Treating electrical storm : sympathetic blockade versus advanced cardiac life support-guided therapy.

BACKGROUND: Electrical storm (ES), defined as recurrent multiple ventricular fibrillation (VF) episodes, often occurs in patients with recent myocardial infarction. Because treating ES according to the Advanced Cardiac Life Support (ACLS) guidelines yields a poor outcome, we evaluated the efficacy of sympathetic blockade in treating ES patients and compared their outcome with that of patients treated according to the ACLS guidelines. METHODS AND RESULTS: Forty-nine patients (36 men, 13 women, mean age 57+/-10 years) who had ES associated with a recent myocardial infarction were separated into 2 groups. Patients in group 1 (n=27) received sympathetic blockade treatment: 6 left stellate ganglionic blockade, 7 esmolol, and 14 propranolol. Patients in group 2 (n=22) received antiarrhythmic medication as recommended by the ACLS guidelines. Patient characteristics were similar in the 2 groups. The 1-week mortality rate was higher in group 2: 18 (82%) of the 22 patients died, all of refractory VF; 6 (22%) of the 27 group 1 patients died, 3 of refractory VF (P<0.0001). Patients who survived the initial ES event did well over the 1-year follow-up period: Overall survival in group 1 was 67%, compared with 5% in group 2 (P<0.0001). CONCLUSIONS: Sympathetic blockade is superior to the antiarrhythmic therapy recommended by the ACLS guidelines in treating ES patients. Our study emphasizes the role of increased sympathetic activity in the genesis of ES. Sympathetic blockade-not class 1 antiarrhythmic drugs-should be the treatment of choice for ES.

Nonfluoroscopic three-dimensional mapping for arrhythmia ablation: tool or toy?

INTRODUCTION: Conventional mapping and ablation rely on fluoroscopy, which can result in imprecise positioning of the ablation catheter and long fluoroscopic exposure times. We evaluated a nonfluoroscopic three-dimensional mapping system, termed CARTO, and compared the results of ablation using this technique with those of conventional mapping. METHODS AND RESULTS: We compared the results of 88 arrhythmia ablations (79 patients) using CARTO with 100 ablations (94 patients) using the conventional technique. The ablations were separated into four groups: (1) AV nodal reentrant tachycardia (AVNRT); (2) atrial tachycardia/flutter; (3) ventricular tachycardia (VT); and (4) bypass tract tachycardia. We compared the success rate, complications, and fluoroscopy and procedure times. The ablation outcomes were excellent and comparable in all four types of the arrhythmias between the two techniques. Major complications included one cardiac tamponade in each group and one second-degree AV block in the conventional group. Fluoroscopy time was shorter using the CARTO technique: 10+/-7 versus 27+/-15 minutes for AVNRT (P < 0.01), 18+/-17 versus 44+/-23 minutes for atrial tachycardia and flutter (P < 0.01), 15+/-12 versus 34+/-31 minutes for VT (P < 0.05), and 21+/-14 versus 53+/-32 minutes for bypass tract tachycardia (P < 0.01). Procedure times were similar except for the bypass tract patients, which was shorter in the CARTO group, 4+/-1.3 versus 5.5+/-2.5 hours (P < 0.01). CONCLUSION: The electroanatomic three-dimensional mapping technique reduced fluoroscopy time and resulted in excellent outcome without increasing the procedure time.

Long-term antithrombotic treatment for atrial fibrillation.

