Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 +/- 2.9 J) than for the transvenous lead system (9.5 +/- 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 +/- 7.4 omega to 39.2 +/- 5.0 omega. In the frontal plane, the interelectrode area increased by 11.3% +/- 5.5% (P < 0.0001) and in the lateral plane by 29.5% +/- 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow-up. Complications with the subcutaneous electrode were not observed during a follow-up of 15.8 +/- 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.

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O Ob bj je ec ct ti iv ve es s: : Acute renal failure (ARF) is a common complication following open heart surgery especially in infants. Effects of blood viscosity on renal function are well known, but have not been investigated in cardiopulmonary bypass (CPS) as yet.M Ma at te er ri ia al l a an nd d m me et th ho od ds s: : We investigated blood viscosity and different markers of glomerular and tubular renal function in a group of 37 infants below 18 month of age, receiving CPS surgery for different diagnoses.In an experimental setting, we investigated 28 isolated pig-kidneys with different hematocrits in an autologous blood perfused model. R Re es su ul lt ts s: : In infants, creatinine clearance decreased and urinary excretion of albumin and β-NAG increased during the aortic cross clamp time (AT) and during the first hours following operation, indicating moderate glomerular and tubular damage. During AT, blood was hemodiluted to a hemoglobin of 8.4 ± 0.4 g/dl. Thus, blood viscosity during AT and hypothermia was slightly below pre-CPB values. Lower blood viscosity was related to less renal damage (P < 0.01).In isolated pig-kidneys, group I (n = 14) was perfused with a hemoglobin of 10.2 ± 0.3 g/dl and group II (n = 14) was hemodiluted to 6.5 ± 0.9 g/dl. Group II kidneys showed lower vascular resistance, elevated creatinine clearance, elevated oxygen consumption and elevated sodium reabsorption (P < 0.05).C Co on nc cl lu us si io on ns s: : Reducing blood viscosity below physiological values improves tubular as well as glomerular function under CPB conditions. Thus we hold hemodilution to be an appropriate method for optimizing CPB procedures. O Ob bj je ec ct ti iv ve e: : The hemocompatibility of oxygenators (OX) can be improved by coating of blood contact surfaces with biopolymers. In the new Trillium (TR) coating of the Affinity hollow-fiber OX, the blood-OX interaction was attempted to reduce by using two structurally different polymer layers. The aim of this in-vitro experiment was the comparison of both physical properties and hemocompatibility of TR-coated OX with the uncoated (UC) and AOThel-coated (AO) versions.M Me et th ho od d: : For the experiment, three standardized circuits used, each with a roller-pump (flow rate:5 l/min) and a separate reservoir. The priming volume was a mixture of fresh, heparinized (100 IE/ml) human blood and Ringer's lactate solution (Hb: 8.0 g/dl). During a 180-min total circulation time, the blood temperature was reduced from 37°C to 20°C for 30 min after 120 min of per fusion. At the beginning and every 30 min of the circulation, blood count, free Hb, thrombocytic hemostasis (tPA, d-dimer, prothrombin fragments F1+2, TAT), PMN-elastase and complements C3c + C5a determined. In addition, the pressure drop was obtained. Scanning electron microscopic images of fibers, heat exchangers and OXhousing were performed after completing the experiment.R Re es su ul lt ts s: : The biggest pressure drop was in TR and lowest in UC. The latter showed the lowest hemolysis ratio; howeve...

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