The normal electrocardiogram

Conduction system pacing using electro-anatomical mapping-guided system vs. fluoroscopy: a systematic review, meta-analysis and economic evaluation

Introduction

Electro-anatomical mapping (EAM) system has been shown as an alternative procedure to fluoroscopy for conduction system pacing (CSP) in patients with severe bradyarrhythmia, however its beneficial and harmful effects has not been assessed in a systematic review (SR). We sought to assess their safety, effectiveness and cost-effectiveness.

Methods

A SR of the available scientific literature was conducted on the safety, effectiveness, and cost-effectiveness of CSP using EAM system versus fluoroscopy in patients with severe bradyarrhythmia. A partial economic evaluation was carried out to compare the costs of both strategies from the perspective of the Spanish National Health System. A budget impact analysis was also conducted with a five-year horizon.

Results

Seven comparative observational studies (N = 231), analyzing the use of EAM versus fluoroscopy were selected. Statistically significant differences were observed in total fluoroscopy time: -9.87 minutes (95%CI:-14.20, -5.53, p < 0.01; I 2 = 95%; k = 7; n = 231); His-lead fluoroscopic time: -8.08 minutes (95%CI:-10.36, -5.81, p < 0.01; I 2 = 0%; k = 2; n = 50); and His-lead radiation dose: -17.21 mGy (95%CI:-24.08, -10.34, p < 0.01; k = 1; n = 20). No differences in total fluoroscopy dose, successful procedure or safety were found. The use of EAM represents an increase of EUR 1397.81 per patient and a net budget impact of EUR 1.63 million.

Discussion

EAM is a valuable alternative for patients who should not be exposed to ionizing radiation with similar effectiveness and safety than fluoroscopy. However, the inclusion of EAM systems, for the indication under study, in routine clinical practice would mean an increase in costs for the Spanish National Health System.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=421072, identifier (CRD42023421072).

Incidence of Coronary Artery Disease After Permanent Pacemaker Implantation: A Hospital-based Study from East India

Bradyarrhythmias, characterized by heart rates of <60 bpm due to conduction issues, carry risks of sudden cardiac death and falls. Pacemaker implantation is a standard treatment, but the interplay between bradyarrhythmias, coronary artery disease (CAD), and patient attributes requires further exploration. This study was a retrospective hospital record-based study that analyzed data from 699 patients who underwent pacemaker implantation for symptomatic bradyarrhythmias between February 2019 and February 2022. Clinical parameters, coronary angiography (CAG) findings, ejection fraction, and indications for pacemaker implantation were documented. The relationship between CAD severity, specific bradyarrhythmias, and ejection fraction was explored. Statistical analysis included chi-squared tests and t tests. The mean age of the study population (n = 699) was 66.75 years (male:female ratio, 70:30), with 77.2% having type 2 diabetes and 61.6% being hypertensive. The majority of patients had minor or non-obstructive CAD (61.8%), followed by normal CAG findings (25.75%) and obstructive CAD (12.45%). Complete heart block (CHB) was the primary indication for pacemaker implantation (55.2%), followed by sick sinus syndrome (22.3%). The results did not show any association between ejection fraction and CAG findings. Patients who presented with CHB had a higher incidence of obstructive CAD, indicating greater severity. This study sheds light on the intricate interplay between severe bradyarrhythmias, CAD, and patient characteristics. Our analysis revealed no statistical significance between obstructive CAD and the need for a permanent pacemaker. This makes us question our practice of maintaining a low threshold for coronary angiography during pacemaker implantation. The observed low yield and anticoagulation protocol reassure us of the choice to delay this diagnostic intervention. These insights can guide tailored management strategies, enhancing clinical care approaches for patients with severe bradyarrhythmias necessitating pacemaker implantation.

