Initial experience with a rapid access blackouts triage clinic.

Transient loss of consciousness (T-LOC), or blackout, is common in acute medicine. Clinical skills are not done well, with at least 74,000 patients misdiagnosed and mistreated for epilepsy in England alone. The aim of this study was to provide a rapid, structured assessment and an electrocardiogram (ECG) for patients with blackouts, aiming to identify high risk, reduce misdiagnoses, reduce hospital admission rates for low-risk patients, diagnose and treat where appropriate, and also provide onward specialist referral. The majority of patients had syncope, and very few had epilepsy. A high proportion had an abnormal ECG. A specialist-nurse-led rapid access blackouts triage clinic (RABTC) provided rapid effective triage for risk, a comprehensive assessment format, direct treatment for many patients, and otherwise a prompt appropriate onward referral. Rapid assessment through a RABTC reduced re-admissions with blackouts. Widespread use of the web-based blackouts tool could provide the NHS with a performance map. The U.K. has low rates of pacing compared to Western Europe, which RABTCs might help correct. The RABTC sits between first responders and specialist referral, providing clinical assessment and ECG in all cases, and referral where appropriate.

Oxygen pre-breathing decreases dysbaric diseases in UW sheep undergoing hyperbaric exposure.

Prolonged exposure of humans and animals to increased pressure as in a disabled submarine (DISSUB) can saturate the body's tissues with dissolved N2 as compressed air is breathed. Decompression-induced bubble formation in the long bone marrow cavity may lead to a bone compartment syndrome resulting in bone ischemia and necrosis. We tested oxygen pre-breathing prior to decompression in sheep to assess the effect upon dysbaric osteonecrosis (DON) induction in a DISSUB simulation experiment. A total of sixteen adult female sheep were used throughout the experiment. Four sheep were used as controls without oxygen pre-breathing. All sheep (99 +/- 14 kg SD) underwent dry chamber air exposure at 60 fsw (2.79 atm abs) (.2827 MPa) for 24 h followed by oxygen (88-92%) pre-breathing (15-min, 1-h, and 2-h and air for control) before "dropout" decompression at 30 fsw/min (0.91 atm/min). 99mTc-methylene diphosphonate (MDP) bone scans of the distal (radii and tibiae) long bones were used to detect "hot spots" of remodeling suggestive of DON lesions. Alizarin complexone fluorochrome was injected to visualize sites of metabolic activity indicating DON repair of both the proximal and distal long bones (radii, tibiae, femora, and humeri). Our findings showed that the amount of alizarin complexone deposition and bone scan uptake was greater in sheep with shorter oxygen pre-breathing times than those undergoing longer pre-breathing dives (p = 0.0056 and p = 0.001, for one and two hour pre-breathes respectively). Proximal limb bones (femur, humerus) displayed less alizarin complexone deposition than the distal radius and tibia (p < 0.0001).

Atrioventricular node reentrant tachycardia ablation in a patient with congenitally corrected transposition of the great vessels using the CARTO mapping system.

We present a case of a 21-year-old female with congenitally corrected transposition of the great vessels and episodes of supraventricular tachycardia. We performed an electrophysiological study and successful ablation using an electro-anatomical mapping system. A single His bundle appeared to be located at the apex of the triangle of Koch and at electrophysiological study there was evidence of triple antegrade AV nodal pathways--slow, intermediate and fast, with two types of AV nodal re-entrant tachycardias. A series of radiofrequency ablations in the right posteroseptal area eliminated both slow and intermediate pathway conduction and cured the tachycardias.

Optimisation of cardiac resynchronisation therapy: addressing the problem of "non-responders".

Cardiac resynchronisation therapy has become firmly established as a treatment for patients with symptomatic heart failure. Several randomised controlled trials and numerous observational studies have demonstrated improvements in exercise capacity and quality of life. Despite these advances it is clear that approximately 25% of patients who meet current criteria for implantation of such a device do not show objective evidence of clinical benefit. Implantation of a CRT device is expensive, time consuming and involves some risk so it is important to accurately identify patients who are likely to respond and to optimise pacing lead placement and device programming to maximise the benefit in these selected patients.

Comprehensive cardiac rehabilitation programme for implantable cardioverter-defibrillator patients: a randomised controlled trial.

