High altitude arrhythmias.

OBJECTIVE: To investigate the cause and nature of palpitations occurring at high altitude. METHODS: Implantable loop recorders were inserted subcutaneously in the left pectoral region of 9 healthy male volunteers. Subjects flew to Kathmandu (1,250 m) and then Lukla (2,800 m) before immediately commencing an identical ascent and descent profile to high altitude. The loop recorders were activated with any episode of palpitations and during exercise, rest and sleep. Arterial oxygen saturation was assessed concomitant with device activation. RESULTS: Above 5,000 m all subjects reported palpitations during exercise. All subjects demonstrated sinus tachycardia and marked sinus arrhythmia; one subject demonstrated atrial flutter; one subject had non-conducted p waves, and a further subject had marked ST segment depression. CONCLUSIONS: Significant arrhythmias occur at high altitude. In view of the increased risk of sudden cardiac death at high altitude, and considering that the elderly account for 15% of the 100 million visitors to altitude annually, further investigation is required.

Intravenous amiodarone for the pharmacological termination of haemodynamically-tolerated sustained ventricular tachycardia: is bolus dose amiodarone an appropriate first-line treatment?

OBJECTIVE: To examine the efficacy of bolus dose intravenous amiodarone for the pharmacological termination of haemodynamically-tolerated sustained monomorphic ventricular tachycardia (VT). DESIGN, SETTING AND PARTICIPANTS: Retrospective case series of consecutive emergency admissions with haemodynamically-tolerated sustained monomorphic VT administered bolus dose intravenous amiodarone 300 mg, according to current UK advanced life support practice guidelines. MAIN OUTCOME MEASURES: Pharmacological termination rates within 20 min and 1 h and incidence of hypotension requiring emergency direct current cardioversion (DCCV) during this period. RESULTS: 41 patients (35 men) of mean (SD) age 68 (10) years, the majority (85%) with ischaemic heart disease and impaired left ventricular function (mean (SD) ejection fraction 0.31 (0.11)), were enrolled in the study. The median VT duration was 70 min (range 15-6000), mean heart rate was 174 (34) bpm and systolic and diastolic blood pressures were 112 (22) and 73 (19) mm Hg, respectively. Pharmacological VT termination occurred within 20 min in 6/41 patients (15%; 95% CI 7% to 29%) and within 1 h in 12/41 patients (29%; 95% CI 18% to 45%). Haemodynamic deterioration requiring emergency DCCV occurred in 7/41 patients (17%; 95% CI 8% to 32%). CONCLUSIONS: Although advocated by advanced life support guidelines, bolus dose intravenous amiodarone was relatively ineffective for acutely terminating haemodynamically-tolerated sustained monomorphic VT with a significant incidence of haemodynamic destabilisation requiring emergency DCCV. Previous studies in the identical clinical setting suggest that alternative antiarrhythmic agents, particularly intravenous procainamide and sotalol, may be superior. A prospective randomised trial is required to determine the optimal drug treatment for stable sustained monomorphic VT in the emergency setting.

Treatment strategies in atrial fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice affecting up to 1% of the general population. There is a higher prevalence and incidence with increasing age and burden of chronic heart disease . Treatment for AF represents a significant healthcare cost, estimated to be about Euro 13.5 billion annually in the European Union. Manage-ment of AF remains challenging especially with new pharmacological and non-pharmacological approaches becoming readily available. This review article discusses the multitude of therapeutic options and how they may be applied to best effect.

Characteristics of non-vitreoretinal ocular injury in child maltreatment: a systematic review.

