Safety of nerve conduction studies in patients with peripheral intravenous lines

Nerve conduction studies (NCS) may be deferred because of a perceived risk of cardiac arrhythmia in the presence of same‐limb peripheral intravenous lines. Patients with implanted pacemakers or defibrillators provide a model in whom this risk can be assessed. Twenty patients, seven with pacemakers and 13 with defibrillators, had peripheral intravenous lines placed during routine care and underwent NCS in the same limb. NCS were performed with the intravenous line clamped and then with saline open to gravity. The implanted cardiac device was interrogated before and after the study. During NCS the surface electrocardiogram and intracardiac electrograms were monitored continuously. Electrical impulses generated during routine NCS were never detected by the sensing amplifiers of the pacemakers/defibrillators and did not affect the programmed settings or interfere with pacing of the device. Routine NCS are safe in patients with same‐limb peripheral intravenous lines, even with saline open to gravity. Muscle Nerve 42:189–191, 2010     

The role of cardiac pacing in carotid sinus syndrome: a meta-analysis

Purpose

Cardiac pacing can be used to treat carotid sinus syndrome (CSS), but clinical studies have shown conflicting results. We conducted a systematic review and meta-analysis to evaluate the role of pacing for CSS.

Methods

A systematic search of publications in PubMed, Embase, and the Cochrane Library without language restriction was performed. Prospective randomized studies that compared cardiac pacing with standard therapy or pacing with different algorithms were included if the recurrence of syncope or the number of falls was observed.

Results

Eight studies enrolling 540 patients were identified. In open-label studies, the recurrence of syncope was reduced significantly by cardiac pacing compared with standard therapy. The recurrence of syncope was not different between single- and dual-chamber pacing, but a lower rate of patients with pre-syncope was observed in the group with dual-chamber pacing. Double-blind clinical studies failed to observe the role of cardiac pacing for preventing falls in patients with CSS.

Conclusion

The results of meta-analysis supported the use of cardiac pacing for patients with dominant cardioinhibitory CSS.     

Pacemakers, cardiac mapping and EEG in the community hospital: a concise review of background and basic technical considerations.

The heart is a pump. The objective of cardiac pacing is to improve the cardiac output. The most popular method of cardiac pacing (RV) is not physiologic and results in reduced stroke output when compared to that of normal sinus or atrial paced rhythm. Recognition of pacemaker induced low output states and pacemaker aggravated neurological symptoms has quickened interest in physiologic atrial pacing. The increased complexity of atrial pacing has been discouraging in the past, but technical advances in electrode and pacemaker design are promising. Selection of the optimal pacing site appears critical and requires the determination of the focal electrical potential and stimulating threshold before electrodes are positioned. With minimal expense, the EEG can be adapted for this type of cardiac mapping in the community hospital.     

The treatment of ictal asystole with cardiac pacing

Ictal asystole may contribute to seizure-related injury and mortality. The purpose of this study was to evaluate the effect of cardiac pacing on seizure-related injury rates in ictal asystole patients. A survey was conducted to determine seizure-related fall rate and other morbidity in all seven patients with ictal asystole who underwent cardiac pacing at our institution between 1990 and 2004. The rate of seizure-related falls and other morbidities before and after pacing were compared using the Wilcoxon rank-sum test. The mean fall rate was 3.28 falls/month pre-pacemaker implantation. Following pacemaker implantation, this was reduced to 0.005 falls/month (p = 0.001). Seizure-related fractures and motor vehicle accidents were also reduced following cardiac pacing. These findings may have implications in mitigating the potential morbidity associated with ictal asystole.     

Outpatient continuous inotrope infusion as an adjunct to heart failure therapy in Duchenne muscular dystrophy

We report the use of continuous intravenous inotrope infusion as a palliative management strategy for the treatment of symptomatic, refractory, end stage cardiac dysfunction in patients with Duchenne muscular dystrophy. Milrinone and/or dobutamine administered by continuous intravenous infusion provided symptomatic and objective cardiovascular improvement up to 30 months in 3 individuals with Duchenne muscular dystrophy and severe dilated cardiomyopathy. Continuous inotrope infusion should be considered a practical treatment strategy for end stage cardiac dysfunction in Duchenne muscular dystrophy patients when cardiac transplantation is not a viable option.     

