PubMed Health⌕ Search

Biomedical subjects

A Chaux

Publications and source records attributed to A Chaux.

At least 19 recordsLinked to original sources
PubMed2001

Twenty-year comparison of tissue and mechanical valve replacement.

OBJECTIVE: We sought to compare outcomes with tissue and St Jude Medical mechanical valves over a 20-year period. METHODS: Valve-related events and overall survival were analyzed in 2533 patients 18 years of age or older undergoing initial aortic, mitral, or combined aortic and mitral (double) valve replacement with a tissue valve (Hancock, Carpentier-Edwards porcine, or Carpentier-Edwards pericardial) or a St Jude Medical mechanical valve. Total follow-up was 13,390 patient-years. There were 666 St Jude Medical aortic valve replacements, 723 tissue aortic valve replacements, 513 St Jude Medical mitral valve replacements, 402 tissue mitral valve replacements, 161 St Jude Medical double valve replacements, and 68 tissue double valve replacements. The mean age was 68 +/- 13.3 years (St Jude Medical valve, 64.5 +/- 12.9; tissue valve, 72.0 +/- 12.6). RESULTS: There were no overall differences in survival between tissue and mechanical valves. Multivariable analysis indicated that the type of valve did not affect survival. Analysis by age less than 65 years or 65 years or older and presence or absence of coronary disease revealed similar long-term survival in all subgroups. The risk of hemorrhage was lower in patients receiving tissue aortic valve replacements but was not significantly different in patients receiving mitral valve or double valve replacements. Thromboembolism rates were similar for tissue and mechanical valve recipients. However, reoperation rates were significantly higher in patients receiving both aortic and mitral tissue valves. The reoperation hazard increased progressively with time both in patients receiving aortic and in those receiving mitral tissue valves. Overall valve complications were initially higher with mechanical aortic valves but not with mechanical mitral valves. However, valve complication rates later crossed over, with higher rates in tissue valve recipients after 7 years in patients undergoing mitral valve replacement and 10 years in those undergoing aortic valve replacement. CONCLUSIONS: Tissue and mechanical valve recipients have similar survival over 20 years of follow-up. The primary tradeoff is an increased risk of hemorrhage in patients receiving mechanical aortic valve replacements and an increased risk of late reoperation in all patients receiving tissue valve replacements. The risk of tissue valve reoperation increases progressively with time.

Adult↗
PubMed1999

Cardiac reoperations in octogenarians: analysis of outcomes.

BACKGROUND: With the rapid growth of the elderly segment of the population, more octogenarians are referred for complex cardiac interventions, including reoperations. Data regarding the outcomes, quality of life, and long-term results after reoperative open-heart surgical procedures in octogenarians are scarce. METHODS: We retrospectively studied 113 consecutive octogenarians (mean age, 83+/-2.6 years) who underwent reoperative cardiac procedures within a 13-year period. Coronary artery bypass grafting (CABG) was performed in 49 patients (CABG group), valvular procedures (aortic, mitral, or tricuspid valve, alone or in combination) in 35 (valve group), and combined CABG and valve intervention in 29 (combined CABG and valve group). RESULTS: The 30-day mortality rate was 8% (4 of 49) for the CABG group, 9% (3 of 35) for the valve group, and 17% (5 of 29) for the combined CABG and valve group. One- and 5-year actuarial survival rates were, respectively, 85%+/-5% and 58%+/-10% for the CABG group, 78%+/-7% and 53%+/-12% for the valve group, and 69%+/-9% and 63%+/-10% for the combined CABG and valve group. Sixty-one percent of patients in the CABG group, 40% in the valve group, and 38% in the combined CABG and valve group were in New York Heart Association class I or II postoperatively at a mean follow-up time of 2.1+/-2.4 years. Similarly, 91%, 85%, and 80%, respectively, thought that they had an improved quality of life and were satisfied with their functional status. CONCLUSIONS: Cardiac reoperations can be performed successfully in most octogenarians, although with an increased risk, particularly in the combined CABG and valve group. Long-term survival is acceptable with improved quality of life and functional status. However, it is possible that these results could be improved in this high-risk group of patients with earlier referral and surgical intervention, for the effective use of health care resources.