OBJECTIVE: To investigate the effects of a 12 week comprehensive cardiac rehabilitation (CCR) programme on patients who have undergone implantation of an implantable cardioverter-defibrillator (ICD). DESIGN: Sixteen patients with ICDs (14 (88%) male, mean (SD) age 58 (10) years, range 34-74 years) were randomised to either attend an individually tailored CCR programme or receive usual care. They then changed to the alternative regimen for a further 12 weeks. Exercise capacity was assessed using a treadmill exercise test at baseline, after usual care, after CCR and 12 weeks after CCR to assess maintenance effects. Hospital anxiety and depression (HAD) scores were recorded at each stage. RESULTS: Exercise times (min:s; mean (SD)) increased by 16% from a baseline mean of 9:55 (2:33) to 11:11 (2:17) following attendance at CCR (95% confidence interval (CI) 0:34 to 1:58; p = 0.001). This improvement was maintained 12 weeks after attendance at CCR, at 11:20 (2:17) (p = 1.00). HAD scores for anxiety and depression decreased during CCR from a baseline of 13.4 (3.6) to 8.1 (3.6), 95% CI 3.5 to 7.0 (p < 0.001) and 9.9 (3.4) to 6.7 (2.9), 95% CI 1.9 to 4.4 (p = 0.002), respectively. These improvements were maintained at 12 weeks after CCR. No ventricular arrhythmias or ICD discharges occurred during the exercise components of the CCR. The total number of ventricular arrhythmias and ICD discharges was similar 12 weeks before, during, and 12 weeks after CCR. CONCLUSIONS: CCR appears to be safe for patients with ICDs. It can improve exercising ability and lower the levels of psychological distress. A larger multicentre study is recommended to confirm these findings.

The use of the Hilbert transform in ECG signal analysis.

This paper presents a new robust algorithm for QRS detection using the first differential of the ECG signal and its Hilbert transformed data to locate the R wave peaks in the ECG waveform. Using this method, the differentiation of R waves from large, peaked T and P waves is achieved with a high degree of accuracy. In addition, problems with baseline drift, motion artifacts and muscular noise are minimised. The performance of the algorithm was tested using standard ECG waveform records from the MIT-BITH Arrhythmia database. An average detection rate of 99.87%, a sensitivity (Se) of 99.94% and a positive prediction (+P) of 99.93% have been achieved against study records from the MIT-BITH Arrhythmia database. A detection error rate of less than 0.8% was achieved in every study case. The reliability of the proposed detector compares very favorably with published results for other QRS detectors.

Slow pathway modification for atrioventricular node re-entrant tachycardia: fast junctional tachycardia predicts adverse prognosis.

OBJECTIVE: To examine the cycle length of the junctional tachycardia often seen during successful slow pathway ablation for atrioventricular (AV) node re-entrant tachycardia, to determine whether shorter cycle lengths predict imminent atrioventricular block. DESIGN: Retrospective analysis of consecutive patients undergoing slow pathway modification. Intracardiac recordings were analysed after digital storage to determine the development of junctional tachycardia, its duration and maximum, minimum, and mean cycle length, occurrence of heart block, persistent slow pathway conduction, or later confirmed recurrence of AV node re-entrant tachycardia. SETTING: Regional cardiac centre. PATIENTS: 136 consecutive patients undergoing electrophysiological study found to have typical "slow-fast" AV node re-entrant tachycardia and subject to 137 slow pathway modification procedures. RESULTS: During successful temperature feedback controlled radiofrequency energy application, junctional tachycardia developed in 133 of 137 procedures. During ablation, 10 patients had evidence of AV block (first degree in seven patients and third degree in three), and 17 others had retrograde junctional atrial (JA) block. In these 27 patients, the junctional tachycardia was rapid, with a minimum (SD) cycle length 291 (47) ms. Conduction recovered quickly in all but two patients, one of whom required permanent pacing. Junctional tachycardia with normal AV and JA conduction in the other 111 patients was of a significantly slower minimum cycle length (537 (123) ms; p < 0.0001). CONCLUSIONS: Fast junctional tachycardia with cycle lengths under 350 ms seen during slow pathway modification is a predictor of conduction block, suggesting proximity to the compact node. Radiofrequency energy application should be terminated immediately to prevent development of AV block. An "auto cut off" facility for cycle lengths shorter than 350 ms could be built into radiofrequency ablation systems to increase safety.

Misdiagnosis of epilepsy: many seizure-like attacks have a cardiovascular cause.

