The human heart rate response profiles to five vagal maneuvers

Healthy teens and adults performed four vagotonic maneuvers. A large series of strabismus surgery patients had deliberately quantified tension on extraocular rectus muscles during general anesthesia. The mean bradycardia was greatest for diving response (apneic facial exposure to cold) and Valsalva maneuver and least for pressure on the globe and carotid sinus massage. Bradycardia occurred for every subject for the non-surgical maneuvers, however, extraocular muscle tension frequently caused no change in heart rate or even tachycardia. The inter-subject variance in percent heart rate change was greatest for surgical oculocardiac reflex. Of the rectus muscles, the inferior caused the most bradycardia while the lateral caused the least. The percent oculocardiac reflex was not age dependent. Occasional patients demonstrated profound bradycardia with strabismus surgery. Of these maneuvers, diving response has theoretical advantage in treating paroxysmal atrial tachycardia. The human cardiac vagal efferent was stimulated by several carefully controlled maneuvers resulting in wide inter-maneuver differences in bradycardia magnitude. The greatest intra-maneuver variability occurred with surgical oculocardiac reflex.     

Elicitation of the oculocardiac reflex during endoscopic forehead lift surgery.

Elicitation of the oculocardiac reflex is a well-documented phenomenon encountered during ophthalmologic surgical procedures. Familiarity with and prompt recognition of this entity has significantly reduced the morbidity associated with it; however, potentially lethal arrhythmias and cardiac arrest still occur. We report elicitation of the reflex during manipulation of the supraorbital nerve during endoscopic forehead lift surgery. To our knowledge this is the first case of elicitation of the oculocardiac reflex reported during endoscopic forehead lift surgery.     

Retro-orbicularis oculus fat (ROOF) resection in aesthetic blepharoplasty: a 6-year study in 63 patients

Sixty-three nonconsecutive patients have undergone resection of the retro-orbicularis oculus fat (ROOF) in conjunction with aesthetic blepharoplasty. In these patients, a consistent and useful ability to soften and flatten heaviness and bulkiness in the lateral upper orbital region was seen. Two patients developed postoperative hematoma, and two different patients had transient dry-eye symptoms following blepharoplasty. Twenty percent of patients had a transient degree of numbness in the lateral supraorbital nerve region, and all patients noted some transient numbness over the lateral upper brow region. No patient demonstrated significant paralysis of the orbicularis oculus or corrugator muscle. From this experience, retro-orbicularis oculus fat resection would appear to be a useful adjunct to standard blepharoplasty techniques in selected patients.     

Maxillomandibulocardiac reflex in a dog

Background

The trigeminocardiac reflex (TCR) is a brainstem reflex that may be observed in anaesthesia during surgical procedures stimulating the intracranial or peripheral portion of the trigeminal nerve. The peripheral TCR is divided into the oculocardiac reflex and the maxillomandibulocardiac reflex based on the affected sensory branches of the trigeminal nerve. In veterinary medicine the oculocardiac reflex has been described, however the maxillomandibulocardiac reflex has never been reported.

Case presentation

A 5-year-old male Epagneul Breton was presented for surgical management of an upper lip mass. During surgery, a sudden severe bradycardia and a decrease in systemic arterial blood pressure developed. The occurrence of a maxillomandibulocardiac reflex was suspected on the basis of the temporary link between surgical stimulation and haemodynamic changes. Three doses of atropine were given before starting a dopamine infusion due to lack of response. The dopamine infusion normalized heart rhythm and blood pressure. The dog recovered uneventfully and he was discharged 24 h later with a sinus rhythm and no sign of recurrence of arrhythmias.

Conclusion

The TCR is a rare but potentially life-threatening complication of procedures involving the sensory areas innervated by the three branches of the trigeminal nerve and it may cause bradycardia with hypotension. The use of a β1-adrenergic receptor agonist such as dopamine may be indicated in cases of a refractory response to the conventional treatment with atropine.

     

Expanded applications for transconjunctival lower lid blepharoplasty.

