Rotational thromboelastometry and conventional coagulation tests in patients undergoing major cardiac or aortic surgery: a retrospective single-center cohort study.

Algorithms for treatment of diffuse bleeding in cardiac surgery are based on intervention thresholds of coagulation tests, such as rotational thromboelastometry (ROTEM) or conventional laboratory tests. The relationship between these two approaches is unclear in patients with increased risk of coagulation abnormalities. We retrospectively analyzed the data of 248 patients undergoing major cardiac and/or aortic surgery. ROTEM and conventional laboratory tests were performed simultaneously after termination of cardiopulmonary bypass and protamine administration to investigate the extrinsic and intrinsic system, and to determine deficiencies in platelets and fibrinogen. We evaluated the association between ROTEM and conventional tests by linear regression analysis and compared the frequency of exceeding established thresholds for clinical intervention. Significant linear associations between ROTEM 10 min after the start of coagulation, and plasma fibrinogen concentration or platelet count (FIBTEM A10, R2 = 0.67, p < 0.001; EXTEM A10, R2 = 0.47, p < 0.001) were obtained. However, the 95% prediction intervals exceeded clinically useful ranges (92-233 mg/dL fibrinogen at the intervention threshold of FIBTEM A10 = 10 mm; 14 × 103-122 × 103/µL platelets at the intervention threshold of EXTEM A10 = 40 mm). The association between EXTEM and INR (R2 = 0.23), and INTEM and aPTT (R2 = 0.095) was poor. The frequency of exceeding intervention thresholds and, consequently, of triggering treatment, varied markedly between ROTEM and conventional tests (p < 0.001 for all comparisons). The predictability of conventional coagulation test results by ROTEM is limited, thus hampering the interchangeability of methods in clinical practice.

Perioperative Changes of Right Ventricular Function in Cardiac Surgical Patients Assessed by Myocardial Deformation Analysis and 3-Dimensional Echocardiography.

OBJECTIVES: To test the hypothesis that longitudinal strain of the right ventricle (RV) is significantly reduced in patients undergoing cardiac surgery with extracorporeal circulation and cardioplegic cardiac arrest at the end of surgery, whereas RV ejection fraction remains unchanged. DESIGN: Prospective observational cohort study. SETTING: Single university hospital. PARTICIPANTS: Thirty patients with normal myocardial function undergoing coronary artery bypass grafting with cardioplegic cardiac arrest. INTERVENTIONS: Right ventricular 3-dimensional echocardiography and strain analysis were performed preoperatively, intraoperatively, and postoperatively. MEASUREMENTS AND MAIN RESULTS: Peak longitudinal systolic strain of the RV lateral and inferior wall, RV outflow tract, and interventricular septum was reduced significantly at the end of surgery after sternal closure compared to preoperatively (lateral: -16 ± 5 v -22 ± 4, p < 0.001; inferior: -12 ± 4 v -19 ± 5, p < 0.001; outflow tract, -11 ± 5 v . -20 ± 6, p < 0.001; septum: -9 ± 3 v -14 ± 4, p < 0.001), whereas peak circumferential systolic strain of the RV lateral wall had increased significantly (-16 ± 4 v -12 ± 5, p = 0.008). Right ventricular ejection fraction remained stable (51 ± 6% v. 50 ± 7%, p = 0.34). CONCLUSION: In patients undergoing coronary artery bypass grafting with cardioplegic cardiac arrest, the longitudinal contraction of the RV lateral and inferior wall, the RV outflow tract, and the interventricular septum is impaired at the end of surgery. This impairment is compensated by an increase in circumferential contraction without changes in RV ejection fraction.

Important reduction of the radiation dose for pulmonary vein isolation using a multimodal approach.

