首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The cardiac conduction system (CCS) is crucial for regulating heartbeats; therefore, clinicians and comedicals involved in cardiovascular medicine treatment must have a thorough understanding of the CCS structure and function. However, anatomical education of the CCS based on actual dissection and observation is uncommon, although such educational methodology promotes three-dimensional structural understanding of the observed object. Based on previous studies, we examined the CCS structure in the heart of a swine (pig, Sus scrofa domestica) which has been used in the biological, medical and anatomical curricula as science teaching materials, by using macroscopic dissection procedures. Most CCS structures in a young pig heart were successfully identified and illustrated on a macroscopic scale. The atrioventricular bundle (His bundle) was located on the lower edge of the membranous interventricular septum and was clearly distinguished from the general myocardial fibres by its colour and fibre arrangement direction. Following the atrioventricular bundle towards the atrium or ventricle with properly removing the endocardium and myocardium, the atrioventricular node or the right and left bundles appeared respectively. In contrast, the sinoatrial node was not identified. The anatomy of the CCS in young pig hearts was essentially similar to that previously reported in humans and several domestic animals. Our findings of the CCS in young pig hearts are expected to be useful for medical and anatomical education for medical and comedical students, young clinicians and comedical workers.  相似文献   

2.
Verapamil hydrochloride, a calcium channel blocker, has been used in domestic animals. Its effects on electrical activities of the heart of donkeys were studied in this preliminary research work. This experiment was carried out on 10 healthy donkeys ranging in age from 4 to 7 years and mean body weight of 155 ± 18.6 kg. The electrocardiogram (ECG) was recorded on a base apex lead before (for 3 days), during, and after verapamil injection (10, 20, 30, 40, 50, and 60 minutes). Verapamil hydrochloride (0.3 mg/kg body weight) was given via catheterizaion as an intravenous bolus over 2 minutes. Heart rate, rhythm, ECG morphology, amplitude, durations, and intervals were measured and taken into consideration and values were compared. Results showed that heart rate was significantly increased at the time of injection from 55 ± 10.7 before injection to 77.61 ± 12.6 beats per minute after injection (P < .05). Duration of P and T waves; P-R interval, and also P-R segment were increased (P < .05). However, duration of QRS complex, P-P and R-R intervals, and S-T segment were significantly decreased after verapamil injection (P < .05). Sinus arrest (2 cases), bradycardia (1 case), and wandering pacemaker (1 case) were recorded before treatment and verapamil injection did not affect these arrhythmias, except in one case in which sinus arrest disappeared. However, after injection of verapamil, four types of arrhythmias (wandering pacemaker [WPM], sinus tachycardia, 1st degree AVB, and 2nd degree AVB) were recognized. These arrhythmias (with the exception of tachycardia) can be related to the increase of vagal tone activity that might be attributed to the negative effect of verapamil on SA and atrioventricular block [AV] nodes.  相似文献   

3.
The atrioventricular (AV) bundle and the moderator band in the canine heart were examined by scanning electron microscopy. The AV bundle and the moderator band both were comprised of large, cylindrically shaped cells. These cells were highly organized into bundles, with minimal lateral communication between bundles. There was extensive cell-to-cell communication between cells within a bundle. The end branching of individual cells was prominent, with some interbundle communication. These results are discussed in relationship to the electrophysiologic properties of the AV bundle and the conduction velocity.  相似文献   

4.
The electrical impulse for cardiac contraction is generated in the Sinoatrial node (SA node), subsequently spreads to the Atrioventricular node (AV node) and continues in the Atrioventricular bundle (AV bundle). The AV node may not always be present in different avian species and seems to differ in location and contents between species. In this study, the anatomy and histology of the AV node were studied five female adult ostriches (Struthio camelus). Routine paraffin sectioning and transmission electron microscopic method were performed. The study showed that in the ostrich, the AV node is located in the endocardium of the atrial surface of the right atrioventricular valve adjacent to the fibrous ring. The parenchyma of the AV node is formed by small specialized muscle fibres that are spread within a loose connective tissue network. The AV node is not covered by a connective tissue sheath and some arterioles are present. Nerve fibres are seen related to the node. Ultrastructurally, they stain lighter and contain fewer organized myofibrils than usual myocardial cells. The myofibril bundles run parallel to one another and have interspersed mitochondria, which display distinct cristae. The cells have a large euchromatic nucleus with a clear perinuclear area, and they connected by desmosomes. The ostrich is, thus, one of the birds that have the AV node, whose position varies from the other birds.  相似文献   

