Parasympathetic postganglionic pathways to the sinoatrial node

Vagal ganglia that innervate the canine sinoatrial node (SAN) have been localized to a fat pad overlying and surrounding the right pulmonary vein complex (PVFP). The ventral epicardial surface of the right atrium was mapped in seven dogs anesthetized with alpha-chloralose after beta-blockade (timolol) and cardiac sympathetic and parasympathetic decentralization. A small, concentric bipolar exploring electrode was used to stimulate (during the atrial refractory period and using trains of five to eight stimuli per beat) systematically in the epicardial regions between the PVFP and the SAN. Changes in SAN rate with stimulation were measured, and the anatomic location was identified on a 150-point grid fitted to conform to size and shape of the atrium. Mapping was performed before and after local (PVFP) and systemic ganglionic blockade (hexamethonium). Data reveal that the primary vagal postganglionic pathways to the sinoatrial nodal region are subepicardial and adjacent to the SAN artery along the sulcus terminalis. Hexamethonium in the PVFP abolishes SAN inhibition during preganglionic vagal excitation, without interrupting vagal suppression of atrioventricular conduction. However, SAN slowing (with varying attenuation) continued to occur after hexamethonium (either PVFP or systemically) when the exploring electrode was applied directly over intramural postganglionic fibers between PVFP and sinus node. Attention is directed to existence of a very few synapses closer to SAN, probably in isolated ganglia immersed in fatty connective tissues along the sulcus terminalis.

Download Full-text

Efferent vagal innervation of canine ventricle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.248.1.h89 ◽

1985 ◽

Vol 248 (1) ◽

pp. H89-H97 ◽

Cited By ~ 13

Author(s):

N. Takahashi ◽

M. J. Barber ◽

D. P. Zipes

Keyword(s):

Coronary Artery ◽

Vagal Stimulation ◽

Left Ventricular ◽

Constant Infusion ◽

Epicardial Surface ◽

Before And After ◽

Vagal Innervation ◽

The Subject ◽

Infusion Of Norepinephrine ◽

The Right

The route efferent vagal fibers travel to reach the left ventricle is not clear and was the subject of this investigation. We measured left ventricular and septal effective refractory period (ERP) changes during vagal stimulation and a constant infusion of norepinephrine, before and after phenol was applied at selected sites of the heart to interrupt efferent vagal fibers that may be traveling in that area. Phenol applied to the atrioventricular (AV) groove between the origin of the right coronary artery anteriorly to the posterior descending branch of the circumflex coronary artery completely eliminated vagal-induced prolongation of ERP in the anterior and posterior left ventricular free wall and reduced, but did not eliminate, ERP prolongation in the septum. A large (3-cm radius) epicardial circle of phenol prevented vagal-induced ERP prolongation within the circle in all dogs, while a small (1-cm radius) epicardial circle of phenol failed to prevent vagal-induced ERP changes within the circle in any dog. An intermediate (2-cm radius) circle eliminated vagal effects on ERP in 13 of 18 dogs. Arcs of phenol, to duplicate the upper portion of the circle, applied sequentially from apex to base eliminated efferent vagal effects only when painted near or at the AV groove. We conclude that the majority of efferent vagal fibers enroute to innervate the anterior and posterior left ventricular epicardium cross the AV groove within 0.25-0.5 mm (depth of phenol destruction) of the epicardial surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Sevoflurane Has No Effect on Sinoatrial Node Function or on Normal Atrioventricular and Accessory Pathway Conduction in Wolff-Parkinson-White Syndrome during Alfentanil/Midazolam Anesthesia

Anesthesiology ◽

10.1097/00000542-199901000-00010 ◽

1999 ◽

Vol 90 (1) ◽

pp. 60-65 ◽

Cited By ~ 33

Author(s):

Michael D. Sharpe ◽

Daniel J. Cuillerier ◽

John K. Lee ◽

Magdi Basta ◽

Andrew D. Krahn ◽

...

