Search PubMed⌕ Search

Biomedical subjects

J M Jenkins

Publications and source records attributed to J M Jenkins.

At least 109 records · Page 6Linked to original sources
PubMed1992

The detrimental influence of functional ovarian cysts during in-vitro fertilization cycles.

Reviewing 780 in-vitro fertilization (IVF) cycles, where buserelin was commenced in the preceding luteal phase and human menopausal gonadotrophin on day 4 of the ensuing menses, 53 cycles were identified with sonolucent cysts (30-50 mm diameter). Of the latter 53 cycles, the serum oestradiol was significantly greater on day 4 in 22 cycles abandoned for poor follicular development than in 31 cycles which proceeded to oocyte retrieval (P less than 0.05). Of the 31 cycles proceeding to oocyte retrieval, nine had a day 4 serum oestradiol greater than 200 pmol/l (95th centile for day 4 oestradiol in patients without apparent cysts), and these cycles produced significantly fewer grade 1 embryos than the cycles with day 4 oestradiol levels less than or equal to 200 pmol/l (P less than 0.05). Six of the 53 cycles with cysts resulted in conception, and all of these cycles had a day 4 serum oestradiol less than 200 pmol/l. Among the 53 cycles with ovarian cysts, the serum progesterone on the day of abandonment in four cycles and on the day of human chorionic gonadotrophin administration in one non-abandoned cycle, was above the range established for 104 cycles without cysts. No significant difference was seen in day 4 serum androstenedione levels, and the day 4 serum progesterone was less than 5 nmol/l in all but one patient. Functional activity of ovarian cysts is associated with an adverse influence on IVF cycles.

Androstenedione↗
PubMed1992

Juxtarenal aortic occlusion.

The authors' experience with 113 aortic occlusions in 103 patients during a 26-year period (1965 to 1991) is reviewed. The authors found three distinct patterns of presentation: group I (n = 26) presented with acute aortic occlusion, group II (n = 66) presented with chronic aortic occlusion, and group III (n = 21) presented with complete occlusion of an aortic graft. Perioperative mortality rates were 31%, 9%, and 4.7% for each respective group and achieved statistical significance when comparing group I with group II (p = 0.009) and group I with group III (p = 0.015). Group I presented with profound metabolic insults due to acute ischemia and fared poorly. Group II presented with chronic claudication and did well long-term. Group III presented with acute ischemia but did well because of established collateral circulation. The treatment and expected outcome of aortic occlusion depends on the cause.

Actuarial Analysis↗
PubMed1992

In search of a perfect partnership.

There's no question that our partnership is a natural, given the technological emphasis in modern medicine. My comments are not intended as criticism, but offered in the spirit of broadening our mutual understanding. I believe that open communication will enhance our continued collaboration in this interdisciplinary effort and yield significant advances in medical science.

Algorithms↗
PubMed1992

Ventricular tachycardia detection using bipolar electrogram analysis is site specific.

While algorithms for bipolar intraventricular electrogram analysis have potential use in complementing rate criteria for ventricular tachycardia (VT) detection by implantable antitachycardia devices, the sensitivity of such algorithms to the intracavitary site of electrogram detection has not been determined. In this study, unfiltered (1-500 Hz) electrograms were recorded from a bipolar electrode catheter initially positioned at the right ventricular (RV) apex (site 1) of 12 patients during sinus rhythm (SR1) and during induced monomorphic VT (VT1). Sinus rhythm (SR2) and the identical VT (VT2) were recorded a second time after repositioning the same electrode catheter within the RV apex (site 2) 7-44 mm (mean +/- SD = 15 +/- 10) from its original site. The data were digitized at 1,000 Hz. Templates from SR1 and SR2, respectively, were compared subsequently with individual intraventricular electrograms from 15-25 sec passages of SR1 and VT1 and SR2 and VT2, respectively, using correlation waveform analysis. At site 1, the mean patient correlation coefficient ranged from 0.982-0.998 during SR1 and 0.062-0.975 during VT1. At site 2, the mean patient correlation coefficient ranged from 0.995-0.998 during SR2 and 0.113-0.983 during VT2. Using a correlation threshold of 0.9, VT was differentiated from SR in 11/12 patients (91%) overall: 8/12 patients (67%) at site 1, 9/12 patients (75%) at site 2, and 6/12 patients (50%) at both sites. Thus, while discrimination of VT from SR is feasible with morphological analysis of bipolar right ventricular intracavitary electrograms, the accuracy of bipolar intraventricular electrogram analysis may depend upon intracavitary electrode location in selected patients.