Nonvalvular atrial fibrillation (AF) is the most common cardiac disorder causing stroke and systemic emboli. Recent clinical trials have clearly demonstrated the effects of antithrombotic treatment in preventing these devastating complications of AF. This review summarizes the salient findings of the first 5 published studies the Atrial Fibrillation, Aspirin, Anticoagulation Study (AFASAK) from Copenhagen, Denmark; the Boston Area Anticoagulation Trial for Atrial Fibrillation (BATAFF); the Canadian Atrial Fibrillation Anticoagulation study (CAFA); the Stroke Prevention in Non-rheumatic Atrial Fibrillation (SPINAF) study; and the Stroke Prevention in Atrial Fibrillation study (SPAF I) from the United States. These trials emphasize the unequivocal benefits of warfarin therapy compared with no treatment. SPAF II showed that aspirin is quite effective in younger patients (<75 years) who have no risk factors. The European Atrial Fibrillation Trial (EAFT) and SPAF III demonstrated that in older patients (>75 years) who had associated risk factors, warfarin therapy at the target international normalized ratio (INR) of 2-3, is the best treatment; however, a combination of low intensity fixed-dose warfarin and aspirin is ineffective. Thus, the guidelines recommended by the American College of Chest Physicians should be followed in treating patients with AF.

A nonfluoroscopic catheter-based mapping technique to ablate focal ventricular tachycardia.

The recent introduction of a nonfluoroscopic electroanatomical cardiac mapping system (CARTO) is an exciting development in catheter ablation treatment of cardiac arrhythmias. The system uses ultralow magnetic fields to locate a sensor positioned near the tip of a regular mapping and ablation catheter. The catheter location and electrograms are recorded and reconstructed in real-time and presented as a three-dimensional geometrical mapped color coded with the electrophysiological information. The CARTO represents an important tool to guide the ablation of patients who have focal tachycardia (e.g., right ventricular outflow tract [RVOT] tachycardia and idiopathic left ventricular [ILV] tachycardia). This study describes how the CARTO system is useful in mapping and ablating these arrhythmias. Two case illustrations, one patient with RVOT tachycardia and another with ILV tachycardia, are described in this article. The tachycardia was mapped and ablated using the new electromagnetic catheter technology creating an electroanatomical map of the arrhythmia focus for each tachycardia without fluoroscopy; both tachycardias were successfully ablated, terminated, and rendered noninducible. The CARTO system is useful in mapping and guiding the ablation of focal tachycardia and merits further study.

Assessment of coronary artery aneurysms with multiplane transesophageal echocardiography.

Coronary artery aneurysms are rare and may be difficult to detect clinically. Multiplane transesophageal echocardiography provides numerous imaging planes that may improve the assessment of coronary aneurysms and act as an adjunct to standard angiography. Five patients with angiographically detected coronary aneurysms were studied with multiplane transesophageal echocardiography and Doppler flow imaging. Transesophageal echocardiography was successful in identifying the size and characteristics of the coronary aneurysms. Doppler ultrasound identified markedly increased flow velocity in a patient with a coronary arteriovenous fistula and decreased coronary flow velocity in two patients with aneurysmal coronary arteries and intracoronary thrombus. Multiplane transesophageal echocardiography is a useful, noninvasive method of assessing coronary artery aneurysms and may act as an adjunct to angiography in identifying fistula anastomosis.

Problems in managing patients with long QT syndrome and implantable cardioverter defibrillators: a report of two cases.

Implantable cardioverter-defibrillators (ICDs) have been a successful adjunct to the management of arrhythmias in patients with Long QT syndrome (LQTS). In two patients, interactions between LQTS and the ICD were diagnosed and corrected. Oversensing of T waves was confirmed in the first, while in the second, the arrhythmia disappeared when T wave abnormalities improved after cessation of H2 blocker therapy. In patients with LQTS and an ICD, T wave oversensing should be considered. Interventions that may have an adverse effect on repolarization should be avoided.

Identification, distribution, and developmental changes of a melatonin binding site in the song control system of the zebra finch.

