Diagnostic yield of an ambulatory patch monitor in patients with unexplained syncope after initial evaluation in the emergency department: the PATCH-ED study.

OBJECTIVES: Diagnosing underlying arrhythmia in ED syncope patients remains problematic. This study investigates diagnostic yield, event prevalence, patient satisfaction and compliance, and influence on resource utilisation of an ambulatory patch monitor in unexplained ED syncope patients. METHODS: Prospective pilot study conducted in a single tertiary ED in Scotland between 17 November 2015 and 16 June 2017 with a historical unmatched comparator group. Patients 16 years or over presenting within 6 hours of unexplained syncope were fitted in the ED with an ambulatory patch ECG recorder (Zio XT monitor), which continuously records a single-lead ECG for up to 14 days. Patients with an obvious underlying cause were excluded. An unmatched historical group of 603 syncope patients with no obvious diagnosis in ED, recruited to a prior cohort study (2007-2008), were used as a comparator. Primary endpoint was symptomatic significant arrhythmia at 90-day follow-up. RESULTS: During the prospective study period, 86 patients were recruited. 90-day diagnostic yield for symptomatic significant arrhythmia was 10.5% (95% CI 4.0 to 16.9; 9 of 86) versus 2.0% (95% CI 0.9 to 3.1; 12 of 603) in the comparator group. 24 patients (27.9%) had a significant arrhythmia (five serious); 26 patients (30.2%) had serious outcomes (major adverse cardiac event and/or death). Blinded patch report review suggested the patch would significantly reduce requirement for standard outpatient ambulatory ECG monitoring. 56 of 76 returned patches had a diagnostic finding within±45 s of a triggered/diary event (73.7% diagnostic utility; 95% CI 63.7 to 83.6); 34 of 56 (61%) for sinus rhythm or ectopic beats only. CONCLUSIONS: Routine, early ambulatory ECG monitoring in ED patients with unexplained syncope is probably warranted. A large-scale trial comparing this approach to standard care with cost-effectiveness and safety analysis is now required. TRIAL REGISTRATION: NCT02683174.

Systematic hand-held echocardiography in patients hospitalized with acute coronary syndrome.

AIMS: Transthoracic echocardiography is recommended in all patients with acute coronary syndrome but is time-consuming and lacks an evidence base. We aimed to assess the feasibility, diagnostic accuracy, and time efficiency of hand-held echocardiography in patients with acute coronary syndrome and describe the impact of echocardiography on clinical management in this setting. METHODS AND RESULTS: Patients with acute coronary syndrome underwent both hand-held and transthoracic echocardiographies with agreement between key imaging parameters assessed using kappa statistics. The immediate clinical impact of hand-held echocardiography in this population was systematically evaluated. Overall, 262 patients (65 ± 12 years, 71% male) participated. Agreement between hand-held and transthoracic echocardiographies was good-to-excellent (kappa 0.60-1.00) with hand-held echocardiography having an overall negative predictive value of 95%. Hand-held echocardiography was performed rapidly (7.7 ± 1.6 min) and completed a median of 5 (interquartile range 3-20) h earlier than transthoracic echocardiography. Systematic hand-held echocardiography in all patients with acute coronary syndrome identified an important cardiac abnormality in 50%, and the clinical management plan was changed by echocardiography in 42%. In 85% of cases, hand-held echocardiography was sufficient for patient decision-making, and transthoracic echocardiography was no longer deemed necessary. CONCLUSION: In patients with acute coronary syndrome, hand-held echocardiography provides comparable results to transthoracic echocardiography, can be more rapidly applied, and gives sufficient imaging information for decision-making in the vast majority of patients. Systematic echocardiography has clinical impact in half of patients, supporting the clinical utility of echocardiography in this population and providing an evidence base for current guidelines.

Multicentre open label randomised controlled trial of immediate enhanced ambulatory ECG monitoring versus standard monitoring in acute unexplained syncope patients: the ASPIRED study.