Aims: The number of pulmonary vein isolation (PVI) ablation procedures is steadily increasing worldwide resulting in a substantial radiation exposure to patients and operators. The aim of our study was to reduce radiation exposure during these procedures to a critical amount without compromising patient safety. Methods and results: First, we assessed radiation exposure for primary PVI procedures over time (2005-2015) at the University Heart Center Freiburg-Bad Krozingen. Second, we prospectively evaluated in 52 patients, the efficacy and safety of a novel radiation reduction program (particularly applying an enhanced fluoroscopy pulse dose-reduction and optimized 3D-mapping system use). In 2035 primary PVI procedures, radiation exposure, assessed as estimated effective dose (eED in mSv, dose area product * 0.002 * conversion factor for females), fluoroscopy-time, and procedure-time decreased significantly from 2005 to 2015 (e.g. eED decreased from 9.3 (interquartile range (IQR) 6.4-13.4) mSv to 0.9 (IQR 0.5-1.6) mSv, p for trend <0.001). Importantly, application of the enhanced radiation reduction program further reduced eED to 0.4 mSv (IQR 0.3-0.6, P < 0.001 vs. control), a value not significantly different from slow-pathway ablation procedures (P = 0.41). Multiple linear regression analysis identified the radiation reduction program as the only independent variable associated with a decrease in radiation exposure. Conclusion: Radiation exposure during PVI decreased over the last decade and can further be reduced significantly by the implementation of an enhanced radiation reduction program.

Mechanisms of pulmonary vein reconnection after radiofrequency ablation of atrial fibrillation: the deterministic role of contact force and interlesion distance.

INTRODUCTION: Pulmonary vein reconnection (PVR) is an important cause of AF recurrence after ablation. With the advent of force sensing catheters, catheter-tissue contact can be determined quantitatively. Since contact force (CF) plays a major role in determining the characteristics of RF lesion, we prospectively assessed the mechanisms of PVR with regard to catheter-contact and lesion distances in patients undergoing AF ablation. METHODS AND RESULTS: Forty symptomatic AF patients underwent wide circumferential PV isolation (PVI) with SmartTouch™ CF catheter. The exact locations of acute PVI and spontaneous or adenosine-provoked PVR were annotated on CARTO. One thousand nine hundred and twenty-six RF lesions isolated 153 PVs. PVR occurred in 35 (23%) PVs: 22 (63%) adenosine-provoked and 13 (37%) spontaneous. CF was significantly lower at PVR versus PVI sites for RF lesions within 6 mm from these sites: mean CF 5 versus 11 g (P < 0.0001) and force-time integral (FTI) 225 versus 415 gs (P < 0.0001); 86% of PVR occurred with a mean CF < 10 g (FTI < 400 gs); and the remaining 14% occurred at ablation sites with a long interlesion distance (≥5 mm) despite mean CF ≥ 10 g. Eighty percent of PVR sites were located anteriorly. There were no significant differences in regard to arrhythmia freedom between the patients without (69%) versus with PVR (67%; P = 1.0). CONCLUSIONS: Acutely durable PVI can be achieved when RF lesions are delivered with a mean CF ≥ 10 g and an interlesion distance <5 mm. The majority of PVR occur anteriorly due to inadequate CF or long interlesion distances.

Enhanced efficiency of a novel porous tip irrigated RF ablation catheter for pulmonary vein isolation.

INTRODUCTION: Irrigated tip radiofrequency (RF) catheter ablation is the most frequently used technology for pulmonary vein isolation (PVI). The purpose of this study was to compare the efficiency and the safety of 2 different open irrigated tip RF ablation catheters. METHODS AND RESULTS: A total of 160 patients with symptomatic AF (29% persistent, 68% male, 61 ± 10 years) were randomized to circumferential PVI using 2 different irrigated tip catheters: (1) the novel Thermocool SF(®) with a porous tip (56 holes) or (2) the Thermocool(®) catheter with 6 irrigation holes at the distal tip in both power- and temperature-controlled modes. PVI procedural time and RF duration were significantly shorter with SF(®) versus Thermocool(®) catheter: 104.5 versus 114 minutes (P = 0.023) and 35.4 minutes versus 39.9 minutes (P < 0.001), respectively. Similarly, the total fluoroscopy time and dose were shorter with SF(®) versus. Thermocool(®) catheter: 21 minutes versus 24 minutes (P = 0.02) and 1014.5 µGy*m(2) versus 1377 µGy*m(2) (P < 0.0001), respectively. Irrigation volume was lower with SF(®): 600 mL versus 1100 mL, (P < 0.0001) and the rates of complications were not significantly different (0.6% vs 0.49%, P = 0.66). At 20.5 ± 7.5 months follow-up, there were no significant differences with regard to arrhythmia freedom between SF(®) (59.2%) and TC® groups (59.3%), (P = 0.61). CONCLUSIONS: Using the novel irrigated tip SF catheter, PVI is achieved within a shorter ablation and procedural durations. The underlying mechanisms and potential differences in RF lesion size remain to be elucidated.

