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Biomedical subjects

J L Cox

Publications and source records attributed to J L Cox.

At least 73 records · Page 4Linked to original sources
PubMed1998

Efficacy of an in-feed formulation of ivermectin against somatic larvae of Strongyloides ransomi in pregnant swine.

OBJECTIVE: To confirm that ivermectin fed for 7 days to pregnant sows controls transmission of Strongyloides ransomi larvae to pigs via the colostrum or milk. ANIMALS: 24 mixed-breed sows. PROCEDURE: The sows were infected with 250,000 S ransomi larvae on 3 occasions (days 63, 64, or 65, days 71 or 73, and days 78, 79, or 80 of gestation). Eight sows received ivermectin at a dosage of 100 micrograms of ivermectin/kg of body weight/d from days 92 to 99 of gestation, and 8 sows were treated from days 103 to 110 of gestation; 8 remaining sows received unmedicated vehicle. Numbers of S ransomi larvae were counted in samples of colostrum or milk collected 1, 2, and 7 days after parturition. At 7 and 14 days after parturition, fecal samples were collected from each sow and from 4 pigs from each litter for determination of nematode egg counts; at the latter date, pigs were euthanatized and necropsied for worm counting. RESULTS: Pigs born to ivermectin-treated sows had significantly (P < 0.01) fewer adult S ransomi than did those born to control sows; efficacy was 100%. Treated sows had significantly (P < 0.05) fewer S ransomi larvae in colostrum/milk samples taken 1, 2, and 7 days after parturition than did control sows; efficacy was 100%, with the exception of 1 S ransomi larva found in a milk sample from 1 treated sow at 2 days after parturition. CONCLUSION AND CLINICAL RELEVANCE: Ivermectin fed to sows during the last third of gestation at a dosage of 100 micrograms/kg/d for 7 consecutive days is highly efficacious for control of transmission of infective S ransomi larvae to pigs via colostrum or milk.

Animals↗
PubMed1998

Nonpalpable stage T1c prostate cancer: prediction of insignificant disease using free/total prostate specific antigen levels and needle biopsy findings.

PURPOSE: Approximately 25% of radical prostatectomies performed for stage T1c disease show potentially insignificant prostate cancer. We previously reported the use of serum prostate specific antigen (PSA) density and needle biopsy findings to predict potentially insignificant cancer. We now evaluate whether using free/total serum PSA levels along with needle biopsy findings can better predict tumor significance. MATERIALS AND METHODS: We studied 163 radical prostatectomy specimens of stage T1c prostate cancer in which free/total serum PSA levels were determined. Free/total serum PSA levels were measured with Tandem-MP PSA assays. Insignificant prostate cancers were organ confined with tumor volumes less than 0.5 cc and Gleason score less than 7. Advanced tumors were either Gleason score 7 or greater, established extraprostatic extension with positive margins, or positive seminal vesicles or lymph nodes. Other cases were considered as moderate tumor. Moderate and advanced tumors were considered significant. RESULTS: Of the tumors 30.7% were insignificant, 49.7% moderate and 19.6% advanced. The best model to predict preoperatively insignificant tumor was a free/total PSA of 0.15 or greater and favorable needle biopsy findings (less than 3 cores involved, none of the cores with greater than 50% tumor involvement and Gleason score less than 7). Using this model of the 18 tumors predicted to be insignificant 17 were insignificant for a positive predictive value of 94.4%. Of the 145 cases that were predicted to be significant 112 were correctly predicted for a negative predictive value of 77.2%. There was only 1 tumor predicted to be insignificant which was classified as moderate. No tumor predicted to be insignificant was advanced. CONCLUSIONS: In conjunction with needle biopsy findings, free/total PSA levels accurately predict insignificant tumor in stage T1c disease.

Biopsy, Needle↗
PubMed1997

Time to treatment with thrombolytic therapy: determinants and effect on short-term nonfatal outcomes of acute myocardial infarction. Canadian GUSTO Investigators. Global Utilization of Streptokinase and + PA for Occluded Coronary Arteries.