There has been a recent upsurge in interest in the transconjunctival approach for lower lid blepharoplasty. Initial reports have focused on the young patient with isolated fat prominence. We describe our experience with transconjunctival lower lid blepharoplasty in 104 patients over the past 2 years. There have been no instances of prolonged lower lid retraction problems, presumably related to leaving the skin, orbicularis, and orbital septum intact. Our experience with expanding the indications for the transconjunctival approach to include patients with fine skin wrinkling as well as frank skin excess has been extremely favorable. We conclude that the skin excess is often more apparent than real, with the skin being necessary to recontour the lower eyelid after fat excision. Although skin excision may be required during the initial procedure or at a later stage, patients with apparent skin excess need not be excluded from consideration for transconjunctival lower lid blepharoplasty.     

Adipose compartments of the upper eyelid: anatomy applied to blepharoplasty

Many authors have indicated the presence of ectopic or accessory upper eyelid fat pads, but the effective rate of eyelid fat variations and the corresponding clinical features are still unclear. The purpose of this study was to evaluate the variability of upper lid fat and to define the anatomical landmarks of the adipose pockets of the upper lid. From January of 1998 to January of 2002, the authors investigated the upper eyelid fat compartments of 47 patients who underwent upper blepharoplasty. To support surgical findings, 11 fresh cadavers were also investigated; the anatomy of the intraorbital fat and of the upper eyelid fat compartments was reviewed. Ten patients (21.3 percent) showed an accessory fat pad in the upper lid, which was found on both sides in nine cases. In all patients, the third fat pad was situated lateral to the two classic compartments described by Castanares, behind the orbital septum. Surgical dissections demonstrated that this fat pad derived from the preaponeurotic fat. Anatomical dissections in three cadavers demonstrated an accessory fat compartment protruding under the inferior border of the lacrimal gland. This protruding fat derived from the preaponeurotic fat in all cases and might justify the clinical appearance of a bulge or fullness in the lateral third of the upper eyelid. In the authors' experience, the presence of an accessory upper eyelid fat pad was a frequent finding during blepharoplasty; it could be found and actually resected in about 21 percent of all cases. Surgical and experimental findings put this element as a lateral physiological extension of the preaponeurotic fat that can anteriorly protrude under the inferior border of the lacrimal gland toward the orbital septum. The clinical appearance may be a bulge or fullness in the upper eyelid, and its resection can better define the lateral one third of the supratarsal fold.     

Strategies for a successful corrective Asian blepharoplasty after previously failed revisions

Asian blepharoplasty, although a common procedure, has a relatively high rate of complications. Subtle imperfections and more serious iatrogenic complications often require immediate attention by the aesthetic surgeon. After attempted correction of the deformities, residual problems or new ones can arise. Blepharoptosis, supratarsal depression, an excessively high or low crease, a short or discontinuous crease, multiple creases, and asymmetric creases are the most commonly encountered complications that require special attention in this group, which has already undergone more than one surgical procedure. Between January of 1996 and December of 2002, 168 Asian blepharoplasty revisions were performed by one surgeon (S. H.-T. Chen); of these, 36 patients (21 percent) had previously undergone failed revisions. This subgroup of patients consisted of six with blepharoptosis, six with asymmetrical eyelid creases, three with supratarsal depressions, three with high creases, two with short creases, and 16 with combinations of these deformities. The results were graded as excellent, good, fair, or poor, based on the symmetry of the eyelids, palpebral fissures, crease heights, lengths, shapes, eyelid fullness, and overall aesthetics of the final outcome. A survey was performed of patient and surgeon satisfaction and factored into the grading system. With an average follow-up period of 16 months (6 to 60 months), 22 patients (61 percent) were found to have excellent results, 10 (28 percent) had good results, two (5.6 percent) had fair results, and two (5.6 percent) had poor results. Corrective procedures after failed revision Asian blepharoplasty require special strategic considerations because of the presence of extensive scarring and inadequate skin, muscle, and preaponeurotic fat and because of the occasional presence of dehiscence of the levator aponeurosis. By using careful preoperative evaluation, accurate measurements, precise preoperative planning, intraoperative fat repositioning or grafting, skin excision or redraping, and proper placement of anchoring sutures, successful outcomes can be achieved. The authors evaluate the outcomes and detail the surgical procedures that were used to achieve successful outcomes in this particularly challenging group of patients.     

