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OBJECTIVES Despite promising short- and mid-term results for durability of the Trifecta valve, contradictory reports of early structural valve deterioration (SVD) do exist. We investigated the incidence of SVD after surgical aortic valve replacement (SAVR) with the Trifecta in our single-centre experience. METHODS Data of 347 consecutive patients (mean age 71.6 ± 9.5 years, 63.4% male) undergoing SAVR with the Trifecta between 2011 and 2017 were analysed. Clinical and echocardiographic reports were obtained with a median follow-up of 41 months (1114 patient years). RESULTS Isolated SAVR was performed in 122 patients (35.2%), whereas 225 patients (64.8%) underwent concomitant procedures. The median EuroSCORE II was 4.0 (0.9; 7.1) and 30-day mortality was 3.7% (n = 13). Kaplan–Meier estimates for the freedom of overall mortality at 1, 5 and 7 years were 88.7 ± 1.7%, 73.7 ± 2.6% and 64.7 ± 4.2%, respectively. SVD was observed in 25 patients (7.2%) with a median time to first diagnosis of 73 months. Freedom of SVD was 92.5 ± 0.9% at 5 years and 65.5 ± 7.1% at 7 years. Thirteen patients underwent reintervention for SVD (6 re-SAVR, 7 valve-in-valve), resulting in a freedom of reintervention for the SVD of 98.5 ± 1.1% at 5 years and 76.9 ± 6.9% at 7 years. CONCLUSIONS We herein report one of the highest rates of SVD after SAVR with the Trifecta. These data indicate that the durability of the prosthesis decreases at intermediate to long-term follow-up, leading to considerable rates of reintervention due to SVD.

Background There is a high coincidence of significant coronary artery disease and severe aortic stenosis. Coronary revascularization should be performed prior to transcatheter aortic valve implantation (TAVI). We report a case of non-ST-elevation myocardial infarction (NSTEMI) after complex percutaneous coronary intervention (PCI) prior to TAVI, where differential diagnosis between coronary stent failure and bioprosthesis-related sinus obstruction was substantial. Case summary A 79-year-old woman was re-admitted to the hospital 5 days after TAVI due to troponin-negative new-onset angina. She underwent complex PCI 3 days before TAVI and was not compliant to medications. Symptoms initially resolved after re-establishment of anti-hypertensive treatment. There were no signs of aortic bioprosthesis failure, paravalvular leak, or myocardial ischaemia. After 1 month, the symptoms re-occurred. Due to elevated troponins, myocardial ischaemia in electrocardiogram and new contractility disorders, NSTEMI was diagnosed. Because it was impossible to intubate the left coronary artery (LCA), cardiac surgery was performed. Calcified native coronary leaflet was pushed by the stent frame of aortic bioprosthesis towards LCA ostium causing its subtotal occlusion. Transcatheter heart valve (THV) was removed and the new surgical aortic bioprosthesis was implanted. Further hospitalization and 1-month follow-up were uneventful. Discussion Pre-procedural assessment is crucial prior to THV interventions. Delayed coronary obstruction caused by the native leaflet is extremely rare and potentially fatal complication of TAVI. The diagnosis is difficult and high clinical suspicion is required to detect this pathology. Given our experience, the indication towards interventional or surgical repair should be established faster to avoid coronary ischaemia.

OBJECTIVES A 3-dimensionally (3D) engineered model for simulation of aortic valve and proximal aortic procedures is a reliable tool both for training young surgeons and for simulating complex cases. To achieve a realistic simulation, the artificial model should reproduce the angles and orientations of the cardiac structures based on the patient’s anatomical condition, reproduce tissue mechanical characteristics and be easy to obtain and easy to use. The goal of the study was the production and validation of realistic training models, based on the patient’s actual anatomical characteristics, to provide training for aortic valve procedures. METHODS An anatomical model was manufactured using 3D printing and silicone casting. The digital anatomical model was obtained by segmenting computed tomography imaging. The segmented geometrical images were processed and a casting mould was designed. The mould was manufactured on a 3D printer. Silicone was cast into the mould; after curing, the finished model was ready. The realistic reproduction was evaluated by mechanical hardness tests and a survey by cardiac surgeons. RESULTS Six 3D silicone models were produced that represented the patient’s anatomy including aortic valve leaflets, aortic root with coronary ostia, ascending aorta and proximal arch. Aortic valve replacement was performed, and 100% of the participants evaluated the model in a survey as perfectly reproducing anatomy and surgical handling. CONCLUSIONS We produced a realistic, cost-effective simulator for training purposes and for simulation of complex surgical cases. The model reproduced the real angulation and orientation of the aortic structures inside the mediastinum, permitting a real-life simulation of the desired procedure. This model offers opportunities to simulate various surgical procedures.

Pump thrombosis (PT) is a serious adverse event in patients receiving left ventricular assist devices (LVAD). The study aims to determine whether pump parameters and clinical data may enable early detection of PT. This retrospective study included 88 patients who received an LVAD between 2012 and 2015 among which those with intra-PT were identified. In a propensity score-matched control group observation, time periods were matched with time before thrombosis. International normalized ratio (INR) time in therapeutic range (TTR) and lactate dehydrogenase (LDH) were analyzed for 60 days preceding PT. Furthermore, pump data (power, flow, and speed) in HeartWare ventricular assist devices (HVAD) patients were analyzed 7 days before PT using a mixed-design analysis of variance to investigate temporal changes in pump data. Pump thrombosis occurred in 15 patients (13 males, age 58 ± 10 years, 7 HeartMate II and 8 HVAD). International normalized ratio therapeutic range (2.0-3.0) and acetylsalicylic acid daily doses (100-200 mg) were similar for both groups, but patients with PT had lower TTR (36% vs. 65%; p = 0.025). No significant difference in LVAD power between groups was seen at baseline (p = 0.31), and power did not change in the control group over time (p > 0.99). Lactate dehydrogenase increased already 1 week prior PT and power from 4.4 ± 0.8 W at baseline to 4.9 ± 0.8 W (p = 0.007) 2 days before readmission and to 6.5 ± 1.8 W (p = 0.015) at readmission. Pump thrombosis is associated with a lower percentage of INR TTR and elevated LDH before the event. A better monitoring of pump parameters would enable PT detection already up to 2 days in advance.

