Need For Mechanical Support Research Articles

Bioabsorbable Coronary Stents

Percutaneous coronary intervention (PCI) with bioabsorbable stents has created interest because the need for mechanical support for the healing artery is temporary, and beyond the first few months there are potential disadvantages of a permanent metallic prosthesis. Stents improve immediate outcomes, including profoundly reducing acute vessel occlusion after PCI by scaffolding intimal tissue flaps that have separated from deeper layers and by optimizing vessel caliber. They limit restenosis by preventing negative remodeling.1 The intimal hyperplastic healing response to PCI that contributes to restenosis, especially after bare metal stenting, can be limited by coating stents with antiproliferative medications.2,3 Potential advantages of having the stent disappear from the treated site include reduced or abolished late stent thrombosis, improved lesion imaging with computed tomography or magnetic resonance, facilitation of repeat treatments (surgical or percutaneous) to the same site, restoration of vasomotion, and freedom from side-branch obstruction by struts and from strut fracture-induced restenosis. Bioabsorbable stents have a potential pediatric role because they allow vessel growth and do not need eventual surgical removal.2 The progression of stenosis seen within stents 7 to 10 years after stenting has been attributed, at least in part, to inflammation around metallic struts, which might argue for an absorbable stent.3 Progression is also observed late after balloon angioplasty.4 Some patients say they prefer an effective temporary implant rather than a permanent prosthesis. Although the concept of bioabsorbable stents has created interest for >20 years, there are challenges in making a stent that has sufficient radial strength for an appropriate duration, that does not have unduly thick struts, that can be a drug delivery vehicle, and where degradation does not generate an unacceptable inflammatory response.5,6 We will review the different bioabsorbable stents that have been studied clinically and discuss the duration of the need …

The outcomes of operations for 539 patients with Ebstein anomaly

Our objective was to review the long-term outcomes of patients with Ebstein anomaly who underwent cardiac surgery at our institution. Patient records were reviewed, and all patients were mailed a medical questionnaire or contacted by means of telephone. Patients who had pulmonary atresia with an intact ventricular septum, complex conotruncal abnormalities, and atrioventricular discordance with ventriculoarterial discordance were excluded. From April 1, 1972, to January 1, 2006, 539 patients with Ebstein anomaly had 604 cardiac operations. The mean age at the time of the initial operation at our institution was 24 years (range, 8 days-79 years). Three hundred seventeen of the patients were female. One hundred forty-three (26.5%) patients had a prior invasive cardiac procedure before coming to Mayo Clinic. At the time of the first operation at Mayo Clinic, 182 patients had tricuspid valve repair, and 337 had tricuspid valve replacement. The 30-day mortality was 5.9% for the entire cohort (2.7% after 2001). Late survival was 84.7% at 10 years and 71.2% at 20 years. In a multivariate analysis of overall mortality for the patients' first operation at Mayo Clinic, increased hematocrit values, pulmonary valve stenosis, tricuspid valve replacement, absence of ablation of an accessory pathway, miscellaneous arrhythmia procedure, branch pulmonary artery enlargement, need for mechanical support postoperatively, emergency chest opening in the intensive care unit, and absence of sinus rhythm at dismissal were all predictive of mortality. When only preoperative characteristics were included, increased hematocrit values, mitral valve regurgitation requiring surgical intervention, prior cardiac procedure, and moderate-to-severe to severe reduction in right ventricular systolic function were associated with mortality. Preoperative sinus rhythm and an accessory pathway were associated with survival. Patients rated their health as excellent or good (New York Heart Association class I or II) in 83% of surveys returned. Ebstein anomaly can be surgically treated with low perioperative mortality. Both tricuspid valve repair and tricuspid valve replacement are associated with good long-term survival. Risk factors for poorer outcome included right, and/or left ventricular systolic dysfunction; increased hemoglobin/hematocrit values; male sex; right ventricular outflow tract obstruction; or hypoplastic pulmonary arteries.

