Age-related differences of intraischemic gap junction uncoupling in hearts during ischemia.

OBJECTIVE: Myocardial ischemia leads to energetic, morphologic, metabolic, and functional alterations. To evaluate differences in ischemia tolerance between neonatal and adult hearts, we investigated gap junction uncoupling (GJU) and its correlation to myocardial intracellular edema formation during normothermic ischemia. METHODS: Hearts of landrace piglets (neonates, 7.4 ± 1.9 days of age, body weight 2.9 ± 0.5 kg, n = 5 and adults, 84 ± 9 days of age, body weight 30.5 ± 3.9 kg, n = 5) were investigated. After we harvested the hearts, the bioelectrical impedance spectra were measured continuously during normothermic global ischemia (35°C). Spectra of the dielectric permittivity, ε'(frequency), and conductivity, σ(frequency), were calculated from the impedance measurements, and GJU was identified in the sigmoidal time course of ε' (13 kHz). The extracellular volume was estimated by the ratio σ (100Hz)/σ (1MHz). Dielectric data were correlated with electron-microscopical images. RESULTS: Intraischemic GJU was observed in neonates after 54 ± 9 minutes of ischemia and thus significantly earlier than in adults (90 ± 7 minutes, P < .05). A more than 20% increase of intercalated water was found in tissue samples of neonates after 20 ± 2 minutes, in contrast to adults after 137 ± 8 minutes (P < .05). CONCLUSIONS: Intraischemic formation of edema and earlier GJU indicate faster intraischemic changes in neonates compared with adults. Intraischemic GJU and determination of intracellular water shifts are an experimental approach to establish the period of life-threatening damage. Because both parameters are linked and occur significantly earlier in neonates, they distinctly demonstrate the lower ischemia tolerance of neonatal hearts as both events interact.

Quality of life after replacement of the ascending aorta in patients with true aneurysms.

True aneurysms of the ascending aorta often remain undetected, yet their sequelae carry a high rate of mortality and morbidity. The operative risk of nonemergent replacement of the ascending aorta is low. It is important to consider quality of life in determining the most appropriate treatment for patients who have aneurysms but have not yet experienced major complications.From January 1999 to December 2003, 134 consecutive patients underwent replacement of a dilated ascending aorta at our center. Another 124 patients with acute or chronic aortic dissections, aortic rupture, or intramural hematoma were excluded. Standard SF-36 and general health questionnaires were sent to all 124 survivors who could be traced. Follow-up was 98.4% complete. The mean age of the survivors was 61.7 +/- 11 years, and 63.4% were men. Operative procedures consisted of supracoronary replacement of the ascending aorta in 35.9%, the Wheat procedure in 44%, the David procedure in 11.2%, the Bentall-DeBono procedure in 9%, and the Cabrol procedure in 2.2%. Patients were monitored until May 2005.Thirty-day and midterm mortality rates were 3.7% and 3.9%, respectively. Morbidity due to stroke was 6%, to bleeding 6%, and to myocardial infarction 4.4%. Postoperative quality-of-life evaluation revealed many subscales of SF-36 that were below the norm when compared with a standard population in physically dominated categories.Replacement of the dilated ascending aorta carries acceptable risk in regard to operative death and postoperative quality of life, although this last showed some decline in comparison with quality of life in a normal, healthy population.