Background: Chronic obstructive pulmonary disease (COPD) is one of the most common disorders in the world. COPD is characterized by airflow obstruction, which is not fully reversible. Patients usually experience breathing-related symptoms with periods of acute worsening and a substantial decrease in the health-related quality-of-life. Active and comprehensive disease management can slow down the progressive course of the disease and improve patients’ disabilities. Technological progress and digitalization of medicine have the potential to make elaborate interventions easily accessible and applicable to a broad spectrum of patients with COPD without increasing the costs of the intervention. Objective: This study aims to develop a comprehensive telemonitoring and hybrid virtual coaching solution and to investigate its effects on the health-related quality of life of patients with COPD. Methods: A monocentric, assessor-blind, two-arm (intervention/control) randomized controlled trial will be performed. Participants randomized to the control group will receive usual care and a CAir Desk (custom-built home disease-monitoring device to telemonitor disease-relevant parameters) for 12 weeks, without feedback or scores of the telemonitoring efforts and virtual coaching. Participants randomized to the intervention group will receive a CAir Desk and a hybrid digital coaching intervention for 12 weeks. As a primary outcome, we will measure the delta in the health-related quality of life, which we will assess with the St. George Respiratory Questionnaire, from baseline to week 12 (the end of the intervention). Results: The development of the CAir Desk and virtual coach has been completed. Recruitment to the trial started in September 2020. We expect to start data collection by December 2020 and expect it to last for approximately 18 months, as we follow a multiwave approach. We expect to complete data collection by mid-2022 and plan the dissemination of the results subsequently. Conclusions: To our knowledge, this is the first study investigating a combination of telemonitoring and hybrid virtual coaching in patients with COPD. We will investigate the effectiveness, efficacy, and usability of the proposed intervention and provide evidence to further develop app-based and chatbot-based disease monitoring and interventions in COPD. © 2020 JMIR Publications. All rights reserved., JMIR Research Protocols, 9 (10), ISSN:1929-0748

Transcatheter aortic valve replacement (TAVR) has rapidly become a viable alternative to the conventional isolated surgical aortic valve replacement (iSAVR) for treating severe symptomatic aortic stenosis. However, data on younger patients is scarce and a gap exists between data-based recommendations and the clinical use of TAVR. In our study, we utilized a machine learning (ML) driven approach to model the complex decision-making process of Heart Teams when treating young patients with severe symptomatic aortic stenosis with either TAVR or iSAVR and to identify the relevant considerations. Out of the considered factors, the variables most prominently featured in our ML model were congestive heart failure, established risk assessment scores, previous cardiac surgeries, a reduced left ventricular ejection fraction and peripheral vascular disease. Our study demonstrates a viable application of ML-based approaches for studying and understanding complex clinical decision-making processes.

Technological progress of left ventricular assist devices (LVADs) towards rotary blood pumps and the optimization of medical management contributed to the significant improvements in patient survival as well as LVAD support duration. Even though LVAD therapy is now well-established for end-stage heart failure patients, the long-term occurrence of adverse events (AE) such as bleeding, infection or stroke, still represent a relevant burden. An early detection of AE, before onset of major symptoms, can lead to further optimization of patient treatment and thus mitigate the burden of AE. Continuous patient monitoring facilitates identification of pathophysiological states and allows anticipation of AE to improve patient management. In this paper, methods, algorithms and possibilities for continuous patient monitoring based on LVAD data are reviewed. While experience with continuous LVAD monitoring is currently limited to a few centers worldwide, the pace of developments in this field is fast and we expect these technologies to have a global impact on the well-being of LVAD patients.

Background: In recent years, the number of people suffering from chronic conditions that require ongoing medical support reaching into the everyday lives of patients is constantly increasing. Global health systems are, however, not adequately equipped for this extraordinarily time-consuming and cost-intensive development. Here, conversational agents (CAs) can offer easily scalable and ubiquitous support. However, different aspects have not yet been sufficiently investigated to fully exploit their potential. One such trait is the interaction style between patients and CAs. In human-to-human settings, the interaction style is an imperative part of the relationship between patients and physicians. The patient-physician interaction is recognized as critical success factor for patient's satisfaction, treatment adherence, and subsequent treatment outcome. However, it remains so far effectively unknown how different interaction styles can be implemented into CA relationships and if these are recognizable by users. Objective: The objective of this paper is to develop an operationalization scheme to induce two specific interaction styles into CA-patient dialogues and subsequently test and validate them in a chronic healthcare context. Methods: Based on the Roter Interaction Analysis System (RIAS) and iterative evaluations by scientific experts and medical healthcare professionals, we identified 15 communication components that characterize the two operationalized interaction styles, i.e., the deliberative and paternalistic interaction style. These communication components were used to develop two CA variations, each representing one of the two interaction styles. We assessed them in an online between-subject experiment. Here, participants were asked to put themselves in the position of a patient suffering from chronic obstructive pulmonary disease (COPD). Participants were randomly assigned to interact with one of the two CAs and subsequently asked to identify the respective interaction style. A chi-square test was used to assess the correct identification of the CA-patient interaction style. Results: 88 individuals (48% female, mean age= 31.5 years) fulfilled the inclusion criteria and participated in the online experiment. Participants in both the paternalistic and deliberative condition correctly identified the underlying interaction style of the CAs in more than 80% of the assessments (X2 (1, 88) = 38.23, P = .000; rφ = .68). The validation of the operationalization scheme was hence successful. Conclusions: We developed an operationalization scheme tailored for a medical context to induce a paternalistic, respectively, deliberative interaction style into a written interaction between a patient and a CA. We successfully tested and validated the operationalization scheme in an online experiment with 88 participants. Future research should implement and test the operationalization scheme with actual chronic patients and compare results between medical conditions. The operationalization scheme can further be used as a starting point to develop dynamic CAs that adapt their interaction style to their users., Journal of Medical Internet Research, 23 (1), ISSN:1438-8871

A 70-year-old female with symptomatic severe native aortic regurgitation, acquired dextrocardia, moderate-to-severe secondary mitral regurgitation and prohibitive surgical risk was admitted for transcatheter aortic valve replacement. A balloon-expendable Sapien 3 Ultra valve was implanted successfully. After 6 months, the patient remained symptomatic due to the concomitant moderate-to-severe secondary mitral regurgitation. Transcatheter mitral valve repair using a Carillon Mitral Contour System was performed resulting in a significant reduction of mitral regurgitation and uneventful follow-up. Most importantly, other transcatheter repair techniques would not have been feasible due to the impossible transoesophageal echocardiography guidance. This is the first case of transcatheter aortic valve replacement in a patient with native aortic regurgitation, acquired dextrocardia and severe aortic annulus malrotation using a balloon-expendable valve. Moreover, it is the first transcatheter mitral valve repair procedure using Carillon device performed by a cardiac surgeon.