Medication Dosing and Renal Insufficiency in a Pediatric Cardiac Intensive Care Unit: Impact of Pharmacist Consultation

Pediatric patients who have undergone cardiac surgery are at risk for renal insufficiency. The impact of pharmacist consultation in the pediatric cardiac intensive care unit (ICU) has yet to be defined. Patients admitted to the pediatric cardiac ICU at our institution from January through March of 2006 were included. Patient information, collected retrospectively, included: demographics, cardiac lesion/surgery, height, weight, need for peritoneal or hemodialysis, need for mechanical support, highest and lowest serum creatinine, ICU length of stay (LOS), renally eliminated medications, pharmacist recommendations (accepted or not), and appropriateness of dosing changes.There were 140 total admissions (131 patients; age: 3.0 +/- 6.3 years) during the study period. In total, 14 classes of renally eliminated medications were administered, with 32.6 +/- 56.4 doses administered per patient admission. Thirty-seven patient admissions had one or more medications adjusted for renal insufficiency; the most commonly adjusted medication was ranitidine. Patients who required medication adjustment for renal dysfunction were significantly younger compared to those patients not requiring medication adjustment. Pharmacist recommendations were responsible for 96% of medication adjustments for renal dysfunction, and the recommendations were accepted and appropriate all of the time. The monetary impact of pharmacist interventions, in doses saved, was approximately $12,000. Pharmacist consultation can result in improved dosing of medications and cost savings. The youngest patients are most at risk for inappropriate dosing.

The Prognostic Importance of Trauma Scoring Systems for Blunt Thoracic Trauma

Early identification and aggressive management of blunt thoracic trauma are essential to reduce the significant rates of morbidity and mortality. The aim of this study was to evaluate the independent predictive value of 5 different trauma scoring systems (Revised Trauma Score [RTS], Trauma and Injury Severity Score [TRISS], Injury Severity Score [ISS], Lung Injury Scale [LIS], and Chest Wall Injury Scale [CWIS]) with respect to prognostic factors such as tube thoracostomy duration, the need for mechanical support and thoracotomy, the length of hospital and ICU stay, morbid conditions, and deaths of patients with blunt thoracic trauma. The records of 152 patients with blunt thoracic trauma were reviewed and data consisting of the patients' age and gender, blood pressure and respiratory rate on admission, the extent of chest wall and intrathoracic injury, types of associated injuries, Glasgow Coma Scale (GCS) scores, the need for mechanical support and thoracotomy, tube thoracostomy duration, length of hospital and ICU stay, morbid conditions, and deaths were collected. The relations between the trauma scoring systems and prognostic factors were evaluated by multivariate analysis. The analysis showed that only TRISS was an independent predictor of mortality and only LIS was an independent predictor of morbidity, the need for thoracotomy, and tube thoracostomy duration. TRISS and LIS were independent predictors of the length of ICU stay. ISS, CWIS, and LIS were independent predictors of the need for mechanical support. RTS, TRISS, ISS and LIS were independent predictors of the length of hospital stay. The LIS grade appeared to correlate with the severity of blunt thoracic injury and was found to be the most useful scoring system in predicting the outcomes of these patients.

Prolonged cardiac allograft ischemic time – no impact on long‐term survival but at what cost?

The aim of this paper was to review the outcomes of cardiac transplantation with regards to short- and long-term survival, focusing particularly on patients who receive organs with long ischemic times and the resource utilization necessary to support such patients through their postoperative period. A retrospective review of 420 consecutive cardiac transplants in a single institution was undertaken. The five- and 10-yr survival rates for the entire group were 0.76 (95% CI: 0.72-0.80) and 0.60 (0.54-0.66). There was no decrease in mid- or long-term survival in patients who received organs with ischemic times over 300 min. Longer donor organ ischemic time was not associated with increased 30 d mortality but was significantly associated with longer intensive care bed stay, increased incidence of primary graft failure, need for mechanical support, and complications such as acute renal failures. Although using donor organs with longer ischemic times for cardiac transplantation does not impact on survival, there is a significantly increased utilization of resources to ensure these patients survive the postoperative period.