INTRODUCTION: Diagnosing underlying arrhythmia in emergency department (ED) syncope patients is difficult. There is a evidence that diagnostic yield for detecting underlying arrhythmia is highest when cardiac monitoring devices are applied early, ideally at the index visit. This strategy has the potential to change current syncope management from low diagnostic yield Holter to higher yield ambulatory monitoring, reduce episodes of syncope, reduce risk of recurrence and its potential serious consequences, reduce hospital admissions, reduce overall health costs and increase quality of life by allowing earlier diagnosis, treatment and exclusion of clinically important arrhythmias. METHODS AND ANALYSES: This is a UK open prospective parallel group multicentre randomised controlled trial of an immediate 14-day ambulatory patch heart monitor vs standard care in 2234 patients presenting acutely with unexplained syncope. Our patient focused primary endpoint will be number of episodes of syncope at 1 year. Health economic evaluation will estimate the incremental cost per syncope episode avoided and quality-adjusted life year gained. ETHICS AND DISSEMINATION: Informed consent for participation will be sought. The ASPIRED trial received a favourable ethical opinion from South East Scotland Research Ethics Committee 01 (21/SS/0073). Results will be disseminated via scientific publication, lay summary and visual abstract. TRIAL REGISTRATION NUMBER: ISRCTN 10278811.

Identification of atrial fibrillation in secondary care diabetes and vascular clinics: a pilot study.

Aim: To determine the feasibility and utility of the AliveCor® handheld ECG device in screening for asymptomatic atrial fibrillation in high-risk patients attending secondary care clinics. Materials & methods: Patients were recruited from diabetes and vascular outpatient clinics, and the AliveCor device used to store a 30-second ECG recording. Clinical risk stratification systems (CHAD2S2-VASc and HAS-BLED) assessed individual suitability for oral anticoagulation. Results: Atrial fibrillation was detected in 2 of 149 patients (1.3%), with CHA2DS2-VASc-derived annual stroke risk of 4%. Given low bleeding susceptibility (HAS-BLED), oral anticoagulation was strongly indicated. Conclusion: AliveCor technology offers a simple approach to retrieve large volumes of ECG data. A follow-up study with a larger cohort would reinforce the clinical utility of screening this high-risk population.

Atrial fibrillation case finding in over 65 s with cardiovascular risk factors - Results of initial Scottish clinical experience.

BACKGROUND: Atrial fibrillation (AF) is a major preventable risk factor for stroke and may be silent in elderly individuals who are at especially high risk. This paper describes the first phase of implementation of a clinical AF detection programme in a community setting. Objectives were (i) to determine the feasibility of using a handheld ECG recording system for AF detection among individuals aged 65 years or more, who have cardiovascular risk factors. (ii) to estimate the yield of previously undiagnosed atrial fibrillation cases, and the proportion of these who would be suitable for oral anticoagulation. METHODS: a handheld ECG monitor was placed in each of 23 primary care practices across Scotland. Eligible patients attending for annual health checks had ECGs recorded, and the ECGs were transmitted and interpreted by two senior cardiologists. ECG quality was rated, and an adjudication made on the rhythm. For patients confirmed with AF, stroke and bleeding risk were estimated using CHA2DS2-VASc and HAS-BLED scoring tools. RESULTS: single lead ECGs were recorded in 1805 patients (703 female and 1102 male), mean (SD) age 74.9 (7.1) years. Rhythm regularity could be assessed in 98.7% of ECGs recorded. 92 patients (5.1%) were found to have AF. Median [range]CHA2DS2-VASc score was 4 ([2-7) and median [range] HAS-BLED score was 2 (1-5). CONCLUSION: handheld ECG recording can be used to identify AF in the primary care setting, with minimal training. The yield was relatively high.

Complications and prognosis of patients undergoing apical or septal right ventricular pacing.