5.
Five racehorses in apparently normal condition succumbed to sudden cardiac death (SCD) during or shortly after intensive training exercise. Cardiopathologic examination was performed. In 1 of the 5 horses, the use of an electrocardiogram (ECG) recording taken continuously for 440 sec enabled us to analyze some of the arrhythmias in the terminal event of SCD. The ECG tracing exhibited the R-on-T phenomenon following a pair of ventricular premature contractions (VPCs). The phenomenon rapidly degenerated into ventricular fibrillation, which led to cardiac arrest. In all 5 horses cardiopathologic examination revealed the following lesions: (i) foci of myocardial fibrosis in the right atrium located close to the sinoatrial (SA) node, (ii) fibrotic and/or fibroplastic changes in the upper portion of the interventricular septum, including the atrioventricular (AV) conduction system, and (iii) arterio- and arteriolosclerosis of the SA and AV node vessels. Pathogenetically, the process by which the focal lesions of myocardial ischemia secondary to vascular sclerosis progressed into fibrosis and/or fibroplasia could play a major role in the genesis of arrhythmias. Presumably the fibrotic and/or fibroplastic changes in the area of the AV bundle and its bundle branches are closely related to the onset of fatal ventricular arrhythmias such as VPCs, deteriorating into ventricular fibrillation. SCD in training and racing Thoroughbred horses appears to be due to arrhythmia.  相似文献   

6.
Morphologic features of the canine atrioventricular (AV) node were evaluated, using histochemical cholinesterase reactions and scanning electron microscopy. Three distinct regions of the AV node were observed: the transitional zone, superficial AV node, and deep AV node. The transitional zone lacked distinct cellular arrangement, and the cells were large and round with extensive branching on the ends. Superficial AV nodal cells were elongated, tightly packed, and smaller than were transitional cells. The superficial AV node was the densest zone of the AV node. Cell-to-cell contact was end-to-end. Deep AV nodal cells were long, formed laminated fascicles, were larger than the superficial AV nodal cells, and were continuous with the AV bundle.  相似文献   

7.
The normal values are reported of the concentration of vitamin A (retinol) in the plasma of 44 male and female adult camels (Camelus dromedarius) in the United Arab Emirates. The concentrations of the vitamin in the plasma of eight camels of both sexes afflicted with aflatoxicosis were also determined. The mean concentration (±SD) of the vitamin in healthy camels was 460.1±49.3 ng/L. Sex had no significant effect on the concentration of the vitamin. Camels with aflatoxicosis had a mean concentration of retinol in the plasma of 243.4±32.3 ng/L. The concentrations of aflatoxins in the liver and ruminal contents of these animals were 18.2±1.3 and 243.4 g/kg, respectively.  相似文献   

8.
This report describes transient trifascicular block in three cats presented with lethargy and inappetence, and elevated cardiac troponin I concentrations.The electrocardiogram (ECG) of cat 1 showed a sinus rhythm with pronounced first-degree atrioventricular (AV) block, right bundle branch block, and left anterior fascicular block. The ECG of cat 2 showed truncular left bundle branch block alternating with left anterior fascicular block coupled with prolonged PR intervals, second-degree heart block, and paroxysmal third-degree AV block. The ECG of cat 3 showed first-degree AV block with concomitant right bundle branch block. The diagnosis of trifascicular block was made when paroxysmal third-degree AV block was documented.All cats recovered with medical management within weeks. Each cat resumed a sinus rhythm. Elevated cardiac troponin I concentrations suggested myocarditis that improved.  相似文献   

9.
The available information about anatomical characteristics of the cardiovascular system of the alpaca (Vicugna pacos, Linnaeus 1758) is scarce. The general objective of this work was to describe its heart anatomy. We dissected six adult animals and five neonates. The heart of the alpaca was located in the middle mediastinum, with a craniocaudal extension from the third to the sixth rib. No ligament that connected the fibrous pericardium to the sternum or to the diaphragm was detected. In the right atrium, there was a developed crista terminalis and small pectinate muscles. In the right ventricle, the septomarginal trabecula was very large. From the proximities of the interventricular septum arose small septomarginal trabeculae that ended in carnous trabeculae of the septal wall. The left atrium included little developed pectinate muscles. On the left ventricle, both papillary muscles were bilobed. Two left septomarginal trabeculas were detected in this ventricle. The left subclavian artery was originated from the aortic arch separately from the brachiocephalic trunk, and bicarotid trunk was present. The other branches of the subclavian artery were similar to the domestic ruminants. The arterial supply of the heart was of the right type. In conclusion, the heart anatomy of alpaca and the irrigation of thoracic cavity were more similar to those of old world camels and different from domestic ruminants.  相似文献   