Pig-to-human heart xenotransplantation in two recently deceased human recipients

Genetically modified xenografts are one of the most promising solutions to the discrepancy between the numbers of available human organs for transplantation and potential recipients. To date, a porcine heart has been implanted into only one human recipient. Here, using 10-gene-edited pigs, we transplanted porcine hearts into two brain-dead human recipients and monitored xenograft function, hemodynamics and systemic responses over the course of 66 hours. Although both xenografts demonstrated excellent cardiac function immediately after transplantation and continued to function for the duration of the study, cardiac function declined postoperatively in one case, attributed to a size mismatch between the donor pig and the recipient. For both hearts, we confirmed transgene expression and found no evidence of cellular or antibody-mediated rejection, as assessed using histology, flow cytometry and a cytotoxic crossmatch assay. Moreover, we found no evidence of zoonotic transmission from the donor pigs to the human recipients. While substantial additional work will be needed to advance this technology to human trials, these results indicate that pig-to-human heart xenotransplantation can be performed successfully without hyperacute rejection or zoonosis.

A higher resting heart rate is associated with cardiovascular event risk in patients with type 2 diabetes mellitus without known cardiovascular disease

A higher resting heart rate (RHR) is associated with an increased risk of cardiovascular events in patients with type 2 diabetes mellitus (T2DM) and cardiovascular diseases. The aim of this study was to investigate the association between RHR and cardiovascular events in T2DM patients with diabetic retinopathy and without known cardiovascular disease. We analyzed the association between RHR and cardiovascular events, including coronary, cerebral, renal and vascular events or cardiovascular death in T2DM patients with retinopathy and hyperlipidemia without prior cardiovascular events who were enrolled in the EMPATHY study. Data from 4746 patients were analyzed. The median RHR was 76 bpm. Patients were divided into four groups based on their baseline RHR ( < 60, 60-69, 70-79, and ≥80 bpm). Patients with a higher RHR were more likely to be younger and had a higher body mass index, blood pressure value, HbA1c value, and estimated glomerular filtration rate and a lower B-type natriuretic peptide value; they also had a higher proportion of current smoking status, neuropathy, and nephropathy. After adjusting for confounders, including the aforementioned risk factors, a RHR of 70-79 bpm and a RHR ≥ 80 bpm were significantly associated with cardiovascular events (hazard ratio 1.50, 95% CI 1.03-2.20; and hazard ratio 1.62, 95% CI 1.11-2.36; respectively) compared to a RHR of 60-69 bpm. The analysis using restricted cubic splines indicated that the cardiovascular risk seemed to be similarly high when the RHR range was ≥70 bpm. In conclusion, in T2DM patients with diabetic retinopathy and without known cardiovascular disease, a high RHR, particularly ≥70 bpm, was associated with the risk of cardiovascular events compared to a RHR of 60-69 bpm. High resting heart rate (RHR), particularly ≥70 bpm, was associated with the risk of cardiovascular events compared to RHR 60-69 bpm in patients with type 2 diabetes mellitus (T2DM), diabetic retinopathy, and hyperlipidemia, but without known cardiovascular disease.

In-Hospital ECG Findings, Changes in Medical Management, and Cardiovascular Outcomes in Patients With Acute Stroke or Transient Ischemic Attack

Background In patients with acute ischemic stroke, little is known regarding the frequency of abnormal ECG findings other than atrial fibrillation and their association with cardiovascular outcomes. We aim to analyze the frequency and type of abnormal ECG findings, subsequent changes in medical treatment, and their association with cardiovascular outcomes in patients with acute ischemic stroke. Methods and Results In the investigator-initiated multicenter MonDAFIS (impact of standardized monitoring for detection of atrial fibrillation in ischemic stroke) study, 3465 patients with acute ischemic stroke or transient ischemic attack and without known atrial fibrillation were randomized 1:1 to receive Holter-ECG for up to 7 days in-hospital with systematic evaluation in a core cardiology laboratory (intervention group) or standard diagnostic care (control group). Outcomes included predefined abnormal ECG findings (eg, pauses, atrial fibrillation, brady-/tachycardias), medical management in the intervention group, and combined vascular end point (recurrent stroke, myocardial infarction, major bleeds, or all-cause death) and mortality at 24 months in both randomization groups. Predefined abnormal ECG findings were detected in 326 of 1693 (19.3%) patients in the intervention group. Twenty of these 326 patients (6.1%) received a pacemaker, and 62 of 326 (19.0%) patients had newly initiated or discontinued β-blocker medication. Discontinuation of β-blockers was associated with a higher death rate in the control group than in the intervention group during 24 months after enrollment (adjusted hazard ratio, 11.0 [95% CI, 2.4-50.4]; P=0.025 for interaction). Conclusions Systematic in-hospital Holter ECG reveals abnormal findings in 1 of 5 patients with acute stroke, and mortality was lower at 24 months in patients with systematic ECG recording in the hospital. Further studies are needed to determine the potential impact of medical management of abnormal ECG findings. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02204267.

