The effect of 0.5 L 6% hydroxyethyl starch 130/0.42 versus 1 L Ringer's lactate preload on the hemodynamic status of parturients undergoing spinal anesthesia for elective cesarean delivery using arterial pulse contour analysis.

PURPOSE: Fluid loading attenuates the hypotensive response to spinal anesthesia (SA). This study aimed to compare the preload efficacy of 0.5 L hydroxyethyl starch (HES) versus 1 L Ringer's lactate (R/L) in the prevention of hypotension after SA for elective cesarean delivery (CD). Assessment of maternal hemodynamic variables using FloTrac/Vigileo™ and neonatal outcome constituted secondary outcomes. METHODS: Thirty-two ASA I/II parturients scheduled for elective CD were preloaded with either 1 L R/L (Group R/L, n = 16) or 0.5 L HES 6% 130/0.42 (Group T, n = 16) approximately 25 min before SA. Hypotension, defined as a 20% decrease of systolic arterial pressure (SAP) from baseline or SAP <100 mmHg, was treated with vasopressors according to a predetermined algorithm. The overall duration of hypotensive episodes and the total amount of vasopressors administered determined the severity of the hemodynamic instability. RESULTS: The incidence of hypotension was 73.3% in Group R/L and 46.7% in Group T. HES compared to R/L preload was associated with a shorter overall duration of hypotensive episodes (p < 0.001), a significantly less usage of ephedrine and phenylephrine (p = 0.015 and p = 0.029, respectively) and a greater impact, although not statistically significant, on cardiac index (CI) and stroke volume index (SVI). Although no statistical difference was detected between groups over time, there was a significant drop in CI, SVI and SAP within groups (p < 0.001) up to 14 min after SA. No difference was recorded in neonatal outcome. CONCLUSIONS: Preloading with 0.5 L HES 130/0.42 produced more stable hemodynamics compared to 1 L R/L solution in obstetric patients.

Ultrasonographic evaluation of abdominal organs after cardiac surgery.

BACKGROUND: Disturbances of the hepatosplanchnic region may occur after cardiac operations. Experimental studies have implicated impairment of splanchnic blood supply in major abdominal organ dysfunction after cardiopulmonary bypass (CPB). We investigated the impact of the cardiac operation and CPB on liver, kidney, and renal perfusion and function by means of ultrasonography and biochemical indices in a selected group of cardiac surgery patients. MATERIALS AND METHODS: Seventy five patients scheduled for a major cardiac operation were prospectively included in the study. Criteria for selection were moderate or good left ventricular ejection fraction and absence of previous hepatic or renal impairment. Ultrasound examination of the hepatic and renal vasculature and examination of biochemical parameters were performed on the day preceding the operation (T0), on the first postoperative day (T1), and on the seventh postoperative day (T2). RESULTS: Portal vein velocity and flow volume increased significantly, whereas hepatic artery velocity and flow volume decreased at T1 in comparison with T0. Hepatic vein indices remained unaffected throughout the observation period. Renal artery velocity and flow decreased, whereas renal pulsatility index and renal resistive index increased at T1 as compared with T0. Aspartate aminotransferase and alanine aminotransferase values were increased as compared with baseline values 24 h postoperatively. All parameters displayed a trend to approach preoperative levels at T2. Strong negative correlations between alanine aminotransferase values at T1 and hepatic artery velocity and flow volume at the same time point were also demonstrated (R = 0.638, P < 0.001 and r = 0.662, P < 0.001, respectively). CONCLUSIONS: The increase in portal vein flow and velocity and the decrease in hepatic artery flow and velocity in the period after CPB might be attributed to the hypothermic bypass technique and the hepatic arterial buffer response, respectively. The decrease in renal blood flow and velocity and the parallel increase in Doppler renal pulsatility index and renal resistive index could be considered as markers of kidney hypoperfusion and intrarenal vasoconstriction. Maintaining a high index of suspicion for the early diagnosis of noncardiac complications in the period after CPB and institution of supportive care in case of compromised splanchnic perfusion are warranted.

The use of the multi-electrode duty-cycled radiofrequency ablation catheter PVAC for the ablation of a left atrial tachycardia.

The multi-electrode ablation catheter PVAC is used to simplify pulmonary vein isolation in patients undergoing ablation of atrial fibrillation. The use of the PVAC in cases of atrial tachycardia has not been reported before. In the present report, we present the use of the PVAC for the ablation of a left atrial tachycardia following pulmonary vein isolation. This case may suggest that the PVAC could ablate some atrial tachycardias without any adjunctive ablation catheter, given its ability to map, pace and apply energy over a relatively broad area.

Low-dose (1 microg/kg) clonidine premedication and hypotension after carotid artery surgery.