Management of 150 flail chest injuries: analysis of risk factors affecting outcome.

Flail chest continues to be an important injury with significant complications. The records of 150 patients presenting with flail chest injury were reviewed to determine risk factors affecting morbidity and mortality. During a 7-year period 150 patients with a flail chest injury were admitted to our trauma center. There were 111 men (74%) and 39 women (26%) ranging in age from 18 to 88 years with a mean age of 56.9. Only 66 (44%) had an isolated flail chest injury on admission. The majority of patients were older than 55 years (n = 89, 59.3%), 80 (53.3%) presented with an hemo-, or/and pneumothorax, 36 (24%) sustained a head injury and 25 (16.7%) needed ICU monitoring. The mean ISS score was 38. Age, concomitant diseases, presence of pneumothorax and/or hemothorax, Severity Score (ISS), the need for mechanical support, length of stay and deaths were evaluated by using the t-test and chi2 test where appropriate. Sixty-seven patients (44.6%) were conservatively treated, while 80 (53.3%) needed thoracic drainage. Only in 6 cases (4%) thoracotomy was required, while in 9 (6%) laparotomy was performed. Mortality rate reached 5.3%. The main factors correlated with an adverse outcome were: ISS and the presence of associated injuries, while age, hemopneumothorax and mechanical support affected the length of hospitalization but not the mortality. (1) Age and hemopneumothorax did not affect mortality. (2) ISS was found to a strong predictor on outcome concerning morbidity and prolonged hospitalization but did not influence mortality rate. (3) Mechanical support was not considered a necessity for the treatment of flail chest.

Risk factors for primary graft failure after pediatric cardiac transplantation: importance of recipient and donor characteristics

Background Primary graft failure, or circulatory insufficiency immediately after transplantation, frequently occurs after pediatric cardiac transplantation and is the most common cause of death after infant transplantation. Risk factors for pediatric primary graft failure are poorly defined. Methods We retrospectively reviewed donor, procedural and recipient characteristics for primary graft failure in 165 pediatric cardiac transplant recipients (median age at transplant 1.1 years) by multivariatle logistic regression. Primary graft failure was defined as the need for mechanical circulatory support or use of multiple intravenous inotrope/pressors, including epinephrine, for circulatory support within the first 24 hours after transplantation. Results Primary graft failure occurred in 54 patients (33%); 24 patients (15%) required mechanical support for their graft failure; and primary graft failure was the cause of death or graft loss in 10 patients. Recipient risk factors associated with an increased risk of primary graft failure included diagnosis of congenital heart disease and a need for mechanical support before transplantation. Ventilator support before transplantation and maximal pulmonary vascular resistance index were risk factors for the development of isolated right ventricular graft failure. Donor risk factors associated with an increased risk for primary graft failure included increasing donor recipient weight and body surface area ratios; increasing donor ischemic time; anoxia as a cause of death; and increasing cardiopulmonary resuscitation time. Donor blood type O + and hyperdynamic donor systolic function were associated with a decreased risk of primary graft failure. Conclusions Multiple donor, recipient and procedural risk factors, including the type and severity of heart disease in the recipient before transplantation, are associated with primary graft failure after pediatric cardiac transplantation. Avoidance of matching high-risk donors to high-risk recipients may improve morbidity and mortality after transplantation.