Algorithms↗
PubMed1992

The evolving surgical management of recurrent carotid stenosis.

The traditional approach to recurrent carotid stenosis has been repeat endarterectomy or patch angioplasty. Concern with the durability of repeat carotid endarterectomy has resulted in our use of carotid resection with autogenous graft interposition. This study was designed to determine the outcome and efficacy of carotid resection compared with repeat carotid endarterectomy in the management of recurrent carotid stenosis. From 1974 to 1991, 162 operations (repeat carotid endarterectomy 105, carotid resection 57) were performed for recurrent carotid stenosis. Indication for operation was hemispheric symptoms in 63% of patients, nonlateralizing symptoms in 25%, asymptomatic stenosis in 7%, and previous stroke in 5%. Ninety-one percent of patients had stenosis greater than 90% on arteriography. The perioperative stroke rate for carotid resection was 3.5%, with a subsequent rate of 0.0064 strokes per year. For repeat carotid endarterectomy, the perioperative stroke rate was 1.9% with a subsequent rate of 0.011 strokes per year. Graft patency after carotid resection was 93% (mean follow-up, 35 months). Four patients treated with carotid resection had graft thrombosis, and two of the four remained asymptomatic. After repeat carotid endarterectomy, one patient had carotid thrombosis, and recurrent stenosis greater than 50% developed in 23 patients (mean follow-up, 64 months). Twenty patients treated with repeat carotid endarterectomy underwent an additional operation for further symptomatic recurrent carotid stenosis. We conclude carotid resection is a safe and effective alternative to repeat carotid endarterectomy for patients undergoing operation for recurrent carotid stenosis.

Aged↗
PubMed1991

Effects of increased heart rate and sympathetic tone on intraventricular electrogram morphology.

Electrogram pattern recognition by way of morphologic analysis has been proposed as a technique that may improve discrimination of ventricular tachycardia from sinus rhythm by antitachycardia devices. The potential impact that increases in heart rate and sympathetic tone could have on such techniques, however, has not been previously determined. A comparative study was undertaken to quantify possible changes in ventricular electrogram morphology using correlation waveform, area of difference, and amplitude analyses in 6 patients during atrial overdrive pacing at cycle lengths of 600 and 400 ms (group A), in 13 patients during infusions of physiologic doses of epinephrine (group B), and in 20 patients undergoing infusions of isoproterenol (group C). Four patients were in both groups A and B. A bipolar intraventricular template of cardiac depolarization during sinus rhythm at rest was compared with depolarization during subsequent passages of sinus rhythm at rest and subsequently increased heart rate. In 36 of 39 patients, waveform configuration as assessed by correlation waveform analysis remained relatively stable during atrial overdrive pacing, epinephrine infusion, and isoproterenol infusion when compared with sinus rhythm at rest. The correlation value did not fall below 0.950 in any patient. Area of difference values for the same 36 patients changed by an average of 6 and 37% during atrial overdrive pacing at cycle lengths of 600 and 400 ms intervals, respectively, by 3% during epinephrine infusion, and by 17% during isoproterenol infusion. In these same patients, there was an average change in electrogram amplitude of -1% during atrial overdrive pacing at 600 ms, 26% during pacing at 400 ms, -1% during epinephrine infusion, and 12% during isoproterenol infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The effects of marital disharmony on prepubertal children.

The study investigated the association between marital disharmony and childhood behavior problems in a sample of families drawn from a general population. Eighty-three families where the marital relationship had previously been rated as disharmonious were matched with an equivalent number of families where the marriage was rated harmonious. Mothers, fathers, and children were interviewed, using a semistructured interview format. Children living in disharmonious homes had significantly more problems than children from harmonious homes, and control for confounding variables, such as the mothers' mental health, did not alter this relationship. The main effects found were in antisocial symptomatology. Gender differences and differences according to the accounts of different respondents were found. One possible interpretation is that mothers perceived their sons as more affected by marital disharmony, while evidence from children suggested that boys and girls were equally affected.

Antisocial Personality Disorder↗
PubMed1991

Lack of placental protein 14 production in pregnancy after frozen embryo transfer, down-regulation of anterior pituitary and administration of exogenous oestradiol and progesterone.

