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1.
Verapamil, a calcium channel-blocking drug, was administered IV at a dosage that ranged from 0.05 to 0.15 mg/kg of body weight to 14 dogs with supraventricular tachycardia. The dosage was titrated, administering 0.05 mg/kg every 5 to 30 minutes following the initial 0.05 mg/kg dose in all but 1 dog. The drug terminated the arrhythmia in 12 dogs and slowed the ventricular rate in 1 dog. One dog was unresponsive to verapamil administration and became transiently hypotensive after the administration of a total dose of 0.15 mg/kg over 5 to 6 minutes. Various arrhythmias occurred after verapamil administration, but none required additional treatment or caused serious sequelae. Verapamil was an effective treatment for acutely converting supraventricular tachycardia to sinus rhythm in these dogs. It appears to be safe when administered in the aforementioned dosage range.  相似文献   

2.
A five-year-old, female-spayed boxer was referred for frequent and medically refractory paroxysmal supraventricular tachycardia. Diagnostic evaluation found no underlying structural heart or systemic diseases. Three-dimensional electroanatomical mapping and radiofrequency ablation were pursued. Activation mapping of normal sinus rhythm demonstrated the location of the sinus node in the posterolateral region of the right atrium. Activation mapping of the tachyarrhythmia identified a centrifugal activation pattern originating from the right atrium at the posterolateral aspect of the tricuspid valve orifice, suggestive of focal atrial tachycardia. A total of 10 ablation lesions were delivered to the earliest activation site. The dog recovered without complications and no recurrence of supraventricular tachycardia was noted on subsequent follow-ups.  相似文献   

3.
Atrial fibrillation and its treatment in a five year old purebred Holstein cow was explored with electrocardiography. Conversion of atrial fibrillation to a normal sinus rhythm was accomplished with the oral administration of a cumulated total of 125 gm of quinidine sulfate over a period of five days.  相似文献   

4.
The objective of this study was to evaluate the electrocardiographic alterations in the cardiac rhythm in dogs treated with levamisole hydrochloride over a period of 24 hours. Thirty-six mixed-breed dogs, both male and female, all clinically healthy, were used in the experiment. The dogs were divided into 6 groups with 6 dogs in each group, according to dosage and route of administration. The Holter test was initiated immediately after the treatment, and was maintained for 24 hours. In the group treated with 10 mg/kg by way of subcutaneous injection, one of them showed ventricular premature complexes, sometimes isolated and other times in pairs, and ventricular tachycardia, concentrated mainly in the first hour after administration of the drug. In the group of 6 animals treated subcutaneously with 25mg/kg, four showed isolated ventricular premature complexes, ventricular bigeminy and trigeminy, mainly during the first 2 hours after administration of the drug. All the animals in the other groups showed sinus arrhythmia followed by sinus arrest. The disturbances in the cardiac rhythm observed in clinically healthy animals treated with levamisole hydrochloride, indicate that it is preferable to avoid subcutaneous administration of levamisole hydrochloride and that the oral administration of the drug should be done with caution.  相似文献   

5.
BACKGROUND: Lidocaine is most frequently used to treat ventricular arrhythmias. However, lidocaine may have an antiarrhythmic effect for certain supraventricular arrhythmias. HYPOTHESIS: We hypothesized that lidocaine would be effective in converting experimentally induced atrial fibrillation (AF) to sinus rhythm and that a decrease in the dominant frequency (DF) and an increase in the organization as judged by the spectral entropy (SE) would occur over the course of the conversion. ANIMALS: Seven German Shepherd (GS) Dogs. METHODS: Dogs were anesthetized with fentanyl and pentobarbital. AF was induced with standard pacing protocols while left and right atrial monophasic action potentials (MAP) were recorded. The power spectra from the MAP recordings were analyzed to determine DF and SE during treatment with boluses of 2 mg/kg lidocaine. RESULTS: Lidocaine converted AF to sinus rhythm in all dogs and all episodes (n = 19). Conversion time was 27-87 seconds. After atropine, sustained AF was not induced; however, 5 episodes of atrial tachycardia resulted, and 3 were converted with lidocaine. Frequency domain analysis of 12 conversion sequences showed that left and right DF of the MAP signals decreased from the time of injection to conversion to sinus rhythm (P < .001). Mean SE indicated a gradient between the left and right atria (P = .003) that did not change during conversion. CONCLUSIONS AND CLINICAL IMPORTANCE: Vagally associated AF in GS dogs is terminated with lidocaine. Lidocaine is likely an effective treatment in clinical dogs with vagally associated AF.  相似文献   