10.
Third degree atrioventricular (AV) block was observed in a patient with a roughly spherical mass measuring approximately 1 × 1 × 1 cm, visible in the basilar portion of the interventricular septum on 2-dimensional transthoracic echocardiographic examination. The patient had a brief history of lethargy and episodic collapse, and the owner elected to euthanize the dog after the mass lesion was discovered. Necropsy revealed multiple masses within the interventricular septum, ventricular free walls and atrial myocardium. The final diagnosis was large cell (T-cell) lymphosarcoma.  相似文献   

11.
The pharmacokinetics of diphenhydramine (DPHM) was compared in camels (n = 8) and horses (n = 6) following intravenous (i.v.) administration of a dose of 0.625 mg/kg body weight. In addition, the metabolism and urinary detection time of DPHM was evaluated in camels. The data obtained (median and range in brackets) in camels and horses, respectively, were as follows. The terminal elimination half lives (h) were 1.58 (1.13–2.58) and 6.11 (4.80–14.1), and the total body clearances (L/h per kg) were 1.42 (1.13–1.74) and 0.79 (0.66–0.90). The volumes of distribution at steady state (L/kg) were 2.38 (1.58–4.43) and 5.98 (4.60–8.31) and the volumes of the central compartment of the two compartment pharmacokinetic model were 1.58 (0.80–2.54) and 2.48 (1.79–3.17). All the pharmacokinetic parameters in camels were significantly different from those of horses. Five metabolites of DPHM were tentatively identified in the camel's urine. Two metabolites, diphenylmethoxyacetic acid and 1-(4-hydroxyphenyl)-phenylmethoxyacetic acid, were present in the acid fraction. Two metabolites, desamino-DPHM and diphenylmethanol, were identified in the basic fraction, in addition to DPHM itself, which was present mainly as a conjugate. Even after enzymatic hydrolysis, DPHM could be detected for up to 24 h in camels after an i.v. dose of 0.625 mg/kg body weight.  相似文献   

12.
A cross-sectional investigation was made into the seroprevalence of brucellosis in camels in three arid and semi-arid camel-rearing regions of Ethiopia (Afar, Somali and Borena) between November 2000 and April 2001. When sera collected from 1442 accessible camels were screened with the Rose Bengal plate test (RBPT), 82 (5.7%) of them reacted. The results of a complement fixation test (CFT) on those sera that had given a positive reaction to the screening test then indicated a 4.2% prevalence of brucellosis in the tested camels. There was a significant difference in the prevalence of brucellosis (2 = 7.91, p<0.05), which was highest in Afar (5.2%) followed by Somali (2.8%) and Borena (1.2%) regions. Camels in Afar had a four times higher risk of brucellosis with an odds ratio (OR) of 4.34 (confidence interval, CI = 1.76–10.72, p<0.001) compared to the risk in Borena. Likewise, Afar had higher risk (OR = 1.76, 1.13–2.74, p<0.05) than that in Somali. There was no significant difference in seroprevalence between the sexes (p>0.05). Although a higher prevalence (6.3%) was observed in camels over 3 years old in Afar, there was no significant overall age difference (p>0.05).  相似文献   

