Recommendations for eligibility criteria concerning bariatric and metabolic surgical and endoscopic procedures for obese Hong Kong adults 2024: Hong Kong Society for Metabolic and Bariatric Surgery Position Statement.

The surgical management of obesity in Hong Kong has rapidly evolved over the past 20 years. Despite increasing public awareness and demand concerning bariatric and metabolic surgery, service models generally are not standardised across bariatric practitioners. Therefore, a working group was commissioned by the Hong Kong Society for Metabolic and Bariatric Surgery to review relevant literature and provide recommendations concerning eligibility criteria for bariatric and metabolic interventions within the local population in Hong Kong. The current position statement aims to provide updated guidance regarding the indications and contraindications for bariatric surgery, metabolic surgery, and bariatric endoscopic procedures.

Comparative assessment of water quality parameters of mariculture for fish production in Hong Kong Waters.

The objective of the study is to evaluate the effect of fish cultivation on water quality in fish culture zone (FCZ) and analysed by Principle Component Analysis (PCA). 120 surface water samples were collected from Hong Kong Waters (60 samples in Victoria Harbour and another 60 in Ma Wan FCZ). Significant difference was found in dissolved oxygen (MW: 59.6%; VH: 81.3%), and Escherichia coli (MW: 465 CFU/100 ml; VH: 162.5 CFU/100 ml). Three principle components are responsible for water quality variations in the studying sites. The first component included E. coli (0.625) and dissolved oxygen (0.701). The second included E. coli (0.387) and ammonical-nitrogen (0.571). The third included E. coli (0.194) and ammonical-nitrogen (0.287). This framework provides information to assess the relative contribution of eco-aquaculture to nutrient loads and the subsequent risk of eutrophication. To conclude, a rigorous monitoring of water quality is necessary to assess point and nonpoint source pollution. Besides, appropriate remediation techniques should be used to combat water pollution and achieve sustainability.

Micro-engineered remote palpation device for assessing tissue compliance.

This paper concerns the operation of the actuator for a prototype micro-engineered mechanical palpation device for deployment via a cystoscope to measure the dynamic mechanical properties of the prostate gland in vivo. The subassembly consists of a 400x200 microm silicon (Si) piston manufactured using deep reactive ion etching (DRIE) housed within an anodically bonded glass-Si-glass sandwiched housing. The micro-channel on the Si layer was formed by powder blasting and contains the micro-piston with one end pointing to the side of the housing and the other facing a via hole leading to a capillary tube. The opening on the side of the housing was sealed by a 5 microm thick silicone membrane which acts to retain the micro-piston and act as a return spring. A 320 microm diameter capillary forms the connection between the micro-channel and a micro-syringe which is operated by a programmable syringe pump to produce a reciprocating action. A pressure sensor is connected along the capillary tube to measure the dynamic pressure within the system. The micro-piston has already been used, separately actuated to measure the dynamic mechanical properties of known viscoelastic materials and prostate tissue. The purpose of the present work is to assess the functionality of the actuator assembly.

Solid-phase extraction-fluorimetric high performance liquid chromatographic determination of domoic acid in natural seawater mediated by an amorphous titania sorbent.

The feasibility of using sol-gel amorphous titania (TiO2) as a solid-phase sorbent for the pre-concentration of domoic acid (DA), a potent amnesic shellfish poisoning (ASP) toxin, directly from seawater was explored. The sol-gel titania material is able to adsorb DA from seawater, via the formation of ester-linkage between the carboxylic moieties of DA and the Ti-OH groups on the sorbent surface, at low pH and desorb it at high pH. The chemisorption process is not significantly interfered by the seawater matrix. The optimum pH values for the adsorption and desorption of DA were found to be pH 4 and 11, respectively. The optimal sorbent loading for the batch-type solid-phase extraction of DA was 0.67 mg-TiO2 ng-DA(-1) and adsorption equilibrium was achieved in 2 h at room temperature. The desorbed DA in 500 microL of 0.1 M alkaline borate buffer can be directly derviatized by 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) in aqueous media for fluorimetric HPLC quantification. Analyte recovery, repeatability and detection limit of this titania SPE-fluorimetric HPLC determination are 89%, 6.2% and 120 pg-DA mL(-1) (n=7, P<0.05), respectively, for a sample volume of 30 mL. This titania SPE technique should also be applicable to the pre-concentration of other polar carboxylate- and phosphonate-containing biomolecules and pharmaceuticals in complex and interfering environmental sample matrices.

