ABSTRACT
El reflejo de Bezold Jarisch es un reflejo cardioinhibitorio que juega un papel en la homeostasis cardiovascular. Consiste en la triada dada por hipotensión, bradicardia y vasodilatación periférica que puede ser desencadenada tanto por estímulos mecánicos, como químicos. Se considera que el mecanismo eferente contrarresta e inhibe los efectos del influjo simpático y, por el contrario, activa los efectos producidos por el sistema parasimpático. Durante la cirugía neurológica, la disminución de la presión intracraneal posterior a la extracción de colgajo óseo en la craneotomía, el uso de medicamentos osmóticos para disminuir el edema cerebral e incluso la posición del paciente durante el procedimiento suponen situaciones más propensas a la aparición del reflejo.
The Bezold Jarisch reflex is a cardioinhibitory reflex that plays a role in cardiovascular homeostasis. It consists of a triad given by hypotension, bradycardia, and peripheral vasodilation that can be triggered by both mechanical and chemical stimuli. The efferent counteracting mechanism is considered to inhibit the effects of sympathetic influx and, conversely, activates the effects produced by the parasympathetic system. During neurological surgery, the decrease in intracranial pressure after bone flap extraction in the craniotomy, the use of osmotic medications to decrease cerebral edema and even the position of the patient during the procedure supposes situations more prone to reflex appearance
Subject(s)
Reflex , Brain Edema , Intracranial Pressure , Craniotomy , NeurosurgeryABSTRACT
Abstract Background and objectives Ischemic cardiomyopathy is characterized by imbalance between supply and demand of myocardial oxygen. Endoscopic transthoracic sympathectomy is a therapeutic option indicated in refractory cases. However, the patient's position on the operating table may favor ischemic coronary events triggering the Bezold-Jarisch reflex. Case report A female patient, 47 years old, with refractory ischemic cardiomyopathy, admitted to the operating room for endoscopic transthoracic sympathectomy, developed the Bezold- Jarisch reflex with severe bradycardia and hypotension after placement in semi-sitting position to the procedure. Conclusion Bradyarrhythmia, hypotension, and asystole are complications potentially associated with patient placement in a semi-sitting position, particularly in cases with previous ischemic heart disease.
Resumo Justificativa e objetivos A cardiomiopatia isquêmica caracteriza-se pelo desbalanço entre a oferta e o consumo de oxigênio pelo miocárdio. A simpatectomia transtorácica endoscópica é uma opção terapêutica indicada nos casos refratários. Contudo, a posição do paciente na mesa cirúrgica pode favorecer eventos coronarianos isquêmicos e deflagrar o reflexo de Bezold-Jarisch. Relato de caso Paciente do sexo feminino, 47 anos, portadora de cardiomiopatia isquêmica refratária, admitida na sala de cirurgia para simpatectomia transtorácica endoscópica, deflagrou o reflexo de Bezold-Jarisch e desenvolveu bradicardia e hipotensão graves logo após colocação em posição semissentada para o procedimento. Conclusão Bradiarritmia, hipotensão e assistolia são complicações potencialmente associadas à colocação do paciente em posição semissentada, especialmente nos casos em que há prévio comprometimento isquêmico do coração.
Subject(s)
Humans , Female , Sympathectomy/methods , Bradycardia/etiology , Patient Positioning/adverse effects , Hypotension/etiology , Intraoperative Complications/etiology , Angina Pectoris/surgery , Reflex, Abnormal , Endoscopy , Respiratory Rate , Middle AgedABSTRACT
A doença valvular crônica de mitral é a enfermidade cardíaca mais comumente relatada em cães de pequeno e médio porte, adultos ou idosos. A síncope cardíaca é uma manifestação comumente observada, causada por diversos mecanismos. Objetivou-se relatar um caso desta doença em uma cadela da raça Teckel, com 16 anos de idade, que apresentava episódios recorrentes de síncope. Os episódios estavam associados com bradicardia, palidez de mucosas e aumento da pressão intratorácica. Excluindo-se outras causas de síncope, foi realizado o diagnóstico presuntivo de síncope neurocardiogênica, sendo a primeira descrição na medicina veterinária.
Chronic mitral valvular disease is the most commonly acquired heart disease in middle-aged to elderly dogs in small to medium-size breeds. Cardiac syncope is a common manifestation observed in such disease, caused by several mechanisms. The purpose of this study is to report a case of several syncope episodes in a Teckel dog aged 16 years, presenting chronic mitral valvular disease. The episodes were associated with bradycardia, pale mucous membranes and increased intra-thoracic pressure. The presumptive diagnosis of neurocardiogenic syncope was reached by excluding other causes of syncope, which is the first description in veterinary medicine.
