Urinary Excretion Profile of Torasemide and its Diuretic Action in Dogs

The plasma concentration profile, urinary excretion rate and diuretic response were studied in anaesthetized dogs after an intravenous administration of torasemide or furosemide. The urinary excretion rate of furosemide decreased rapidly after administration. The plasma concentration, which is related to the urinary excretion profile, also decreased rapidly. The diuretic response, which reflected the excretion rate, occurred rapidly after administration but lasted for a short time. The urinary excretion rate of torasemide was much lower than that of furosemide and decreased slowly after administration. The plasma concentration also decreased slowly. The diuretic response to torasemide occurred more slowly but lasted longer than the response to furosemide. These results suggest that the diuretic response profile of either diuretic depends on their urinary excretion rate, and that the difference in the diuretic response between torasemide and furosemide may be explained by the different transfer rate of the drugs from the plasma to the nephron.     

Atrial Fibrillation Therapy in Patients with a CRT Defibrillator with Wireless Telemetry

Background: Atrial fibrillation (AF) is a major cause of morbidity and mortality, especially in patients with congestive heart failure.
Objectives: The purposes of this international, prospective multicenter study were to evaluate the efficacy of atrial shock therapy in patients with a cardiac resynchronization therapy defibrillator (CRT-D) and to evaluate the safety of the new CRT-D. The effectiveness of a new wireless telemetry system was also evaluated.
Methods: A total of 282 patients, without permanent AF, who had indications for a CRT-D were included. Atrial shock therapy was tested on both spontaneous and induced AF episodes. The effectiveness of the Medtronic wireless telemetry system (Conexus; Medtronic Inc., Minneapolis, MN, USA) was also tested. Secondary endpoints included the heart failure Clinical Composite Response, system performance evaluation, and adverse event summary.
Results: Atrial shock therapy was successful in 168 of 171 episodes (98.2%). Of these, 138 episodes were induced and 33 were spontaneous. Successful cardioversion occurred in 137 of the 138 induced-AF episodes (86.1% with 12 joule (J), 13.1% with 24 J, and 0.7% with 35 J). During the first 3 months of implant, there were 43 system-related complications in 37 subjects out of 278 subjects. There were 1,999 Conexus telemetry uses recorded during this study. This includes 282 uses during the implant procedure. There were no cases of complete loss of telemetry or any adverse events reported using this system.
Conclusion: We achieved an atrial shock efficacy of 98.2% in patients who met standard CRT-D indications. The wireless telemetry performed well with no reported unanticipated adverse device effects.     

Coronary Venous Lead Implantation after an Evaluation by Virtual Histology Intravascular Ultrasound and Stenting of a Stenosis

We describe a patient who developed coronary vein (CV) stenosis shortly (<3 months) after an initial left ventricular (LV) lead implantation with significant fibrous tissue. The virtual histological intravascular ultrasound analysis was useful for characterizing the plaque component of the stenotic lesion and formulating the strategy. A summarized review of the CV angioplasty for LV lead implantations disclosed that CV stenosis was often found in patients who had a previous history of cardiac surgery or an LV lead implantation and that a stent implantation was required to deploy the LV lead in the targeted CV in some (9.3%) patients. (PACE 2013; 36:e59–e63)     

The Disposition of Thioperamide,a Histamine H3-Receptor Antagonist,in Rats

Abstract— An HPLC method using an ovomucoid-conjugated column has been developed for measurement of thioperamide, a histamine H₃ antagonist, with a minimum quantitation limit of 0·05 μg mL^?1 The assay was used to study the disposition of thioperamide in rats. After bolus intravenous administration of thioperamide (10 mg kg^?1), the plasma concentration decreased monoexponentially with a half-life of 26·9 min. The apparent total body clearance of thioperamide from rat plasma was 74·6 mL min^?1 kg^?1. Although thioperamide was quickly transferred to various tissues, its concentrations in peripheral tissues were higher than that in the brain. However, the brain regional tissue/plasma ratios of thioperamide increased continuously after its injection.     

Significance of monitoring plasma levels of amitriptyline, and its hydroxylated and desmethylated metabolites in prediction of the clinical outcome of depressive state

Abstract The clinical significance of monitoring the plasma levels of amitriptyline and its metabolites in prediction of the clinical outcome of depressive episode was investigated in 49 inpatients. Discriminant analysis of drug concentrations (at two weeks after initiation of drug treatment) and clinical outcome revealed that increasing the plasma levels of amitriptyline, cis-isomers of hydroxylated metabolites (Z-10-hydroxyamitriptyline and Z-10-hydroxynortriptyline) predicted a better clinical outcome, while increasing of plasma levels of nortriptyline and trans-isomers of hydroxylated metabolites (E-10-hydroxyamitriptyline and E-10-hydroxynortriptyline) were shown to predict a poor clinical outcome in the depressive episode of the subjects, and that clinical outcome of approximately 73% of the subjects could be correctly predicted.     

