Using GIS Mapping to Target Public Health Interventions: Examining Birth Outcomes Across GIS Techniques.

With advances in spatial analysis techniques, there has been a trend in recent public health research to assess the contribution of area-level factors to health disparity for a number of outcomes, including births. Although it is widely accepted that health disparity is best addressed by targeted, evidence-based and data-driven community efforts, and despite national and local focus in the U.S. to reduce infant mortality and improve maternal-child health, there is little work exploring how choice of scale and specific GIS visualization technique may alter the perception of analyses focused on health disparity in birth outcomes. Retrospective cohort study. Spatial analysis of individual-level vital records data for low birthweight and preterm births born to black women from 2007 to 2012 in one mid-sized Midwest city using different geographic information systems (GIS) visualization techniques [geocoded address records were aggregated at two levels of scale and additionally mapped using kernel density estimation (KDE)]. GIS analyses in this study support our hypothesis that choice of geographic scale (neighborhood or census tract) for aggregated birth data can alter programmatic decision-making. Results indicate that the relative merits of aggregated visualization or the use of KDE technique depend on the scale of intervention. The KDE map proved useful in targeting specific areas for interventions in cities with smaller populations and larger census tracts, where they allow for greater specificity in identifying intervention areas. When public health programmers seek to inform intervention placement in highly populated areas, however, aggregated data at the census tract level may be preferred, since it requires lower investments in terms of time and cartographic skill and, unlike neighborhood, census tracts are standardized in that they become smaller as the population density of an area increases.

Adenosine-induced atrioventricular block: a rapid and reliable method to assess surgical and radiofrequency catheter ablation of accessory atrioventricular pathways.

Adenosine has been shown to inhibit anterograde and retrograde conduction through the atrioventricular (AV) node while having little or no effect on accessory pathway conduction. Its rapid onset of action and short half-life make it particularly suitable for repetitive measurements. In this study, the utility of adenosine was tested in assessing completeness of accessory pathway ablation. Sixteen patients with an accessory pathway were studied (eight surgical ablations, eight catheter ablations with radiofrequency energy). Before ablation, no accessory pathway was sensitive to adenosine. Twelve patients with pre-excitation showed high grade AV node block with maximal pre-excitation on the administration of adenosine during atrial pacing. Four patients with a concealed accessory pathway demonstrated high grade AV block without evidence of latent anterograde accessory pathway conduction. Preablation ventriculoatrial (VA) block was not observed in any of the 16 patients in response to adenosine during ventricular pacing. Immediately after accessory pathway ablation, all patients developed AV and VA block with the administration of adenosine during atrial and ventricular pacing, respectively. These findings were confirmed during follow-up study 1 week later. Atrioventricular block during atrial and ventricular pacing with adenosine affords a reliable and immediate assessment of successful pathway ablation.

Induction of atrioventricular node reentrant tachycardia with adenosine: differential effect of adenosine on fast and slow atrioventricular node pathways.

OBJECTIVES: This study sought to evaluate the sensitivity of fast and slow atrioventricular (AV) node pathways to incremental doses of adenosine in patients with typical AV node reentrant tachycardia. BACKGROUND: Although adenosine is known to depress conduction through the AV node, the relative sensitivity to adenosine of the anterograde fast and slow pathways in patients with dual AV node pathways and typical AV node reentrant tachycardia has not previously been studied. METHODS: Sixteen patients with dual AV node physiology and typical AV node reentrant tachycardia and 10 control patients were given incremental doses of adenosine during atrial pacing. RESULTS: In 14 of 16 patients with dual-AV node physiology, administration of small doses of adenosine during atrial pacing led consistently to transient block of impulse conduction in the fast pathway before block in the slow pathway, resulting in abrupt prolongation of the AH interval with continued 1:1 AV conduction. The mean (+/- SD) doses of adenosine required to cause conduction block in the fast and slow pathways were 2.7 +/- 3.0 and 7.2 +/- 4.7 mg, respectively (p = 0.004). In 9 of 16 patients, administration of low dose adenosine led to initiation of AV node reentrant tachycardia. The control patients showed no abrupt increases in AH interval with administration of adenosine during atrial pacing. CONCLUSIONS: In most patients with dual AV node pathways and typical AV node reentrant tachycardia, the fast pathway is more sensitive than the slow pathway to the effects of adenosine.

Motor vehicle accidents in patients with an implantable cardioverter-defibrillator.

