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Continuous monitoring of pump performance is essential and effective for optimal driving of a pulsatile blood pump. The authors contrived a practical method for continuous estimation of blood volume in a pump by measurement of electrical impedance (Z). This method was evaluated with the air-driven, diaphragm type pump. The pump was made from polyurethane and had two metal connectors at the inlet and the outlet ports. Z was measured by charging the alternating current (50 kHz, 0.4 mA) between two connectors as electrodes. In in vitro tests, Z reached maximum value during full-empty and minimum value at full-fill. The blood volume calculated by an empirical equation of Z was linearly related to the real blood volume (r = 0.99). In in vivo tests with goats, pump output estimated by this method was linearly related to pump output measured with an electromagnetic flowmeter and effectively evaluated pump performance. For calibration, this method needed only to measure Z at full-fill. This method was useful as a controller of a full-fill to full-empty drive. It was concluded that this method is a practical estimate of pump performance, even if implantable diaphragm type pumps are used, and easily applicable to any kind of pulsatile pump.

Peripheral circulation (PC) during nonpulsatile (NP) perfusion is not satisfactorily understood, although it is known that animals can survive with chronic NP flow. In awake goats, PC was analyzed by hemodynamic and hormonal parameters, tissue blood flow of the ear measured by a noninvasive laser Doppler flowmeter, and distribution of the body surface temperature monitored by thermography. An NP systemic circulation was established in five 40-64 kg goats with a centrifugal pump (MD-10, Iwaki Pump, Japan) that replaced a pulsatile ventricular assist device 2 weeks postoperatively; this was done without anesthesia. Nonpulsatile total left heart bypass was obtained, with flow rates of 78-165 ml/kg/min. Systemic vascular resistance and blood adrenalin and noradrenalin levels were not affected by the depulsation. Tissue blood flow during NP perfusion was well maintained and showed comparable values to those during pulsatile systemic circulation. Vasomotion of 10-20 cycles/min was obvious in the tissue blood flow pattern, indicating adequate PC at each sampling point. Thermography before and after depulsation indicated no change of temperature distribution, and displayed warm peripheral areas. In conclusion, PC of animals on chronic NP systemic perfusion is adequately maintained.

In a previous article, a left ventricular assist system (LVAS) with a percutaneous transseptal cannulation technique for easy application was described. This system was safe and efficient (maximum output greater than 3 L/min) and fitted between the intraaortic balloon pumping and LVAS with thoracotomy. But technical skill for placement was slightly complicated. The cannulation system has been improved. In the new system, the inlet cannula is initially used as a sheath introducer and is quickly inserted into the left atrium after transseptal puncture. The new inlet cannula is made of polyvinyl chloride (TM100, Toyobo, Co., Ltd., Osaka, Japan), which has excellent antithrombogenicity and low friction using a polyester plasticizer. The distal part is designed to be flexible with a spiral wire for easy manipulation. A sealing hub was installed to prevent bleeding at the proximal The simplicity and safety of the new system were examined in chronic animal experiments. The inlet cannula was placed into the left atrium within a few seconds after transseptal puncture. During 20 days of activation, there were no episodes of systemic or pulmonary embolism, although no anticoagulant was used. Under fluoroscopy, there was no thrombus formation around the cannula at removal. On the 14th day after removal, the puncture site of the septum had healed. This system is ready for clinical use and shows promise of satisfactory safety and manageability.

The authors developed a novel hybrid system for long-term respiratory support with extracorporeal placental oxygenation. In this system, the patient's blood is oxygenated with O2 saturated artificial blood across the villous membrane during passage through the fetal circuit of the placenta, which is placed in a specially constructed artificial uterus. Human term placentas were obtained immediately after vaginal delivery and used for the experiments. The gas transfer performance of the current apparatus was 60 ml/min for O2 and 40 ml/min for CO2 at a blood flow rate of 1.0 L/min. From these results (and the assured blood compatibility of the placenta), the authors conclude that this system will become one of the most promising modalities for prolonged extracorporeal oxygenation.

In addition to the chromosome changes common to cancers, recent development of cytogenetics in human cancers has revealed, the site of specific chromosome changes which characterize specific cancers. Such cancer-specific aberrations are generally reciprocal translocations or deletions, and in some cases the translocations have been unequivocally demonstrated to involve cellular oncogenes (c-onc) in the new transcriptional control of other genes. Chromosome changes relatively common to cancers are amplification of specific genes by chromosome duplication or selective amplification as manifested by double minutes or homogeneously staining regions, and genome reorganization by nondisjunction, somatic recombination, polyploidization-segregation or other parasexual recombinations. The importance of such genome reorganization in cancer development was discussed in relation to the possible involvement of cellular escape mechanisms.