Objectives: Optimal right ventricular lead placement remains controversial. Large studies investigating the safety and long-term prognosis of apical and septal right ventricular lead placement have been lacking. Methods: Consecutive patients undergoing pacemaker insertion for high-degree atrioventricular block at Edinburgh Heart Centre were investigated. Periprocedural 30-day complications were defined (infection/bleeding/pneumothorax/tamponade/lead displacement). Long-term clinical outcomes were obtained from the General Register of Scotland and electronic medical records. The primary endpoint was a composite of all-cause mortality, new heart failure, hospitalisation for a major cardiovascular event, as per the CArdiac REsynchronization in Heart Failure trial. Secondary endpoints were all-cause mortality, new heart failure and their composite. Results: 820 patients were included, 204 (25%) paced from the septum and 616 (75%) from the apex. All baseline variables were similar with the exception of age (septal: 73.2±1.1 vs apical: 76.9±0.5 years, p<0.001). Procedure duration (58±23 vs 55±25 min, p=0.3), complication rates (18 (8.8) vs 46 (7.5)%, p=0.5) and postimplant QRS duration (152 (23) vs 154 (27) ms, p=0.4) were similar. After 1041 days (IQR 564), 278 patients met the primary endpoint, with no difference between the septal and apical groups in unadjusted (HR 0.86 (95% CIs 0.64 to 1.15)) or multivariable analysis correcting for age, gender and comorbidity (HR 0.97 (95% CI 0.72 to 1.30)). Similarly, no differences were observed in the secondary endpoints. Conclusions: This large real-world cohort of patients undergoing right ventricular lead placement in the septum or apex demonstrated no difference in procedural complications nor long-term clinical outcomes. Both pacing strategies appear reasonable in routine practice.

Multi-centre Randomised Controlled Trial of a Smartphone-based Event Recorder Alongside Standard Care Versus Standard Care for Patients Presenting to the Emergency Department with Palpitations and Pre-syncope: The IPED (Investigation of Palpitations in the ED) study.

BACKGROUND: Patients with palpitations and pre-syncope commonly present to Emergency Departments (EDs) but underlying rhythm diagnosis is often not possible during the initial presentation. This trial compares the symptomatic rhythm detection rate of a smartphone-based event recorder (AliveCor) alongside standard care versus standard care alone, for participants presenting to the ED with palpitations and pre-syncope with no obvious cause evident at initial consultation. METHODS: Multi-centre open label, randomised controlled trial. Participants ≥ 16 years old presenting to 10 UK hospital EDs were included. Participants were randomised to either (a) intervention group; standard care plus the use of a smartphone-based event recorder or (b) control group; standard care alone. Primary endpoint was symptomatic rhythm detection rate at 90 days. Trial registration number NCT02783898 (ClinicalTrials.gov). FINDINGS: Two hundred forty-three participants were recruited over an 18-month period. A symptomatic rhythm was detected at 90 days in 69 (n = 124; 55.6%; 95% CI 46.9-64.4%) participants in the intervention group versus 11 (n = 116; 9.5%; 95% CI 4.2-14.8) in the control group (RR 5.9, 95% CI 3.3-10.5; p < 0.0001). Mean time to symptomatic rhythm detection in the intervention group was 9.5 days (SD 16.1, range 0-83) versus 42.9 days (SD 16.0, range 12-66; p < 0.0001) in the control group. The commonest symptomatic rhythms detected were sinus rhythm, sinus tachycardia and ectopic beats. A symptomatic cardiac arrhythmia was detected at 90 days in 11 (n = 124; 8.9%; 95% CI 3.9-13.9%) participants in the intervention group versus 1 (n = 116; 0.9%; 95% CI 0.0-2.5%) in the control group (RR 10.3, 95% CI 1.3-78.5; p = 0.006). INTERPRETATION: Use of a smartphone-based event recorder increased the number of patients in whom an ECG was captured during symptoms over five-fold to more than 55% at 90 days. This safe, non-invasive and easy to use device should be considered part of on-going care to all patients presenting acutely with unexplained palpitations or pre-syncope. FUNDING: This study was funded by research awards from Chest, Heart and Stroke Scotland (CHSS) and British Heart Foundation (BHF) which included funding for purchasing the devices. MR was supported by an NHS Research Scotland Career Researcher Clinician award.

