Dark Energy Survey Year 1 Results: Cosmological Constraints from Cluster Abundances, Weak Lensing, and Galaxy Correlations.

We present the first joint analysis of cluster abundances and auto or cross-correlations of three cosmic tracer fields: galaxy density, weak gravitational lensing shear, and cluster density split by optical richness. From a joint analysis (4×2pt+N) of cluster abundances, three cluster cross-correlations, and the auto correlations of the galaxy density measured from the first year data of the Dark Energy Survey, we obtain Ω_{m}=0.305_{-0.038}^{+0.055} and σ_{8}=0.783_{-0.054}^{+0.064}. This result is consistent with constraints from the DES-Y1 galaxy clustering and weak lensing two-point correlation functions for the flat νΛCDM model. Consequently, we combine cluster abundances and all two-point correlations from across all three cosmic tracer fields (6×2pt+N) and find improved constraints on cosmological parameters as well as on the cluster observable-mass scaling relation. This analysis is an important advance in both optical cluster cosmology and multiprobe analyses of upcoming wide imaging surveys.

Cosmological Constraints from Multiple Probes in the Dark Energy Survey.

The combination of multiple observational probes has long been advocated as a powerful technique to constrain cosmological parameters, in particular dark energy. The Dark Energy Survey has measured 207 spectroscopically confirmed type Ia supernova light curves, the baryon acoustic oscillation feature, weak gravitational lensing, and galaxy clustering. Here we present combined results from these probes, deriving constraints on the equation of state, w, of dark energy and its energy density in the Universe. Independently of other experiments, such as those that measure the cosmic microwave background, the probes from this single photometric survey rule out a Universe with no dark energy, finding w=-0.80_{-0.11}^{+0.09}. The geometry is shown to be consistent with a spatially flat Universe, and we obtain a constraint on the baryon density of Ω_{b}=0.069_{-0.012}^{+0.009} that is independent of early Universe measurements. These results demonstrate the potential power of large multiprobe photometric surveys and pave the way for order of magnitude advances in our constraints on properties of dark energy and cosmology over the next decade.

What Is the Best Proximal Anastomosis for the Free Right Internal Thoracic Artery during Bilateral Internal Thoracic Artery Revascularization? A Prospective, Randomized Study.

Objective. Bilateral internal thoracic artery (BITA) grafting provides improved graft patency and potential survival advantage in selected patients as compared to single left internal thoracic artery (LITA) revascularization. The ideal functional BITA configuration remains controversial. Methods. Patients undergoing planned BITA revascularization with greater than 75% stenosis in both the left anterior descending artery (LAD) and in a circumflex branch were prospectively randomized to one of two proximal free right internal thoracic artery (RITA) connections directly off the aorta (Ao) (n = 12) or as a "t" graft off the LITA (t) (n = 12). The LITA was placed to the LAD in all cases, and the RITA was placed to a single lateral wall vessel. Intraoperative transit time flow measurements of all arterial grafts were performed, and RITA fractional flow parameters were compared between the 2 groups. Results. There were no differences in preoperative patient variables between the two groups. Cross-clamp times (91.5 + 15.3 versus 68.0 + 12.5 minutes, P < 0.01) and total cardiopulmonary bypass times (109.0 + 16.2 versus 85.0 + 15.1 minutes, P < 0.01) were shorter in the t group. The Ao group demonstrated significantly higher mean RITA flow (38.3 ± 13.5 versus 22.1 ± 9.5, P < 0.01), mean RITA conductance (flow/mean arterial pressure) (0.45 ± 0.16 versus 0.28 ± 0.11, P < 0.01), RITA fractional flow (0.52 ± 0.15 versus 0.36 ± 0.11, P < 0.01), and RITA fractional conductance (0.51 ± 0.15 versus 0.36 ± 0.11, P < 0.01) than the "t" grafted patients. Thirty-day mortality and wound infection were 0% for each group. Over an average of 42.8 + 6.6 months of followup there were no mortalities in either group. Repeat angiography were performed in 4 patients (33%) in the Ao group and 2 patients in the t group (16%). One occluded RITA graft and one ostial RITA stenosis were detected in the Ao group. Conclusions. Acute flow measurements indicate that the free RITA anastomosed to the aorta provides more acute fractional RITA flow than composite "t" grafting to the LITA. Longer-term angiographic and clinical followup are necessary to determine the consequences of these acute hemodynamic findings.