OBJECTIVES: This study was designed to examine driving safety in patients at risk for sudden death after implantation of a cardioverter-defibrillator. BACKGROUND: Cardioverter-defibrillators are frequently implanted in patients at high risk for sudden death. Despite concern about the safety of driving in these patients, little is known about their actual motor vehicle accident rates. METHODS: Surveys were sent to all 742 physicians in the United States involved in cardioverter-defibrillator implantation and follow-up. Physicians were questioned about numbers of patients followed up, numbers of fatal and nonfatal accidents, physician recommendations to patients about driving and knowledge of state driving laws. RESULTS: Surveys were returned by 452 physicians (61%). A total of 30 motor vehicle accidents related to shocks from implantable defibrillators were reported by 25 physicians over a 12-year period from 1980 to 1992. Of these, nine were fatal accidents involving eight patients with a defibrillator and one passenger in a car driven by a patient. No bystanders were fatally injured. There were 21 nonfatal accidents involving 15 patients, 3 passengers and 3 bystanders. The estimated fatality rate for patients with a defibrillator, 7.5/100,000 patient-years, is significantly lower than that for the general population (18.4/100,000 patient-years, p < 0.05). The estimated injury rate, 17.6/100,000 patient-years, is also significantly lower than that for the general public (2,224/100,000 patient-years, p < 0.05). Only 10.5% (30 of 286) of all defibrillator discharges during driving resulted in accidents. Regarding physician recommendations, most physicians (58.1%) ask their patients to wait a mean (+/- SD) of 7.3 +/- 3.4 months after implantation or a shock before driving again. CONCLUSIONS: The motor vehicle accident rate caused by discharge from an implantable cardioverter-defibrillator is low. Although restricting driving for a short period of time after implantation may be appropriate, excessive restrictions or a total ban on driving appears to be unwarranted.

ACC policy statement. Recommended guidelines for training in adult clinical cardiac electrophysiology. Electrophysiology/ Electrocardiography Subcommittee, American College of Cardiology.

Training in clinical cardiac electrophysiology should take place in an Accreditation Council for Graduate Medical Education accredited cardiology program, and the electrophysiology training program itself should be accredited by the Council. Each trainee must be eligible for board certification in Internal Medicine and either eligible for certification in Cardiovascular Diseases or in a program leading to eligibility. Training faculty should be certified in clinical cardiac electrophysiology or demonstrate equivalent credentials. At least two training faculty members are preferred. The faculty must be dedicated to teaching, active in performing or promoting research and must spend a substantial portion of their time in research, teaching and practice of clinical electrophysiology. A curriculum of training should be established. Faculty experts in the related basic sciences should be available and involved in teaching. The institution should have a fully equipped clinical electrophysiology laboratory and complete noninvasive capabilities. A close working relation with a cardiac surgery faculty member skilled in surgical treatment of arrhythmias is required. Training in application of pharmacologic and all current nonpharmacologic therapies, in the outpatient and inpatient setting, is necessary. The clinical exposure must include all facets of arrhythmia diagnosis and treatment and must be quantitatively sufficient to allow the trainee to develop proficiency. The period of training should not be less than one year in addition to the period of cardiology fellowship required by the ABIM for board eligibility. A continuous period of training is preferred.

Life-threatening ventricular arrhythmias due to transient or correctable causes: high risk for death in follow-up.

OBJECTIVES: This study evaluated the prognosis of patients resuscitated from ventricular tachycardia (VT) or ventricular fibrillation (VF) with a transient or correctable cause suspected as the cause of the VT/VF. BACKGROUND: Patients resuscitated from VT/VF in whom a transient or correctable cause has been identified are thought to be at low risk for recurrence and often receive no primary treatment for their arrhythmias. METHODS: In the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients with a potentially transient or correctable cause of VT/VF were not eligible for randomization. The mortality of these patients was compared with the mortality of patients with a known high risk of recurrence of VT/VF in the AVID registry. RESULTS: Compared with patients having high risk VT/VF, those with a transient or correctable cause for their presenting VT/VF were younger and had a higher left ventricular ejection fraction. These patients were more often treated with revascularization as the primary therapy, more commonly received a beta-blocker, less often required therapy for congestive heart failure and less commonly received either an antiarrhythmic drug or an implantable cardioverter defibrillator. Nevertheless, subsequent mortality of patients with a transient or correctable cause of VT/VF was no different or perhaps even worse than that of the primary VT/VF population. CONCLUSIONS: Patients identified with a transient or correctable cause for their VT/VF remain at high risk for death. Further research is needed to define truly reversible causes of VT/VF. Meanwhile, these patients may require more aggressive evaluation, treatment and follow-up than is currently practiced.

Characteristic variation in evoked potential amplitude with changes in pacing stimulus strength.