PurposeTo identify the spectrum of non-vitreoretinal ocular injury due to child maltreatment.MethodsAll language search of MEDLINE, PsychINFO, EMBASE, AMED, Web of Science, and CINAHL databases, 1950-2015, was conducted. INCLUSION CRITERIA: explicit confirmation of injury aetiology, age <18 years, examination conducted by an ophthalmologist. Exclusion: post-mortem data, organic diseases, review articles. Standardised critical appraisal and narrative synthesis was conducted of included publications by two independent reviewers.ResultsOf 1492 studies identified, 153 full texts were assessed, 49 underwent full review, resulting in five included studies: three case series and two case reports. The 26 included cases describe a wide variety of ocular, facial and skeletal injuries occurring as a consequence of child maltreatment. Ocular signs included periorbital oedema, chemosis, injection, abrasion, hyphaema, and cataract. Of interest all children that had suffered physical abuse with ocular injury had subconjunctival haemorrhages. Children presenting with abusive ocular injuries had a mean age of 13.9 months (range 1-68), while those who suffered violent corporal punishment were considerably older (mean 96 months). All cases, apart from severe corporal punishment, underwent screening for occult fractures, but neuroimaging only apparent in 2/5 eligible cases.ConclusionAlthough, the face is the most common site of abusive injury, there is a paucity of high-quality data on non-vitreoretinal ocular abusive injury. Thus, while subconjunctival haemorrhages are a potential sentinel injury of maltreatment, and may warrant further evaluation, the lack of large-scale published data limits our ability to highlight further specific characteristics of non-vitreoretinal ocular injury indicative of child abuse.

Electrophysiological mapping and ablation of intra-atrial reentry tachycardia after Fontan surgery with the use of a noncontact mapping system.

BACKGROUND: Atrial tachyarrhythmias are a complication of Fontan surgery. Conventional electrophysiological mapping and ablation techniques are limited by the complex anatomic and surgical substrate and a high arrhythmia recurrence rate. This study investigates the use of noncontact mapping to identify arrhythmia circuits and guide ablation in Fontan patients. METHODS AND RESULTS: Eleven arrhythmias were recorded in 6 patients. Noncontact mapping improved recognition of the anatomic and surgical substrate and identified exit sites from zones of slow conduction in all clinical arrhythmias. Radiofrequency linear lesions were targeted across these critical zones in 5 patients. One patient underwent surgical cryotherapy. Although immediate success was achieved in 3 of 5 patients with radiofrequency ablation, 2 patients had a recurrence after a mean of 6.4 months of follow-up. The patient who underwent cryoablation remains free of arrhythmias. CONCLUSIONS: Noncontact mapping can identify arrhythmia circuits in the Fontan atrium and guide placement of ablation lesions. Arrhythmia recurrence is high, possibly because of inadequate lesion creation rather than inaccurate mapping and lesion targeting.

Buffering capacity of the smoke of different tobaccos in relation to lung cancer risks.

A method of assessing "buffering capacity" is described for comparison of the degree of acidity of alkalinity of the smoke of different tobaccos as presented to the oral and respiratory tracts of the smoker. Nicotine is more readily absorbed from an alkaline than from an acid smoke. The smoker of tobaccos giving a smoke of acid buffering capacity, in order to achieve full nicotine satisfaction, tends to smoke more and to inhale more, thus increasing lung cancer risks, than the smoker of tobaccos giving smoke of less acid or of alkaline buffering capacity.

The effects of four antihypertensive agents on the Stroop colour-word test in normal male volunteer subjects.

Sixty healthy male volunteers were randomly assigned to one of six treatment groups on a double-blind basis: 1. Atenolol = 50 mg t.d.s. 2. Methyl dopa = 250 mg t.d.s. 3. Propanolol = 40 mg t.d.s. 4. Reserpine = 0.2 mg t.d.s. 5. Placebo. 6. Control = no tablets. Tests were carried out before treatment, 2 h after the first dose, after seven doses, and after 21 doses. Subjects performance on the Stroop Colour-Word Test was assessed in terms of (a) word reading speed and (b) an 'interference' score based on the difference between the incongruous colour word and colour card reading speed. No evidience was found of central effects of the beta-blockers, but personality X drug interactions were found, particularly in the reserpine group.

The effects of two antidepressants, imipramine and viloxazine, upon driving performance.

Forty male volunteers were randomly assigned to one of four treatment groups on a double-blind basis: (1) Imipramine--25 mg t.d.s., (2) Viloxazine--50 mg t.d.s., (3) Placebo, and (4) Control--no tablets. Tests were carried out (1) before treatment, (2) 2 h after the first dose, (3) on Day 3 after 7 doses, and (4) on Day 7 after 21 doses. The driving tasks consisted of (1) weaving around a series of bollards while simultaneously responding to an auditory logic task and (2) a gap acceptance task. Using an analysis of covariance repeated measures design, it was found that imipramine tended to increase the level of risk acceptable to the subject as compared to either placebo or control. Imipramine also impaired performance on other tasks. Viloxazine appeared to be little different from either placebo or control on any of the tasks.