Low adhesion, non-wetting phosphonate self-assembled monolayer films formed on copper oxide surfaces.

Self-assembled monolayer (SAM) films have been formed on oxidized copper (Cu) substrates by reaction with 1H,1H,2H,2H-perfluorodecylphosphonic acid (PFDP), octadecylphosphonic acid (ODP), decylphosphonic acid (DP), and octylphosphonic acid (OP) and then investigated by X-ray photoelectron spectroscopy (XPS), contact angle measurement (CAM), and atomic force microscopy (AFM). The presence of alkyl phosphonate molecules, PFDP, ODP, DP, and OP, on Cu were confirmed by CAM and XPS analysis. No alkyl phosphonate molecules were seen by XPS on unmodified Cu as a control. The PFDP/Cu and ODP/Cu SAMs were found to be very hydrophobic having water sessile drop static contact angles of more than 140 degrees , while DP/Cu and OP/Cu have contact angles of 119 degrees and 76 degrees , respectively. PFDP/Cu, ODP/Cu, DP/Cu, and OP/Cu SAMs were studied by friction force microscopy, a derivative of AFM, to better understand their micro/nanotribological properties. PFDP/Cu, ODP/Cu, and DP/Cu had comparable adhesive force, which is much lower than that for unmodified Cu. ODP/Cu had the lowest friction coefficient followed by PFDP/Cu, DP/Cu, and OP/Cu while unmodified Cu had the highest. XPS data gives some indication that a bidentate bond forms between the alkyl phosphonate molecules and the oxidized Cu surface. Hydrophobic phosphonate SAMs could be useful as corrosion inhibitors in micro/nanoelectronic devices and/or as promoters for anti-wetting, low adhesion surfaces.

Chemical stability of nonwetting, low adhesion self-assembled monolayer films formed by perfluoroalkylsilanization of copper.

A self-assembled monolayer (SAM) has been produced by reaction of 1H,1H,2H,2H-perfluorodecyldimethylchlorosilane (PFMS) with an oxidized copper (Cu) substrate and investigated by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), friction force microscopy (FFM), a derivative of AFM, and contact angle measurement. FFM showed a significant reduction in the adhesive force and friction coefficient of PFMS modified Cu (PFMS/Cu) compared to unmodified Cu. The perfluoroalkyl SAM on Cu is found to be extremely hydrophobic, yielding sessile drop static contact angles of more than 130 degrees for pure water and a "surface energy" (which is proportional to the Zisman critical surface tension for a Cu surface with 0 rms roughness) of 14.5 mJm2(nMm). Treatment by exposure to harsh conditions showed that PFMS/Cu SAM can withstand boiling nitric acid (pH=1.8), boiling water, and warm sodium hydroxide (pH=12, 60 degrees C) solutions for at least 30 min. Furthermore, no SAM degradation was observed when PFMS/Cu was exposed to warm nitric acid solution for up to 70 min at 60 degrees C or 50 min at 80 degrees C. Extremely hydrophobic (low surface energy) and stable PFMS/Cu SAMs could be useful as corrosion inhibitors in micro/nanoelectronic devices and/or as promoters for antiwetting, low adhesion surfaces or dropwise condensation on heat exchange surfaces.

The importance of independent risk-factors for long-term mortality prediction after cardiac surgery.