Ictal asystole in epilepsy patients undergoing inpatient video-EEG monitoring

Ictal asystole (IA) is uncommonly diagnosed and has been implicated as a potential cause of sudden unexpected death in epilepsy. Sudden unexpected death in epilepsy is an increasingly recognizable condition and is more likely to occur in patients with medically intractable epilepsy and those suffering from convulsive epilepsy. We report 2 cases of recent onset of prolonged syncope and unrevealing cardiac work up. The inpatient video-EEG monitoring recorded left temporal ictal discharges followed by IA. Although the role of cardiac pacing is controversial in these patients, both patients had favorable outcome following cardiac pacemaker insertion. This report demonstrates the variability in IA pathophysiology and clinical manifestations. It also advocates that cardiac pacing might have a role in the management of IA.Ictal asystole (IA) is an uncommon event that occurs in 0.1-0.4% of patients experiencing seizures during inpatient video-electroencephalography monitoring (VEEG).1 Ictal asystole is more likely to occur in patients with focal seizures originating from the temporal region.2 It has been implicated as a potential cause for sudden unexpected death in epilepsy patients (SUDEP) that carry an incidence of 0.09-9.3 per 1000 patient-years.1 Although controversial, cardiac pacing has been suggested as a possible preventive measure against IA and SUDEP.3 We report 2 cases of IA encountered at our epilepsy monitoring unit between June 2010 and October 2011, and their clinical outcomes after cardiac pacemaker insertions. These 2 cases highlight the importance in considering IA as a potentially fatal complication of epileptic seizures that might be circumvented by good seizure control, and in some cases cardiac pacing.     

Cardiac pacing does not improve orthostatic tolerance in patients with vasovagal syncope

This study was undertaken to assess the value of dual chamber pacing in the treatment of vasovagal syncope. In a preliminary study, on two patients the time to presyncope during head-up tilt before and after implanting pacemakers was determined. Both patients fainted with similar decreases in blood pressure at almost exactly the same time after tilting. In the main study, nine patients with pacemakers implanted as treatment for syncope were studied, in random order, with pacemakers on and either off or turned to minimum rate. The pacemakers prevented bradycardia but had no effect on the time to syncope in a progressive test of head-up tilt followed by the addition of graded lower body suction. It is concluded that cardiac pacing does not prevent or even delay the onset of postural syncope and infer that bradycardia is an unimportant component of vasovagal attacks.     

Vasovagal syncope with asystole: the role of cardiac pacing

Clinical Autonomic Research - Whereas cardiac pacing has a very limited role overall in patients with vasovagal syncope (VVS), there are three reasons which support pacing efficacy in tilt-induced...     

Vagal action on atrioventricular conduction and its inhibition by sympathetic stimulation and neuropeptide Y in anaesthetised dogs

The observed change in atrioventricular conduction time (PR interval) in response to vagal stimulation is the result of two opposing effects; PR interval increases in response to the direct action of the vagus on atrioventricular nodal cells (direct effect), and the accompanying slowing of heart rate acts to decrease PR interval (indirect effect). The relationships between these opposing effects were studied in anaesthetised dogs. This study has shown that the increase in PR interval in response to vagal stimulation is well correlated with vagal stimulation frequency and can be regarded as linear. This is so for unpaced and paced hearts. We have also shown there is an increase in the sensitivity of the relationship between increase in PR interval and vagal stimulation frequency during pacing. This increase in sensitivity is attributable to the elimination of the indirect effect of the slowing of heart rate. During atrial pacing, the relationship between pulse interval and PR interval resembles a hyperbola. At low-pulse intervals (i.e. fast heart rates) the PR interval increases. This is in agreement with previous qualitative findings and is related to the functional refractory period of the atrioventricular cells. The action of sympathetic stimulation and injection of neuropeptide Y has not been studied previously. The vagally induced increase in atrioventricular conduction time is attenuated for many minutes following stimulation of the cardiac sympathetic nerve at 16 Hz for 2 min or by intravenous injection of neuropeptide Y (25-50 micrograms/kg). Stimulation of the right cardiac sympathetic nerve evokes a significantly stronger inhibition of the vagally induced prolongation of pulse interval than stimulation of the left sympathetic nerve. On the other hand, stimulation of the left or right sympathetic nerves cause similar inhibition of vagal action on atrioventricular conduction time.     

Pacing does not improve hypotension in patients with severe orthostatic hypotension

Abstract. Background Tachypacing has been suggested to compensate for drop in blood pressure as a technique to improve symptoms in patients with severe orthostatic hypotension secondary to autonomic dysfunction. To date, however, no randomized controlled studies have been performed to validate the approach. Methods and results Six patients with severe orthostatic hypotension and chronotropic incompetence secondary to autonomic dysfunction underwent a prospective randomized cross–over tilt table study with no pacing and with temporary DDD pacing at 90 and 110 bpm. Time to syncope or pre–syncopal symptoms, blood pressure changes, stroke volume and cardiac output were recorded using real time hemodynamic monitoring and echocardiography. All patients, except for one, had a drop in blood pressure and syncope or pre–syncopal symptoms during tilt regardless of whether they were paced or not. There was also no difference in any of the measured hemodynamic and vasomotor parameters with pacing. Conclusions Pacing did not produce any benefits in terms of symptoms or in any of the measured hemodynamic variables during tilt for patients with severe orthostatic hypotension secondary to autonomic dysfunction in this limited pilot study.     