Aged↗
PubMed1998

A 20-year experience with the Hancock porcine xenograft in the elderly.

BACKGROUND: The availability of 20 years of follow-up data on the Hancock porcine valve (Medtronic Inc, Irvine, CA) allows determination of long-term actual and actuarial failure rates in the elderly. METHODS: We analyzed outcomes after mitral or aortic valve replacement with the Hancock porcine valve in 491 consecutive patients, comparing actual and actuarial valve failure rates in the elderly (age 65 or older) with those in younger patients. RESULTS: The average age of aortic valve replacement recipients was 68+/-14 years (N = 243) and of mitral valve replacement recipients, 64+/-12 years (N = 248). Average follow-up was 7.0 years (1,673 patient-years) for aortic valve replacement and 7.3 years (1,781 patient years) for mitral valve replacement recipients. The median time to reoperation or structural failure was 15.9 years for aortic valve replacement patients and 14.3 years for mitral valve replacement patients. However, few elderly patients survived to 15 years (22% of the elderly aortic valve replacement and 13% of the older mitral valve replacement patients). The 15-year actual reoperation rate was therefore only 10% in the elderly aortic valve replacement compared to 30% in the younger aortic valve replacement patients. For mitral valve replacement, the 15-year actual reoperation rate was 11% in the elderly and 36% in the younger patients. The lifetime reoperation risk (the maximum potential number of patients who might ever undergo reoperation during their lifetime) is the sum of actual survival and actual reoperation rates. The lifetime reoperation risk was 20% or less for elderly aortic valve replacement patients and 18% or less for elderly mitral valve replacement patients. CONCLUSION: These data suggest that about 1 in 10 elderly patients (65 years or older) receiving a Hancock valve will require reoperation within 15 years and less than one in five will ever require reoperation in their lifetimes.

Actuarial Analysis↗
PubMed1998

Perivascular delivery of a nitric oxide donor inhibits neointimal hyperplasia in vein grafts implanted in the arterial circulation.

OBJECTIVE: Nitric oxide has been reported to reduce intimal hyperplasia as a response to arterial injury. This study was designed to assess the possible effect of perivascular application of a nitric oxide donor on neointimal proliferation occurring in veins exposed to the dynamics of the arterial circulation in a hypercholesterolemic rabbit model. METHODS: Autologous jugular vein grafts were implanted in the carotid circulation of 20 hypercholesterolemic rabbits. A mixture of a biodegradable polymer and the nitric oxide donor, spermine/nitric oxide, which releases nitric oxide with a half-life of 39 minutes, was applied periadventitially at the time of implantation. Controls were veins bathed in saline solution, polymer alone, and polymer plus the carrier vehicle spermine without nitric oxide. Animals (n = 5 in each group) were put to death on day 28 for morphometric analysis, cell count, and immunohistochemical staining. RESULTS: Treatment with perivascular nitric oxide donor significantly decreased wall thickness (126 +/- 24 microm vs 208 +/- 45 microm, p = 0.0017) and area (124 +/- 22 microm2/microm vs 211 +/- 37 microm2/microm, p = 0.005). With the carrier vehicle spermine alone, there was a trend toward reduced intimal thickness, but the change was not statistically significant. In the grafts treated with nitric oxide donor, expression of insulin-like growth factor, fibroblast growth factor, thrombospondins, fibronectin, and tenascin was reduced. CONCLUSION: The periadventitial delivery of nitric oxide donor produces a reduction of neointimal hyperplasia in veins implanted in the arterial circulation. The mechanism of action is not entirely clear, but the reduction cannot be explained on the basis of decreased cell proliferation alone. Other possibilities are modulation of protein synthesis of vascular smooth muscle cells and production of extracellular matrix components.

Animals↗
PubMed1998

Postinfarction ventricular septal defect.