Multi-centre randomised controlled trial of a smart phone-based event recorder alongside standard care versus standard care for patients presenting to the Emergency Department with palpitations and pre-syncope - the IPED (Investigation of Palpitations in the ED) study: study protocol for a randomised controlled trial.

BACKGROUND: Palpitations and pre-syncope are together responsible for 300,000 annual Emergency Department (ED) attendances in the United Kingdom (UK). Diagnosis of the underlying rhythm is difficult as many patients are fully recovered on ED arrival; and examination and presenting electrocardiogram (ECG) are commonly normal. The only way to establish the underlying heart rhythm is to capture an ECG during symptoms. Recent technology advances have led to several novel ECG monitoring devices appearing on the market. This trial aims to compare the symptomatic rhythm detection rate at 90 days of one such smart phone-based event recorder (AliveCor Heart Monitor and AliveECG) with standard care for participants presenting to the ED with palpitations and pre-syncope and no obvious cause in the ED. METHODS/DESIGN: This is a multi-centre hospital ED / Acute Medical Unit (AMU) open label, randomised controlled trial. Participants will be recruited in 10 tertiary and district general hospitals in the UK. Participants aged ≥ 16 years presenting with an episode of palpitations or pre-syncope with no obvious cause and whose underlying ECG rhythm during these episodes remains undiagnosed after clinical assessment will be included. Participants will be randomised to either: (1) the intervention arm, standard care plus the use of a smart phone-based event recorder; or (2) the control arm, standard care. Primary endpoint will be symptomatic rhythm detection rate at 90 days. A number of secondary clinical, process and cost-effectiveness endpoints will be collected and analysed. Analysis will be on an intention-to-treat basis. DISCUSSION: The Investigation of Palpitations in the ED (IPED) study aims to recruit 242 participants across 10 hospital sites. It will be the first study to investigate the ability of a smart phone-based event recorder to detect symptomatic cardiac rhythms compared to standard care for ED patients with palpitations and pre-syncope with no obvious cause in the ED. This smart phone event recorder will allow ED patients who have presented with palpitations or pre-syncope to record their ECG tracing if they have a further episode and may increase the rate of underlying rhythm diagnosis. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02783898 . Registered on 26 May 2016.

Hybrid long-term temporary pacing.

Prolonged temporary pacing is associated with frequent complications. We describe a patient with aortic endocarditis and acquired tri-fascicular block in whom back-up pacing was indicated. Using a Seldinger technique via a subclavian approach, a permanent active-fixation lead was positioned in the right ventricle. The lead was tunnelled subcutaneously for 6 cm, and the proximal end was connected to a standard single chamber pulse generator. The procedure was well tolerated and over a period of four months there were no complications or infection. The PR interval subsequently reduced in duration to 200 ms and as no episodes of AV block had occurred, the lead was easily removed with retraction of the helix and gentle traction.

In-hospital cardiac arrest leads to chronic memory impairment.

OBJECTIVE: To assess the prevalence and severity of memory deficits in a group of patients who survived an in-hospital cardiac arrest (IHCA) in comparison with patients resuscitated after cardiac arrest outside hospital (OHCA) and patients with acute myocardial infarction (MI). SUBJECTS: Thirty-five IHCA survivors, 35 OHCA survivors, and 35 patients who had suffered MI uncomplicated by cardiac arrest. PROCEDURE: Participants were assessed 8.2 (4.5) months after the event for current affective state (Hospital anxiety and depression scale (HADS)), pre-morbid intelligence (National adult reading test (NART)), short-term memory (digit span test) and long-term episodic memory (Rivermead behavioural memory test-RBMT). RESULTS: IHCA patients scored lower on the RBMT than MI controls but did not score significantly differently OHCA patients. Moderate or severe memory impairment was found in 26% of the IHCA group and 38% of the OHCA group. None of the MI group was found to have this degree of impairment. This difference in prevalence of memory impairment between the two cardiac arrest groups was not statistically significant. However, both arrest groups had significantly greater memory impairment than the MI control group. CONCLUSIONS: Clinically important memory impairment was found in one in four patients surviving IHCA. The shorter arrest durations that are thought to be associated with IHCA may not be sufficient to protect patients from memory impairment associated with cerebral hypoxia.