In many avian species, singing is a circadian or seasonal behavior that appears to be widely dependent on gonadal steroid hormones. To explore the possibility of a further hormone-dependent vocal control mechanism driven by the action of melatonin, we examined the binding of iodinated melatonin (IMEL) in the vocal control network of adult and juvenile (22- and 40-day-old) zebra finches. IMEL binding areas of the zebra finch brain were localized and characterized by using quantitative in vitro autoradiography. In the vocal control system, dense IMEL binding sites were restricted to the nucleus hyperstriatalis ventrale, pars caudalis (HVC). The binding of IMEL to the HVC and to visual areas, e.g., the ectostriatum and the optic tectum, was saturable and showed a single class of high-affinity binding sites with binding affinities (Kds) in the range of 5-20 pM. Competition experiments with various indols and IMEL showed that the IMEL binding site in the zebra finch brain has properties similar to the high-affinity melatonin receptor described in the chicken, in the house sparrow, and in the mammalian brain and retina. Similar to the zebra finch HVC, the HVC of other songbirds, e.g., male canaries and male house sparrows, has the most intense IMEL binding of all areas of the vocal control network. The IMEL binding in the forebrain vocal control areas of the zebra finch, but not that in the visual processing areas, was sexually dimorphic in correlation with the sexually dimorphic neuroanatomy of the forebrain vocal control areas. In the HVC, there is a developmental increase in the maximal number of binding sites for IMEL and in the protein content, so that the adult phenotype of dense IMEL binding develops between day 40 and day 80. The distribution and developmental pattern of IMEL binding in the song system suggests that melatonin has a role in the motor control of singing. Melatonin binding sites in HVC could link HVC-based song control to circadian and circannual changes in the photoperiod independent of gonadal steroids.

Adrenergic control of rat pineal NO synthase.

We have previously shown that exposure of rats to constant light (LL) induced a decrease in NO synthase (NOS) activity in the pineal gland. We present here the evidence that chronic (5 days) norepinephrine (NE) or isoproterenol treatment prevents the effect of LL and enhances pineal NOS activity in LL animals. This effect of NE appears to be mediated by beta-adrenoceptors, because it was not mimicked by the alpha-agonist phenylephrine. Pineal NOS activity was reduced in 16-h light/8-h dark animals treated for 4 days with the beta-adrenergic antagonist propranolol but not with the alpha 1-antagonist prazosin, indicating again an involvement of beta-adrenergic receptor in the control of NOS. Treatment with adrenergic antagonists did not affect cortical NOS activity, suggesting that the control of NOS is different in these two tissues or that the pineal expresses a specific isoform of the enzyme. Taken together, these data suggest that NE controls NOS in the pineal gland through beta-adrenergic receptors. To our knowledge, this represent the first demonstration of a regulation of NOS by a neurotransmitter in the CNS, as assayed under Vmax conditions.

Effect of photoperiod on the pineal melatonin rhythm in neonatal rats.

Photoperiod already modulates pineal melatonin rhythm in neonatal rats. Pineal melatonin content was about 500 fmol during day and increased up to 2000 and 3000 fmol at night in 8- and 12-day-old rats, respectively. On long photoperiods (LD 14:10) melatonin was increased above 1000 fmol for about 8 h while on short photoperiods (LD 8:16) for 12 to 14 h. Melatonin pattern may thus transduce photoperiodic effects in neonatal rats. However, no differences in plasma LH were found in the rats kept on long and short photoperiods.

Chemical modifications of melatonin receptors in chicken brain.

The membrane-bound or solubilized melatonin receptors were treated with protein-modifying agents under specific conditions and then assayed for 125I-melatonin binding in order to obtain information on amino acids present in the ligand binding domain. The reagents specific for sulfhydryl (N-ethylmaleimide and p-chloromercuribenzoate), guanidyl (phenylglyoxal), and amino groups (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and 1-fluoro-2,4-dinitrobenzene) inhibited 125I-melatonin binding in a dose-dependent manner, and their effects were prevented by pretreatment with cold melatonin. These results suggest the presence of cysteine, arginine, and lysine residues in the melatonin binding domain. Decreased sensitivity of 125I-melatonin binding to guanine nucleotides after N-ethylmaleimide pretreatment suggests the presence of another sulfhydryl group within the coupling domain between the receptor and G protein. Tyrosine reagents tetranitromethane, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, N-acetylimidazole, and p-nitrobenzenesulfonyl fluoride also inhibited 125I-melatonin binding, and their effects were prevented by cold melatonin pretreatment; however, they were effective only at concentrations when cross-reaction with a sulfhydryl group may occur. Histidine reagent diethyl pyrocarbonate inhibited 125I-melatonin binding in a dose-dependent manner, and its action was reversed by cold melatonin. However, diethyl pyrocarbonate had a smaller effect in a solubilized receptor preparation and, therefore, it could have modified a site remote from the ligand binding site. Our data do not suggest the presence of tryptophanyl, aspartic, or glutamic residues at the ligand binding domain.