Design and development of the pressure ulcer nursing information system for clinical risk management.

Since 2002, hospitals have to report to Nursing Service Department, Hospital Authority Head Office on the pressure ulcer trends for risk management in Hong Kong. In line with the strategy, hospitals have designed their own patient observation records and reporting forms for monthly analysis and reporting of in-patient hospital acquired pressure ulcers. The incidence rates of individual hospital and its specialties are then calculated manually or using electronic spread sheets. However, the diversity in data definition and vocabulary use generates difficulties in communication among professionals and hospital managers. The development of the system would help to standardize the requirements and to reduce the time required for generating trends and ulcer information. The system also lays the foundation for future systems integration with the changing information system infrastructure.

In-vitro dynamic micro-probing and the mechanical properties of human prostate tissues.

In vitro macro- and micro-indentation test systems have been designed to measure the dynamic micro-mechanical properties of human prostate tissues at actuation frequencies between 5 Hz and 30 Hz, and 0.5 Hz and 20 Hz, respectively. The development of in vitro test systems was aimed at assessing the capacity of such an in vivo medical probe to provide information useful for the diagnosis of various prostate diseases. The macro-indentation test system is an established one, which we have used to determine structure-property relationships in human and canine prostate tissues and here we use it to validate a newly-developed micro-indentation test system using a tissue phantom. Mechanical testing was also carried out on sections of prostate tissue harvested from cystectomy and radical prostatectomy, diagnosed with bladder cancer and benign prostatic hyperplasia. Dynamic probing under displacement control was carried at pre-strains between 5% and 8% for macro-probing and at 5% pre-strain for micro-probing, and the general effect of pre-strain on the dynamic mechanical properties (described by the amplitude ratio between stress and strain, and the phase lag between strain and stress) of phantom and prostate tissues is presented. Specific point probing on epithelial and stromal histological components was also carried out showing a significant difference between the amplitude ratios of epithelial and stromal components for actuation frequencies exceeding 5 Hz. However, no significant difference was found between phase lags for epithelial and stromal tissues.

MicroAlbuminuria Prevalence Study (MAPS) in hypertensive type 2 diabetic patients in Hong Kong.

OBJECTIVES: To assess the prevalence of macroalbuminuria and microalbuminuria, and the level of blood pressure control in patients with type 2 diabetes and hypertension in Hong Kong. DESIGN: Cross-sectional clinic-based epidemiological study. SETTING: Six medical centres (including two public hospital diabetes centres) in Hong Kong. PATIENTS: Recruited from the medical centres from April to November 2002, after excluding those with bacteriuria and haematuria. MAIN OUTCOME MEASURES: Body mass index; blood pressure; levels of blood glucose, macroalbuminuria, and microalbuminuria; treatments for hypertension and diabetes. RESULTS: The as per-protocol recruited population of 437 hypertensive type 2 diabetic patients had a mean age of 61.7 (standard error, 0.5) years. Overall, the prevalence of diabetic nephropathy in this population was high; 18.3% had macroalbuminuria (95% confidence interval, 16.5-20.2%) and 24.9% had microalbuminuria (95% confidence interval, 22.9-27.0%). Predictive factors were advanced age, male sex, poor blood pressure control, and existing cardiovascular complications. Whilst almost all patients (96.1%) were receiving treatment for hypertension, only 25.6% had systolic/diastolic blood pressures below the 130/85 mm Hg target. CONCLUSIONS: In Hong Kong, the prevalence of microalbuminuria and macroalbuminuria is high in type 2 diabetic patients with hypertension, particularly in males and those with poorly controlled systolic blood pressure. Tight glycaemic control, antihypertensive therapy, and use of renin-angiotensin system inhibitors/blockers are necessary to retard the progression of nephropathy to advanced renal disease.