Evolution of extreme xeromorphic characters in wood: a study of nine evolutionary lines in Cactaceae

Vessels of xeric‐adapted woods have been predicted to be narrower than those of mesic‐adapted woods, to occur at higher densities, to occur in larger clusters, and to have a greater percentage of them in clusters. These predictions were tested by comparing wood structure of several evolutionary lines of xeric‐adapted cacti to that of mesic‐adapted Pereskia, which probably resembles the ancestral cacti. Although derived cacti occur in habitats with water stress ranging from mild (rain forests) to severe (open deserts with little vegetation other than cacti), as long as plants retain wood with an ordinary fibrous matrix, wood characters are remarkably uniform and not correlated with habitat aridity. However, in several evolutionary lines, novel wood types occur with characters that fulfill the predictions for xeric‐adapted woods listed above. However, conductive area (fraction of wood transverse‐sectional area occupied by conduits) and estimated specific conductance (conductance per square millimetre) are correlated with shoot height (the need for mechanical support from xylary fibers) rather than with habitat aridity: tall plants transport water through relatively few, wide vessels, permitting much of the wood volume to consist of fibers. Small plants with little wood use large numbers of narrow vessels rather than small numbers of wide ones, thereby achieving conductive safety.

Intermittent antegrade warm blood cardioplegia in aortic valve replacement.

Intermittent antegrade warm blood cardioplegia (IAWBC) is a well established technique of myocardial protection for coronary artery surgery, with metabolic and experimental basis. To evaluate its effectiveness in aortic valve replacement (AVR), we compared 171 consecutive patients who underwent first AVR using IAWBC (group A) with the last 100 consecutive patients who underwent first AVR using intermittent antegrade cold blood cardioplegia (IACBC) (group B). The endpoints considered were myocardial protection related (recovery of spontaneous rhythm, need for mechanical support, incidence of low-output syndrome, perioperative Q wave myocardial infarct, CK-MB levels, ventricular arryhthmias and lidocaine infusion requirement, cardiac-related deaths, and deaths any cause) and temperature perfusion related (bleeding, awaking time, time to extubation, and cerebrovascular accidents). Mortality was similar in both groups, but no patient in group A died for cardiac-related cause (0 vs 4, p < 0.01). More patients in group A recovered a spontaneous rhythm (144 vs 47, p < 0.0001). Incidence of low-output syndrome was higher in group B (16 vs 3, p < 0.0005), as well as ventricular arryhthmias incidence and need for lidocaine infusion (respectively 15 vs 2, p < 0.0001, and 10 vs 1, p < 0.0005). Awaking time was shorter in warm patients (2.5 +/- 2.5 hours vs 4.4 +/- 3.7 hours, p < 0.0005), as the extubation time (9.4 +/- 7.7 hours vs 13.5 +/- 11.7 hours, p < 0.0005) and bleeding (803 +/- 714 mL/24 hours vs 1051 +/- 1375 mL/24 hours, p < 0.05). As a consequence, the intensive care unit and the postoperative hospital stays were shorter in group A (32 +/- 27 hours vs 48 +/- 20 hours, p < 0.0005, and 7.2 +/- 3.1 days vs 11.3 +/- 5.4 days, p < 0.0001, respectively). IAWBC provides lower cardiac-related mortality and morbidity in patients who undergo AVR in comparison with IACBC.

Invasive testing in congestive heart failure.

Preview Cardiac catheterization of patients with congestive heart failure (CHF) can provide information that may indicate the cause of the CHF, suggest its prognosis, or serve as a basis for treatment decisions. Under what circumstances do CHF patients require hemodynamic assessment? What are the benefits of contrast angiography and coronary arteriography? Why is it important to consider endomyocardial biopsy in any patient with CHF who does not have significant coronary or valvular disease? Dr Murali addresses these and other questions.

