ABSTRACT
RESUMEN Introducción. El estudio de la anatomía funcional del miocardio helicoidal continuo permite visualizar su inicio y fin en el nacimiento de los grandes vasos. En nuestras investigaciones siempre hemos considerado que debía tener un punto de unión que permitiera su rotación helicoidal para cumplir los movimientos fundamentales de acortamiento-torsión (sístole) y alargamiento-destorsión (succión). Una vez encontrado, se le llamó fulcro cardíaco. Objetivos. Esta investigación tiene como objeto describir y entender la interrelación entre el fulcro cardíaco y el nódulo auriculoventricular de Aschoff-Tawara Material y métodos. Se utilizaron 31 corazones procedentes de la morgue y del matadero: 17 correspondieron a bóvidos y 14 a seres humanos. Resultados. En nuestras investigaciones hemos demostrado que el soporte del miocardio, denominado fulcro cardíaco, que se localiza en el trayecto del segmento septal del anillo aórtico y se extiende desde el trígono izquierdo hasta el derecho por debajo del origen de la arteria coronaria derecha, es adyacente al nódulo auriculoventricular (AV). Otro aspecto importante de esta posición contigua es que el fulcro está rodeado, e incluso invadido, por un plexo nervioso interconectado con el nódulo. Conclusión. Esta descripción del fulcro cardíaco pondría fin al problema de la falta de apoyo del miocardio para cumplir su función de torsión/destorsión. La proximidad del fulcro al nódulo AV y la penetración de los plexos nerviosos en el apoyo indican la existencia de una unidad electromecánica, que hemos investigado en función de la anatomía helicoidal del corazón. Hemos comprobado una mejor estimulación cardíaca cuando el catéter se coloca en el infundíbulo ventricular derecho.
ABSTRACT Background. The functional anatomy of the helical, continuous myocardium allows envisioning that it initiates and ends at the origin of the great vessels. In our research, we have always considered that it should have a point of attachment to allow its helical rotation to fulfill the fundamental movements of shortening-torsion (systole) and lengthening-detorsion (suction), which once found, was called the cardiac fulcrum. Objectives. The research aims to describe the important aspect of understanding the interrelationship between the cardiac fulcrum and the Aschoff-Tawara atrioventricular node Material and Methods. A total of 31 hearts, arising from the morgue and slaughterhouse were used: 17 corresponded to bovids and 14 were human. Results. Our investigations have shown that the myocardial support termed cardiac fulcrum, located in the trajectory of the aortic annulus septal segment, extending from the left to the right trigone and below the origin of the right coronary artery, is adjacent to the AV node. Another important aspect of this contiguous position is that the fulcrum is surrounded, and even invaded, by a rich nervous plexus interconnected with the node. Conclusion. This description of the cardiac fulcrum would end the problem of lack of support of the myocardium to fulfill its function of torsion/detorsion. The proximity of the fulcrum to the AV node and the penetration of the nervous plexuses in the support suggest an electromechanical unit, which we have investigated according to the helical anatomy of the heart, establishing an improved cardiac stimulation with a catheter placed in the right ventricular outflow tract.
ABSTRACT
Treatment of supraventricular arrhythmia includes a wide range of medical interventions. Herbal remedies are suitable alternatives to synthetic drugs due to their availability, minimal side effects and lower price. Pharmacological studies and traditional medical literature point to the cardiovascular effects of Citrus aurantium L. (Rutaceae) in many instances. In the present study we used isolated perfused AV-node of rabbit as an experimental model to determine the effect of various concentrations of essential oil of C. aurantium (0.1-0.3 v/v) on the nodal conduction time and refractoriness of an isolated rabbit AV-nodal preparations. Selective stimulation protocols were used to independently quantify AV nodal recovery, facilitation and fatigue in 18 rabbits. Our results showed concentration-dependent and rate-independent suppressive effects of essence of C. aurantium on the Wenchebach cycle length (WBCL), AV Conduction Time (AVCT) and effective and functional refractory periods (ERP & FRP). Functional properties such as facilitation and fatigue were significantly increased by this plant. Citrus aurantium plays a protective role against the toxic effects of ouabaine by increasing AV nodal conduction time and refractoriness. The above results indicated differential effects of C. aurantium on slow and fast pathways, with a dominant role on fast pathways. This research has explained the protective role of C. aurantium on ouabaine toxicity. All results indicated the potential anti-arrhythmic effects of C. aurantium in treating supraventricular tachyarrhythmia.