OBJECTIVES: To characterize the extent of delay in administration of thrombolytic therapy to patients with acute myocardial infarction (AMI) in Canada, to examine patient-specific predictors of such delay and to measure the effect of delay on short-term nonfatal cardiac outcomes. DESIGN: Secondary cohort analysis of data from the first international Global Utilization of Streptokinase and tPA for Occluded Coronary Arteries (GUSTO-I) trial. SETTING: Sixty-three acute care hospitals across Canada. SUBJECTS: All 2898 Canadian patients with an AMI enrolled in GUSTO-I. MAIN OUTCOMES: Time before arrival at a hospital ("symptom-to-door" time) and time from arrival to administration of therapy ("door-to-needle" time) for patients who had an AMI outside of a hospital, in clinically relevant categories; proportions of patients with nonfatal, serious cardiac events, including shock, sustained ventricular tachycardia, ventricular fibrillation and asystole. RESULTS: Of the total number of patients enrolled, records were complete for 2708; 2542 of these patients (93.9%) had an AMI outside of a hospital. These 2542 patients presented a median 81 (interquartile range 50 to 130) minutes after the onset of symptoms, and the median time to treatment in hospital was 85 (interquartile range 61 to 115) minutes. Whereas a greater proportion of Canadian patients than of patients enrolled in GUSTO-I in other countries reached hospital within 2 hours of symptom onset (71.5% v. 61.2%, p < 0.001), a greater proportion of Canadian patients experienced in-hospital treatment delays of more than 1 hour (75.3% v. 57.1%, p < 0.001). In an analysis of all 2708 patients with complete records, both the unadjusted and adjusted odds of nonfatal cardiac events for those treated 4 to 6 hours after symptom onset were significantly higher than for those treated within 2 hours (odds ratio 1.60, 95% confidence interval 1.09 to 2.37). CONCLUSION: After arrival at a hospital, Canadian patients enrolled in GUSTO-I received thrombolytic therapy more slowly than trial enrollees in other countries. Such delays are already known to decrease the rate of short-term survival after AMI. The findings further show that long time to treatment also increases the odds of nonfatal, serious cardiac events. Hospitals and physicians caring for patients with AMI should routinely assess whether and how they can improve door-to-needle times.

Adult↗
PubMed1997

Molecular forms of prostate-specific antigen and human kallikrein 2 (hK2) in urine are not clinically useful for early detection and staging of prostate cancer.

OBJECTIVES: Prostate-specific antigen (PSA), a member of the human kallikrein (hK) family, is the most important tumor marker for early detection, staging, and monitoring of men with prostate cancer today. However, the sensitivity of serum PSA is not sufficient to be used alone for prostate cancer screening. Recently, it was reported that the serum-to-urinary total PSA ratio improves the detection of men with prostate cancer, especially in men with a serum total PSA level between 4.0 and 10.0 ng/mL. We tested this hypothesis by evaluating the clinical usefulness of this PSA ratio as well as the use of the different molecular forms of PSA and human kallikrein 2 (hK2) in urine for detection and staging of prostate cancer. METHODS: One hundred ten fresh, midstream urine specimens (prostate cancer 62, benign prostatic hyperplasia [BPH] 38, healthy male control 5, women 5) were collected. Serum total PSA, urine total PSA, urinary free PSA, urinary alpha 1-antichymotrypsin-bound PSA, and urinary hK2 levels were determined by monoclonal antibody assays (Hybritech Inc.). The serum-to-urinary total PSA ratio was calculated. RESULTS: The serum-to-urinary total PSA ratio did not accurately distinguish between men with BPH and men with prostate cancer. There was no significant difference between the urinary levels of any of the molecular forms of PSA or hK2 between men with prostate cancer and men with BPH. Among men with prostate cancer, neither urinary hK2 nor urinary levels of any of the molecular forms of PSA correlated with age, pathologic stage, or Gleason grade. CONCLUSIONS: In our study, the serum-to-urinary total PSA ratio did not improve the detection of men with prostate cancer. Furthermore, measurement of the molecular forms of PSA and hK2 in urine did not improve the detection or staging of prostate cancer over serum PSA alone.

Aged↗
PubMed1997

The maze procedure for cure of atrial fibrillation.

Atrial fibrillation is the most common dysrhythmia encountered in clinical practice. A significant number of patients fail medical therapy because of inability to convert or control the rhythm pharmacologically, intolerance of the requisite medication, or persistent symptoms despite apparently satisfactory rate control. Based on experimental studies establishing the electrophysiologic basis of atrial fibrillation, a surgical procedure has been developed that is highly effective in restoring sinus rhythm without further requirement for medications. The evolution of this procedure, its current indications, and results are outlined.