Long-term emotional consequences of in-hospital cardiac arrest and myocardial infarction.

OBJECTIVES: Prevalence rates for post-traumatic stress disorder (PTSD) of 10% have been reported following myocardial infarction (MI). However, there has been little research conducted on the long-term emotional sequelae of cardiac arrest (CA). The present study provides new information in that regard. The research aims were: (1). to compare the prevalence and severity of emotional disability in survivors of CA with that of cardiac patients who suffered an MI but no CA, (2). to assess both groups for the symptoms of PTSD, and (3). to assess the validity of a self-report measure for PTSD with a cardiac population. DESIGN: Case-control study. METHOD: Patients who suffered a cardiac arrest in-hospital (N = 27) were compared with patients who had an MI uncomplicated by cardiac arrest (N = 27), 9.6 (5.0) months following their index event. Each patient completed a series of questionnaires and a structured interview to ascertain affective adjustment, and PTSD symptoms and diagnoses. RESULTS: (1). Most MI and CA patients reported high levels of emotional well-being and stability. (2). Five (19%) CA survivors and two (7%) MI survivors (ns) fulfilled DSM-IV criteria for PTSD when assessed by structured clinical interview (SCID). (3). There was relatively poor agreement between the interview and self-report diagnoses when identifying PTSD cases (kappa =.39). CONCLUSION: The significant minority of cardiac patients warranting diagnoses of PTSD has implications for their management and rehabilitation. Identification of these patients is an important step towards improving their overall health outcomes. The structured clinical interview remains the 'gold standard' for the identification of PTSD in cardiac patient populations.

Solving the puzzle of strong French coffee, palpitation and dizziness.

A 38-year-old gentleman presented to the emergency department at the University Hospital in Geneva with nausea, rapid palpitation and presyncope. This was followed by a poor night's sleep, a day of strenuous walking in the city and drinking a large quantity of strong French coffee. 12-lead ECG revealed tachycardia with slightly increased QRS duration of right bundle branch block pattern and left axis deviation. Without the electrophysiological (EP) study, the patient was diagnosed with supraventricular tachycardia. On return to Edinburgh, he was investigated under the EP study, which confirmed fascicular tachycardia, a rare and uncommon presentation of ventricular tachycardia. The patient was successfully treated with radiofrequency catheter ablation therapy, which is curative in over 80% of the cases. This case highlights the importance of referring patients with repeatedly presenting arrhythmic episodes to undergo EP study. This will avoid putting them at unnecessary future risk, while offering the opportunity to definitely diagnose and provide curative therapy.

Type D personality and three-month psychosocial outcomes among patients post-myocardial infarction.

OBJECTIVE: Type D personality has been proposed as a risk factor for poor prognosis in cardiac patients. Recent studies which have adopted a dimensional approach to Type D (negative affectivity×social inhibition) found no effect of Type D on mortality, after controlling for its constituent elements. To-date, no study has determined if Type D is associated with psychosocial outcomes in post-myocardial infarction (MI) patients when conceptualised as a dimensional variable. METHODS: Participants were 192 MI patients (138 males, 54 females, mean age 66.0years) who provided demographic and clinical information, and completed measures of Type D one-week post-MI. Three months later, 131 of these MI patients completed measures of disability and quality of life. RESULTS: Using regression analyses, adjusted for demographic and clinical data, Type D emerged as a significant predictor of disability and quality of life in MI patients, when analysed using the traditional categorical approach. However, Type D did not predict disability and quality of life when it was analysed using the interaction of negative affectivity and social inhibition. Negative affect emerged as a significant predictor of both disability (ß=.433, t(130)=3.53, p<.01), and quality of life (ß=-.624, t(130)=-5.68, p<.001). CONCLUSIONS: The results suggest that Type D is not associated with short-term psychosocial outcome in MI patients, after controlling for its constituent elements. However, negative affect was significantly associated with both disability and quality of life. Future research should conceptualise Type D as the interaction between negative affectivity and social inhibition, rather than as a typology.

