Left atrial size predicts outcome in severe but asymptomatic mitral regurgitation.

Patients with severe asymptomatic primary mitral regurgitation (MR) can be safely managed with an active surveillance strategy. Left atrial (LA) size is affected by MR severity, left ventricular function and is also associated with the risk of atrial fibrillation and may be an integrative parameter for risk stratification. The present study sought to determine the predictive value of LA size in a large series of asymptomatic patients with severe MR. 280 consecutive patients (88 female, median age 58 years) with severe primary MR and no guideline-based indications for surgery were included in a follow-up program until criteria for mitral surgery were reached. Event-free survival was determined and potential predictors of outcome were assessed. Survival free of any indication for surgery was 78% at 2 years, 52% at 6 years, 35% at 10 years and 19% at 15 years, respectively. Left atrial (LA) diameter was the strongest independent echocardiographic predictor of event-free survival with incremental predictive value for the thresholds of 50, 60 and 70 mm, respectively. In a multivariable analysis that encompassed age at baseline, previous history of atrial fibrillation, left ventricular end systolic diameter), LA diameter, sPAP > 50 mmHg and year of inclusion, LA diameter was the strongest independent echocardiographic predictor of event-free survival (adjusted HR = 1.039, p < 0.001). LA size is a simple and reproducible predictor of outcome in asymptomatic severe primary MR. In particular, it may help to identify patients who may benefit from early elective valve surgery in heart valve centers of excellence.

Surgical Transmitral Thrombectomy to Prevent Recurrent Stroke in Acute Myocardial Infarction.

Left ventricular (LV)-thrombi occur in up to 14 % of patients with acute myocardial infarction (AMI) in the era of primary percutaneous coronary intervention. For these patients, anticoagulant therapy (AC) is recommended by AMI-guidelines. When, despite AC, LV-thrombi lead to embolism, surgical thrombectomy is an option, which is not mentioned or not recommended in AMI-guidelines. We report a 46-year old female patient with AMI. An 80 % stenosis of the proximal left anterior descending coronary artery was treated by a drug-eluting stent. Thrombi within the akinetic LV-apex became mobile despite AC and dual antiplatelet therapy, and a cerebellar stroke occurred. By a transmitral surgical approach with endoscopic assistance the thrombi were completely removed. Postoperative course and 12-months follow-up were uneventful. LV-thrombi should be observed carefully regarding changes in morphology. Surgical thrombectomy of LV-thrombi is a rare treatment option to prevent imminent embolism. Benefits versus risks of surgical removal of LV-thrombi need to be carefully weighted.

Open Transcatheter Mitral Valve Implantation Into the Native Mitral Valve for Inoperable "Big MAC".

Because of the growing population of older adult patients, the prevalence of severe mitral annulus calcification ("big MAC") is increasing. The surgical techniques used to treat big MACs are technically demanding; despite the technical aspect, up to one-third of patients are considered too high risk for conventional surgery but are candidates for the coulisse technique, which is a procedure that implants a transcatheter valve into a native mitral annulus. The anterior leaflet is unfolded, thus reducing the risk of obstructing the left ventricular outflow tract and for paravalvular leak and avoiding valve migration. Preoperative planning, based on a computed tomography scan, is mandatory.

Unilateral acute lung injury in pig: a promising animal model.