The ΔWaveECG: The differences to the normal 12‑lead ECG amplitudes

BACKGROUND

The QRS, ST segment, and T-wave waveforms of electrocardiogram are difficult to interpret, especially for non-ECG experts readers, like general practitioners. As the ECG waveforms are influenced by many factors, like body build, age, sex, electrode placement, even for experience ECG readers the waveform is difficult to interpret. In this research we have created a novel method to distinguish normal from abnormal ECG waveforms for an individual ECG based on the ECG amplitude distribution derived from normal standard 12‑lead ECG recordings.

AIM

Creation of a normal ECG amplitude distribution to enable the distinction by non-ECG experts of normal from abnormal waveforms of the standard 12‑lead ECG.

METHODS

The ECGs of healthy normal controls in the PTB-XL database were used to construct a normal amplitude distribution of the 12 lead ECG for males and females. All ECGs were resampled to have the same number of samples to enable the classification of an individual ECG as either normal or abnormal, i.e. within the normal amplitude distribution or outside, the ΔWaveECG.

RESULTS

From the same PTB-XL database six ECG's were selected, normal, left and right bundle branch block, and three with a myocardial infarction. The normal ECG was obviously within the normal distribution, and all other five showed clear abnormal ECG amplitudes outside the normal distribution in any of the ECG segments (QRS, ST segment and remaining STT segment).

CONCLUSION

The ΔWaveECG can distinguish the abnormal from normal ECG waveform segments, making the ECG easier to classify as normal or abnormal. Conduction disorders and ST changes due to ischemia and abnormal T-waves are effortless to detect, also by non-ECG expert readers, thus improving the early detection of cardiac patients.

Sinus Tachycardia: a Multidisciplinary Expert Focused Review

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

A novel automated junctional ectopic tachycardia detection tool for children with congenital heart disease

Background

Junctional ectopic tachycardia (JET) is a prevalent life-threatening arrhythmia in children with congenital heart disease (CHD), with marked resemblance to normal sinus rhythm (NSR) often leading to delay in diagnosis.

Objective

To develop a novel automated arrhythmia detection tool to identify JET.

Methods

A single-center retrospective cohort study of children with CHD was performed. Electrocardiographic (ECG) data produced by bedside monitors is captured automatically by the Sickbay platform. Based on the detection of R and P wave peaks, 2 interpretable ECG features are calculated: P prominence median and PR interval interquartile range (IQR). These features are used as input to a simple logistic regression classification model built to distinguish JET from NSR.

Results

This study analyzed a total of 64.5 physician-labeled hours consisting of 509,833 cardiac cycles (R-R intervals), from 40 patients with CHD. The extracted P prominence median feature is much smaller in JET compared to NSR, whereas the PR interval IQR feature is larger in JET compared to NSR. The area under the receiver operating characteristic curve for the unseen patient test cohort was 93%. Selecting a threshold of 0.73 results in a true-positive rate of 90% and a false-positive rate of 17%.

Conclusion

This novel arrhythmia detection tool identifies JET, using 2 distinctive features of JET in ECG-the loss of a normal P wave and PR relationship-allowing for early detection and timely intervention.