Increased electrical nerve stimulation threshold of the sciatic nerve in patients with diabetic foot gangrene: a prospective parallel cohort study.

CONTEXT: Peripheral neuropathy may affect nerve conduction in patients with diabetes mellitus. OBJECTIVE: This study was designed to test the hypothesis that the electrical stimulation threshold for a motor response of the sciatic nerve is increased in patients suffering from diabetic foot gangrene compared to non-diabetic patients. DESIGN: Prospective non-randomised trial with two parallel groups. SETTING: Two university-affiliated hospitals. PARTICIPANTS: Patients scheduled for surgical treatment of diabetic foot gangrene (n = 30) and non-diabetic patients (n = 30) displaying no risk factors for neuropathy undergoing orthopaedic foot or ankle surgery. MAIN OUTCOME MEASURE: The minimum current intensity required to elicit a typical motor response (dorsiflexion or eversion of the foot) at a pulse width of 0.1 ms and a stimulation frequency of 1 Hz when the needle tip was positioned under ultrasound control directly adjacent to the peroneal component of the sciatic nerve. RESULTS: The non-diabetic patients were younger [64 (SD 12) vs. 74 (SD 7) years] and predominantly female (23 vs. 8). The geometric mean of the motor stimulation threshold was 0.26 [95% confidence interval (95% CI) 0.24 to 0.28] mA in non-diabetic and 1.9 (95% CI 1.6 to 2.2) mA in diabetic patients. The geometric mean of the electrical stimulation threshold was significantly (P < 0.001) increased by a factor of 7.2 (95% CI 6.1 to 8.4) in diabetic compared to non-diabetic patients. CONCLUSION: The electrical stimulation threshold for a motor response of the sciatic nerve is increased by a factor of 7.2 in patients with diabetic foot gangrene, which might hamper nerve identification.

Pulmonary artery vs. transpulmonary thermodilution for the assessment of cardiac output in mitral regurgitation: a prospective observational study.

CONTEXT: With increasing prevalence of mitral regurgitation, even noncardiac anaesthesiologists will be confronted by this disorder and will need to be familiar with the extended haemodynamic monitoring required. The assessment of cardiac output (CO) measured by transpulmonary thermodilution (COTP) has become an accepted alternative to the CO measured by thermodilution via pulmonary artery catheter (COPAC). However, the integrity of COTP in severe mitral regurgitation requires systematic evaluation. OBJECTIVE: This study was designed to test the hypothesis that transpulmonary thermodilution is compromised by severe mitral regurgitation. DESIGN: Prospective method comparison study. SETTING: Single university-affiliated hospital. PARTICIPANTS: Thirty patients with mitral regurgitation undergoing elective mitral valve repair. MAIN OUTCOME MEASURE: COTP and COPAC were determined in triplicate after induction of anaesthesia, and at the end of surgery after closure of the chest. The methods were compared using bias and precision statistics. RESULTS: Echocardiography revealed severe mitral regurgitation in most patients (n  =  27) after induction of anaesthesia. The least significant change in COTP (the minimum change in COTP required to detect a real change with a probability of 95%) was increased under the condition of mitral regurgitation (15.4  ±  10.2% after anaesthesia induction vs. 9.3  ±  5.9% after valve repair, P = 0.008), whereas it remained constant in COPAC (9.6  ±  5.4 vs. 8.5  ±  7.2%, P = 0.55). There was no significant bias between COTP and COPAC after anaesthesia induction [mean CO, 4.03 ±â€Š0.92 l  min; bias 0.12 l  min (95% confidence interval, CI, -0.073 to 0.311)], and after valve repair [mean CO 7.47  ±â€Š 1.44 l  min; bias 0.045 l  min (95% CI, -0.147 to 0.237)]. The percentage error was 28.4 and 13.6%, respectively. CONCLUSION: The results suggest that even severe mitral regurgitation has no significant impact on the accuracy of COTP. The precision of COTP was reduced under the condition of mitral regurgitation.