The circulating levels of placental protein 14 (PP14) and progesterone were measured in three pregnancies resulting from the transfer of cryopreserved embryos. Two of these women had suppressed ovarian activity as a result of pituitary down-regulation with the luteinizing hormone-releasing hormone agonist (buserelin) prior to treatment with exogenous oestradiol and progesterone. After 14 days of oral oestradiol treatment and if the endometrial thickness was greater than 7 mm, progesterone was given intramuscularly for a further 14 days with embryo transfer on the third day of this treatment. On confirmation of pregnancy by human chorionic gonadotrophin analysis, progesterone administration was altered to transvaginal pessaries for maintenance of adequate progesterone levels and endometrial support. In the two women with ovarian suppression, PP14 levels remained below the 2.5th centile of the normal range for pregnancy. In the third pregnancy, embryo transfer was performed 3 days after a spontaneous luteinizing hormone surge in a normal menstrual cycle. In this pregnancy, PP14 levels were within the normal range. Ultrasonic examination confirmed three normal ongoing singleton pregnancies. These results suggest that the majority of PP14 production in normal pregnancy is under ovarian or anterior pituitary control and that the influence of progesterone is of a secondary nature.

Buserelin↗
PubMed1991

Comparison of 'poor' responders with 'good' responders using a standard buserelin/human menopausal gonadotrophin regime for in-vitro fertilization.

This study identifies a group of 87 patients, who demonstrated a 'poor' response to a standard buserelin/human menopausal gonadotrophin (HMG) regime. The subsequent outcome in 61 of these 'poor' responders when treated with a higher dose of HMG to achieve a satisfactory response was compared with 250 patients, who showed a 'good' response to the standard regime. 'Poor' responders were significantly older than 'good' responders (P less than 0.001), but no significant difference was demonstrated in the indication for in-vitro fertilization (IVF). Even on higher doses of HMG, 'poor' responders took longer for their follicles to achieve maturity than the 'good' responders (P less than 0.01). 'Poor' responders produced 8.9 oocytes per oocyte collection compared to 11.8 in the 'good' responders (P less than 0.01). The fertilization rate was significantly lower in the 'poor' responders compared to the 'good' responders (P less than 0.01). Although there was no significant difference in morphometric grading between 'poor' responder embryos and 'good' responder embryos, the rate of cell division was significantly slower in embryos of the 'poor' responders than the 'good' responders (P less than 0.01). The pregnancy rate per oocyte retrieval was 9% in the 'poor' responders compared to 29% in the 'good' responders (P less than 0.01). The implantation rate in the 'poor' responders was 4.4% compared to 16.1% in the 'good' responders (P less than 0.001).

Adult↗
PubMed1991

Biochemical monitoring during hormone replacement therapy cycles for transfer of cryopreserved embryos in patients with functional ovaries.

Biochemical monitoring was undertaken in 22 treatment cycles for women with normal ovarian function who underwent pituitary suppression with buserelin and administration of exogenous oestradiol (E2) and progesterone (P) for cryopreserved embryo transfer (ET). Eighteen transfers of 1-4 thawed embryos, on the third day of exposure to progesterone, resulted in five clinical pregnancies (27.8%) and one biochemical pregnancy. There was no difference between pregnant and non-pregnant patients in the number and quality of embryos transferred, age, weight or infertility diagnosis. Serum E2 level from days 10-17 (the late proliferative phase) of the therapy cycle were significantly higher in the pregnant group compared with the non-pregnant group (P less than 0.05--P less than 0.005). There were no significant differences in P levels between the two groups from the onset of progesterone administration to the end of the cycle. However, as might be expected, the mean E2/P molar ratio in the pregnant group was significantly higher at the time of ET (P less than 0.02). It is concluded that biochemical monitoring during the embryo replacement cycle is necessary to tailor drug dosages for individual requirements to achieve adequate E2 levels before ET. Alternative routes of oestradiol administration need to be considered in patients with poor E2 profiles.

Buserelin↗
PubMed1991

Evaluating quality, cost-effective health care. Vascular database predicated on hospital discharge abstracts.

This population-based study examines all carotid endarterectomies (CE) performed by all surgeons in a single state over a 10-year period. The methodology is designed to determine morbidity rate, mortality rate, cost, and length of stay, as well as to understand the effect of pre-existing chronic disease, physician, and hospital volume on these outcome variables. The data source consisted of hospital discharge abstract data uniformly collected on all admissions (N = 5.9 million) to acute care hospitals in the state. In the decade 1979 to 1988, 11,199 patients underwent CE. Mortality rate from CE was 2.1%, and the postoperative stroke rate was 3.7% over this period. High physician volume decreased the mortality rate (p less than 0.05) and stroke rate (p less than 0.01) by 50% and significantly (p less than 0.001) reduced hospital cost and length of stay independent of patient complexity. Examination of cost data, adjusted for inflation, showed a decrease in mean cost for CE over the decade. Thus physicians are providing better care for less hospital dollars. Both patient and payor outcome is improved by concentrating CE patients in the hands of high-volume surgeons. Although the data suggests this trend is already evolving, the pace of this evolution can be expected to increase as payors recognize that regionalization of this procedure lowers costs.