Sudden death in epilepsy: can any lessons be learned from convulsive therapy?

Convulsive therapy (chemically or electrically induced) has been used since the mid-1930s. Initially it had a high mortality rate, but this has been falling slowly in response to refinements in technique (introduction of muscle paralysis during the seizure, brief intravenous general anesthesia and, more recently, the acceptance that adequate ventilation and oxygenation are necessary during the procedure). Mortality during convulsive therapy has been ascribed to both cardiac and respiratory causes (particularly acute arrhythmias and pulmonary edema). There is some evidence that supporting respiration during and after the convulsion has reduced mortality significantly, such that electrical convulsive therapy is now a very low-risk procedure, even in the very elderly. This gives tenuous support for the view that death in epileptic seizures may be of respiratory origin.

Comparison of vessel contrast measured with a scanning-beam digital x-ray system and an image intensifier/television system.

Vessel contrast was measured in the fluoroscopic images produced by a scanning-beam digital x-ray (SBDX) system and an image intensifier/television (II/TV) based system. The SBDX system electronically scans a series of pencil x-ray beams across the patient, each of which is directed at a distant small-area detector array. The reduction in detected scatter achieved with this geometry was expected to provide an increase in image contrast. Vessel contrast was evaluated from images of a phantom containing iodinated tubes. The vessels were inserted into an acrylic stack to provide a patient-mimicking scattering medium. Vessel diameter ranged from 0.3 to 3.1 mm. Images were acquired at 100 kVp with the SBDX and II/TV systems and averaged to reduce x-ray noise. The II/TV system was operated in the 6-in. image intensifier mode with an anti-scatter grid. The increase in contrast in the SBDX images, expressed as a ratio of the measured SBDX and II/TV contrasts, ranged from 1.63 to 1.79 for individual vessels. This agreed well with a prediction of the contrast improvement ratio for this experiment, based on measurements of the scatter fraction, object-plane line spread functions, and consideration of the source spectrum and detector absorption properties. The predicted contrast improvement ratio for SBDX relative to II/TV images was 1.62 to 1.77.

Chemical characterisation of the different types of volatile oil constituents by various solute retention ratios with the use of conventional and novel commercial gas chromatographic stationary phases.

Retention ratios of an unknown solute peak from a volatile oil can help to identify its chemical type. Relative retentions on conventional stationary phases can be used to calculate a polar/non-polar ratio which may suggest it is an aromatic solute or a sesquiterpene hydrocarbon. With dipentyl (DA) cyclodextrin phases, gamma-DA/alpha-DA ratios can indicate a bicyclic or monocyclic monoterpenoid. Temperature change on alpha-DA can pick out a non-alcoholic saturated cyclic monoterpenoid, using 150/125 degrees C. Twenty retention ratios are reviewed involving various phases, including other modified cyclodextrins, liquid crystals, "Chirasil-Val" and crown ethers. Applications to six volatile oils are made using a variety of phases.

Comparison of coronary venous defibrillation with conventional transvenous internal defibrillation in man.

OBJECTIVE: Animal studies have shown that defibrillation in coronary veins is more effective than in the right ventricle. We aimed to assess the feasibility of placing defibrillation electrodes in the middle cardiac vein (MCV) in man and its impact on defibrillation requirements. METHODS: A prospective randomised study conducted in a tertiary referral centre. 10 patients (9 male) undergoing ICD implantation (65 (12) yrs) for NASPE/BPEG indications were studied. Defibrillation thresholds (DFT) were measured, using a binary search and an external defibrillator after 10 seconds of ventricular fibrillation, for the following configurations in each patient (order of testing randomised): RV + MCV --> Can and RV --> SVC + Can. INTERVENTIONS: A dual coil defibrillation electrode was placed transvenously in the right ventricle (RV) in the conventional manner. Using a guiding catheter a 3.2 Fr (67.5 mm length) electrode was placed transvenously in MCV. A test-can was placed subcutaneously in the left pectoral region. RESULTS: Lead placement was possible in 8/10 pts. Time to perform a middle cardiac venogram and place the electrode was 21 (23) mins. No adverse events were observed. Defibrillation current was less (6.7 (2.7) A) with RV + MCV --> Can compared to the conventional RV --> SVC + Can configuration (8.9 (3.4) A, p = 0.03). There was no significant difference in defibrillation voltage or energy. However, shock impedance was higher in the former configuration (57 (10) v. 43 (6) Omega, p = 0.001). CONCLUSIONS: In the majority of cases placement of a defibrillation lead in MCV is feasible. Defibrillation current requirements are 25% less when the shock is delivered using a MCV electrode.