El tratamiento de la arritmia supraventricular incluye una amplia gama de intervenciones médicas. Los remedios herbarios son alternativas adecuadas a las drogas sintéticas debido a su disponibilidad, con escasos efectos secundarios y bajo precio. Estudios farmacológicos y la literatura médica tradicional señalan los efectos cardiovasculares de Citrus aurantium L. (Rutaceae) en muchos casos. En el presente estudio se usaron aislados perfundidos del nodo AV de conejo como modelo experimental para determinar el efecto de diferentes concentraciones de aceite esencial de C. aurantium (0,1-0,3 v/v) sobre en el tiempo de conducción nodal y refractariedad. Un protocolo de estimulación selectiva se utilizó para cuantificar de forma independiente la recuperación, la facilitación y la fatiga del nodo AV en 18 conejos. Nuestros resultados muestran efectos supresores dependientes de la concentración e independiente de la velocidad de la esencia de C. aurantium sobre la duración del ciclo Wenchebach (WBCL), tiempo de conducción AV (AVTC) y períodos refractarios eficaz y funcional (PRE y PRF). Propiedades funcionales tales como la facilitación y la fatiga se incrementaron de manera significativa por esta planta. La Citrus aurantium juega un papel protector contra los efectos tóxicos de ouabaína al incrementar el tiempo de conducción AV nodal y la refractariedad. Los resultados indican efectos diferenciales de C. aurantium sobre las vías lentas y rápidas, con un papel dominante en las vías rápidas. Esta investigación ha explicado el papel protector de C. aurantium sobre la toxicidad ouabaine. Todos los resultados indican los posibles efectos anti-arrítmicos de C. aurantium en el tratamiento de taquiarritmias supraventriculares.
Subject(s)
Animals , Rabbits , Oils, Volatile/pharmacology , Citrus/chemistry , Atrioventricular Node , Ouabain/antagonists & inhibitors , Arrhythmias, Cardiac/drug therapy , Cardiac Electrophysiology , Ouabain/toxicity , Plant Preparations/pharmacology , Time FactorsABSTRACT
The AV node is a structure in the atrial septum at the atrioventricular junction. The atrial septum is important for various types of supravenricular arrgythmia especially for AV node reentrant tachycardia. In this study, it was aimed to understand the electrical propagation in the atrium and the atrial septum, as well as the effects of perinodal cryosurgery. Eleven mongrel dogs weighing between 26.0kg and 34.5kg were divided into control(d dogs) and cryosurgery(6 dogs) group. The animals were anesthetized with pentobarbital sodium(30 mg/kg) and under a normothermic total cardiopulmonary bypass, endocardial template electrodes(left atrium ; 124, right atrium; 128 bipolar electrodes) were placed into the both atria. The endocardial electrocal activation was recorded using a 256 channel computerized mapping system during normal sinus rhythm, atrial pacing, and ventricular pacing. For the cryosurgery group, the endocardial electrical activation was recorded after eight weeks of discrete perinodal cryosurgery. The results are as followings : 1) The electrical propagation from the SA node to the AV node occurred mainly through thick muscle band of the crista terminalis of the right atrium and anterior limbus fossa ovalis. 2) Electrophysiologically, the atrial septum appeared to be 2 layers. 3) During ventricular pacing, the center of the Koch triangle was the first to respond to activation. When the atrial septum of the AV nodal area was activated, the electrical activations propagated asymmetrically and the activity of the left atrium was propagated through the Bachmann's bundle. The left atrial side of the atrial septum was activated 10-15 msec later than the right side during ventricular pacing. 4) The cryosurgery did not change any significant difference in the AH, HV, AV node effective refractory period and AV node Wenckebach period. However, the ventriculo-atrial conduction was blocked in 50% of the animals. 5) In cryosurgery group, the electrical propagation from the SA nodal area to both atrial was similar to the control group except along side the vertical right atrial incision site. 6) The endocardial activation map in the cryosurgery group showed that the activation was spread out from the lateral atrial tissue outside of the cryolesions. The left atrial side of the atrial septum was was activated 6-19 msec later than the right atrial side. In conclusion, electrophysiologically the atrial septum appears to be composed of 2 layers and there is no direct electrical propagation between the AV node and the left atrial side of the atrial septum. The cryosurgery did not influence the electrial activation sequence from the SA node to the AV node except the site of cryolesion.