A Teenager Physical Fitness Evaluation Model Based on 1D-CNN with LSTM and Wearable Running PPG Recordings

People attach greater importance to the physical health of teenagers because adolescence is a critical period for the healthy development of the human body. With the progress of biosensing technologies and artificial intelligence, it is feasible to apply wearable devices to continuously record teenagers’ physiological signals and make analyses based on modern advanced methods. To solve the challenge that traditional methods of monitoring teenagers’ physical fitness lack accurate computational models and in-depth data analyses, we propose a novel evaluation model for predicting the physical fitness of teenagers. First, we collected 1024 teenagers’ PPGs under the guidance of the proposed three-stage running paradigm. Next, we applied the median filter and wavelet transform to denoise the original signals and obtain HR and SpO₂. Then, we used the Pearson correlation coefficient method to finalize the feature set, based on the extracted nine physical features. Finally, we built a 1D-CNN with LSTM model to classify teenagers’ physical fitness condition into four levels: excellent, good, medium, and poor, with an accuracy of 98.27% for boys’ physical fitness prediction, and 99.26% for girls’ physical fitness prediction. The experimental results provide evidence supporting the feasibility of predicting teenagers’ physical fitness levels by their running PPG recordings.

Physiological responses, self-reported health effects, and cognitive performance during exposure to carbon dioxide at 20 000 ppm

In this study, 24 subjects (20-58 years) were exposed to carbon dioxide (CO₂ ) at 770 ppm and 20 000 ppm in an exposure laboratory for 4-h, including 2 × 15 min of cycling to investigate the effects on acid-base balance, physiological responses, cognitive performance and acute health. Capillary blood analysis, heart rate, respiratory rate, divided attention, flexibility, and sustained attention from the Test Battery for Attentional Performance (TAP), critical flicker fusion frequency (CFF), and self-reported symptoms were measured before, during, and after the 4-h exposure. Blood pH decreased and partial pressure of carbon dioxide (pCO₂ ) increased significantly when exposed to 20 000 ppm CO₂ compared to 770 ppm. However, the values remained within the normal range. In addition, respiratory rate increased slightly but significantly at 20 000 ppm CO₂ . No significant changes in heart rate, CFF, task performance or acute health were found. In sum, the findings suggest that the observed changes in acid-base balance and ventilation can be classified as physiological adaptation responses. Impairment of cognitive performance is not expected from exposure to 20 000 ppm CO₂ , neither as direct effect on central nervous system function nor as a distraction related to perception of health effects.

Effects of the Spatial Structure Conditions of Urban Underpass Tunnels' Longitudinal Section on Drivers' Physiological and Behavioral Comfort

To investigate the physiological and behavioral comfort of drivers traversing urban underpass tunnels with various spatial structure conditions, a driving simulator experiment was conducted using 3DMAX and SCANeRTM studio software. Three parameters, including the slope, slope length, and height of a tunnel, were selected as research objects to explore the optimal combination of structural parameters in urban underpass tunnels. The heart rate (HR), interbeat (RR) interval, speed, and lane centerline offset value were collected for 30 drivers. Then, a measurement model of the relationship among HR, RR interval, speed, lane centerline offset value, and structural parameters was established by using partial correlation analyses and the stepwise regression method. On this basis, a structural constraint model based on the drivers’ physiological and behavioral comfort thresholds was also constructed. The results show that the driver’s HR, RR interval, speed, and lane centerline offsets are significantly related to the tunnel height, slope, and slope length. More importantly, this paper not only analyzed the effects of various structural parameters on drivers’ physiology and behavior but also proposed an optimized combination of structural parameters based on drivers’ physiological and behavioral comfort. It can reasonably improve tunnel design in China, ensure tunnel traffic safety, and seek the maximum comfort of the driver in the driving process.

Preparticipation Cardiac Evaluation Findings in a Cohort of Collegiate Female Athletes