Atrial Fibrillation↗
PubMed1997

Spontaneous atrial flutter in a chronic canine model of the modified Fontan operation.

OBJECTIVES: This study sought to 1) establish whether the atrial flutter (AFL) inducible acutely occurs spontaneously in a chronic canine model, and 2) characterize any reentrant circuits present chronically. BACKGROUND: We previously demonstrated, in an acute canine model of the modified Fontan operation, that the lateral tunnel suture line creates a sufficient electrophysiologic substrate for AFL. METHODS: Using cardiopulmonary bypass, a suture line was placed through a right atriotomy in adult dogs (n = 7) to simulate the lateral tunnel of the Fontan operation. Holter recordings were made preoperatively, on the first postoperative day and 2, 4 and 6 weeks postoperatively. At 6 to 8 weeks, through bilateral ventriculotomies, 253-point unipolar atrial electrodes were inserted. AFL was induced using atrial burst pacing, and endocardial activation sequence maps were created. RESULTS: Preoperatively, all dogs were in sinus rhythm. Spontaneous AFL occurred in all dogs postoperatively, with a mean (+/-SD) cycle length of 192 +/- 22 ms. At 6 weeks postoperatively, of six dogs that survived, four had intermittent AFL, and two had incessant AFL. At reoperation, sustained AFL was inducible in six of six dogs, with a mean cycle length of 194 +/- 17 ms. Activation sequence maps demonstrated conduction block at the lateral tunnel suture line, which facilitated unidirectional conduction critical for propagation of the reentrant circuit. The AFL circuit was similar to that observed acutely. CONCLUSIONS: In a chronic canine model of the modified Fontan operation, the lateral tunnel suture line alone, in the absence of atrial stretch or hypertension, provides an electrophysiologic substrate that promotes spontaneous AFL. This model may be useful for evaluating various forms of treatment and prevention of AFL after the Fontan operation.

Animals↗
PubMed1997

Inhibition of motility and invasion of B16 melanoma by the overexpression of cystatin C.

Although increased expression of cysteine proteinases has been shown to be correlated with increased metastasis for a wide variety of tumours, the contribution of cysteine proteinases to the metastatic spread of tumour cells is not well understood. In order to examine this question we have overexpressed a specific cysteine proteinase inhibitor, cystatin C, by stable transfection of B16F10 melanoma. Increased expression of cystatin C inhibited motility and in vitro invasiveness of B16 melanoma by 50% in both stimulated (autocrine motility factor, laminin) and unstimulated cells. These results suggest that cysteine proteinases are involved in B16 melanoma motility and invasion.

Animals↗
PubMed1997

Global electrophysiological mapping of the atrium: computerized three-dimensional mapping system.

The atria are anatomically complex three-dimensional (3-D) structures. Impulse propagation is dynamic and complex during both normal conduction and arrhythmia. Atria activation has traditionally been represented on two-dimensional surface maps, which have inherent inaccuracies and are difficult to interpret. Interactive computerized 3-D display facilitates interpretation of complex atrial activation sequence data obtained from form-fitting multipoint electrodes. Accordingly, the purpose of this article is to describe the application of 3-D form-fitting electrode molds to the 3-D mapping and display system developed in this laboratory for the study of complex cardiac arrhythmias. Computer generated 3-D surface models are created from a database of serial cross-sectional anatomical images. Points chosen on endocardial and epicardial surfaces in each cross-sectional image are processed to create polygons defining myocardial wall boundaries. The polygons from adjacent serial images are then combined, to create a 3-D surface model. The discrete anatomical locations of unit electrodes on multipoint electrode templates are then assigned in the proper position on the surface model. Computer analysis of simultaneous activation data from each unit electrode is performed based on parameters set by the user. Activation data from each unit electrode site are displayed on the computer surface model in a color spectrum correlating with a user-defined time scale. Activation sequence maps can be visualized as static isochrone maps, interval maps, or as dynamic maps at variable speeds, from any 3-D perspective. Thus, an interactive computerized 3-D display system is described, which allows anatomically superior analysis and interpretation of complex atrial arrhythmias.

Arrhythmias, Cardiac↗
PubMed1997

The surgical management of atrial fibrillation.