The evoked potential, the intracardiac signal generated by a pacing stimulus, shows promise as a sensor for rate-responsive pacing and automatic threshold determinations. Thus, it is important to understand factors that may alter the morphology of evoked potentials and affect accurate signal analysis. Using a computer-based pacing system emulator, stimuli at 2.5, 5.0 and 6.9 V were delivered to 12 patients through permanent bipolar pacing leads. At 2.5 V, the evoked potential amplitude measured -12.63 +/- 7.79 mV. When the pacing amplitude was increased to 5.0 and 6.9 V, the signal diminished in size or reversed in polarity, or both, averaging -0.83 +/- 7.82 mV and 0.64 +/- 7.0 mV, respectively (p less than 0.01 vs 2.5 V). Pacing at 2.5 V was performed in an additional 8 patients with temporary quadripolar electrode catheters. With the distal pole of the catheter as the cathode and the proximal 3 poles as a common anode, the evoked potential averaged -9.01 +/- 5.44 mV. With the proximal 2 poles of the catheter disconnected to make the anode equal in size and current density to the cathode, the evoked potential diminished to -0.94 +/- 11.27 mV (p less than 0.05). There is thus a decrease in the evoked potential at high stimulus amplitudes compared to that obtained at the cathodic threshold. This finding can be reproduced by manipulation of the size and current density of the anode, suggesting that anodal stimulation at the ring of permanent pacing leads may be responsible.

QT dispersion is a marker for life-threatening ventricular arrhythmias after atrioventricular nodal ablation using radiofrequency energy.

QT dispersion has been cited as a measure of nonuniform myocardial repolarization and a predictor of sudden cardiac death. We describe 38 patients who underwent atrioventricular nodal ablation, 3 of whom had an increase in measured QT dispersion and experienced potentially fatal, pulseless, polymorphic ventricular tachycardia after the procedure.

Clinical improvement after atrioventricular nodal ablation for atrial fibrillation does not correlate with improved ejection fraction.

A retrospective review of 15 patients with atrial fibrillation and class III to IV congestive heart failure who underwent atrioventricular nodal ablation demonstrated a marked improvement in their functional abilities. This improvement, however, could not be explained by the improvement in ejection fraction alone.

Epicardial cardioverter-defibrillators do not cause postoperative arrhythmias. The CABG Patch Trial Investigators. Coronary Artery Bypass Graft.

The CABG Patch Trial is a controlled, multicenter clinical trial that randomized high-risk patients undergoing coronary artery bypass grafting (CABG) to prophylactic implantation of an epicardial implantable cardioverter-defibrillator (ICD) or to no additional treatment, permitting a controlled evaluation of the effect of epicardial ICDs on the incidence of postoperative arrhythmias. We found no significant difference in the development of postoperative arrhythmias between patients who received epicardial ICDs and the control group treated with CABG alone.

Influence of patient characteristics in the selection of patients for defibrillator implantation (the AVID Registry). Antiarrhythmics Versus Implantable Defibrillators.

The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial is a prospective, randomized study of treatment for life-threatening ventricular arrhythmias. Patients who are eligible for the main trial but who are not enrolled for any reason are followed in a registry. The objective of the present study was to determine whether there are identifiable patient characteristics among these registry patients that may influence whether a patient is treated with an implantable defibrillator. The 914 patients in the registry were divided into 2 groups according to whether the primary treatment was an implantable defibrillator. The mean age of defibrillator patients was 60 years, compared with 65 years in the nondefibrillator group (p <0.001). Only 11.2% of defibrillator recipients were minorities, whereas the percentage of minorities in the nondefibrillator group was 18.7% (p <0.003). A history of recurrent ventricular fibrillation was more likely in the group treated with defibrillators (8.9% vs 4.4%, p <0.01), whereas a history of atrial fibrillation or diabetes mellitus were both significantly more likely in the nondefibrillator group. Among defibrillator patients, a higher proportion had ventricular fibrillation as the index arrhythmia; patients with ventricular tachycardia were significantly more likely to be treated without devices. In this prospective but nonrandomized cohort of patients treated for life-threatening ventricular arrhythmias, older age, minority status, and comorbidity reduced the chances that a patient would be treated with a defibrillator.

The contribution of baseline weight and weight gain to blood pressure change in African Americans: the Pitt County Study.

