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Biomedical subjects

R W Harper

Publications and source records attributed to R W Harper.

At least 73 records · Page 4Linked to original sources
PubMed1987

The role of coronary artery disease in complications of abdominal aortic aneurysm surgery.

Coronary artery disease (CAD) is a major cause of morbidity and mortality after elective surgical repair of abdominal aortic aneurysm (AAA). The aim of this study was to determine the relationship between the extent of CAD observed in coronary angiograms (more than 50% stenosis) and the frequency of postoperative myocardial ischemic complications in a consecutive series of 84 patients who underwent elective AAA repair. Ninety-four percent of the patients with clinical evidence of CAD had significant disease as observed in coronary angiograms and eight patients had left main CAD. Seventy-two patients underwent AAA repair with a mortality rate of 1.4%; five patients had preliminary myocardial revascularization, and AAA surgery was not recommended for four patients because of severe cardiac disease. Postoperative myocardial ischemic complications occurred in 13.4% of the patients who had undergone surgery--almost exclusively in patients with clinical evidence of CAD. Both myocardial ischemia and preoperative intervention were more frequent in patients with double- or triple-vessel disease than in patients with less extensive disease. Patients with symptoms and with double- or triple-vessel CAD have a high risk of developing myocardial ischemia after AAA surgery. Preliminary myocardial revascularization may be beneficial in this group of patients.

Aged↗
PubMed1986

Atypical Wenckebach block and concealed conduction.

Following exercise testing, a 71-year-old man developed atrial tachycardia with a unusual form of conduction disturbance: 4:2 atrioventricular (A-V) block. This pattern of A-V block is explainable by two different mechanisms of concealed conduction: two different levels of block in the A-V nodal region and dual A-V nodal pathways with concealed retrograde conduction of P waves. These concepts can also explain a variety of other unusual conduction disturbances.

Aged↗
PubMed1985

Assessment of hemodynamic significance of isolated stenoses of the left anterior descending coronary artery using thallium-201 myocardial scintigraphy.

This study tests the hypothesis that the results of stress thallium-201 myocardial perfusion scans (TI-201) are related to the mean transstenotic pressure gradient of coronary stenoses independent of the percent luminal diameter narrowing seen at angiography. The 22 study patients (20 men, 2 women, mean age 47 years, range 30 to 62) had no previous myocardial infarction. Each underwent a symptom-limited, erect bicycle TI-201 test off antianginal therapy, shortly before percutaneous transluminal coronary angioplasty for isolated left anterior descending coronary artery stenosis. The percent narrowing, mean gradient at percutaneous transluminal coronary angioplasty and presence of a visually apparent TI-201 defect were independently evaluated and results compared. All 4 patients with 90% or greater diameter narrowing had positive TI-201 responses, and the mean gradient was 72 +/- 11 mm Hg. Among the 18 patients with less than 90% diameter narrowing, the mean gradient was higher (p less than 0.001) in the 11 with a positive TI-201 (63 +/- 15 mm Hg) than in the 7 with a negative TI-201 (33 +/- 20 mm Hg), but their percent narrowing did not differ significantly (72 +/- 14% vs 66 +/- 19%). Multiple regression analysis showed that the presence of a TI-201 defect was a strong (p = 0.003) and percent narrowing (p = 0.048) a weak independent predictor for gradient. When the mean gradient was normalized for the prestenotic pressure, both percent narrowing (p = 0.003) and TI-201 defects (p = 0.006) were significant independent predictors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Value of combined assessment of global and segmental ventricular contraction with right anterior oblique ECG-gated first-pass and left anterior oblique equilibrium radionuclide ventriculography.

A semi-automated, variable-region-of-interest method of analysis was used to measure both global and segmental left ventricular (LV) and global right ventricular (RV) contraction with ECG-gated first-pass and equilibrium radionuclide ventriculography. Normal values were defined in 20 healthy volunteers, and in 24 symptomatic patients, the results were compared with right anterior oblique (RAO) contrast left ventriculography. The global LV ejection fraction (LVEF) obtained by equilibrium imaging in the left anterior oblique (LAO) projection correlated closely with the results obtained by the gated first-pass method in the RAO projection (r = 0.95) and those obtained with contrast left ventriculography (r = 0.94); furthermore, the interobserver variability was small (r = 0.985). The normal values for LVEF obtained using radionuclide techniques and contrast ventriculography did not differ, but with the equilibrium radionuclide method, the RV ejection fraction (RVEF) values were underestimated in comparison to those obtained by the RAO gated first-pass technique. In five patients with localised inferior segmental akinesis at contrast angiography, the RAO first-pass cine display demonstrated a corresponding wall-motion abnormality in all cases, but LAO equilibrium cine displays did so in only one out of five patients. For segmental quantitation of LV contraction, a computer programme defined the ventricular edge, divided the RAO LV images into five segments and determined both the segmental area contraction (SAC) and the counts-based segmental ejection fraction (SEF). Radionuclide SAC measurements correlated very strongly with SEF measurements (r = 0.94-0.99). Both radionuclide SAC and radionuclide SEF correlated well with contrast angiographic SAC, except in the inferobasal segment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Control of refractory supraventricular arrhythmias after unsuccessful closed-chest His bundle ablation.