Results of open thoracoabdominal aortic replacement in patients unsuitable for or after endovascular repair with remaining disease components.

OBJECTIVES: Our goal was to evaluate outcomes in all-comer patients undergoing open thoracoabdominal aortic replacement either unsuitable for or after failed endovascular aortic repair. METHODS: Within a 4-year period, we analysed a consecutive series of 80 patients undergoing elective, urgent and emergency thoracoabdominal aortic replacement. Preoperative data, intraoperative data and outcomes were evaluated. Specific attention was given to technical refinements needed in patients after previous endovascular aortic repair. RESULTS: Eighty patients underwent thoracoabdominal aortic replacement: 11.3% (n = 9) had connective tissue disorders. Twenty-six patients (32.5%) had previous endovascular aortic repair and 54 (67.5%) did not have previous endovascular repair. The mean age was 64.2 ± 12 years, and 70% (n = 56) were male. The mean EuroSCORE was 7.9 ± 2.6. Urgent or emergency operations were done in 22.5% (n = 18). Overall mortality was 20% (n = 16); symptomatic spinal cord injury occurred in 5% (n = 4). We did not observe differences in survival according to the presence or absence of previous endovascular aortic repair (P = 0.524). Multivariate regression analysis revealed the amount of packed red blood cell units (P = 0.009, confidence interval 1.028-1.215, odds ratio = 1.117) as a predictor of in-hospital death. Follow-up was 100% (37.9 ± 15.8 months); freedom from aortic-related reintervention was 96.3%. CONCLUSIONS: Despite an early attrition rate, survival after open thoracoabdominal aortic replacement is excellent, and freedom from aortic-related reintervention is high. Open surgery continues to remain an essential component in the treatment armamentarium of acute and chronic thoracoabdominal aortic pathology.

Electrocardiographic diagnosis of atrial cardiomyopathy to predict atrial contractile dysfunction, thrombogenesis and adverse cardiovascular outcomes.

Thromboembolism and stroke are dreaded complications in atrial fibrillation (AF). Established risk stratification models identify susceptible patients, but their discriminative properties are poor. Atrial cardiomyopathy (ACM) is associated to thromboembolism and stroke in smaller studies, but the modalities used for ACM-diagnosis (MRI and endocardial mapping) are unsuitable for widespread population screening. We aimed to investigate an ECG-based diagnosis of ACM using amplified p-wave analysis (APWA) for stratification of thromboembolic risk and cardiovascular outcome. In this case-control study, ACM-staging was performed using APWA on digital 12-lead sinus rhythm-ECGs in patients with LAA-thrombus and a propensity-score-matched control-cohort. Left atrial contractile function and thrombi were evaluated by transesophageal echocardiography (TEE). Outcome for MACCE including death was assessed using official registries and structured phone interviews. Left-atrial appendage [LAA]-thrombi and appropriate sinus rhythm-ECGs for ACM-staging were found in 109 of 4086 patients that were matched 1:1 to control patients without thrombus (218 patients in total). Both cohorts were comparable regarding cardiovascular risk factors, anticoagulants and CHA2DS2-VASC-score. ACM-stages 1 to 3 (equivalent to no, moderate and extensive ACM) were found in 63 (57.8%), 36 (33.0%) and 10 (9.2%) of patients without and 3 (2.8%), 23 (21.1%) and 83 (76.1%) of patients with LAA-thrombi. Atrial contractile function decreased from ACM-stages 1 to 3 (LAA-flow velocities 38 ± 16 cm/s, 31 ± 15 cm/s and 21 ± 12 cm/s; p < 0.0001), while the likelihood for LAA-thrombus increased (2.8%, 21.1% and 76.1%, p < 0.001). Multivariable analysis confirmed an independent odds ratio for LAA-thrombus of 24.6 (p < 0.001) per ACM-stage. Two-year survival free of stroke/TIA, hospitalization for heart failure, myocardial infarction or all-cause death was strongly reduced in ACM-stage 3 (53.8%) compared to no or moderate ACM (82.8% and 84.7%, respectively; p < 0.0001). Electrocardiographic diagnosis of ACM identifies patients with atrial contractile dysfunction and atrial thrombi at risk for adverse cardiovascular outcomes and death.

