PURPOSE: We performed invasive thermometry to verify the elevation of local temperature in the liver during hyperthermia. MATERIALS AND METHODS: Three 40-kg pigs were used for the experiments. Under general anesthesia with ultrasonography guidance, two glass fiber-optic sensors were placed in the liver, and one was placed in the peritoneal cavity in front of the liver. Another sensor was placed on the skin surface to assess superficial cooling. Six sessions of hyperthermia were delivered using the Celsius TCS electro-hyperthermia system. The energy delivered was increased from 240 kJ to 507 kJ during the 60-minute sessions. The inter-session cooling periods were at least 30 minutes. The temperature was recorded every 5 minutes by the four sensors during hyperthermia, and the increased temperatures recorded during the consecutive sessions were analyzed. RESULTS: As the animals were anesthetized, the baseline temperature at the start of each session decreased by 1.3degrees C to 2.8degrees C (median, 2.1degrees C). The mean increases in temperature measured by the intrahepatic sensors were 2.42degrees C (95% confidence interval [CI], 1.70-3.13) and 2.67degrees C (95% CI, 2.05-3.28) during the fifth and sixth sessions, respectively. The corresponding values for the intraperitoneal sensor were 2.10degrees C (95% CI, 0.71-3.49) and 2.87degrees C (1.13-4.43), respectively. Conversely, the skin temperature was not increased but rather decreased according to application of the cooling system. CONCLUSION: We observed mean 2.67degrees C and 2.87degrees C increases in temperature at the liver and peritoneal cavity, respectively, during hyperthermia. In vivo real-time thermometry is useful for directly measuring internal temperature during hyperthermia.
Anesthesia, General ; Animals ; Fever* ; Glass ; Liver* ; Peritoneal Cavity ; Skin ; Skin Temperature ; Swine ; Thermometry ; Ultrasonography

BACKGROUND AND OBJECTIVES: Prolonging of the corrected QT interval (QTc) has been reported after cardiac surgery in some studies. However, there have not been many studies on infant open cardiac surgery for ventricular septal defect (VSD) repair. This study was performed to define the changes in QTc and to find related post-surgery factors in this patient group. SUBJECTS AND METHODS: From 2008 to 2012, 154 infants underwent VSD repair at the Severance Cardiovascular Hospital. This study includes 105 of these cases. QTc was measured in these patients retrospectively. Demographic data and peri-procedural data, such as Aristotle score, cross-clamp time and bypass time, were analyzed. The exclusion criteria included multiple and small VSDs that underwent direct closure. RESULTS: Mean post-operative QTc was increased compared to the pre-operative measurements (from 413.6+/-2.3 to 444.9+/-2.5, p<0.001). In multiple linear regression, the comprehensive Aristotle score was associated with increasing QTc (p=0.047). The incidence of transient arrhythmia, such as atrial tachycardia, junctional ectopic tachycardia, premature atrial contraction, or premature ventricular contraction, was associated with QTc prolongation (p=0.005). Prolonged QTc was also associated with cross-clamp time (p=0.008) and low weight (p=0.042). Total length of stay at the intensive care unit and intubation time after surgery were not associated with QTc prolongation. CONCLUSION: Prolonged QTc could be seen after VSD repair in infants. This phenomenon was associated with peri-procedural factors such as the Aristotle score and cross-clamp time. Patients with QTc prolongation after cardiac surgery had an increased tendency towards arrhythmogenicity in the post-operative period.
Arrhythmias, Cardiac ; Atrial Premature Complexes ; Electrocardiography ; Heart Septal Defects, Ventricular* ; Humans ; Incidence ; Infant* ; Intensive Care Units ; Intubation ; Length of Stay ; Linear Models ; Retrospective Studies ; Tachycardia ; Tachycardia, Ectopic Junctional ; Thoracic Surgery ; Ventricular Premature Complexes