Atrial fibrillation is the most common dysrhythmia encountered in clinical practice. For some patients, satisfactory rate control is not possible by pharmacologic means. This led us to develop a surgical approach to its cure, which in turn has led to a deeper understanding of the electrophysiologic basis of atrial fibrillation and to the development of a surgical procedure that is highly effective in restoring sinus rhythm with an acceptable mortality and morbidity. We review these findings as well as the clinical results obtained with the Maze procedure.

Adult↗
PubMed1997

Is colour flow imaging needed to exclude clinically significant valvular regurgitation in adult patients undergoing transthoracic echocardiography?

OBJECTIVE: To establish whether clinically significant aortic and mitral valvular regurgitation can be excluded in adult patients undergoing transthoracic echocardiography without using colour flow imaging. SETTING: Sunnybrook Health Science Centre, a tertiary referral centre with full cardiovascular services affiliated with the University of Toronto, Toronto, Ontario. DESIGN: Logistic regression models were developed from a retrospective review of 14,051 unselected consecutive echocardiograms from 1991 through 1994. The dependent variable was more than mild aortic or mitral valvular regurgitation. Independent variables included age, sex and various functional and structural measures obtained during routine two-dimensional echocardiography. The negative predictive values and sensitivity of the models were estimated. INTERVENTION: The number of patients correctly classified by these models, as well as the proportion for whom the colour flow imaging did not add to the baseline echocardiogram, was determined. Nonparametric bootsrapping was used to obtain confidence intervals for these statistics. MAIN RESULTS: Ten models were developed, with negative predictive values ranging from 96.2% to 100%. Incorporation of such decision aids into the software of echocardiographic machinery would help echocardiographers to rule out significant aortic or mitral regurgitant lesions. In practices where colour flow imaging is routinely employed, 40% fewer procedures could be performed. CONCLUSIONS: Models based on simple demographic and two-dimensional echocardiographic variables can reliably exclude significant valvular regurgitation and could potentially reduce the volumes and costs of colour flow imaging. Given the widespread diffusion of colour Doppler imaging, the models may also be helpful to avoid misinterpretation of flow imaging results, by defining subgroups in whom the prior probability of significant aortic or mitral regurgitation is extremely low.

Aged↗
PubMed1997

Towards improved coding of acute myocardial infarction in hospital discharge abstracts: a pilot project.

OBJECTIVE: To pilot-test a simple checklist designed to improve coding of acute myocardial infarction (AMI) in hospital discharge abstracts. BACKGROUND: Health records technologists review hospital charts to code discharge diagnoses according to the International Classification of Diseases, 9th revision (ICD-9). Many studies have suggested that there is a high false positive rate in coding AMI, ie, ICD-9 410, on hospital discharge abstracts. PATIENTS AND METHODS: The checklist required either at least two of suggestive symptoms, diagnostic electrocardiographic changes, or diagnostic rise in serum cardiac enzymes; or confirmation by autopsy. First case of use was confirmed-typical time to complete the checklist was 3 to 4 mins. Then 16 Ontario community hospitals were recruited to apply the checklist on a blinded basis to 1000 randomly drawn in-patient records-10% were audited for another study to confirm AMI; and 90% were originally coded with 'most responsible diagnosis' (MRD) of AMI, other cardiovascular diagnoses and various noncardiac conditions. Percentage agreement (95% CI) between the checklist and the confirmed or coded diagnosis was analyzed; coding of AMI as a secondary diagnosis was examined in further analyses. RESULTS: One hospital withdrew for logistical reasons; the final useable sample from 15 hospitals was 943 records. The checklist correctly identified 100% of AMIs independently confirmed for another study; usual coding identified 89.7% of cases (70 of 78; 95% CI 80.8 to 95.5). For cases not confirmed, but where the physician had nonetheless diagnosed AMI, six of 11 charts were miscoded as AMI in hospital records; none were miscoded by the checklist. For records with AMI as MRD, 11.6% (44 of 380; 95% CI 8.5 to 15.2) were classified as false positives by the checklist. Where an AMI was coded as a secondary diagnosis, 52.9% (36 of 68; 95% CI 40.5 to 65.2) met the checklist criteria for AMI. Finally, among records where the MRD was other than AMI, 6.8% (38 of 563; 95% CI 4.8 to 9.2) met checklist criteria for AMI during admission, but 94.7% had an ICD-9410 code as a secondary diagnosis. CONCLUSION: A simple checklist can be very easily applied, has extremely high sensitivity for confirming the presence of AMI, and identifies a clinically significant proportion of charts with false positive codes for AMI. Conversely, these findings support the high sensitivity (low false negative rates) of conventional coding practices for AMI in Canadian hospital records, be it as a primary or secondary diagnosis (eg, 95% detection rate). Usual coding, combined with the checklist for tentative ICD-9 410 diagnoses, would improve the accuracy of Canadian hospital records.