Acute hemodynamic effects of right and left ventricular lead positions during the implantation of cardiac resynchronization therapy defibrillators.

BACKGROUND: To evaluate the acute hemodynamic effects of different right (RV) and left ventricular (LV) pacing sites in patients undergoing the implantation of a cardiac resynchronization therapy defibrillator (CRT-D). METHODS: Stroke volume index (SVI), assessed via pulse contour analysis, and dp/dt max, obtained in the abdominal aorta, were analyzed in 21 patients with New York Heart Association class III heart failure and left bundle branch block (mean ejection fraction of 24 ± 6%), scheduled for CRT-D implantation under general anesthesia. We compared the hemodynamic effects of RV apical (A), RV septal (B), and biventricular pacing using the worst (lowest SVI; C) and best (highest SVI; D) coronary sinus lead positions. RESULTS: Mean arterial pressure, SVI, and dp/dt max did not differ significantly between RV apical and septal pacing. Dp/dt max and SVI increased significantly during biventricular pacing (dp/dt max: B, 588 ± 160 mmHg/s; C, 651 ± 218 mmHg/s, P = 0.03 vs B; D, 690 ± 220 mmHg/s, P = 0.02 vs C; SVI: B, 33.6 ± 5.5 mL/m², C, 34.8 ± 6.1 mL/m², P = 0.08 vs B, D 36.0 ± 6.0 mL/m², P < 0.001 vs C). The best hemodynamic response was associated with lateral or inferior lead positions in 15 patients. Other LV lead positions were most effective in six patients. CONCLUSIONS: The optimal LV lead position varies significantly among patients and should be individually determined during CRT-D implantation. The impact of the RV stimulation site in patients with intraventricular conduction delay, undergoing CRT-D implantation, has to be investigated in further studies.

Direct Versus Side Graft Cannulation From the Right Axillary Artery in Thoracic Aortic Surgery.

BACKGROUND: The axillary artery can be cannulated for antegrade cerebral perfusion directly or by employing a prosthetic vascular graft anastomosed to the artery. METHODS: From 2008 until 2019, 688 patients underwent axillary artery cannulation. Of those, 287 underwent direct cannulation and 401 cannulation through a side graft. We identified risk factors for cannulation-related complications, and after propensity score matching, we compared the 2 matched cohorts' cannulation-related and postoperative outcomes. RESULTS: A smaller axillary-artery diameter (odds ratio = 0.70; 95% confidence interval, 0.56-0.87) and emergency surgery (odds ratio = 2.23; 95% confidence interval, 1.27-3.92) were identified as risk factors for cannulation-associated complications. In the propensity score-matched cohorts (n = 266 in each), the number of patients experiencing cannulation-related complications was significantly higher in the direct cannulation group than in the side-graft group (n = 33 [12.4%] versus n = 15 [5.6%]; P = .01). The direct group's incidence of iatrogenic axillary artery dissection was significantly higher (n = 17 [6.4%] versus n = 4 [1.5%] P = .008); their incidence of postoperative stroke was also significantly higher (n = 39 [14.7%] versus n = 21 [7.9%]; P = .025). Patients cannulated with a side graft needed more transfusions of blood products (median [IQR]: 3.0 [1.0-6.0] versus 4.0 [2.0-7.0;] P = .009). CONCLUSIONS: Cannulating the right axillary through a vascular prosthetic graft reduces cannulation-related complications such as iatrogenic axillary artery dissection and lowers stroke rates. To help prevent cannulation-related complications and stroke, we recommend the routine use of a side graft when cannulating the axillary artery.

Pressure-guided cryoballoon isolation of the pulmonary veins for the treatment of paroxysmal atrial fibrillation.