Timing for Implantation and Transplantation in Mechanical Bridge to Transplantation

The implantation of a mechanical blood pump in a deteriorating candidate for heart transplantation is indicated in general if the cardiac index is less than 1.9 L/min/m2 despite maximal inotropic support. Deterioration of end organ function may be taken as a second factor indicating the need for mechanical support as patients with acute onset of shock may react differently from patients with chronic deterioration. Preoperative need for dialysis largely reduces the chances of long-term survival. The time on support should be long enough to normalize or at least improve secondarily damaged organ systems, but with time infectious and thromboembolic complications will increase. So optimal periods for artificial heart support range between two days and four weeks. Age less than 40 years is a positive predictor for outcome in TAH bridging. The general guidelines, however, do not preclude a favourable outcome in complicated cases, as we show in our own series.

4967262 Gull-wing zig-zag inline lead package having end-of-package anchoring pins

A semiconductor package having a gull-wing, zig-zag, inline-lead configuration and end-of-package anchoring devices for rigidly af fixing the package to a circuit board such that each lead is in compressive contact with its associated mounting pad on the board. The anchoring devices of a first embodiment comprise anchoring pins (12) having fish-hook-type barbs (20) which lock against the under side of the board (13) when the pins are inserted through holes (15) in the board; a second embodiment utilizes anchoring pins (54) which are adhesively bonded in recesses (52) that have been drilled or molded into the board (52); a third embodiment utilizes anchoring pins (62), the ends of which can be bonded directly to planar peg-bonding regions on the surface of the board (63); and a fourth utilizes tapered anchoring pin (74) which may be inserted with an interference fit into holes (75) in the board. The invention eliminates the need for mechanical support of the packages during solder reflow operations used during board assembly and repair.

Theoretical study of variables affecting the export of assimilates from branches of Picea.

A theoretical analysis was done to identify the features of conifer branch development, based on a model for Picea sitchensis (Bong.) Carr., that affect the ability to export assimilates, assuming (i) a branch's requirement for assimilates is determined by its need for mechanical support, and (ii) the production of assimilates is a simple function of total shoot length. There were three salient findings. First, there is an optimum and maximum shoot length for assimilate export by unbranched shoots. Second, the less a shoot extends itself each year, the more assimilate it may export, all else being equal. Third, there is a larger surplus of assimilates for export when a shoot develops laterals. A combination of lateral branching, deflection and decreased elongation can enable branches to continue growing and exporting assimilates for many years, as occurs at the bases of tree crowns.

A Rapid Method for Determining the Need for Mechanical Support of the Right Ventricle

Right ventricular failure following cardiac surgery must be rapidly diagnosed and treated to minimize injury to the heart. Switching from aortic to pulmonary artery perfusion during cardiopulmonary bypass is a method of rapidly testing the adequacy of right ventricular function and supporting the ventricle if necessary. A centrifugal pump has been used for long-term support for two cases managed in this manner.