OBJECTIVES: We sought to investigate the value of cardiovascular tests to diagnose convulsive syncope in patients with apparent treatment-resistant epilepsy. BACKGROUND: As many as 20% to 30% of epileptics may have been misdiagnosed. Many of these patients may have cardiovascular syncope, with abnormal movements due to cerebral hypoxia, which may be difficult to differentiate from epilepsy on clinical grounds. METHODS: Seventy-four patients (33 men, mean age 38.9 +/- 18 years [range 16 to 77]) who were previously diagnosed with epilepsy were studied. Inclusion criteria included continued attacks despite adequate anticonvulsant drug treatment (n = 36) or uncertainty about the diagnosis of epilepsy, on the basis of the clinical description of the seizures (n = 38). Each patient underwent a head-up tilt test and carotid sinus massage during continuous electrocardiography, electroencephalography and blood pressure monitoring. Ten patients subsequently underwent long-term electrocardiographic (ECG) monitoring with an implantable loop recorder. RESULTS: In total, an alternative diagnosis was found in 31 patients (41.9%), including 13 (36.1%) of 36 patients taking an anticonvulsant medication. Nineteen patients (25.7%) developed profound hypotension or bradycardia during the head-up tilt test, confirming the diagnosis of vasovagal syncope. One other patient had a typical vasovagal reaction during intravenous cannulation. Two patients developed psychogenic symptoms during the head-up tilt test. Seven patients (9.5%) had significant ECG pauses during carotid sinus massage. In two patients, episodes of prolonged bradycardia correlated precisely with seizures according to the insertable ECG recorder. CONCLUSIONS: A simple, noninvasive cardiovascular evaluation may identify an alternative diagnosis in many patients with apparent epilepsy and should be considered early in the management of patients with convulsive blackouts.

Coexistent atrioventricular and nodoventricular pathways in a patient with hypertrophic cardiomyopathy.

A 17-year-old girl with concentric hypertrophic cardiomyopathy presented with a wide complex tachycardia and underwent electrophysiological study. She was found to have an antidromic tachycardia utilizing a decremental atrioventricular fiber as the anterograde limb with retrograde conduction occurring through the septum. Ablation of a right free-wall pathway rendered tachycardia noninducible, yet ventricular preexcitation remained. After ablation there was evidence of a second nodoventricular connection. We believe this to be the first report of coexistent "Mahaim" fibers; one a decremental atrioventricular connection and the second nodoventricular.

Prevalence and significance of focal sources of atrial arrhythmia in patients undergoing cardioversion of persistent atrial fibrillation.

INTRODUCTION: Recent reports have high-lighted the importance of focal atrial arrhythmias as a curable cause for a group of patients with frequently recurrent paroxysmal atrial fibrillation (AF). The importance of this arrhythmia mechanism in the general population of patients with persistent AF is unknown. METHODS AND RESULTS: After successful internal cardioversion of 50 consecutive patients with persistent AF (mean age 60 years, mean duration of AF 26 months), endocardial activity in the immediate postcardioversion period was analyzed for the presence of focal atrial activity. Postcardioversion atrial arrhythmias were considered to be focal if there was evidence of a localized source of repetitive early atrial activation, either in the form of (1) self-terminating monomorphic atrial tachycardia (at least five beats) or (2) recurrences of AF with an initial atrial activation sequence (first five beats) that was both monomorphic and reproducible with repeated recurrences. Evidence for a focal atrial arrhythmia was present in 20 of the total group of 50 patients (40%). Multivariate analysis of clinical characteristics revealed the diagnosis of lone AF as the only independent predictor of a focal source of AF (P = 0.028). Thirty-nine patients were discharged from hospital in sinus rhythm. At 1-month follow-up, 25 (64%) of these 39 patients had suffered AF recurrence. The only significant predictor of AF recurrence was evidence of a focal source of atrial arrhythmia immediately after cardioversion, with a relative risk of 1.73 (range 1.1 to 2.7; P = 0.015). CONCLUSION: Focal atrial arrhythmias are common in patients presenting with "idiopathic" persistent AF, suggesting a possible causative role in the generation of this common arrhythmia.

Haemodynamic effects of increasing angle of head up tilt.

