Complications after cryosurgery with new miniature cryoprobes in long hollow bones: an animal trial.

BACKGROUND: In vitro studies show that new miniature cryoprobes are suitable for cryoablation of bone tissue. The aim of this animal trial on 24 sheep was to examine the perioperative complications, particularly the danger of embolism, of cryoablation when using miniature cryoprobes. METHODS: Cryoablations with 2 freeze-thaw cycles each were carried out in the epiphysis of the right tibia and the metaphysis of the left femur. Pulmonary artery pressure (PAP) and central venous pressure (CVP) were measured. Throughout the intra- and perioperative phase, heart rate and oxygen saturation by pulse oxymetry, blood gas and electrolytes were monitored regularly. Postoperative complications were examined up to 24 weeks postoperative. RESULTS: As result, no significant increase of PAP, CVP or heart rate were observed. Blood gases were unremarkable, with pO2 and pCO2 remaining constant throughout the operation. Regarding pH, standard bicarbonate and base excess, only a non-significant shift towards a slight acidosis was seen. There was a mean hemoglobin decrease of 0.5 g/dl. One animal showed postoperative wound infection and wound edge necrosis. No major peri- and postoperative complications associated with cryosurgery of bone were observed, especially regarding clinically relevant pulmonary embolism. CONCLUSION: Surgery with new types of miniature cryoprobes appears to be a safe alternative to or a complement to conventional resection of abnormal bone tissue.

Effect of the Na+/H+ exchange inhibitor eniporide on cardiac performance and myocardial high energy phosphates in pigs subjected to cardioplegic arrest.

BACKGROUND: Pharmacologic Na(+)/H(+) exchange inhibition has been suggested to ameliorate cardiac performance depression associated with myocardial ischemia/reperfusion. The purpose of our experimental study was to investigate the impact of the novel Na(+)/H(+) exchange inhibitor Eniporide (EMD 96785) on cardiac performance and high energy phosphate content in a clinically relevant pig model of cardioplegic arrest. METHODS: We subjected 21 pigs (47 +/- 12 [SD] kg) to cardiopulmonary bypass (CPB) and 60 minutes cold (4 degrees C) crystalloid cardioplegic arrest (Bretschneider). The pigs were randomized to receive either systemic infusion of 3 mg/kg Eniporide before cardioplegia with added 2 micromol/L Eniporide (ENI-CP+iv; n = 7); 3 mg/kg Eniporide in cardioplegia only (ENI-CP; n = 7); or no Eniporide (control; n = 7). For cardiac performance determination we measured preload recruitable stroke work and Tau, the time constant of left ventricular (LV) isovolumic relaxation using sonomicrometry and micromanometry before CPB as well as 30, 60, and 120 minutes after weaning off CPB. LV and right ventricular myocardial adenine nucleotides (ATP, ADP, and AMP), glycogen, and water content were determined at the end of the experiments. RESULTS: Neither for standard hemodynamics including vascular pressures and cardiac index nor for cardiac performance factors did we find statistically significant differences between the groups. Similarly, myocardial adenine nucleotides, glycogene, and water content did not differ significantly between the groups. CONCLUSIONS: In this acute study we did not find significant effects of the Na(+)/H(+) exchange inhibitor Eniporide on cardiac performance and high energy phosphate content in healthy pig hearts subjected to ischemia/reperfusion induced by crystalloid cardioplegic arrest.

The use of a new miniature cryoprobe for ablation of bone tissue: in vivo assessment of the probe and application of the method to bone in a sheep model.

BACKGROUND: So far, modern miniature cryoprobes were used for local destruction of soft tissue tumours without damaging the adjacent healthy tissue. In this study, cryoablation methodology was applied to bone and the cooling capacity of the probe was examined in vitro and in vivo. METHOD: Freezing was performed by cooling one or two probes (diameter 3.2 mm) to -180 degrees C with liquid nitrogen. The cooling capacity of the probes was determined optically and thermally against a homogeneous reference gel, followed by in vivo measurements on femoral and tibial sheep bone followed by histological examination. RESULTS: Thanks to the synergistic effect, the simultaneous use of 2 probes produced an almost spherical expansion of cold in the homogenous gelatin. During the in vivo freezes, the temperature curves showed a more moderate trend. Nevertheless, due to the synergistic effect, temperatures below -50 degrees C could be reached at a distance of 1 cm from the probe. No local or systemic intraoperative complications were observed. Histological examination revealed cell necrosis up into the -10 degrees C isotherm. CONCLUSIONS: Adequate tissue cooling of the bone matrix can be achieved with in vivo freezes by means of one or more miniature cryoprobes. Therefore, this probe could provide an alternative to or supplement surgical resection of pathological bone processes.