Knowledge of cardiovascular adaptations in athletes has predominantly focused on males, with limited data available on females who compromise a substantial percentage of all collegiate athletes. A multicenter retrospective cohort review of preparticipation cardiovascular screening data of 329 National Collegiate Athletic Association Division I female athletes was performed. This included physical exams, electrocardiograms, and echocardiograms. Female athletes in class IB sports had elevated systolic blood pressure (p = 0.01). For electrocardiograms, 7 (2%) had abnormal findings: 100% were white; 6 of 7 (86%) participated in IIC sports. Black athletes had longer PR intervals (p ≤ 0.001), whereas white athletes had longer QTc and QRS durations (p = 0.02 and 0.01, respectively). Athletes in IC and IIC sports had longer QTc intervals (p = 0.01). For echocardiographic parameters, no differences were noted based on race. However, significant differences were noted based on classification of sport: athletes in class IC sports had higher left-atrial volume indexes and E/A ratios. Athletes in class IB and IIC had increased left-ventricular wall thicknesses and aortic root dimensions. In conclusion, among one of the largest cohorts of collegiate female athlete preparticipation cardiac screening data to date, significant differences in various parameters based on classification of sport and race were observed. These categorizations should be considered when interpreting cardiovascular screening in female collegiate athletes to improve screening and guide future research.

[Acute bradycardia]

Clinical relevance of acute bradycardia is driven by symptoms and not primarily by the reported decreased heart rate. Bradycardias may remain asymptomatic especially due to compensatory mechanisms (in particular increase of left ventricular ejection fraction). Nearly half of acute bradycardias have a reversible cause. Detection of potential reversible bradycardia causes is therefore regarded as the cornerstone of bradycardia treatment in the emergency setting. Effective therapies for the treatment of acute bradycardia are available, including intravenous chronotropic drugs and pacemaker implantation.

Pericardial effusions in adolescent girls with anorexia nervosa: clinical course and risk factors

The aim of this study was to evaluate cardiac, biochemical and endocrine differences between female adolescents with anorexia nervosa (AN) with and without pericardial effusions. We studied 128 female adolescents (9.8-17.7 years) with anorexia nervosa (AN) diagnosed according to DSM-IV (American Psychiatric Association, 1994) criteria. They all underwent an echocardiographic evaluation. In 29 patients (22.2 %) a pericardial effusion (ranging between >or= 0.35-2.5 cm) was noted. None of the patients were clinically symptomatic. After 3 months of refeeding, the effusions disappeared in 18/29 patients while in 7/29 patients a pericardial effusion > 0.3 cm persisted. Risk factors for development of effusions were a BMI <or= 13,5 kg/m(2), weight loss >or= 25% and IGF-1-level <or=100 ng/ml. Pericardial effusions are common in adolescent AN patients. They are mostly asymptomatic not requiring any intervention and spontaneously regress with refeeding. They are more common in the patients with the most significant weight loss.

Increased mortality rates of young children with traumatic injuries at a US army combat support hospital in Baghdad, Iraq, 2004

OBJECTIVE

The objective of this study was to determine whether age <or=8 y is an independent predictor of mortality in noncoalition trauma patients at a US combat support hospital.

METHODS

A retrospective chart review was conducted of 1132 noncoalition trauma patients who were admitted to a combat support hospital between December 2003 and December 2004. Data on age, severity of injury indices, and in-hospital mortality rates were analyzed. All variables that were associated with death on univariate analysis were analyzed by multivariate logistic regression to determine independent associations with mortality.

RESULTS

There were 38 young pediatric patients (aged <or=8 years) and 1094 older pediatric and adult patients (aged >8 years). Penetrating trauma accounted for 83% of all injuries. Young pediatric patients compared with older pediatric and adult patients had increased severity of injury indicated by decreased Glasgow Coma Scale score; increased incidence of hypotension, base deficit, and serum pH on admission; red blood cell transfusion amount; and increased injury severity scores on admission. Young pediatric patients compared with older pediatric and adult patients also had increased ICU lengths of stay (median 2 [interquartile range 0-5] vs median 0 [interquartile range 0-2] days) and in-hospital mortality rate (18% vs 4%), respectively. Multivariate logistic regression indicated that base deficit, injury severity score of >or=15, Glasgow Coma Scale score of <or=8, and age of <or=8 years were independently associated with mortality.

CONCLUSIONS

Young children who present to a combat support hospital have increased severity of injury compared with older children and adults. In a population with primarily penetrating injuries, after adjustment for severity of injury, young children may also have an independent increased risk for death compared with older children and adults. Providing forward-deployed medical staff with pediatric-specific equipment and training in the acute care of young children with severe traumatic injuries may improve outcomes in this population.