OBJECTIVESWe reviewed our institutional experience with outflow graft stenosis (OGS) in 3 contemporary left ventricular assist devices (LVAD).METHODSData from 347 consecutive adult recipients of LVAD [Medtronic HVAD (n = 184, 53.0%), Abbott HeartMate II (n = 62, 17.9%) and Abbott HeartMate 3 (n = 101, 29.1%)] implanted between March 2006 and October 2019 were analysed retrospectively. Primary study end points were the incidence of OGS necessitating treatment and survival on LVAD support.RESULTSDuring the study period, 17 patients (4.9%) developed OGS requiring treatment with a probability of 0.6% at 1 year, 1.9% at 2 years, 3.8% at 3 years, 4.7% at 4 years and 5.9% at 5 years of LVAD support. Notably, in 13.8% of patients, a compression-related narrowing of the outflow graft with a probability of 1.5% at 6 months, 1.8% 1 year, 6.0% at 2 years, 12.3% at 3 years, 15.4% at 4 years and 16.6% at 5 years of LVAD support with no difference between devices (P = 0.26) was observed. There was a trend towards increased risk of mortality with OGS (hazard ratio 2.21, 95% confidence interval 0.87–5.51; P = 0.09). OGS preferentially occurred in segments of the outflow graft covered by a protective coating.CONCLUSIONSOGS is a rare but potentially lethal complication during LVAD support. Modifications of pump design and implant techniques may be needed because OGS preferentially occurs within covered portions of the outflow graft. Systematic screening may be warranted.

Suction of the left ventricle can lead to potentially life‐threatening events in left ventricular assist device (LVAD) patients. With the resolution of currently available clinical LVAD monitoring healthcare professionals are unable to evaluate patients’ suction occurrences in detail. This study investigates occurrences and durations of suction events and their associations with tachycardia in stable outpatients. Continuous high‐resolution LVAD data from HVAD patients were analyzed in the early outpatient period for 15 days. A validated suction detection from LVAD signals was used. Suction events were evaluated as suction rates, bursts of consecutive suction beats, and clusters of suction beats. The occurrence of tachycardia was analyzed before, during, and after suction clusters. Furthermore, blood work, implant strategy, LVAD speed setting, inflow cannula position, left ventricular diameters, and adverse events were evaluated in these patients. LVAD data of 10 patients was analyzed starting at 78 ± 22 postoperative days. Individuals’ highest suction rates per hour resulted in a median of 11% (range 3%‐61%). Bursts categorized as consecutive suction beats with n = 2, n = 3‐5, n = 6‐15, and n > 15 beats were homogenously distributed with 10.3 ± 0.8% among all suction beats. Larger suction bursts were followed by shorter suction‐free periods. Tachycardia during suction occurred in 12% of all suction clusters. Significant differences in clinical parameters between individuals with high and low suction rates were only observed in left ventricular end‐diastolic and end‐systolic diameters (P

Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow change has an impact on the oxygen uptake at peak exercise (pVO2). Cardiac and pump parameters such as LVAD flow rate (Q LVAD), heart rate (HR), and aortic valve (AV) opening were analyzed from continuously recorded LVAD data during physical exercises of maximal (bicycle ergometer test) and submaximal intensities (6‐min walk test and regular trainings). During all exercise sessions, the LVAD speed was kept constant. Cardiac and pump parameter responses of 16 patients for maximal and submaximal intensity exercises were similar for Q LVAD: +0.89 ± 0.52 versus +0.59 ± 0.38 L/min (P = 0.07) and different for HR: +20.4 ± 15.4 versus +7.7 ± 5.8 bpm (P

Monitoring of the interaction between the circulatory system and the pump is essential for postoperative and ambulatory care of VAD patients. VAD monitoring gives important information on hemodynamic changes, patient activity, pump performance, and potential problems. Progress in the fields of clinical monitoring, self-monitoring, and pump monitoring has reduced time from physiological onset of an adverse event to detection and ultimately intervention. Additionally, innovations from the past three decades in the field of automatic physiological pump control strategies show that it is possible to react to fine changes in patient’s hemodynamics automatically, resulting in even tighter pump integration of the VAD with patient’s hemodynamics.

BACKGROUND: Left ventricular assist devices (LVADs) are an established treatment for end stage heart failure patients. As LVADs do not currently respond to exercise demands, attention is also directed towards improvements in exercise capacity and resulting quality of life. The aim of this study was to explore hemodynamic responses observed during maximal exercise tests to infer underlying patient status and therefore investigate possible diagnostics from LVAD derived data and advance the development of physiologically adaptive LVAD controllers. METHODS: High resolution continuous LVAD flow waveforms were recorded from 14 LVAD patients and evaluated at rest and during maximum bicycle exercise tests (n = 24). Responses to exercise were analyzed in terms of an increase (↑) or decrease (↓) in minimum (QMIN), mean (QMEAN), maximum flow (QMAX) and flow pulsatility (QP2P). To interpret clinical data, a cardiorespiratory numerical simulator was used that reproduced patients' hemodynamics at rest and exercise. Different cardiovascular scenarios including chronotropic and inotropic responses, peripheral vasodilation, and aortic valve pathologies were simulated systematically and compared to the patients' responses. RESULTS: Different patients' responses to exercise were observed. The most common response was a positive change of ΔQMIN↑ and ΔQP2P↑ from rest to exercise (70% of exercise tests). Two responses, which were never reported in patients so far, were distinguished by QMIN↑ and QP2P↓ (observed in 17%) and by QMIN↓ and QP2P↑ (observed in 13%). The simulations indicated that the QP2P↓ can result from a reduced left ventricular contractility and that the QMIN↓ can occur with a better left ventricular contractility and/or aortic insufficiency. CONCLUSION: LVAD flow waveforms determine a patients' hemodynamic "fingerprint" from rest to exercise. Different waveform responses to exercise, including previously unobserved ones, were reported. The simulations indicated the left ventricular contractility as a major determinant for the different responses, thus improving patient stratification to identify how patient groups would benefit from exercise-responsive LVAD control. ispartof: PLOS ONE vol:15 issue:3 ispartof: location:United States status: published

