Dehydrobenzperidol and disopyramide in A-V conduction

The effects on A-V conduction of dehydrobenzperidol (Droperidol) 0.35 and 1.0 mg/kg i.v.) and disopyramide (1, 5 and 10 mg/kg i.v.) were tested in anesthetized, open chest and paced dogs. His's bundle electrograms were recorded by means of a catheter electrode or by a sutured electrode-bearing plaque in the A-V nodal region. Droperidol at the lower dose did not modify conduction time, while 1.0 mg/kg (3 times the usual clinical dose), prolonged atrial-His conduction without modifying H-V interval. Disopyramide 1 mg/kg caused a non-significant decrease in atrial-His concuction time, while in doses of 5 and 10 mg/kg it prolonged both conduction times (S-H and H-V), due to a predominant direct depressant effect, which is opposite to the atropinic actions of the drug.     

Amygdala-prefrontal interactions and conditioned bradycardia in the rabbit

Damage to the amygdala or medial prefrontal cortex (mPFC) produces deficits in learned autonomic adjustments. Whether connections between these 2 structures are necessary for acquiring classically conditioned heart rate (HR) decelerations was studied. Connections between them were interrupted by unilateral lesions of the mPFC and amygdala, but on opposite sides of the brain. One experiment focused on the mPFC and amygdala central nucleus and a second on the mPFC and amygdala basolateral complex. Bilateral lesions of either structure disrupted the HR conditioned response. The response of the 2 crossed lesioned groups also was smaller than that of the sham-operated and unilateral lesioned groups, but significant conditioned stimulus-evoked bradycardia occurred in both, suggesting that although interactions between the amygdala and mPFC may normally occur during associative emotional responding, these connections are not necessary for the acquisition of conditioned bradycardia.     

Relative bradycardia and lymphopenia in patients with babesiosis

The medical records of 17 patients with babesiosis were reviewed. Nine of 17 patients (52.9%) presented with fever (temperature, > 101 degrees F), and 8 of the 9 patients (88.9%) had relative bradycardia. Four of the nine patients (44.4%) had morning temperature spikes during initial hospitalization. As revealed by laboratory analysis, 13 of 17 patients (76.5%) with babesiosis had lymphopenia, and 5 of 17 patients (29.4%) had rouleaux formation in their peripheral blood smears. These newly described clinical and laboratory findings represent additional clinical and laboratory features that may be used as diagnostic clues in the differential diagnosis of babesiosis.     

Asymptomatic arrhythmias in patients with symptomatic paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia

BACKGROUND: Paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia are recognized clinically when patients seek treatment for symptoms due to recurrent arrhythmias; atrial fibrillation also increases the risk of stroke. The frequency with which asymptomatic arrhythmias occur in patients with these arrhythmias is unknown. METHODS AND RESULTS: Twenty-two patients with paroxysmal atrial fibrillation (n = 8) or paroxysmal supraventricular tachycardia (n = 14) were studied for 29 days with two different ambulatory ECG-monitoring techniques to measure the relative frequency of asymptomatic and symptomatic arrhythmias. All class I antiarrhythmic drugs, calcium channel blockers, beta-blockers, and digitalis were withheld. Sustained asymptomatic arrhythmia events (defined as lasting at least 30 seconds) were documented using continuous ambulatory ECG monitoring once weekly for a total of 5 of the 29 study days; symptomatic arrhythmia events were documented using transtelephonic ECG monitoring for all 29 days of the study. In the group of patients with paroxysmal atrial fibrillation, asymptomatic arrhythmia events occurred significantly more frequently than symptomatic arrhythmia events; the mean rates, expressed as events/100 d/patient (95% confidence interval), were 62.5 (40.4, 87.3) and 5.2 (2.7, 9.0) (P < .01); the ratio of the mean rates was 12.1 (5.8, 26.4). In contrast, in the group of patients with paroxysmal supraventricular tachycardia, asymptomatic arrhythmia events were significantly less frequent than symptomatic arrhythmia events; the mean rates were 0.0 (0.0, 5.3) and 7.4 (5.0, 10.6) (P = .02). The ratio of the mean rates was 0.0 (0.0, 0.8). CONCLUSIONS: In a group of patients with paroxysmal atrial fibrillation, sustained asymptomatic atrial fibrillation occurs far more frequently than symptomatic atrial fibrillation. However, it is not known whether asymptomatic atrial fibrillation is a potential risk factor for stroke even when patients are not having symptomatic arrhythmias.     

