Biomedical subjects

Mohammed N Khan

Publications and source records attributed to Mohammed N Khan.

4 recordsLinked to original sources

PubMed2006

Does Ramadan fasting affect expiratory flow rates in healthy subjects?

OBJECTIVE: To assess whether Ramadan fasting affects the expiratory flow rates in healthy subjects, and to know if these effects correlate to a change in other variables. METHODS: This unmatched case-control longitudinal study includes 46 non-smoking healthy subjects who undertook lung function testing at the Aga Khan University, Pakistan. Expiratory flow rates and body mass were measured in 3 Islamic months, corresponding to November 2001 to January 2002. RESULTS: There was a significant reduction in body mass in Ramadan compared to pre and post Ramadan. No significant changes in expiratory flows were seen during Ramadan as compared to the pre Ramadan period. However, forced expiratory flow rates at 75% of vital capacity (FEF(75)) and between 75% and 85% of vital capacity (FEF(75-85)) showed a significant increase in the post Ramadan period compared to Ramadan. Changes in FEF(75) were negatively correlated to changes in body mass between Ramadan and post Ramadan. CONCLUSION: This study shows that Ramadan fasting will not affect expiratory flow rates in healthy subjects. Post Ramadan values did show an increase in FEF(75) and FEF(75-85), possibly due to changes in body water and fat content. The reductions in body mass were most probably due to lack of nutrition and not dehydration as the fasts were performed in winter. Collection of reference values or early phase clinical trials measuring expiratory flow rates should not be affected by Ramadan fasting.

Adolescent↗

PubMed2005

Chronotropic incompetence as a predictor of death among patients with normal electrograms taking beta blockers (metoprolol or atenolol).

Chronotropic incompetence, or an inability to increase heart rate during exercise, independently predicts death in patients not taking beta blockers. Whether it predicts death in patients taking beta blockers is not known. Consecutive patients (n = 3,736; mean age 58 +/- 11 years; 68% men), who were taking either metoprolol tartrate or atenolol and were referred for symptom-limited exercise testing from 1990 to 2002 at a major academic medical center, formed the prospective study cohort. None had heart failure, pacemakers, atrial fibrillation, or any electrocardiographic abnormalities. Patients were followed for a median of 4.5 years for all-cause mortality. Chronotropic response was defined as the percentage of heart rate reserve used. A value of < or =62%, which was noted in 813 patients (22%), was considered abnormal, meaning that chronotropic incompetence was present. There were 173 deaths. After adjusting for age, gender, heart rate at rest, standard risk factors, other medications, Duke treadmill score, and heart rate recovery, chronotropic incompetence predicted death (adjusted hazard ratio 1.94, 95% confidence interval 1.43 to 2.64, p <0.0001). The association of chronotropic incompetence with death was present, irrespective of which drug was taken or the number of half-lives that had elapsed since the last dose. In conclusion, in patients taking beta blockers, chronotropic incompetence is independently predictive of death.

Adrenergic beta-Antagonists↗

PubMed2005

Delayed lead perforation: a disturbing trend.

BACKGROUND: Delayed lead perforation (occurring more than 1 month after implantation) is a rare complication. Its pathophysiology and optimal management are currently unclear. METHODS: Three cases of delayed lead perforation (6-10 month) were identified in patients with low-profile active fixation leads. RESULTS: All cases presented in a subacute fashion with pleuritic chest pain with confirmatory chest x-ray and device interrogation. Given the potential complications of a perforated lead, all cases had the lead extracted under TEE observation with cardiac surgery backup in the operating room. All patients tolerated extraction without complication. CONCLUSION: Based on these cases, we recommend a management scheme for patients who present with delayed lead perforation.

Adult↗

PubMed2003

Usefulness of the pediatric electrocardiogram in detecting left ventricular hypertrophy: results from the Prospective Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted HIV Infection (P2C2 HIV) multicenter study.

BACKGROUND: A shortcoming of the pediatric electrocardiogram (ECG) appears to be its inability to accurately detect left ventricular hypertrophy (LVH). This study prospectively assesses the usefulness of the pediatric ECG as a screening modality for LVH. METHODS: Concomitant echocardiograms and ECGs from a large cohort of children who were exposed to the human immunodeficiency virus (HIV; uninfected) and children who were infected with HIV were compared. By use of the values of Davignon et al, qualitative determination of LVH and quantitative criteria for LVH (RV6, SV1, RV6+SV1, QV6, and Q(III) >98% for age, R/SV1 <98% for age, and [-]TV6) were compared to body surface area adjusted for left ventricular (LV) mass z score. Results were then stratified according to weight and weight-for-height z scores. New age-adjusted predicted values were then constructed from children of a mixed race who were HIV-uninfected, < or =6 years old, and similarly assessed. RESULTS: The sensitivity rate was <20% for detecting increased LV mass, irrespective of HIV status; the specificity rate was 88% to 92%. The sensitivity rate of the individual criteria ranged from 0 to 35%; the specificity rate was 76% to 99%. Test sensitivities remained low when stratified by weight and weight-for-height z scores. Areas under the receiver operator characteristic curves were between 0.59 and 0.70, also suggesting poor accuracy of the ECG criteria. By use of new age-adjusted predicted values, the sensitivity rate decreased to <17%, and the specificity rate increased to 94% to 100%. CONCLUSION: The ECG is a poor screening tool for identifying LVH in children. Sensitivity is not improved with revision of current criteria.

Child, Preschool↗