Use of demand pacemaker in children with Guillain-Barré syndrome and cardiac arrhythmias

We report 2 patients with Guillain-Barré syndrome who exhibited autonomic dysfunction, including lability of blood pressure and heart rate, frequent episodes of profound bradycardia, and occasional asystole. Both patients required insertion of a temporary venous pacemaker which was activated a few times during the following days. The potential need for ventilatory support in patients with Guillain-Barré syndrome is well known; however, death in these patients due to acute cardiovascular failure during autonomic dysfunction continues to occur. The patients' courses emphasize the significance of cardiac monitoring and the potential use of cardiac pacing in Guillain-Barré syndrome patients who exhibit autonomic dysfunction.     

Cardiac arrhythmias in Guillain-Barre syndrome. An overview of the diagnosis of a rare but potentially life-threatening complication

Autonomic neuropathy is an important complication of Guillain-Barré syndrome (GBS). In particular, over-reactivity of vagal function may lead to serious cardiac disturbances ranging from bradycardia to asystole. Early recognition of these events is essential for appropriate intervention such as the insertion of a cardiac pacemaker. Recent studies indicate that serious bradyarrhythmias could be observed in severely and even less severely affected patients who were still able to walk more than 5 meters. Conventional measures such as the presence of tachycardia, heart rate and blood pressure fluctuations, or short-term heart rate variability and standardized autonomic function tests were not useful in predicting serious bradyarrhythmias. However, abnormal sensitivity to eyeball pressure testing correctly identified two of three patients who needed cardiac pacing or cardiopulmonary resuscitation due to heart arrest; eight of ten patients without bradyarrhythmic events showed normal responses. New methods such as the 24-hour heart rate power spectrum may yield sensitive and specific markers for assessing the risk of impending and potentially life-threatening arrhythmias in patients with GBS.     

Ischemic stroke after cardiac pacemaker implantation in sick sinus syndrome

The risk of embolic stroke during sick sinus syndrome before cardiac pacemaker insertion is substantial, but stroke after pacemaker insertion has not been well studied. We observed 10 sick sinus syndrome patients who developed an ischemic stroke 4 days to 112 months after pacemaker insertion. Nine patients represented 6% of the 156 ischemic stroke patients observed during a 30-month period. Eight had a ventricular-demand pacemaker, one had a dual-chamber pacemaker, and one had an atrial-inhibited pacemaker. Six patients were in atrial fibrillation at stroke onset, but none had atrial fibrillation when the pacemaker was inserted. Six patients were taking aspirin, and one was anticoagulated when stroke occurred. Stroke in sick sinus syndrome after pacemaker insertion is not rare, and pacing does not appear to be protective. Sick sinus syndrome patients who convert to atrial fibrillation or who have a ventricular-demand pacemaker might represent high-risk groups for stroke.     

Atropine in Electroconvulsive Therapy

Nineteen patients with major depression were alternately given intravenous atropine or saline immediately prior to anesthesia for electroconvulsive therapy (ECT). Atropine increased the heart rate, reduced the number of dropped beats, and reduced the number of premature atrial beats. These features may be advantageous in patients with cardiac hypodynamic states presenting for ECT, that is, with bradycardia, bradyarrhythmia, or hypotension. However, as atropine also increased the cardiac work, we recommend that it not be given to patients with hypertension, tachycardia, or who are at risk for cardiac ischemia.     

Syncope associated with pain as the presenting feature of neck malignancy: failure of cardiac pacemaker to prevent attacks in two cases

Two patients are described in whom syncope was the presenting clinical feature of an undiagnosed neck malignancy. Both patients also had attacks associated with paroxysms of severe neck pain. Neither patient responded to cardiac pacing.     

High cardiovascular morbidity and mortality in myofibrillar myopathies due to DES gene mutations: a 10-year longitudinal study

To determine incidence and type of major cardiac adverse events in patients with mutated desmin (DES) gene, we retrospectively reviewed baseline medical information, and examined the long-term outcomes of 28 DES patients (17 men, baseline mean age=37.7±14.4 years [min=9, max=71]) from 19 families. Baseline studies revealed skeletal muscle involvement in 21 patients and cardiac abnormalities in all but one patient. Over a mean follow-up of 10.4±9.4 years [min=1, max=35], cardiac death occurred in three patients, death due to cardiac comorbidities in two, one or more major cardiac adverse events in 13 patients. Among the 19 patients with mild conduction defects at baseline, eight developed high-degree conduction blocks requiring permanent pacing. Cardiac involvement was neither correlated with the type of DES mutation nor with the severity of skeletal muscle involvement. Our study underscores that in DES patients in-depth cardiac investigations are needed to prevent cardiac conduction system disease.     