Catheter Ablation of Ventricular Tachycardia in Patients with Right Ventricular Dysplasia: Identification of Target Sites by Entrainment Mapping Techniques

Objective: To identify target sites for radiofrequency ablation of ventricular tachycardia (VT) by entrainment mapping techniques in patients with arrhythmogenic right ventricular dysplasia. Methods: Entrainment mapping and radiofrequency ablation of eight VTs was performed in seven patients. Radiofrequency ablation was applied at 31 reentry circuits sites that were classified based on findings during entrainment. Results: By entrainment criteria the 31 sites were classified as: exit sites (n = 12), proximal sites (n = 6), and outer loop sites (n = 13). Radiofrequency current application terminated VT at 7 of 31 sites: 2 of 12 exit sites (17%), 4 of 6 proximal sites (67%), and 1 of 13 outer loop sites (8%). Conclusion: Radiofrequency ablation terminated VTs most often at sites proximal to the exit as opposed to outer loop sites and exit sites (P = 0.05). The critical isthmus for ablation of VT in right ventricular dysplasia often may be distant to the exit.     

Catheter Ablation for Ventricular Tachycardia from a Diverticulum at the Right Ventricular Outflow Tract

A case is presented of a 73-year-old man with drug resistant ventricular tachycardia that originated from the right ventricular outflow tract. A right ventriculogram showed a diverticulum in the interventricular septum at the right ventricular outflow tract. Low energy radiofrequency catheter ablation within the diverticulum was performed successfully and safely.     

ATP‐Induced Dormant Pulmonary Veins Originating from the Carina Region After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

Dormant Pulmonary Veins from the Carina Region . Introduction: Elimination of transient pulmonary vein recurrences (dormant PVs) induced by an ATP injection and ablation at the PV carina region is an effective strategy for atrial fibrillation (AF) ablation. The relationship between dormant PVs and the PV carina region has not been evaluated. Methods: A total of 212 consecutive symptomatic AF patients underwent circumferential PV electrical isolation (CPVEI) with a double lasso technique. They were divided into 2 groups in a retrospective review; Group 1: those given an ATP injection during an intravenous isoproterenol infusion after the CPVEI (n = 106), and Group 2: those in which it was not given after the CPVEI (n = 106). Radiofrequency energy was applied at the earliest dormant PV activation site identified using a Lasso catheter on the CPVEI line and then PV carina region if it was ineffective. Results: After a successful PVEI, 54 patients (51%) in Group 1 had PV reconnections during an ATP injection. Acute PVEI sites were observed on the carina region within the CPVEI line in the right PVs (16%) and left PVs (10%). Dormant PVs were reisolated at the carina region in the right PVs (23%) and left PVs (26%). The distribution of the dormant PV sites, except for the RIPV, significantly differed from that of the acute PVEI sites (P < 0.05). Further, AF recurred significantly in the Group 2 patients as compared to those in Group 1 during 16 ± 6.1 months of follow‐up (P < 0.05). Conclusion: PV carina region origins may partly be responsible for an acute PVEI and potential recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 494‐500, May 2010)     

Edrophonium-Induced Right Ventricular Outflow Tract Tachycardia

Idiopathic right ventricular outflow tract-ventricular tachycardia (RVOT-VT) generally occurs when sympathetic nervous system activity is increased, though, in a few patients, it develops when parasympathetic nervous activity (PNA) is increased. Among 101 consecutive patients with RVOT-VT confirmed by endocardial catheter mapping, 5 (4.9%) presented with nocturnal RVOT-VT. Autonomic nervous balance was studied by heart rate variability (HRV) analysis from 24-hour ambulatory electrocardiogram (ECG). Standard programmed ventricular stimulation (PVS), ventricular burst pacing, and drug provocation were performed to induce RVOT-VT. In the studied five patients, the average number of mostly nocturnal ventricular premature contractions (VPCs) was 6649 ± 4472/day. Two patients had nocturnal nonsustained RVOT-VT on 24-hour ambulatory ECG recordings. The HRV analysis revealed that a progressive increase in high-frequency power coincided with an increase in VPCs or development of RVOT-VT at night, whereas low/high frequency ratio did not change significantly during the 24-hour period. RVOT-VT could not be induced by PVS, ventricular burst pacing, or isoproterenol or adenosine triphosphate i.v. However, RVOT-VT could only be induced by edrophonium, 5 mg i.v., in all patients. An increase in PNA was observed in a few patients before the development of RVOT-VT. Edrophonium facilitated induction of RVOT-VT in such patients.     

Tachycardia Associated with Twin Atrioventricular Nodes in an Infant with Heterotaxy and Interruption of Inferior Vena Cava

We report a 12‐month‐old boy with heterotaxy and interruption of inferior vena cava who showed sustained tachycardia associated with twin atrioventricular nodes (AVNs). Atrioventricular reciprocating tachycardia with antegrade conduction through the posterior AVN and retrograde conduction through the anterior AVN were successfully ablated using an upper approach from the left internal jugular vein. (PACE 2012; 35:e302–e305)