Increased defibrillation threshold with right-sided active pectoral can.

UNLABELLED: The aim of this study was to identify the optimal position on the chest wall to place an implant able cardioverter defibrillator in a two-electrode system, consisting of a right ventricular electrode and active can. METHODS AND RESULTS: Defibrillation thresholds (DFT) were measured in 10 anaesthetised pigs (weight 33-45 kg). An Angeflextrade mark lead was introduced transvenously to the right ventricular apex. The test-can (43 cc) was implanted submuscularly in each of four locations: left pectoral (LP), right pectoral (RP), left lateral (LL) and apex (A). The sequence in which the four locations were tested was randomized. Ventricular fibrillation (VF) was induced using 60 Hz alternating current. Rectangular biphasic shocks were delivered 10 seconds after VF induction. The DFT was measured using a modified four-reversal binary search. The results of the four configurations were: LP, 14.6+/- 4.0 J; RP, 18.8+/- 4.2 J; LL, 14.7+/- 4.1 J; A, 14.9+/- 3.1 J. Repeated measures analysis of variance showed that the DFT of RP was significantly higher than LP, LL and A (p < 0.05). CONCLUSIONS: Implanting an active can in the RP position increases the DFT by 29% compared to LP, LL and A sites. The can position on the left thorax does not appear to have a significant influence on DFT.

Single capacitive discharge utilizing an auxiliary shock in the coronary venous system reduces the defibrillation threshold.

UNLABELLED: Auxiliary shocks (AS) from electrodes sutured to the left ventricle (LV) prior to primary biphasic shocks (PS) have been shown to reduce defibrillation thresholds (DFT). Two capacitors are required to generate these waveforms. We investigate delivery of AS from one capacitor using a novel waveform. The epicardial surface of the LV is accessed transvenously via the middle cardiac vein (MCV) avoiding a thoracotomy. METHODS: A defibrillation electrode was placed in the right ventricle (RV) and superior vena cava (SVC) in 12 pigs (37+/-2 kg). A 50x1.8 mm electrode was inserted in the MCV through a guide catheter. A can was placed in the left pectoral region. A monophasic AS (100 microF, 1.5 J) was delivered along one pathway before switching to deliver a biphasic waveform (40% tilt, 2 ms phase 2) along another. DFTs (PS+AS) were assessed using a binary search. Two configurations not incorporating AS acted as controls. DFTs were compared using repeated measures analysis of variance. RESULTS: DFTs of the four novel configurations (AS/PS) were: RV-->Can/MCV-->Can=14.9+/-3.7 J, MCV-->Can/RV-->Can=17.2+/-5.7 J, RV-->SVC+Can/MCV-->SVC+Can=13.4+/-4.6 J, MCV-->SVC+Can/RV-->SVC+Can=17.1+/-5.9 J. Delivering AS in the RV followed by PS in the MCV reduced the DFT (RV-->Can (19.9+/-7.3 J, P<0.01) and RV-->SVC+Can (19.2+/-6.0 J, P<0.05)). CONCLUSIONS: Delivering AS prior to PS in the MCV reduces the DFT by up to a third compared to conventional configurations of RV-->Can and RV-->SVC+Can. This is possible using only a single capacitor and an entirely transvenous approach to the LV.

New method for testing the absorbency of surgical dressings.

Absorbent cellulose dressings have been tested by immersion in a standard aqueous solution of picric acid followed by standard draining, elution of the picric acid, and measurement of the absorbance of the yellow colour at 355 nm. Six samples of gauze were graded by this procedure, and two considered unsatisfactory, despite all sinking in less than 10s. Filmated gauzes and unwoven dressings required greater dilution for the absorbance readings, reflecting their different structures.