13.
Florfenicol, a monofluorinated analogue of thiamphenicol, has a broad antibacterial spectrum. The pharmacokinetics of florfenicol was studied following a single intravenous (i.v.) or intramuscular (i.m.) injection at a dose of 20 mg/kg body weight in healthy male camels, sheep and goats. The concentration of florfenicol in plasma was determined using a microbiological assay. Pharmacokinetic analysis was performed using a two-compartment open model. Following i.m. administration, the maximum plasma concentration of florfenicol (C max) reached in camels, sheep and goats was 0.84±0.08, 1.04±0.10 and 1.21±0.10 g/ml, respectively, the the time required to reach C max (t max) in the same three respective species was 1.51±0.14, 1.44±0.10 and 1.21±0.10 h. The terminal half-life (t 1/2) and the fraction of the drug absorbed (F%) in camels, sheep and goats were 151.3±16.33, 137.0±12.16 and 127.4±11.0 min, and 69.20%±7.8%, 65.82%±6.7% and 60.88%±5.9%, respectively. The MRT in the same three respective species was 4.01±0.45, 3.42±0.39 and 2.98±0.32 h. Following i.v. administration, the terminal half-life (t 1/2) and total body clearance (ClB) in camels, sheep and goats were 89.5±9.2, 78.8±8.3 and 71.1±8.9 min and 0.33±0.04, 0.30±0.03 and 0.27±0.03 L/h per kg, respectively. The area under the curve (AUC0–) and the mean residence time (MRT) in the same three respective species were 60.61±6.98, 62.45±6.56 and 74.07±7.85 g/ml per h, and 2.71±0.31, 2.34±0.25 and 2.11±0.23 h. These data suggest that sheep and goats absorb and clear florfenicol to a broadly similar extent, but the rate and extent of absorption of the drug tends to be higher in camels. Drug treatment caused no clinically overt adverse effects. Plasma enzyme activities and metabolites indicative of hepatic and renal functions measured 1, 2, 4 and 7 days following the drug treatment were within the normal range, indicating that the drug is safe at the dose used.  相似文献   

14.
The overall prevalence rate of Cephalopina titillator in 778 slaughtered camels was 71.7%, 55% in males and 85% in females. The mean larval counts in infested camels were 26.7±25.9 and 34.6±30.8, for males and females, respectively. There were highly significant differences (p<0.001) in the number of larvae in camels of different ages and sexes and also between the wet and dry seasons. The average time to pupate was 4.9±4.6 minutes, and the pupation period was 21±2.4 days. The major gross lesions observed were congestion of the pharyngeal mucosa with profuse secretions, and haemorrhage in early cases. In some cases, there were ulcer-like lesions and nodules, which contained pus. The dominant microscopic lesions were infiltration of the lamina propria by eosinophils, lymphocytes and macrophages, hyperplasia of the stratified squamous epithelium, necrotic changes in the mixed glands and desquamation of epithelial cells. A survey using questionnaires revealed that all the camel owners called the disease caused by infestation with C. titillator `Sengale' and that 87% of them considered that infestation with these larvae results in reduced milk production and body weight. The major clinical signs of the disease were sneezing and expulsion of larvae (68%), abnormal movement of the head (45%), grooming (44%), nasal discharge (40%), poor appetite (26.7%), difficulty in breathing (18%), and sometimes bleeding from the nostrils (18%) and coughing (27%).  相似文献   

15.
Trifoliate left atrioventricular (AV) valve with common atrioventricular junction is considered part of the spectrum of atrioventricular septal defect. This valve morphology is typically associated with defects in the AV septum resulting in communication at the atrial or ventricular level, but has also been described as an isolated defect in the setting of a common AV junction without AV septal defect. Trifoliate left AV valve exhibits a line of apposition between the bridging leaflets that is directed toward the inlet interventricular septum, distinguishing it from isolated mitral valve cleft in which the orientation of the bridging leaflets are toward the left ventricular outflow tract. The echocardiographic findings of four dogs with trifoliate left AV valve are described; two with intact septal structures and two with large ostium primum defects. Three dogs underwent open surgical repair using different approaches depending on the presence or absence of a septal defect. One of these underwent concurrent surgical repair for right AV valve dysplasia. One dog with intact septal structures underwent interventional closure of a concurrent patent ductus arteriosus. Current terminology associated with trileaflet left AV valve malformations is reviewed.  相似文献   

