Microwave Rotational Spectral Study of SO2-CO.

The microwave spectrum of the molecular complex of sulfur dioxide (SO2) with carbon monoxide (CO) has been studied with a pulsed-beam Fourier Transform Microwave Spectrometer (FTMW) from a pair of gas samples of 1 % by volume of SO2 and CO in Ar, and introduced via separate capillary inputs to the flow nozzle. The frequency coverage was about 7 GHz to 16 GHz for various isotopomers. The molecular structure was determined with the aid of spectral studies of isotopically substituted monomers containing 13C, 18O and 34S. The rotational analyses provide the rotational and centrifugal distortion constants for all of the isotopomers analyzed. The structure determination is compared to detailed ab initio structural calculations. The electric dipole moment components along the a- and c-axis were determined from Stark effect measurements.

Effect of selective versus nonselective beta blockade on QT dispersion in patients with nonischemic dilated cardiomyopathy.

We retrospectively examined the electrocardiograms in all of our patients with nonischemic dilated cardiomyopathy and normal sinus rhythm before and after at least 3 months of metoprolol (n = 12), bucindolol (n = 8), carvedilol (n = 6), or no beta blocker (n = 9). Both beta1-selective and nonselective beta-adrenergic blockade reduced QTc dispersion equally in patients with dilated cardiomyopathy.

Holter triage ambulatory ECG analysis. Accuracy and time efficiency.

Triage ambulatory electrocardiographic (ECG) analysis permits relatively unskilled office workers to submit 24-hour ambulatory ECG Holter tapes to an automatic instrument (model 563, Del Mar Avionics, Irvine, CA) for interpretation. The instrument system "triages" what it is capable of automatically interpreting and rejects those tapes (with high ventricular arrhythmia density) requiring thorough analysis. Nevertheless, a trained cardiovascular technician ultimately edits what is accepted for analysis. This study examined the clinical validity of one manufacturer's triage instrumentation with regard to accuracy and time efficiency for interpreting ventricular arrhythmia. A database of 50 Holter tapes stratified for frequency of ventricular ectopic beats (VEBs) was examined by triage, conventional, and full-disclosure hand-count Holter analysis. Half of the tapes were found to be automatically analyzable by the triage method. Comparison of the VEB accuracy of triage versus conventional analysis using the full-disclosure hand count as the standard showed that triage analysis overall appeared as accurate as conventional Holter analysis but had limitations in detecting ventricular tachycardia (VT) runs. Overall sensitivity, positive predictive accuracy, and false positive rate for the triage ambulatory ECG analysis were 96, 99, and 0.9%, respectively, for isolated VEBs, 92, 93, and 7%, respectively, for ventricular couplets, and 48, 93, and 7%, respectively, for VT. Error in VT detection by triage analysis occurred on a single tape. Of the remaining 11 tapes containing VT runs, accuracy was significantly increased, with a sensitivity of 86%, positive predictive accuracy of 90%, and false positive rate of 10%. Stopwatch-recorded time efficiency was carefully logged during both triage and conventional ambulatory ECG analysis and divided into five time phases: secretarial, machine, analysis, editing, and total time. Triage analysis was significantly (P < .05) more time efficient for the machine, analysis, and total time phases and required significantly more time in the editing phases. The triage analysis was limited by the inability of the automatic methodology to detect a specific VT waveform contained on one tape. This result which caused substantial loss of sensitivity for VT, emphasizes the necessity for careful quality control and editing of all automatic Holter analysis methods.

Relation of silent myocardial ischemia after coronary artery bypass grafting to angiographic completeness of revascularization and long-term prognosis.

The prevalence and characteristics of silent myocardial ischemia as detected by 24-hour ambulatory electrocardiography ST-segment depression were prospectively assessed in 94 patients examined early (1 to 3 months) and 184 patients examined late (12 months) after coronary artery bypass grafting (CABG), and followed for a mean of 48 +/- 11 (range 4 to 62) months. The relation of ambulatory electrocardiographic silent ischemia to evidence of completeness of revascularization as defined by cardiac angiography performed 1 and 12 months after CABG, and to prognosis by follow-up of adverse clinical events was analyzed. Silent ischemia was detected early in 20% (19 of 94) and late in 27% (50 of 184) of patients, and showed a mean frequency of episodes ranging from 6 to 10 episodes/24 hours with a mean duration ranging from 15 to 23 minutes. The circadian distribution of episodes disclosed a significant peak of ischemic activity during the period of 6 A.M. to noon and a secondary peak between 6 P.M. and midnight (p less than 0.01 and p less than 0.001, respectively). Silent ischemia was not found by univariate analysis to be associated with graft or anastomotic site occlusions, low graft flow rates, grafted arteries with significant distal residual stenoses or ungrafted stenotic native coronary arteries. Kaplan-Meier analysis of time to cardiac event showed that silent ischemia was not predictive of an adverse clinical event in the early years after CABG. Cox regression analysis of 30 covariates only disclosed age (relative risk 1.06 [95% confidence interval, 1.01 to 2.94]) as having an effect on time to adverse clinical event.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural history of potentially lethal ventricular arrhythmias in patients treated with long-term antiarrhythmic drug therapy.

