Biomedical subjects

R Ammar

Publications and source records attributed to R Ammar.

At least 37 records · Page 2Linked to original sources

PubMed2001

An evaluation of the change in electrocardiographic P-wave variables after acute caffeine ingestion in normal volunteers.

BACKGROUND: Caffeine's effect on supraventricular dysrhythmias is poorly understood, and establishing a marker to predict atrial fibrillation may help to explain supraventricular dysrhythmias caused by caffeine. OBJECTIVE: To evaluate the effects of caffeine (mean 6.1 mg/kg) on maximum P-wave duration and P-wave dispersion in normal volunteers. METHOD: A randomised, double-blind, placebo-controlled, crossover study in 10 healthy volunteers at least 17 years of age at the University of Connecticut. Participants abstained from caffeinated products for at least 2 days before study initiation and were randomly allocated on different days to receive placebo or caffeine 400 mg. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG was performed 3 h after ingesting the study drug. RESULTS: No significant changes were found within intra- or intergroup comparisons for any P-wave variables measured. CONCLUSION: Single dose caffeine (400 mg) does not affect average P-wave duration, maximum P-wave duration or P-wave dispersion in normal individuals.

Adult↗

PubMed2001

Evaluation of electrocardiographic and hemodynamic effects of caffeine with acute dosing in healthy volunteers.

STUDY OBJECTIVE: To evaluate the effects of moderate, single-dose caffeine consumption on electrocardiographic variables: PR, QRS, QT, QTc, and RR intervals, and QT and QTc interval dispersion. Effects of caffeine on blood pressure and heart rate also were evaluated. DESIGN: Randomized, double-blind, placebo-controlled, crossover study. SETTING: University school of pharmacy. PATIENTS: Ten healthy volunteers aged 17 years or older. INTERVENTION: Participants abstained from caffeinated products for at least 2 days before the study began and were randomly designated to receive placebo or caffeine 400 mg on various days. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG performed 3 hours after ingesting the study drug. Blood pressure readings were taken with each ECG. MEASUREMENTS AND MAIN RESULTS: No significant changes in any intragroup or intergroup electrocardiographic variables occurred. Caffeine increased blood pressure (systolic blood pressure [SBP]/diastolic blood pressure [DBP]) from 118+/-5/75+/-6 mm Hg to 128+/-8/77+/-7 mm Hg versus baseline (p=0.0022 and p=0.0368 for SBP and DBP, respectively). After drug dosing, SBP in the caffeine group was significantly higher than in the placebo group (128+/-8 mm Hg versus 119+/-7 mm Hg, p=0.0174). CONCLUSION: Moderate caffeine consumption by healthy young adults does not acutely affect PR, QRS, QT, QTc, and RR intervals, or QT and QTc interval dispersion. Caffeine-naive subjects experienced persistent elevations in SBP and DBP 3 hours after caffeine ingestion, indicating that longer caffeine abstinence than that which is recommended is necessary for blood pressure determination in the clinical setting.

Administration, Oral↗

PubMed2000

Measurements of the mass, total width, and two-photon partial width of the eta(c) meson.

Using 13.4 fb(-1) of data collected with the CLEO detector at the Cornell Electron Storage Ring, we have observed 300 events for the two-photon production of ground-state pseudoscalar charmonium in the decay eta(c)-->K(0)(S)K-/+pi(+/-). We have measured the eta(c) mass to be [2980.4+/-2.3 (stat)+/-0.6 (syst)] MeV and its full width as [27.0+/-5.8 (stat)+/-1.4 (syst)] MeV. We have determined the two-photon partial width of the eta(c) meson to be [7.6+/-0.8 (stat)+/-0.4 (syst)+/-2.3 (br)] keV, with the last uncertainty associated with the decay branching fraction.

Journal Article↗

PubMed2000

Search for the decay &Bmacr;(0)-->D(*0)gamma

We report results of a search for the rare radiative decay &Bmacr;(0)-->D(*0)gamma. Using 9.66x10(6) B&Bmacr; meson pairs collected with the CLEO detector at the Cornell Electron Storage Ring, we set an upper limit on the branching ratio for this decay of 5.0x10(-5) at 90% C.L. This provides evidence that the anomalous enhancement is absent in W-exchange processes and that weak radiative B decays are dominated by the short-distance b-->sgamma mechanism in the standard model.

Journal Article↗

PubMed2000

Coping strategies, life style changes, and pessimism after open-heart surgery.

A mail questionnaire was completed by 171 patients two to 20 months after undergoing coronary artery bypass graft surgery (CABG). The post-CABG period was characterized by fewer working hours, a higher level of physical exercise, a reduction in smoking, and more appropriate nutritional habits, compared with the preoperation period. At the same time, the anxiety level of post-CABG patients was higher than that measured in a community sample. Post-CABG high psychological distress (anxiety and mood states) and low functional capacity were associated with high levels of pessimism and ineffective emotion-focused coping strategies. These results may be used by social workers in devising psychological interventions aimed at improving post-CABG patients' quality of life and bolstering their coping strategies.

Adaptation, Psychological↗

PubMed2000

Forced-air warming decreases vasodilator requirement after coronary artery bypass surgery.