Keyword(s):

Cycle Length ◽

Sinoatrial Node ◽

Sinus Node ◽

Accessory Pathway ◽

Atrioventricular Node ◽

Conduction Time ◽

White Syndrome ◽

The Right ◽

Ablative Procedures ◽

Wolff Parkinson White Syndrome

Background The effects of sevoflurane on the electrophysiologic properties of the human heart are unknown. This study evaluated the effects of sevoflurane on the electrophysiologic properties of the normal atrioventricular conduction system, and on the accessory pathways in patients with Wolff-Parkinson-White syndrome, to determine its suitability as an anesthetic agent for patients undergoing ablative procedures. Methods Fifteen patients with Wolff-Parkinson-White syndrome undergoing elective radiofrequency catheter ablation were studied. Anesthesia was induced with alfentanil (20-50 microg/kg) and midazolam (0.15 mg/kg), and vecuronium (20 mg) and maintained with alfentanil (0.5 to 2 microg x kg(-1) x min(-1)) and midazolam (1 or 2 mg every 10-15 min, as required). An electrophysiologic study measured the effective refractory period of the right atrium, atrioventricular node, and accessory pathway; the shortest conducted cycle length of the atrioventricular node and accessory pathway during atrial pacing; the effective refractory period of the right ventricle and accessory pathway; and the shortest retrograde conducted cycle length of the accessory pathway during ventricular pacing. Parameters of sinoatrial node function included sinus node recovery time, corrected sinus node recovery time, and sinoatrial conduction time. Intraatrial conduction time and the atrial-His interval were also measured. Characteristics of induced reciprocating tachycardia, including cycle length, atrial-His, His-ventricular, and ventriculoatrial intervals, also were measured. Sevoflurane was administered to achieve an end-tidal concentration of 2% (1 minimum alveolar concentration), and the study measurements were repeated. Results Sevoflurane had no effect on the electrophysiologic parameters of conduction in the normal atrioventricular conduction system or accessory pathway, or during reciprocating tachycardia. However, sevoflurane caused a statistically significant reduction in the sinoatrial conduction time and atrial-His interval but these changes were not clinically important. All accessory pathways were successfully identified and ablated. Conclusions Sevoflurane had no effect on the electrophysiologic nature of the normal atrioventricular or accessory pathway and no clinically important effect on sinoatrial node activity. It is therefore a suitable anesthetic agent for patients undergoing ablative procedures.

Download Full-text

Supersensitivity to l-norepinephrine of the denervated sinoatrial node

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1965.208.2.255 ◽

1965 ◽

Vol 208 (2) ◽

pp. 255-259 ◽

Cited By ~ 15

Author(s):

David E. Donald ◽

John T. Shepherd

Keyword(s):

Vagus Nerve ◽

Sinoatrial Node ◽

Sinus Node ◽

Sympathetic Nerves ◽

Cardiac Denervation ◽

Cervical Vagotomy ◽

Cervical Ganglia ◽

The Right ◽

Cardiac Nerves ◽

Stimulation Of

Following attempted denervation of the heart by the technic of regional neural ablation, dogs with incomplete cardiac denervation were shown to have the same supersensitivity to l-norepinephrine as dogs in which the denervation of the heart was complete. Dogs with chronic bilateral stellate ganglionectomy or those pretreated with reserpine had cardiac acceleration in response to the administration of tyramine or to stimulation of the stellate cardiac nerves, but did not demonstrate supersensitivity to l-norepinephrine. No supersensitivity was seen in dogs with chronic bilateral cervical vagotomy. Excision of the right stellate and caudal cervical ganglia and the immediately adjacent right vagus nerve resulted in supersensitivity to l-norepinephrine. In these animals cardiac acceleration resulted from stimulation of the left stellate cardiac nerves or from the administration of tyramine. The supersensitivity was lost after excision of the sinoatrial node. It is concluded that one can uniquely denervate the sinus node and that dogs so treated will develop supersensitivity to l-norepinephrine despite the presence of functional sympathetic nerves to the rest of the heart.