Patients supported with a left ventricular assist device (LVAD) have impaired cardiovascular adaptations during exercise, resulting in reduced total cardiac output and exercise intolerance. The aim of this study is to report associations among these impaired cardiovascular parameters and exercise hemodynamics, and to identify in which conditions an LVAD speed increase can provide substantial benefits to exercise. A cardiorespiratory simulator was used to reproduce the average hemodynamics of LVAD patients at exercise. Then, a sensitivity study was conducted where cardiovascular parameters were changed individually ±20% of their baseline value at exercise (heart rate, left/right ventricular contractility, total peripheral resistance, and valve pathologies). Simulations were performed at a baseline LVAD speed of 2700 rpm and repeated at 3500 rpm to evaluate the benefits of a higher LVAD support on hemodynamics. Total cardiac output (TCO) was mostly impaired by a poor left ventricular contractility or vasodilation at exercise (-0.6 L/min), followed by a poor chronotropic response (-0.3 L/min) and by a poor right ventricular contractility (-0.2 L/min). LVAD speed increase better unloads the left ventricle and improves total cardiac output in all the simulated conditions. The most substantial benefits from LVAD speed increase were observed in case of poor left ventricular contractility (TCO + 1.6 L/min) and vascular dysfunction (TCO + 1.4 L/min) followed by lower heart rate (TCO + 1.3 L/min) and impaired right ventricular contractility (TCO + 1.1 L/min). Despite the presence of the LVAD, exercise hemodynamic is strongly depending on the ability of the cardiovascular system to adapt to exercise. A poor left ventricular inotropic response and a poor vascular function can strongly impair cardiac output at exercise. In these conditions, LVAD speed increase can be an effective strategy to augment total cardiac output and unload the left ventricle. These results evidence the need to design a physiological LVAD speed controller, tailored on specific patient's needs. ispartof: ARTIFICIAL ORGANS vol:44 issue:3 pages:239-247 ispartof: location:United States status: published

In rotary blood pump recipients with low blood pressure pulsatility, current oscillometric methods to measure blood pressure are not applicable. The aim of this study was to use ultrasonic Doppler flow measurements to determine blood pressure in this patient population noninvasively. In 28 rotary blood pump recipients, blood pressure was measured three times with the developed Doppler method and compared to the invasive arterial line (n = 15) or to the oscillometric Terumo Elemano BP monitor (n = 13). Blood velocities in the radial artery were recorded by the new Doppler sensor during cuff deflation. A sigmoid curve was fitted to a preprocessed velocity signal and the systolic and mean arterial pressures were determined. A total of 84 measurements were performed, and 17 recordings were visually excluded from further analysis due to obvious artifacts. Both the systolic and mean pressures derived by the Doppler method were in good accordance with the invasively measured pressure (3.7 ± 6.6 mmHg for the systolic and −2.1 ± 7.3 mmHg for the mean pressure). A good agreement between the oscillometric monitor and the Doppler method for the systolic (0.0 ± 6.0 mmHg) and mean (1.0 ± 5.9 mmHg) pressures was observed. In this study, a new Doppler blood pressure measurement system was developed and clinically validated. The novel sensor allows easier placement above the radial artery compared to commercial probes. An algorithm was developed which processes the Doppler signal robustly and is able to determine the systolic as well as the mean arterial blood pressure.

Background: Younger patients with severe symptomatic aortic stenosis are a particularly challenging collective with regard to the choice of intervention. High-risk patients younger than 75 years of age are often eligible for both the transcatheter aortic valve replacement (TAVR) and the isolated surgical aortic valve replacement (iSAVR). Data on the outcomes of both interventions in this set of patients are scarce. Methods: One hundred and forty-four propensity score-matched patients aged 75 years or less who underwent TAVR or iSAVR at the Hietzing Heart Center in Vienna, Austria, were included in the study. The mean age was 68.9 years (TAVR 68.7 vs. SAVR 67.6 years, p = 0.190) and the average EuroSCORE II was 5.4% (TAVR 4.3 [3.2%] vs. iSAVR 6.4 (4.3%), p = 0.194). Results: Postprocedural adverse event data showed higher rates of newly acquired atrial fibrillation (6.9% vs. 19.4%, p = 0.049), prolonged ventilation (2.8% vs. 25.0%, p &lt, 0.001) and multi-organ failure (0% vs. 6.9%) in the surgical cohort. The in-hospital and 30-day mortality was significantly higher for iSAVR (1.4% vs. 13.9%, p = 0.012, 12.5% vs. 2.8%, p = 0.009, respectively). The long-term survival (median follow-up 5.0 years (2.2–14.1 years)) of patients treated with the surgical approach was superior to that of patients undergoing TAVR (p &lt, 0.001). Conclusion: Although the survival analysis revealed a higher in-hospital and 30-day survival rate for high-risk patients aged ≤75 years who underwent TAVR, iSAVR was associated with a significantly higher long-term survival rate.

Left Ventricular Assist Devices are an established treatment option for end-stage heart failure. However, the therapy is still burdened with a high incidence of adverse events. Excessive unloading of the ventricle, also called “suction” has previously been identified as potentially related to worse outcome. In this study, suction was automatically detected without additional sensors in a database of 38 patients who were implanted with the Medtronic HVAD device, containing 500 snapshots with 6258 individual cardiac cycles. A set of 4 classifiers based on 87 features in a wide range of complexities was developed and evaluated, with particular focus on the interpatient variations. The supervised-learning algorithms were trained on the pooled annotation of 6 experts. Analysis was performed on two scales: per-beat -and per-snapshot analysis. A single feature classifier could perform on a similar level to more complex algorithms on a per-snapshot basis (Test sensitivity: 100% specificity: 95.5%). An adaptively boosted tree ensemble classifier managed to achieve higher accuracy on a per-beat basis, but showed signs of overfitting with a reduction in performance from 100% (Interquartile Range (IQR) 0%) in the training dataset to a median sensitivity of 92.5% (IQR 3%) and a median specificity of 100% (IQR 5%) in the testing dataset. The proposed algorithms provide an essential part in assessing the correct level of unloading for the patient, and may be used in different use cases, either as a diagnostic marker, or as a component of an automatic physiological controller.