Canada↗
PubMed1997

Left ventricular aneurysms: pathophysiologic observations and standard resection.

For the past four decades, the standard approach to the treatment of left ventricular aneurysms has been to resect the aneurysm wall and close it in a linear fashion. During the past decade, evidence has accumulated that this simple approach may not be the most efficacious in terms of either short-term ventricular function or long-term survival and quality of life. To establish the basis against which the newer techniques are to be compared, this article describe the historical evolution of procedures designed to treat ventricular aneurysms, the pathophysiolgy of aneurysms, the standard surgical technique still used by most surgeons, and the rationale for the newer surgical approaches.

Heart Aneurysm↗
PubMed1997

Surgical management of left ventricular aneurysms: a clarification of the similarities and differences between the Jatene and Dor techniques.

In the mid 1980s, two highly innovative and entirely new approaches to the surgical treatment of left ventricular aneurysms were introduced almost simultaneously and completely independently by Dr Adib Jatene in Sao Paulo, Brazil and Dr Vincent Dor, then at the University of Nice, France and now at the Centre Cardio-Thoracique de Monaco. The similarities between these two approaches to the repair of left ventricular aneurysms and their close temporal evolution have caused confusion regarding their differences and the precise surgical technique of each approach. It is the purpose of this article to clarify the similarities and differences between these two techniques.

Heart Aneurysm↗
PubMed1996

Relationship between local atrial fibrillation interval and refractory period in the isolated canine atrium.

BACKGROUND: Atrial refractory periods and their spatial distribution are important determinants of atrial reentrant arrhythmias. The objective of this study was to demonstrate a correlation between the local atrial fibrillation interval (AFI) and local effective refractory period (ERP). METHODS AND RESULTS: To measure the local ERP and local AFI under stable conditions without hemodynamic, autonomic, or reflex influences, isolated perfused canine whole atria were used (n = 8). The isolated atria were mounted on two endocardial electrodes. Bipolar electrograms were simultaneously recorded from 253 endocardial sites, and 16 to 20 randomly distributed electrodes were used to measure the local ERP by the extrastimulus technique. In all studies, several episodes of AF were induced by a single extrastimulus. The ERP and minimum AFI converged with increasing duration of AF. The convergence was more rapid if the total duration of AF analyzed came from multiple episodes of AF. The correlation coefficient between the local ERP and minimum local AFI was .92 (n = 119, P < .001). The minimum AFI was used to construct AFI distribution maps at all 253 sites. Activation block during premature stimulation correlated with regions of long AFI. CONCLUSIONS: The minimum local AFI measured from at least 10 seconds of AF approximates the local ERP. Construction of a minimum local AFI map during AF can be used to predict the distribution of refractoriness and can be used to predict sites of functional block. Contrary to studies done in intact animals and patients, the AFI were longer than the ERPs, suggesting that reflex changes may shorten ERP in the intact heart.

Animals↗
PubMed1996

Obesity is not a risk factor for significant adverse outcomes after cardiac surgery.