La enfermedad valvular crónica de mitral es la enfermedad cardíaca más comúnmente reportada en perros de pequeño y mediano tamaño, adultos o ancianos. El síncope cardíaco es una manifestación comúnmente observada, causada por varios mecanismos. Esta investigación ha buscado relatar un caso de esta enfermedad en una perra de la raza Teckel, de 16 años de edad, que presentaba episodios recurrentes de síncope. Los episodios estaban asociados con bradicardia, palidez de mucosas y aumento de la presión intratorácica. Se ha excluido otras causas de síncope, se llevó a cabo el diagnóstico presuntivo de síncope neurocardiogénico, siendo la primera descripción en medicina veterinaria.
Subject(s)
Animals , Dogs , Heart Valve Diseases/diagnosis , Syncope, Vasovagal/diagnosisABSTRACT
Activation of 5-hydroxytryptamine (5-HT) 5-HT1A, 5-HT2C, 5-HT3, and 5-HT7 receptors modulates the excitability of cardiac vagal motoneurones, but the precise role of 5-HT2A/2B receptors in these phenomena is unclear. We report here the effects of intracisternal (ic) administration of selective 5-HT2A/2B antagonists on the vagal bradycardia elicited by activation of the von Bezold-Jarisch reflex with phenylbiguanide. The experiments were performed on urethane-anesthetized male Wistar rats (250-270 g, N = 7-9 per group). The animals were placed in a stereotaxic frame and their atlanto-occipital membrane was exposed to allow ic injections. The rats received atenolol (1 mg/kg, iv) to block the sympathetic component of the reflex bradycardia; 20-min later, the cardiopulmonary reflex was induced with phenylbiguanide (15 µg/kg, iv) injected at 15-min intervals until 3 similar bradycardias were obtained. Ten minutes after the last pre-drug bradycardia, R-96544 (a 5-HT2A antagonist; 0.1 µmol/kg), SB-204741 (a 5-HT2B antagonist; 0.1 µmol/kg) or vehicle was injected ic. The subsequent iv injections of phenylbiguanide were administered 5, 20, 35, and 50 min after the ic injection. The selective 5-HT2A receptor antagonism attenuated the vagal bradycardia and hypotension, with maximal effect at 35 min after the antagonist (pre-drug = -200 ± 11 bpm and -42 ± 3 mmHg; at 35 min = -84 ± 10 bpm and -33 ± 2 mmHg; P < 0.05). Neither the 5-HT2B receptor antagonists nor the vehicle changed the reflex. These data suggest that central 5-HT2A receptors modulate the central pathways of the parasympathetic component of the von Bezold-Jarisch reflex.
Subject(s)
Animals , Male , Rats , Bradycardia/physiopathology , /physiology , Reflex/drug effects , Vagus Nerve/drug effects , Analgesics/pharmacology , Atenolol/pharmacology , Biguanides/pharmacology , Bradycardia/chemically induced , Rats, Wistar , Reflex/radiation effects , Serotonin Receptor Agonists/pharmacology , Vagus Nerve/physiopathologyABSTRACT
Objective: To observe the influence of radiofrequency catheter ablation of the fat pad at the right pulmonary veinatria junction (RPV fat pad) on Bezold-Jarisch reflex (BJR) induced by veratridine in canine. Methods: Ten mongrel dogs were anesthetized and their chest were opened through a right thoracotomy to expose the RPV fat pad. Veratridine was injected into the left ventricle at bolus doses of 10 μg/kg through a catheter to induce BJR. The sinus cycle length (SCL), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), left ventricle systolic pressure (LVSP), left ventricle diastolic pressure (LVDP) and mean left ventricle pressure (MLVP) were measured under the baseline and after ablation of the RPV fat pad; the changes of the above parameters (ΔSCL, ΔSAP, ΔAP, ΔMAP, ΔLVSP, ΔLVDP, and ΔMLVP) were calculated. Then the same dose of veratridine was injected under the pad after ablation and the changes of the above parameters were observed. Results: BJR was successfully induced in the 8 animals; the animals has prolonged sinus cycle length (SCL) and decreased MAP and MLVP. After ablation, the prolongation of SCL after injection of veratridine was markedly reduced ([229.2±92.3] ms vs [39.3±14.1] ms,P<0.01). All the pressures were decreased after injection of veratridine, with significant decrease found only for DAP and MAP (both P<0.05). Conclusion: Ablation of the RPV fat pad can effectively attenuate the decrement of heart rate and the decrement of DAP and MAP during the BJR induced by veratridine, which provides a basis for the radiofrequency catheter ablation of vagus ganglions through endocardium.
ABSTRACT
Thoracoscopic thoracic sympathectomy (TTS) is usually a safe and uncomplicated procedure for treating essential palmar hyperhidrosis. However, we report a case of cardiovascular collapse that developed in a healthy patient undergoing TTS. The surgeon performed the left sympathectomy without incident. However, scarcely had an incision been made in the skin of the right chest when the patient developed sinus bradycardia and sudden, severe hypotension. Pulseless ventricular tachycardia occurred immediately thereafter, which rapidly progressed to ventricular fibrillation and cardiovascular collapse. The patient required resuscitation with 200 J of direct current shock defibrillation along with an intravenous injection of epinephrine 1 mg. She recovered without sequelae. We believe the Bezold-Jarisch reflex was triggered by pooling of venous blood and surgical stimuli, and the patient developed cardiovascular collapse as a result.
