Can cardiac pacing prevent neurocardiogenic syncope?
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Bradycardia↗
Biomedical subjects
C P Shah
Publications and source records attributed to C P Shah.
Role of weight-bearing flexion and extension myelography in evaluating the intervertebral disc.
Magnetic resonance imaging has many advantages compared with myelography and/or computed tomography in evaluating the lumbar spine for herniated nucleus pulposus. The authors have included a series of three patients whose histories and physical examinations were clinically suggestive of herniated nucleus pulposus but whose magnetic resonance imaging scans were interpreted by a radiologist as a disc bulge without nerve root compression. Because all patients had not responded to a conservative care treatment program and surgical intervention was to be considered, subsequent testing with lumbar myelography with weight-bearing flexion and extension views demonstrated more clearly the presence of herniated nucleus pulposus along with compression of the nerve root; it also revealed that a positional change in the disc occurred with flexion and extension.
Adult↗
Sciatic neuropathy secondary to infiltrating intermuscular lipoma of the thigh.
Sciatic neuropathy is a rare mononeuropathy of the lower limbs that is commonly misdiagnosed as spinal stenosis or herniated nucleus pulposus. We describe an unusual case in which a patient underwent surgical excision of a large soft-tissue mass on his right side that involved the posterior and medial compartment of the thigh with displacement of the sciatic nerve posteriorly. The patient had full resolution of his pain and restoration of his neurologic function.
Electromyography↗
Dual chamber pacing for neurally mediated syncope with a prominent cardioinhibitory component.
The role of cardiac pacing for treatment of recurrent neurally mediated syncope (NMS) remains controversial. We hypothesized that dual chamber pacing in NMS patients with a prominent cardioinhibitory component may be beneficial. Twelve patients (mean age = 37.8+/-17 years, range 15-78 years, 7 men and 5 women) with a mean of 4+/-2.2 episodes of syncope underwent tilt table evaluation. Patients were passively tilted to 70 degrees head-up position for 20 minutes and then returned to the supine position. Isoproterenol was then infused at 1-2 microg/min to increase heart rate by > or = 25% and tilt was repeated. Patients lost consciousness after 16+/-6 minutes of tilt; nine patients had syncope in the baseline state and three during isoproterenol infusion. All patients had at least 5 seconds of asystole with a mean of 9.5+/-4 seconds (range 5-20 s). A dual chamber permanent pacemaker with a special feature allowing heart rate acceleration in response to bradycardia was implanted in all patients. During a mean follow-up of 18.6+/-4.2 months, 11 (92%) of these patients were free of syncope and had negative tilt table test. One (8%) patient had two episodes of syncope. We conclude that dual chamber pacing may be beneficial in patients with NMS with a prominent cardioinhibitory component.
Adolescent↗
QT dispersion may be a useful adjunct for detection of myocardial infarction in the chest pain center.
BACKGROUND: QT dispersion has been proposed as a noninvasive measurement of the degree of inhomogeneity in myocardial repolarization. Increased QT dispersion has been reported after myocardial infarction. We hypothesized that increased QT dispersion may be a useful adjunct for risk stratification in patients being evaluated in a chest pain center. METHODS AND RESULTS: Patients were admitted to the chest pain center for evaluation of chest pain. Exclusion criteria included (1) systolic blood pressure <90 mm Hg, (2) ischemia or infarction on the initial electrocardiograph (ECG), (3) elevated creatine kinase or MB fraction, and (4) chest pain associated with cocaine use. Serial creatine kinase and MB levels and ECGs were obtained at 0, 6, and 9 hours. Patients were monitored for (1) creatine kinase and MB rise, (2) ECG changes for infarction, (3) ST-segment changes, and (4) rest angina. A negative evaluation at the chest pain center led to an exercise stress test. Patients with a positive exercise stress test were admitted for further evaluation and patients with a negative exercise stress test result were discharged home. Patients were divided into 3 groups. Group 1 consisted of patients who were found to have an acute myocardial infarction (AMI), group 2 consisted of patients with prior history of coronary artery disease but no evidence of AMI, and group 3 consisted of patients without prior coronary artery disease or AMI. QT dispersion was measured on the initial ECG in all patients. A total of 586 patients were evaluated. Group 1 consisted of 13 patients with mean QT dispersion of 44.6+/-18.5 ms, group 2 consisted of 267 patients with a mean QT dispersion of 10.0+/-13.8 ms, and group 3 consisted of 303 patients with a mean QT dispersion of 10.5+/-10.0 ms. Analysis of variance showed a significantly higher QT dispersion in patients who had AMI compared with other patients with chest pain (P< .001). CONCLUSIONS: QT dispersion can be a useful diagnostic adjunct for detection of AMI in patients with chest pain with a normal ECG and normal cardiac enzymes.
Aged↗
Clinical differentiation of narrow QRS complex tachycardias.
