamine and cyanine dyes as carcinoma-specific mitochondrial photosensitizers in vitro. The most effective, N,N'-bis(2-ethyl-1,3-dioxolane)kryptocyanine (EDKC), caused marked, light-dependent killing of human bladder, squamous, and colon carcinoma cell lines after 30-min incubations at 1-0.01 microM but was minimally toxic to human keratinocytes and to normal monkey kidney epithelial cells (CV-1). Carcinoma cell phototoxicity was proportional to the amount of dye incorporated by the different cell lines. Selective killing ratios were 70-1000 for 0.1 microM dye and light doses of 100-175 J/cm2 between 680 and 720 nm.

Biological Transport↗