Download Full-text

Effects of alpha-adrenergic blockade on coronary autoregulation in dogs

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.253.2.h365 ◽

1987 ◽

Vol 253 (2) ◽

pp. H365-H372

Author(s):

C. E. Jones ◽

I. Y. Liang ◽

P. A. Gwirtz

Keyword(s):

Coronary Flow ◽

Myocardial Oxygen Consumption ◽

Pressure Range ◽

Closed Loop ◽

Beta Blockade ◽

Adrenergic Blockade ◽

Loop Gain ◽

Before And After ◽

Alpha Blockade ◽

Alpha Chloralose

In alpha-chloralose-anesthetized, open-chest dogs, left coronary blood flow and oxygen extraction were measured at perfusion pressures from 25 to 175 mmHg. Pressure-flow relationships were obtained before and after alpha-blockade with prazosin or alpha 2-blockade with yohimbine in the presence of beta-blockade with propranolol. The efficiency of flow autoregulation with increments in pressure was calculated as the closed-loop gain and as the slope of flow to pressure. In all animals the highest gain and the lowest slope were seen when pressure increased from 75 to 125 mmHg. In the prazosin group before alpha-blockade the gain with this pressure increase was 0.76 +/- 0.05, whereas in the yohimbine group before alpha-blockade this gain was 0.75 +/- 0.03. Prazosin reduced the gain within the pressure range of 75–125 mmHg by 41%, and this reduction was statistically significant (P less than 0.05). Prazosin also significantly increased the flow to pressure slope within this range. In addition, at all pressures greater than or equal to 50 mmHg, the level of coronary flow was significantly increased by prazosin. The increase in flow and the reduction in autoregulatory efficiency with prazosin were not attributable to an increase in myocardial oxygen consumption. Yohimbine had no effects on the level of coronary flow or on the autoregulatory efficiency. These data indicate that an alpha 1-adrenoceptor mediated coronary constriction modulates coronary autoregulation.

Download Full-text

Adrenergic mechanisms in canine gastric circulation

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.4.977 ◽

1975 ◽

Vol 229 (4) ◽

pp. 977-982 ◽

Cited By ~ 13

Author(s):

MJ Zinner ◽

JC Kerr ◽

DG Reynolds

Keyword(s):

Left Gastric Artery ◽

Beta Blockade ◽

Adrenergic Blockade ◽

Adrenergic Stimulation ◽

Beta Adrenergic ◽

Before And After ◽

Anesthetized Dogs ◽

Gastric Circulation ◽

Flow Through ◽

The Right

The effects of adrenergic stimulation and blockade on the gastric circulation were studied in anesthetized dogs. Blood flow through the right and left gastric artery was measured electromagnetically. Norepinephrine and isoproterenol were injected intra-arterially and intravenously before and after alpha- and beta-adrenergic blockade. Isoproterenol caused vasodilation of both right and left gastric circulations and this effect was attenuated by beta blockade. Epinephrine and norepinephrine induced constriction followed by dilation in both circulations. The constrictor components were attenuated or abolished by alpha-adrenergic blockade and the dilator components were attenuated by beta-adrenergic blockade. The right and left gastric vascular beds demonstrated quantitatively different responses to the same dose of each adrenergic amine. The left gastric circulation had a greater vasodilator response than did the right gastric circulation. These data support the classical concepts that epinephrine and norepinephrine are "mixed" adrenergic agonists and isoproterenol is a "pure" beta-adrenerigic agonist. The data further suggest that there is a differential in beta-adrenergic receptor distribution with the left gastric vasculature demonstrating greater dilator responses than the right.