BACKGROUND: Acute lung injury (ALI) occurs in 23% unilateral. Models of unilateral ALI were developed and used previously without clearly demonstrating the strictly unilateral nature and severity of lung injury by the key parameters characterizing ALI as defined by the American Thoracic Society (ATS). Thus, the use of unilateral ALI remained rare despite the innovative approach. Therefore, we developed a unilateral model of ALI and focused on the crucial parameters characterizing ALI. This model can serve for direct comparisons between the injured and intact lungs within single animals, thus, reducing the number of animals required for valid experimental conclusions. METHODS: We established the model in nine pigs, followed by an evaluation of key parameters in six pigs (main study). Pigs were ventilated using an adapted left double-lumen tube for lung separation and two ventilators. ALI was induced in the left lung with cyclic rinsing (NaCl 0.9% + Triton® X-100), after which pigs were ventilated for different time spans to test for the timing of ALI onset. Ventilatory and metabolic parameters were evaluated, and bronchoalveolar lavage (BAL) was performed for measurements of inflammatory mediators. Finally, histopathological specimens were collected and examined in respect of characteristics defining the lung injury score (LIS) as suggested by the ATS. RESULTS: After adjustments of the model (n = 9) we were able to induce strictly left unilateral ALI in all six pigs of the evaluation study. The median lung injury score was 0.72 (IQR 0.62-0.79) in the left lung vs 0.14 (IQR 0.14-0.16; p < 0.05) in the right lung, confirming unilateral ALI. A significant and sustained drop in pulmonary compliance (Cdyn) of the left lung occurred immediately, whereas Cdyn of the right lung remained unchanged (p < 0.05). BAL fluid concentrations of interleukin-6 and -8 were increased in both lungs. CONCLUSIONS: We established a model of unilateral ALI in pigs, confirmed by histopathology, and typical changes in respiratory mechanics and an inflammatory response. This thoroughly evaluated model could serve as a basis for future studies and for comparing pathophysiological and pharmacological changes in the uninjured and injured lung within the same animal.

Percutaneous mechanical circulatory support from the collaborative multicenter Mechanical Unusual Support in TAVI (MUST) Registry.

OBJECTIVES: To evaluate the use and outcomes of percutaneous mechanical circulatory support (pMCS) utilized during transcatheter aortic valve implantation (TAVI) from high-volume centers. METHODS AND RESULTS: Our international multicenter registry including 13 high-volume TAVI centers with 87 patients (76.5 ± 11.8 years, 63.2% men) who underwent TAVI for severe aortic stenosis and required pMCS (75.9% VA-ECMO, 19.5% Impella CP, 4.6% TandemHeart) during the procedure (prior to TAVI 39.1%, emergent rescue 50.6%, following TAVI 10.3%). The procedures were considered high-risk, with 50.6% having severe left ventricular dysfunction, 24.1% biventricular dysfunction, and 32.2% severe pulmonary hypertension. In-hospital and 1-year mortality were 27.5% and 49.4%, respectively. Patients with prophylactic hemodynamic support had lower periprocedural mortality compared to patients with rescue insertion of pMCS (log rank = 0.013) and patients who did not undergo cardiopulmonary resuscitation during the TAVI procedure had better short and long term survival (log rank <0.001 and 0.015, respectively). CONCLUSIONS: Given the overall survival rate and low frequency of pMCS-related complications, our study results support the use of pMCS prophylactically or during the course of TAVI (bailout) in order to improve clinical outcomes in high-risk procedures or in case of acute life-threatening hemodynamic collapse.

2020 update of the Austrian Society of Cardiology (ÖKG) and the Austrian Society of Cardiac Surgery (ÖGHTG) on the position statement of the ÖKG and ÖGHTG for transcatheter aortic valve implantation 2011.

This position statement is an update to the 2011 consensus statement of the Austrian Society of Cardiology (ÖKG) and the Austrian Society of Cardiac Surgery (ÖGTHG) for transfemoral transcatheter aortic valve implantation.Due to a number of recently published studies, broadening of indications and recommendations of medical societies and our own national developments, the ÖKG and the ÖGHTG wish to combine the 2017 ESC/EACTS guidelines for the management of valvular heart disease with a national position paper and to focus on certain details for the application in Austria. Thus, this position statement serves as a supplement and further interpretation of the international guidelines.

Early Antibiotic Prophylaxis Prior to Bypass Surgery Improves Tissue Penetration.