Reversible impairment of left and right ventricular systolic and diastolic function during short-lasting atrial fibrillation in patients with an implantable atrial defibrillator: a tissue Doppler imaging study.

AF with a fast ventricular response may cause ventricular mechanical impairment, though whether short-lasting AF with satisfactory rate control may affect ventricular function is unknown. This study investigated if prompt cardioversion by an implantable atrial defibrillator (IAD) may prevent left (LV) and right ventricular (RV) systolic and diastolic dysfunction. Ten patients (mean age 61 +/- 9 years, 8 men) with paroxysmal AF without structural heart disease who received an IAD were studied by echocardiography and tissue Doppler imaging (TDI) for both ventricles. Measurements were made during baseline sinus rhythm and at 1-minute, 20-minute, 4-hour, and 1-week postcardioversion of an episode of spontaneous AF. The occurrence of AF and the ventricular rate were monitored at 2-hour intervals by the device. There were 50 episodes of AF with a mean duration of 8.8 +/- 8.9 days (2 hours to 37 days). There was no difference in M-mode measured LV fractional shortening and ejection fraction between baseline sinus rhythm and after cardioversion. However, the TDI derived myocardial systolic velocity (TDI-S) was significantly lower at 1-minute postcardioversion and was normalized at 1 week in both LVs (baseline: 5.7 +/- 1.8, 1 minute: 4.2 +/- 1.0, 20 minutes: 4.3 +/- 0.9, 4 hours: 4.8 +/- 1.0, 1 week: 5.5 +/- 1.8 cm/s; P < 0.005 when comparing 1 minute and 20 minutes to baseline; P < 0.05 when comparing 4 hour to baseline) and RV (baseline: 10.4 +/- 2.1, 1 minute: 7.8 +/- 1.4, 20 minutes: 8.1 +/- 1.2, 4 hours: 9.2 +/- 1.5, 1 week: 10.0 +/- 2.0 cm/s; P < 0.005 when comparing 1 minute, 20 minutes, and 4 hours to baseline). For diastolic function, transmitral Doppler study showed a decrease in early filling velocity at 1 minute (P < 0.05) and 20 minutes (P < 0.005), which was normalized at 4 hours. There was no change in transtricuspid Doppler flow. However, TDI derived myocardial early filling velocity was decreased in the LV (baseline: 6.0 +/- 2.8, 1 minute: 5.4 +/- 2.3, 20 minutes: 5.4 +/- 2.1, 4 hours: 6.1 +/- 2.2, 1 week: 5.8 +/- 1.7 cm/s; P < 0.05 when comparing 1 minute and 20 minutes to baseline) and RV (baseline: 8.9 +/- 3.5, 1 minute: 7.9 +/- 3.3, 20 minutes: 8.1 +/- 3.3, 4 hours: 8.5 +/- 2.9, 1 week: 8.4 +/- 3.5 cm/s; P < 0.05 when comparing 1 minute to baseline). AF of a longer duration (> 48 hours) resulted in a more depressed TDI-S in LV (> 48 hours: 4.2 +/- 1.0, < or = 48 hours: 5.3 +/- 1.3 cm/s; P < 0.01). Shocks in sinus rhythm did not affect any of the above echocardiographic parameters. Therefore, despite adequate rate control, short-lasting AF impairs systolic and diastolic function in both ventricles, which improves gradually after cardioversion. Early restoration of sinus rhythm by an IAD minimizes ventricular dysfunction. TDI is a sensitive tool to assess early systolic and diastolic dysfunction.