Supraventricular tachycardias generally present with narrow QRS complexes and are quite commonly seen in the emergency department. Regular narrow QRS complex tachycardias occur in all age groups and may be associated with minimal symptoms, such as palpitations, or, present with hemodynamic compromise resulting in syncope. While history and physical examination are indispensable, they usually do not lead to a definitive diagnosis. The diagnosis is made by careful analysis of the 12-lead ECG. Therapy is based on hemodynamic assessment and understanding of the tachycardia mechanism.
Diagnosis, Differential↗
Clinical approach to wide QRS complex tachycardias.
Wide QRS complex tachycardia is a frequently encountered arrhythmia in the emergency department and presents a diagnostic challenge to the emergency physician. The history, physical examination, chest radiograph, and electrocardiogram analysis are important in making the correct diagnosis. The diagnosis of ventricular tachycardia is supported by, 1) a history of prior myocardial infarction or congestive heart failure; 2) a physical examination showing cannon A-waves in the jugular venous pulsation or variable heart sounds; 3) a chest radiograph showing cardiomegaly or evidence of prior cardiac surgery; and 4) characteristic ECG features that include AV dissociation, fusion-capture beats, QRS concordance, or, typical morphologic features in leads V1 and V6. This article presents the diagnostic and therapeutic approaches to wide QRS tachycardias.
Diagnosis, Differential↗
Permanent cardiac pacing.
Implantation of a permanent pacemaker is the most commonly performed surgical operation involving the heart. The modern cardiac pacemaker is a complex device that can sense and pace in both the atrium and ventricle. It also modulates the pacing rate based on sensed physiologic parameters. This article reviews the fundamental principles of pacemaker technology and provides the emergency physician with approaches to common pacemaker problems.
Electrocardiography↗
Implantable cardioverter defibrillators.
Implantable cardioverter defibrillators have proven to be an effective therapy for life-threatening ventricular arrhythmias. Given the ever-increasing number of patients who have these devices, increasing numbers of patients are likely to present to emergency departments with defibrillator-related problems. This article discusses normal device function, indications for implantation, and technique of implantation. It also focuses on the evaluation and management of patients with these devices presenting to the emergency department.
Arrhythmias, Cardiac↗
Spongy left ventricular myocardium in an adult.
"Spongy left ventricular myocardium," or noncompaction of left ventricular myocardium, is a rare disorder of endomyocardial morphogenesis. It is usually seen in the pediatric population and is often associated with other congenital cardiac malformations. We describe an adult with noncompaction of left ventricular myocardium without associated congenital cardiac anomalies.
Adolescent↗
A useful marker during ablation.
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Adult↗
The impact of unemployment on health: a review of the evidence.
OBJECTIVE: To review the scientific evidence supporting an association between unemployment and adverse health outcomes and to assess the evidence on the basis of the epidemiologic criteria for causation. DATA SOURCES: MEDLINE was searched for all relevant articles with the use of the MeSH terms "unemployment," "employment," "job loss," "economy" and a range of mortality and morbidity outcomes. A secondary search was conducted for references from the primary search articles, review articles or published commentaries. Data and definitions of unemployment were drawn from Statistics Canada publications. STUDY SELECTION: Selection focused on articles published in the 1980s and 1990s. English-language reports of aggregate-level research (involving an entire population), such as time-series analyses, and studies of individual subjects, such as cross-sectional, case-control or cohort studies, were reviewed. In total, the authors reviewed 46 articles that described original studies. DATA EXTRACTION: Information was sought on the association (if any) between unemployment and health outcomes such as mortality rates, specific causes of death, incidence of physical and mental disorders and the use of health care services. Information was extracted on the nature of the association (positive or negative), measures of association (relative risk, odds ratio or standardized mortality ratio), and the direction of causation (whether unemployment caused ill health or vice versa). DATA SYNTHESIS: Most aggregate-level studies reported a positive association between national unemployment rates and rates of overall mortality and mortality due to cardiovascular disease and suicide. However, the relation between unemployment rates and motor-vehicle fatality rates may be inverse. Large, census-based cohort studies showed higher rates of overall mortality, death due to cardiovascular disease and suicide among unemployed men and women than among either employed people or the general population. Workers laid off because of factory closure have reported more symptoms and illnesses than employed people; some of these reports have been validated objectively. Unemployed people may be more likely than employed people to visit physicians, take medications or be admitted to general hospitals. A possible association between unemployment and rates of admission to psychiatric hospitals is complicated by other institutional and environmental factors. CONCLUSIONS: Evaluated on an epidemiologic basis, the evidence suggests a strong, positive association between unemployment and many adverse health outcomes. Whether unemployment causes these adverse outcomes is less straightforward, however, because there are likely many mediating and confounding factors, which may be social, economic or clinical. Many authors have suggested mechanisms of causation, but further research is needed to test these hypotheses.