BACKGROUND: We previously identified preparation of the internal mammary artery as a risk factor significantly impairing antibiotic tissue penetration into the presternal subcutaneous tissue. We, therefore, adapted our dosing schema regarding preoperative timing to overcome this risk factor. METHODS: Eight patients who underwent coronary artery bypass grafting with a left internal mammary artery and vein grafts were included in this clinical trial. Cefazolin (4 g) was administered twice (3 hours and 1 hour) prior to skin incision and once during skin closure (2 g). Antibiotic concentrations were measured with subcutaneous microdialysis probes on both sternal sides. Results were directly compared with the previously published patient cohort receiving the standard schema (4 g cefazolin prior to skin incision and 2 g during closure). RESULTS: All patients (7 male, 1 female, 69 ± 7 years, 26.3 ± 3.9 kg/m2) survived the perioperative period. Mean area under the curve on the right and left sternal side was 117.0 ± 92.5 µg/mL and 114.5 ± 83.2 µg/mL, respectively (p = 0.95). This was well above the previously measured mean peak tissue concentrations without early preoperative antibiotic administration on the side of mammary artery harvesting (52.4 ± 48.5 µg/mL vs. 13.1 ± 5.8 µg/mL; p = 0.039). The %fT > minimal inhibitory concentration (MIC) for Staphylococcus epidermidis and Staphylococcus aureus during the first 10 hours in presternal tissue was ≥ 70% but did not differ compared with standard schema. CONCLUSIONS: Early, additional preoperative administration of cefazolin was able to significantly increase peak tissue concentrations during surgery compared with the standard protocol. No difference, however, could be achieved in the percentage of time during which the concentration exceeded the MIC.

Prognostic Value of Right Ventricular Dysfunction and Tricuspid Regurgitation in Patients with Severe Low-Flow Low-Gradient Aortic Stenosis.

Long and mid-term data in Low-Flow Low-Gradient Aortic Stenosis (LFLG-AS) are scarce. The present study sought to identify predictors of outcome in a sizeable cohort of patients with LFLG-AS. 76 consecutive patients with LFLG-AS (defined by a mean gradient <40 mmHg, an aortic valve area ≤1 cm2 and an ejection fraction ≤50%) were prospectively enrolled and followed at regular intervals. Events defined as aortic valve replacement (AVR) and death were assessed and overall survival was determined. 44 patients underwent AVR (10 transcatheter and 34 surgical) whilst intervention was not performed in 32 patients, including 9 patients that died during a median waiting time of 4 months. Survival was significantly better after AVR with survival rates of 91.8% (CI 71.1-97.9%), 83.0% (CI 60.7-93.3%) and 56.3% (CI 32.1-74.8%) at 1,2 and 5 years as compared to 84.3% (CI 66.2-93.1%), 52.9% (CI 33.7-69.0%) and 30.3% (CI 14.6-47.5%), respectively, for patients managed conservatively (p = 0.017). The presence of right ventricular dysfunction (HR 3.47 [1.70-7.09]) and significant tricuspid regurgitation (TR) (HR 2.23 [1.13-4.39]) independently predicted overall mortality while the presence of significant TR (HR 3.40[1.38-8.35]) and higher aortic jet velocity (HR 0.91[0.82-1.00]) were independent predictors of mortality and survival after AVR. AVR is associated with improved long-term survival in patients with LFLG-AS. Treatment delays are associated with excessive mortality, warranting urgent treatment in eligible patients. Right ventricular involvement characterized by the presence of TR and/or right ventricular dysfunction, identifies patients at high risk of mortality under both conservative management and after AVR.

Concomitant Transapical Transcatheter Aortic Valve Implantation and Transapical Mitral Valve Repair With NeoChord Implantation.