Download Full-text

Comparative Arterial Antithrombotic Activity of Clopidogrel and Acetyl Salicylic Acid in the Pig

Thrombosis and Haemostasis ◽

10.1055/s-0038-1646307 ◽

1992 ◽

Vol 68 (05) ◽

pp. 500-505 ◽

Cited By ~ 32

Author(s):

Ch M Samama ◽

Ph Bonnin ◽

M Bonneau ◽

G Pignaud ◽

E Mazoyer ◽

...

Keyword(s):

Platelet Aggregation ◽

Femoral Artery ◽

Bleeding Time ◽

Ex Vivo ◽

Flow Reduction ◽

Cyclic Flow ◽

Left Femoral Artery ◽

Before And After ◽

The Right ◽

Induced Aggregation

SummaryWe investigated the comparative antithrombotic properties of clopidogrel, an analogue of ticlopidine, and aspirin, using the Folts' model on femoral arteries in 22 pigs. On each animal, clopidogrel or aspirin were used to treat the thrombotic process on the left femoral artery and to prevent this process on the right femoral artery. Sequentially: an injury and stenosis were carried out on the left femoral artery; the thrombotic process was monitored with a Doppler during a 30-min observation period for cyclic flow reductions or permanent cessation of flow; after the first cyclic flow reduction occurred, clopidogrel (5 mg kg-1) or aspirin (2.5, 5, 100 mg kg-1) were injected intravenously; if cyclic flow reductions were abolished, epinephrine (0.4 µg kg-1 min-1) was injected to try to restore cyclic flow reductions and/or permanent cessation of flow; then injury and stenosis were applied on the right femoral artery. Before and after injection of clopidogrel or aspirin, ear immersion bleeding times and ex-vivo platelet aggregation were performed. Clopidogrel (n = 7) abolished cyclic flow reductions in all animals and epinephrine did not restore any cyclic flow reduction. On the right femoral artery, cyclic flow reductions were efficiently prevented, even for two injuries. Basal bleeding time (5 min 28) was lengthened (>15 min, 30 min after clopidogrel and remained prolonged even after 24 h). ADP-induced platelet aggregation was inhibited (more than 78%). Comparatively, aspirin had a moderate and no dose-dependent effect. Aspirin 2.5 mg kg-1 (n = 6) abolished cyclic flow reductions in 2 animals, CFR reoccurred spontaneously in one animal and epinephrine restored it in a second animal. Aspirin 5 mg kg-1 (n = 6) abolished cyclic flow reductions in only 3 animals and epinephrine always restored it. Aspirin 100 mg kg-1 (n = 3) was unable to abolish cyclic flow reductions. On the right femoral artery, aspirin did not significantly prevent cyclic flow reductions which occurred in all animals after one (n = 14) or two injuries (n = 1), except for one animal. Basal bleeding time was lengthened but it shortened rapidly, reaching its basal value after 24 h. ADP-induced aggregation was not significantly inhibited, whereas arachidonic acid induced aggregation was always inhibited. Clopidogrel appears as a more potent antithrombotic drug than aspirin in this model, in treating and preventing spontaneous or epinephrine-induced cyclic flow reductions and lengthening bleeding time.

Download Full-text

EFEKTIVITAS METODE DEMONSTRASI DALAM MENINGKATKAN HASIL BELAJAR SISWA SEKOLAH MENENGAH KEJURUAN PADA PENGAJARAN SISTEM KOLOID

JURNAL PENELITIAN BIDANG PENDIDIKAN ◽

10.24114/jpp.v19i1.3044 ◽

2013 ◽

Vol 19 (1) ◽

pp. 28

Author(s):

Hamda Situmorang ◽

Manihar Situmorang

Keyword(s):

