Circumferential hymen elasticity. A marker of physiologic maturity.

OBJECTIVE: To study the relationship between anatomic changes in the peripubertal female and sex hormonal maturation. STUDY DESIGN: Medical records were reviewed on virginal females whose first gynecologic examination occurred between ages 9 and 20 and who were examined at least twice by the same gynecologist. Speculum sizes at each visit were surrogate measures of circumferential hymenal elasticity, the anatomic change of interest. RESULTS: Mean ages at the two visits for the 35 patients were 14.6 and 16.7 years, respectively, with substantial overlap in ages between visits. Average Tanner breast and pubic hair stages and speculum sizes were greater at the second visit (P < .001). At first visit, age, Tanner breast and pubic hair stages, and time elapsed from menarche, thelarche and pubarche correlated positively with larger speculum sizes (P < .10). Change in speculum size between visits was associated with younger age and lower Tanner pubic hair stages at first visit and with increases between visits in age, body mass index and Tanner pubic hair stages. Larger changes were associated with shorter elapsed time between the first visit and menarche, thelarche and pubarche. CONCLUSION: Circumferential hymenal elasticity increases during adolescence. This anatomic change, the surrogate measure of which is specula diameter, can be used along with Tanner staging as a measure of physiologic maturity in adolescent women.

Factors associated with successful implantation of nonthoracotomy defibrillation lead systems.

Two hundred forty-three consecutive patients underwent attempted implantation of nonthoracotomy defibrillation lead (NTL) systems. The importance of clinical and lead-related factors were analyzed regarding their relation with implantation failure caused by an unacceptably high defibrillation threshold (DFT). Overall, 33 (14%) of 243 patients failed NTL implantation. Patients undergoing attempted implantation of NTL systems with monophasic shock waveforms (monophasic group, n = 145) had an incidence of failed implantation of 22% (n = 32) versus an incidence of 1% (n = 1) among patients undergoing attempted implantation by using biphasic shock waveforms (biphasic group, n = 98; odds ratio, 26.9; p < 0.001). The incidence of success and simplicity of implantation of NTL systems was markedly improved in patients undergoing NTL implantation by using biphasic shock waveforms. Clinical factors could be used to stratify patients in the monophasic group for their risk of implantation failure. In the biphasic group, no clinical factor could be correlated with a low DFT with a fully endovascular system.

Idiopathic right ventricular outflow tract tachycardia: narrowing the anatomic location for successful ablation.

Pace mapping used to locate the site for ablation of idiopathic right ventricular outflow tract (RVOT) ventricular tachycardia remains difficult and time-consuming. A method to facilitate pace mapping and the most common site of ablation of this tachycardia are reported. In 18 consecutive patients with RVOT ventricular tachycardia, electrocardiographic criteria based on the QRS orientation in lead 1 and the R wave progression in the precordial leads were used to find pace maps matching the arrhythmia. Identical pace maps were obtained on the septum of the RVOT in 16 patients and resulted in successful ablations. These sites were concentrated in the anterior superior aspect of the RVOT determined by fluoroscopic imaging. In the remaining two cases identical pace maps could not be found in this area. The results of this study narrow the anatomic location for radiofrequency ablation of idiopathic RVOT ventricular tachycardia. This is the first description of an electrocardiography-guided approach to finding an identical pace map in the RVOT.

Utility of the 12-lead electrocardiogram in localizing the origin of right ventricular outflow tract tachycardia.

The purpose of this investigation was to develop an algorithm on the basis of the QRS morphology observed on the 12-lead ECG that would rapidly locate the site of origin of the monomorphic ventricular tachycardia arising from the septal portion of the RVOT. Radiofrequency catheter ablation guided by pace-mapping techniques has proven effective in eliminating the ventricular tachycardia originating from the RVOT in the absence of structural heart disease. A method that would rapidly identify the portion of the RVOT septum toward which more detailed pace-mapping should be directed before catheter ablation would be useful in decreasing procedure time and radiation exposure and potentially facilitating a successful ablation procedure. The RVOT septum was divided into nine sites. In 11 patients, bipolar pacing was performed at each of the nine designated sites to mimic ventricular tachycardia. A standard 12-lead surface ECG was recorded during pacing. The QRS morphology in the limb leads was characterized and the site of the R-wave transition was determined in the precordial leads. A QS in lead a VR and a monophasic R wave in leads II, III, aVF, and V6 were noted in each patient at all paced sites. In lead I, pacing at the three posterior septal sites always resulted in an R wave. Pacing at the three anterior sites produced a dominant Q wave (either QS or Qr) at 17 (52%) of 33 sites or a qR complex at 16 (48%) of 33 sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Benefits and lessons learned from stored electrogram information in implantable defibrillators.