Postoperative hypothermia is common and associated with adverse hemodynamic consequences, including adrenergically mediated systemic vasoconstriction and hypertension. Hypothermia is also a known predictor of dysrhythmias and myocardial ischemia in high-risk patients. We describe a prospective, randomized trial designed to test the hypothesis that forced-air warming (FAW) provides improved hemodynamic variables after coronary artery bypass graft. After institutional review board approval and written informed consent, 149 patients undergoing coronary artery bypass graft were randomized to receive postoperative warming with either FAW (n = 81) or a circulating water mattress (n = 68). Core temperature was measured at the tympanic membrane. A weighted mean skin temperature was calculated. Heart rate, mean arterial blood pressure, central venous pressure, cardiac output, and systemic vascular resistance were monitored for 22 h postoperatively. Mean arterial blood pressure was maintained by protocol between 70 and 80 mm Hg by titration of nitroglycerin and sodium nitroprusside. The two groups had similar demographic characteristics. Tympanic and mean skin temperatures were similar between groups on intensive care unit admission. During postoperative rewarming, tympanic temperature was similar between groups, but mean skin temperature was significantly greater in the FAW group (P < 0.05). Heart rate, mean arterial pressure, central venous pressure, cardiac output, and systemic vascular resistance were similar for the two groups. The percent of patients requiring nitroprusside to achieve the hemodynamic goals was less (P < 0.05) in the FAW group. In conclusion, aggressive cutaneous warming with FAW results in a higher mean skin temperature and a decreased requirement for vasodilator therapy in hypothermic patients after cardiac surgery. This most likely reflects attenuation of the adrenergic response or opening of cutaneous vascular beds as a result of surface warming. IMPLICATIONS Forced-air warming after cardiac surgery decreases the requirement for vasodilator drugs and may be beneficial in maintaining hemodynamic variables within predefined limits.

Aged↗

PubMed1999

Same-day combined coronary angioplasty and minimally invasive coronary surgery.

Integrated myocardial revascularization combines the advantages of angioplasty, stenting, and minimally invasive surgery to revascularize patients with multivessel coronary artery disease without cardiopulmonary bypass. This pilot study showed that a new same-day management strategy, consisting of percutaneous coronary intervention followed immediately by minimally invasive surgery, was feasible and provided complete all-arterial revascularization with minimal surgical trauma, short hospital stay, and excellent early therapeutic result in 14 patients with multivessel coronary disease.

Aged↗

PubMed1999

Anomalous origin of the left main coronary artery: anatomical correction and concomitant LIMA-to-LAD grafting.

A 55-year-old woman with angina pectoris and exertional dyspnea underwent surgical correction of an anomalous left main coronary artery (LMCA) originating from the right sinus of Valsalva. During the operation, the roof of the intramurally coursing LMCA was opened into the aortic lumen, and a neo-coronary ostium was created by suturing the circumference of the LMCA intima to the aortic intima. In addition, a left internal mammary artery (LIMA) to left anterior descending (LAD) coronary artery anastomosis was performed. Post-operative coronary angiography demonstrated two independent, patent orifices of both the LMCA and the right coronary artery. The technique presented herein, of combined anatomical correction and LIMA-to-LAD grafting, is feasible and leads to distinct angiographic and clinical improvement.

Cardiopulmonary Bypass↗

PubMed1998

Partial breast necrosis after MIDCABG via small anterolateral thoracotomy.

We report a case in which partial breast necrosis developed after minimally invasive direct coronary artery bypass grafting using an IMA Retractor (Cardio-Thoracic Systems Inc, Cupertino, CA). We suggest that during minimally invasive direct coronary artery bypass grafting in the presence of a large breast, it is advisable to reduce the intraoperative additive forces of pressure and traction caused by the retractor arm on the breast tissue, thus avoiding further excessive compression on the partially compromised blood circulation of the breast.

Breast↗

PubMed1998

Utility of spiral CT in minimally invasive approach for aortic valve replacement.

OBJECTIVE: Several surgical approaches exist for a minimally invasive replacement of the aortic valve. A great concern exists about the variable exposure of the aortic root. We suggest the use of spiral CT as a non-invasive method for accurate determination of aortic annulus position. METHODS: Three patients scheduled for minimally invasive aortic valve replacement underwent chest spiral CT, (Select SP, Elscint, Haifa, Israel). Scanning was performed during breath holding using 5-mm thick slices, reconstructed every 2 mm (3 mm overlap), and a 1.5 pitch. Average scanning time was 30 s. No intravenous contrast media was used. Multiplannar and 3D images were reconstructed, using an Omnipro work station (Elscint LTD, Haifa, Israel). The position of the aortic valve annulus, in relation to the anterior chest wall was defined on these images. RESULTS: In all patients, the length and location of the incision were determined by the preoperative measurements. The location of the aortic valve was found highly correlative to the preliminary study. There was no need to extend the length of the incision, or change the surgical approach. CONCLUSIONS: We find spiral CT scanning enables accurate pre-operative anatomical assessment. This assessment, provides the surgeon with the advantage of preliminary planning of the appropriate approach for minimally invasive aortic valve replacement.

Aortic Valve↗

PubMed1996