Effect of systemic B-type natriuretic peptide on cardiac vagal motoneuron activity

Intravenous B-type natriuretic peptide (BNP) enhances the bradycardia of reflexes from the heart, including the von Bezold-Jarisch reflex, but its site of action is unknown. The peptide is unlikely to penetrate the blood-brain barrier but could act on afferent or efferent reflex pathways. To investigate the latter, two types of experiment were performed on urethane-anesthetized (1.4 g/kg iv) rats. First, the activity was recorded extracellularly from single cardiac vagal motoneurons (CVMs) in the nucleus ambiguus. CVMs were identified by antidromic activation from the cardiac vagal branch and by their barosensitivity. Phenyl biguanide (PBG), injected via the right atrium in bolus doses of 1-5 mug to evoke the von Bezold-Jarisch reflex, caused a dose-related increase in CVM activity and bradycardia. BNP infusion (25 pmol.kg(-1).min(-1) iv) significantly enhanced both the CVM response to PBG (n = 5 rats) and the reflex bradycardia, but the log-linear relation between those two responses over a range of PBG doses was unchanged by BNP. The reflex bradycardia was not enhanced in five matched time-control rats receiving only vehicle infusions. In five other rats the cervical vagi were cut and the peripheral right vagus was stimulated supramaximally at frequencies of 1-20 Hz. The bradycardic responses to these stimuli were unchanged before, during, and after BNP infusion. We conclude that systemic BNP in a moderate dose enhances the von Bezold-Jarisch reflex activation of CVM, in parallel with the enhanced reflex bradycardia. That enhancement is due entirely to an action before the vagal efferent arm of the reflex pathway.     

Thermal bradycardia during radiofrequency irradiation

The present study was performed to determine if any heart rate or blood pressure changes occur during intermittent exposure to radiofrequency radiation (RFR), and to determine if parasympathetic blockade due to atropine has any effect on these changes or on thermal responses. Anesthetized rats were exposed to 2.8 GHz pulsed RFR at an average power level of 60 mW/cm2 (average specific absorption rate, 14 W/kg). During an initial exposure period to raise colonic temperature to 39.5 degrees C, heart rate decreased significantly. This thermal bradycardia is similar to that reported by other investigators during environmental heat exposure. Intermittent exposure to radiation, which was designed to result in 1 degree C colonic temperature changes, did not significantly affect heart rate or mean arterial blood pressure, before or after atropine administration. The time courses of these 1 degree C temperature changes were not altered significantly by atropine. Following administration of atropine, the thermal bradycardia during the initial heating period was still evident. Thus, factors other than vagal activity are responsible for the phenomenon. It is possible that the bradycardia is a consequence of a general reduction in metabolism, which occurs also during environmental heat exposure.     

Intraoperative injection of botulinum toxin A into orbicularis oculi muscle for the treatment of crow's feet

The purpose of this investigation was to evaluate the degree of efficacy of eliminating crow's feet by means of direct injection of botulinum toxin A into orbicularis oculi muscles under direct surgical vision during either blepharoplasty or face lift operations. Eighteen patients were injected with Botox A-14 in each orbicularis oculi muscle. Dilution was obtained by adding 4 ml of preservative-free saline to 100 IU of Botox A. Doses ranged from 15 to 50 IU in each muscle, varying according to the severity of wrinkles and intensity of muscle contraction. In 10 patients (56 percent), the Botox was injected throughout the outer surface of both orbicularis oculi dissected during a face-lift operation. In eight other patients (44 percent), the toxin was injected into the inner surface of both orbicularis oculi exposed during classic blepharoplasty procedures. Most authors have demonstrated that the effect produced by transcutaneous Botox lasts between 4 and 6 months; the paralysis obtained by direct muscular injection was effective for 9 months in 14 patients (78 percent) and 10 months in the other 4 patients (22 percent). Results were documented by means of preinjection and postinjection photographs, videotapes, and electromyographs. Neither local nor general adverse effects were noted. The improvement obtained in crow's feet was satisfactory to the patient and to us. The use of Botox intraoperatively permitted at the same time not only the treatment of crow's feet by paralysis of orbicularis oculi muscles but also the correction of senile changes in the lids and face by means of either blepharoplasty or face-lift operations.     