Despite improved screening and diagnostic capabilities for the presence of coronary artery disease (CAD), with the promise of improved outcomes from earlier therapeutic interventions, postinfarction ventricular septal perforation (VSD) continues to be a very difficult therapeutic challenge. In our experience with VSD, the incidence of this complication per year has decreased, almost certainly related to earlier and more effective medical therapy in patients with CAD. By contrast, the outcomes of surgical repair have not improved, even with an aggressive strategy about bypassing involved coronary arteries. Furthermore, the earliest possible surgical approach and the incorporation of a number of technical advances, especially those relating to myocardial preservation, have not had an apparent effect. Because the number of patients who underwent operation is small, it is not possible from our single-institutional experience to define statistical significance to our continuing observations of this condition, suggesting that the clinical spectrum of postinfarction VSD is still evolving. Important changes appear to be associated with an increase in the number of female patients observed (60%), in contrast to their lesser frequency of uncomplicated coronary bypass (18%) and a change in the anatomic substrate, with posterior infarctions and rupture now accounting for 73% of cases at Cedars-Sinai. For the present, earliest possible surgical intervention to minimize the severity of multi-organ failure and use all of the advanced therapeutic modalities of cardiac support and surgical therapy that are available continues to be indicated. For the long term, continuing advances in the earlier diagnosis and more aggressive management of CAD, especially in females, may hold the best promise for a continued decrease in the occurrence of this very difficult-to-treat postinfarction complication.

Aged↗
PubMed1997

Cardiac operations in patients 90 years of age and older.

BACKGROUND: Growth of the elderly population worldwide, and specifically in the United States, will continue to accelerate and will have a profound impact on the cost and delivery of health care resources in the future. A medical strategy that allows the elderly to live independently is essential to most cost-effective use of our resources. The question remains as to what will be the future of surgical therapy for this increasing population. METHODS: We retrospectively studied the cases of 30 consecutive nonagenarians (mean age, 92.3 +/- 1.8 years) who underwent a cardiac operation within a 9-year period. All patients were in New York Heart Association class III or IV and underwent operation urgently or emergently. RESULTS: The 30-day mortality rate was 10%, and the actuarial survival rates were 81% +/- 8% and 75% +/- 9% at 1 year and 2 years, respectively. Seventy-eight percent of survivors were in New York Heart Association class I or II within 2 years after operation and had an improved quality of life. The cost of providing care in this age group was 24% higher than in octogenarians. CONCLUSIONS: Advanced age in and of itself (>90 years) should not be a contraindication to an open-heart operation, although morbidity, mortality, and cost may be higher. However, selective criteria identifying risks and benefits for individual patients should be applied. The aging of our population will have a profound impact on the cost and delivery of health care resources in the future. This issue must be addressed in the current debate on the provision of expensive procedures under a realigned national health-care system.

Actuarial Analysis↗
PubMed1996

Flow measurements in an aortocoronary bypass graft casting.

Flow visualization and pressure measurements were carried out in a singel valve saphenous vein casting which was made from a saphenous vein segment obtained from a bypass patient at Cedars Sinai Medical Center. Dye was injected to understand the flow around the valve. The dye showed very complex flow patterns around the valve and in the valve sinus, and the cavity formed by a ligated branch. For steady flow, pressure drops across the valve were 0.72, 2.0 and 6.3 mmHg for the physiological flow rates of 45, 84, and 169 ml/min, respectively. Overall pressure drop across the casting (compared to Poiseuille flow for a straight tube) increased with the flow rate, being 130 to 290 percent higher over this flow rate range. In the case of pulsatile flow, pressure drops across the valve were 0.95 and 3.0 mmHg for the flow rates of 47 and 87 ml/min which were 26 and 43 percent higher than those of steady flow. Overall pressure drop was 220 and 360 percent higher for those flow rates compared to Poiseuille flow. The measured spatial pressure distributions along the casting and flow visualization indicated the global nature of the flow field with the accelerated flow through the valve separating and reattaching downstream along the wall in the pressure recovery region. Atherosclerosis may be prone to occur in the lower shear region along the wall beyond the valve tip in the reattachment region, as we have observed in vivo in rabbit experiments.