Left ventricular assist devices (LVADs) assure longer survival to patients, but exercise capacity is limited compared to normal values. Overall, LVAD patients show high wedge pressure and low cardiac output during maximal exercise, a phenomenon hinting at the need for increased LVAD support. Clinical studies investigating the hemodynamic benefits of an LVAD speed increase during exercise, ended in inhomogeneous and sometimes contradictory results. The native ventricle-LVAD interaction changes between rest and exercise, and this evolution is complex, multifactorial and patient-specific. The aim of this paper is to provide a comprehensive overview on the patient-LVAD interaction during exercise and to delineate possible therapeutic strategies for the future. A computational cardiorespiratory model was used to simulate the hemodynamics of peak bicycle exercise in LVAD patients. The simulator included the main cardiovascular and respiratory impairments commonly observed in LVAD patients, so as to represent an average hemodynamic response to exercise. In addition, other exercise responses were simulated, by tuning the chronotropic, inotropic and vascular functions, and implementing aortic regurgitation and stenosis in the simulator. These profiles were tested under different LVAD speeds and LVAD pressure-flow characteristics. Simulations output showed consistency with clinical data from the literature. The simulator allowed the working condition of the assisted ventricle at exercise to be investigated, clarifying the reasons behind the high wedge pressure and poor cardiac output observed in the clinics. Patients with poorer inotropic, chronotropic and vascular functions, are likely to benefit more from an LVAD speed increase during exercise. Similarly, for these patients, a flatter LVAD pressure-flow characteristic can assure better hemodynamic support under physical exertion. Overall, the study evidenced the need for a patient-specific approach on supporting exercise hemodynamics. In this frame, a complex simulator can constitute a valuable tool to define and test personalized speed control algorithms and strategies. ispartof: ANNALS OF CARDIOTHORACIC SURGERY vol:10 issue:3 pages:339-352 ispartof: location:China status: published

Purpose LVAD outflow graft stenosis (OGS) is increasingly recognized after left ventricular assist device implantation. We analyzed our institutional experience with (OGS) in order to better understand the clinical significance and treatment options for this new form of pump pathology. Methods We retrospectively reviewed our institutional experience with OGS in patients with contemporary centrifugal LVAD. Study endpoint were incidence and outcomes of LVAD OGS. Results From March 2006 to October 2019, 284 consecutive patients (183 (64.4%) HVAD and 101 (35.6%) HeartMate3) underwent primary LVAD implantation. Median follow up was 456 (range 1-2921) days. OGS was identified in 17 patients (total incidence 5.0%, 95% CI 3.5%-9.4%; HVAD: 5.5%, 95% CI 2.7%-9.8% vs. HeartMate3 6.9%, 95% CI 2.8%-13.8%, p=0.611). Median time to OGS development was 911 (range 281-2811) days. In all cases, OGS was located within covered segments of the outflow graft (bend relief (Heartmate 3 only) or protective Gore-Tex cover). In 13 patients (76.5%) OGS impaired LVAD flow and necessitated interventions (surgical revision n=2, endovascular stent placement n=9, surgery after failed stent placement n=1, death before intervention n=1). Two patients (11.8%) died following intervention and outflow graft stenosis recurred in two patients (11.8%) after initially successful treatment. Kaplan-Meier estimate of survival free from outflow graft stenosis is depicted on Figure 1. Conclusion Outflow graft stenosis is a potentially lethal late complication of LVAD implantation. Surgical or interventional treatment is indicated when LVAD flows are impaired. Modification of pump design may be warranted as outflow graft stenosis preferentially occur in covered portions of outflow grafts.

Continuous flow left ventricular assist devices (cfLVADS) result in a significant reduction in aortic valve (AV) opening, which has been associated with several complications. Reliable monitoring of AV opening is needed to determine whether pump speed adjustment may be able to minimize adverse outcomes. We assessed AV status continuously by echocardiography for 4 minutes in 3 states in 18 HeartWare HVAD patients: 2 minutes at rest, and 1 minute each following Valsalva maneuver and supine leg-raising. Using a previously described algorithm, beat-to-beat AV status was compared with the area under the curve of the normalized power spectral density analysis (PSD-AUC) for the corresponding beats of the pump speed waveform. Five thousand five hundred twenty-seven beats were analyzed. AV opening varied between 0% and 100% for the cohort with the median AV opening frequency 21.5%, and median duration of opening of 124 msec (range 0-279). The receiver operating characteristic (ROC) curve area for AV opening by the PSD-AUC algorithm was 0.95 (P < 0.0001). A PSD-AUC cut-off of 0.82 distinguished between an open and closed AV with 86% sensitivity and 93% specificity. Accuracy was similar in regular cardiac rhythm, atrial fibrillation or with frequent ventricular ectopic beats. Valsalva maneuver and leg-raising had no impact on accuracy. The PSD-AUC was strongly predictive of AV opening duration (P < 0.0001). We found that AV status and opening duration can be determined with high accuracy on a beat-to-beat basis irrespective of cardiac rhythm and with low level exercise and changes in filling.

Nitrogen (N) losses from agriculture are negatively impacting groundwater, air, and surface water quality. National, state, and local policies and procedures that can mitigate these problems are needed. Market-based approaches where waste treatment plants (point sources) can purchase nutrient credits from upstream agricultural operations (non-point sources) to meet their National Pollutant Discharge Elimination System permit requirements within the Clean Water Act are being explored. This paper reviews these market-based approaches for enhancing air and water quality at a lower cost than simple command-and-control regulation, and describes new tools that are being developed, such as Nitrogen Trading Tool (NTT), that can be used to assess nitrogen losses to the environment under different management scenarios. The USDA-NRCS, EPA and several other state and local agencies are interested in these new tools. The NTT, though primarily designed for water quality markets, also estimates savings in nitrous oxide (N 2 O) emissions that can be traded in carbon markets. For example, an analysis using NTT shows that for 100 ha of crop land, a C sequestration equivalent of approximately 25–38 Mg C y −1 for a farm in Ohio, and 13–21 Mg C y −1 for a farm in Virginia could be achieved with better nitrogen management practices. These numbers across a watershed could be much larger with improved N and conservation management practices that contribute to better water quality and lower global warming potential. There is a need to further develop, calibrate, and validate these tools to facilitate nitrogen and carbon trading future markets around the globe to increase environmental conservation across agro-ecosystems worldwide.

Nitrogen (N) losses from agriculture often contribute to reduced air, groundwater, and surface water quality. The minimization of these N losses is desirable from an environmental standpoint, and a recent interest in discounted reductions of agricultural N losses that might apply to a project downstream from an agricultural area has resulted in the concept of N credits and associated N trading. To help quantify management-induced reductions in N losses at the farm field level (essential components of a Nitrogen Trading Tool), we defined a Nitrogen Trading Tool difference in reactive N losses (NTT-DNL"r"e"a"c) as the comparison between a baseline and new management scenarios. We used a newly released Windows XP version of the Nitrogen Losses and Environmental Assessment Package (NLEAP) simulation model with Geographic Information System (GIS) capabilities (NLEAP-GIS) to assess no-till systems from a humid North Atlantic US site, manure management from a Midwestern US site, and irrigated cropland from an arid Western US site. The new NTT-DNL"r"e"a"c can be used to identify the best scenario that shows the greatest potential to maximize field-level savings in reactive N for environmental conservation and potential N credits to trade. A positive NTT-DNL"r"e"a"c means that the new N management practice increases the savings in reactive N with potential to trade these savings as N credits. A negative number means that there is no savings in reactive N and no N available to trade. The new NLEAP-GIS can be used to quickly identify the best scenario that shows the greatest potential to maximize field-level savings in reactive N for environmental conservation and earning N credits for trade.

