RESUMEN
It was the purpose of the present study to determine (1) whether or not there exists a common respiratory and cardiac cycle time effect of the baroreceptor control of heart rate (HR) and blood pressure (BP) in spontaneously breathing anaesthetized dogs and (2) whether this effect, if present, is abnormal in dogs with renal hypertension. The baroreflex responses were evoked by brief low-intensity electrical carotid sinus nerve stimulation (CSNS) triggered by the R-wave in the electrocardiogram with an adjustable delay (0-210 ms) and positioned in either inspiration or expiration. All baroreceptor afferent nerves were intact. Brief CSNS had no noticeable effect on breathing. The responses of means of HR, respiratory sinus arrhythmia (RSA), and systolic and diastolic respiratory blood pressure waves (RBPWsyst, RBPWdiast) to CSNS were not different for normotensive and hypertensive dogs. No cardiac, but a small respiratory cycle time effect on means of HR, BPsyst and BPdiast was observed. The magnitude of RSA and RBPWdiast was markedly enhanced for expiratory CSNS at each delay after the R-wave. Inspiratory CSNS diminished the magnitude of RSA and RBPW only if applied during systole, and become ineffective for delays greater than 200 ms after the R-wave. During both respiratory phases, CSNS was elevated at times of central presentation of the natural sinoaortal baroreceptor discharges (120 ms and 70 ms, respectively). The magnitudes of RSA and RBPW were influenced simultaneously and in the same way by CSNS throughout. It is concluded that, under the present experimental conditions, RSA and RBPW have a common central origin.
Asunto(s)
Presión Sanguínea , Seno Carotídeo/inervación , Frecuencia Cardíaca , Corazón/fisiopatología , Hipertensión Renal/fisiopatología , Respiración , Animales , Perros , Estimulación Eléctrica , Femenino , Corazón/fisiología , Masculino , Valores de ReferenciaRESUMEN
Electrical stimulation of the posterior cricoarytenoid muscle, synchronized with inspiration, was achieved in dogs utilizing a radio frequency stimulus triggered by a chest wall expansion transducer. This system brings about abduction of the paralyzed vocal cord for the entire duration of inspiration, which allows a normal flow of air through the larynx. The implantable part of that system was tested successfully in chronic experiments (up to 11 months) in dogs with experimental paralysis of the recurrent laryngeal nerve. We feel that the system may be suitable for pacing the paralyzed human larynx.
Asunto(s)
Terapia por Estimulación Eléctrica/instrumentación , Parálisis de los Pliegues Vocales/terapia , Animales , Perros , Electrodos Implantados , Músculos Laríngeos/patología , Factores de Tiempo , Transductores , Parálisis de los Pliegues Vocales/patologíaRESUMEN
Respiratory sinus arrhythmia (RSA), systolic and diastolic respiratory blood pressure waves (RBPWsyst, RBPWdiast), mean heart rate (HR), mean respiratory frequency (RF) and the heart beat to respiratory cycle ratio (HB/RC) were measured in 23 spontaneously breathing, normotensive or renal hypertensive dogs under light anaesthesia. No significant differences were found between conditions of normal and chronically elevated blood pressure. All these parameters were analyzed statistically by means of linear regression analysis and rank correlation coefficient (rs). A correlation was found to exist between RSA and mean systolic blood pressure (negative), RF (negative), RBPWsyst (positive), RBPWdiast (positive). RF correlated with both HB/RC (negative) and RBPWsyst (negative). A correlation was also seen between PA and both BPsyst (positive) and BPdiast (positive), BPsyst and BPdiast (positive) and between HR and RBPWdiast (negative); however, all the remaining, theoretically possible correlations were not significant. The results may be referred to resonance mechanisms in a common nervous oscillator system.
Asunto(s)
Presión Sanguínea , Frecuencia Cardíaca , Hipertensión Renal/fisiopatología , Respiración , Animales , Arritmia Sinusal/fisiopatología , Perros , Femenino , Masculino , PeriodicidadRESUMEN
The effect on the amplitudes of RSA and RBPW of the time of the stimulus in the cardiac cycle, and also of continuous stimulation were studied. When the stimulus train was applied near peak systole the amplitudes of RSA and RBPW decreased. Stimulation in late systole increased both RSA and RBPW. Continuous stimulation did not exert any effects on RSA and RBPW.
Asunto(s)
Arritmia Sinusal/fisiopatología , Presión Sanguínea , Seno Carotídeo/fisiología , Respiración , Animales , Perros , Femenino , Frecuencia Cardíaca , MasculinoRESUMEN
Electrical stimulation of the posterior cricoarytenoid muscle, synchronized with inspiration, was achieved in dogs, utilizing a radio frequency stimulus triggered by a chest wall expansion transducer. This system brings about the abduction of the paralyzed vocal cord for the entire duration of inspiration, which allows a normal flow of air through the larynx. The stimulation system could be tested successfully in actual experiments in dogs with artificial paralysis of the recurrent laryngeal nerve. Its effectiveness could be proved through observation of the vocal cord movements (photographic documentation) and recording subglottic pressure variations. Transmission of stimulation energy is effected by electrical induction.
Asunto(s)
Disnea/terapia , Terapia por Estimulación Eléctrica/métodos , Respiración , Parálisis de los Pliegues Vocales/terapia , Animales , Perros , Músculos Laríngeos/fisiopatología , Nervio Laríngeo Recurrente/fisiopatología , Parálisis de los Pliegues Vocales/fisiopatologíaRESUMEN
Patients with bilateral paresis of the recurrent laryngeal nerves have primarily breathing difficulties. But on the other hand the common operations for widening the glottis produce voice problems. To overcome these difficulties a muscle stimulation device was developed, which is triggered by the inspiratory motion of the thorax. With this device impulses are transmitted by radiofrequency from a transmitter located outside the body to a receiver implanted into subcutaneous tissue of the neck and thence by electrode wires to the posterior cricoarytenoid muscle (PCA). In the dogs with one cut recurrent laryngeal nerve the paralyzed vocal cord (VC) moved regularly with abductions at inspiration by stimulating the PCA. The efficiency of that stimulating device was proved by taking photographs of the VC-motion and by recording the subglottal air pressure changes.
Asunto(s)
Músculos Laríngeos/fisiopatología , Músculos/fisiopatología , Respiración , Parálisis de los Pliegues Vocales/fisiopatología , Animales , Perros , Estimulación Eléctrica/instrumentación , Parálisis de los Pliegues Vocales/terapiaRESUMEN
Both carotid sinus nerves of anesthetized, spontaneously breathing dogs were stimulated, before and after dissection, with brief, R-wave-triggered, submaximal electric impulses during different phases of the heart cycle. The resulting decrease of blood pressure and heart rate, related to the initial level and stimulation intensity is, respectively, about 2.5- and 4.5fold higher after denervation. Stimuli applied 90 ms after the R-wave provoke maximal lowering of mean arterial pressure. After dissection this maximum reappears, enhanced by the factor of 1.4, with stimuli delayed by 70 ms. Also, the initial decrease of heart rate in the first respiration cycle after onset of stimulation shows a maximum of 90 ms, which does not, however, change its position after dissection. Two mechanisms are discussed for the heart cycle related sensitivity of the pressor-receptor reflex: 1. Time-selective inhibition of the sympathetic activity controlling the smooth vascular muscles because of a central coincidence of the afferent signals from the sinus and aorta nerves with the electric stimuli, and 2. the heart cycle related sensitivity of the heart against efferent vagal control signals.