The purpose of the present study was to determine independent predictors for long-term mortality after cardiac surgery. The European System for Cardiac Operative Risk Evaluation (EuroSCORE) was developed to score in-hospital mortality and recent studies have shown its ability to predict long-term mortality as well. We compared forecasts based on EuroSCORE with other models based on independent predictors. Medical records of patients with cardiac surgery who were discharged alive (n = 4852) were retrospectively reviewed. Their operative surgical risks were calculated according to EuroSCORE. Patients were randomly divided into two groups: training dataset (n = 3233) and validation dataset (n = 1619). Long-term survival data (mean follow-up 5.1 years) were obtained from the National Death Index. We compared four models: standard EuroSCORE (M1); logistic EuroSCORE (M2); M2 and other preoperative, intra-operative and post-operative selected variables (M3); and selected variables only (M4). M3 and M4 were determined with multivariable Cox regression analysis using the training dataset. The estimated five-year survival rates of the quartiles in compared models in the validation dataset were: 94.5%, 87.8%, 77.1%, 64.9% for M1; 95.1%, 88.0%, 80.5%, 64.4% for M2; 93.4%, 89.4%, 80.8%, 64.1% for M3; and 95.8%, 90.9%, 81.0%, 59.9% for M4. In the four models, the odds of death in the highest-risk quartile was 8.4-, 8.5-, 9.4- and 15.6-fold higher, respectively, than the odds of death in the lowest-risk quartile (P < 0.0001 for all). EuroSCORE is a good predictor of long-term mortality after cardiac surgery. We developed and validated a model using selected preoperative, intra-operative and post-operative variables that has better discriminatory ability.

Alkylphosphonate modified aluminum oxide surfaces.

The surface properties of aluminum, such as chemical composition, roughness, friction, adhesion, and wear, can play an important role in the performance of micro-/nano-electromechanical systems, e.g., digital micromirror devices. Aluminum substrates chemically reacted with octadecylphosphonic acid (ODP/Al), decylphosphonic acid (DP/Al), and octylphosphonic acid (OP/Al) have been investigated and characterized by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM). XPS analysis confirmed the presence of alkylphosphonate molecules on ODP/Al, DP/Al, and OP/Al. No phosphonates were found on bare Al as a control. The sessile drop static contact angle of pure water on ODP/Al and DP/Al was typically more than 115 degrees and on OP/Al typically less than 105 degrees indicating that all phosphonic acid reacted Al samples were highly hydrophobic. The root-mean-square surface roughness for ODP/Al, DP/Al, OP/Al, and bare Al was less than 15 nm as determined by AFM. The surface energy for ODP/Al and DP/Al was determined to be approximately 21 and 22 mJ/m2, respectively, by the Zisman plot method, compared to 25 mJ/m2 for OP/Al. ODP/Al and OP/Al were studied by friction force microscopy, a derivative of AFM, to better understand their micro-/nano-tribological properties. ODP/Al gave the lowest coefficient of friction values while bare Al gave the highest. The adhesion forces for ODP/Al and OP/Al were comparable.

Phosphonate self-assembled monolayers on aluminum surfaces.

Substrates of aluminum (Al) deposited by physical vapor deposition onto Si substrates and then chemically reacted with perfluorodecylphosphonic acid (PFDPAlSi), decylphosphonic acid (DPAlSi), and octadecylphosphonic acid (ODPAlSi) were studied by x-ray photoelectron spectroscopy (XPS), contact angle measurements, atomic force microscopy (AFM), and friction force microscopy, a derivative of AFM, to characterize their surface chemical composition, roughness, and micro-/nanotribological properties. XPS analysis confirmed the presence of perfluorinated and nonperfluorinated alkylphosphonate molecules on the PFDPAlSi, DPAlSi, and ODPAlSi. The sessile drop static contact angle of pure water on PFDPAlSi was typically more than 130 degrees and on DPAlSi and ODPAlSi typically more than 125 degrees indicating that all phosphonic acid reacted AlSi samples were very hydrophobic. The surface roughness for PFDPAlSi, DPAlSi, ODPAlSi, and bare AlSi was approximately 35 nm as determined by AFM. The surface energy for PFDPAlSi was determined to be approximately 11 mNm by the Zisman plot method compared to 21 and 20 mNm for DPAlSi and ODPAlSi, respectively. Tribology involves the measure of lateral forces due to friction and adhesion between two surfaces. Friction, adhesion, and wear play important roles in the performance of micro-/nanoelectromechanical systems. PFDPAlSi gave the lowest adhesion and coefficient of friction values while bare AlSi gave the highest. The adhesion and coefficient of friction values for DPAlSi and ODPAlSi were comparable.

AFM structural study of the molecular chaperone GroEL and its two-dimensional crystals: an ideal "living" calibration sample.