Type D personality predicts poor medication adherence in myocardial infarction patients.

Type D personality, the combination of negative affectivity (NA) and social inhibition (SI), is an emerging risk factor in cardiovascular disease. This study aimed to examine one possible behavioural mechanism to explain the link between Type D and ill-health. It was hypothesised that Type D personality would predict medication adherence in myocardial infarction (MI) patients. In a prospective study, 192 MI patients (54 females and 138 males) completed measures of Type D personality and provided demographic and medical information 1 week post-MI, and then 131 patients went on to complete a self-report measure of medication adherence 3 months post-MI. It was found that Type D personality predicts adherence to medication, after controlling for demographic and clinical risk factors. Critically, the constituent components of Type D, NA and SI, interact to predict medication adherence, after controlling for the effects of each component separately. Poor adherence to medication may represent one mechanism to explain why Type D cardiac patients experience poor clinical outcome, in comparison to non-Type D patients. Interventions, which target the self-management of medication, may be useful in these high-risk patients.

Type D personality and illness perceptions in myocardial infarction patients.

OBJECTIVES: To determine the relationship between Type D personality (the tendency to experience negative emotions and to be socially inhibited) and illness beliefs in postmyocardial infarction (MI) patients. METHODS: One hundred and ninety-two MI patients participated. Patients were assessed on demographic variables and completed the Type D Scale (DS14) and Brief Illness Perceptions Questionnaire one week post-MI. RESULTS: Multivariate analysis of variance revealed that Type D patients were significantly different from non-Type D patients on every illness perception dimension. Type D patients believe that their illness has significantly more serious consequences (P<.001), will last significantly longer (P<.001), will be significantly less controllable by them (P<.05) or through treatment (P<.001) compared to non-Type D patients, and experience significantly more symptoms that they attribute to their illness (P<.001). In addition, they are significantly more concerned about their illness (P<.05), experience significantly more emotions as a result (P<.001), and find their illness to be significantly less comprehensible compared to non-Type D individuals (P<.001). CONCLUSION: Type D individuals possess a distinct profile of illness beliefs, which may help explain the adverse effect of Type D on health outcomes following MI. Future research should evaluate intervention strategies to tackle illness perceptions in these high-risk patients.

T-wave alternans found in preventricular tachyarrhythmias in CCU patients using a wavelet transform-based methodology.

Ventricular tachyarrhythmias are potentially lethal cardiac pathologies and the commonest cause of sudden cardiac death. Efforts to predict the onset of such events are based on feature extraction from the surface ECG. T-wave alternans (TWAs) are considered a marker of abnormal ventricular function that may be associated with ventricular tachycardia (VT) and ventricular fibrillation. A novel TWA detection algorithm utilizing the continuous wavelet transform is described in this paper. Simulated ECGs containing artificial TWA were used to test the algorithm that achieved a sensitivity of 91.40% and a specificity of 94.00%. The algorithm was subsequently used to analyze the ECGs of eight patients prior to the onset of VT. Of these, the algorithm indicated that five patients exhibited TWA prior to the onset of the tachyarrhythmic events, while the remaining three patients did not exhibit identifiable TWA. Healthy individuals were also studied in which one short TWA episode was detected by the algorithm. However, closer visual inspection of the data revealed this to be a likely false positive result.

Prediction of cognitive dysfunction after resuscitation from out-of-hospital cardiac arrest using serum neuron-specific enolase and protein S-100.

