ECG Case of the Month: ECG in a 20-Year-Old Woman with Dyspnea. Sinus tachycardia (104 beats/minute), slight right axis deviation of the QRS (+92°), an R/S ratio greater than 1 in lead V1 with ST depression and T wave inversion in leads V1 - V4, and a prominent S wave in lead I, Q wave in lead III, and inverted T wave in lead III(S1 Q3 T3). These findings suggest right ventricular hypertrophy or strain and are consistent with pulmonary emboli.

A 20-year-old Hispanic woman presented to the emergency department complaining of six months of progressive dyspnea on exertion associated with intermittent palpitations. Her only past medical history was a stillbirth at 32 weeks gestation about two years ago. Her vital signs in the emergency department were a heart rate of 120 beats/minute, a blood pressure of 145/86 mmHg, and an arterial oxygen saturation of 98 percent with her breathing air. Significant laboratory values included a blood hemoglobin of 14.5 gm/dL, a hematocrit of 49 percent, a brain naturetic peptide (BNP) level of 177 pg/mL, a D-dimer level of 330 ng/ml, a prothrombin time of 12.85 s with an INR of 1.2, and a partial thromboplastin time of 45.7s. Urine pregnancy test was positive, and serum beta-human chorionic gonadotropin level was 81 MIU/mL consistent with a fetus of 3-4 weeks gestational age. An electrocardiogram was recorded.

Photoperiod alters phase difference between activity onset in vivo and mPer2::luc peak in vitro.

Photoperiod is a significant modulator of behavior and physiology for many organisms. In rodents changes in photoperiod are associated with changes in circadian period and photic resetting of circadian pacemakers. Utilizing rhythms of in vivo behavior and in vitro mPer2::luc expression, we investigated whether different entrainment photoperiods [light:dark (L:D) 16:8 and L:D 8:16] alter the period or phase relationships between these rhythms and the entraining light cycle in Per2::luc C57BL/6J mice. We also tested whether mPer2::luc rhythms differs in anterior and posterior suprachiasmatic nucleus (SCN) slices. Our results demonstrate that photoperiod significantly changes the timing of the mPer2::luc peak relative to the time of light offset and the activity onset in vivo. In both L:D 8:16 and L:D 16:8 the mPer2::luc peak maintained a more stable phase relationship to activity offset, while altering the phase relationship to activity onset. After the initial cycle in culture, the period, phase, and peaks per cycle were not significantly different for anterior vs. posterior SCN slices taken from animals within one photoperiod. After short-photoperiod treatment, anterior SCN slices showed increased-amplitude Per2::luc waveforms and posterior SCN slices showed shorter-duration peak width. Finally, the SCN tissue in vitro did not demonstrate differences in period attributable to photoperiod pretreatment, indicating that period aftereffects observed in behavioral rhythms after long- and short-day photoperiods are not sustained in Per2::luc rhythms in vitro. The change in phase relationship to activity onset suggests that Per2::luc rhythms in the SCN may track activity offset rather than activity onset. The reduced amplitude rhythms following long-photoperiod treatment may represent a loss of coupling of component oscillators.