Biomechanical Phenomena↗
PubMed1996

Revascularization alone or combined with suture annuloplasty for ischemic mitral regurgitation. Evaluation by color Doppler echocardiography.

To determine the effectiveness of revascularization alone or combined with mitral valve repair for ischemic mitral regurgitation, we performed color Doppler echocardiography intraoperatively before and after cardiopulmonary bypass in 49 patients (mean age, 70 +/- 9 years) with concomitant mitral regurgitation and coronary artery disease (triple vessel or left main in 88%; prior infarction in 90%). After revascularization alone (n = 25), the mitral annulus diameter (2.88 +/- 0.44 cm vs 2.88 +/- 0.44 cm), leaflet-to-annulus ratio (1.44 +/- 0.30 vs 1.44 +/- 0.29), and mitral regurgitation grade (1.7 +/- 0.9 vs 1.8 +/- 0.7) remained unchanged (p = NS, postpump vs prepump); mitral regurgitation decreased by 2 grades in only 1 patient (4%). After combined revascularization and mitral valve suture annuloplasty (Kay-Zubiate; n = 24), the annulus diameter decreased (to 2.57 +/- 0.45 cm from 3.11 +/- 0.43 cm), the leaflet-to-annulus ratio increased (to 1.46 +/- 0.25 from 1.20 +/- 0.21), and the mitral regurgitation grade decreased significantly (to 0.9 +/- 0.9 from 2.8 +/- 1.0) (p < 0.01); mitral regurgitation decreased by 2 grades or more (successful repair) in 75%. The origin of the jet correlated with the site of prior infarction (p < 0.05), being inferior in cases of posterior or inferior infarction (67%), and central or broad in cases of combined anterior and inferior infarction (70%). Despite a slightly higher 30-day mortality in the repair group (p = 0.10), there was no significant difference in survival between the 2 surgical groups at 5 years or 8 years. Therefore, in this study of patients with mitral regurgitation and coronary artery disease, reduction in regurgitation grade with revascularization alone was infrequent. Concomitant suture annuloplasty significantly reduced regurgitation by reestablishing a more normal relationship between the leaflet and annulus sizes. The failure rate after suture annuloplasty was 25%; alternative repair techniques such as ring annuloplasty may have a lower failure rate.

Aged↗
PubMed1995

Absence of lethal reperfusion injury after 3 hours of reperfusion. A study in a single-canine-heart model of ischemia-reperfusion.

BACKGROUND: Whether reperfusion can cause necrosis of previously viable myocytes (lethal reperfusion injury) remains controversial. Numerous studies examined the ability of various agents to prevent or limit reperfusion injury, but the results were contradictory. In a single-canine-heart model of ischemia-reperfusion, we previously demonstrated that 5 minutes of reperfusion does not increase the transmural extent of necrosis. Since the 5-minute period of reperfusion is considered by some to be too short for the full manifestation of reperfusion injury, we reexamined the issue of lethal reperfusion injury using a modification of the single-heart model of ischemia-reperfusion that allowed extending the reperfusion period to 3 hours. METHODS AND RESULTS: In anesthetized, open-chest dogs, the distal half of the left anterior descending coronary artery (LAD) segment between the last diagonal branch and the apex was perfused via a shunt from the left carotid artery. The shunt was closed for periods of 90 to 180 minutes, depending on the ECG severity of ischemia, and reperfused for 3 hours. While the distal region was perfused from the carotid artery, the LAD was occluded proximal to the last diagonal branch for the same period of time as the distal region had been earlier. The time of occlusion was chosen such that the end of the occlusion period coincided with the end of the experiment. Thus, both regions of the LAD territory were subjected to identical periods of ischemia, but only the distal region was reperfused. At the end of the experiment, the boundary between the proximal (nonreperfused) and distal (reperfused) area was delineated by blue dye, and the heart was arrested, cut into slices 1 cm thick parallel to the LAD, and placed in triphenyltetrazolium chloride. The epicardial edges of necrosis in the reperfused and the nonreperfused regions were examined for any shift that might suggest a difference in the transmurality of necrosis. The areas of necrotic and viable myocardium were measured by planimetry within 1 cm on either side of the boundary. In all 14 dogs, the epicardial edges of necrosis ran as a single line across the boundary, and no shift was present. There was also no difference in the transmurality of necrosis between the reperfused and nonreperfused regions (64.9 +/- 20.7% versus 66.1 +/- 17.0% of left ventricular wall thickness, respectively, P = .32 by paired t test). CONCLUSIONS: In a single-canine-heart model of ischemia-reperfusion, there was no evidence of lethal reperfusion injury after 3 hours of reperfusion.