Comparison of MB/BacT system and agar proportion method in drug susceptibility testing of Mycobacterium tuberculosis.

The drug susceptibilities of 105 isolates/strains of Mycobacterium tuberculosis (101 clinical isolates and four control strains from the American Type Culture Collection) were assessed by the MB/BacT system and conventional agar proportion method. The agreement rates between the two methods were 99.0% for streptomycin, 95.2% for isoniazid and 100% for rifampin. The mean times to detection for drug-resistant isolates were 4.7 days (range: 2.5-13.7 days) using the MB/BacT system and 14.8 days (range: 14-21 days) using the agar proportion method. For drug-susceptible isolates, the times to detection were 10.8 days (mean) and 21 days respectively. Thus, these data have demonstrated that the automated, non-radiometric MB/BacT system is an efficient, accurate and reliable method for assessing drug susceptibilities of M. tuberculosis compared with the conventional agar proportion method.

A cephalic vein cutdown and venography technique to facilitate pacemaker and defibrillator lead implantation.

The aim of this study was to assess the feasibility of a cephalic vein cutdown and venography technique for implantation of a pacemaker or ICD and to determine the causes of failure of cephalic vein cutdown. In consecutive patients who underwent pacemaker or ICD implants, a modified cephalic vein guidewire technique was performed. This technique was attempted in 289 pacemaker implants and 26 ICD implants (155 men, 160 women; mean age 74 +/- 10 years). The success rate for implantation of a single chamber and a dual chamber device by using this technique alone was 84% (54/64) and 74% (185/251), respectively (P = 0.10). In an additional 7% of patients with dual chamber implant, the cephalic vein can be used for passage of the ventricular lead. A cephalic venogram was required in 82 patients and facilitated the passage of the guidewire in 62 (79%) of them. No complication related to vascular access was observed with this technique. This technique failed in 54 (17%) of 315 patients due to (1) failure of cephalic vein isolation (48%), (2) venous stenosis (24%), or (3) venous torturosity or anomalies (28%). There were no significant differences in the patient's age, sex, type of device, and the fluoroscopic time for lead placement between patients with or without successful lead placement using this technique (all P > 0.05). In conclusion, a simple modification of the cephalic vein guidewire technique together with venography has facilitated the placement of leads during pacemaker and ICD implant. This technique is safe and applicable in the majority of patients and avoids the risk of subclavian puncture.

Is automatic mode switching effective for atrial arrhythmias occurring at different rates? A study of the efficacy of automatic mode and rate switching to simulated atrial arrhythmias by chest wall stimulation.

Automatic mode switching (AMS) is a useful means to avoid rapid ventricular response during atrial fibrillation (AF), but AMS cannot occur if the detected atrial rate during AF is below the mode switching criteria. This may be the result of antiarrhythmic medications, or when the atrial events fall within the atrial blanking period, or if the atrial amplitudes during AF are too small to be sensed. We hypothesize that the addition of an automatic rate switching (ARS) algorithm may complement AMS response during AF with different detected atrial rates. We studied the Marathon DDDR pacemaker (Model 294-09, Intermedics Inc.) with the AMS and ARS algorithms that are independently programmable but can also operate in combination. AF sensed above the AMS rate (160 beats/min) will lead to VDIR pacing, whereas AF below AMS rate will be tracked at an interim rate as dictate by the ARS, at a ventricular response that is 20 beats/min above the sensor indicated rate. Atrial tachyarrhythmias were simulated by chest wall stimulation (CWS). CWS was applied to 33 patients (16 men, 17 women, mean age 69 +/- 11 years) with a Marathon DDDR pacemaker using an external pacer to simulate AF occurring at two rate levels: above the AMS rate (programmed at 160 beats/min) at 180 beats/min and below the AMS rate at 120 beats/min. The maximum, minimum, and mean ventricular rates during CWS in DDDR mode with AMS alone, ARS alone, and their combination were compared. During CWS at 120 beats/min, the AMS plus ARS setting showed a mean ventricular rate of 79 +/- 3 beats/min and 124 +/- 14 beats/min in the AMS setting alone (P < 0.01). With CWS at 180 beats/min, the mean ventricular rate in the AMS plus ARS setting compared to the AMS setting alone was not significantly different. However, the variation in ventricular pacing rate was 7 +/- 14 beats/min in the AMS plus ARS setting and 40 +/- 42 beats/min in the AMS setting (P < 0.05). In conclusion, AMS is effective for simulated atrial tachyarrhythmias sensed above the AMS rate. Combined AMS with ARS is useful to handle simulated atrial tachyarrhythmia at a slower rate and to avoid rate fluctuation during AMS. There is also a possibility that this can be applied to the naturally occurring atrial tachyarrhythmias.