We investigated the role of low-dose clonidine intravenous (IV) premedication in arterial pressure variation during and after carotid endarterectomy (CEA). A total of 84 patients, American Society of Anesthesiologists (ASA) II-III, scheduled for elective CEA under general anesthesia participated in this study. The patients were divided into 2 groups: group P (n = 42) and group C (n = 42) and received N/S 0.9% (placebo) or clonidine 1 µg/kg IV, respectively, 15 minutes before induction of anesthesia. Recovery times, number of patients needed to be treated for circulatory events (hypertension, hypotension, and bradycardia), number of circulatory events per patient, and consumption of vasoactive drugs (nitroglycerine, phenylphrine, and atropine) intraoperatively and the first 6 hours postoperatively were recorded. Significantly less hypertensive episodes were observed intraoperatively, but more hypotensive episodes were observed postoperatively in patients receiving clonidine. Intravenous premedication with low-dose clonidine (1 µg/kg) seems to be effective in preventing hypertensive episodes during CEA under general anesthesia but seems to increase the incidence of hypotension postoperatively.

Circulating matrix metalloproteinase 3 due to myocardial ischemia.

BACKGROUND: Experimental data suggest that matrix metalloproteinases (MMPs) such as MMP-3 have a central role in the remodeling period after a myocardial infarction (MI). The aim of this study was to use an experimental small-animal model to investigate the fluctuation in MMP-3 levels occurring in vivo after an acute MI. METHODS: We studied 13 New Zealand white rabbits weighing between 3 and 4 kg. After anesthetizing the animals, we performed a tracheotomy and induced an acute MI in 10 of the animals by occluding the left anterior descending coronary artery for 45 minutes. The remaining 3 rabbits constituted the control group. Three hours after reperfusion, blood samples were taken for biomedical analyses. RESULTS: Three hours after the artificially induced acute MI, serum MMP-3 levels were decreased by almost 50%. Cardiac troponin I (cTnI) concentrations were increased greatly (90-fold) after MI, further validating the efficiency of our experimental in vivo model of acute MI. CONCLUSION: Combining the data, we demonstrated that acute MI caused an early reduction in MMP-3 levels. The range of MMP-3 reduction is limited compared with other factors predicting MI, such as cTnI, which increases its usefulness. We demonstrated, however, that plasma fluctuation in MMP-3 levels could be used as a supplementary independent predictor of cardiovascular events in patients with stable coronary artery disease. This acute MI model used in our controlled setting proved to be a reliable and safe method for conducting in vivo studies.

Ventricular arrhythmias and antioxidative medication: experimental study.

INTRODUCTION: Reperfusion arrhythmias could be due to free radicals, while contraction excitation feedback is the cause of arrhythmias generated by blood pressure elevation (BPE). The aim of this study was to test the antiarrhythmic effects of an antioxidant (vitamin C [vit C], 1.5 g), an iron-binding agent (deferoxamine [Def], 1 g), and their combination in an experimental model of arrhythmia based on these 2 mechanisms. METHODS: Thirty anaesthetised sheep were divided into 4 groups, depending on the infused agent: saline (8 sheep), combination of vit C and Def (8), Def (6), and vit C (8). Induction of ventricular arrhythmias was attempted in all animals using both ischaemia-reperfusion (phase I) and a combination of ischaemia and BPE (phase II). In all cases ischaemia was caused by ligating the left anterior descending coronary artery distally to the origin of the 1st diagonal artery, while reperfusion was achieved by releasing the ligation 45 min later. BPE was achieved by obstructing the ascending aorta or by administering intravenous metaraminol. All agents were infused intravenously for 15 min and their administration was started 30 min after the first ligation. Phases I and II lasted 50 and 20 min, respectively. RESULTS: Ventricular tachycardia/fibrillation (VT/VF) was induced in all animals in the control group (8/8) and in the Def group (6/6). VT/VF appeared in 6/8 of the animals in the vit C group (75%) and in only 3/8 of the animals in the combination therapy group (37.5%). The difference between the combination and control groups was statistically significant (p < 0.03). CONCLUSIONS: The intravenous administration of vit C and Def in combination protects against VT/VF induced by ischaemia-reperfusion and/or BPE. Administration of Def alone does not appear to help, while the action of vit C alone is not clear.

Effects of mannitol in the prevention of lipid peroxidation during liver resection with hepatic vascular exclusion.