Accidents, Traffic↗
Fatal pontine metastasis: clinical, CT, MRI and pathological correlates.
Progressive brainstem and cerebellar signs developed in a previously healthy 70-year-old man over a course of seven days. A pontine mass characterized by CT and MRI suggested an infiltrating primary pontine glioma. Gross postmortem examination showed a medullary-pontine hemorrhage. Microscopic analysis disclosed an undifferentiated large cell carcinoma which was found to originate from the lung. Differential diagnoses in cases of suspected brainstem lesions are given, including metastatic tumors which are rare when presenting as a solitary brainstem mass. Optimal patient management should be formulated on the basis of histopathological diagnosis rather than imprecise imaging data. Exact tissue diagnosis will also avoid an extensive and expensive search for an occult systemic cancer. The roles of radiation, chemotherapy and surgery are also discussed.
Aged↗
The health of children of low-income families.
Childhood poverty is common in Canada: 1,114,000 children under 16 years of age live below the poverty line. The incidence is highest among children of single mothers, unemployed parents, Canadian native peoples and recent immigrants, particularly refugees. Compared with the national average, the infant mortality rate is twice as high, deaths from infectious diseases are 2.5 times more common and accidental deaths are twice as common among children of low-income families. Other problems associated with poverty are iron deficiency anemia, dental caries, chronic ear infections, mental retardation, learning disabilities, poor school performance and increased suicide rates. Health care professionals can help address the poor physical and mental health associated with poverty in children by promoting a broad range of public policies.
Adolescent↗
Pulsed Doppler frequency and carotid stenosis.
Two hundred and forty-two internal carotid arteries (ICA) were evaluated by independently interpreted arteriography and pulsed Doppler spectrum analysis using ultrasonic arteriography to evaluate the ability of peak systolic frequency (PSF) to predict the degree of internal carotid stenosis. Mean PSF in the 129 (53.3%) high grade ICA stenoses of greater than 50% diameter reduction was 6.55 +/- 0.14 (SEM) khz, while mean PSF in the 113 (46.7%) low grade (less than 50% diameter reduction) stenoses was 3.38 +/- 0.12 (SEM) kHz (P less than 0.0001). Receiver-operator characteristic (ROC) analysis revealed that PSFs of 4.5 kHz (sensitivity 87%, specificity 88%) and 5.0 kHz (sensitivity 83%, specificity 93%) were best for identifying a 50% diameter stenosis. Positive predictive value of 5.0 kHz was 93% (107/115) and negative predictive value was 82.7% (105/127). Linear regression analysis of PSF in kHz versus percentage diameter reduction yielded the equation: % stenosis = 10.7 (PSF) - 4.1 (r = 0.76). A nonlinear equation was also derived: % stenosis = 61.9 - 33.5 (PSF) + 8.7 (PSF)2 - 0.5 (PSF)3 (r = 0.77). Based on this analysis peak systolic frequency criteria measured by pulsed Doppler spectrum analysis appear to be useful for distinguishing high grade from low grade stenoses. Both the linear and nonlinear equations further suggest that PSF can more precisely quantitate the degree of ICA luminal narrowing.
Carotid Artery Diseases↗
Prevalence of hypertension, obesity and smoking in three Indian communities in northwestern Ontario.
Hypertension is perceived to be an important problem among native people in Canada, but specific prevalence data have not been accumulated. A study was carried out to determine community levels of blood pressure and to document the prevalence of hypertension, obesity and cigarette smoking in nonurban Indians in three communities in northwestern Ontario. Of the 678 people present in the communities at the time of the survey 668 (98.5%) participated. Age- and sex-specific mean diastolic and systolic blood pressure readings are presented. The overall prevalence rate of hypertension was 13%; in 9.6% of those with hypertension the condition had previously been diagnosed. Blood pressure generally rose with increasing age, but diastolic pressure declined after age 50 in both sexes. The rate of obesity increased with increasing age; 70% of women aged 35 to 64 years and 50% of men aged 35 to 44 years were obese. Over half (56.4%) of the study population smoked, and most smokers were less than 35 years old.
Adolescent↗
Comparative efficacy of digoxin, hydralazine and combination therapy in chronic congestive heart failure.
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Adult↗
The health of Indians in Canadian cities: a challenge to the health care system.
It is well known that Canadian native people living on reserves have high morbidity and mortality rates, but less is known about the health of those who migrated to urban centres. Several studies have shown that these people have high rates of mental health problems, specific diseases, injuries, infant death and hospital admission. In addition, there is evidence that cultural differences create barriers to their use of health care facilities. The low socioeconomic status, cultural differences and discrimination that they find in cities are identified as the primary blocks to good health and adequate health care. More epidemiologic studies need to be done to identify health problems, needs and barriers to health care. Federal, provincial and civic governments along with the appropriate departments of faculties of medicine should begin working with native organizations to improve the health of native people living in Canada's cities.
Adult↗