BACKGROUND: Pulmonary vein (PV) isolation using a balloon-mounted cryoablation system is a new technology for the percutaneous treatment of atrial fibrillation (AF). Complete PV occlusion during balloon ablation has been shown to predict successful electrical isolation. The aim of this study was to correlate mechanical PV occlusion with changes in a pressure curve recorded at the distal tip of the cryoballoon catheter. METHODS AND RESULTS: We analyzed 51 PVs in 12 patients (61 +/- 6 years old) with paroxysmal AF. At first, PV occlusion via the cryoballoon was documented by changes in the pressure curve. Once the PV is occluded, the pressure curve registered in the vein converts from a left atrial pressure curve to a pulmonary artery pressure curve: the PV wedge curve. Occlusion was then confirmed by transesophageal echocardiography (TEE). Following 2 cryoablation applications, electrical PV isolation was assessed with a circumferential mapping catheter. Under the exclusive guidance of changes in the pressure curve at the tip of the cryoballoon, mechanical occlusion confirmed by TEE was achieved in 47 of 51 PVs (92%). Three PVs required further TEE guidance to achieve occlusion. All 50 occluded veins were electrically isolated after cryoablation. One right inferior vein, which could not be occluded with the balloon, displayed conduction post cryoablation and was isolated by focal ablation. CONCLUSIONS: Occlusion and electrical isolation of PVs during cryoballoon ablation can be predicted by the appearance of a PV wedge curve at the tip of the catheter. This new straightforward parameter may facilitate the procedure.

Accuracy of stroke volume variation compared with pleth variability index to predict fluid responsiveness in mechanically ventilated patients undergoing major surgery.

BACKGROUND AND OBJECTIVE: Accurate assessment of a patient's volume status is an important goal for an anaesthetist. However, most variables assessing fluid responsiveness are either invasive or technically challenging. This study was designed to compare the accuracy of arterial pressure-based stroke volume variation (SVV) and variations in the pulse oximeter plethysmographic waveform amplitude as evaluated with the noninvasive calculated pleth variability index (PVI) with central venous pressure to predict the response of stroke volume index (SVI) to volume replacement in patients undergoing major surgery. METHODS: We studied 20 patients scheduled for elective major abdominal surgery. After induction of anaesthesia, all haemodynamic variables were recorded immediately before (T1) and subsequent to volume replacement (T2) by infusion of 6% hydroxy-ethyl starch (HES) 130/0.4 (7 ml kg) at a rate of 1 ml kg min. RESULTS: The volume-induced increase in SVI was at least 15% in 15 patients (responders) and less than 15% in five patients (nonresponders). Baseline SVV correlated significantly with changes in SVI (DeltaSVI; r = 0.80; P < 0.001) as did baseline PVI (r = 0.61; P < 0.004), whereas baseline values of central venous pressure showed no correlation to DeltaSVI. There was no significant difference between the area under the receiver operating characteristic curve for SVV (0.993) and PVI (0.973). The best threshold values to predict fluid responsiveness were more than 11% for SVV and more than 9.5% for PVI. CONCLUSION: Although arterial pressure-derived SVV revealed the best correlation to volume-induced changes in SVI, the results of our study suggest that both variables, SVV and PVI, can serve as valid indicators of fluid responsiveness in mechanically ventilated patients undergoing major surgery.

Methemoglobinemia in critically ill patients during extended hemodialysis and simultaneous disinfection of the hospital water supply.

INTRODUCTION: To evaluate the cause of methemoglobinemia in patients undergoing extended daily hemodialysis/hemodiafiltration we analyzed the relationship between methemoglobinemia and the water disinfection schedule of the hospital. METHODS: We reviewed all arterial blood gas analyses, obtained over a one-year period, in patients undergoing extended hemodialysis/hemodiafiltration, and compared the methemoglobin concentrations obtained on the days when the water supply was disinfected, using a hydrogen peroxide/silver ion preparation, with data measured on disinfection-free days. RESULTS: The evaluation of 706 measurements revealed a maximum methemoglobin fraction of 1.0 (0.8; 1.2) % (median and 25th; 75th percentiles) during hemodialysis/hemodiafiltration on the disinfection-free days. The methemoglobin fraction increased to 5.9 (1.3; 8.4) % with a maximal value of 12.2% on the days of water disinfection (P < 0.001 compared to disinfection-free days). Spot checks on hydrogen peroxide concentrations in the water supply, the permeate, and the dialysate, using a semi-quantitative test, demonstrated levels between 10 and 25 mg/l during water disinfection. CONCLUSIONS: Our results demonstrate that even a regular hospital water disinfection technique can be associated with significant methemoglobinemia during extended hemodialysis. Clinicians should be aware of this potential hazard.

