Diagnosis and treatment of Bartonella endocarditis

The Bartonella genus comprises more than 20 species of Gram-negative rods which are difficult to culture. These are facultative intracellular bacteria. Humans are reservoir hosts for B. quintana and B. bacilliformis or accidental hosts for other species. Bartonella is a cause of zoonosis. Bartonella infection can be completely asymptomatic or can be linked to various conditions. Our experience with Bartonella endocarditis from 2012-2017 is presented. The most effective diagnostic method for Bartonella endocarditis is PCR detection of DNA of the pathogen from excised valve tissue. The European Society of Cardiology (ESC) in the guidelines from 2015 recommends the combination doxycycline gentamycin for the treatment of Bartonella endocarditis.

Tissue and plasma concentrations of cephuroxime during cardiac surgery in cardiopulmonary bypass — a microdialysis study

Aim: Wound and mediastinal infections are still very serious complications of open-heart surgery, in spite of the use of prophylactic antibiotics. The use of cardiopulmonary bypass (CPB) is associated with profound physiological changes affecting the pharmacokinetic behaviour of antibiotics.

The aim of this pilot study was to monitor the tissue concentrations of cephuroxime (prophylactic antibiotic) in skeletal muscle during cardiac surgery using CPB by interstitial microdialysis. These concentrations were compared with plasma concentrations of cephuroxime.

Material and methods: Nine adult patients operated on using CPB were enrolled in this study. Cephuroxime was used as a prophylactic antibiotic (1st dose — 3 g of cefuroxime i.v. with anesthesia induction, 2nd dose — 1.5 g i.v. after CPB with protamine sulphate, 3rd dose — 1.5 g i.v. 8 hours after the surgery).

Interstitial microdialysis was performed by probe CMA 60 (CMA Microdialysis AB, Sweden) inserted into the patient's deltoid muscle. Concentrations of cephuroxime in dialysates and in plasma were determined by the modified fluid chromatography method. The unbound cephuroxime fraction in plasma was obtained by using an ultrafiltration method. Samples of dialysates were collected at the following intervals: before CPB, each 30 minutes of CPB, at the end of CPB. Samples of blood were collected at these intervals: incision, start of CPB, each 30 minutes of CPB, at the end of CPB, at the end of surgery. Concentrations of cephuroxime in tissue were corrected by in vivo recoveries of the microdialysis probes.

Results: Plasma concentrations of cephuroxime were 163.5 ± 40.1, 79.3 ± 17.4, 73.7 ± 16.8, 66.1 ± 18.3, 57.0 ± 10.9, 120.7 ± 29.9 (mg . L—1) and concentrations of free plasma fraction of cephuroxime were 119.5 ± 35.2, 67.8 ± 15.5, 66.0 ± 12.5, 54.8 ± 12.2, 49.6 ± 9.8, 102.6 ± 26.0 (mg . L—1).

The concentrations of cephuroxime in dialysates were 44.3 ± 15.7, 36.1 ± 11.6, 31.9 ± 9.3, 34.6 ± 12.3, 27.6 ± 12.9, 56.7 ± 17.6 (mg . L—1).

The mean in vivo recovery of cephuroxime in this study was 30%.

Corrected concentrations (calculated by in vivo recovery) of cephuroxime in skeletal muscle were 148, 120, 106, 115, 92, 189 (mg . L—1).

Conclusion: Our preliminary results show that CPB can modify the time course of cephuroxime plasma and tissue concentrations. A decrease in plasma drug concentrations occurred at the start of CPB and lasted until CPB ended. An increase in plasma concentrations corresponds to the second drug dose after CPB. The concentrations of cephuroxime in skeletal muscle (corrected by recovery) during CPB are higher than plasma concentrations. It is influenced by important changes during CPB; closely associated with hemodilution, a shift of intravascular volume, solutes and albumin to the extravascular space and inconstant protein binding of cephuroxime during operation. Perfusion (2007) 22, 129—136.

[Minimally invasive video-assisted operations for heart disease]

INTRODUCTION

Minimally invasive surgical access for the treatment of mitral and tricuspid valves has become an alternative method to the conventional approach via median sternotomy. The aim of this paper is to evaluate our experience and results with minimally invasive approach in cardiac surgery at our institution.

MATERIAL AND METHODS

A total of 52 patients underwent minimally invasive cardiac surgery between November 2011 and March 2013. Right lateral minithoracotomy and femoral vessels cannulation for cardiopulmonary bypass was used. Follow-up data was collected in a prospective database and analysed retrospectively.

RESULTS

The mean age of patients was 60.9 ± 11.6 years (female patients accounted for 63.5%). The procedures performed included mitral valve repair in 44 (85%) patients and tricuspid valve repair in 25 (48%). Atrial septal defect closure was performed in 8 (15%) patients and cryoablation of atrial fibrillation in 26 (50%) patients. There were 75% combined procedures. The median duration of the operation was 235 (155-315) minutes. The median length of cardiopulmonary bypass and crossclamp time was 139 (89-225) and 92 (51-168) minutes, respectively. The median duration of postoperative hospital stay was 12.5 (6-34) days. Hospital and 30-day mortality was 0%. At follow-up (121.3 ± 32.72 days), two patients (3.8%) required reoperation (1 for right haemothorax, 1 for aortic valve insufficiency).