Ontogenesis of melatonin receptors in anterior pituitary and pars tuberalis of golden hamsters.

The ontogenesis of melatonin receptors in the anterior pituitary and pars tuberalis of the Golden hamster was studied using [125I]iodomelatonin as a ligand. The affinity of the binding site to the ligand (Kd) was in the range 21 to 54 pM and it did not change significantly during development. The concentration of the [125I]iodomelatonin binding sites in the anterior pituitary was highest in one-day-old hamsters (Bmax = 14 fmol/mg protein) and thereafter gradually decreased. In adults it reached to about 6% of the neonatal values. In contrast, the concentration of the binding sites in pars tuberalis did not change significantly during ontogenesis and it was in the range of 3 to 5 fmol/mg protein.

Daily changes in melatonin binding sites and the effect of castration.

The effect of castration and/or neonatal administration of testosterone propionate (TP) on 125I-melatonin binding and its daily changes was studied in rat anterior pituitary (AP) and in pars tuberalis/median eminence (PT/ME). In animals kept on a light/dark cycle of 12:12 h there was a marked increase in binding site density (Bmax) in the evening as compared to the morning, while there were no differences in the affinity (Kd). On a light/dark cycle of 8:16 h the daily rhythm in Bmax was abolished and the values were intermediate. Neonatal TP administration which increases the sensitivity of the reproductive axis to melatonin and photoperiodic regulations had no effect on the binding parameters in AP and in PT/ME. Castration, however, increased binding site density in AP by 85% while it had no effect on the affinity of the binding site (Kd).

Effects of menthol on peripheral nerve and cortical unit responses to thermal stimulation of the oral cavity in the rat.

Neurophysiological responses were recorded in individual fibers of the lingual and chorda tympani nerves and in single cortical neurons in the rat in response to a battery of tactile, thermal and chemical stimuli applied to the oral cavity. Two categories of thermally sensitive units were identified. Chorda tympani fibers and one type of cortical unit ('Type I') were activated by cold water stimulation but were unaffected by warm water or menthol. In contrast, lingual fibers and a different category of cortical units ('Type II') were extremely sensitive to menthol exposure. These units were cold water sensitive, however, this sensitivity was suppressed following menthol presentation.

Cortical unit responses to chemical stimulation of the oral cavity in the rat.

The gustatory sensitivity of individual cortical neurons in the rat was examined using a wide range of chemical stimuli. Several subsets of cortical taste cells were identified based on similarities in their response profiles. Although adjacent cortical neurons can differ in their responsiveness to individual tastants, some overlap in taste sensitivities is usually observed.

Comparison of glucose and glucose plus lipid as caloric sources in parenterally fed rats.