OBJECTIVE: To investigate the haemodynamic effects of varying the angle of head up tilt. METHODS: 20 healthy subjects (12 female, eight male; mean (SD) age 33.6 (8.4) years) underwent head up tilt for five minutes to each of four angles of tilt in random order, with a five minute rest period at the horizontal between each angle. Forearm blood flow was measured using intermittent occlusion mercury strain gauge plethysmography at two and five minutes. Subjects underwent continuous monitoring of heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) by Finapres and cardiac output and stroke volume by impedance cardiography. Each variable was measured at two and five minutes, averaged over the period of blood flow measurement. RESULTS: Every haemodynamic variable at each angle was significantly different from supine values. Head up tilt produced progressive increases in heart rate (11-21%), SBP (12-21%), and DBP (20-33%) with increasing tilt angle. However, although 45 degrees produced significantly less haemodynamic effect, there were no significant differences for angles between 60 degrees and 90 degrees. Cardiac output fell on head up tilt by 17-20% and stroke volume by 28-34%, but increasing tilt angle produced no significant additional reduction in cardiac output and stroke volume because of increases in heart rate and vasoconstriction. CONCLUSIONS: Angles < 60 degrees produce significantly less haemodynamic effects than steeper angles. Increasing tilt angle beyond 60 degrees produces no apparent additional effect on cardiac output or sympathetic tone. Increasing tilt angle beyond 60 degrees confers no additional orthostatic stress and may not affect the sensitivity and specificity of head up tilt testing as previously thought. Sixty degrees of tilt is a more practical angle for support of a syncopal patient and is recommended.

Good outcomes from cardiac surgery in the over 70s.

OBJECTIVE: To determine the early mortality and major morbidity associated with cardiac surgery in the elderly. DESIGN: Retrospective case record review study of 575 patients >/= 70 years old who underwent cardiac surgery at the Manchester Heart Centre between January 1990 and December 1996. SETTING: Regional cardiothoracic centre. SUBJECTS: Patients >/= 70 years old who underwent cardiac surgery. MAIN OUTCOME MEASURES: Comparison of 30 day mortality and incidence of major morbidity between patients >/= 70 years old and patients < 70 years old. RESULTS: Of 4395 cardiac surgical operations, 575 operations (13.1%) were in patients aged >/= 70 years (mean (SD) 73.1 (3.2) years). The proportion of elderly patients rose progressively from 7.9% in 1990 to 16.5% in 1996. 334 patients (58.1%) had coronary artery bypass grafting alone, 91 patients (15.8%) had valve surgery alone, and 129 patients (22.4%) had combined valve surgery and bypass grafting. For isolated coronary artery bypass grafting, 30 day mortality in patients >/= 70 years was 3.9% compared with 1.3% in patients < 70 years (p < 0.001). 30 day mortality for isolated valve surgery in patients >/= 70 years was 7.7%. Isolated aortic valve replacement was the most common valvar procedure in patients >/= 70 years and carried the lowest mortality (4.3%). Additional coronary artery bypass grafting increased the mortality rate in patients >/= 70 years to 9.3% for all valve surgery and to 8.0% for aortic valve replacement. Major morbidity in patients >/= 70 years was low for all procedure types (stroke 1.9%, acute renal failure requiring dialysis 1.6%, perioperative myocardial infarction 0.5%). CONCLUSIONS: Early mortality and major morbidity is low for cardiac surgery in elderly patients. Concerns over the risk of cardiac surgery in the elderly should not prevent referral, and elderly patients usually do well. However, unconscious rationing of health care may affect referral patterns, and studies that assess the cost effectiveness of cardiac surgery versus conservative management in such patients are lacking.

The role of atrial electrical remodeling in the progression of focal atrial ectopy to persistent atrial fibrillation.

Although atrial fibrillation- (AF) induced changes in atrial refractoriness (atrial electrical remodeling) have been demonstrated in a number of different animal models, the clinical significance of this process is unknown. We describe a patient in whom there has been documented progression of atrial ectopy to persistent AF accompanied by evidence of atrial electrical remodeling, with reversal of remodeling following successful ablation of the focal source of AF. A second patient with focal AF, but with a "nonfocal" appearance on the ECG, is also described. These cases illustrate: (1) the possibility that a significant proportion of younger patients with idiopathic persistent AF may well have a focal source as the underlying abnormality; and (2) atrial electrical remodeling reverses following ablation of the underlying source.

Who needs an implantable defibrillator?

Ventricular arrhythmias account for 80% of sudden cardiac deaths. The implantable defibrillator (ICD) is an effective means of preventing these deaths. This article discusses which patients may benefit from ICD implantation and addresses the cost-effectiveness of their use.

Transeptal approach to ablation of left-sided arrhythmias does not lead to persisting interatrial shunt: a transesophageal echocardiographic study.