Amygdala–prefrontal interactions and conditioned bradycardia in the rabbit.

Damage to the amygdala or medial prefrontal cortex (mPFC) produces deficits in learned autonomic adjustments. Whether connections between these 2 structures are necessary for acquiring classically conditioned heart rate (HR) decelerations was studied. Connections between them were interrupted by unilateral lesions of the mPFC and amygdala, but on opposite sides of the brain. One experiment focused on the mPFC and amygdala central nucleus and a second on the mPFC and amygdala basolateral complex. Bilateral lesions of either structure disrupted the HR conditioned response. The response of the 2 crossed lesioned groups also was smaller than that of the sham-operated and unilateral lesioned groups, but significant conditioned stimulus-evoked bradycardia occurred in both, suggesting that although interactions between the amygdala- and mPFC may normally occur during associative emotional responding, these connections are not necessary for the acquisition of conditioned bradycardia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pre-emptive glycopyrrolate 0.2 mg and bradycardia during gynaecological laparoscopy with mivacurium

In a prospective, randomized, double-blind, placebo-controlled trial, the effect of pre-emptive glycopyrrolate 0.2 mg given intravenously on the incidence of bradycardia in patients undergoing elective gynaecological laparoscopy with mivacurium neuromuscular blockade was investigated. Seven out of 32 (21.6%) control patients developed bradycardia (heart rate < 50 min-1), compared with 3 of 31 (9.6%) patients receiving glycopyrrolate (P = 0.4). Glycopyrrolate 0.2 mg, given immediately before induction in gynaecological laparoscopy with mivacurium, did not significantly reduce the incidence of intraoperative bradycardia.     

Effects of atropine and scopolamine on bradycardia and emetic symptoms in otoplasty

OBJECTIVE: To assess the effects of unilateral or bilateral otoplasty on bradycardia and postoperative nausea and vomiting (PONV) and the efficiency of transdermal scopolamine in the prophylaxis of PONV. Study Design: Post hoc assessment of the data from a double-blind, randomized study. METHODS: Fifty otoplasty patients were studied; half of them received randomly and in double-blind fashion a transdermal therapeutic system (patch) of scopolamine (TTS-scopolamine) as prophylaxis against PONV before general anesthesia. The placebo group received atropine 10 microg x kg(-1) intravenously during induction. RESULTS: The scopolamine-treated patients suffered more from moderate peroperative bradycardia (8/25; P < .05) than the atropine-treated patients (1/25). Two patients wearing a half of the TTS-scopolamine patch needed intravenous atropine. After unilateral otoplasty, none of the TTS-scopolamine-treated patients and 50% of the atropine-treated patients suffered from PONV. After bilateral operation, the respective incidences were 39% and 81% (P < .01). After unilateral otoplasty no patient needed droperidol, but after bilateral otoplasty, 12 of 19 of the atropine-treated and 4 of 18 (P < .05) of the scopolamine-treated patients needed droperidol. The mean numbers of doses of droperidol were 0.8+/-0.9 and 0.3+/-0.6 (P < .05), respectively. Two additional patients, wearing half of the TTS-scopolamine patch, suffered from mild central anticholinergic syndrome. CONCLUSION: TTS-scopolamine offers effective prophylaxis against PONV (auriculoemetic reflex), but does not protect from bradycardia (auriculocardiac reflex) in otoplasty. Cutting of the TTS-scopolamine patch may lead to undesirable side effects.     