16.
The productivity and the prevalence rates of the major parasites of camels (Camelus dromedarius) kept under traditional management conditions at Errer valley, Ethiopia were assessed for a year (October 1997–September 1998). The daily milk offtake was significantly higher (p<0.05) during the wet season (3.12±0.03 L) than during the dry season (1.49±0.04 L). Likewise, significantly higher (p<0.05) daily weight gains (50.68±0.54 g) were observed during the wet season than during dry season in immature camels aged 1–4 years. Trypanosoma evansi, Sarcoptes scabiei and strongyle parasites were present throughout the year, but their prevalence rates were higher during the rainy months than during the dry months. The minimum and maximum point prevalence rates for T. evansi were 5.4% and 20.6%, respectively. Similarly, the point prevalence rates for S. scabiei also varied from 4.7% during the dry season to 21.7% during the rainy months. The highest strongyle egg counts per gram of faeces and highest point prevalence rate (85.7%) were observed in October, a rainy month, whereas the lowest number of eggs per gram of faeces and the lowest point prevalence rate (61.5%) were recorded in April, a dry month.  相似文献   

17.
The aim of present study was to determine the origin, distribution and course of the coronary arteries in Bactrian camels. Ten hearts of adult healthy Bactrian camels of different sex constituted the material. Following exposition of the arteries by means of injection of 15% ABS coloured with red carmine to a. coronaria sinistra and a. coronaria dextra, dissection was performed. The arterial vascularization of the heart in Bactrian camels was determined to be supplied by a. coronaria sinistra and a. coronaria dextra which originate from the aorta. The results showed that ramus interventricularis subsinuosus is one branch of a. coronaria dextra in Bactrian camels, which is characteristic of a. coronaria dextra pattern. Ramus septi interventricularis that supplied the interventricular septum mainly originates from ramus interventricular paraconalis. Two muscular bridges ware observed crossing ramus interventricular paraconalis in the middle third of sulcus interventricularis paraconalis. Muscular bridge was not found above ramus interventricularis subsinuosus in this study.  相似文献   

18.
A nine-and-a-half-year-old dog was referred for investigation of bradycardia after being hit by a car. Electrocardiography revealed a third degree atrioventricular (AV) block. The dog died during a syncopal attack. Post mortem examination revealed an atrial septal tear with haemorrhage and myocardial degeneration affecting the AV bundle.  相似文献   

19.
M-mode echocardiographic structures, and cardiac function indices, PCV, and total plasma protein values were determined for 34 endurance equine athletes before (base line) and after (after race) a 161-km endurance competition and were compared. The PCV (base-line mean, 37%; after-race mean, 46%) and total plasma protein value (base-line mean, 6.9 g/dl; after-race mean, 7.5 g/dl) increased. Compared with base-line echocardiography, after-race echocardiography indicated an increase in heart rate, as determined from the simultaneous ECG recorded on the echocardiograph (base-line mean, 41 beats/min; after-race mean, 54 beats/min), and an increase in interventricular septal diastolic thickness (base-line mean, 28 mm; after-race mean, 33 mm). The septal thickening fraction (base-line mean, 59%; after-race mean, 38%), the left atrioventricular valve E to F slope (base-line mean, 224 mm/s; after-race mean, 175 mm/s), the left ventricular diastolic dimension (base-line mean, 99 mm; after-race mean, 86 mm), the fractional shortening of the left ventricle (base-line mean, 41%; after-race mean, 37%), the aortic root dimension (base-line mean, 63 mm; after-race mean, 58 mm), the caudal aortic wall excursion (base-line mean, 19 mm; after-race mean, 11 mm) and the left atrial diastolic dimension (base-line mean, 46 mm; after-race mean, 39 mm), decreased significantly (P less than 0.05). In base-line echocardiographs, late diastolic left atrioventricular valve motion was evident in 9 horses. The aberrant left atrioventricular valve motion was not evident in after-race echocardiographs. Seemingly, central vascular volume decreased in these horses during the recovery phase of severe strenuous endurance competition.  相似文献   

20.
Third degree atrioventricular (AV) block in dogs is thought to be most frequently characterized by non-specific fibrotic changes in the AV node. However, it may occur secondary to an undiagnosed inflammatory process. We report a case of third degree AV block in a dog, secondary to acute lymphocytic-plasmacytic myocarditis that resulted in sudden death. This dog had cardiac troponin I levels of 44.65 ng/mL (normal <0.11 ng/mL). The serum cardiac troponin I level was five times higher than any other AV block patient measured in our laboratory, and was also substantially higher than in dogs with chronic valve disease or dilated cardiomyopathy. The severe myocardial necrosis observed at necropsy correlated with the degree of cardiac troponin I elevation. This report suggests that measurement of cardiac troponin I may be an indicated test before pacemaker implantation in dogs with third degree AV block.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号