Supramolecular complexes, such as chaperonins, are suitable samples for atomic force microscope structural studies because they have a very well defined shape. High-resolution images can be made using tapping mode in liquid under native conditions. Details about the two-dimensional structures formed onto the surface upon adsorption and of the single protein can be observed. Dissection of the upper ring of the supramolecular complex as a result of the applied lateral force through scanning tip is observed. Finally, the combination of lateral convolution and tip penetration into the cavity of chaperonins offers a direct evaluation of the tip convolution effect on images of macromolecular samples.

Imaging the native structure of the chaperone protein GroEL without fixation using atomic force microscopy.

Most sample preparation methods for scanning probe or electron microscopy require that biomolecules, such as proteins, be fixed. Fixation destroys the molecular functionality and can possibly affect the true molecular structure. Here we report sample preparation conditions that allow the imaging of an unfixed protein, GroEL, under in-vivo conditions, by atomic force microscopy. Under these conditions, the protein should maintain its native structure and biological activity. The typical toroidal shape with pore of the GroEL complex was easily visible in the images. Images of a single complex show dimensions that agree well with crystallographic data. Under in-vivo conditions, it should be possible to study the biological activity and function of proteins.

Surgical alternatives to transplantation and assist devices in the treatment of heart failure.

It is estimated that in the United States 30,000 patients with end-stage heart disease are eligible for heart transplantation, although less than 2500 are actually performed each year. As the population ages, several thousand other patients who are ineligible for cardiac transplantation will be left with limited options. Surgical strategies aimed at halting the progression of heart failure have therefore been devised. High-risk coronary artery bypass grafting can improve ejection fraction and alleviate heart failure symptoms in appropriately selected patients. Mitral valve repair and ventricular aneurysm resection/plication procedures may improve heart failure by decreasing the volume load on the left ventricle. Myoreduction operations (Batista operation) aim to improve the volume and wall stress relationship of the dilated left ventricle, but their clinical application has remained experimental.

Retinoic acid suppresses intimal hyperplasia and prevents vessel remodeling following arterial injury.

Vitamin A and its derivatives (retinoids) are capable of inhibiting vascular smooth muscle cell proliferation in vitro. The present study examines the effect of two retinoids, all-trans retinoic acid and 13-cis retinoic acid, on intimal hyperplasia following arterial injury. After receiving varying doses of all-trans retinoic acid or 13-cis retinoic acid, 78 male Sprague-Dawley rats underwent standard balloon catheter denudation of the left common carotid artery. Morphometric analysis and immunohistochemistry for proliferating cell nuclear antigen was performed at early and late time points. Intimal/medial ratios were reduced in a dose-dependent fashion for animals treated with all-trans retinoic acid (P = 0.001) and 13-cis retinoic acid (P = 0.004). Proliferating cell nuclear antigen labeling indices were reduced after treatment with all-trans retinoic acid and 13-cis retinoic acid at early time points post-injury. At a dose of 10 mg/kg, both all-trans retinoic acid and 13-cis retinoic acid inhibited vessel remodeling as measured by increases in luminal diameter (P < 0.05) and external elastic lamina (P < 0.05). Retinoids are an attractive clinical option for the treatment of restenosis following angioplasty and arterial surgery.

A comparative study of colloidal particles as imaging standards for microscopy.

Colloidal particles have long been used as imaging standards for electron microscopy and, more recently, for scanning probe microscopy. We have analysed gold, polystyrene and silica colloidal particles by both transmission electron microscopy and atomic/scanning force microscopy in an attempt to determine if any can be truly used as 'standards' of shape and/or size. From the transmission electron micrographs, we have obtained precise information of the particle circumference and mean diameter. By comparing the ratio of these to the value for pi, we obtained a measure of the sphericity of the particles. We have also shadowed the particles with metal at a known angle and have analysed the shadow length to determine the particles' heights and shapes. The height information obtained from the shadow length data collected from the transmission electron micrographs was then compared with that obtained by atomic/scanning force microscopy. Our results show that cleaned (washed) silica or polystyrene particles closely approach true spheres. In the case of gold particles, height data obtained from shadow lengths analysed in transmission electron micrographs show good agreement with that obtained from the atomic/scanning force microscopy images even without washing. However, the gold particles often deviate from sphericity. Based upon both the shape and the physical properties of the colloidal particles, silica would be the best choice as a standard. We also have noticed that metal shadowing of colloidal particle samples used for atomic/scanning force microscopy offers an advantage which we call a 'nanoscale metric' visible in the image directly at each particle site. This information can be important if one wishes to use samples prepared from colloidal particles simply and reliably to determine the probe shape for scanning probe microscopy from image deconvolution/restoration methods or as a calibration sample.