Implantable defibrillators have evolved from simple event counters to sophisticated diagnostic monitoring units capable of storing electrocardiographic information surrounding arrhythmia events and device therapy. In this review, the nature and characteristics of these stored electrocardiographic recordings are discussed and examples displayed. Potential benefits and limitation of stored electrogram analysis are described with respect to both clinical utility and the ability to enhance our understanding of ventricular arrhythmogenesis. Finally, future developments to improve data storage, retrieval, and analysis are identified.

Postoperative lead-related complications in patients with nonthoracotomy defibrillation lead systems.

OBJECTIVES: This study sought to document postoperative complications attributable to nonthoracotomy defibrillation lead systems in a large cohort. BACKGROUND: The incidence of postoperative complications specifically associated with nonthoracotomy defibrillation lead systems is unknown. METHODS: Postoperative lead-related complications were evaluated in 170 patients with a nonthoracotomy defibrillation lead system who were followed up for a mean (+/- SD) of 17 +/- 12 months. Each system incorporated one or more intravascular leads. In 117 patients (69%), the system incorporated a subcutaneous defibrillation patch. All implantations were performed in an operating room by cardiothoracic surgeons. Defibrillation thresholds were measured at implantation, before hospital discharge (mean 3 +/- 2 days) and at 4 to 18 weeks after implantation. Patients were evaluated every 2 to 3 months after implantation or as indicated by clinical exigency. RESULTS: Twenty-seven patients (15.9%) were diagnosed with a lead-related complication that either extended the initial hospital period or led to a second hospital admission. Complications included endocardial lead or subcutaneous defibrillation patch dislodgment in eight patients (4.7%), which was diagnosed between 2 and 345 days after implantation; endocardial or subcutaneous patch lead fracture in six (3.5%), which was diagnosed between 53 and 600 days after implantation; subcutaneous patch mesh fracture in one, which was diagnosed at 150 days after implantation; subclavian vein thrombosis in three (1.8%), which was diagnosed at 2 to 50 days after implantation; and unacceptably elevated defibrillation threshold (within 5 J of maximal device output) in nine (5.3%), which was documented at one of the two postimplantation evaluations in eight patients or at the time of failure to terminate a spontaneous ventricular tachycardia in one. Seventeen of the 27 patients required reoperation for correction of their complication. In addition, system infection requiring complete explantation occurred in seven other patients (4.1%) at an interval from implantation ranging from 14 to 120 days. CONCLUSIONS: Postoperative complications related to a nonthoracotomy defibrillation lead system were common and frequently required reoperation for correction. The rate of system explantation due to infection was also significant. Postoperative defibrillation testing and vigilant outpatient follow-up evaluation are necessary to ensure normal lead function.

Comparison of initial detection and redetection of ventricular fibrillation in a transvenous defibrillator system with automatic gain control.

OBJECTIVES: The purpose of this study was to prospectively evaluate postshock redetection of ventricular fibrillation by a system that coupled an implantable cardioverter-defibrillator with an automatic gain control sense amplifier and a transvenous lead system. BACKGROUND: Redetection of ventricular fibrillation after an unsuccessful first shock has not been systematically evaluated. Previous studies have suggested that sensing performance of some lead systems may be adversely affected by the delivery of subthreshold shocks. METHODS: The time required for both initial detection and redetection of ventricular fibrillation was compared in 22 patients. These times were estimated by subtracting the capacitor charge time from the total event time. RESULTS: A total of 113 successful and 57 unsuccessful initial shocks were delivered during induced ventricular fibrillation. The mean +/- SD initial time to detection of ventricular fibrillation was 5.5 +/- 1.7 s (range 2.4 to 10.8); the time to redetection ranged from 1.5 to 18.5 s (mean 4.5 +/- 2.8, p = NS vs. detection time). Abnormal redetection episodes, defined as a redetection time > 10.2 s (i.e., > 2 SD above the mean redetection time), were observed in 4 (18%) of 22 patients. CONCLUSIONS: Redetection of ventricular fibrillation after a subthreshold first shock may be delayed. Device testing with intentional delivery of subthreshold shocks to verify successful postshock redetection of ventricular fibrillation should be performed routinely in all patients.

Temporal segregation in signalling: a novel mechanism in human neutrophils.

The ability of neutrophils to carry out chemotaxis in response to low chemoattractant concentrations, but arrest their motility when exposed to higher concentrations of the same substance, has fascinated investigators for years. By analyzing the temporal characteristics of the morphological responses, corresponding to chemotaxis and cell arrest, we have recently discovered that the choice between them is made by transduction of the continuous binding process into either single or multiple stimuli within defined time intervals, initiating chemotaxis or cell arrest, respectively. Both experimental and theoretical lines of evidence are presented to support the validity of this unique mechanism.

Cardiac output measurements for guidance of perioperative intravenous hydration in an obstetric patient.

The administration of regional anesthesia to women with moderately severe and severe pre-eclampsia is commonly preceded by intravenous hydration guided by central venous pressure (CVP) monitoring. We are reporting the case of a gravida with incipient HELLP syndrome whose fluid management before, during, and after cesarean section under continuous extradural block was guided by non-invasive cardiac output measurements.