High School ◽

High School Students ◽

Abstract Concept ◽

Vocational High School ◽

School Students ◽

Lecture Method ◽

Colloid System ◽

Before And After ◽

The Right ◽

And Control

Abstract Implementation of demonstration method in the teaching of chemistry is assigned as the right strategy to improve students’ achievement as it is proved that the method can bring an abstract concept to reality in the class. The study is conducted to vocational high school students in SMKN1 Pargetteng getteng Sengkut Pakfak Barat at accademic year 2013. The teaching has been carried out three cycles on the teaching of chemistry topic of colloid system. In the study, the class is divided into two class, experiment class and control class. The demontration method is used to teach students in experimental class while the teaching in control class is conducted with lecture method. Both are evaluated by using multiple choise tests before and after the teaching procedures, and the ability of students to answer the problems are assigned as students’ achievements. The results showed that demonstration method improved students’ achievement in chemistry. The students in experimental class who are taughed with demonstration method (M=19.08±0.74) have higher achievements compare with control class (M=12.91±2.52), and both are significantly different (tcalculation 22.85 > ttable 1.66). The effectivity of demostration method in experimental class (97%) is found higer compare to conventional method in control class (91%).

Download Full-text

EDUKASI TERHADAP REMAJA DALAM PENINGKATAN PENGETAHUAN TENTANG PENGGUNAAN GAME DENGAN BIJAK

Jurnal Pemberdayaan Masyarakat Universitas Al Azhar Indonesia ◽

10.36722/jpm.v2i1.361 ◽

2020 ◽

Vol 2 (1) ◽

pp. 11

Author(s):

Ikhsan Fuady ◽

Rangga Saptya MP

Keyword(s):

Side Effects ◽

Violent Behavior ◽

Daily Lives ◽

Before And After ◽

Improper Use ◽

Effective Role ◽

Education And Outreach ◽

The Right ◽

Dedicated Team ◽

User Ratings

AbstrakPemanfaatan game dikalangan remaja memiliki peran yang efektif sebagai wadah untuk hiburan. Tetapi pemanfaatan game tidak tepat memiliki efek samping game terhadap kehidupan sehari hari remaja, mulai dari kurang bersosialIsasi hingga perilaku kekerasan dikalangan remaja. Penyuluhan terhadap remaja bertujuan untuk memberikan pemahaman kepada remaja tentang variasi game berdasarkan rating pengguna, maupun cerdas dalam manajemen penggunaan game dalam kehidupan remaja sehari hari. Pengetahuan remaja tentang varian/ragam game berdasarkan rating relatif rendah sebagaian besar pemengetahuannya tersebar pada kategori sangat rendah dan rendah yaitu sebesar 65 persen. Metode edukasi dan sosialisasi ini adalah dengan beberapa tahapan. Tahap pertaman tim pengabdian memberikan edukasi dan diskusi tentang beragam bentuk game, karakteristik, serta karakteristik pengguna game yang tepat. Selanjutnya beberapa permainan dan kuis untuk meingkatkan literasi remaja tentang pemanfaatan game secara bijak. Kegiatan penyuluhan ini mampu meningkatkan pemahaman para remaja dalam mengenali game yang baik digunakan, hal ini dapat dilihat dari peningkatan pengetahuan remaja relatif signifikan sebelum dan sesudah penyuluhan.Kata kunci: Edukasi, Game, Penyuluhan Abstract The use of games among teenagers has an effective role as a forum for entertainment. But the improper use of games has the side effects of games on the daily lives of adolescents, ranging from lack of socialization to violent behavior in adolescents. Counseling against adolescents aims to provide understanding to adolescents about the variety/variance of games based on user ratings, as well as being smart in managing game use in daily teenage life. Teenagers' knowledge about game variants/based on the rating is relatively low, most of the knowledge is spread in the very low and low categories, which is 65 percent. The method of education and outreach is by several stages. The first stage of the dedicated team provided education and discussion about various forms of games, characteristics, and characteristics of the right game user. Furthermore, some games and quizzes to improve teen literacy about game use wisely. This counseling activity can increase the understanding of teenagers in recognizing games that are well used, this can be seen from the relatively significant increase in adolescent knowledge before and after counseling.Keywords: Education, Games, Counseling