In experienced hands, antegrade left heart catheterization via a transeptal puncture is a safe and effective method of performing radiofrequency ablation on the left side of the heart. Persistence of atrial septal defect following transeptal puncture for mitral valvuloplasty has been widely reported although hemodynamically significant shunts are rare. To investigate the persistence of interatrial shunt following transeptal puncture in patients undergoing left-sided electrophysiological procedures using TEE. Fifty-one adult patients, 20 men, aged 19-82 (mean 42.4) years underwent 55 transeptal punctures. Either an 8 Fr Mullins or 8 Fr Swartz transeptal sheath was deployed in all cases. Of these, 28 consecutive patients were approached and 26 consented to undergo TEE. TEE was performed at least 3 weeks post transeptal puncture using a single-plane transducer for the first 18 patients, superseded by a multiplane transducer for the later cases. Both color flow Doppler and microcavitation contrast imaging of the interatrial septum were performed. One patient in the single-plane transducer group was excluded as the failed to swallow the TEE probe. In the remaining 25 patients studied, 9 men aged 21-82 (mean 44.1) years, TEE was performed at a mean of 12.2 (range 3-52) weeks post procedure. No evidence of interatrial shunt was detected by either color flow or contrast studies. Transeptal puncture used in electrophysiological procedures does not result in interatrial shunts persisting > 3 weeks post procedure.

The transseptal approach for ablation of cardiac arrhythmias: experience of 104 procedures.

OBJECTIVE: To report retrospectively on the training and subsequent experience of two operators in transseptal ablation of arrhythmias arising in the left atrium and left atrioventricular annulus, to show whether, with adequate training and careful attention to detail, this is a safe and effective technique. SETTING: Electrophysiological studies and transseptal procedures were performed in the electrophysiology laboratories of the Moffatt Hospital, University of California at San Francisco (39) and Manchester Royal Infirmary (65) from January 1993 to June 1997. Close supervision by a fully trained operator was provided for at least the first 20 procedures performed by each operator. PATIENTS: 94 consecutive patients underwent electrophysiological study and ablation for Wolff-Parkinson-White syndrome with left sided accessory connections (81 patients) or ectopic atrial tachycardia (13 patients); 104 transseptal procedures were done; eight patients required multiple procedures. RESULTS: 92 patients (98%) were initially successfully ablated. Five of 81 with accessory pathways (6%) and three of 13 with atrial tachycardia (23%) required further procedures. One patient with Wolff-Parkinson-White syndrome could not be ablated at a second procedure. Long term success rate for accessory pathway ablation was therefore 99%. Procedures were abandoned in three patients because of minor complications. All were subsequently ablated successfully by a transseptal approach on another day. CONCLUSIONS: The transseptal approach is safe and effective for ablation of left sided arrhythmias. The technique has similar success rates to the retrograde transaortic approach but without the risk of inadvertent damage to the coronary arteries or aortic valve.

Subpectoral implantation of a cardioverter defibrillator under local anaesthesia.

OBJECTIVE: To evaluate patient acceptability of submuscular implantation of a cardioverter defibrillator (ICD) under local anaesthesia with conscious sedation. DESIGN: Retrospective review. Patient acceptability in the second half of the study was routinely assessed within 24 hours. SETTING: Regional cardiac centre. PATIENTS: 45 consecutive patients with either aborted sudden death or haemodynamically unstable ventricular tachycardia were referred for ICD implantation. INTERVENTIONS: A subpectoral implantation technique was employed. Twelve procedures were performed under general anaesthesia. Thirty three patients were sedated with midazolam and diamorphine, and local anaesthesia was achieved with bupivicaine. Ventricular fibrillation for defibrillation threshold testing was induced by alternating current, T wave shock, or ultrarapid burst pacing. Patients were contacted after the procedure to assess acceptability. RESULTS: 32 patients having implantation under local anaesthesia did not recall the surgical procedure. One patient described an awareness of "pushing" as the generator was positioned in the pocket. Seven patients said that the procedure was painless but recalled a test shock, four describing it as mildly uncomfortable. All 33 patients stated that they would be willing to have a second implant under local anaesthesia. Twelve patients who had the implant performed under general anaesthesia had no recollection of the procedure. Mean (SD) total procedure duration was significantly longer in those who had general anaesthesia (93 (16) v 67 (17) minutes; p = 0.0009). CONCLUSIONS: Subpectoral implantation of ICDs may be performed safely with patient acceptability under local anaesthesia with conscious sedation.