Features of an exceptionally narrow QRS data set

BACKGROUND

Little attention has been directed to the characteristics of electrocardiograms (ECGs) with brief QRS durations (BD).

METHODS

From a database of 859,977 computer-analyzed (Marquette 12SL, GE Healthcare, Milwaukee, WI, USA) ECGs of 216,148 patients, 1805 patients (data set of BD: 19,718 ECGs; age, >18 years, unpaced), had, in at least one ECG, a QRS duration of less than 62 milliseconds, a prevalence of 0.8%.

RESULTS

The QRS duration ranged from 46 to 188 milliseconds; values fluctuated between excessive brevity and the traditionally normal (80-95 milliseconds), with many values in the 60's. The average age at first acquisition was 56 years (range, 18-96 years); 1371 were female (76%) and 433 were males (24%); and 416 were white (23%), 1243 African American (69%), 109 other (6%). The summed 12-lead QRS amplitude (SigmaQRS) ranged from 2800 to 32,929 microV (mean +/- SD, 11,154 +/- 4101), and heart rate ranged from 40 to 269 (98 +/- 26). There was a statistically positive relationship between QRS duration (in the range 52-105 milliseconds) and SigmaQRS (P < 0001): for each 1000 microV increment, duration increased by 0.7 milliseconds (95% confidence interval [CI], 0.66-0.73 milliseconds). Conversely, for each 5-millisecond increment in duration, SigmaQRS increased by 475 microV (95% CI, 450-498 microV). There was an inverse relationship between QRS duration and heart rate (P < .0001): for every 10 beat rate increase, the duration dropped by 1.14 milliseconds (95% CI, 1.09-1.19 milliseconds). An additional data set of normal QRS durations ND consisted of 2902 subjects, none of whose 40,327 ECGs showed a QRS duration less than 62 milliseconds; 2.8% of ND ECGs had durations in the 62-69 millisecond range, 26% in BD. Sinus tachycardia was 43% in BD and 24% in ND. The average age of ND was 58 years (range, 18-100 years); 44% were male and 56% female; and 39% were white and 57% were African American. A positive relationship between duration and amplitude was found among ND subjects as well: for each 1000 point increase in SigmaQRS, duration increased by 0.45 milliseconds (P < .0001; 95% CI, 0.42-0.47 milliseconds). The duration amplitude relationship did not hold for durations greater than 105 milliseconds in either data set.

CONCLUSION

Over the full extended span of QRS durations (46-106 milliseconds), the value of the latter is directly related to the total summed amplitude of the 12-lead QRS. An inverse relationship is demonstrable with heart rate.

Examination of print and telephone channels for physical activity promotion: Rationale, design, and baseline data from Project STRIDE

BACKGROUND

Project STRIDE is a 4-year randomized controlled trial comparing two computer-based expert system guided intervention delivery channels (phone vs. print) for physical activity adoption and short-term maintenance among previously sedentary adults.

METHODS

Sedentary adults (n=239) were randomized to one of the following (1) telephone-based, individualized motivationally-tailored feedback; (2) print-based, individualized motivationally-tailored feedback; (3) contact-control delayed treatment group (received intervention after 12 months as control). This paper: (1) outlines the study design, rationale, and participant sample; and (2) describes relationships between baseline variables to better understand their influence on the efficacy of the intervention.

RESULTS

Participants averaged 19.8+/-25.0 min of physical activity/week that was at least of moderate intensity, with no group differences. The average estimated VO(2) at 85% of maximum heart rate was 25.6 ml/kg/min. Body fat was 34.1% for women and 23.2% for men and the BMI of the sample averaged 28.5 kg/m(2).

CONCLUSIONS

Project STRIDE examines non face-to-face approaches for promoting physical activity behavior. It has unique features including a direct comparison of an expert system guided intervention delivered via phone or print. Future analyses will examine the cost-effectiveness of the interventions and this will likely yield important information for policy-makers.

Can we improve cardiovascular risk prediction beyond risk equations in the physician's office?

