摘要:

AbstractDisappointing long‐term results with saphenous vein graft (SVG) for coronary bypass and excellent long‐term results with internal mammary artery (IMA) to coronary bypass have prompted a search and research for other alternative coronary bypass conduits. Experience with the radial artery was disappointing due to early failure of those grafts. Likewise, conduits of artificial materials and homograft veins have not produced acceptable long‐term re

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00252.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPulmonary embolism infrequently results in severe chronic pulmonary arterial obstruction. However, when it does, affected patients are significantly symptomatic and have shortened survival. Medical management has proven ineffective. In the majority of surgical reports, unilateral thoracotomy with distal pulmonary arteriotomies has been emphasized. The average operative mortality was 22%. In this article, we discuss various preoperative considerations and describe in detail a surgical approach using median sternotomy for bilateral pulmonary thrombo‐endarterectomy with cardiopulmonary bypass, deep hypothermia and circulatory arrest. With this standardized approach in 103 consecutive patients from October 1, 1984, to September 20, 1988, the hospital mortality (death within 30 days or during hospitalization) has been 11.7

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAt a time when hospital mortality for adult cardiac operations is continuing to fall, the combined mitral valve coronary bypass subset remains at relatively high risk. Efforts to improve results should be directed toward a more general application of mitral reconstruction in this population, tailoring the type of repair to the pathological anatomy of valve dysfunction. Other promising therapeutic measures include the liberal use of reperfusion therapy in the acute papillary muscle dysfunction group, better selection patients for operation, and perhaps operative recommendation to a greater proportion of the more stable patients that previously were treated medically. Finally increasing the general awareness of this problem should hasten the development of improved management strategies.

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractTraumatic aortic transaction is a life‐threatening surgical emergency. Therapy must be directed at rapid repair and prevention of postoperative complications, the most serious being paraplegia. Controversy over the optimal method of repair exists‐specifically whether the use of a shunt modifies the outcome. Our series of 17 patients using left atrial to femoral bypass with the Biomedicus pump will be discussed. Preoperative preparation and operative technique will be outlined. Mortality in this series was 18%, the incidence of paraplegia wa

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe epoxy group of the epoxy compounds has an oxygen arm that can work as a flexible joint in a cross‐linking bridge and can block not only the amino group but also the carboxy group of collagen peptide. The purpose of this study is to evaluate the anticalcification efficacy of the epoxy compounds as a cross‐linking agent for xenograft bioprostheses.Porcine aortic leaflets were treated with 2% epoxy compounds and implanted in subcutaneous layer of 4‐week‐old rats. Measurement of calcium content showed that epoxy‐treated implants received a minimal calcification: mean 0.64μg/mg dry weight leaflet tissue (range 0.5–0.8;N=7) at 1 month; mean 0.94μg/mg (range 0.3–1.3;N=9) at 2 months; and mean 1.2μg/mg (range 0.5–2.1;N=10) at 3 months. Natural leaflets contained calcium of mean 0.43μg/mg. By contrast, glutaraldehyde‐preserved implants were severely calcified: mean 91μg/mg (range 41–130;N=11) at 1 month; mean 136μg/mg (range 73–205;N=16) at 2 months; and mean 170μg/mg (range 90–214;N=21) at 3 months.The epoxy compounds provide more pronounced anticalcification effects than the glutaraldehyde under pressure load

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have developed a simplified concept for a bileaflet atrioventricular prosthesis that can be constructed from a simple sheet of glutaraldehyde preserved pericardium. The valve has no rigid ring or stent and no cloth sewing ring. Insertion of the valve reestablishes normal continuity between the annulus and the papillary muscles. We have replaced the mitral valve in nine dogs using this prosthesis. All valves have been competent with excellent valve opening areas as confirmed by echo‐Doppler assessment. Studies up to 4 1/2 months have confirmed excellent hemodynamics and there has been no evidence of early tissue failure. Possible advantages of this simple valve design are improved hemodynamics, ease of construction and insertion, and low cos