Arteriosclerosis↗
PubMed1991

A comparison of four new time-domain techniques for discriminating monomorphic ventricular tachycardia from sinus rhythm using ventricular waveform morphology.

Electrical management of intractable tachycardia via implantable antitachycardia devices has become a major form of therapy. Newly advanced methods of ventricular tachycardia detection propose examination of changes in intraventricular electrogram morphology in addition to or in combination with earlier rate-based detection algorithms. Unfortunately, most of the proposed morphology analysis techniques have computational demands beyond the capabilities of present devices or may be adversely affected by amplitude and baseline fluctuations of the intraventricular electrogram. We have designed four new computationally efficient time-domain algorithms for distinguishing ventricular electrograms during monomorphic ventricular tachycardia (VT) from those during sinus rhythm using direct analysis of the ventricular electrogram morphology. All four techniques are independent of amplitude fluctuations and three of the four are independent of baseline changes. These new techniques were compared to correlation waveform analysis, a previously proposed method for distinction of VT from sinus rhythm. Evaluation of these four new algorithms was performed on data from 19 consecutive patients with 31 distinct monomorphic ventricular tachycardia morphologies. Three of the algorithms performed as well or better than correlation waveform analysis but with one-tenth to one-half the computational demands.

Aged↗
PubMed1991

Computer analysis of the electrocardiogram during esophageal pacing cardiac stress.

It has been estimated that 15 to 30% of patients with suspected or known coronary artery disease are unable to perform an adequate exercise stress test due to a variety of reasons such as obesity, poor physical condition, claudication, etc. Transesophageal atrial pacing has been proposed as a noninvasive alternative for inducing cardiac stress in patients who cannot exercise. Although computer analysis is commonly employed to analyze the electrocardiogram (ECG) during the conventional exercise stress test, the surface ECG recorded during transesophageal atrial pacing is contaminated with large pacing artifacts which confound beat identification by standard computer software. We report the development of a robust signal processing algorithm for interpretation of the surface ECG during transesophageal atrial pacing stress. The algorithm employs novel schemes using both linear and nonlinear transformations to detect and differentiate between the pacing artifact and QRS complex even in difficult situations where the pacing artifact is in proximity to or superimposed on the QRS complex. The algorithm uses sophisticated logic for automatic recognition of sustained capture. It subsequently calculates beat-by-beat and average (over five beats) ST segment amplitude and slope. The algorithm also reports the instantaneous heart rate, RR interval, pace-to-R interval, R-wave amplitude, and estimated sinus node recovery time upon loss of sustained capture. The limitations of present exercise ECG computer methods in processing the ECG during transesophageal atrial pacing stress are evaluated and significantly improved performance by our algorithm is demonstrated.

Adult↗
PubMed1991

Marital disharmony and children's behaviour problems: aspects of a poor marriage that affect children adversely.

The aim of this study was to investigate the elements of the parental marital relationship which put children at risk for behavioural and emotional problems. Data from 119 families from the general population with a child aged between 9 and 12 years were analysed for the present study. The relationship between children's emotional and behavioural problems and overt parental conflict, covert tension between parents and discrepancy on child-rearing practices was assessed. Overt parental conflict was found to relate most strongly to children's emotional and behavioural problems using mothers', fathers' and children's accounts of the children's symptoms and after controlling for other aspects of marital disharmony. Aspects of the parent-child relationship were hypothesized as mediating variables in the relationship between parental conflict and children's emotional and behavioural problems, but the data did not support this hypothesis.

Adaptation, Psychological↗
PubMed1991

Impact of filtering upon ventricular tachycardia identification by correlation waveform analysis.