Postoperative complete atrioventricular block induced by carbamazepine in a patient with congenital heart disease

We report here a boy with epilepsy and congenital heart defect, complicated postoperatively by complete atrioventricular (A-V) block caused by an adverse effect of carbamazepine (CBZ). He had been taking CBZ for 7 years to treat complex partial seizures. He also had endocardial cushion defect and first-degree A-V block, and underwent cardiac surgery at the age of 17 years. The postoperative course was unremarkable except transient complete left bundle branch block occuring one day after the surgery. Oral CBZ (400 mg per day) was continued. Five days after the surgery, bradycardia (20 beats per minute) suddenly developed, and electrocardiography (ECG) showed complete A-V block. Pervenous pacing was begun, and the heart rate gradually recovered. CBZ was discontinued on the suspicion that it caused the arrhythmia, although its serum level was estimated to be within the therapeutic range (4 to 5 microg/ml). He underwent pervenous pacing for 12 days. He was discharged 27 days after the surgery, when ECG returned to first-degree A-V block. In this case, the cardiac conduction system was affected by an adverse effect of CBZ, in combination with the preoperative first-degree A-V block and the effects of cardiac surgery, resulting in complete A-V block. Although reports of similar cases are scarce, caution should be made in prescribing CBZ to patients who either have cardiac conduction abnormalities or undergo cardiac surgery.     

Intravenous alteplase for stroke: beyond the guidelines and in particular clinical situations

BACKGROUND AND PURPOSE: Because of the risk of hemorrhage, especially in the brain, thrombolytic therapy with intravenous alteplase is restricted by guidelines, and only a small number of selected patients are being treated. Findings from metaanalyses, post hoc analyses of the randomized trials, and postlicensing experience suggest that more subjects, who otherwise have a poor predicted outcome without treatment, might benefit from intravenous alteplase. Summary of Review- There is a strong indication that treatment may still be beneficial beyond 3 hours up until 4.5 hours. The risk of symptomatic intracerebral hemorrhage is not increased in patients aged 80 years or older. Excluding patients with severe stroke or with early ischemic changes in more than one third of the middle cerebral artery territory on baseline CT scan is probably not necessary when treatment is started <3 hours of symptom onset. Patients with minor or improving symptoms can also benefit. Intravenous thrombolysis appears appropriate as first line therapy for posterior circulation stroke. Alteplase can be given to patients with cervical artery dissection, seizure at onset and evidence of acute ischemia on brain imaging, and after carefully weighing risk and benefit in pregnancy and during menstruation. There are anecdotal reports on its use in children, patients with recent myocardial infarction, cardiac embolus, intracranial aneurysm or arteriovenous malformation, prior stroke and recent surgery. There appears to be a substantially increased risk of symptomatic cerebral hemorrhage in hyperglycemic stroke patients. The combined intravenous and intraarterial approach to recanalization appears safe and is currently under investigation in a randomized trial. CONCLUSIONS: This document does not intend to change the guidelines but reviews the literature on the use of intravenous alteplase for stroke beyond guidelines and in particular conditions.     

The screening for X-linked Emery–Dreifuss muscular dystrophy amongst young patients with idiopathic heart conduction system disease treated by a pacemaker implant

The X-linked Emery-Dreifuss muscular dystrophy (X-EDMD) is a hereditary muscle disorder associated with cardiac involvement. Sinus node dysfunction and atrioventricular conduction defects, typical of X-EDMD, occur in both males and females and may result in sudden cardiac death unless treated by permanent pacing. The objective of the study was to determine the frequency and relevance of X-EDMD in heart conduction system disease in young individuals treated with a pacemaker implant. The medical history of 3450 paced individuals in the region of South Moravia, Czech republic, was reviewed. Thirty-five patients, 20 males and 15 females, with idiopathic heart conduction disease of onset before age 40 were identified and screened for X-EDMD. Within these 35 individuals, only one male was found to carry a mutation in X-EDMD gene. We conclude that the clinical relevance of X-EDMD in heart conduction system disease is very low. It should, however, be included into the diagnostic work-up of young male individuals with idiopathic cardiac conduction disturbances.     

干细胞移植与心脏生物起搏的研究现状

随着基因工程技术和分子生物学的不断发展，心脏生物起搏成为近来研究热点，目前研究主要包括细胞生物起搏和基因生物起搏。用于构建生物起搏的细胞主要包括间充质干细胞和胚胎干细胞，通过诱导分化使之成为具有起搏功能的细胞，对受损的自律性节律点或特殊传导系统的细胞进行修复或替代，使心脏的起搏和传导功能得以恢复。现阶段国内外研究主要集中在体外细胞和动物试验研究阶段，应用于临床的报道尚少。