Retrobulbar hematoma and blepharoplasty

Retrobulbar hematoma leading to visual impairment is a rare but serious complication associated with elective blepharoplasty. A review of the literature addressing etiology, prevention, and management is presented. Removal of anterior orbital fat associated with traction and rupture of vessels within posterior orbital fat is currently most strongly supported as the cause of retrobulbar hematoma after blepharoplasty. Optic nerve ischemia is identified as the likely cause of visual impairment. Specific recommendations for avoidance and management of acute retrobulbar hematoma are offered. Recent background animal and human research is summarized.     

Cardiac Arrest during Gamete Release in Chum Salmon Regulated by the Parasympathetic Nerve System

Cardiac arrest caused by startling stimuli, such as visual and vibration stimuli, has been reported in some animals and could be considered as an extraordinary case of bradycardia and defined as reversible missed heart beats. Variability of the heart rate is established as a balance between an autonomic system, namely cholinergic vagus inhibition, and excitatory adrenergic stimulation of neural and hormonal action in teleost. However, the cardiac arrest and its regulating nervous mechanism remain poorly understood. We show, by using electrocardiogram (ECG) data loggers, that cardiac arrest occurs in chum salmon (Oncorhynchus keta) at the moment of gamete release for 7.39±1.61 s in females and for 5.20±0.97 s in males. The increase in heart rate during spawning behavior relative to the background rate during the resting period suggests that cardiac arrest is a characteristic physiological phenomenon of the extraordinarily high heart rate during spawning behavior. The ECG morphological analysis showed a peaked and tall T-wave adjacent to the cardiac arrest, indicating an increase in potassium permeability in cardiac muscle cells, which would function to retard the cardiac action potential. Pharmacological studies showed that the cardiac arrest was abolished by injection of atropine, a muscarinic receptor antagonist, revealing that the cardiac arrest is a reflex response of the parasympathetic nerve system, although injection of sotalol, a β-adrenergic antagonist, did not affect the cardiac arrest. We conclude that cardiac arrest during gamete release in spawning release in spawning chum salmon is a physiological reflex response controlled by the parasympathetic nervous system. This cardiac arrest represents a response to the gaping behavior that occurs at the moment of gamete release.     

Modulation of cardiopulmonary depressor reflex in nucleus ambiguus by electroacupuncture: roles of opioids and γ-aminobutyric acid

Stimulation of cardiopulmonary receptors with phenylbiguanide (PBG) elicits depressor cardiovascular reflex responses, including decreases in blood pressure and heart rate mediated in part by the brain stem parasympathetic cardiac neurons in the nucleus ambiguus (NAmb). The present study examined NAmb neurotransmitter mechanisms underlying the influence of electroacupuncture (EA) on the PBG-induced hypotension and bradycardia. We hypothesized that somatic stimulation during EA modulates PBG responses through opioid and γ-aminobutyric acid (GABA) modulation in the NAmb. Anesthetized and ventilated cats were studied during repeated stimulation with PBG or cardiac vagal afferents while low-frequency EA (2 Hz) was applied at P5-6 acupoints overlying the median nerve for 30 min and NAmb neuronal activity, heart rate, and blood pressure were recorded. Microinjection of kainic acid into the NAmb attenuated the PBG-induced bradycardia from -60 ± 11 to -36 ± 11 beats/min. Likewise, EA reduced the PBG-induced depressor and bradycardia reflex by 52 and 61%, respectively. Cardiac vagal afferent evoked preganglionic cellular activity in the NAmb was reduced by EA for about 60 min. Blockade of opioid or GABA(A) receptors using naloxone and gabazine reversed the EA-related modulation of the evoked cardiac vagal activity by 73 and 53%, respectively. Similarly, naloxone and gabazine reversed EA modulation of the negative chronotropic responses from -11 ± 5 to -23 ± 6 and -13 ± 4 to -24 ± 3 beats/min, respectively. Thus EA at P5-6 decreases PBG evoked hypotension and bradycardia as well as the NAmb PBG-sensitive preganglionic cardiac vagal outflow through opioid and GABA neurotransmitter systems.     