Background Both iatrogenic coronary artery stenosis early after aortic valve replacement and pseudonormalization of inverted T-waves in acute ischemia are rare but well-recognized findings which coincide in this case. Case presentation 10 weeks after aortic valve replacement, a 58-year-old male patient was readmitted with recent onset of unstable angina pectoris. Electrocardiography showed inverted T-waves in leads V2-4 with pseudonormalization during episodes of typical chest pain. Coronary angiography revealed subtotal ostial occlusion of the left anterior descending artery which was successfully treated by percutaneous coronary intervention. Conclusion Iatrogenic coronary artery stenosis is a potentially life-threatening complication that can occur early after aortic valve replacement in patients with normal preoperative coronary angiography. T-wave-pseudonormalization during episodes of angina pectoris may lead to misinterpretation in patients at high risk.

Objective: To assess midterm results after aortic valve replacement (AVR) with an autologous tissue cardiac valve (ATCV). This new technique was developed to construct a tissue prosthesis for AVR using the patients pericardium, harvested at the time of operation with negligible effect on operating time. Methods: Briefly, glutaraldehyde tanned pericardium is mounted on a stent requiring no suturing. Between March 1994 and December 1996, 87 patients, 44/43 M/F and aged 70 ^ 6 years had AVR for aortic stenosis (80%), aortic insufficiency (6%) and combined lesions (14%), one patient suffered from endocarditis. Additional coronary artery bypass was done in 25%, aortic root enlargement in 7%. Aortic cross clamp and cardiopulmonary bypass times were 69 ^ 21 and 93 ^ 29 min. All patients were followed by clinical examination and color flow Doppler echocardiography in 3‐12 months interval. Follow up was 99% complete. Results: There were five perioperative deaths (6%), none of them valve related. Eighty-one patients were followed up to a period of 52 months (mean interval 37:5 ^ 1:3 months), one patient was lost for follow up. Overall survival was 86, 81, 79 and 71% at 12, 24, 36 and 48 months, respectively. There were 14 late deaths with eight (10%) valve related (four cerebral deaths, four sudden deaths). Sixteen patients (20%) had to be re-operated due to severe valve incompetence. Freedom from reoperation was 98, 97, 90 and 63% at 12, 24, 36, and 48 months, respectively. Valve incompetence occurred suddenly, without previous signs in the follow-up examinations. Selection and preparation of the pericardium, the way of fixation of the tissue ‐ brief immersion in glutaraldehyde ‐ and engineering problems might be responsible for this disastrous outcome. Conclusion: Due to these results we must state, that the ATCV did not fulfill our expectations and presently we can not recommend it as an aortic valve substitute. q 1999 Elsevier Science B.V. All rights reserved.

Bilateral nephrectomy for treatment of refractory hypertension in chronic hemodialyzed patients has been infrequently carried out. We analyzed the benefits of this operation on blood pressure, clinical state, drug treatment, and quality of life. In 10 hemodialyzed patients with refractory hypertension, systolic (SBP) and diastolic (DBP) blood pressure were measured 1 month before nephrectomy bilateral and 3, 6, 9, and 12 months after. In addition, the use of antihypertensive drugs before and after surgery was evaluated. Four patients had SBP and DBP values characteristic of malignant hypertension. In all 10 patients hypertension responded neither to reduction of plasma volume by ultrafiltration nor to multiple antihypertensive drug therapy. Hypertensive crises were associated with cerebral hemorrhage in two patients, severe encephalopathy with persistent neural dysfunction in one patient, and encephalopathy and diplopia in another. Three months after bilateral nephrectomy blood pressure decreased significantly (P < .005) and was normal in nine patients. In one noncompliant patient with intradialytic body weight increases of nearly 10%, blood pressure was still elevated. Malignant or drug-resistant hypertension with hypertensive crises is an indication for bilateral nephrectomy. The clinical state and quality of life improved in all patients in the present study and antihypertensive treatment is no longer necessary.

(abridged) We describe an image-comparison technique of Heidemann and Ritter that uses image compression, and is capable of: (i) detecting novel textures in a series of images, as well as of: (ii) alerting the user to the similarity of a new image to a previously-observed texture. This image-comparison technique has been implemented and tested using our Astrobiology Phone-cam system, which employs Bluetooth communication to send images to a local laptop server in the field for the image-compression analysis. We tested the system in a field site displaying a heterogeneous suite of sandstones, limestones, mudstones and coalbeds. Some of the rocks are partly covered with lichen. The image-matching procedure of this system performed very well with data obtained through our field test, grouping all images of yellow lichens together and grouping all images of a coal bed together, and giving a 91% accuracy for similarity detection. Such similarity detection could be employed to make maps of different geological units. The novelty-detection performance of our system was also rather good (a 64% accuracy). Such novelty detection may become valuable in searching for new geological units, which could be of astrobiological interest. The image-comparison technique is an unsupervised technique that is not capable of directly classifying an image as containing a particular geological feature; labeling of such geological features is done post facto by human geologists associated with this study, for the purpose of analyzing the system's performance. By providing more advanced capabilities for similarity detection and novelty detection, this image-compression technique could be useful in giving more scientific autonomy to robotic planetary rovers, and in assisting human astronauts in their geological exploration and assessment., Comment: 27 pages, 3 figures, 2 tables, accepted for publication in the International Journal of Astrobiology

Objective: The advantages of the aortic valve homograft-high resistance to infective endocarditis, low risk of thromboembolism, low gradient and excellent long term results are well known. Trying to extend these advantages to a greater number of patients, we used pulmonary homografts as aortic valve substitute, based on the experimental evidence, that they can withstand the higher stress in systemic circulation. Methods: From September 1988 to August 1994 175 patients (103 men, 72 women, mean age 61.75±12.92 years) underwent aortic valve replacement with a cryopreserved pulmonary homograft. All valves were taken from our own homograft bank. They were inserted freehand intraaortically, 162 in subcoronary position, 13 as intraaortic cylinder. All patients were followed clinically and by colorflow Doppler echocardiography in 3-12 month intervals. Results: Patients, 8, died perioperatively (4.57%). None of the deaths was valve related. Patients, 2, had to be reoperated during the perioperative period due to severe valvular incompetence 165 patients were followed up to a period of 7.5 years (mean interval 3.83±1.45 years). Patients, 30, died, 13 deaths (7.42%) must be regarded as valve related. Patients, 22, (12.52%) had to be reoperated due to severe graft incompetence. Patients, 9 (5.14%), acquired prosthetic endocarditis. Conclusion: Due to our results, high rate of valve related deaths, high rate of graft failure and high rate of prosthetic endocarditis, we must state that the pulmonary homograft did not fulfil our expectations and presently we can not recommend it as an aortic valve substitute.