To examine the natural history of long-term anti-arrhythmic therapy in patients with benign and potentially lethal ventricular premature complexes (VPCs), 28 patients with initial efficacy with moricizine (greater than 75% suppression of baseline mean VPCs/hr and greater than 90% suppression of repetitive VPCs) were prospectively followed for 1 to 56 (mean +/- standard deviation 25 +/- 17) months. Patients were examined during baseline placebo, anti-arrhythmic drug therapy and intermittent pulsed-placebo reexamination periods. The mean VPCs of all patients at baseline entry were 233 +/- 47 VPCs/hr, and after moricizine therapy 14 +/- 4 VPCs/hr. Follow-up demonstrated that antiarrhythmic efficacy decreased to 75% at 12 months and to 62% at 24 months. Loss of antiarrhythmic drug efficacy most commonly occurred as a "transient" event (10 patients [36%]), and efficacy was spontaneously reestablished without a change in antiarrhythmic therapy. In contrast, increased dose titration of moricizine was necessary to reestablish antiarrhythmic suppression efficacy in 4 patients (14%), and 4 patients (14%) lost antiarrhythmic drug responsiveness during follow-up. Spontaneous decrease in baseline VPCs resulted in discontinuation of antiarrhythmic therapy in 3 patients, and increase in baseline VPCs was associated with a loss of antiarrhythmic response in 2 patients. Late proarrhythmic effects (2 patients, 7%), delayed side effects necessitating drug withdrawal (6 patients, 21%) and medical events (4 patients, 14%) occurred during 56 months of follow-up. Individual serum moricizine levels remained in the therapeutic range throughout the study and did not correlate with changes in antiarrhythmic efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)

Real-time analysis ambulatory electrocardiography--clinical evaluation of cardiac arrhythmias by the Aegis system.

To evaluate the technical reliability, clinical applicability, and arrhythmia accuracy of one manufacturer's real-time analysis ambulatory ECG instrument (Aegis Medical Systems), 164 patients were simultaneously examined through a "Y" cable by both a real-time analyzer and a conventional Holter recorder. Technical failure was similar for both recorders (2% in each), and the real-time analyzer was applicable to all patients encountered. Using a randomly selected hand-counted database of 799 hours as the standard of truth, accuracy of the real-time analyzer for hourly mean heart rate, isolated ventricular ectopic beats, ventricular couplets, ventricular tachycardia, isolated supraventricular ectopic beats and supraventricular tachycardia was determined. Mean heart rate showed 96% agreement and a high correlation (r = .986) to hand-counted values. Real-time analysis overall sensitivity, positive predictive accuracy, and false positive rate for the Aegis Medical System were (a) for isolated ventricular ectopic beats--92%, 92%, and 8%, (b) for ventricular couplets--80%, 97%, and 3%, (c) ventricular tachycardia--81%, 92%, and 8%, (d) supraventricular ectopic beats--81%, 82%, and 18%, and (e) for supraventricular tachycardia--75%, 89%, and 11%. Arrhythmia analysis was valid for mean heart rate and ventricular arrhythmias, but showed lower sensitivities in detection of low prevalence (1-60 b/Hr) ventricular couplets (72%) and ventricular tachycardia (43%). Significant inaccuracies for some densities of supraventricular arrhythmia were also found. This study found the real-time analysis ambulatory ECG similar to conventional Holter recording for technical reliability and patient applicability. Given the limitations of currently available real-time analysis ambulatory ECG systems, it is a promising technology.

Serum digoxin concentrations during ethmozine antiarrhythmic therapy.