CONCLUSION

Minimally invasive access has been adopted as a routine method for the therapy of valve disease. The minithoracotomy approach is a safe and feasible technique with comparable mortality and in-hospital morbidity.

Impact of cardiopulmonary bypass on peripheral tissue metabolism and microvascular blood flow

The aim of this study was to monitor and compare the changes in metabolism and blood flow in the skeletal muscles during cardiac operations performed with cardiopulmonary bypass (CPB) and operations without CPB (off-pump) by means of interstitial microdialysis (Figure 1). Surgical revascularization, coronary artery bypass grafting (CABG), was performed in 40 patients randomized to two groups. Twenty patients (On-Pump Group) were operated on using CPB, 20 patients (Off-Pump Group) were operated on without CPB. Interstitial microdialysis was performed by 2 probes of a CMA 60 (CMA Microdialysis AB, Solna, Sweden) inserted into the patient's deltoid muscle. Microdialysis measurements were performed at 30-minute intervals. Glucose, lactate, pyruvate and glycerol as markers of basic metabolism and tissue perfusion were measured in samples from the first probe, using a CMA 600 Analyzer (CMA Microdialysis AB). Blood flow through the interstitium was monitored by means of dynamic microdialysis of ethanol as a flow-marker in the dialysates taken from the second probe (ethanol dilution technique). Results in both the groups were statistically processed and compared. Both the groups were similar in respect of preoperative characteristics. Dynamic changes of interstitial concentrations of the measured analytes were found in both the patient groups (on-pump vs. off-pump) during the operation. There was no significant difference in dialysate concentrations of glucose and lactate between the groups. Significant differences were detected in pyruvate and glycerol interstitial concentrations, lactate/pyruvate ratio and lactate/glucose ratio between the on-pump vs. off-pump patients. In the Off-Pump Group, pyruvate concentrations were higher and the values of concentrations of glycerol lower. The lactate/pyruvate ratio and the lactate/glucose ratio, indicating the aerobic and anaerobic tissue metabolism status, were lower in the Off-Pump Group. There was no significant difference in dialysate concentrations of ethanol as a flow-marker during the surgery in either of the groups. There was no statistically significant difference between the groups (On-Pump Group vs. Off-Pump Group) comparing the postoperative clinical outcome (ICU stay, ventilation duration, length of hospital stay). The dynamic changes in the interstitial concentrations of the glucose, glycerol, pyruvate and lactate were found in both the groups of patients (On-Pump Group and Off-Pump Group), but there was no difference in local blood flow when the ethanol dilution technique was used. These results showed significantly higher aerobic metabolic activity of the peripheral tissue of patients in the Off-Pump Group vs. the On-Pump Group during the course of cardiac revascularization surgery. Results suggest that extracorporeal circulation, cardiopulmonary bypass, compromises peripheral tissue (skeletal muscles) energy metabolism. These changes have no impact on the postoperative clinical outcome; no significant difference between the groups was found.

Transitions in the orientational order of liquid crystals induced by periodic patterned substrates

The orientational order of liquid crystals (LCs) induced by periodic patterned substrates has been investigated with cells coated by azopolymer films that could be photoaligned in a controlled way. Two regimes were observed depending on the period of the patterns: (i) above 3.0 microm the LC follows the direction imposed by the patterned substrate since the energy stored in the surface potential minimizes the elastic energy of the LC medium. (ii) For periods smaller than 1.0 microm a homogeneous in-plane state was induced and the LC did not follow the orientation imposed by the surface. This in-plane transition could be explained qualitatively by a theoretical model based on the competition between the Frank-Oseen elastic energy and the phenomenological surface potential. The results also suggest an out-of-plane transition for the LC director as the period was reduced. These results agree with data in the literature for patterned substrates with completely distinct architectures. This indicates that for a particular LC sample the overall behavior depends basically on the texture period instead of the texture architecture. The textures were characterized with a scanning near-field optical microscope (SNOM), which allowed simultaneous morphological and optical images in the submicrometer range.

[Interstitial microdialysis in the clinical and experimental medicine]

Interstitial microdialysis is a minimally invasive method that allows biochemical monitoring of endogenous and exogenous substances in extracellular tissue space. The method is based on sampling of soluble molecules from the interstitial space fluid by means of a semipermeable membrane. Microdialysis has been applied in primary and clinical research of metabolic changes and the blood flow in tissue interstitium and pharmacokinetic drug studies. Results obtained by microdialysis are gradually finding their place in clinical practice as well. This paper is aimed at presenting to the reader new technique of monitoring interstitial metabolism, its advantages, drawbacks and relevance for medicine.