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Biomedical subjects

R B Leman

Publications and source records attributed to R B Leman.

34 records · Page 2Linked to original sources
PubMed1987

Predictors of outcome for aortic valve replacement in patients with aortic regurgitation and left ventricular dysfunction: a change in the measuring stick.

Although left ventricular function is generally regarded as a key determinant of prognosis in aortic regurgitation, predictors of outcome of aortic valve replacement based on this factor have recently been questioned. This study was performed to examine the role of indexes of left ventricular function in predicting the outcome of surgery in patients with aortic regurgitation and left ventricular dysfunction. Fourteen patients with aortic regurgitation with a preoperative ejection fraction of less than 0.55 (average 0.45 +/- 0.02) who underwent aortic valve replacement were studied. The patients had 82 (58%) of a possible 140 predictors of negative outcome preoperatively, but 12 of the 14 patients had a decrease in symptoms and an increase in ejection fraction into the normal range after operation (average postoperative ejection fraction 0.59 +/- 0.04). Although improvement occurred despite the presence of many negative predictors of outcome, there was a significant correlation between postoperative ejection fraction and eight of the tested preoperative predictors. Preoperative end-systolic dimension correlated best (r = -0.91) with postoperative ejection fraction. An end-systolic dimension of 60 mm correlated with a postoperative ejection fraction of 0.55. The results indicate that preoperative ventricular function is still an important determinant of outcome of aortic valve replacement for aortic regurgitation. However, current medical and surgical techniques permit a better prognosis in the presence of reduced ventricular function than was previously considered possible.

Aortic Valve Insufficiency↗
PubMed1987

Lack of apparent effect of assay methodology on the pharmacokinetics of digoxin.

The purpose of this study was to determine if serum digoxin concentration data using three different automated immunoassay methods would produce similar pharmacokinetic values in normal volunteer subjects. Area under the curve (AUC), steady-state volume of distribution/bioavailability ratio (Vd/F), terminal elimination rate constant (beta), clearance/bioavailability ratio (CL/F), maximum digoxin concentration (Cmax), minimum digoxin concentration (Cmin), and time of peak (Tp) were evaluated. Ten healthy volunteers received digoxin capsules 0.2 mg daily for 10 days. On day 10, 16 serial blood samples were collected over a 24-h dosing interval and analyzed by radioimmunoassay (RIA) (Concept 4, Micromedic Systems), fluorescence polarization immunoassay (FPIA) (TDx, Abbott Laboratories), and affinity column-mediated immunoassay (ACMIA), (aca, duPont Instruments). When comparing RIA and FPIA, the mean of the percent differences for AUC, Vd/F, beta, and CL/F were 9, 4, 10, and 6%, respectively. The mean of the percent differences were 2, 3, 44, and 6%, respectively, when comparing RIA and ACMIA. However, none of these differences were statistically significant. Although a trend toward higher Cmax values by RIA was noted, there was no statistical difference in Cmax, Cmin, and Tp. Orthogonal regression of all serum digoxin concentrations showed that FPIA = 0.76 RIA + 0.19, r = 0.967 (p less than 0.001); and ACMIA = 0.92 RIA + 0.04, r = 0.943 (p less than 0.001). At serum digoxin concentrations less than 1 ng/ml, FPIA overestimated RIA results (p less than 0.005), while ACMIA was approximately equal to the RIA results.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1987

Limitations of the long-term clinical application of rate hysteresis.

Rate hysteresis is the ability of a pacemaker to pace at an automatic rate that is different from the escape rate. We reviewed our experience with this programmable feature and its utility. The long-term clinical application of rate hysteresis was limited due to the development of atrial fibrillation or to slowing of the intrinsic cardiac rhythm in 27.6% of the 29 patients. Since many patients with sick sinus syndrome have preserved AV conduction, one might expect that these patients would have an adequate intrinsic heart rate to allow successful use of rate hysteresis pacing mode. Sick sinus syndrome was the intrinsic rhythm disturbance in 63% of the group requiring discontinuation of rate hysteresis. These patients may represent a subgroup in whom any theoretical advantages provided by the rate hysteresis feature may be outweighed by the propensity for the development of atrial fibrillation or significant slowing of the intrinsic rhythm.

Aged↗
PubMed1986

An argument for pacemaker reuse: pacemaker mortality in 169 patients over ten years.

Retrospective examination of 169 consecutive pacemaker patient deaths was done to test the hypothesis that early mortality would preclude full utilization of current battery longevity. We found a 58% mortality within two years of the last generator implant. Nineteen percent occurred within six months, and 38% occurred within a year. This compares to a current clinic of 246 patients where 43% have utilized these pacemakers for greater than 48 months. The age comparison shows that those who died were older than the living controls. The 58% 24-month mortality demonstrates that many patients underutilize expected battery life. The economic implications of pacemaker reuse can then be understood.

Aged↗
PubMed1985

Permanent cardiac pacing in patients on chronic renal dialysis.