BACKGROUND AND OBJECTIVES

Beyond a global estimation of the cardiovascular risk through the assessment of major risk factors and their integration in dedicated risk scales or equations, the use of specific markers provides additive prognostic information at an individual level, including predisposing factors, which are not included in the risk equations as well as the individual susceptibility to their long-term exposure. However, the majority of these markers require specific devices and skills, which are not widely available in primary care.

METHODS

Some clinical and/or "low-cost" parameters are shown to be valuable risk markers, and their use could refine the risk estimation in a physician's office. Several epidemiologic studies suggest the heart rate, the pulse pressure and the ankle-brachial index are effective cardiovascular risk markers. The arms systolic pressure asymmetry could also be a useful marker of risk.

RESULTS AND CONCLUSIONS

Through a general review, the authors evaluate the potential of these clinical markers, including their use in combination for more accurate risk determination.

Sinus tachyarrhythmias and the specific bradycardic agents: a marriage made in heaven?

A relatively novel group of drugs that inhibit the funny current in the sinus node pacemaker cells, the so-called specific bradycardic agents, are likely to play a significant role in the management of a wide range of cardiovascular disorders, including the sinus tachyarrhythmias. This comprehensive review initially provides an insight into these agents, their historical background, and their mechanism of action. It then discusses the differential diagnosis of the sinus tachyarrhythmias (normal sinus tachycardia, inappropriate sinus tachycardia, postural orthostatic tachycardia syndrome, and sinus node reentry tachycardia), elaborates on their pathophysiologic basis, and provides up-to-date evidence-based information on their optimum management. The specific bradycardic agents, by the very nature of their mode of action, may prove ideal therapies for the management of the sinus tachyarrhythmias, and this is explored at every stage.

Results of surgery for congenital pulmonary stenosis; comparison of the transventricular and transarterial approaches

Clinical and physiologic data before and after operation are presented in 2.5 patients who underwent surgical correction of congenital pulmonary stenosis with intact ventricular septum. Sixteen patients were operated on by the transventricular approach, 7 by the transarterial route, and 2 had infundibulectomies. Postoperative changes in the clinical status, phonocardiogram, electrocardiogram, x-rays, and right heart catheterization values are discussed. Comparison is made of the 2 major operative technics both in the present group and in cases gathered from a review of the literature.

Arrhythmogenic right ventricular cardiomyopathy in young versus adult patients: similarities and differences

OBJECTIVES

This study was designed to evaluate and compare the patterns of arrhythmogenic right ventricular cardiomyopathy in young people and adults.

BACKGROUND

Few data are available on this cardiomyopathy in young people because clinical and morphologic findings considered pathognomonic are normally based on observations in adults. However, a familial occurrence with a probable genetic transmission led to the study of children and to early detection of this disease, in which sudden death has been reported even in young people.

METHODS

Seventeen young patients with arrhythmogenic right ventricular cardiomyopathy diagnosed at a mean age +/- SD of 14.9 +/- 4.9 years were studied. Clinical, electrocardiographic, echocardiographic, cineangiographic and biopsy findings were compared with those of 19 adult patients whose condition was diagnosed at a mean age of 38.1 +/- 13.4 years.

RESULTS

Syncope occurred in 23.5% of the young patients but in none of the adults (odds ratio of familial sudden death 5.54, p = 0.1). Ventricular couplets (odds ratio 16.0, p = 0.004) and subtricuspid bulging on echocardiography (odds ratio 5.95, p = 0.036) were prevalent in the young group. Cineangiographic data in the two groups were similar, except that more hypokinetic areas were found in adults (odds ratio 4.44, p = 0.05). Morphometric analysis of biopsy sections showed a greater amount of fibrous tissue in the young patients (p = 0.04) and a prevalence of fatty tissue in the adults (odds ratio 12, p = 0.005). During an equivalent follow-up time (mean 7 years), two young patients died suddenly, and two had ventricular fibrillation in the absence of antiarrhythmic therapy.

CONCLUSIONS

The pathognomonic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in adults are also valid for young people. Sudden or aborted death occurred frequently in young untreated patients.

