Toxicity of topical lidocaine applied to the breasts to reduce discomfort during screening mammography.

BACKGROUND: We measured the effect of 30 milliliters (mL) of 4% lidocaine gel on the breasts and chest wall of healthy women covered for 1 h on plasma concentrations of lidocaine and its principal metabolite, monoethylglycinexylidide (MEGX), electrocardiogram (EKG) results, and adverse events. MATERIALS AND METHODS: This institutional review board-approved, prospective, open-label study complied with the Health Insurance Portability and Accountability Act (HIPAA). The study evaluated 10 healthy women aged 42-75 years with 30 mL of 4% lidocaine gel on the skin of the breasts and chest wall covered for 1 h. Cardiac and neurological assessments were performed and blood was drawn for lidocaine and MEGX levels at baseline and 1/2, 1, 2, 3, 4, 6, and 8 h after application. EKGs were performed before application and at 3 h. Subjects provided informed written consent. Primary and secondary outcomes were plasma concentrations of lidocaine and MEGX and frequency of adverse events, respectively. Statistical analysis included paired t-tests for EKGs and repeated measures regression for vital signs. RESULTS: No lidocaine was detected in the blood of 9 of 10 subjects. One subject had low plasma concentrations of lidocaine just above the level of detection the first 4 h after application only. No MEGX was detected. Mean decrease in heart rate was likely multifactorial. CONCLUSION: Thirty mL of 4% lidocaine gel on the breasts and chest wall covered for 1 h in healthy women resulted in plasma concentrations of lidocaine and MEGX well below therapeutic or toxic levels and no clinically significant adverse events.

Echocardiography improves detection of rejection after heterotopic mouse cardiac transplantation.

BACKGROUND: Current assessments of cardiac rejection in murine transplant models rely on subjective estimates of the force of the palpable heart beat that have limited sensitivity and precision. METHODS: We used 2-dimensional echocardiography to evaluate changes in left ventricular posterior wall thickness (PWT) in a heterotopic cardiac mouse transplant model of rejection. Nine allografts and 6 isografts were imaged daily for 6 days and harvested. Thirteen allografts were imaged daily and harvested at day 3. RESULTS: Intraobserver variability on PWT was 0.003 +/- 0.09 mm, interobserver variability 0.09 +/- 0.11 mm. Allograft PWT increased after transplantation (0.74 +/- 0.02 mm to 1.28 +/- 0.05 mm at day 5, P <.0001). For isografts, PWT remained constant (0.73 +/- 0.03 mm to 0.85 +/- 0.01 mm) after an initial increase at day 1. Palpation failed to identify rejection at day 3 whereas PWT was already increased (1.15 +/- 0.02 mm in the allografts at day 3 vs 0.85 +/- 0.02 mm in the isografts, P <.0001). There was a relation between histologic score and PWT (P <.0001). CONCLUSION: Two-dimensional echocardiography allows the noninvasive detection and follow-up of cardiac rejection after transplantation. It eliminates the subjectivity of palpation and provides quantitative and reliable indices of rejection.