Computer model for glucose-limited growth of a single cell of Escherichia coli B/r-A. Reprinted from Biotechnology and Bioengineering, Vol. 26, Issue 3, Pp 203-216 (1984).

A computer model is described which is capable of predicting changes in cell composition, cell size, cell shape, and the timing of chromosome synthesis in response to changes in external glucose limitation. The model is constructed primarily from information on unrestricted growth in glucose minimal medium. The ability of the model to make reasonable quantitative predictions under glucose-limitation is a test of the plausibility of the basic biochemical mechanisms included in the model. Such a model should be of use in differentiating among competing hypotheses for biological mechanisms and in suggesting as yet unobserved phenomena. The last two points are illustrated with the testing of a mechanism for the control of the initiation of DNA synthesis and predictions on cell-width variations during the division cycle.

Developments in sensor-driven pacing.

This article reviews the recent major developments in the field of rate adaptive pacing. Including, the improved instrumentation of existing sensors, the use of multiple sensors to enhance sensor specificity or sensitivity, and the automation of sensor calibration. The physiologic benefits and programming of rate adaptive pacing are reviewed.

Efficacy and tolerability of continuous overdrive atrial pacing in atrial fibrillation.

Overdrive right atrial pacing has been used to prevent atrial fibrillation, but its efficacy in atrial fibrillation prevention and the patient tolerability and quality of life during high rate pacing remain uncertain. The objective of this study was to test the effects of a consistent atrial pacing algorithm that automatically paced the atrium at 30 ms shorter than the sinus P-P interval for atrial fibrillation prevention. Fifteen patients with sick sinus syndrome implanted with a Thera DR (model 7940 or 7960, Medtronic Inc.) were randomly programmed to rate adaptive dual chamber pacing (DDDR) or DDDR + consistent atrial pacing mode, each for an 8-week study period. The efficacy of consistent atrial pacing was assessed by the number of automatic mode switching and the number of premature atrial complexes. Symptoms and quality of life were assessed by the SF-36 quality of life questionnaire and an atrial fibrillation symptom checklist. The percentage of atrial pacing increased from 57 +/- 32% to 86 +/- 28%. Overall, there was no significant difference in the number of automatic mode switching episodes between DDDR and DDDR + consistent atrial pacing (47 +/- 90 vs 42 +/- 87, P > 0.05), but a significant reduction in premature atrial complexes by 74.7% (P < 0.001). There was no undue increase in atrial rate by the DDDR + consistent atrial pacing mode versus DDDR (63 +/- 13 vs 70 +/- 7 bpm). There was no significant difference in quality of life scores and symptom severity on frequency between the two modes of pacing, but a trend towards a lower frequency of symptoms in the DDDR + consistent atrial pacing mode compared with baseline (29.5 +/- 10.2 vs 25.1 +/- 9.7, P = 0.07). An algorithm that provides consistent atrial overdrive pacing can suppress atrial fibrillation triggering premature atrial complexes without the need to increase the overall atrial rate compared with conventional pacing. The algorithm appears to be well-tolerated, but further studies are needed to address the clinical impact of this atrial fibrillation prevention algorithm.