Verapamil Reverses Myocardial No-Reflow After Primary Percutaneous Coronary Intervention in Patients with Acute Myocardial Infarction

The present study evaluated the efficacy of intracoronary administration of verapamil to attenuate the no-reflow phenomenon following the primary percutaneous coronary intervention (PCI) in patients with the ST-segment elevation acute myocardial infarction (STEMI). A total of 201 patients with STEMI who underwent primary PCI within 12 h from the beginning of the heart attack were included. The no-reflow phenomenon was defined as substantial coronary anterograde flow of TIMI ≤2. Verapamil (100–200 μg) was injected into coronary artery immediately after no-reflow; the coronary arteriography was repeated later. Hundred and ninety-eight patients with STEMI successfully underwent primary PCI, and 246 stents were implanted with the average of 1.2 stents per patient. No-reflow occurred in 25 out of 198 patients (12.6 %). Twenty-one (84 %) patients developed the flow of TIMI ≥3 after intracoronary administration of verapamil, as revealed by repeated coronary angiography. Two patients developed transient hypotension which normalized without treatment within 3–5 min. Three patients showed sinus bradycardia, in one patient there was transient II sinoatrial block, and one patient developed type 1 atrioventricular block. All adverse effects were alleviated after intravenous injection of atropine (0.5–1 mg). In conclusion, the no-reflow phenomenon following primary PCI in patients with STEMI is significantly improved by intracoronary administration of verapamil which is useful to reduce cardiovascular events during operation.     

Two helpful technical aids in blepharoplasty

We describe two helpful technical aids in blepharoplasty. The first is a method of securely holding orbital fat without risk of excessive traction if the patient's head moves. The second involves use of a battery-powered cautery as a safe, convenient cutting instrument.     

Reflex cardiorespiratory responses to pulmonary vascular congestion

The purpose of these studies was to determine the reflex responses of the cardiovascular system and central inspiratory activity caused by pulmonary vascular congestion. We used a canine preparation in which the left lung was isolated in situ and could be exposed to a variety of stimuli, including distension of the pulmonary capillaries with blood, without direct mechanical or chemical alterations on the circulation. We found that lung expansion to 30 cmH2O and stimulation of nerve endings of the left lung with capsaicin caused pronounced transient reflex bradycardia (-30 to -50 beats/min) and hypotension (-25 to -40 mmHg) and caused reflex cessation of inspiratory activity. Pressurizing the left pulmonary vessels by injecting blood in volumes sufficient to raise pulmonary transcapillary pressures to 30 mmHg caused no changes in heart rate, systemic arterial pressure, or inspiratory muscle activity. These results lead us to conclude that pulmonary vascular congestion does not stimulate pulmonary C-fibers or any other nerve endings to such a degree as to cause detectable changes in blood pressure, heart rate, or central inspiratory activity. Morphometric analysis revealed distended capillaries engorged with blood, but the alveolar wall surface area was not increased which raises the possibility that expansion of the alveolar membrane may be needed to mechanically initiate the C-fiber reflex.     

Use of immunohistochemical stains to assess the variations in color of fat of the upper eyelid

Although there are many variations on the technique, most practitioners agree that removal of periorbital eyelid fat is an integral part of the blepharoplasty operation. The retrieval and excision of the medial fat of the upper eyelid is a step that, when overlooked, leaves the patient with an unsatisfactory appearance of puffiness in this area. The medial fat is characteristically white; the other fat compartments are yellow. The authors attempt to understand why these two juxtaposed fat pockets are of distinct different colors. Four consecutive patients underwent traditional upper blepharoplasty surgery. From each patient two separate fat specimens were identified as upper lateral and upper medial. These fat specimens were processed with hematoxylin and eosin and various immunohistochemical stains. A board-certified pathologist, who was blinded as to the anatomic site of the fat, evaluated them. The medial fat showed much larger fat lobules than the upper lateral fat. Contrasting this, the lateral fat had many more endothelial-lined blood vessels and much thicker fibrous septa than its medial neighbor. These findings were supported immunohistochemically by using CD34 (endothelial antibody) and factor XIIIa (dermal dendritic cell/ normal fibroblast antibody). The use of other immunostains using various antibodies did not distinguish any distinct histomorphology among the specimens. Although for the operating surgeon it is important to recognize the white color of the medial fat to aid in identification during surgery, one can only speculate as to what contributes to this difference in blood vessels and supporting fibrous septa. Most likely this is the result of anatomic, embryologic, and vascular bed differences.     