Tachycardia, hypertension and syncope. A case report

A case of orthostatic syncope with tachycardia and hypertension is described. Initially the condition was interpreted as a dysfunction in the neurovascular orthostatic regulation, but extensive physiologic examinations failed to give a comprehensive explanation. A psychiatric examination demonstrated the condition eventually to be hysteriform and the patient was completely cured by psychotherapy.     

Orbital mass in a child causing somnolence, nausea and bradycardia

Aorto-esophageal fistula due to ruptured thoracic aortic aneurysm is very rare but is associated with extremely high mortality. An 81-year-old woman was admitted due to repeated hematemesis. Endoscopic examination revealed ulceration with blood clot on the mid-esophagus and compression of an extra-esophageal mass. The thoracic CT scan revealed an aorto-esophageal fistula due to a ruptured descending thoracic aortic aneurysm. Surgery was performed on April 3, 1996. We report an aorto-esophageal fistula managed successfully in one stage by resection and replacement of the aortic aneurysm with a prosthetic graft and total esophageal resection. The esophagus was reconstructed using orthotopic gastric interposition with omentopexy around the prosthetic aortic graft. The postoperative course was uneventful and there have been no signs of mediastinal sepsis, graft infection or pyothorax 12 months postoperatively. We suggest that the resection of both the aneurysm and the esophagus as well as the immediate reconstruction of the esophagus by orthotopic gastric interposition to obliterate the retrosternal space are important technique in the management of intrathoracic infections.     

Opioid modulation of attention-related responses: delta-receptors modulate habituation and conditioned bradycardia

A rehabilitation program toward restoring upper limb movements based on neuromuscular electrical stimulation (NMES) depends on closed-loop control performance, which has been limited by the development of sensors for practical daily use. This work proposes a system to obtain force feedback. The system is comprised of a Lycra commercial glove with force sensing resistors (FSR's) attached to the distal phalanxes of the thumb, index and long fingers. After amplification and filtering, the signal is digitized through an analog-to-digital (A/D) converter. The polynomial fitting coefficients for the characteristic curves, obtained during the sensor calibration process, were inserted in the software thus enabling the reading of forces exerted during object manipulation. The system was applied to 30 normal subjects in order to verify its feasibility and to acquire knowledge of the normal hand function. Different ways of grasping have been detected according to the Force versus Time curve pattern and to the fingers predominantly used in grasping. Results have also shown the influence of parameters such as gender, age, hand size, and object weight in the normal function. The system did show efficacy. It was able to determine grasp forces during object manipulation for up to 73% of the studied sample. This is significant since a single glove was used in a wide range of subjects. For best results in medical applications, the glove should be tailored to the particular characteristics of an individual user.     

Action of clonidine on the baroreceptor pathway and medullary sites mediating vagal bradycardia

In anaesthetized dogs, clonidine (10 mug/kg i.v.) increased the spontaneous firing of the carotid sinus nerve and decreased blood pressure and heart rate. After transection of the spinal cord, clonidine decreased heart rate and this bradycardia was abolished by selective baroreceptor denervation. Clonidine (1 mug/kg) injected into the vertebral artery of anaesthetized dogs, pretreated with a beta-adrenoceptor blocking agent (S 2395: 50 mug/kg i.v.) potentiated the bradycardia induced by stimulation of the carotid sinus nerve but did not change the hypotension and bradycardia produced by stimulation of the nucleus tractus solitarius or of the nucleus ambiguus. In anaesthetized cats with bilateral destruction of nuclei tractus solitarii, clonidine (10 mug/kg i.v.) decreased blood pressure and heart rate. Clonidine (2 mug/kg), injected into the vertebral artery of anaesthetized dogs pretreated with a beta-adrenergic blocking agent (S 2395: 50 mug/kg i.v.) or guanethidine, induced a bradycardia but the discharges of the carotid sinus nerve were not increased. Selective baroreceptor denervation abolished this bradycardia. In conclusion, these experiments provide direct evidence that the central facilitory effect of clonidine on baroreceptor impulses play a role in the bradycardic effect of the drug. This facilitation is likely localized in the nucleus tractus solitarius at the first synapse of baroreceptor fibres. The vagally mediated bradycardia can be explained by an increase in baroreceptor discharges and by the central facilitation of baroreceptor impulses. The site of the hypotensive effect of clonidine did not seem to be localized in the nucleus tractus solitarius.     