One-third of the patients with severe symptomatic aortic valve stenosis (sAS) present with hemodynamic relevant mitral valve insufficiency (rMI). In patients who undergo conventional surgery, the rMI never would be left untreated; however, in cases of transcatheter aortic valve implantation (TAVI), the impact of rMI is often overlooked and left untreated. The combination of transapical TAVI (TA-TAVI) and NeoChord implantation represents a novel, promising therapeutic option for high-risk-surgery patients with sAS and rMI due to a prolapsed or flailed leaflet. This case report describes 2 patients (1 male, 1 female; mean age 82 years) who underwent TA-TAVI and concomitant NeoChord implantation at our institute. Both presented with sAS and rMI due to a prolapse of the P2 segment of the mitral valve. At first, the TA-TAVI was implanted under angio-guidance, followed by three-dimensional echo-guided implantation of the NeoChords, through the same approach, which was slightly posterior and lateral to the apex. TA-TAVI using an Edwards Sapien 3 (26 mm, n = 1 and 29 mm, n = 1) and NeoChord implantation (2 in the first and 3 in the second patient) was successful in both cases. Post-intervention discharge echo indicated no paravalvular or central insufficiency after the procedure and only a trace of mitral valve insufficiency. TA-TAVI and concomitant NeoChord implantation is a feasible and promising treatment option for high-risk patients with rMI. Despite its technical demands, in experienced hands, it is a safe procedure for those not well suited for surgical intervention.

The "Paper Roll": A Simple but Useful Tool for Minimal Invasive Mitral Valve Repair Surgery.

During minimal invasive mitral valve repair, excessive valve tissue, as in myxomatous or Barlow disease, might be cumbersome to analyze and treat the subvalvular mitral valve apparatus. We developed a new, adaptive, flexible, and easy-to-use technique for better visualization of the subvalvular apparatus. After visualization of the mitral valve, a simple sterile paper ruler was curled up to a roll 1 cm in diameter and inserted through the mitral valve. By means of two endo forceps, the paper roll was uncurled to the desired diameter, thus pushing the valve leaflets away, allowing for a direct view onto the subvalvular apparatus. This technique was successfully used in 34 consecutive patients (mean ± SD age = 57.2 ± 11.5 years; 22 male). The calculated risk score for additive EuroScore, logistic EuroScore, and EuroScore II was 4 ± 2, 3.2 ± 2.1, and 2.5 ± 5.4, respectively. No patient died within the first 30 days. All patients presented mitral valve insufficiency grade 0 to 1 postoperatively. Artificial chords were implanted in all patients (3.6 ± 1.8 chords per patient). This simple, adaptive, and cheap technique facilitates the approach to the subvalvular apparatus, especially in patients with myxomatous or Barlow disease. The ease of use allows for prompt approach to the papillary muscles and quick removal.

Five-year haemodynamic outcomes of the first-generation SAPIEN balloon-expandable transcatheter heart valve.

AIMS: Transcatheter aortic valve implantation (TAVI) has gained rapid acceptance for patients with severe aortic stenosis (AS) at high surgical risk for conventional valve replacement. Although TAVI is now a relatively mature technique, limited data about long-term valvular function are available. Our aim was to report the five-year echocardiographic data evaluating valve performance from three early European feasibility studies designed to assess the safety and effectiveness of the first-generation balloon-expandable transcatheter heart valve (SAPIEN THV). METHODS AND RESULTS: A total of 410 patients were enrolled in the following single-arm, non-randomised, prospective multicentre clinical studies: REVIVE II, TRAVERCE and PARTNER EU. Five-year follow-up was completed in 114 surviving patients. Mean patient age was 82.3±5.6 years; 63.4% were female. The mean logistic EuroSCORE was 28.4±13.3%. NYHA Class III/IV was reported in 92.5%. At five years, the mean effective orifice area (EOA) was 1.6±0.6 cm² (n=34) and the mean gradient was 11.7±5.4 mmHg (n=39). In paired patient data, the difference between discharge and five-year EOA was 0.1±0.7 cm² (p=0.3956) and mean gradient was 2.2±5.7 mmHg (p=0.0900). At discharge and five years, respectively, aortic regurgitation (AR) was evaluated as none/trace in 66.6% (n=162/243) and 55.3% (n=19/38), mild in 28.4% (n=69/243) and 39.5% (n=15/38), and moderate in 4.9% (n=12/243) and 5.3% (n=2/38). No severe AR was reported at follow-up. Valve thrombosis was observed in three patients and occurred within one year. No valve-related explants and no case of structural valve deterioration have been reported. CONCLUSIONS: Long-term echocardiographic outcomes in high-risk patients with severe AS suggest stable haemodynamic function of first-generation balloon-expandable SAPIEN THVs at five years, with no worsening of AR severity over time.