Six patients underwent attempted catheter ablation of the His bundle for control of refractory supraventricular tachyarrhythmias. Permanent complete heart block was achieved in only three patients. All six patients have remained asymptomatic without antiarrhythmic medications over a follow-up period of six to 17 months (mean 10 months). There were no complications of the procedure apart from mild elevation of creatine kinase levels in three patients. In this series, resumption of atrioventricular (AV) conduction following attempted His bundle ablation was not associated with recurrence of symptomatic arrhythmias. Preservation of AV conduction may also obviate the need for permanent ventricular pacing.

Adult↗
PubMed1985

Lipoprotein predictors of the severity of coronary artery disease in men and women.

In this study we examined the relationships between levels of several components of plasma lipoproteins and severity of coronary artery disease in 65 men and 42 women who underwent coronary arteriography for suspected coronary disease. Severity of coronary atherosclerosis was scored as the extent of disease seen at arteriography. Univariate analyses of the relationships between the plasma lipoprotein parameters and score for severity of atherosclerosis revealed a marked difference between men and women. In men, the score for severity of atherosclerosis was strongly related to the low-density lipoprotein (LDL) cholesterol and apolipoprotein B concentrations, whereas in women it was related to the triglyceride concentrations in plasma intermediate-density lipoprotein (IDL) and LDL and to the cholesterol and apolipoprotein B concentrations in IDL. The significance of these correlations was not negated by possible confounding factors such as alcohol intake, diabetes, and treatment with thiazides and beta-adrenergic blockers. Stepwise regression analyses of data adjusted for weight and age indicated that 22% of the variation in the score for severity of atherosclerosis could be accounted for by levels of LDL cholesterol in men. No other lipoprotein parameter could account for any further variation. In contrast, cholesterol did not account for any variation in the score for severity of atherosclerosis in women, whereas plasma triglyceride accounted for 16% of the observed variation in this group. No relationships were found between score for severity of atherosclerosis and high-density lipoprotein cholesterol or plasma apolipoprotein A-I concentrations in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Improving the nursing climate for cost containment.

What steps can you take to create an organizational climate conducive to implementing cost containment activities? One hospital's solution was to broaden the role of its nurse managers, strengthen unit level problem solving, and more creatively use existing resources. The authors relate the specific elements and benefits of each approach.

Administrative Personnel↗
PubMed1984

Usefulness of intravenous propranolol in predicting left anterior descending blood flow during anterior myocardial infarction.

The effect of propranolol on precordial ST-segment elevation was studied in 24 patients with acute anterior myocardial infarction. The electrocardiographic response to the drug was correlated with the early angiographic appearance of the left anterior descending coronary artery (LAD). After a 30-minute observation period, intravenous propranolol (average dose 3.5 +/- 2.2 mg) was given a mean of 2.8 +/- 1.9 hours after the onset of persistent chest pain. Coronary angiography was performed 3.6 +/- 2.0 hours after the onset of symptoms. Patients were classified into 2 groups according to the angiographic findings. Group A consisted of 7 patients with a stenotic but patent LAD and 1 patient with excellent collateral blood flow to that area. Group B consisted of 16 patients with a completely occluded LAD and poor or absent collateral blood flow. Patients in group A showed a mean reduction in precordial ST-segment elevation of 77 +/- 18% and patients in group B showed a mean reduction of 13 +/- 14% (p less than 0.005). Left ventricular ejection fraction at discharge was 0.6 +/- 0.07 in group A and 0.37 +/- 0.08 in group B (p less than 0.001). Thus, the electrocardiographic response to intravenous propranolol given early in the course of acute anterior myocardial infarction predicts the presence of blood flow to the infarcting zone. The combination of residual blood flow and reduction of ST-segment elevation secondary to propranolol is associated with preservation of ventricular function.

Blood Pressure↗
PubMed1984

Oral beta-adrenergic blockade with metoprolol in chronic severe dilated cardiomyopathy.

A double-blind crossover trial was performed to assess the effect of metoprolol in 10 patients (mean age 55 years) with severe dilated cardiomyopathy. All patients clinically had idiopathic dilated cardiomyopathy; however, at coronary angiography, four had occult coronary disease. All were in New York Heart Association functional class III with a left ventricular ejection fraction less than 35% as assessed by rest radionuclide ventriculography. Studies were performed before treatment, after 4 weeks of metoprolol therapy and after 4 weeks of placebo administration. Erect bicycle sprint exercise was used to determine maximal work load. Hemodynamic variables and radionuclide left ventricular ejection fraction were recorded at rest and during graded supine bicycle exercise. Cardiac medications were unchanged throughout the trial. The mean (+/- standard error of the mean) dose of metoprolol was 130 +/- 13 mg/day. Metoprolol did not change symptoms, chest X-ray findings or exercise tolerance (baseline 700 +/- 73, placebo 690 +/- 85, metoprolol 710 +/- 81 kilopond-meters [kpm]/min). Metoprolol produced a significant decrease in heart rate at rest and during exercise (p less than 0.001). Mean blood pressure and left ventricular filling pressure did not differ significantly in the baseline, placebo and metoprolol studies. There was a slight, but significant (p less than 0.05) decrease in cardiac index with metoprolol compared with placebo and baseline studies. The small, but significant increase in left ventricular ejection fraction from baseline to the metoprolol and placebo studies (p less than 0.001) was considered a result of spontaneous improvement rather than of therapy. No significant differences were found between the patients with and without coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1984