Adrenergic responses of the cardiovascular system of the eel, Anguilla australis, in vivo

Heart output, arterial pressures, and heart rate were measured directly in conscious unrestrained eels (Anguilla australis) and responses to intra-arterial injection of adrenaline monitored. Adrenaline increased systemic vascular resistance, heart output, and cardiac stroke volume in all animals. In some cases small transient decreases in stroke volume and hence heart output were seen at the peak of the pressor response: These probably reflect a passive decrease in systolic emptying due to increased afterload on the heart. In most cases, adrenaline produced tachycardia; but two animals showed consistent and profound reflex bradycardia, which was accompanied by a concomitant increase in stroke volume such that heart output was maintained or increased slightly. The interaction of changes in heart output and systemic vascular resistance produced complex and variable changes in arterial pressure. There was no consistent pattern of changes in branchial vascular resistance. Atropine treatment in vivo revealed vagal cardio-inhibitory tone in some animals and always blocked the reflex bradycardia seen during adrenaline induced hypertension. In some animals, adrenaline injection after atropine pretreatment led to the establishment of cyclic changes in arterial pressure with a period of about 1 min (Mayer waves).     

Lower eyelid blepharoplasty: analysis of indications and the treatment of 100 patients

Traditionally, lower lid blepharoplasty has been confined to a choice of skin or skin-muscle flap transcutaneous blepharoplasty. In the past decade, in particular, various new techniques and technologies have emerged, altering our ability to treat the lower eyelids. These techniques include transconjunctival blepharoplasty, a variety of canthopexy procedures, fat-conserving or fat-replacing methods, wedge excision, and laser resurfacing techniques, and they allow a more individualized approach based on variations in anatomical features and patient goals. A retrospective review of data for 100 consecutive patients (ranging in age from 30 to 80 years) who underwent lower eyelid procedures during a 12-month period is presented. Procedures were categorized as follows: lower lid blepharoplasty, 35 cases; lower lid transconjunctival blepharoplasty, 27 cases; lower lid transconjunctival blepharoplasty with laser resurfacing, 17 cases; lower lid laser resurfacing, 16 cases; tarsorrhaphy with lower lid operation, three cases; tarsorrhaphy with laser resurfacing, two cases. Two complications of retained fat pads (one medial and one lateral) were encountered and were addressed with a secondary operation using a transconjunctival blepharoplasty approach. The results indicate that laser treatment has become the predominant form of lower eyelid resurfacing and that transconjunctival blepharoplasty is now the most common surgical procedure for the lower eyelid. All of our tarsorrhaphy procedures were performed for patients who had previously undergone surgical treatment of the lower eyelids. An algorithm based on physical findings and these techniques has been developed, for appropriate tailoring of the procedure to each patient's specific concerns. With the availability of a variety of techniques, an individualized approach based on variations in anatomical features is feasible.     

Bioelectrical analysis of the regulatory interaction of sympathetic and parasympathetic nervous influences on the heart rhythm]

The changes of chronotropic effect on the isolated sinus node of the frog heart were studied during the separate and simultaneous stimulation of the sympathetic and intracardiac reflex parasympathetic pathways. Intracellular activity of the pacemaker cells was recorded. The separate stimulation of the intracardiac reflex system resulted in bradycardia (in winter) or tachycardia (in summer). Stimulation of sympathetic chain supervening the activation of the intracardiac pathways induced an intensification of both the parasympathetic bradycardia and tachycardia; these effects were cholinergic in nature. The recording of the intracellular pacemaker activity showed the existence of the complicated interaction between the sympathetic and parasympathetic pulse-mediator actions on the heart pacemaker both on the prepulase process and on the membrane polarization and other action potential parameters. Possible mechanisms of this interaction are discussed.