Epilepsy--doctor's dilemma, lawyer's delight? Medico-legal consequences of practising in the field of epilepsy report of an International League Against Epilepsy British Branch meeting--Edinburgh, April 2000.

Six cases are described where the medical management of a person's epilepsy was brought under legal scrutiny. Lessons learnt from this educational exercise include improving doctor patient communication, the function of a Coroner's Court, when is misdiagnosis negligent, the vagaries of expert witnesses, should failure to diagnose a tumour be blamed on the physician or the service when facilities are inadequate, is failure to recognise a rare drug interaction, failure to warn against an interaction, or failure to take a proper history, negligent? The conference also examined the legal ramifications of the nurse/doctor relationship in epilepsy care, the place of epilepsy guidelines and, due to its interactive nature, reflected on the audience's epilepsy knowledge, which, in places seemed significantly deficient. It was a gripping educational exercise.

Epileptic seizures induced by sexual abuse. Pathogenic and pathoplastic factors.

Previous sexual abuse is now thought to be a common cause of non-epileptic seizures (pseudoseizures). However, since sexual abuse is common, a previous history of sexual abuse may also occur in people with actual epilepsy. We present six patients in all of whom sexual abuse may, by acting as a stressor in the already predisposed, have precipitated epilepsy and in some of whom the abuse may have affected the actual experiences of the epilepsy itself: all but one of the patients had partial seizures.

Diagnosis, management and prognosis of a group of 128 patients with non-epileptic attack disorder. Part I.

Three hundred and forty three patients with attack disorder labelled as epilepsy were admitted for assessment to a Neuropsychiatry ward in a small English mental hospital over a 5 year period. After assessment it was decided that 63% (215) of these patients had epilepsy, but in 128 (37%) a diagnosis of non-epileptic seizures was made. Just over a third of these patients (46) had an additional history of present or past epileptic seizures as well, so that 24% of the total population had non-epileptic seizures only. The methods used to make this diagnosis are reviewed and an attempt made to classify the non-epileptic attacks from which the patients were suffering. A variety of management strategies were offered and at discharge from hospital the majority of patients had practically lost their non-epileptic seizures. At follow-up 2 years later, seizures had returned in most patients. In 8% of the patients it was clear that the diagnosis of non-epilepsy had been erroneous. The importance of classifying the kind of non-epileptic event the patient suffers from and of translating treatment in hospital to the community is emphasized.

Diagnosis, management and prognosis of a group of 128 patients with non-epileptic attack disorder. Part II. Previous childhood sexual abuse in the aetiology of these disorders.

In a group of female in-patients clinically diagnosed as having non-epileptic attack disorder there was an increased incidence of a proven previous history of sexual abuse in childhood, when compared with a group of women with epilepsy and a group of women with other psychiatric disorders admitted to the same ward. This was particularly true of women with the 'swoon' and 'abreactive' type of non-epileptic attack disorder (see Part I). The incidence of a history of previous abuse was similar to the two control groups for other types of non-epileptic attack disorder. The swoon was seen as a cut-off phenomenon: the abreactive attack as a kind of acting out the memory of the abuse, part of a post-traumatic stress disorder. Both may respond to counselling for the abuse although it is too early to be certain, and there is a risk of further episodes of the non-epileptic attack disorder during periods of stress. Some patients with epilepsy, however, also had a history of previous sexual abuse: in some the stress of the abuse may have precipitated the epileptic seizures.

Seizure behaviour in a patient with post-traumatic stress disorder following rape. Notes on the aetiology of 'pseudoseizures'.

A patient is described who began to have paroxysmal convulsive behaviour, followed by a post-ictal aggression, which was initially diagnosed and treated as epilepsy. The behaviour began after the patient was raped. She had many of the symptoms of post-traumatic stress disorder. It is suggested that the paroxysmal behaviour was an 'acting out' of intrusive and vivid memories of the rape, so called 'flashbacks'. Because the rape had occurred comparatively recently and the events that occurred during the rape were known, it was easy, in this particular patient, to understand the relationship between the previous trauma and the paroxysmal behaviour. The case throws some light on the relationship between similar paroxysmal behaviour in the victims of child sexual abuse and the trauma they had suffered and explains why they behave in the way that they do.