Signal analysis of digitized waveforms has been postulated as a method for improving sensitivity and specificity of ventricular tachycardia (VT) detection in implantable antitachycardia devices. Such improvement may alleviate the problem of unwarranted delivery of therapy by adding precision to the identification of the pathological VT. Morphological analysis could also allow distinct therapies to be initialized for multiple VTs in the same patient. Correlation waveform analysis (CWA) has been demonstrated to be effective in separating benign rhythms from VT in wideband recordings (1-500 Hz) but the effect of filtering has not been previously examined. Bipolar (1 cm) intraventricular recordings (1-500 Hz) of sinus rhythm (SR) and 25 distinct VTs in 18 patients were analyzed by CWA using a signal-averaged SR template. Passages contained 65.9 +/- 19.8 VT depolarizations (range 45-108). Digital filtering was performed on all data passages with varying passbands. Results for passages with a bandwidth of 1-250 Hz were equivalent to wideband results, i.e., greater than or equal to 92% paired sets of SR and VT were separable at a 95% confidence level. A bandwidth of 1-100 Hz decreased discrimination to 84%. At a bandwidth of 1-80 Hz, 80% of cases were successfully separated, but at 10-80 Hz these results improved to 88%. Bandwidths of 20-80 and 30-80 Hz reduced reliability of CWA performance to 72% and 60%, respectively. Filtering at typical pacemaker/defibrillator passbands produced morphological analysis results equivalent to those yielded at wideband settings. Differences in the range between SR versus VT decreased in filtered recordings but overall detection of VT was not degraded.

Algorithms↗
PubMed1991

Identification of ventricular tachycardia using intracardiac electrograms: a comparison of unipolar versus bipolar waveform analysis.

Implantable antitachycardia devices suffer a high false-positive rate of delivery of therapy because current detection schemes based upon ventricular rate and rate variations are excessively sensitive at the cost of specificity. Several methods have been proposed for providing complementary information derived from morphologic analysis of intraventricular electrograms in order to increase specificity. The majority of these techniques have utilized bipolar electrogram analysis to detect changes in ventricular activation indicative of ventricular tachycardia. Whether bipolar or unipolar intracardiac electrogram analysis might be preferred for discriminating ventricular tachycardia from sinus rhythm has not been determined. In this study, a previously demonstrated method for identification of ventricular tachycardia using intracardiac electrograms, correlation waveform analysis, was used to analyze both unipolar and bipolar signals during sinus rhythm and ventricular tachycardia recorded during electrophysiology studies of 15 patients with inducible sustained monomorphic ventricular tachycardia. Correlation waveform analysis consistently discriminated between all depolarizations during ventricular tachycardia in 14/15 patients (93%) using either electrogram configuration; 13 of the 14 patients were common to both groups. Of these patients, 8/15 (53%) had greater separation between sinus rhythm and ventricular waveforms with bipolar electrogram analysis while 7/15 (47%) had greater separation with unipolar electrogram analysis. We conclude that morphologic analysis of unipolar and bipolar electrograms may be equally effective in distinguishing ventricular tachycardia from sinus rhythm. For individual patients, either a unipolar or bipolar ventricular configuration may be preferable, and should be chosen on a patient-specific basis during electrophysiology study prior to antitachycardia device implantation.

Adult↗
PubMed1991

A time-domain analysis of intracardiac electrograms for arrhythmia detection.

The analysis of intracardiac electrogram morphology has been proposed as a complementary method for accurate discrimination between sinus rhythm (SR), supraventricular dysrhythmias, and ventricular dysrhythmias by automatic antitachycardia and cardioverter defibrillator devices. In this study, the performance of a traditional time-domain method for surface electrocardiogram interpretation--Correlation Waveform Analysis (CWA) and a newly developed technique--Bin Area Method (BAM) were used to analyze unfiltered intraatrial and intraventricular electrograms obtained from 47 patients during routine cardiac electrophysiology studies. Nineteen patients had 31 distinct, sustained, monomorphic ventricular tachycardias (VTs) induced; 13 patients had paroxysmal bundle branch block of supraventricular origin (BBB) induced; 19 patients had retrograde atrial activation during ventricular overdrive pacing. Three patients were common to two or more groups. Using a best fit electrogram alignment, both CWA and BAM distinguished VT from SR in 28/31 cases (90%), BBB from SR in 15/15 patients (100%), and anterograde from retrograde atrial activation in 19/19 patients (100%). We conclude that the use of time-domain techniques that are independent of amplitude and baseline fluctuations appear to be reliable for discrimination of retrograde atrial activation, paroxysmal BBB, and VT from SR using intracardiac electrograms. Reduction of computational time and power constraints, without sacrificing reliable dysrhythmia discrimination, is possible. These features may make real-time morphology analysis of intracardiac electrograms feasible for automatic antitachycardia and cardioverter-defibrillator devices.

Algorithms↗