Cefazolin and linezolid penetration into sternal cancellous bone during coronary artery bypass grafting.

OBJECTIVES: Deep sternal wound infection is a severe complication after cardiac surgery. Insufficient antibiotic target site concentrations may account for variable success of perioperative prophylaxis. Therefore, we measured perioperative penetration of cefazolin and of linezolid into sternal cancellous bone after sternotomy in coronary artery bypass grafting (CABG) patients by in vivo microdialysis. METHODS: Nine patients underwent CABG using a skeletonized left internal mammary artery. Standard antibiotic prophylaxis consisted of 4 g cefazolin prior to skin incision and additional 2 g during skin closure. In addition, 600 mg of linezolid were administered prior to skin incision and after 12 h for study purposes. Two microdialysis probes were inserted into the sternal cancellous bone (left and right side) after sternotomy. RESULTS: First mean peak cefazolin and linezolid plasma concentrations were 273 ± 92 µg/ml and 22.1 ± 8.9 µg/ml, respectively. Mean peak concentrations of antibiotics in sternal cancellous bone on the left and right sternal side were 112 ± 59 µg/ml and 159 ± 118 µg/ml for cefazolin and 10.9 ± 4.0 µg/ml and 12.6 ± 6.1 µg/ml for linezolid, respectively. Cefazolin exceeded the required tissue concentrations for relevant pathogens by far, but linezolid did not gain effective tissue concentrations in all patients for some relevant pathogens. Mammary artery harvesting had no significant effect on antibiotic tissue penetration. CONCLUSIONS: Direct measurement of antibiotic concentration in sternal cancellous bone with in vivo microdialysis is technically demanding but safe and feasible. We could demonstrate sufficient antibiotic coverage with our standard cefazolin-dosing regimen in the sternal cancellous bone during cardiac surgery. Mammary artery harvesting had no clinically relevant effect on tissue penetration. Linezolid concentrations were not sufficient for some relevant pathogens.

Acute hyponatremia after cardioplegia by histidine-tryptophane-ketoglutarate--a retrospective study.

BACKGROUND: Hyponatremia is the most common electrolyte disorder in hospitalized patients and is known to be associated with increased mortality. The administration of antegrade single-shot, up to two liters, histidine-tryptophane-ketoglutarate (HTK) solution for adequate electromechanical cardiac arrest and myocardial preservation during minimally invasive aortic valve replacement (MIAVR) is a standard procedure. We aimed to determine the impact of HTK infusion on electrolyte and acid-base balance. METHODS: In this retrospective analysis we reviewed data on patient characteristics, type of surgery, arterial blood gas analysis during surgery and intra-/postoperative laboratory results of patients receiving surgery for MIAVR at a large tertiary care university hospital. RESULTS: A total of 25 patients were included in the study. All patients were normonatremic at start of surgery. All patients developed hyponatremia after administration of HTK solution with a significant drop of serum sodium of 15 mmol/L (p < 0.01). Measured osmolality did not change during all times of surgery compared to start of surgery (p = 0.28 - p = 0.79), indicating isotonic hyponatremia. After administration of HTK solution pH fell significantly due to development of metabolic acidosis. CONCLUSIONS: Acute hyponatremia during cardioplegia with HTK solution is isotonic and should probably not be corrected without presence of hypotonicity as confirmed by measurement of serum osmolality.