6.
This is areport of a 10-year-old female neutered Doberman Pinscher with a clinical diagnosis of myelopathy. The dog was anesthetized using oxymorphone, thiopental, and halothane in oxygen for a cerebrospinal tap and a myelogram. Iohexsal injection into the subarachnoid space by lumbar puncture was uneventful. Additional iohexal was given into the cerebellomjedullary cistern. Immediately following iohexal administration into the cerebellomedullary cistern, several electrocardiographic changes occurred. Two extended periods of asystole responded to intravenous glycopyrrolate administration. A slow multiform ventricular escape rhythm was established after the second dose of glycopyrrolate. Ultimately, atrial activity with apparent A V dissociation resumed, atrial fibrillation developed, and the rhythm converted to normal sinus rhythm. The dog had a normal cardiac examination the following day. Two days later, the dog was anesthetized using a similar anesthetic regimen with maintance on isoflurane in oxygen for a hemilaminectomy. The dog recovered uneventfully from surgery and was discharged 2 days later.  相似文献   

7.
Three cattle with gastrointestinal disease were given neostigmine as part of the treatment for postsurgical ileus. All 3 cattle developed atrial fibrillation either before or during neostigmine administration, and 2 converted to normal sinus rhythm after cessation of treatment.  相似文献   

8.
A 12-year-old spayed female German shorthaired pointer dog sustained extensive bite wounds around the neck. At presentation, atrial fibrillation was identified with a rapid ventricular response rate of 300 beats per minute (bpm). The ventricular response rate rapidly decreased to 130 bpm following administration of hydromorphone and oxygen. Based on the rate, antiarrhythmic therapy was not initiated. The heart rhythm converted back to sinus rhythm by the time of the first recheck evaluation 2 days later, and the dog remained in sinus rhythm at all subsequent evaluations. With the resolution of the arrhythmia, paroxysmal atrial fibrillation was suspected. The underlying etiology of the arrhythmia was not determined; however, imbalances in autonomic tone associated with trauma and/or direct trauma to the heart were hypothesized.Key clinical message:This report indicates a possible role of imbalances in autonomic tone due to trauma in the development of paroxysmal atrial fibrillation and suggests that it should be a differential diagnostic consideration in patients with atrial fibrillation following trauma. Primary treatment of atrial fibrillation may not be needed in these cases if the ventricular response rate is not rapid, or if there is spontaneous conversion to sinus rhythm.  相似文献   

9.
Of 16 dogs treated medically and surgically for gastric dilatation-volvulus, 11 developed electrocardiographic evidence of ventricular dysrhythmias. Seven of these dogs had ventricular dysrhythmias for the first time during their hospitalization after surgery. The ventricular dysrhythmias included ventricular premature depolarizations, slow ventricular rhythms, paroxysmal ventricular tachycardia, ventricular tachycardia, and multifocal ventricular tachycardia. Two of these dogs had electrocardiographic evidence of atrial premature depolarizations at the time of hospitalization. Treatment with lidocaine hydrochloride or procainamide hydrochloride was successful in reestablishing sinus rhythm in 9 of the 11 dogs with ventricular dysrhythmias.  相似文献   

10.
A 1-year-old male Boxer dog presented with sustained supraventricular tachycardia and tachycardia-induced cardiomyopathy. Conversion to sinus rhythm was achieved initially with intravenous lignocaine and subsequently with oral procainamide. Oral procainamide treatment was relatively successful in maintaining normal sinus rhythm with no side effects apart from a reversible change in coat colour. Electrophysiological studies demonstrated the presence of an accessory pathway connecting the right atrium to the right ventricle and confirmed the diagnosis of orthodromic atrioventricular reciprocating tachycardia. Radiofrequency catheter ablation of the accessory pathway led to permanent resolution of the supraventricular tachycardia and for 9.5 years the dog has had no further signs of cardiac disease. The successful treatment of this condition highlights the importance of differentiating tachycardia-induced cardiomyopathy from dilated cardiomyopathy.  相似文献   