The effect of left atrial histology and dimension on P wave morphology

This study correlates left atrial appendage cell size, atrial fibrosis and echocardiographic (echo) measurement of left atrial size with P wave morphology. Twelve patients with known mitral valve disease had echo measurements of left atrial size with P wave morphology. Twelve patients with known mitral valve disease had echo measurements of left atrial size prior to mitral valve surgery; patients had varying degrees of left atrial enlargement. The left atrial appendage, removed at the time of surgery, was stereologically assessed for percent fibrosis and the diameters of 50 cells were measured and averaged. These factors were correlated with P wave amplitude and duration in lead II, greatest length in any led, PR segment (end of P wave to onset of QRS), P to PR segment ratio (in lead II) and the PR interval. There was a good correlation of left atrial cell diameter with P wave amplitude (r = .69, p = 0.01). There was a good inverse correlation of percent fibrosis with the PR segment (r = -.72, p = 0.01) and a direct correlation of fibrosis with the ratio of P wave length to PR segment (r = .67 p = 0.01). There was a trend for percent fibrosis to correlate with PO wave duration but not height. No correlation was noted for any of the P wave characteristics and left atrial size. This study demonstrates that there is a correlation of P wave height with cell diameter and P wave length and PR segment with fibrosis. These data are helpful in understanding the electrocardiographic P wave.

"Acute" granulomatous pericarditis. clinical and hemodynamic correlate

Ten cases of acute constrictive pericarditis from southern Iran are presented. They differed from chronic constrictive pericarditis by the absence of ascutes and edema of the lower extremities, the presence of cardiomegaly on posteroanterior chest x-ray film, the lack of calcification of the pericardium on fluoroscopic examination, and the presence of sinus rhythm in all cases. If tuberculosis is the etiologic agent, early pericardiectomy should be considered. This is especially important in areas where close follow-up of patients is difficult or impossible, since all patients in this series ultimately developed clinically significant constriction.

Computer characterization of sinus rhythm

Sinus rhythm tracings, including sinus tachycardia and bradycardia, are characterized quantitatively by means of an ECG measurement program which has been subjected to rigorous evaluation. The analysis is performed on tracings of short duration (10 sec). The features of regularity and stability are considered for the R wavetrain. Regularity is evaluated from the normalized differences between sucessive RR intervals. Stability is determined by the ratio of maximum and minimum RR interval durations. Due to the difficulities of automatic beat-to-beat detection and measurement of P waves, an estimate of the PR interval is obtained from a pseudo-PR interval determined from certain features of the P and R wavetrains. The constancy of this pseudo-PR interval is evaluated, and its absolute value is uded as a characteristic of the type of sinus rhythm.

Conduction Disturbances in Patent Ductus Arteriosus

A study of conduction disturbances in 200 patients with patent ductus arteriosus was carried out.

The atrioventricular (AV) conduction was found generally disturbed as compared with normal cases. A significant delay in AV conduction was demonstrated by the high incidence (10.5 per cent) of first-degree AV block, by the elevated percentage of high values of the P-R index and by a high mean P-R index in the whole series (0.85 versus 0.75 in normal subjects).

After surgery a significant improvement in AV conduction was noted. First-degree AV block disappeared in 79 per cent of the cases, and in some instances the block decreased in intensity. In cases without diagnosis of AV block the improvement, as manifested by the diminution of the P-R index, was observed in 62 per cent of the cases. The improvement in AV conduction was greater in those groups with higher preoperative P-R index. The impression was that a large number of cases with high values of the P-R index, although still below the upper limit of normal (1.00), actually have first-degree AV block, undiagnosed by the usual criteria. The mean P-R index after surgery for the whole group was 0.79.

It was suggested that the AV conduction disturbances in patent ductus arteriosus are related, in some way, to the hemodynamic conditions of this entity and particularly to the left-to-right shunt between aorta and pulmonary artery.

Six cases (3 per cent) of incomplete right bundle-branch block and five (2.5 per cent) of incomplete left bundle-branch block were found. These disturbances did not change after surgery.