PURPOSE: The positive association between obesity and blood pressure has been less consistent in African Americans than whites. This is especially true for African American men. This study investigated the sex-specific associations between baseline body mass index (BMI), weight change (kilograms), and five-year hypertension incidence and changes in blood pressure in a cohort of African Americans ages 25-50 years at baseline. METHODS: The Pitt County Study is a longitudinal investigation of anthropometric, psychosocial, and behavioral predictors of hypertension in African Americans. Data were obtained through household interviews and physical examinations in 1988 and 1993. RESULTS: Baseline BMI was positively and independently associated with changes in blood pressure after controlling for weight change and other covariates. When participants were stratified by sex-specific overweight vs. nonoverweight status at baseline, weight gain was significantly associated with increases in blood pressure only among the initially nonoverweight. CONCLUSIONS: Baseline weight for all respondents, and weight gain among the nonoverweight at baseline, were independent predictors of blood pressure increases in this cohort of African Americans.

Completeness and timeliness of tuberculosis case reporting. A multistate study.

BACKGROUND: Tuberculosis (TB) control activities are contingent on the timely identification and reporting of cases to public health authorities to ensure complete assessment and appropriate treatment of contacts and identification of secondary cases. We report the results of a multistate evaluation of completeness and timeliness of reporting of TB cases in the United States during 1993 and 1994. METHODS: To determine completeness of TB reporting, laboratory log books, death certificates, hospital discharge, Medicaid databases, and pharmacy databases were reviewed in seven states to identify possible unreported cases. Timeliness of TB reporting was calculated using the number of days between date of TB diagnosis and date of report to the local or state health department. Cases reported >7 days after diagnosis were considered to have delayed reporting. RESULTS: Of 2711 cases identified through review of secondary data sources, 14 (0.5%) were previously unreported to public health. The largest yield of unreported cases was identified through review of laboratory records; 13 of the 14 unreported cases were identified, of which eight were found only through this method. Timeliness of reporting varied between sites from a median of 7 days to a median of 38 days. The number of cases with delayed reporting varied from 5% to 53% between sites. Factors associated with delayed reporting included infectiousness, type of provider, diagnosing provider, and reporting source. CONCLUSIONS: Through a review of several different secondary data sources, few unreported TB cases were detected; however, timeliness of reporting was poor among the reported cases.

Analysis of Mycobacterium tuberculosis transmission patterns in a homeless shelter outbreak.

SETTING: From July 1997 through May 1998, ten tuberculosis (TB) cases were reported among men in a Syracuse New York homeless shelter for men. OBJECTIVE AND DESIGN: Investigation to determine extent of, and prevent further, transmission of Mycobacterium tuberculosis. RESULTS: Epidemiologic and laboratory evidence suggests that eight of the ten cases were related. Seven cases had isolates with matching six-band IS6110 DNA fingerprints; the isolate from another case had a closely related fingerprint pattern and this case was considered to be caused by a variant of the same strain. Isolates from eight cases had identical spoligotypes. The source case had extensive cavitary disease and stayed at the shelter nightly, while symptomatic, for almost 8 months before diagnosis. A contact investigation was conducted among 257 shelter users and staff, 70% of whom had a positive tuberculin skin test, including 21 with documented skin test conversions. CONCLUSIONS: An outbreak of related TB cases in a high-risk setting was confirmed through the use of IS6110 DNA fingerprinting in conjunction with spoligotyping and epidemiologic evidence. Because of the high rate of infection in the homeless population, routine screening for TB and preventive therapy for eligible persons should be considered in shelters.

Termination and suppression of idiopathic left ventricular tachycardia by diltiazem.

Idiopathic left ventricular tachycardia is known to be responsive to verapamil in many cases. However, the role of other calcium-channel blockers, such as diltiazem, in treating this specific type of ventricular tachycardia is unknown. We report a case of idiopathic left ventricular tachycardia in a patient with a structurally normal heart, which was terminated and suppressed in the electrophysiology laboratory by a single dose of diltiazem intravenously, and was subsequently suppressed long-term with sustained-release diltiazem. Our finding suggests that idiopathic left ventricular tachycardia may be managed effectively with diltiazem in both the acute and chronic settings.

Accelerated idioventricular rhythm detected during elective surgery in a healthy man.

Accelerated idioventricular rhythm (AIVR) is found most commonly in the presence of underlying heart disease. It is characterized by acceleration of a latent pacemaker that normally depolarizes slowly. We describe a 30-year-old man who was found to have episodes of accelerated idioventricular rhythm (AIVR) on cardiac monitoring during elective orthopedic surgery. Noninvasive evaluation including two-dimensional echocardiography was unremarkable. No late potentials were detected on a signal-averaged electrocardiogram. During an exercise tolerance test, AIVR was suppressed as heart rate increased. A 24-h Holter monitor revealed that the AIVR rate was consistently 73-76 beats/min, which appeared whenever the sinus rate slowed to this level. The patient has been asymptomatic, and the rhythm has persisted at least through a 5-month follow-up period.