Apnoea and bradycardia during epileptic seizures: relation to sudden death in epilepsy

OBJECTIVE: To record non-invasively ictal cardiorespiratory variables. METHODS: Techniques employed in polysomnography were used in patients with epilepsy undergoing EEG-video recording at a telemetry unit. RESULTS: Apnoea (> 10, range > 10-63, mean 24 s) was seen in 20 of 47 clinical seizures (three secondary generalised, 16 complex partial, and one tonic) and 10 of 17 patients. Apnoea was central in 10 patients, but obstructive apnoea was also recorded in three of 10. Oxyhaemoglobin saturation (SpO2) dropped to less than 85% in 10 seizures (six patients). An increase in heart rate was common (91% of seizures). Bradycardia/sinus arrest was documented in four patients (mean maximum RR interval 5.36, range 2.8-8.6 s) but always in the context of a change in respiratory pattern. CONCLUSION: Ictal apnoea was often seen. The occurrence of bradycardia in association with apnoea suggests the involvement of cardiorespiratory reflexes. Similar mechanisms may operate in cases of sudden death in epilepsy.     

Cannabinoid-induced hypotension and bradycardia in rats mediated by CB1-like cannabinoid receptors

Previous studies indicate that the CB1 cannabinoid receptor antagonist, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1H-pyrazole-3-carboxamide HCl (SR141716A), inhibits the anandamide- and delta9-tetrahydrocannabinol- (THC) induced hypotension and bradycardia in anesthetized rats with a potency similar to that observed for SR141716A antagonism of THC-induced neurobehavioral effects. To further test the role of CB1 receptors in the cardiovascular effects of cannabinoids, we examined two additional criteria for receptor-specific interactions: the rank order of potency of agonists and stereoselectivity. A series of cannabinoid analogs including the enantiomeric pair (-)-11-OH-delta9-THC dimethylheptyl (+)-11-OH-delta9-THC dimethylheptyl were evaluated for their effects on arterial blood pressure and heart rate in urethane anesthetized rats. Six analogs elicited pronounced and long lasting hypotension and bradycardia that were blocked by 3 mg/kg of SR141716A. The rank order of potency was (-)-11-OH-delta9-THC dimethylheptyl > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > THC > anandamide > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol, which correlated well with CB1 receptor affinity or analgesic potency (r = 0.96-0.99). There was no hypotension or bradycardia after palmitoylethanolamine or (+)-11-OH-delta9-THC dimethylheptyl. An initial pressor response was also observed with THC and anandamide, which was not antagonized by SR141716A. We conclude that the similar rank orders of potency, stereoselectivity and sensitivity to blockade by SR141716A indicate the involvement of CB1-like receptors in the hypotensive and bradycardic actions of cannabinoids, whereas the mechanism of the pressor effect of THC and anandamide remains unclear.     

Effects of respiration and posture on paroxysmal supraventricular tachycardia

The capacity of deep inspiration and the dependent body position to terminate episodes of tachycardia was studied in 11 patients with recurrent paroxysmal supraventricular tachycardia (PSVT). In eight patients, a deep inspiration and a dependent position repeatedly terminated episodes of PSVT. Reasons for failure were found in the other three patients. A deep inspiration or assumption of a dependent position dramatically raised arterial blood pressure and terminated episodes of PSVT by reflexly increasing vagal drive. The magnitude of the rise in blood pressure was directly proportional to the depth of the inspired volume and to the extent of body dependency. The upright position attenuated the respiratory-induced increase in blood pressure and blocked PSVT termination. Likewise, vagal blockade with atropine did not affect the effects of respiration or dependent position on blood pressure but prevented termination of PSVT.