11.
Foetal electrocardiograms (ECG) were obtained from 39 of 50 Thoroughbred foaling mares close to delivery. The 50 newborn foals were studied electrocardiographically during their adaptive period, immediately after birth. In 48 foals there were paroxysmal arrhythmias or mixed arrhythmias. The most common arrhythmias were sinus arrhythmias including wandering pacemaker (32/50) and atrial premature contraction (30/50). The others observed were atrial fibrillation (15/50), ventricular premature contraction (10/50), partial atrioventricular block (7/50), ventricular tachycardia (4/50), atrial tachycardia (3/50) and idioventricular rhythm (1/50). The duration of the arrhythmias was approximately 5 min, and in all cases the arrhythmia disappeared within 15 min of birth. From foetal ECG recordings, no indication of the likelihood of neonatal arrhythmias was detected. With the exception of 2 cases, all foals have continued to grow and develop normally. These arrhythmias are considered normal physiological processes in newborn Thoroughbred foals during the adaptive period to extra-uterine life. High vagal tone and hypoxaemia at birth are probably the main contributing factors.  相似文献   

12.
BACKGROUND: Although atrial arrhythmias are clinically important in horses, atrial electrophysiology has been incompletely studied. HYPOTHESES: Standard electrophysiologic methods can be used to study drug effects in horses. Specifically, the effects of diltiazem on atrioventricular (AV) nodal conduction are rate-dependent and allow control of ventricular response rate during rapid atrial pacing in horses undergoing quinidine treatment. ANIMALS: Fourteen healthy horses. METHODS: Arterial blood pressure, surface electrocardiogram, and right atrial electrogram were recorded during sinus rhythm and during programmed electrical stimulation at baseline, after administration of quinidine gluconate (10 mg/kg IV over 30 minutes, n = 7; and 12 mg/kg IV over 5 minutes followed by 5 mg/kg/h constant rate infusion for the remaining duration of the study, n = 7), and after coadministration of diltiazem (0.125 mg/kg IV over 2 minutes repeated every 12 minutes to effect). RESULTS: Quinidine significantly prolonged the atrial effective refractory period, shortened the functional refractory period (FRP) of the AV node, and increased the ventricular response rate during atrial pacing. Diltiazem increased the FRP, controlled ventricular rate in a rate-dependent manner, caused dose-dependent suppression of the sinoatrial node and produced a significant, but well tolerated decrease in blood pressure. Effective doses of diltiazem ranged from 0.125 to 1.125 mg/kg. CONCLUSIONS AND CLINICAL IMPORTANCE: Standard electrophysiologic techniques allow characterization of drug effects in standing horses. Diltiazem is effective for ventricular rate control in this pacing model of supraventricular tachycardia. The use of diltiazem for rate control in horses with atrial fibrillation merits further investigation.  相似文献   

13.
A Standardbred gelding was anesthetized on three occasions over a 3 year period. Anesthesia was induced with xylazine and thiamylal on the first occasion, with xylazine, guaifenesin, and thiamylal on the second, and with acepromazine, guaifenesin, and ketamine on the third. Anesthesia was maintained with halothane during each episode. The horse had atrial fibrillation (AF) after induction of anesthesia on the first two occasions. Because arterial blood pressure remained within normal limits during AF and anesthesia, conversion to normal sinus rhythm with quinidine was not attempted. Reversion to normal sinus rhythm occurred within 12 hours of recovery after each of the first two anesthetic episodes. The gelding remained in normal sinus rhythm throughout the third anesthetic period and recovered uneventfully. Potential causes for AF in anesthetized horses are discussed.  相似文献   

14.
To determine a safe and efficacious dose of flecainide acetate for treating equine atrial fibrillation (Af), the safe dosage level was determined by injecting 1, 2, or 3 mg/kg i.v. of 1% flecainide acetate solution at a rate of 0.2 mg/kg/min to five clinically healthy horses. Clinical signs and the ECG were monitored (HR, PR, QRS, and QT intervals) and blood was taken to measure the plasma flecainide concentration pre- and post-administration. No abnormal signs were observed in the 1- or 2-mg/kg groups, while agitation was observed in three of five horses in the 3-mg/kg group. The QRS, and QT intervals for the 3-mg/kg group increased significantly. The peak plasma flecainide concentrations were 1.316 +/- 358 (SD) ng/ml, 1,904 +/- 314 ng/ml, and 2,251 +/- 387 ng/ml for the 1-, 2-, and 3-mg/kg groups, respectively. To evaluate the efficacy of flecainide, Af was induced by right atrial pacing in six clinically healthy horses, and 1% flecainide acetate solution was then administered until they converted to sinus rhythm. All horses with induced Af converted. For the conversion, a total dose of 1.40 +/- 0.63 mg/kg flecainide was required, the duration of administration was 7.00 +/- 3.15 min and plasma flecainide concentration at conversion was 1,303 +/- 566 ng/ml. In conclusion, flecainide acetate is a safe and effective antiarrhythmic agent for equine Af, and the clinically effective dosage is 1 to 2 mg/kg.  相似文献   

15.
OBJECTIVE: To evaluate cardiac electrical function in the Spectacled Flying Fox (bat) infested with Ixodes holocyclus. DESIGN: Prospective clinical investigation of bats treated for naturally occurring tick toxicity. PROCEDURE: ECGs were performed on bats with tick toxicity (n = 33), bats that recovered slowly (n = 5) and normally (n = 5) following treatment for tick toxicity, and on normal bats with no history of tick toxicity (n = 9). RESULTS: Bats with tick toxicity had significantly prolonged corrected QT intervals, bradycardia and rhythm disturbances which included sinus bradydysrhythmia, atrial standstill, ventricular premature complexes, and idioventricular bradydysrhythmia. CONCLUSIONS: The QT prolongation observed on ECG traces of bats with tick toxicity reflected delayed ventricular repolarisation and predisposed to polymorphic ventricular tachycardia and sudden cardiac death in response to sympathetic stimulation. The inability to document ventricular tachycardia in bats shortly before death from tick toxicity may be explained by a lack of sympathetic responsiveness attributable to the unique parasympathetic innervation of the bat heart, or hypothermia-induced catecholamine receptor down-regulation. Bradycardia and rhythm disturbances may be attributable to hypothermia.  相似文献   

16.
Atrial fibrillation (AF) is one of the most important arrhythmias of dogs. In a previous study, we determined the dosage of intravenously administered diltiazem necessary to reduce ventricular response (VR), cardiac output (CO), and mean systemic arterial pressure (P(Ao)) to values similar to those observed during sinus rhythm (SR) before induction of AF. The present study was conducted to establish an acute, effective dosage of diltiazem given PO. AF was produced by rapid atrial pacing in healthy, anesthetized Beagle Hounds. Dogs were instrumented to record hemodynamic and electrophysiological parameters. Four dogs were given 2.5 mg/kg diltiazem, and another 4 dogs were given 5 mg/kg diltiazem by stomach tube, whereas 4 other dogs received vehicle in equivalent volumes. Plasma concentrations of diltiazem were measured at various intervals after dosing. A dosage of 5 mg/kg diltiazem produced plasma concentrations of 32-100 ng/mL 3 hours after administration, concentrations within the published effective range for dogs with naturally occurring AF. Between 2 and 3 hours after this dosage, the rate pressure product (RPP) and an index of left ventricular efficiency returned to values similar to those observed during SR. Thus, we believe that diltiazem at anorally administered dosages of 5 mg/kg should be considered to produce therapeutic blood concentrations and favorable hemodynamic effects in dogs with naturally occurring AF. These data must be extrapolated with caution to dogs with long-standing AF produced by natural causes.  相似文献   

17.
Electrocardiographic tracings of an English Bulldog referred for cardiogenic shock due to an orthodromic atrioventricular reciprocating tachycardia conducted with intraventricular conduction disturbance and mimicking ventricular tachycardia (VT) are presented. At admission the surface ECG showed a wide QRS complex tachycardia (WCT) that was converted to sinus rhythm using manual cardioversion (chest thump). This change revealed pre-existing right bundle branch block, and a final diagnosis of supraventricular tachycardia (SVT) with intraventricular conduction disturbance was made. Electrophysiologic study defined the SVT mechanism as an atrioventricular macroreentrant tachycardia mediated by a single mid-septal accessory pathway. The differentiation between various types of WCT is essential when antiarrhythmic therapy is considered. The surface ECG should be systematically evaluated in order to recognize the characteristic features of SVT and VT. Moreover chest thump procedure can be very helpful in the attempt to convert the rhythm to sinus rhythm and to correctly recognize the underlying arrhythmia.  相似文献   

18.
Intravenous administration of quinidine gluconate converted atrial fibrillation (AF) to sinus rhythm in 9 of 12 horses. Twelve horses that were diagnosed by ECG to have AF were administered up to 11 mg of quinidine gluconate/kg of body weight in 1.0- to 1.5-mg/kg bolus injections every 10 to 15 minutes. The total dose of quinidine administered IV ranged from 1.8 to 5.8 g. Increased ventricular rate, apprehension, and mild depression were observed during treatment. Other signs of toxicosis were not observed. One horse was successfully treated with IV administered quinidine gluconate on 3 occasions. Intravenous administration of quinidine is a safe and effective alternative for treatment of AF in some horses.  相似文献   

19.
An asymptomatic nine-year-old Dobermann Pinscher underwent a screening for dilated cardiomyopathy. Echocardiography revealed left ventricular eccentric hypertrophy and systolic dysfunction; the rest of the echocardiographic parameters were within normal limits. Holter monitoring demonstrated sinus rhythm as the dominant cardiac rhythm during the first hours of the recording. Then, during a period of physiologically enhanced vagal tone (sleep), spontaneous development of atrial flutter (AFL) associated with variable ventricular response was documented. Alternation between AFL and paroxysmal atrial fibrillation was also observed. Subsequently, during a period of physiological increase of sympathetic tone (physical activity/excitement), spontaneous conversion of AFL to sinus rhythm occurred. In light of these findings, a presumptive diagnosis of vagal AFL was made. The images here described allow us to study the onset, behavior and termination of this intriguing electrocardiographic entity.  相似文献   

20.
Quinidine is effective for treatment of atrial fibrillation (AF) in horses, but often accelerates ventricular response rate. Diltiazem effectively controls heart rate response to AF in other species. This investigation determined the effects of diltiazem on cardiac rate and rhythm, left ventricular (LV) function, central hemodynamics, and peripheral blood flow in normal, standing, nonsedated horses. A dose-finding study was performed. Afterward, 8 healthy horses were treated with diltiazem IV every 30 minutes to achieve cumulative dosages of 0 (saline control), 1, 1.5, and 2 mg/kg. Plasma diltiazem concentration, heart rate and rhythm (by electrocardiography), LV function and central hemodynamics (by cardiac catheterization), LV dimensions (by echocardiography), and forelimb blood flow (by Doppler sonography) were determined during each treatment period. Diltiazem plasma concentrations between 390 and 910 ng/mL were achieved, with considerable variation among horses. Cardiac effects of diltiazem included intermittent depression of the sinus and atrioventricular (AV) nodes and mild impairment of systolic and diastolic LV function. Vascular effects of diltiazem included arterial vasodilatation, increased limb blood flow, and decreased systemic vascular resistance. Baroreceptor reflex-mediated sympathetic activation increased sinus node rate and presumably blunted the depressive effects of diltiazem on myocardial and nodal tissues. Two horses developed transient high-grade sinus arrest with severe systemic hypotension. Diltiazem appears relatively safe in healthy horses, but dosage may be limited by hypotension from vasodilatation and direct suppression of sinus node discharge. Because of its inhibitory effects on AV nodal conduction, diltiazem may prove useful for heart rate control in horses with AF.  相似文献   

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