BACKGROUND: Obese patients undergoing cardiac surgery are often thought to have prohibitive perioperative risk despite the lack of sufficient data to support this assumption. METHODS AND RESULTS: To assess the significance of obesity as a risk factor in patients undergoing cardiac surgery, we analyzed data from 2299 patients undergoing procedures requiring cardiopulmonary bypass from January 1, 1991, to December 31, 1993. Obesity was defined by use of the body mass index, defined as weight in kilograms divided by height in meters squared. Potential adverse outcomes analyzed included operative mortality, deep sternal wound infection, superficial sternal wound infection, infection at the saphenous vein harvest site, stroke, renal failure, adult respiratory distress syndrome, prolonged mechanical ventilation, pneumonia, sepsis, atrial arrhythmias, pulmonary embolism, need for early reexploration for bleeding, and ventricular arrhythmias. To control for the confounding effects of other risk factors, we performed a multivariate logistic regression analysis. Potential covariates considered in the logistic model included age, sex, race, history of reoperation, congestive heart failure, prior myocardial infarction, renal failure, diabetes, hypertension, chronic obstructive pulmonary disease or stroke, and cardiopulmonary bypass and aortic cross-clamp time. Twenty-five percent of patients (567/2299) were classified as obese. The results of the multivariate regression demonstrated that obesity was a risk factor only for superficial sternal wound infection (P < .001; odds ratio, 2.3), leg infections (P = .005; odds ratio, 1.8), and atrial dysrhythmias (P = .04; odds ratio, 1.2). Notably, obesity did not predispose toward increased pulmonary complications or deep sternal wound infection (P = .65). CONCLUSIONS: With the exception of superficial wound complications and atrial dysrhythmias, obesity is not a significant multivariate risk factor for adverse outcomes. The results indicate that obese patients may safely undergo cardiac surgery with due attention to technical considerations designed to minimize wound complications.

Adult↗
PubMed1996

Validation of the Edinburgh Postnatal Depression Scale (EPDS) in non-postnatal women.

This paper reports the validation of the EPDS against a Research Diagnostic Criteria diagnosis of Major and Minor depression. The EPDS was administered to non-postnatal women with older children (mean age of youngest child 3 years 9 months) and to postnatal women (baby aged 6 months). All who scored 9 or above and one third of low scorers were interviewed, using Goldberg's Clinical Interview Schedule. The study confirmed good user acceptability of the EPDS when administered as a postal questionnaire (92% response rate). The EPDS was found to have satisfactory sensitivity (79%) and specificity (85%). Our findings suggest that the EPDS take a place alongside other screening scales for depression in Community samples. It is proposed that when used in these settings it is referred to as the Edinburgh Depression Scale.

Depression, Postpartum↗
PubMed1996

Impact of clinical history and electrophysiologic characterization of accessory pathways on management strategies to reduce sudden death among children with Wolff-Parkinson-White syndrome.

OBJECTIVES: This study sought to determine whether the clinical and electrophysiologic criteria developed in adults also identify children with Wolff-Parkinson-White syndrome at risk for sudden death. BACKGROUND: In adults with Wolff-Parkinson-White syndrome, a shortest RR interval <220 ms during atrial fibrillation is a sensitive marker for sudden death. However, because reliance on the shortest RR interval has a low positive predictive value, the clinical history has assumed a pivotal role in assessing risk. This approach has not been evaluated in children. METHODS: We retrospectively evaluated 60 children </= 18 years old who underwent comprehensive electrophysiologic evaluation between 1979 and 1989 before undergoing operation for Wolff-Parkinson-White syndrome. Clinical and electrophysiologic data were analyzed after patients had been grouped by their clinical presentation: high risk (cardiac arrest), intermediate risk (syncope or atrial fibrillation) or low risk (orthodromic reciprocating tachycardia alone). RESULTS: Ten children had a clinical cardiac arrest (high risk); only one had a prior history of syncope or atrial fibrillation. Compared with the intermediate (n = 19) and low risk groups (n = 31), there were no differences in age ([mean +/- SD] 14.8 +/- 0.6 vs. 14.7 +/- 0.6 vs. 14.5 +/- 1.7 years), duration of symptoms (1.9 +/- 0.5 vs. 4.1 +/- 1.1 vs. 5.2 +/- .08 years), incidence of congenital heart disease (30% vs 26% vs 32%), presence of multiple pathways (20% vs 16% vs 16%) or accessory pathway location. A shortest pre-excited RR interval <220 ms was found in 7 of 7 high risk patients (sensitivity 100%), 14 of 19 intermediate risk patients and 11 of 31 low risk patients (prevalence 35%). CONCLUSIONS: Cardiac arrest was the only distinguishing clinical feature between high and low risk groups and the first manifestation in 80% of the children of an accessory pathway that can precipitate a life-threatening arrhythmia. In this series, the largest reported to date of children with Wolff-Parkinson-White syndrome having a cardiac arrest, a shortest pre-excited RR interval <220 ms was more sensitive than clinical history for identifying those at risk for sudden death.

Adolescent↗