Oversensing of atrial flutter in the recipient atrium of a heart transplant patient with a permanent atrial pacemaker.

Sinus node dysfunction requiring permanent pacemaker implantation is a common problem following heart transplantation. There are unique problems to consider in pacing the transplanted heart. This report describes a case of far-field sensing of atrial flutter in the recipient atrial remnant, with resultant inhibition of the atrial pacemaker in the donor atrium, and symptomatic bradycardia. Although postulated to be a potential problem, oversensing of the recipient atrium has not been reported prior to this case. Awareness of this problem will provide for more effective pacemaker troubleshooting.

Advanced cardiac life support: update on recent guidelines and a look at the future.

The objectives of this article are to provide an update of the American Heart Association (AHA) 1992 National Conference guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care and to review the investigation and development of new methods of CPR which may be considered in future recommendations. Despite an organized approach to sudden cardiac arrest, survival in patients receiving CPR is in the range of 5-15%. The new AHA guidelines recommend standard manual CPR performed at a rate of 80-100 compressions/min and organized algorithms of advanced cardiac life support. These guidelines stress widespread community training and rapid response in the following sequence: (1) recognition of early warning signs, (2) activation of the emergency medical system (EMS), (3) basic CPR, (4) early defibrillation, (5) intubation, and (6) intravenous medication. Several new recommendations pertain specifically to in-hospital care and are, therefore, particularly relevant to physician management of cardiac arrest. The best predictor of survival in patients requiring circulatory support after cardiac arrest is attainable coronary and cerebral perfusion. Unfortunately, the minimal levels of end-organ perfusion required to sustain life are often difficult or impossible to achieve with standard manual cardiopulmonary resuscitation and several new techniques have therefore been introduced. The most promising of these techniques are (1) interposed abdominal compression, (2) pneumatic vest, and (3) active compression-decompression resuscitation. Each of these techniques offers unique advantages when compared with standard manual cardiopulmonary resuscitation. The 1992 National Conference recommendations provide a rational framework for the resuscitation of cardiac arrest victims. New methods of cardiopulmonary resuscitation are now available and investigation into these methods continues.(ABSTRACT TRUNCATED AT 250 WORDS)

Termination of pacemaker-mediated tachycardia by adenosine.

A 30-year-old woman was referred for follow-up right- and left-heart catheterization 4 years after cardiac transplantation. She had an implanted epicardial pacemaker for bradycardia; this was programmed to the DDD mode. At the time of her catheterization, as a pigtail catheter was pulled back across the aortic valve, runs of premature ventricular complexes occurred and tachycardia with ventricular pacing spikes and ventricular capture was initiated at a rate of 126 beats/min. Adenosine 6 mg was given intravenously through a femoral venous sheath and within 20 s the tachycardia broke. The tachycardia was consistent with pacemaker-mediated tachycardia (PMT), a circus movement tachycardia occurring when ventricular pacing causes retrograde atrial depolarization followed by triggering of ventricular pacing. With reprogramming of the pacemaker to an AV delay of 160 ms and a postventricular atrial refractory period of 300 ms, no further episodes of PMT have occurred. This case illustrates that intravenous adenosine can effectively terminate PMT by causing ventriculoatrial block, thus interrupting the reentrant circuit by eliminating retrograde atrial activation.

Emergency intracardiac defibrillation for refractory ventricular fibrillation.

Hemodynamically unstable ventricular arrhythmias induced during electrophysiologic testing almost always respond to prompt application of direct current transthoracic shocks. In rare cases, however, ventricular fibrillation may be refractory to conventional treatment. Recently, a technique of intracardiac defibrillation has been successfully used to resuscitate patients with ventricular fibrillation refractory to transthoracic defibrillation. We describe two patients with a history of myocardial infarction and left ventricular dysfunction who were admitted with symptomatic episodes of ventricular tachycardia. Both had inducible sustained monomorphic ventricular tachycardia. During a repeat electrophysiologic study in Patient No. 1 on procainamide and at the initial study in Patient No. 2, right ventricular burst pacing to terminate ventricular tachycardia resulted in ventricular fibrillation refractory to resuscitation efforts, including transthoracic defibrillation with 360 J. Emergency intracardiac defibrillation with 200 and 360 J, respectively, successfully converted both patients to sinus rhythm. Both patients were subsequently discharged from the hospital on amiodarone. These cases illustrate the life-saving capabilities of intracardiac defibrillation.