Animals↗
PubMed1995

A cardiothoracic surgery information system for the next century: implications for managed care.

The United States health care system is under tremendous pressure to cut costs while maintaining quality. One mechanism to reduce costs is managed care--a system with both risks and benefits for patients, providers, and payors, and one that requires large volumes of data to ensure optimal medical and financial decision-making. In this review, we describe the types of information needed by managed care systems, including medical outcome data (satisfaction, survival, quality of life, and complications) and financial data (costs and long-term resource utilization). From a provider's point of view, the customers for these data range from individual patients to large self-insured corporations, and we describe the data required for each potential customer. Finally, as a concrete example of how data can be collected and analyzed to improve a provider's competitiveness, we describe the Cedars-Sinai Medical Center cardiothoracic surgery database from a managed care perspective. The concepts presented are generalizable to other subspecialties, and will become more important in the increasingly competitive milieu of American health care.

Cardiac Surgical Procedures↗
PubMed1995

Influence of vein valves in the development of arteriosclerosis in venoarterial grafts in the rabbit.

Coronary saphenous vein grafts in human beings have a more limited long-term patency rate than internal thoracic artery grafts, primarily because of more rapid development of arteriosclerosis. The factors responsible for this increased susceptibility are not completely understood. To test the hypothesis that vein valves may influence this process, we studied 48 hypercholesterolemic rabbits with jugular vein grafts interposed into the carotid arterial circulation. In 24 animals (group A), the vein segments did not contain a vein valve. In the other 24 animals (group B), a vein valve was present. Both groups were further divided in four subgroups of six to be put to death at 2, 4, 6, and 8 weeks after the operation. All animals were fed a 2% cholesterol diet. At postmortem examination, alternate 2 mm sections were either stained with hematoxylin and eosin for histologic and morphometric studies or frozen in liquid nitrogen for immunohistochemistry and in situ hybridization studies. Proliferating cell nuclear antigen immunostaining was used to study cell proliferation. Wall thickness of vein grafts increased with time. During the first 2 weeks intimal and medial thickening was primarily due to an increase in numbers of cells. Between 2 and 6 weeks further intimal and medial thickening occurred, but without additional increase in cell numbers. After 6 weeks, foam cells and lipid deposits started to appear. By 8 weeks, changes identical to those seen in arteriosclerotic plaques in human beings were evident. These changes developed sooner and with more intensity in group B animals (p < 0.01 to 0.001), and they developed faster and with more severity in segments of vein located distal to the valve than in the segments located proximal to the valve (p < 0.001). This is the first controlled experiment demonstrating that the presence of valves in the vein segments is associated with augmented and accelerated intimal changes leading to vein atheromatosis.

Animals↗
PubMed1994

Postinfarction ventricular septal defect in the elderly: analysis and results.