BACKGROUND: More than 50% of patients initially resuscitated from out-of-hospital cardiac arrest die in hospital. OBJECTIVE: To investigate the prognostic value of serum protein S-100 and neuron-specific enolase (NSE) concentrations for predicting (a) memory impairment at discharge; (b) in-hospital death, after resuscitation from out-of-hospital cardiac arrest. METHODS: In a prospective study of 143 consecutive survivors of out-of-hospital cardiac arrest, serum samples were obtained within 12, 24-48 and 72-96 hours after the event. S-100 and NSE concentrations were measured. Pre-discharge cognitive assessment of patients (n = 49) was obtained by the Rivermead Behavioural Memory Test (RBMT). The relationship between biochemical brain marker concentrations and RBMT scores, and between marker concentrations and the risk of in-hospital death was examined. RESULTS: A moderate negative relationship was found between S-100 concentration and memory test score, at all time points. The relationship between NSE and memory test scores was weaker. An S-100 concentration >0.29 microg/l at time B predicted moderate to severe memory impairment with absolute specificity (42.8% sensitivity). S-100 remained an independent predictor of memory function after adjustment for clinical variables and cardiac arrest timing indices. NSE and S-100 concentrations were greater in patients who died than in those who survived, at all time points. Both NSE and S-100 remained predictors of in-hospital death after adjustment for clinical variables and cardiac arrest timing indices. The threshold concentrations yielding 100% specificity for in-hospital death were S-100: 1.20 microg/l (sensitivity 44.8%); NSE 71.0 microg/l (sensitivity 14.0%). CONCLUSIONS: Estimation of serum S-100 concentration after out-of-hospital cardiac arrest can be used to identify patients at risk of significant cognitive impairment at discharge. Serum S-100 and NSE concentrations measured 24-48 hours after cardiac arrest provide useful additional information.

A fully automated algorithm for the determination of respiratory rate from the photoplethysmogram.

OBJECTIVE: To determine if an automatic algorithm using wavelet analysis techniques can be used to reliably determine respiratory rate from the photoplethysmogram (PPG). METHODS: Photoplethysmograms were obtained from 12 spontaneously breathing healthy adult volunteers. Three related wavelet transforms were automatically polled to obtain a measure of respiratory rate. This was compared with a secondary timing signal obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. In addition, individual breaths were resolved using the wavelet-method to identify the source of any discrepancies. RESULTS: Volunteer respiratory rates varied from 6.56 to 18.89 breaths per minute. Through training of the algorithm it was possible to determine a respiratory rate for all 12 traces acquired during the study. The maximum error between the PPG derived rates and the manually determined rate was found to be 7.9%. CONCLUSION: Our technique allows the accurate measurement of respiratory rate from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.

Biventricular vs. left univentricular pacing in heart failure: rationale, design, and endpoints of the B-LEFT HF study.

AIMS: Cardiac resynchronization therapy (CRT) confers sustained therapeutic benefits to patients suffering from congestive heart failure (CHF) due to systolic dysfunction associated with ventricular dyssynchrony. Biventricular (BiV) pacing has, thus far, been the preferred method, as it corrects both electrical and mechanical dyssynchrony. Left ventricular (LV) only pacing, which has conferred similar benefits in pilot studies, may be an alternative treatment method. 'Biventricular vs. left univentricular pacing with ICD back-up in heart failure patients' (B-LEFT HF) is an international, prospective, randomized, parallel-design, double-blind, clinical trial to examine whether LV only pacing is as safe and effective as BiV pacing in patients suffering from CHF. METHODS AND RESULTS: The trial will randomly assign 172 patients to either LV only or BiV pacing. The study has prospectively defined efficacy endpoints to be evaluated at 6 months, which are (i) changes in functional capacity and degree of reverse remodelling (primary) and (ii) changes in the heart failure clinical composite response (secondary). CONCLUSION: Because LV only pacing in CRT is likely to be technically less challenging and costly than BiV, a specifically designed study is needed to compare the safety and effectiveness of the two configurations. B-LEFT HF has been designed to settle this critical issue.