A comparative study on the behavior of three different automatic mode switching dual chamber pacemakers to intracardiac recordings of clinical atrial fibrillation.

Automatic mode switching (AMS) allows patients with dual chamber pacemakers who develop paroxysmal AF to have a controlled ventricular rate. The aim of this study was to (1) compare the rate-controlled behavior of three AMS algorithms in response to AF, in terms of speed and stability of response and resynchronization to sinus rhythm, and (2) compare the influence of pacemaker programming on optimal mode switching. We studied 17 patients (12 men, 5 women; mean age 59 +/- 15 years) who developed AF during electrophysiological study. Unfiltered bipolar atrial electrograms during sinus rhythm and AF were recorded onto high fidelity tapes and replayed into the atrial port of three dual chamber pacemakers with different mode switching algorithms (Thera, Marathon, Meta). The Thera pacemaker uses rate smoothing, and mode switches occur when mean sensed atrial rate exceeds the predefined AMS rate (MR). Marathon mode switches after a programmable number of consecutive rapid atrial events (NR). Meta DDDR monitors the atrial rate by a counter for atrial cycles faster than the programmed AMS rate. It increases or decreases the counter if the atrial cycle length is shorter or longer than the programmed AMS interval, respectively. Mode switch occurs when the AF detection criteria are met (CR). A total of 260 rhythms were studied. NR was significantly faster than MR and CR (latency 2.5 +/- 3 s vs 26 +/- 7 s vs 15 +/- 22 s, respectively, P < 0.0001). During sustained AF, MR resulted in the most stable and regular ventricular rhythm compared to NR or CR. In CR, ventricular rate oscillated between AMS and atrial tracking (cycle length variations: 44 +/- 2 s vs 346 +/- 109 s vs 672 +/- 84 s, P < 0.05). At resumption of sinus rhythm, MR resynchronized after 143 +/- 22 s versus 3.4 +/- 0.7 s for NR and 5.9 +/- 1.1 s for CR, resulting in long periods of AV dissociation when a VVI/VVIR mode is used after AMS. Programming of atrial refractory periods did not affect AMS response, although the speed of AMS onset can be adjusted by programming of onset criteria in the Meta DDDR. AMS algorithms differ in their ability to handle recorded clinical atrial arrhythmias. The rapid-responding algorithm exhibits rate instability, whereas slow responding algorithm shows a long delay in response and risk of AV dissociation. Thus different instrumentation of AMS may have clinical implications in patients with dual chamber pacemakers who develop AF.

Initial clinical experience with a new self-retaining left ventricular lead for permanent left ventricular pacing.

This study evaluated the performance of a new lead for permanent left ventricular (LV) pacing via the coronary sinus (CS) in four men and nine women (mean age = 71 +/- 13 years) with sick sinus syndrome. It consists of a 75-cm-long, 4.8-Fr, unipolar ventricular lead with a distal portion preshaped in an S curve to provide steerability and stability within the CS. Its efficacy and stability for permanent LV pacing were tested at implant, predischarge, and at 1, 3 and 6 months of follow-up. The lead was successfully implanted in 11/13 patients (85%) within a mean fluoroscopy time of 35 +/- 22 minutes. The final positions of the electrodes at the tip of the lead within venous tributaries of the CS were: (1) anterior (n = 2, 18%); (2) posterolateral (n = 5, 45%); and (3) the lateral (n = 4, 36%). Unsuccessful implants were due to unstable lead position (n = 1), or high pacing threshold (n = 1). There was no postprocedural lead dislodgment or significant changes in the R wave amplitude, LV pacing threshold and lead impedance up to 6 months of follow-up. In summary, this initial experience suggests that this new lead offers safe and reliable permanent LV pacing via the CS in the majority of patients and may be used in isolation or in conjunction with right ventricular pacing for biventricular synchronization.

Automatic optimization of resting and exercise atrioventricular interval using a peak endocardial acceleration sensor: validation with Doppler echocardiography and direct cardiac output measurements.