Improved survival rates support left ventricular assist device implantation early after myocardial infarction.

OBJECTIVES: Implantation of left ventricular assist devices (LVADs) early after acute myocardial infarction (MI) has traditionally been thought to be associated with high mortality rates due to technical limitations and severe end-organ dysfunction. At some experienced centers, doctors have refrained from earlier operation after MI to allow for a period of hemodynamic and end-organ stabilization. METHODS: We retrospectively investigated the effect of preoperative MI on the survival rates of 25 patients who received a Thermocardiosystems Incorporated LVAD either <2 weeks (Early) (n = 15) or >2 weeks (Late) (n = 10) after MI. Outcome variables included perioperative right ventricular assistance (and right-sided circulatory failure), hemodynamic indexes, percent transplanted or explanted, and mortality. RESULTS: No statistically significant differences were demonstrated between demographic, perioperative or hemodynamic variables between the Early and Late groups. Patients in the Early group demonstrated a lower rate of perioperative mechanical right ventricular assistance, but had a higher rate of perioperative inhaled nitric oxide use. In addition, 67% of patients in the Early group survived to transplantation and 7% to explantation, findings comparable to those in the Late group (60% and 0% respectively). CONCLUSIONS: This clinical experience suggests that patients may have comparable outcomes whether implanted early or late after acute MI. These data therefore support the early identification and timely application of this modality in post-MI LVAD candidates, as this strategy may also reveal a subgroup of patients for whom post-MI temporary LVAD insertion may allow for full ventricular recovery.

Inhaled nitric oxide improves hemodynamics in patients with acute pulmonary hypertension after high-risk cardiac surgery.

Severe pulmonary hypertension and right-sided circulatory failure (RSCF) represent an increasing cause of morbidity and mortality in patients undergoing high-risk cardiac surgery. Increased pulmonary vascular resistance in the setting of cardiopulmonary bypass (CPB) may further lead to decrease blood flow across the pulmonary vascular bed; thereby decreasing left ventricular filling and cardiac output. Current management techniques for RSCF include both nonspecific vasodilator and inotropic agents (often limited by systemic hypotension) and the placement of right ventricular assist devices (associated with increased perioperative morbidity). Inhaled nitric oxide (NOi) represents a novel, specific pulmonary vasodilator that has been proven efficacious in these clinical settings. We evaluated 34 patients in 38 operations who underwent cardiac surgery at Columbia Presbyterian Medical Center, and who received NOi (20 ppm) through a modified ventilatory circuit for hemodynamically significant elevations in pulmonary vascular resistance. Nine patients underwent cardiac transplantation, three patients bilateral lung transplantation, 16 patients left ventricular assist device placement and 10 patients routine cardiac surgery. Patients receiving NOi exhibited substantial reductions in mean pulmonary artery pressure (mPAP) (34.6 +/- 2.0 to 26.0 +/- 1.7 mmHg, p < 0.0001), with improvements in systemic hemodynamics, mean arterial pressure (68 +/- 3.1 to 75.9 +/- 2.0 mmHg, p = 0.006). In five cases, patients could not be weaned from CPB until NOi was administered. Patients were maintained on NOi from 6 to 240 h postoperatively (median duration 36 h). Inhaled NO induces substantial reductions in mPAP and increases in both cardiac index and systemic blood pressure in patients displaying elevated pulmonary hemodynamics after high-risk cardiac surgery. NO is, therefore, a useful adjunct in these patients in whom acute pulmonary hypertension threatens right ventricular function and hemodynamic stability.

Complementary surgical/interventional techniques for nonresective management of "inoperable" aneurysms: a second look.

Induced thrombosis ("nonresective" therapy) of aortic aneurysms by distal arterial ligation, coil/wire embolization, and extraanatomic bypass was devalued by anecdotal reports emerging during the mid-1980s. Nevertheless, we have recently found the technique to be life-saving in occasional cases and worth revisiting. Since 1990, standard aortic aneurysm repair has been performed in 231 patients (99.1% survival), endovascular aortic aneurysm repair in 6 patients (83.3% survival), and combined surgical/interventional "nonresective" repair of a variety of aneurysms in 10 patients (100% survival). Mean age of the group was 67.9 years. Repair was performed for aortoiliac aneurysms (4), common iliac aneurysms (3), internal iliac aneurysms (2), and a large proximal subclavian artery pseudoaneurysm (1). Four of the patients had been explored and declared to be "inoperable" (retroperitoneal fibrosis) prior to transfer to the Columbia-Presbyterian Medical Center. All patients survived. Aneurysm rupture has not occurred in any patient, but one patient with a presumably thrombosed subclavian pseudoaneurysm presented 26 months postcoil-induced thrombosis with progressive aneurysm enlargement due to incomplete aneurysm thrombosis and required repair using circulatory arrest. Eight of the patients remain alive (80%) at a mean follow-up of 40.3 months (range 14-88 months). Two patients died of malignancy (30 months) and cardiac disease (15 months). It is concluded that combined surgical/interventional techniques can be life-saving in the rare instances when conventional or endovascular aneurysm repair is not advisable but that complete aneurysm thrombosis is essential and occasionally difficult to achieve. Since small proximal portions of the aneurysm may remain patent and not be visualized on magnetic resonance imaging (MRI) or computed tomography (CT) scans, contrast angiographic documentation of complete aneurysm thrombosis is essential prior to hospital discharge and close follow-up is necessary to ascertain long-term adequacy of the repair. Incomplete thrombosis is suspected as a major factor in earlier reports of aneurysm rupture after seemingly successful nonresective therapy.

Lung reduction operation and resection of pulmonary nodules in patients with severe emphysema.

BACKGROUND: Severe pulmonary dysfunction has been considered a relative contraindication to surgical resection in patients with solitary pulmonary nodules. We report our initial experience with the combined use of lung volume reduction operation and tumor resection in this patient population. METHODS AND PATIENTS: Between January 1995 and July 1996, 14 patients underwent combined lung volume reduction operation and pulmonary nodule resection. Ten (71%) patients were oxygen dependent, 5 (36%) had a room air partial pressure of carbon dioxide > or = 45, and 5 (36%) were steroid dependent preoperatively. Mean preoperative pulmonary function tests included a forced expiratory volume in 1 second of 680 +/- 98 mL (24% +/- 5% predicted), forced vital capacity of 54% +/- 5% predicted, and a forced expiratory volume in 1 second to vital capacity ratio of 37% +/- 2% predicted. RESULTS: Sixteen lesions were resected in the 14 patients and included 9 non-small cell carcinomas. There was one postoperative death. All other patients are alive and well through a mean follow-up of 22.6 +/- 2.3 months (12 to 35 months). At 6-month follow-up improvements were noted in dyspnea index, forced expiratory volume in 1 second forced vital capacity, and 6-minute walk distance. Mediastinal recurrence at 12-month follow-up developed in 1 patient with two separate bronchioalveolar carcinomas. CONCLUSIONS: Simultaneous lung volume reduction operation and tumor resection should be considered in patients with emphysema with marginal reserve in the hope of maximizing postoperative lung function.

"Bow-tie" mitral valve repair: an adjuvant technique for ischemic mitral regurgitation.

BACKGROUND: Current techniques of mitral valve repair rely on decreasing valve area to increase leaflet apposition, but fail to address subvalvular dysfunction. A novel repair has been introduced with partial left ventriculectomy, which apposes the anterior leaflet to a corresponding point on the posterior leaflet creating a double-orifice valve, with reported adequate control of mitral regurgitation. METHODS: We started to use the "bow-tie" repair as an adjunct to posterior ring annuloplasty in cases in which mitral regurgitation was not adequately controlled by decreasing mitral valve area (n = 6), or when placement of an annuloplasty ring was impractical (n = 4). Mean follow-up was 336 days (range, 82 to 551 days) with no postoperative deaths. RESULTS: Mitral regurgitation decreased from 3.6+/-0.5 to 0.8+/-0.4 (p < 0.0001), with a concomitant increase in ejection fraction from 33%+/-13% to 45%+/-11% (p = 0.0156) before hospital discharge. Mitral valve area, measured by pressure half-time, decreased from a mean of 2.5+/-0.3 to 2.1+/-0.3 cm2, with a mean transvalvular gradient of 4.5+/-2.0 mm Hg. In patients whose mitral valve was repaired using the bow-tie alone, mitral regurgitation was reduced from 4+, to a trace to 1+. Postoperatively, mitral valve area increased from 1.9 to 2.5 cm2 during exercise, further supporting the concept that this technique preserves mitral valve annular function. CONCLUSIONS: These observations suggest that the bow-tie repair may offer advantages over conventional techniques of mitral valve repair and should be considered as an adjunct, especially in patients with impaired left ventricular function.

Treatment of endstage heart disease with mechanical circulatory assistance.

A great number of patients suffer and die from the sequelae of acute and chronic heart failure each year. Although advances in medical and surgical therapy have benefited many of these patients, the majority suffer from disease refractory to any definitive therapy. For these patients, cardiac transplantation is the only remaining hope. Unfortunately, because of the increasing demand for donor organs in the face of a fixed and limited supply, this option is only available to a small percentage of these patients. Even in patients accepted for transplantation, a significant waiting list mortality has been observed. A variety of ventricular assist devices (VAD) have been developed since the first successful case of mechanical cardiac assistance over 30 years ago. These devices differ in basic mechanical function, method of insertion, and degree of implantability, and thus have different indications and potential applications. While the intra-aortic balloon pump and centrifugal pumps are effective short-term support modalities, extracorporeal and implantable pulsatile devices have been used successfully for long-term support of patients with reversible and non-reversible cardiac failure. These pumps have most commonly been utilized as bridges to transplantation, but increasing clinical experience has supported the notion of long-term mechanical assistance as a definitive therapy for endstage heart disease. While complications, particularly infection and thromboembolism, pose significant challenges and long-term device reliability remains to be fully determined, available implantable devices seem capable of providing effective long-term support. As data is obtained from currently ongoing trials comparing VAD support to medical therapy for endstage heart failure, ethical and economic issues will assume increasing importance.

Implantable left ventricular assist devices provide an excellent outpatient bridge to transplantation and recovery.

OBJECTIVES: Our recent experience with outpatient left ventricular assist device (LVAD) support is presented to demonstrate the possibilities and limitations of long-term outpatient mechanical circulatory assistance. BACKGROUND: The experience with inpatient LVAD support as a bridge to transplantation has proved the efficacy of such therapy in improving circulatory hemodynamic status, restoring normal end-organ function and facilitating patient rehabilitation. With miniaturization of the power supplies and controllers, such mechanical circulatory support can now be accomplished in an outpatient setting. METHODS: Between March 1993 and February 1997, 32 patients (26 male, 6 female, mean [+/-SEM] age 49 +/- 15 years) underwent implantation of the ThermoCardiosystems (TCI) Heartmate vented electric (VE) LVAD. The VE LVAD is powered by batteries worn on shoulder holsters and is operated by a belt-mounted system controller, allowing unrestricted patient ambulation and hospital discharge. RESULTS: Mean duration of support was 122 +/- 26 days (range 3 to 605), with a survival rate to transplantation or explantation of 78%. Nineteen patients were discharged from the hospital on mean postoperative day 41 +/- 4 (range 17 to 68), for an outpatient support time of 108 +/- 30 days (range 2 to 466). Four patients underwent early transplantation and could not participate in the discharge program, and three patients currently await discharge. The complication rate was not statistically different from that encountered in our previous 52 patients with a pneumatic LVAD. CONCLUSIONS: Outpatient LVAD support is safe and provides improved quality of life for patients awaiting transplantation. Wearable and totally implantable LVADs should be studied as permanent treatment options for patients who are not candidates for heart transplantation.