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00257.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractStudies performed by other investigators have shown that a number of preimplantation processes inhibit the calcification of pieces of porcine aortic valves and of bovine parietal pericardium subcutaneously implanted in rats. To evaluate biological reactivity with these biomaterials functioning in an intracardiac position, mitral and tricuspid valve replacements were performed in young sheep to assess the effects of the following preimplantation processes: (1) surfactants, including sodium dodecyl sulfate, polysorbate‐80, Triton X‐100 and N‐lauryl sarcosine; (2) covalently bound aminohydroxypropane diphosphonic acid; (3) toluidine blue; and (4) incorporation of polyacrylamide into valvular tissues.Quantitative calcium analyses showed that only the surfactants substantially reduced calcification, and only in porcine aortic valvular bioprostheses. However, morphological studies showed that some of these agents also induced alterations that decreased the durability of the valves. Toluidine blue decreased calcification to a degree that was statistically significant, but not biologically important. Polyacrylamide incorporation and diphosphonate binding increased calcification. Thus, data regarding anticalcification treatments obtained from subcutaneous implantation studies in small animal models should be cautiously interpreted and validated by studies with intracardiac valvular implantation in large an

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00258.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractBecause late valve‐related complications such as hemolysis and thromboembolic events are considered related to flow disturbances caused by the inserted valve, velocity fields downstream of aortic valve prostheses were studied in pigs. Acute hemodynamic evaluation of size 25‐mm porcine and pericardial aortic valve prostheses 1 diameter downstream of the valve ring was performed using dynamic three‐dimensional visualization of velocity profiles and spatial distribution of turbulence.Point blood velocity signals obtained with a 1‐mm hot‐film anemometer needle probe were used to compute Reynolds normal stresses (RNS) by calculation of the turbulent velocity energy of the axial velocity component in the systole.The porcine valves caused a skewed velocity and turbulence profile revealing mean spatial systolic RNS at 70 nm−2+ 35 nm−2(+ SD). The spatial maximum RNS was 275 + 139 nm−2. Corresponding values for the pericardial valves were 20 + 11 nm−2and 72 + 46 nm−2.The pericardial valves revealed plug‐shaped velocity profiles and turbulent profiles with slightly higher RNS values at the stent posts. From a hemodynamic point of view, these acute studies indicate superiority of the pericardial valves compared to the porcine valves. The turbulent stresses found in this study are of a magnitude that may cause blood corpuscular a

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPericarbon, a new generation pericardial valve, is characterized by a single, three cuspal shaped pericardium sheet, which is sutured to a second sheet lining the inner surface of the plastic, low profile stent. A coating of hemocompatible carbon film covers all the exposed, nonbiological surfaces. Optimal preservation of collagen and graft cells is achieved by fresh tissue glutaraldehyde fixation and cusp shaping without mold.Accelerated fatigue testing showed a duration of over 150 million cycles, a figure much higher than that observed when current pericardial and porcine valves were tested with the same apparatus.Results of long‐term (>7 months, average 10.5) implantation in 20 sheep (13 mitral, 7 tricuspld) disclosed no case of mechanical failure, mild to moderate primary calcification in older explants, and significant fibrous tissue overgrowth only in the tricuspid position. Transmission electron microscopy studies revealed collagen and elastic fiber integrity, no significant plasma protein insudation, and well‐preserved graft cells. Re‐endothelialization by host cells was a regular finding on scanning electronic microscopy. Early ultrastructural nuclei of calcification were seen mostly on collagen fibers.Pericarbon presents basic changes in pericardial valve design, and optimal morphological preservation is obtained after industrial processing. Accelerated fatigue tests in vitro show long duration. At medium long‐term animal experimental follow‐up, mechanical failure was not observed; significant host tissue reaction occurred in the tricuspid but not in the mitral position; primary calcification increased progressively with time and involved mainly collag

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractProperly timed atrial systole may alter systolic performance by the mechanism of Starling's law of the heart, which states that the extent of systolic myocardial fiber shortening is dependent on the degree of diastolic fiber stretch, or preload. However, the atrial contribution to physiological need and thus is critical in developing the proper cardiac output response to exercise. Current generations of permanent pacemakers, which may have a combination of dualchamber and sensor technologies, will permit the restoration of normal cardiac physiology (AV synchrony and/or rate response) in most patients.

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1989.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY