Infestation in the dog by the paralysis tick, Ixodes holocyclus — 4. Cardiovascular effects
| Autor: | Goodman Ah, D. M. Turner, Jan E. Ilkiw |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Bradycardia
medicine.medical_specialty Sinus tachycardia Sinus bradycardia Blood Pressure Ventricular tachycardia Electrocardiography Dogs Heart Rate Internal medicine Heart rate medicine Animals Dog Diseases cardiovascular diseases General Veterinary biology business.industry Arrhythmias Cardiac General Medicine Tick Toxicoses biology.organism_classification medicine.disease Myocardial Contraction Tick Paralysis Ixodes holocyclus Autonomic nervous system medicine.anatomical_structure Anesthesia Vascular resistance Cardiology Vascular Resistance medicine.symptom business |
| Zdroj: | Australian Veterinary Journal. 65:232-235 |
| ISSN: | 1751-0813 0005-0423 |
| DOI: | 10.1111/j.1751-0813.1988.tb14306.x |
| Popis: | SUMMARY: To determine the extent and signficance of changes in heart rate and rhythm noticed previously in dogs paralysed with Ixodes holocyclus, two studies were undertaken. In one the electrocardiogram was recorded at stages throughout the disease and the traces analysed for changes, while in the second a detailed study of the effect of Ixodes holocyclus on the cardiovascular system was undertaken. The electrocardiographic changes were extremely variable between stages and between dogs. Generally, if a dysrhythmia occurred in stages 1, 2 or 3 it tended to be sinus tachycardia, ventricular tachycardia or sinus arrest. In stage 4 sinus arrest, sinus bradycardia, or sinus or ventricular tachycardia were the prominent dysrhythmias, whereas in stage 5 sinus bradycardia predominated. Cardiovascular measurements indicated an increase in peripheral vascular resistance leading to a significant elevation in mean arterial pressure at all stages of the disease. Cardiac output was decreased significantly only at stage 2, although it was below the control measurements at all stages. Pulmonary arterial pressure was significantly elevated at stages 2, 3 and 4 due most probably to an increase in pulmonary vascular resistance. Myocardial contractility was not significantly changed throughout the disease. The changes observed in the electrocardiogram and the cardiovascular system in stages 1, 2 and 3 are unlikely to be due to hypoxia and could represent dysfunction of the autonomic nervous system. During stages 4 and 5 oxygen levels were below normal and the bradycardia seen terminally is almost certainly due to hypoxaemia. However the cardiovascular changes are more definite than those reported in hypoxia and while they may be partly hypoxic-induced, it seems likely that other factors, such as alterations in sympathetic and parasympathetic nervous system activity, may play a role. |
| Databáze: | OpenAIRE |
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