STUDY OBJECTIVE: To examine the efficacy of mannitol in the prevention of lipid peroxidation during major liver resections performed during hepatic inflow occlusion. DESIGN: Prospective, randomized, open-label study. SETTING: Aretaieion Hospital, a university-affiliated hospital. PATIENTS: 30 ASA physical status II and III patients, less than 75 years of age, scheduled for elective liver resection. INTERVENTIONS: All patients received combined general and epidural anesthesia. Laparotomy was performed through a bilateral subcostal incision, and hepatectomy was performed by inflow vascular exclusion (Pringle's maneuver). Before this maneuver, and if the patients were hemodynamically stable, they were randomized to receive either mannitol 20% 1.5 mL kg(-1) (group M) or normal saline 1.5 mL kg(-1) (group S) intravenously for 30 minutes. MEASUREMENTS: Venous blood malondialdehyde (MDA) concentration, as an index of lipid peroxidation, was measured spectrophotometrically at selected time points. MAIN RESULTS: Patients in both groups presented with raised MDA values (P < 0.05) for the period starting before the release of vascular occlusion until 6 days postoperatively. In patients receiving mannitol, lower MDA values were observed (P < 0.05) compared with group S at the end of operation. CONCLUSION: Mannitol has an antioxidant activity, but we were unable to confirm a positive impact on the postoperative clinical course.

Intrapericardial drug delivery: pharmacologic properties and long-term safety in swine.

BACKGROUND: Intrapericardial drug delivery is a promising new technique, but the pharmacologic properties of various agents delivered via this route are not known. Furthermore, the long-term safety of intrapericardial catheters has not been previously examined. METHODS: Using a pericardial access device, a catheter connected to a drug-delivery system was implanted in five pigs. Plasma levels and electrocardiographic measurements were obtained after intravenous and intrapericardial administration of digoxin and procainamide. Histological examination was performed after the device had been implanted for a total of 6 months. RESULTS: The QTc interval did not change significantly after digoxin or procainamide intravenous administration. QTc decreased by 47+/-23 ms (p=0.046) 8 h after digoxin intrapericardial administration and increased by 128+/-60 ms (p=0.002) 1 h after procainamide intrapericardial administration. The QRS duration did not change significantly after intravenous administration of either agent, but it increased by 17+/-9 ms (p=0.004) 1 h and by 15+/-4 ms (p=0.01) 8 h after procainamide intrapericardial administration. After intravenous procainamide the RR interval decreased, but it did not change significantly after intrapericardial administration of either agent. Histology showed moderate inflammatory infiltration and fibrosis adjacent to the catheter. CONCLUSIONS: Intrapericardial delivery of digitalis and procainamide produces unique electrophysiological properties. In contrast to satisfactory success of the implantation technique, long-term dwell of the catheter in the pericardium induces moderate, albeit probably clinically significant, fibrosis.

Distribution of killer cell immunoglobulin-like receptors in the Greek population.

The interaction between killer cell immunoglobulin-like receptors (KIR) expressed on natural killer (NK) cells, and human leukocyt antigen (HLA) molecules expressed on target cells is known to regulate the cytolytic activity. A wide range of KIR genotypes is observed in the population, as the number of KIR loci can vary. In the present study we have determined the frequencies and combinations of 13 KIR genes and two CD94:NKG2 receptor genes and their distribution in the two haplotype groups in a panel of 233 unrelated healthy Greek Caucasians. We have typed genomic DNA for the presence of the putative KIR loci KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR3DL1, KIR3DL2, KIR3DL3, KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, and KIR3DS1 using modified polymerase chain reaction sequence-specific primers. The frequency of KIR loci combined with the linkage disequilibrium values suggest that the Greek population shares several general features with other Caucasoid populations studied before, but still distinguishes itself by the increased or decreased frequency of several alleles. The majority of the 45 different KIR genotypes seen in Greeks have been observed in Caucasoid populations studied before. Nevertheless, two of these genotypes, although met in other populations, have not been found in Caucasians before. One individual possesses a novel profile with no KIR inhibitory gene. The A haplotypes remain the most prevalent, with AA1 being the most common genotype, and the number of inhibitory KIRs being more variable than the number of noninhibitory KIRs in most haplotypes.

Heterotopic neo-osteogenesis from vascularized periosteum and bone grafts.

BACKGROUND: Periosteum is an osteogenic, flexible tissue. This study investigated the osteogenic potential of vascularized periosteal flaps in heterotopic conditions and compared it to the neo-osteogenesis from vascularized periosteal flaps combined with bone grafts with different properties (autologous and xenograft). METHODS: Vascularized periosteal flaps from the hindlimbs of 48 rabbits formed cylindrical pouches that were buried in muscles. The pouches were filled with autologous bone grafts (P/A group, n = 16), xenograft (P/X group, n = 16), or left empty (P/E group, n = 16). Specimens were harvested between 1 and 4 months and underwent radiographic, histologic, and histomorphometric evaluation. RESULTS: The total surface area was larger in the groups combined with bone grafts. Osseous apposition did not differ significantly in the P/A and P/X groups (p > 0.05). The central cavity contained hematopoietic cells (P/A), xenograft (P/X), or was absent (P/E). CONCLUSION: Vascularized periosteal flaps presented strong osteogenic capacity in heterotopic conditions. Combination with bone grafts resulted in larger specimens. The quality of neo-osteogenesis was not influenced by the different properties of combined bone grafts.