Liana Phenology on Barro Colorado Island, Panama

The production of leaves, flowers, and fruits by 68 lianas (woody vines) representing 43 species was studied on Barro Colorado Island, Panama, over a period of 12 months. The liana phenology data are contrasted with data for 16 species of light-demanding (pioneer) trees and 10 species of shade-tolerant trees. More of the lianas were evergreen and produced new leaves during more of the year than the trees. Flowering of lianas was concentrated during the middle of the dry season and the middle of the wet season. Many liana species, especially those with wind-dispersed propagules, fruited late in the dry season; several fleshy fruited species underwent a secondary fruiting peak late in the wet season. LIANAS ARE WOODY CLIMBING PLANTS that can grow taller only with mechanical support. Ramifications of this basic difference between lianas and trees are found in several aspects of liana biology. In this paper we explore the relationship between the climbing habit and the temporal distribution of leaf, flower, and fruit production in woody vines. We describe the phenological behaviors of lianas on Barro Colorado Island, try to relate the timing of leaf production and shedding with the hydraulic architecture of their xylem, and compare liana phenology with that of trees in the same forest. Although the climbing habit evolved independently in several different phylogenetic lineages (Schenck 1892), several anatomical and ecological characteristics generally accompany the need for mechanical support. For example, resources that trees must invest in support tissue are allocated by lianas to growth in length (Darwin 1867), and lianas generally have extremely rapid extension growth (Putz 1984). In addition to a significant lack of structural materials, lianas can be small in diameter for the leaf areas they supply with water and nutrients because they have large and efficient xylem vessels (Putz 1983). Large-diameter vessels are advantageous when water is available, but during periods of water stress, they are particularly prone to cavitation (Zimmermann & Brown 1971). The likelihood of embolism formation is increased when stems containing water columns under tension are jostled, something that must frequently happen to lianas hanging down from the treetops. These factors lead us to expect that, to maintain high water potential during dry periods and thus lower the risk of vessel cavitation, lianas should be deciduous during the dry season and not commence leaf production until the beginning of the rainy season. Several phenological studies have included lianas, two of which were conducted on Barro Colorado Island (Croat 1969, Foster 1982). By tabulating the dates on which fertile herbarium collections were made and making field observations, Croat (1969) determined that the majority of liana species flower earlier in the dry season than most trees. Both Croat (1969) and Foster (1982) found that many liana species, particularly those with wind-dispersed seeds, bear ripe fruits toward the end of the dry season, presumably to take advantage of the trade winds and open canopy conditions that prevail at that time of year. STUDY SITE AND METHODS Barro Colorado Island (9?09'N, 795 1'W) is a 15.6-km2 island with semideciduous forest classified as tropical moist

Factors Influencing Early and Late Survival in Patients with Combined Mitral Valve Replacement and Myocardial Revascularization and in Those with Isolated Replacement

During a 5 1/2-year period, 251 patients underwent mitral valve replacement (MVR) at our institution: 76 had combined MVR and coronary artery bypass grafting (CABG), and 175 without major coronary artery disease (CAD) had isolated MVR. In-hospital mortality for MVR + CABG was 13.2% (10/76); it was 8.6% (6/70) when patients with preoperative mechanical support were excluded, 7.9% (5/63) for elective operations, and 8.2% (5/61) for nonischemic mitral disease. Overall, in-hospital mortality for isolated MVR was 6.3% (11/175); it was 4.4% (7/161) excluding patients requiring mechanical support and 3.1% (5/157) for elective operations. Of a host of clinical characteristics in patients with MVR + CABG, few were found to influence in-hospital mortality: age greater than 60 years, degree of incapacitation (New York Heart Association Functional Class IV), previous history of myocardial infarction or congestive heart failure, cardiac enlargement (cardiothoracic index greater than 50%), and ischemic mitral disease (33.3% in-hospital mortality; p < 0.05). Of the invasive variables, only one influenced in-hospital mortality: wall motion score greater than 10 (31.6% in-hospital mortality; p < 0.01). Of the operative variables studied, the number of grafts (3 or more: 33.3% in-hospital mortality; p < 0.05), the need for mechanical support (47.4% in-hospital mortality; p < 0.0001), and emergency operation (38.5% in-hospital mortality; p < 0.005) had a significant effect on mortality. The type of mitral lesion, the type of prosthesis, the extent of CAD or the completeness of revascularization, the presence of pulmonary hypertension, and atrial fibrillation appeared to have no influence. Survival at 6 years was 83 ± 5% for patients having MVR + CABG and 89 ± 2% for those having isolated MVR ( p < 0.03). Of the following variables—ejection fraction, extent of CAD, completeness of revascularization, etiology of lesion, and wall motion score—only the last strongly influenced late survival in patients with MVR + CABG. In summary, in-hospital mortality is higher among patients having MVR + CABG, especially if urgent operation or mechanical support is needed and multiple bypass grafts are performed. Age and cardiac enlargement also play a role. Once CAD is corrected, that is, when most— but not necessarily all—diseased arteries are bypassed, overall survival does not differ from that of patients with isolated MVR and no major CAD. The single most important variable for early and late survival in MVR + CABG appears to be wall motion score at cineventriculography.