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Biomedical subjects

H L Kennedy

Publications and source records attributed to H L Kennedy.

At least 37 records · Page 2Linked to original sources
PubMed1992

Long-term prognostic significance of ambulatory electrocardiographic findings in apparently healthy subjects greater than or equal to 60 years of age.

To determine the long-term prognostic significance of frequent or complex ectopic beats and ST-segment changes on 24-hour ambulatory electrocardiogram (ECG) in apparently healthy older subjects, 98 volunteers were followed up from the Baltimore Longitudinal Study of Aging who were 60 to 85 years old and free of cardiac disease by history, physical examination and maximal treadmill testing at the time of ambulatory ECG between 1978 and 1980. Over a mean follow-up period of 10 years, coronary events developed in 14 subjects: angina pectoris in 7, nonfatal myocardial infarction in 3 and sudden cardiac death in 4. The incidence of coronary events did not differ significantly between subjects who developed the following arrhythmias and those who did not, respectively: greater than or equal to 30 supraventricular ectopic beats in any hour, 18 vs 13%; greater than or equal to 100 supraventricular ectopic beats in 24 hours, 20 vs 12%; paroxysmal atrial tachycardia, 15 vs 14%; greater than or equal to 30 ventricular ectopic complexes (VECs) in any hour, 17 vs 14%; greater than or equal to 100 VECs in 24 hours, 18 vs 14%; or repetitive VECs, 20 vs 13%. The mean 24-hour heart rate (75 +/- 8 vs 72 +/- 9 beats/min) as well as the maximal (116 +/- 20 vs 111 +/- 18 beats/min) and minimal (51 +/- 6 vs 53 +/- 7 beats/min) heart rate also did not differ between the coronary event and non-event groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Practice parameters for the management of anal fissure. The Standards Task Force American Society of Colon and Rectal Surgeons.

It should be recognized that these guidelines should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtaining the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all of the circumstances presented by the individual patient.

Fissure in Ano↗
PubMed1992

Power law analysis of the signal-averaged electrocardiogram for identification of patients with ventricular tachycardia: effect of bundle branch block.

Signal-averaged ECGs that use time-domain analysis are useful for the identification of patients at risk for ventricular tachycardia (VT). Bundle branch block (BBB) and other conduction defects reduce the value of this approach, but frequency-domain analysis has shown promise in such patients. The purpose of the present study was to examine a new frequency-domain approach to signal-averaged ECGs in patients with and without BBB: power law scaling (PLS). PLS was performed by plotting the power spectrum of the entire signal-averaged ECG on a plot of log power versus log frequency and determining the slope (beta) by least-squares regression. This method was studied in 346 patients. Results of discriminant analysis revealed better sensitivity, specificity, positive predictive value, negative predictive value, and percentage correctly predicted when this method was compared with time-domain indexes. A large proportion of the variance in PLS (19%) was found to be due to findings in patients with VT; whereas the best time-domain index, duration of the filtered QRS signal, explained only 6% of the variance in the group with VT. Mean levels of PLS (+/- standard deviation) were decreased for the group with VT (-3.55 +/- 0.95) as compared with the group without VT (-4.34 +/- 0.59; p < 0.001), suggesting a decrease in the time correlation of the signal. Thus this method of frequency-domain analysis of the signal-averaged ECG was useful in identifying patients with sustained VT despite the presence of significant conduction defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Ambulatory (Holter) electrocardiography signal-averaging: a current perspective.

Signal-averaging is an emerging new application of the ambulatory ECG. Whereas real-time signal-averaging of the high-resolution ECG has led to the measurement of abnormal QRS complex parameters and to the detection of ventricular late potentials in patients with a history of ventricular tachycardia or fibrillation at increased risk of an arrhythmic event, similar measurements can also be derived from ambulatory ECG tape recordings. This review describes the technical differences between real-time and ambulatory high-resolution ECG signal-averaging, and the early clinical studies that correlated measured QRS complex parameters and defined the agreement of late potential detection with the two technologies. Although there appears to be a promising cost-effective benefit from ambulatory ECG signal-averaging, limitations imposed by the technical differences must be recognized, and additional investigation is needed to define the appropriate clinical use and criteria for best diagnostic and prognostic value.