This study investigated the etiology of fat infiltration of the liver during total parenteral nutrition. We measured the content of liver lipids, serum lipids, liver lipogenic enzymes, rates of in vivo fatty acid synthesis, and carcass composition in rats during continuous intravenous (iv) and intragastric (ig) feeding of two diets containing either 100% glucose or 75% glucose-25% lipid (20% Intralipid). Two groups of orally (O) fed rats were given solid diets similar to either the glucose or glucose-lipid solution in energy and nitrogen content. All six groups of rats (285-295 g) received 230 kcal X kg-1 X day -1 and 766 mg N X kg-1 X day-1. Total liver fat was greater after feeding the glucose diet ig rather than iv. However, feeding the glucose-lipid diet ig but not iv reduced the accumulation of liver fat by 49%. There were no differences in serum glucose concentrations among the three groups fed the glucose solution. Serum glucose concentrations in iv and O rats fed either diet were not significantly different; whereas feeding the glucose-lipid solution ig lowered serum glucose compared with the 100% glucose solution. Insulin concentrations were similar among all groups. The concentrations of serum triglycerides and cholesterol were higher in the groups fed the glucose-lipid diet. The activities of the liver lipogenic enzymes and rates of fatty acid synthesis were higher in iv- and ig-fed rats receiving the glucose diet compared with the glucose-lipid diet.(ABSTRACT TRUNCATED AT 250 WORDS)

[The Penrose drain as a finger tourniquet: a study]. / Der Penrose-Drain als Fingertourniquet: Eine Untersuchung.

As finger tourniquets are used frequently in surgery of the hand, it is necessary to study the safety of this technique in order to prevent complications of ischemia such as described by Dove and Clifford in 1982. Finger tourniquets applied with high pressure compromise the blood flow to the finger as well as damage the digital nerves. The authors use their previously described technique for controlling the pressure beneath a penrose drain and measure the tissue pressure generated by such a technique by placing a Wick catheter along the neurovascular bundle of a cadaver finger as well as in the soft tissue of an in vivo Sprague Dowley rat hindlimb preparation. The pressures measured by this technique were consistent with what one would expect based on the estimated pressure generated by placing marks spaced 26 mm apart and stretching them the circumference of an average sized adult finger.

Gustatory cortex in the rat. I. Physiological properties and cytoarchitecture.

The precise cytoarchitectural localization of taste-elicited cortical responses in the rat was studied using a combination of anatomical and physiological techniques. Multi-unit responses to tongue tactile, thermal and gustatory stimuli were recorded along 97 electrode penetrations positioned parallel to the lateral convexity of the brain and marking lesions were placed at the sites of transitions in these functional properties. Lesions made at sites that received different sensory inputs were consistently located within different cytoarchitectural subdivisions. In this manner, taste cortex in the rat was localized to the agranular insular cytoarchitectural region, in contrast to its traditional assignation to granular insular cortex. Instead, tongue temperature was found to be represented in the cortical area previously termed gustatory, i.e., in ventral granular cortex where layer IV attenuates.

Gustatory cortex in the rat. II. Thalamocortical projections.

The thalamic relay for lingual tactile, thermal, and gustatory sensibility was defined electrophysiologically in the rat. Subsequently, injections of tritiated leucine were centered in these functionally defined locations in separate series of rats. Following suitable survival periods, the brains were processed for autoradiographic tracing of axonal projections. After injections confined to the thalamic gustatory relay, labeled fibers terminated in agranular insular cortex. These results provide support for our previous experiments correlating neurophysiological localization of rat gustatory cortex and regional cytoarchitecture, and contrast with the traditional assignation of gustatory cortex to the granular insular area.

Ergot alkaloids inhibit 3H-naloxone binding to opiate receptors in the rat striatum and hippocampus.

The authors tested direct effect of selected ergot alkaloids (lisuride, terguride, DH-ergotoxine, DH-ergotamine and DH-ergocristine) on specific 3H-naloxone binding in the rat striatum and hippocampus. In the striatum they found that DH-ergotoxine (a substance with high affinity for noradrenergic receptors) inhibited specific 3H-naloxone binding much more strongly than lisuride and terguride (substances with a greater affinity for dopaminergic and serotoninergic receptors). DH-ergotoxine, which inhibited binding significantly more in the striatum than in the hippocampus, displayed the greatest activity. The results show differences in the degree of inhibition by the various groups of ergot alkaloids in the striatum. In the case of DH-ergotoxine there was also a difference in the degree of inhibition in the striatum and the hippocampus.