Download Full-text

Smartphone addiction and the relationship with head and neck pain and electromiographic activity of masticatory muscles

Work ◽

10.3233/wor-203398 ◽

2021 ◽

pp. 1-8

Author(s):

Fabiana Foltran Mescollotto ◽

Érica Brito Gonçalves ◽

Ester Moreira de Castro Carletti ◽

Ana Beatriz Oliveira ◽

Elisa Bizetti Pelai ◽

...

Keyword(s):

College Students ◽

Neck Pain ◽

Head And Neck ◽

Muscle Activity ◽

Neck Region ◽

Masticatory Muscles ◽

Smartphone Addiction ◽

Before And After ◽

Smartphone Use ◽

The Right

Background: Excessive use of smartphones may be associated with behavioral and physical health changes and might cause musculoskeletal alterations in the head and neck region. Objective: To evaluate the prevalence of smartphone addiction in college students and its correlation with symptoms of head and neck pain and masticatory and trapezius muscle activity while resting, before and after smartphone use. Methods: Twenty university students participated in the study. They answered the Smartphone Addiction Scale and the Fonseca Anamnestic Index. Next, the participants were seated and prepared for electromyography through the placement of surface electrodes on the masseter, temporal, and trapezius muscles. Rest condition data were collected for 10 seconds before and after 30 minutes of smartphone use. Results: The results showed that 35% of the evaluated individuals were classified as smartphone addicted and 35% reported no head or neck pain in the previous 30 days. There was no association between smartphone use and head and neck pain. In the electromyography, there was an increase in RMS values after smartphone use in the right and left masseter muscles and the left trapezius. Conclusion: College students presented a high prevalence of smartphone addiction and head and neck pain, but these were not statistically associated. There was a change in muscle activity only in the right trapezius muscles before and after 30 minutes of smartphone use. These findings are contrary to the current belief that the use of smartphones correlates with pain in the neck region and changes in the electrical muscle activity, leading to fatigue in the cervical muscles.

Download Full-text

Mediastinal anatomical landmarks, their variants and tips for video-assisted thoracoscopic navigation during oesophageal extirpation

Surgical and Radiologic Anatomy ◽

10.1007/s00276-021-02820-8 ◽

2021 ◽

Author(s):

Sergey Dydykin ◽

Friedrich Paulsen ◽

Tatyana Khorobykh ◽

Natalya Mishchenko ◽

Marina Kapitonova ◽

...

Keyword(s):

Prone Position ◽

Anatomical Study ◽

Structural Features ◽

Posterior Mediastinum ◽

Visual Navigation ◽

Anatomical Landmarks ◽

Video Assisted ◽

Before And After ◽

Human Cadavers ◽

The Right

Abstract Purpose There is no systematic description of primary anatomical landmarks that allow a surgeon to reliably and safely navigate the superior and posterior mediastinum’s fat tissue spaces near large vessels and nerves during video-assisted endothoracoscopic interventions in the prone position of a patient. Our aim was to develop an algorithm of sequential visual navigation during thoracoscopic extirpation of the esophagus and determine the most permanent topographic and anatomical landmarks allowing safe thoracoscopic dissection of the esophagus in the prone position. Methods The anatomical study of the mediastinal structural features was carried out on 30 human cadavers before and after opening the right pleural cavity. Results For thoracoscopic extirpation of the esophagus in the prone position, anatomical landmarks are defined, their variants are assessed, and an algorithm for their selection is developed, allowing their direct visualization before and after opening the mediastinal pleura. Conclusion The proposed algorithm for topographic and anatomical navigation based on the key anatomical landmarks in the posterior mediastinum provides safe performance of the video-assisted thoracoscopic extirpation of the esophagus in the prone position.

Download Full-text