Excellent clinical results with pulmonary autografts and experimental evidence that the pulmonary valve can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 to March 1991, 45 consecutive patients (59.9 +/- 12.0 years, 25 men and 20 women) received a cryopreserved pulmonary allograft in the aortic position from our hospital based valve bank. All allografts were inserted freehand in the subcoronary position. There were 3 in-hospital deaths (7%) and 1 patient had severe valvular incompetence immediately postoperatively requiring reoperation after 4 weeks. Forty-one patients were followed at 3-6 month interval for 14.7 +/- 7.8 months (3-28 months) and valve performance was assessed routinely by means of color flow Doppler echocardiography: 34 patients (83%) had no or trivial aortic valve regurgitation. Valvular incompetence class II was present in 2 patients (5%) whereas 3 (7%) demonstrated class II-III. Severe aortic regurgitation (class III-IV) could be detected in 2 patients (5%). Both had to undergo reoperation 4 months and 15 months, respectively, postoperatively. Macroscopic and histological evaluation of the explanted valves demonstrated absence of significant degeneration. We assume that a mismatch in size between allograft and aortic annulus could have lead to dilatation of the allograft valve ring and consequently to valvular incompetence. Pulmonary cryopreserved allografts achieve acceptable short-term results which can be improved if initial technical problems can be avoided.

A 25-year-old man suffering from sudden onset of haemoptysis after 1 week of orthopnoea, fatigue and general weakness was admitted to a cardiology department in Vienna. No diagnosis was made. Four weeks later cardiopulmonary resuscitation and pericardiocentesis were necessary because of cardiac tamponade. Although all modern imaging procedures were performed, a diagnosis of rapidly progressive primary cardiac angiosarcoma could not be established. Definitive diagnosis was established only after exploratory median sternotomy. The patient exhibited no response to chemotherapy. He died 5 days after surgery as a result of respiratory failure.

Background . Whether aortic homografts (AH) or mechanical devices (MD) are the valves of choice for aortic valve replacement in young patients (age 20 to 50 years) is unclear. Hence, we examined all aortic valve replacements performed with AH and MD in a retrospective study. Methods . Between 1988 and 1995, 45 patients (mean age, 38.6 ± 8.5 years) underwent aortic valve replacement with an AH and 40 patients (mean age, 42.0 ± 7.2 years) with an MD. Patients' demographic data were comparable in all respects, except acute endocarditis, which was an absolute indication for the use of an AH. Results . The mean follow-up time was 51.7 ± 22.6 months for AH versus 44.6 ± 26.9 months for MD (not significant). There were significant differences in postoperative outcome among the two groups ( p ≤ 0.05): perioperative death (4 versus 0 for AH and MD, respectively); reoperation (8 for AH versus 0 for MD); and endocarditis (5 versus 0 for AH and MD). There were higher incidences of embolism (2 versus 0) and hemorrhage (2 versus 0) in MD compared with AH. Only late death was comparable among the two groups with 5 patients in each group. Conclusions . The mechanical valves in our midterm follow-up are superior to homografts. However, embolic and hemorrhagic complications in MD are continuously impending and cumulative during a long-term follow-up. The surprisingly high rate of endocarditis in the AH group is only partly caused by the indication: 2 cases were recurrent, but there were also 2 new onsets of endocarditis. In 4 cases structural deterioration was responsible for reoperation. Aortic valve replacement with aortic homografts showed a rather unfavorable midterm outcome in this selected group of young patients. A surprisingly high rate of graft endocarditis and structural deterioration led to subsequent reoperations. Although our results with mechanical valves are satisfying, embolism and hemorrhage are impending risk factors for many years to come in these young patients.

Background The known complications of heterograft bioprostheses and homograft valves have renewed the interest in the use of autologous material. A new technique to construct a tissue prosthesis for aortic valve replacement using the patient's pericardium harvested at the time of operation was developed. The glutaraldehyde-tanned pericardium is mounted on a stent requiring no suturing. Intraoperative testing assures adequate valve function. Methods The autologous tissue cardiac valve was implanted in 50 patients in the aortic position between March 1994 and May 1995. Echocardiograms were performed in all patients before hospital discharge, at 3 months (41 patients), and at the end of first postoperative year (12 patients). The mean age was 69.8 ± 5 years (range, 58 to 82 years). Eighty-four percent of patients presented with aortic stenosis and 16% had a combined lesion. Additional cardiac procedures were performed in 21 patients. Results Aortic cross-clamp time was 72 ± 19 minutes, and bypass time was 97 ± 28 minutes. There were three in-hospital deaths, and 2 patients died within the first postoperative year. Predischarge echocardiography demonstrated excellent hemodynamics, with a mean gradient of 20 ± 8 mm Hg and no or trivial aortic insufficiency in 45 patients. One patient had moderate aortic insufficiency. At first follow-up 36 patients (90%) were in New York Heart Association class I and 4 patients were in class II. Echocardiography showed no evidence of valve failure or degeneration (mean gradient, 17 ± 5 mm Hg; aortic insufficiency=grade 0 [trivial] in 35 patients, grade II in 3 patients, and grade III in 1 patient). Similarly, no degeneration or valve failure with increasing aortic insufficiency was seen in the patients studied at the end of the first postoperative year. Conclusions These results demonstrate that an autologous tissue cardiac valve can be manufactured in the operating room without significant additional operating time. Intraoperative testing minimizes the risk of primary failure with aortic insufficiency. Short-term results are encouraging, with good hemodynamic performance of the valve and no signs of degeneration. However, long-term durability needs to be demonstrated.