Electrocardiography, Ambulatory↗
PubMed1992

Efficacy of three-channel ambulatory electrocardiographic monitoring for the detection of myocardial ischemia.

The recognition of silent myocardial ischemia (SMI) has been demonstrated to have important clinical relevance. Two-channel ambulatory (Holter) electrocardiographic recording is a commonly utilized method for detecting transient electrocardiographic ST segment changes representative of SMI. It has been suggested that the analysis of two channels alone may not adequately detect SMI. We therefore evaluated the diagnostic yield of three channels using a three-channel electrocardiographic monitoring device in 46 consecutive patients (age 61 +/- 9 years) undergoing percutaneous transluminal coronary angioplasty of an isolated single-vessel stenosis. Modified bipolar chest leads V2, V5, and AVF (CM-V2, CM-V5, and CS-AVF) were utilized for analysis. The percent detection of ST segment changes from various combinations of two-lead recordings were compared to the total three leads, and an absolute transient ST segment shift (STSS) of greater than or equal to 1 mm during balloon inflation was considered as evidence of myocardial ischemia. One patient was excluded because of the need for ventricular pacing during balloon inflation. A total of 33 of 45 patients had STSS in all three leads (percent detection = 73%), while 32 (71%) had STSS in the two-lead grouping with the highest diagnostic yield (CM-V2/CM-V5; p = ns). Of the various two-lead combinations studied, leads CM-V2 and CM-V5 provided the best lead set overall for the detection of ischemic STSS. Three-channel ambulatory electrocardiographic recording only marginally improves upon the detection of ischemia when compared with standard (CM-V2/CM-V5 or CM-V5/CS-AVF) two-channel ambulatory electrocardiographic recordings.

Angioplasty, Balloon, Coronary↗
PubMed1992

Validation of computerized three-dimensional reconstruction of intravascular ultrasound: measurements of absolute luminal diameter and cross-sectional area in ex vivo human coronary arteries.

UNLABELLED: Computer based 3-dimensional reconstruction transforms 2-dimensional intravascular ultrasound images into a longitudinal format facilitating analysis of luminal narrowing. To validate the accuracy of current software in measuring coronary artery diameter and cross-sectional area, in arteries with atherosclerosis, we performed 3-dimensional reconstruction in 10 human pathologic coronary arterial segments of 10-25mm length. Images were obtained using a 4.8 French catheter with pullback speed of 1mm/sec acquired at 3 frames/sec onto VHS tape. The data were digitized and intraluminal 3-dimensional reconstruction performed using a voxel-based program. Pathologic sections were obtained every 3mm, and dimensions were measured with a resolution of 0.01 mm. Maximum, minimum, and 3 other representative diameters were recorded by an observer blinded to the ultrasound diameters. Average histo-pathologic diameters were reported, and specimen cross-sectional area was then calculated. RESULTS: In 53 sections, pathological diameters ranged from 1.4-4.5mm (mean 2.7 +/- 0.68mm) while 3-dimensional reconstructed diameters were 1.9 to 3.8mm (mean 2.6 +/- 0.54mm). Pathologic and ultrasound derived 3-dimensional reconstruction diameters had an excellent correlation (r=0.86, SEE=+/-0.36). Pathology and 3-dimensional reconstruction cross-sectional area also correlated closely (r=0.88, SEE=+/-1.50). Diameters less than 2.0mm were systematically overestimated and diameters greater than 3.5mm underestimated by 3-dimensional reconstruction. Most 3 dimensional reconstruction values were within +/- 10% of pathology, but diverged at each diameter extreme, approaching +/- 20%. Thus, computerized 3-dimensional reconstruction of ultrasound images shows excellent quantification of luminal size in the 2.0-3.5mm range, suggesting important investigative and clinical applications.

Arteries↗
PubMed1992

Ambulatory (Holter) electrocardiography technology.