We reviewed the need for permanent pacemaker implantation in patients with chronic renal failure who were undergoing dialysis. During a 10-year span, there were seven patients undergoing dialysis in whom a permanent pacemaker was indicated; this was an incidence of 0.68%. During that same period, the general patient population of this hospital had an incidence of permanent pacemaker implantation of about 0.29%. The need for hemodialysis in the same hospital population was 0.51%. Of the seven patients, four had universal pacemakers. Cardiac function was evaluated via radionuclide angiography. Three of the four patients showed improvement with dual-chambered pacing over ventricular pacing. Permanent pacemaker implantation was often needed after initiation of dialysis from 6 to 51 months with a mean of 21 months. During the follow-up period, three patients died from 7 months to 6 years after the institution of permanent pacing; their deaths were secondary to renal disease.

Heart Block↗
PubMed1985

Radionuclide evaluation of dual chamber pacing: comparison between variable AV intervals and ventricular pacing.

We prospectively evaluated changes in left ventricular ejection fraction, end diastolic volume, and stroke volume via radionuclide multigated acquisition study. Comparison was made between ventricular pacing and dual chamber pacing with varying AV intervals. The volumes and changes in ejection fraction were determined at rest, at set increased pacing rates, and during physiological stress. AV sequential pacing shows overall improvement in cardiac function in the majority of patients regardless of left ventricular function. The shorter AV interval would be appropriate for the majority of patients who have an atrial tracking mechanism (adequate intrinsic sensed atrial activity followed by ventricular pacing) and who undergo significant physiological stress.

Aged↗
PubMed1984

Steroid treatment of the painful pacemaker pocket.

Chronic pain about a pacemaker secondary to sterile fibrotic contracture of the capsule is an uncommon but frustrating complication for both the physician and the patient. Three cases of this complication controlled by the late injection of triamcinolone are reported.

Aged↗
PubMed1983

Cardiac pacing under hyperbaric conditions.

Temporary external pacemakers have been reported to fail under hyperbaric conditions. In this study we investigated cardiac pacing under hyperbaric conditions. Permanent hermetically sealed pacemakers were found to function well under hyperbaric conditions, while several models of temporary external pacemakers failed. The electrical characteristics of pacing leads did not change under hyperbaric conditions. External pacing under hyperbaric conditions may be accomplished safely by using a permanent pacemaker attached to the patient's temporary external leads.

Animals↗
PubMed1976

Connections of the nucleus accumbens.

Reports from previous works has given different classifications for the nucleus accumbens. There also appears to be a general lack of information regarding the fiber connections of the nucleus. The present investigation was undertaken to clarify the connections of this structure. Silver impregnation methods were used to discern some of the afferent fibers of the nucleus, and autoradiographic techniques were used to locate target areas of efferent projections. Afferents were found to be predominately from the septum. Other sources of possible afferents were the mid cingulate gyrus and the ventral nucleus of the diagonal band. No argyrophilia was observed in the nucleus accumbens following transection of the fornix body, lesions of the anterior orbital frontal cortex or anterior cingulate gyrus. On the basis of grain counts made from autoradiographic studies, the nucleus accumbens projects predominately to the lateral hypothalamus. Counts above background were found in the cingulate gyrus, septum, ventral nucleus of the diagonal band, midline thalamic nuclei, habenula, caudate and substantia nigra. Thus, efferent projections appear to distribute to both limbic and extrapyramidal structures. Considering these connections and the functions reported by various workers the nucleus accumbens may serve as bridge between limbic and extrapyramidal motor systems effecting limbic influence in some movements.

Animals↗
PubMedDate not supplied

The impact of device recall on patients and family members of patients with automatic implantable cardioverter defibrillators.

BACKGROUND: Patients often depend on life-saving technology as a permanent part of their lives. Sometimes these devices become defective and are recalled. OBJECTIVES: To investigate how the urgent device recall of three models of the Automatic Implantable Cardioverter Defibrillator (AICD) affected confidence in the device and the psychosocial responses of patients and their family member caregivers. METHODS: All patients (N = 31) and caregivers (N = 21) affected by the recall at one heart center completed a survey instrument consisting of a series of visual analog scales designed to measure confidence before and after learning of the recall, fear, anger, depression, anxiety, helplessness, loss of control, uncertainty, and confusion associated with having a recalled AICD. Surveys were completed immediately after being told of the recall and 1 month later. RESULTS: Confidence of patients decreased significantly from a mean of 87% to 74% when comparing perceptions of before learning of the recall to those immediately after (t30 = 3.65, p < 0.0005). For caregivers, mean confidence dropped from 92% to 73% (t19 = 5.0, p < 0.0005). Confidence remained significantly lower 1 month later. Caregiver scores were consistently, although not significantly, higher (less favorable) on the measures of emotional response than patient scores. Caregivers of patients who had received shocks from the AICD and those of patients who had the device for more than a year were generally more affected. CONCLUSIONS: Patient and caregiver confidence in the AICD was significantly reduced. Further research is needed to investigate the trends in the data from caregivers.

Adult↗