Predicted and measured plasma propofol concentration and bispectral index during deep sedation in patients with impaired left ventricular function.

OBJECTIVE: To evaluate the ability of the Schnider pharmacokinetic model to predict plasma propofol concentration during target-controlled propofol infusion in patients with impaired left ventricular function and to investigate the predictive value of the bispectral index (BIS) to indicate deep sedation in this patient group. DESIGN: Prospective, observational study. PARTICIPANTS: Thirty-four patients (mean left ventricular ejection fraction 31% +/- 9%) undergoing the implantation of a cardioverter-defibrillator during deep sedation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Predicted and measured propofol plasma concentrations and BIS were assessed during steady-state conditions with the propofol infusion rate constant for at least 20 minutes. The plasma propofol concentration was significantly underestimated by the pharmacokinetic model used (mean percentage prediction error 37% +/- 49%). The 50% probability of deep sedation was calculated at a predicted propofol concentration of 2.09 (95% confidence interval [CI], 2.04-2.14) mug/mL and at a measured propofol concentration of 2.70 (95% CI, 2.62-2.78) mug/mL. BIS values showed a marked variability among individuals during deep sedation (5th-95th percentiles: 25-81). CONCLUSIONS: The pharmacokinetic model used markedly underestimated propofol plasma levels in the patient group studied. The large variability among patients suggests that BIS monitoring is not suitable for indicating an exact endpoint corresponding to deep sedation.

A clinical comparison of bubble elimination in Quadrox and Polystan oxygenators.

BACKGROUND: Microbubbles generated during heart surgery on extracorporeal circulation have been implicated as a possible cause of postoperative neurocognitive dysfunction and negative outcome. The main sources of microbubbles in the extracorporeal circuit are air leaking from the venous cannulation site, air delivered by drug and volume administration, during the taking of blood samples, during hemofiltration, and by using vacuum-assisted venous drainage (VAVD). Membrane oxygenators, although not designed for the elimination of gaseous microbubbles, can eliminate much of this air. AIM OF THE STUDY / HYPOTHESIS: The aim of this study was to test the hypothesis that the amount of microbubbles passing through the oxygenator varies depending on the oxygenator design. METHODS: one hundred patients undergoing aortic valve replacement with cardiopulmonary bypass (CPB) were included in a retrospective clinical trial assessing the bubble elimination of the two oxygenators routinely used in our clinic. The oxygenators (Quadrox-i Adult / Polystan Safe Maxi) are manufactured with the same hollow-fiber material, but display different designs. Bubbles were detected by a two-channel ultrasound bubble counter. The probes were placed directly at the inlet and the outlet of the oxygenators. The filtration index was calculated by the bubble counter as a measure of the percentage reduction of bubble volume and number. RESULTS: The Quadrox has a significantly higher filtration index (92.3% [89.7; 95.1], median [25(th),75(th) percentile]) than the Polystan (74.9% [64.2;80.9], p<0.001), indicating the superior ability of the Quadrox to eliminate microbubbles. CONCLUSION: Our study demonstrates major differences in the capacity of bubble elimination of the oxygenators being investigated, possibly depending on oxygenator design.

Pulmonary edema after extensive radiofrequency ablation for atrial fibrillation.

BACKGROUND: More extensive ablation strategies for the treatment of atrial fibrillation (AF) have increased success rates but are associated with new and sometimes serious complications. We describe a new complication after extensive radiofrequency (RF) ablation in the left atrium (LA) for persistent AF. METHODS AND RESULTS: Electroanatomic guided circumferential ablation around both ipsilateral pulmonary veins (PV) was performed with the endpoint of complete conduction block. When necessary, supplementary RF applications were added, including ablation of complex fractionated potentials and/or isolation of other thoracic veins and/or linear left atrial lesions. RF energy was delivered via an irrigated tip catheter with a maximum power of 30-35 W. Four out of 120 patients undergoing extensive RF ablation for persistent AF (including two patients with additional LA substrate modification) developed dyspnea, bilateral pulmonary edema, and signs of a systemic inflammatory response syndrome (SIRS) (rise in body temperature, leukocyte count, and C-reactive protein (CRP levels) 18-48 hours after the procedure. There were no signs of PV stenosis, focal lung injury, left ventricular dysfunction, circulatory failure, or infection. All patients had complete recovery with supportive therapy within 3-4 days after the onset of symptoms. CONCLUSIONS: Extensive LA radiofrequency ablation bears the risk of a severe pulmonary edema. Although the precise mechanism is elusive, clinical features point toward a systemic inflammatory response.