Peak endocardial acceleration (PEA) measured by an implantable acceleration sensor inside the tip of a pacing lead reflects ventricular filling and myocardial contractility. The contribution of the plateau phase of PEA as an indicator of optimal ventricular filling, hence of the appropriate atrioventricular interval (AVI) at rest and during exercise, was studied in 12 patients (age 69 +/- 6 years) with complete AV block and a PEA sensing DDDR pacemakers (Living 1 Plus, Sorin Biomedica). At a mean resting heart rate of 79 +/- 15 beats/min, the mean AVI optimized by PEA versus Doppler echocardiography (echo) were identical (142 +/- 37 vs 146 +/- 26 ms, P = 0.59). During submaximal exercise at a mean heart rate of 134 +/- 6 beats/min, AVI optimized by PEA was 135 +/- 37 ms. Cardiac output at rest, measured by the CO2 rebreathing method, was comparable with AVI determined by echo versus PEA (4.3 +/- 2.9 and 3.7 +/- 2.4 L/min, respectively), and increased to the same extent (8.0 +/- 3.9 vs 8.3 +/- 5.2 L/min) during submaximal exercise. In patients with AV block, AVI automatically set by PEA was comparable with AVI manually optimized by Doppler echocardiography and was associated with comparable exercise induced hemodynamic changes.

Reactivity of dioxoruthenium(VI) porphyrins toward amines. Synthesis and characterization of bis(arylamine)ruthenium(II), bis(arylamido)- and bis(diphenylamido)ruthenium(IV), and oxo(tert-butylimido)ruthenium(VI) porphyrins.

Reactions of dioxoruthenium(VI) porphyrins, [Ru(VI)O2(Por)], with p-chloroaniline, trimethylamine, tert-butylamine, p-nitroaniline, and diphenylamine afforded bis(amine)ruthenium(II) porphyrins, [Ru(II)(Por)(L)2] (L-p-ClC6H4NH2, Me3N, Por=TTP, 4-Cl-TPP; L=tBuNH2, Por = TPP, 3,4,5-MeO-TPP, TTP, 4-Cl-TPP, 3,5-Cl-TPP) and bis(amido)ruthenium(IV) porphyrins, [Ru(IV)(Por)(X)2] (X=p-NO2C6H4NH, Por=TTP, 4-Cl-TPP; X = Ph2N, Por = 3,4,5-MeO-TPP, 3,5-Cl-TPP), respectively. Oxidative deprotonation of [Ru(II)(Por)(NH2-p-C6H4Cl)2] in chloroform by air generated bis(arylamido)ruthenium(IV) porphyrins, [RuIV(Por)(NH-p-C6H4Cl)2] (Por=TTP. 4-Cl-TPP). Oxidation of [RuII(Por)-(NH2tBu)2] by bromine in dichloromethane in the presence of tert-butylamine and traces of water produced oxo(imido)ruthenium(VI) porphyrins, [RuVI-O(Por)(NtBu)] (Por=TPP, 3,4,5-MeO-TPP, TTP, 4-Cl-TPP, 3,5-Cl-TPP). These new classes of ruthenium complexes were characterized by 1H NMR, IR, and UV/visible spectroscopy, mass spectrometry, and elemental analysis. The structure of [Ru(IV)(TTP)(NH-p-C6H4Cl)2 . CH2Cl2 was determined by X-ray crystallography. The Ru-N bond length and the Ru-N-C angle of the Ru-NHAr moiety are 1.956(7) A and 135.8(6) degrees, respectively.

Experience with a single-pass, dual-electrode implantable atrial defibrillator lead for maintaining sinus rhythm in patients with recurrent atrial fibrillation.

The implantable atrial defibrillator is a new potential nonpharmacologic treatment for recurrent atrial fibrillation. The results of this study suggest that a simplified lead configuration, with a single-pass, dual-electrode atrial defibrillation lead can be used for both atrial fibrillation detection and defibrillation with an implantable atrial defibrillator.