Subject(s)
Humans , Bradycardia , Epinephrine , Hyperhidrosis , Hypotension , Injections, Intravenous , Reflex , Resuscitation , Shock , Skin , Sympathectomy , Tachycardia, Ventricular , Thorax , Ventricular FibrillationABSTRACT
Vasovagal syncope is elicited by the Bezold-Jarisch reflex, triggered by anxiety, emotional stress or pain. It is the result of reflexively increasing parasympathetic tone and decreasing sympathetic tone sensed by chemoreceptor in vagus nerve and mechanoreceptor of ventricle, which causes bradycardia, systemic vasodilatation and profound hypotension. Although it is a transient episode in many cases, it could give rise to cardiac arrest. Diabetic autonomic neuropathy can lead to significant change in blood pressure and pulse rate, bradycardia, hypotension, and even cardiac arrest by increasing the risk of hemodynamic instability under general or regional anesthesia. We have experienced a patient who had once cardiac arrest following after positional change and recovered in a few minutes. The patient was supposed to have diabetic autonomic neuropathy under the emotional stress and anxiety before spinal anesthesia was done. We believe that this is the result of combination between paradoxical Bezold-Jarisch reflex caused by overactivation of parasympathetic nerve system and autonomic nervous system instability precipitated by diabetic autonomic neuropathy.
Subject(s)
Humans , Anesthesia, Conduction , Anesthesia, Spinal , Anxiety , Autonomic Nervous System , Blood Pressure , Bradycardia , Death, Sudden, Cardiac , Diabetic Neuropathies , Heart Arrest , Heart Rate , Hemodynamics , Hypotension , Mechanoreceptors , Reflex , Stress, Psychological , Syncope, Vasovagal , Vagus Nerve , VasodilationABSTRACT
Objective:To observe the influence of radiofrequency catheter ablation of the fat pad at the right pulmonary vein- atria junction(RPV fat pad)on Bezold-Jarisch reflex(BJR)induced by veratridine in canine.Methods:Ten mongrel dogs were anesthetized and their chest were opened through a right thoracotomy to expose the RPV fat pad.Veratridine was injected into the left ventricle at bolus doses of 10?g/kg through a catheter to induce BJR.The sinus cycle length(SCL),systolic arterial pressure(SAP),diastolic arterial pressure(DAP),mean arterial pressure(MAP),left ventricle systolic pressure(LVSP), left ventricle diastolic pressure(LVDP)and mean left ventricle pressure(MLVP)were measured under the baseline and after ablation of the RPV fat pad;the changes of the above parameters(?SCL,?SAP,?DAP,?MAP,?LVSP,?LVDP,and?MLVP)were calculated.Then the same dose of veratridine was injected under the pad after ablation and the changes of the a- bove parameters were observed.Results:BJR was successfully induced in the 8 animals;the animals has prolonged sinus cycle length(SCL)and decreased MAP and MLVP.After ablation,the prolongation of SCL after injection of veratridine was markedly reduced([229.2?92.3]ms vs[39.3?14.1]ms,P
ABSTRACT
PURPOSE--To evaluate the cardiogenic depressor Bezold-Jarisch reflex in rats with chronic myocardial infarction. METHODS--Adult Wistar rats were submitted to ligation of the anterior descending coronary artery of the left ventricle (group INF, n = 15) and compared with rats submitted to sham-operation (group Sham, n = 15). Thirty days after the surgery, without influence of anesthetics, the basal mean arterial pressure (MAP) and heart rate (HR) were measured. Immediately after, the Bezold-Jarisch reflex was evaluated measuring the falls in diastolic arterial pressure (DAP) and the simultaneous bradycardia induced by injections of 5-hydroxytryptamine (5-HT, 4 to 32 micrograms/kg, i.v.). RESULTS--The INF group showed significantly lower basal MAP and HR values (103 +/- 3 mmHg and 328 +/- 6 bpm) when compared to the Sham group (110 +/- 2 mmHg and 348 +/- 7 bpm). The Bezold-Jarisch reflex was significantly attenuated in the INF group (falls of DAP from 2 +/- 2 to 31 +/- 3 mmHg and HR from 8 +/- 5 to 204 +/- 15 bpm), when compared to the Sham group (falls of DAP from 10 +/- 3 to 41 +/- 3 mmHg and HR from 58 +/- 12 to 276 +/- 16 bpm). The morphological analysis showed a myocardial infarction mainly located at the anterolateral portion of the left ventricle with a maximal extension of 35 of the left ventricle circumference. The INF group showed right ventricular and left atrial hypertrophy when compared to the Sham group. CONCLUSION--The experimental chronic myocardial infarction in rats is followed by significant attenuation of the Bezold-Jarisch reflex, probably as result of a heart failure and, consequently, of functional alterations in the chemosensitive receptors of cardiac unmyelinated vagal afferents.