Aortic dissection type A after right atrial cryoablation during port access mitral valve surgery.

The case of a 63-year-old woman who underwent minimal invasive mitral and tricuspid valve repair and a concomitant CryoMaze is described. During creation of the last lesion of the right-sided maze procedure, dissection of the ascending aorta occurred that necessitated emergency sternotomy, replacement of the ascending aorta, and aortocoronary bypass grafting to the right coronary artery (RCA) because of detachment of the RCA from the aortic annulus. Repair of this complication was successful; nevertheless, the patient died 5 days after the operation because of multiorgan failure. The cause of this complication can only be speculated, but a relation to the CyroMaze is obvious. Because of the restricted incision with impaired vision especially in the area of the right atrial appendage, the cryoprobe could have come into contact with the orifice of the RCA during the last lesion, with subsequent detachment of the RCA from the aorta, which could subsequently have caused dissection.

The third hand--a simple but useful tool for holding the sheath during transapical transcatheter aortic valve implantation.

Transapical aortic valve implantation is an evolving technology for treating high-risk patients with symptomatic aortic stenosis. The transition to a catheter based implantation technique inherits one fundamental change: the native valve stays in place and is no longer removed. The selection of the correct plane of the aortic annulus, therefore, is mandatory. In addition, exact alignment of the sheath and catheters according to axis of the ascending aorta is imperative for correct implantation. That is why any additional movements have to be avoided. To aid in better workflow, we developed an easy-to-use cheap holder for the introduction sheath. By using a rigid table mount instrument holder the sheath can easily be fixed in the desired orientation, abolishing any movement and reducing the X-ray load to the implanting surgeon.

Prolonged venoarterial extracorporeal membrane oxygenation after transplantation restores functional integrity of severely injured lung allografts and prevents the development of pulmonary graft failure in a pig model.

OBJECTIVE: Prolonged venoarterial extracorporeal membrane oxygenation support during transplantation provides reduction of pulmonary artery flow and allows for protective ventilation. This approach might have the potential to restore function of lungs that would be unsuitable for transplantation. METHODS: Left lung transplantation was performed on 16 pigs. Lungs from brain-dead animals were stored for 22 hours at 4 degrees C. Recipients in group A (n = 8) underwent transplantation without cardiopulmonary support followed by ventilation with 10 mL/kg body weight tidal volume. Animals in group B (n = 8) underwent transplantation during venoarterial extracorporeal membrane oxygenation, which was continued for 22 hours, and received low-tidal-volume (5 mL/kg body weight) ventilation. One hour after transplantation, the right lung was excluded. Graft function was compared immediately after exclusion of the contralateral lung (time point 1), 1 hour later (time point 2), and 1 hour after discontinuation of extracorporeal membrane oxygenation (time point 3). RESULTS: Four animals in group A did not reach time point 2; all died of pulmonary edema. All animals in group B survived, and at time point 3, the mean Pao(2) value was 323 +/- 129 mm Hg. At time point 2, oxygenation and lung compliance were higher in group B than in group A, whereas pulmonary artery pressure was lower. The same was true when comparing results of group B at time point 3 with results of group A at time point 2. CONCLUSIONS: Transplantation during extracorporeal membrane oxygenation with continued use for 24 hours restores function of damaged donor lungs. This could expand the donor pool through wider use of marginal donors.

Extended videoscopic robotic thymectomy with the da Vinci telemanipulator for the treatment of myasthenia gravis: the Vienna experience.