Aortic Replacement After TEVAR-Diameter Correction With Modified Use of the Siena Prosthesis.

BACKGROUND: To report a new technique for diameter correction in patients after thoracic endovascular aortic repair (TEVAR) with large stent-grafts using the Vascutek Siena 4-branch collared prosthesis (Vascutek Terumo, Inchinnan, Scotland, UK) in patients undergoing thoracoabdominal (TA) aortic replacement. METHODS: Within a 24-month period, 39 patients underwent TA replacement at our center. Of these, 6 patients had undergone previous TEVAR with large stent-grafts (42 to 48 mm diameter). Indications for TEVAR were aneurysm formation in 3 patients and residual type B aortic dissection (status post repair of type A dissection) in 3 patients. In these patients, the Vascutek Siena 4-branch prosthesis was used in a reversed fashion, removing the elephant trunk portion and using the sewing collar for diameter correction at the anastomotic site. RESULTS: No 30-day mortality and no stroke or symptomatic spinal cord ischemia was observed. Median diameter of the TEVAR graft at the anastomotic site was 44 mm. Median size of the Siena graft used was 26 mm. Diameter correction was successfully achieved in all patients by tailoring the sewing collar of the Siena 4-branch prosthesis to the individual need according to the diameter of the distal end of the stent-graft. CONCLUSIONS: Using the sewing collar of the Vascutek Siena 4-branch prosthesis for diameter correction in patients undergoing TA replacement after previous TEVAR with large stent-grafts adds a useful adjunct to the armamentarium of options in a growing patient population.

The Duration of the Amplified Sinus-P-Wave Identifies Presence of Left Atrial Low Voltage Substrate and Predicts Outcome After Pulmonary Vein Isolation in Patients With Persistent Atrial Fibrillation.

OBJECTIVES: Left atrial (LA) low-voltage substrate (LVS) potentially slows intra-atrial conduction, which might identify patients at risk for arrhythmia recurrence following pulmonary vein isolation (PVI). BACKGROUND: Up to 50% of patients with persistent atrial fibrillation (AF) have arrhythmia recurrence following PVI, mostly due to arrhythmogenic LA LVS. METHODS: Seventy-two patients with persistent AF underwent electrocardioversion to sinus rhythm and high-density voltage mapping of the left atrium. Invasively measured LA activation time and P-wave duration (PWD; total PWD and LA PWD [measured from -dV/dt in leads V1 and V2 until the end of the P-wave]) on amplified (40 to 50 mm/mV, 100 to 200 mm/s) digitized 12-lead electrocardiography (ECG) were compared with the extent of LA LVS (<0.5 and <1. 0mV). Freedom from arrhythmia following PVI was evaluated in 143 patients with persistent AF stratified according to amplified PWD before ablation. RESULTS: LA LVS resulted in regional conduction delay, which increased LA activation time (r = 0.79). LA PWD strongly correlated with LA activation time (r = 0.96) and LA LVS (r = 0.80). As the first (right atrial) portion of the P-wave (from P-wave beginning until -dV/dt in leads V1 and V2) was not affected by LA LVS, total PWD correlated with LA LVS (r = 0.84). PWD ≥150 ms identified advanced LA LVS with 94.3% sensitivity and 91.7% specificity. One-year arrhythmia freedom following PVI-only was significantly higher in patients with PWD <150 ms (n = 73) compared with those with prolonged PWD ≥150 ms (n = 70) (72.0% vs. 40.8%; p = 0.003). CONCLUSIONS: Advanced arrhythmogenic LVS is associated with significant intra-atrial conduction delay, which is accurately measurable by prolongation of PWD on amplified 12-lead ECG. PWD ≥150 ms during sinus rhythm measured prior to ablation identifies patients with persistent AF who are at increased risk for arrhythmia recurrence following PVI.