A digital timing and display unit for intraoperative mapping of cardiac arrhythmias.

An inexpensive display and timing unit incorporating a multichannel signal delay has been developed for mapping the heart during electrophysiological surgery. It provides a continuous digital readout of the time relationships between 3 intracardiac electrograms and the surface electrocardiogram. The electrograms are displayed on a storage oscilloscope with an automatic erase facility. This unit is used to locate accessory atrioventricular connections in the Wolff-Parkinson-White syndrome, to map ventricular tachycardias and to locate the bundle of His. The design has been refined during 5 years of use in over 200 operative procedures.

Arrhythmias, Cardiac↗
PubMed1983

Incremental value of clinical assessment, supine exercise electrocardiography, and biplane exercise radionuclide ventriculography in the prediction of coronary artery disease in men with chest pain.

The incremental value of clinical assessment, exercise electrocardiography (ECG) and biplane radionuclide ventriculography (RVG) in the prediction of coronary artery disease (CAD) was assessed in 105 men without myocardial infarction who were undergoing coronary angiography for investigation of chest pain. Independent clinical assessment of chest pain was made prospectively by 2 physicians. Graded supine bicycle exercise testing was symptom-limited. Right anterior oblique ECG-gated first-pass RVG and left anterior oblique ECG-gated equilibrium RVG were performed at rest and exercise. Regional wall motion abnormalities were defined by agreement of 2 of 3 blinded observers. A combined strongly positive exercise ECG response was defined as greater than or equal to 2 mm ST depression or 1.0 to 1.9 mm ST depression with exercise-induced chest pain. A multivariate logistic regression model for the preexercise prediction of CAD was derived from the clinical data and selected 2 variables: chest pain class and cholesterol level. A second model assessed the incremental value of the exercise test in prediction of CAD and found 2 exercise variables that improved prediction: RVG wall motion abnormalities, and a combined strongly positive ECG response. Applying the derived predictive models, 37 of the 58 patients (64%) with preexercise probabilities of 10 to 90% crossed either below the 10% probability threshold or above the 90% threshold and 28 (48%) also moved across the 5 and 95% thresholds. Supine exercise testing with ECG and biplane RVG together, but neither test alone, effectively adds to clinical prediction of CAD. It is most useful in men with atypical chest pain and when the ECG and RVG results are concordant.

Adult↗
PubMed1983

Recent experience with transeptal catheterization.

We report our recent experience of 207 consecutive transeptal catheterizations performed in the following groups of patients: aortic valve disease in 152, mitral valve disease in 20, combined aortic and mitral valve disease in 11, hypertrophic obstructive cardiomyopathy in 11, assessment of prosthetic cardiac valves in nine, and four miscellaneous. Transeptal catheterization failed in 20 patients. There was no attempt to advance the transeptal catheter from the left atrium into the left ventricle in 18 patients, and failure to advance the transeptal catheter from the left atrium into the left ventricle occurred in 13 patients. Transeptal catheterization was achieved in a mean time of 9.7 +/- 4.6 SD min. There were no deaths, two major and four minor complications. We conclude that transeptal catheterization remains a useful technique that in experienced hands is both rapid and safe.

Adult↗
PubMed1983

Amiodarone therapy for life threatening or refractory cardiac arrhythmias.

Amiodarone was used in 40 patients with life-threatening or refractory tachyarrhythmias. Eighteen patients had recurrent ventricular tachycardia of whom 13 had suffered a cardiac arrest. Control has been excellent or good in 17 of these 18 patients during an average follow-up period of 10 months. A further 22 patients had supraventricular arrhythmias, including three with Wolff-Parkinson-White syndrome and paroxysmal atrial fibrillation. In 20 of these control has been excellent or good. The mean daily maintenance dose of amiodarone was 300 mg for patients with ventricular tachyarrhythmias and 200 mg for those with supraventricular tachyarrhythmias. Side-effects were common and included corneal microdeposits, skin rash and discolouration, alteration in thyroid function, and symptomatic bradycardia. Serious adverse effects were uncommon however and necessitated discontinuation of the drug in only two patients. Amiodarone did not appear to precipitate or exacerbate cardiac failure in any patient although many had severe left ventricular dysfunction. We conclude that amiodarone is effective in the therapy of life-threatening or refractory cardiac arrhythmias.

Adolescent↗