Ambulatory ECG is an evolutionary cardiovascular discipline with regard to both its clinical applications and technology. With the technologic advances of the past decade, powerful personal computers have expanded the traditional clinical role of ambulatory ECG examination for cardiac arrhythmias to detection of ST-segment changes, heart-rate variability, QT interval measurement, and the signal-averaged ECG. These expanded clinical applications increase the practicality of a 24-hour ambulatory ECG on an individual cardiac disease patient and make the 24-hour ambulatory ECG one of the most cost-effective cardiovascular diagnostic tests when used properly. The current clinical developments make valid ST-segment detection and quantitation readily available and heart-rate variability an easily applied investigative tool to a wide spectrum of diseases. Automatic QT interval measurements and signal averaging of ambulatory ECG are just technologically emerging and can be expected to develop more in the near future.

Arrhythmias, Cardiac↗
PubMed1991

ACC policy statement. Recommended guidelines for training in adult clinical cardiac electrophysiology. Electrophysiology/ Electrocardiography Subcommittee, American College of Cardiology.

Training in clinical cardiac electrophysiology should take place in an Accreditation Council for Graduate Medical Education accredited cardiology program, and the electrophysiology training program itself should be accredited by the Council. Each trainee must be eligible for board certification in Internal Medicine and either eligible for certification in Cardiovascular Diseases or in a program leading to eligibility. Training faculty should be certified in clinical cardiac electrophysiology or demonstrate equivalent credentials. At least two training faculty members are preferred. The faculty must be dedicated to teaching, active in performing or promoting research and must spend a substantial portion of their time in research, teaching and practice of clinical electrophysiology. A curriculum of training should be established. Faculty experts in the related basic sciences should be available and involved in teaching. The institution should have a fully equipped clinical electrophysiology laboratory and complete noninvasive capabilities. A close working relation with a cardiac surgery faculty member skilled in surgical treatment of arrhythmias is required. Training in application of pharmacologic and all current nonpharmacologic therapies, in the outpatient and inpatient setting, is necessary. The clinical exposure must include all facets of arrhythmia diagnosis and treatment and must be quantitatively sufficient to allow the trainee to develop proficiency. The period of training should not be less than one year in addition to the period of cardiology fellowship required by the ABIM for board eligibility. A continuous period of training is preferred.

Anti-Arrhythmia Agents↗
PubMed1990

Noncardiac adverse effects and organ toxicity of moricizine during short- and long-term studies.

To determine the tolerance and safety of moricizine, the incidence and nature of its noncardiac adverse effects and organ toxicity reported during short- and long-term clinical studies were examined. From a pooled data base of 1,256 adult patients and healthy subjects, the most frequent non-cardiac adverse events were gastrointestinal (nausea) and neurologic (dizziness) complaints which occurred in 10 to 15% of patients during short-term (less than 3 months) studies and increased to 20 to 25% during long-term (greater than 12 months) studies. Adverse effects led to discontinuation of moricizine therapy in 116 patients (9%). Organ toxicity consisted predominantly of drug fever, possible thrombocytopenia and elevated liver function tests and was quite low (less than 0.7%) for both short- and long-term studies. Moricizine appears to be a well-tolerated antiarrhythmic drug with low occurrence of noncardiac adverse effects without significant serious organ toxicity.

Adult↗
PubMed1990

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)

Angiography↗
PubMed1990

Fistulotomy without external sphincter division for high anal fistulae.

Thirty-two patients with high trans-sphincteric or suprasphincteric fistulae underwent fistulotomy without external sphincter division. Fifteen patients had posterior fistulae involving the deep postanal space and 17 patients had anterior fistulae. Primary healing, after removal of the seton, occurred in 25 of the 32 patients (78 per cent). Primary healing in patients with posterior fistulae occurred in 66 per cent and in 88 per cent of patients with anterior fistulae. Following surgery, eight patients (33 per cent) reported problems controlling flatus, six patients (25 per cent) reported mucous discharge and one patient (4 per cent) complained of occasional incontinence for liquid stool. No patient experienced problems controlling solid stool nor did any patient require the use of a protective pad. These results have encouraged us to use this method as the initial procedure of choice for these more difficult fistulae. A significant number of patients can be cured of their fistula while preserving the external sphincter, thereby minimizing the impact of surgical therapy on continence.

Adult↗
PubMed1989

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)

Anti-Arrhythmia Agents↗