Systemic Blood Pressure Trends and Antihypertensive Utilization Following Continuous-Flow Left Ventricular Assist Device Implantation: an Analysis of the Interagency Registry for Mechanically Assisted Circulatory Support

Background: Elevated systemic blood pressure (SBP) has been linked to complications in Continuous-flow left ventricular assist devices (CF-LVADs), including stroke and pump thrombosis. We queried Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) to describe the response of SBP to CF-LVAD implantation and to delineate contemporary trends in antihypertensive (AH) utilization for patients with these pumps. Methods: We identified all CF-LVAD implantations in patients older than 18 years from 2006-2014, excluding those whose durations were less than 30 days. Pre-implant patient demographics and characteristics were obtained for each record. SBPs [i.e., mean arterial pressures (MAPs)], AH-use data, and vital status were tabulated, extending up to 5 years following implantation. Results: A total of 10,329 CF-LVAD implantations were included for study. Post-implant, SBPs increased rapidly during the first 3 months but plateaued thereafter; AH utilization mirrored this trend. By 6 months, mean MAPs climbed 12.2% from 77.6 mmHg (95% CI: 77.4-77.8) pre-implantation to 87.1 mmHg (95% CI: 86.7-87.4) and patients required a mean of 1.8 AH medications (95% CI: 1.75-1.78) -a 125% increase from AH use at 1-week post-implantation (0.8 AHs/patient, 95% CI: 0.81-0.83) but a 5.3% decrease from pre-implant utilization (1.9 AHs/patient, 95% CI: 1.90-1.92). Once medication changes stabilized, the most common AH regimens were lone beta blockade (15%, n=720) and a beta blocker plus an ACE inhibitor (14%, n=672). Conclusions: SBP rises rapidly after CF-LVAD implantation, stabilizing after 3 months, and is matched by concomitant changes in AH utilization; this AH use has increased over consecutive implant years

Minithoracotomy for mitral valve repair improves inpatient and postdischarge economic savings

ObjectiveSmall series of thoracotomy for mitral valve repair have demonstrated clinical benefit. This multi-institutional administrative database analysis compares outcomes of thoracotomy and sternotomy approaches for mitral repair.MethodsThe Premier database was queried from 2007 to 2011 for mitral repair hospitalizations. Premier contains billing, cost, and coding data from more than 600 US hospitals, totaling 25 million discharges. Thoracotomy and sternotomy approaches were identified through expert rules; robotics were excluded. Propensity matching on baseline characteristics was performed. Regression analysis of surgical approach on outcomes and costs was modeled.ResultsExpert rule analysis positively identified thoracotomy in 847 and sternotomy in 566. Propensity matching created 2 groups of 367. Mortalities were similar (thoracotomy 1.1% vs sternotomy 1.9%). Sepsis and other infections were significantly lower with thoracotomy (1.1% vs 4.4%). After adjustment for hospital differences, thoracotomy carried a 17.2% lower hospitalization cost (−$8289) with a 2-day stay reduction. Readmission rates were significantly lower with thoracotomy (26.2% vs 35.7% at 30 days and 31.6% vs 44.1% at 90 days). Thoracotomy was more common in southern and northeastern hospitals (63% vs 37% and 64% vs 36%, respectively), teaching hospitals (64% vs 36%) and larger hospitals (>600 beds, 78% vs 22%).ConclusionsRelative to sternotomy, thoracotomy for mitral repairs provides similar mortality, less morbidity, fewer infections, shorter stay, and significant cost savings during primary admission. The markedly lower readmission rates for thoracotomy will translate into additional institutional cost savings when a penalty on hospitals begins under the Affordable Care Act's Hospital Readmissions Reduction Program

Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.

Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection

Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches.

Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program

Minimally Invasive Mitral Valve Surgery II: Surgical Technique and Postoperative Management.

Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery

Low Temperature Epitaxy Growth and Kinetic Modeling of SiGe for BiCMOS Application

There is an ambition of continuously decreasing thermal budget in CMOS and BiCMOS processing, thus low temperature epitaxy (LTE) (350-650°C) with chemical vapor deposition (CVD) technique in order to have faster process with low cost. One of the growth issues at low temperatures is gas quality where the oxygen and moisture contamination becomes critical for the epilayers quality. If the level amount of contamination is not controlled, the silicon dioxide islands are formed and the oxygen level in the film will be high. This thesis is focused on two different aspects of "LTE". The first focus of this thesis was to identify the effect of contamination on the strain and quality of the SiGe epilayers (prior and during epitaxy). The samples in this study were exposed to different oxygen and moisture partial pressures (2ppb-250 ppm range) at different exposure temperatures (350-650°C). The results revealed that presence of contamination even at low ranges (2-100 ppb) is not negligible and affects the strain. Parameters such as O2 exposure temperature and partial pressure, and SiGe layer’s growth temperature impacted the oxygen level and strain in the films. For oxygen levels below 100 ppb, High Resolution Scanning Microscopy (HRSEM) could not detect very small oxide island. By increasing the O2 partial pressure well above 100 ppb, the oxide islands are saturated at 0.08 μm2. The second focus of this thesis was to model the Si2H6/Ge2H6-based epitaxial growth of SiGe. The model can predict the number of free sites on Si surface, growth rate of Si and SiGe, and the Ge content at low temperature. A good agreement between the model and the experimental data is found. This model can provide the required growth parameters for certain layer profile which is vital to decrease the total number of growth runs for calibration and cause to reduce the total fabrication cost

Silicon Carbide Technology for High- and Ultra-High-Voltage Bipolar Junction Transistors and PiN Diodes

Silicon carbide (SiC) is an attractive material for high-voltage and high-temperature electronic applications owing to the wide bandgap, high critical electric field, and high thermal conductivity. High- and ultra-high-voltage silicon carbide bipolar devices, such as bipolar junction transistors (BJTs) and PiN diodes, have the advantage of a low ON-resistance due to conductivity modulation compared to unipolar devices. However, in order to be fully competitive with unipolar devices, it is important to further improve the off-state and on-state characteristics, such as breakdown voltage, leakage current, common-emitter current gain, switching, current density, and ON-resistance. In order to achieve a high breakdown voltage with a low leakage current, an efficient and easy to fabricate junction edge protection or termination is needed. Among different proposed junction edge protections, a mesa design integrated with junction termination extensions (JTEs) is a powerful approach. In this work, implantation-free 4H-SiC BJTs in two classes of voltage, i.e., 6 kV-class and 15 kV-class with an efficient and optimized implantation-free junction termination (O-JTE) and multiple-shallow-trench junction termination extension (ST-JTE) are designed, fabricated and characterized. These terminations result in high termination efficiency of 92% and 93%, respectively. The 6 kV-class BJTs shows a maximum current gain of β = 44. A comprehensive study on the geometrical design is done in order to improve the on-state performances. For the first time, new cell geometries (square and hexagon) are presented for the SiC BJTs. The results show a significant improvement of the on-state characteristics because of a better utilization of the base area. At a given current gain, new cell geometries show a 42% higher current density and 21% lower ON-resistance. The results of this study, including an optimized fabrication process, are utilized in the 15 kV-class BJTs where a record high current gain of β = 139 is achieved. Ultra-high-voltage PiN diodes in two classes of voltage, i.e., 10+ kV using on-axis 4H-SiC and 15 kV-class off-axis 4H-SiC, are presented. O-JTE is utilized for 15 kV-class PiN diodes, while three steps ion-implantation are used to form the JTE in 10+ kV PiN diodes. Carbon implantation followed by high-temperature annealing is also performed for the 10+ kV PiN diodes in order to enhance the lifetime. Both type diodes depict conductivity modulation in the drift layer. No bipolar degradation is observed in 10+ kV PiN diodes.QC 20161209</p

Optimal Emitter Cell Geometry in High Power 4H-SiC BJTs

Three 4H-SiC bipolar junction transistor designs with different emitter cell geometries (linear interdigitated fingers, square cell geometry, and hexagon cell geometry) are fabricated, analyzed, and compared with respect to current gain, ON-resistance (R-ON), current density (J(C)), and temperature performance for the first time. Emitter size effect and surface recombination are investigated. Due to a better utilization of the base area, optimal emitter cell geometry significantly increases the current density about 42% and reduces the ON-resistance about 21% at a given current gain, thus making the device more efficient for high-power and high-temperature applications.QC 20151106</p