The potential for pharmacokinetic drug interaction between ethmozine (moricizine HCl), a phenothiazine class I antiarrhythmic investigational drug, and digoxin was evaluated in 13 cardiac patients with normal renal function. Antiarrhythmic therapy was initiated in patients with potentially lethal (nonlife-threatening) ventricular arrhythmias (greater than 30 ventricular ectopic beats [VEB]/hr) who were receiving maintenance digoxin therapy for congestive heart failure and/or atrial fibrillation. Serum digoxin concentrations of patients were measured frequently by radioimmunoassay and plasma ethmozine concentrations by high-performance liquid chromatographic methods. Patients entered a short-term (4 weeks) single-blind, placebo controlled ethmozine protocol with an option to receive long-term (1 to 6 months) open-label maintenance ethmozine therapy. Ambulatory ECGs (48 hour) used to assess antiarrhythmic efficacy of ethmozine during each week of the short-term protocol showed that 77% of patients demonstrated greater than 90% mean hourly frequency suppression of all forms of ventricular ectopy. Serum digoxin concentrations during short-term ethmozine dosing showed a nonsignificant (p greater than 0.05) increase of 10% to 15% (mean 0.91 ng/ml to 1.13 ng/ml). The short-term protocol serum digoxin levels correlated closely with serum digoxin concentrations during placebo therapy (1st week, r = 0.90; 2nd week, r = 0.87). Serum digoxin concentrations were not significantly different (p greater than 0.05) from placebo values at the end of 1, 3, and 6 months of maintenance ethmozine therapy. Thus, we conclude that ethmozine administered in an antiarrhythmic efficacious dosage (10 mg/kg/day) showed no important clinical or statistically significant change in serum digoxin concentrations of cardiac patients with normal renal function.

Cardiac arrhythmias in a population admitted to an acute alcoholic detoxification center.

To characterize the relationship between acute alcohol ingestion and its withdrawal with cardiac arrhythmias, we studied 38 patients admitted to an acute community alcoholic detoxification center with 24-hour ambulatory ECGs and serum ethanol levels. We found a mild correlation between the serum ethanol level and the mean rate of ventricular ectopic beats/hour (rs = 0.34, p less than 0.05). Nonsustained ventricular tachycardia and atrial fibrillation were more common in patients found to have evidence of previous underlying organic heart disease. There was no change in the prevalence of cardiac arrhythmias in this population after 2 weeks of ethanol abstinence as judged by repeat 24-hour ambulatory ECG. We conclude that in patients admitted to an acute detoxification center, cardiac arrhythmias are found more commonly in those with underlying organic heart disease, and these arrhythmias do not appear to change after 2 weeks of abstinence from alcohol ingestion.

Long-term follow-up of asymptomatic healthy subjects with frequent and complex ventricular ectopy.

From 1973 to 1983 we followed 73 asymptomatic healthy subjects who were discovered to have frequent and complex ventricular ectopy. Ventricular ectopy in these subjects was measured by 24-hour ambulatory electrocardiography, which showed a mean frequency of 566 ventricular ectopic beats per hour (range, 78 to 1994), with multiform ventricular ectopic beats in 63 per cent, ventricular couplets in 60 per cent, and ventricular tachycardia in 26 per cent. Asymptomatic healthy status was confirmed by extensive noninvasive cardiologic examination, although cardiac catheterization of a subsample of subjects disclosed serious coronary artery disease in 19 per cent. Follow-up for 3.0 to 9.5 years (mean, 6.5) was accomplished in 70 subjects (96 per cent) and documented one sudden death and one death from cancer. Calculation of a standardized mortality ratio (Monson's U.S. data, 8th revision) for 448 person-years of follow-up indicated that 7.4 deaths were expected, whereas 2 occurred (standardized mortality ratio, 27; P less than 0.05). A comparison of survival of the study cohort with that of persons without coronary artery disease or with mild disease, patients with moderate disease, and men with unrecognized myocardial infarction showed a favorable prognosis for the study cohort over 10 years. We conclude that the long-term prognosis in asymptomatic healthy subjects with frequent and complex ventricular ectopy is similar to that of the healthy U.S. population and suggests no increased risk of death.

Ambulatory blood pressure in healthy normotensive males.

Noninvasive ambulatory blood pressure examinations were obtained during 24 hours in 72 healthy normotensive males. Blood pressure and heart rate measurements were analyzed for the mean 24-hour work, home, and sleep periods, for the percent of elevated blood pressure readings, and for the hourly maximum and minimum blood pressure by age per decade. Mean 24-hour ambulatory blood pressure showed no significant differences (p greater than 0.05) for systolic blood pressures among the age groups, but lower diastolic blood pressures were found in males younger than age 40 (p less than 0.05). Few differences existed between mean ambulatory systolic and diastolic blood pressures obtained during the work or home periods, but a significant (p less than 0.01) lowering of mean systolic and diastolic blood pressure occurred during sleep for each age group. There was a trend of an increasing percent of elevated blood pressure measurements with increasing age, although mean blood pressures within each activity period showed few differences. Ninety-two percent of subjects showed their hour of maximum blood pressure during wake activity with broad variability in either the work or home period, whereas 86% of subjects uniformly demonstrated their minimum blood pressure in the early morning hours.