Surgical treatment of myasthenia gravis should include the complete resection of the thymus with the whole fatty tissue adherent to the pericardium for immunologic as well as oncologic reasons. The aim of the current study was to investigate the efficacy and safety of robotic approach. A total of 18 patients with myasthenia gravis (mean age 44 years) have been operated robotically via a left-sided approach. Preoperative MGFA (Myasthenia Gravis Foundation of America) classification was: Class I n=4, Class IIa n=4, Class IIb n=5, and Class IIIa n=3, IIIb n=2. Total endoscopic resection was feasible in 17/18 patients. One patient had to be converted due to bleeding. In the remaining patients, operative time was 175 min, intensive care unit (ICU) one day, hospital stay four days. In all patients it was possible to perform an extended thymic resection. MGFA post-intervention status after a mean of 18 months follow-up showed complete stable remission n=5, pharmacologic remission n=4, minimal manifestations n=5, unchanged n=1. Complete endoscopic thymus surgery with the da Vinci surgical system enables a complete and extended resection of all thymic tissue in the mediastinum. Due to the minimal trauma, patients can return to full activity within a short time.

Management of open chest and delayed sternal closure with the vacuum assisted closure system: preliminary experience.

The management of open chest with the vacuum assisted closure (VAC) system was evaluated in terms of impact on cardiac hemodynamics, respiratory parameters, complications, incidence of wound infection, overall handling and outcome in 22 patients during 2005 and 2008 after cardiac surgery. The decision to leave the sternum open was made electively in all patients at the time of primary operation or reexploration. In four patients the VAC was implanted during the primary operation. In the remainder the VAC was implanted after a mean of five days after the primary operation. The overall mortality rate was 45% (10/22). None of the patients developed a sternal wound infection, nor were there any VAC related complications. Management of open chest with the VAC system can be considered as an alternative to sterile draping. The VAC has no negative impact on cardiac hemodynamics as well as respiratory mechanics. The feared complication of right ventricular rupture and massive bleeding can be effectively prevented. Through the stabilizing of the thoracic cage, the patient can be easily moved and mobilized for nursing reasons and pneumonia prevention. Furthermore, the VAC effectively prevents the contamination of the wound and the mediastinum with potential subsequent infection.

The impact of perioperative atelectasis on antibiotic penetration into lung tissue: an in vivo microdialysis study.

OBJECTIVE: Postoperative pneumonia is a potentially devastating complication associated with high mortality in intensive care unit (ICU)-patients. One of the major predisposing factors is the perioperative occurrence of atelectatic formations in non-dependent lung areas. Perioperative ventilation/perfusion mismatch due to atelectasis may influence antibiotic distribution to lung tissue, hence increasing the risk of postoperative pneumonia. We evaluated whether differences in ventilation/perfusion mismatch can influence antibiotic distribution into lung tissue by means of in vivo microdialysis, comparing patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) (atelectasis model), with patients operated with the off-pump coronary artery bypass grafting (OPCAB)-technique. PATIENTS AND METHODS: We compared five patients operated with CPB (CPB-group) and five patients undergoing CABG with OPCAB-technique (OPCAB-group). Levofloxacin (500 mg) was administered intravenously, after surgery, in the ICU. Time versus concentration profiles of levofloxacin in lung tissue and plasma were measured at regular time-intervals. RESULTS: In the OPCAB-group, the median of the maximum concentration of levofloxacin in lung tissue (4.1 microg ml(-1) +/- 7, range 3.7-11.8 microg ml(-1)) was significantly higher compared with the CPB-group (2.5 microg ml(-1) +/- 0.3, range 2.0-2.9 microg ml(-1)) (P = 0.046). Median levofloxacin tissue/plasma area under the concentration curve (AUC) ratio in lung tissue was 0.3 +/- 0.2 (range 0.1-0.7) in the CPB-group versus 0.7 +/- 1.6 (range 0.4-0.8) in the OPCAB-group (P = 0.015). CONCLUSIONS: Data indicate that postoperative interstitial antibiotic concentration is influenced by perioperative atelectasis formation. Our findings suggest the re-evaluation of clinical dosing schemas of antibiotic therapy in a variety of diseases associated with atelectasis formation.