Fifteen elderly patients (age more than 70 years) underwent surgical repair of postinfarction ventricular septal defects during the years 1980 through 1992. The operative (to discharge or < 30 days) mortality rate was 47%, and the complication rate among survivors was 63%. The probability of survival at 1 year was 47% +/- 13%. Because of the small sample size of our patient population, predictive preoperative risk factors associated with early mortality could not be identified with certainty. However, there is a trend suggesting that high right atrial pressures (p = 0.15) and the need of an intraaortic balloon pump preoperatively (p = 0.12) influence 30-day mortality, as previously described in larger series. Of 5 long-term survivors, 3 are in New York Heart Association functional class I and 2 are in class II. Our experience in this group of patients suggests that in the elderly, a very aggressive approach should be taken in recommending early surgical intervention for postinfarction ventricular septal defect before hemodynamic deterioration ensues and severely compromises chances for survival.

Aged↗
PubMed1994

Ten-year experience of cardiac surgery in patients aged 80 years and over.

Five hundred twenty-eight consecutive patients aged 80 years and over (mean age, 83.1 +/- 2.7 years) underwent cardiac operations with hypothermia (mean, 21.9 degrees +/- 2.2 degrees C), hyperkalemic cardioplegia, and cardiopulmonary bypass in a 10-year period. Fifty-six percent of the patients were male. Preoperatively, 68% of the patients were in New York Heart Association functional class IV, and 31% were in class III. Among them, 303 patients had isolated coronary artery bypass grafting (CABG) (group I), 132 had aortic valve replacement only or combined with CABG (group II), 42 had mitral valve replacement only or combined with CABG (group III), 31 had mitral valve repair and CABG (group IV), and 20 had double-valve procedure only or combined with CABG (group V). The 30-day or in-hospital mortality was 8.3% in group I, 4.5% in group II, 29% in group III, 23% in group IV, and 30% in group V. Total 30-day or in-hospital mortality was 10.6%. One-year and 5-year actuarial survival rates were as follows: group I, 82% and 62%; group II, 85% and 58%; group III, 61% and 37%; group IV, 56% and 19%; and group V, 63% and 15%. Total 1-year and 5-year actuarial survival were 79% and 54%. At follow-up (mean, 2 years), 70% of overall survivors reported that their general health had improved. Our experience demonstrates that for select patients aged 80 years and over with unmanageable cardiac symptoms, CABG and aortic valve replacement groups had better results in improving quality of life as compared with patients having mitral or combined procedures.

Actuarial Analysis↗
PubMed1994

High-efficiency gene transfer to autologous rabbit jugular vein grafts using adenovirus-transferrin/polylysine-DNA complexes.

Within the first year, 15-20% of coronary artery saphenous bypass vein grafts (SVGs) occlude because of thrombosis or progressive intimal hyperplasia. One potential new strategy to reduce this complication would be to introduce antithrombotic or antiproliferative genes in vein grafts before implantation. The success of this approach requires an efficient DNA delivery system. In the present study we tested the feasibility of using adenovirus-transferrin/polylysine-DNA complexes (TfAdpl/DNA) to achieve high-efficiency gene transfer into vascular interposition vein grafts. All studies used the Escherichia coli LacZ (beta-galactosidase [beta-Gal]) reporter gene under the control of the cytomegalovirus (CMV) earlier promoter and enhancer (pCMV/LacZ). Autologous rabbit jugular vein segments were incubated ex vivo for 60 min in a solution of TfAdpl/DNA complexes (1.2 x 10(10) biotinylated adenovirus particles, 2,430 ng of streptavindylated polylysine. 10 micrograms of plasmid DNA, and 9 micrograms of transferrin-polylysine per ml), and then reimplanted across the ligated right carotid artery. Control veins were incubated in TfAdpl solution in which DNA was omitted. A total of six grafts were treated with TfAdpl/DNA, and two grafts were treated with TfAdpl. Veins were harvested 3 (n = 3) and 7 (n = 3) days later and beta-Gal activity was determined by X-Gal chromogen staining. All six TfAdpl/DNA-treated grafts stained intensely blue, whereas control grafts were negative. Microscopic examination of serial sections revealed intracellular blue granules consistent with beta-Gal activity to be present in all of the endothelial cells and in numerous medial and advential cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoviridae↗