Estrogen replacement reverses endothelial dysfunction in postmenopausal women.

PURPOSE: To measure the effect of long-term clinical hormone replacement therapy on brachial artery vasomotor responses, and to compare these responses in premenopausal and postmenopausal women. PATIENTS AND METHODS: We studied 23 postmenopausal women, including 18 who were evaluated prior to starting clinically indicated oral hormone replacement therapy. Twelve postmenopausal women received estrogen alone, the other 6 were treated with estrogen/medroxyprogesterone combinations. Eleven premenopausal volunteers served as a comparison group. Change in brachial artery diameter in response to postischemic hyperemic flow and sublingual nitroglycerin was measured by ultrasound. RESULTS: The 18 postmenopausal subjects receiving hormone replacement showed a progressive improvement in their postischemic vasodilation. Mean (+/-SD) postischemic vasodilation was 0.4%+/-7.1% prior to estrogen replacement. There were significant increases in postischemic vasodilation of 4.8%+/-6.6% after 1 month and 8.3%+/-3.4% after 6 months of estrogen replacement. The response to nitroglycerin was similar at all time points studied. Women with the most abnormal responses to hyperemic flow at baseline demonstrated the greatest improvement after 6 months of hormone replacement therapy. Premenopausal and postmenopausal subjects differed in their response to hyperemic flow, with premenopausal women showing 5.8% vasodilatation compared with a 0.6% vasodilation in postmenopausal women (P=0.046). CONCLUSIONS: Endothelial function is abnormal in many postmenopausal women compared with premenopausal women, and in some postmenopausal women it can be enhanced by estrogen replacement therapy. This effect may increase with prolonged use.

A comparison of the dual lumen and coaxial catheters for temporary hemodialysis access.

Percutaneous central venous catheterization can provide reliable temporary hemodialysis access. The current study compared the hemodynamic performance of 28 coaxial catheters to 27 side by side catheters. A total of 675 dialysis sessions were evaluated to assess the flow characteristics of these two designs. The results demonstrated that the side by side catheter provided greater cumulative blood flow with more favorable venous and arterial pressures. Nevertheless, the coaxial catheter performed satisfactorily and met the minimum standards for these devices.

Technical results from the eversion technique of carotid endarterectomy.

A total of 167 carotid endarterectomies by the eversion technique were completed in 158 patients at a teaching hospital during the 6-year period ending July 1995. The average patient age was 66 years with a range of 39 to 89 years, and 99 (63%) were male. General anesthesia was employed routinely, and temporary indwelling shunts, were not used. Indications for endarterectomy included hemispheric transient ischemic attack (43), amaurosis fugax (20), stroke (41), and asymptomatic stenosis (63). Associated patient risk factors were not significantly different for men and women, and included diabetes mellitus (22%), tobacco abuse (72%), hypertension (69%), hypercholesterolemia (76%), cardiac disease (54%), and renal disease (21%). One (0.6%) permanent operative stroke and two (1%) 30-day hospital deaths occurred. Vascular laboratory follow-up was accomplished by duplex scanning with a documented sensitivity of 98 per cent in detecting a > or = 40 per cent stenosis. Eighty-nine per cent (148) of the 167 endarterectomies were tested at least once postoperatively. Overall laboratory follow-up averaged 17 months and ranged from one to 69 months. Residual stenosis, included perioperative thrombosis, occurred in 8 (5%) arteries. Recurrent stenosis was detected in four (2%) cases at 9, 24, 54, and 66 months after endarterectomy. Statistical analyses failed to implicate any specific patient risk factor, age, sex, or operative indication relevant to recurrent stenosis. Residual stenosis was correlated with younger patient age (P = 0.002), female gender (P = 0.12), and endarterectomy on the right side (P = 0.008). Carotid eversion endarterectomy appears to be a universally applicable, safe, and durable operative technique.

Groin lymphorrhea complicating revascularization involving the femoral vessels.

Seven (4%) of 193 patients developed lymphoceles in 8 (2%) of 316 groin wounds after 211 arterial reconstructive procedures. Included were 91 aortic, 15 extra-anatomic, and 105 infrainguinal revascularizations. Lymphoceles developed in otherwise uncomplicated wounds in 6 (8%) of 73 patients with oblique incisions and bilaterally in 1 (1%) of 120 patients with vertical incisions (p = 0.01). This difference may be related to the surgical technique, with increased lymphatic damage and inadequate wound closure in the oblique approach. No increased incidence of lymphorrhea was noted in those patients undergoing aortic reconstruction regardless of the type of incision used (p = 0.15), or when compared with patients who had undergone extra-anatomic or infrainguinal bypass (p = 0.14). Each lymphocele was persistent, and external fistulas spontaneously occurred in three. Diagnosis was based upon clinical awareness and the appearance of the groin mass. Conservative management was uniformly unsuccessful, and operative ablation of the lymph fistula and lymphocele proved to be definitive therapy.

Efficacy of the supraclavicular route for temporary hemodialysis access.

The percutaneous supraclavicular approach for temporary central venous hemodialysis access was successfully used in 27 of 34 cases (79%) without significant complications and was found to be a durable technique acceptable to every patient. The supraclavicular site was used from 3 to 156 days (mean, 40 days). The average catheter life was 25 days, and 13 guidewire catheter changes among eight patients were required for catheter limb thrombosis or suspected infection. Preventable kinks resulting from technical error occurred in two catheters (5%), necessitating guidewire replacement in one. A total of 41 catheters were used, and infection was documented in one (2%). Catheters were intentionally removed in 21 patients and were removed for proved infection (1) or suspected infection (5) in the remaining six patients. No new clinical evidence of central venous stenosis or thrombosis, such as arm swelling, prominent cutaneous collateral veins, or increased venous pressure at dialysis, was observed. We suggest the supraclavicular approach as the primary route for temporary central venous hemodialysis access. Continued follow-up is necessary to substantiate the initial favorable experience with the supraclavicular technique.

Intense source of spin-polarized electrons.

Spin angular momentum conservation in chemiionization reactions involving optically oriented He(2(3)S) atoms in a flowing helium afterglow has been exploited to yield a source of spin-polarized electrons. Either transversely or longitudinally polarized electrons can be extracted. Polarized electron beam currents of approximately 2 muA have been realized at 40% polarization. The beam has an effective emittance of approximately 2 mrad/cm over the energy range 100-400 eV, an energy spread of less, similar0.15 eV, and the polarization is readily reversible. The source is relatively inexpensive and appears suitable for the majority of low-energy spin-dependent scattering experiments proposed to date.

Mott electron spin polarization analysis system of novel design.

A novel Mott polarization analysis system is described. This system is much simpler than earlier designs and offers improved rejection of electrons inelastically scattered from the gold target foil. In addition the analyzer is capable of ''in-line'' polarization measurements.