From November 1992 to October 1993 we randomized 101 patients over 60 years of age undergoing elective aortic valve replacement, with or without concomitant coronary artery bypass grafting, to receive either a cryopreserved aortic or pulmonary homograft (n = 38) or a stentless porcine aortic valve xenograft (Edwards Prima 2500) (n = 63). The majority of all valves (92%) were inserted freehand in the subcoronary position. Six homografts (16%) were implanted as a free-root replacement and two xenografts (3%) were used as a mini root. There were four in-hospital deaths (4%), three in the homograft group and one in the xenograft group (homograft, 7.9% versus xenograft, 1.6%; p = not significant). Forty-one patients were followed at 3- to 6-month intervals for 9 +/- 2 months (3 to 14 months) and valve pathology was assessed routinely by means of color flow Doppler echocardiography. Two patients in the homograft group developed new aortic insufficiency grade II; all others remained with trivial or no valve incompetence. The mean gradient remained unchanged to immediate postoperative measurements (homograft, 5 +/- 1 mm Hg versus xenograft, 11 +/- 4 mm Hg; p0.001). Despite a slightly higher transvalvular gradient, xenografts achieved excellent initial results when compared to homografts. Ease of implantation and freedom from thromboembolism indicate that xenografts can be an acceptable alternative to homografts, particularly in older patients with small aortic annuli. Long-term studies assessing the durability of the xenograft are necessary for final evaluation.

Excellent clinical results with pulmonary autografts and experimental evidence that pulmonary valves can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 until March 1993, 126 consecutive patients (61 ± 10 years; 74 men and 52 women) underwent aortic valve replacement with a cryopreserved pulmonary allograft. All allografts were inserted freehand in the subcoronary position. There were four in-hospital deaths (3.2%), and 1 patient had severe valvular incompetence immediately postoperatively, requiring reoperation after 4 weeks. One hundred twenty-one patients were followed up in 3- to 6-month intervals for 25.3 ±16.3 months (range, 6 to 66 months), and valve performance was assessed routinely by means of color-flow Doppler echocardiography. Nine patients (7.1%) died during follow-up. Two patients died of multiple septic emboli during bacterial endocarditis, and 1 patient died of a massive stroke. The other 6 patients died of myocardial infarction (4), respiratory insufficiency due to chronic obstructive lung disease (1), and carcinoma (1). Ninety-four patients (78%) had absent or trivial aortic valve regurgitation. Valvular incompetence class II was present in 3 patients (2.5%), whereas 5 others (4%) demonstrated class II to III. Severe aortic regurgita tion (class III or IV) could be detected in 10 patients (8.3%). All underwent reoperation and replacement of the valve with a prosthetic device. Bacterial endocarditis caused graft incompetence in 3 patients, valve degeneration was detected in another 3, and technical mistakes at valve implantation caused valve failure in the other 4. We assume that a mismatch in size between the allograft and the aortic annulus could have led to dilation of the allograft valve ring and consequently to central valvular incompetence in the patients without cusp degeneration. Cryopreserved pulmonary allografts achieve acceptable intermediate-term results, which can be improved if initial technical problems can be avoided. Disturbingly, the incidence of endocarditis in our series was higher than expected.

Between February 1982 and December 1992 we operated on five patients (three men, two women; aged 40 to 70 years) with mycotic aneurysms of the thoracic aorta. One patient had an aneurysm of the ascending aorta, once the aortic arch and in three cases the descending thoracic aorta were involved. In four of the five patients, excision of the aneurysm and in situ reconstruction of the aorta with a Dacron graft was performed, one patient required a Dacron graft repair and aortic valve replacement. We employed deep hypothermia with circulatory arrest (2), extracorporeal circulation (1), an axillofemoral shunt (1) and a centrifugal pump (1) for cerebral and spinal cord protection. One patient died 4 months postoperatively, the other four patients were without recurrent graft infection and are free of symptoms between 20 months and 5 years postoperatively.

Since 1988 an intensive homograft-program has existed at the Linz General Hospital. We have installed an own hospital-based homograft bank, where the allografts, after a 24-hour sterilization-period in an antibiotic solution and a controlled freezing procedure, are stored in liquid nitrogen at -196 degrees C. In 1991 for the first time aortic valve replacement was performed by pulmonary autograft in 23, mainly younger, patients. Essentially our technique conforms with that of D. N. Ross, in the course of which 18 autografts were implanted in subcoronary position and 5 aortic-root replacements were performed. 3 patients died perioperatively, 2 times a severe post-operative bleeding with following hypoxemic brain damage being the cause; 3 more patients had to be rethoracotomized because of postoperative bleedings. All these were attributed to a technical difficulty, which was overcome. In one patient a left-ventricular assist device had to be installed due to a left-ventricular failure, a successful heart transplantation followed on the 8th postoperative day. A follow-up was conducted in all patients every 3 months. In 2 patients a substantial valve incompetence of grade II-III and grade III was detected, all other patients showed no regurgitation of clinical relevance. Despite our initial difficulties it is our opinion that the many advantages-no anticoagulation necessary, no valve sound, less incidence of bacterial endocarditis, and longer durability-do justify this operative procedure.

Objective:Perioperative mortality, prolonged postoperative recovery after the Norwood procedure, and mortality between stage I and stage II might be related to shunt physiology. A right ventricular to pulmonary artery conduit offers a banded physiology in contrast to a Blalock-Taussig shunt. The purpose of this study was to assess the hemodynamic differences and their consequences in the postoperative course between Norwood patients with a Blalock-Taussig shunt and those with a right ventricular to pulmonary artery conduit.MethodsFrom October 1999 until May 2002, 32 unselected consecutive patients underwent a Norwood procedure at the General Hospital Linz. The first 18 patients received a Blalock-Taussig shunt. In the remaining 14 patients we performed a right ventricular to pulmonary artery conduit. Both groups were compared.ResultsThe diastolic blood pressure was significantly higher in the right ventricular to pulmonary artery conduit group (P < .001). Despite a higher FIO2, PO2 levels tended to be lower in the first 5 postoperative days. At the age of 3 months, catheterization labora- tory data showed a lower Qp/Qs ratio in the same group (0.86 [0.78; 1] versus 1.55 [1.15; 1.6]; P = .005) and a higher dp/dt (955 [773; 1110] vs 776 [615; 907]; P = .018). (Descriptive data reflect medians and quartiles [in brackets].) Hospital survival was 72% in the Blalock-Taussig shunt group versus 93% in the right ventricular to pulmonary ar- tery conduit group. Mortality between stage I and stage II was 23% in the Blalock-Taussig shunt group versus 0% in the right ventricular to pulmonary artery conduit group.ConclusionsA higher diastolic blood pressure and a lower Qp/Qs ratio were associated with a more stable and efficient circulation in patients with a right ventricular to pulmonary artery conduit. More intensive ventilatory support was necessary during the first postoperative days. We did not note any adverse effects of the ventriculotomy on ventricular performance.