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Biomedical subjects

Yuguo Weng

Publications and source records attributed to Yuguo Weng.

30 records · Page 2Linked to original sources
PubMed2004

Factors influencing the results of double-valve surgery in patients with fulminant endocarditis: the importance of valve selection.

BACKGROUND: Extension of infection below the aortic valve is a serious complication, especially with mitral valve involvement. Mortality is substantial and reinfection can strongly influence outcome. PATIENTS: Of 327 surgical patients with active infective aortic valve endocarditis admitted to the Deutsches Herzzentrum Berlin for surgical treatment between December 1996 and December 2003, 108 had root abscess, and 53 (25.5%) had diagnoses of secondary infective mitral valve disease (SMVD). The mean age (+/-SD) was 53 +/- 14.2 years; there were 37 men and 16 women. METHODS: The secondary lesion on the mitral valve was classified as SMVD requiring double-valve surgery (DVS). This prospective clinical and echocardiographic study revealed 2 paths of infection extension into the mitral valve. In the DVS group, 38 patients (71.7%) had tissue metastatic lesions, and 15 patients (28.3%) had a jet lesion on the mitral valve. Most patients (42) with SMVD had an aortic ring abscess as the primary lesion. RESULTS: All patients with destructive endocarditic doublevalve disease received aortic and mitral valve surgery. In 19 cases (35.8%), mitral valve reconstruction was undertaken; in 4 cases, mitral valve replacement had to be carried out after attempted mitral valve reconstruction. Concomitant mitral valve replacement because of severe damage to the valvular and subvalvular apparatus was performed in 30 patients (56.6%). Other types of surgery performed in 11 cases (20.8%) were 8 closures of a septic ventricular septal defect and 3 closures of a fistula to the right ventricle or right atrium. Twenty-seven patients were treated with a Shelhigh prosthesis, 18 were treated with double-valve replacement (both Shelhigh), and 9 were treated with an aortic Shelhigh prosthesis and concomitant mitral valve reconstruction. Homografts were used in 17 patients, with mitral valve reconstruction carried out in 10 patients and a stented mitral prosthesis in 7. In 9 cases, 2 stented valve prostheses were used. There were 14 early (60 days) deaths (26.4%). Septic shock, severe annular and subannular destruction, and poor left ventricular function (end-diastolic dimension >65 mm, ejection fraction <40%) were the significant risk factors determined in the multivariate analysis. Function of Implants: Continuous and Color Doppler Investigation: Comparative studies of 2 different implants in the aortic position were performed late postoperatively (325 +/- 251 days) for homografts and the Shelhigh stentless prosthesis. The calculated instantaneous (maximal Doppler) gradient and the mean pressure gradient through the aortic implants were 19 +/- 10.4 mm Hg and 12 +/- 5.7 mm Hg, respectively, for the homografts and 24 +/- 8.4 mm Hg and 15 +/- 4.6 mm Hg, respectively, for the Shelhigh stentless prosthesis (not significantly different for the 2 groups). There was no mitral or aortic valve dysfunction. A trivial paravalvular leakage in the mitral position in 1 patient and a pseudoaneurysm of the left ventricular out- flow tract without leakage or valvular dysfunction in another were diagnosed by postoperative Doppler investigation. CONCLUSIONS: The mortality in patients with destructive endocarditis requiring DVS depends mostly on the patients' preoperative hemodynamic situation. The risk of reinfection can be minimized if valve substitutes are properly selected (homografts, Shelhigh No-React SuperStentless and No-React BioConduit in the aortic position, or Shelhigh BioMitral in the mitral position). Concomitant mitral valve reconstruction procedures do not increase the risk of mitral reinfection.

Endocarditis↗
PubMed2003

Stentless aortic valves as an alternative to homografts for valve replacement in active infective endocarditis complicated by ring abscess.

BACKGROUND: The valve substitute of choice in active infective aortic valve endocarditis complicated by annulus abscess in our institution is the cryopreserved homograft. To avoid implantation of any prosthetic material, the Shelhigh No-React stentless valves and conduits may be considered an alternative when no suitable homograft is available. METHODS: Between March 1986 and January 2001, 452 homografts were implanted in the aortic position. From January 2000 to August 2001, 75 Shelhigh No-React prostheses were implanted at our institution. In 25 consecutive patients (study group) with aortic annulus abscess, urgent aortic valve replacement with the Shelhigh SuperStentless and Stentless Aortic Valve Conduit was undertaken. Patients (16 male, 9 female; age, 49 +/- 19 years) were studied with follow-up until March 2002. The control group comprised 68 consecutive historical patients (46 male, 22 female; age, 53 +/- 14.4 years) with similar disease treated between January 1997 and December 1999 in whom an aortic homograft was implanted. This group was also followed up until March 2002. Demographic data and preoperative characteristics of the patients were without significant differences. Patients were studied by echocardiography. RESULTS: Sixty-day mortality was 16% (11 patients) in the control group compared with 12% (3 patients) in the study group. Recurrent infection occurred in 4% in both groups. The instantaneous and mean Doppler gradients yielded no significant differences (19.4 +/- 10.4 mm Hg and 11.8 +/- 5.7 mm Hg versus 18.2 +/- 8.7 mm Hg and 10.9 +/- 5.3 mm Hg, respectively). The mean effective orifice area calculated from Doppler flow velocity for the stentless valve was 2.3 +/- 0.6 cm2. Preoperative evaluation of left ventricular dimensions and global left ventricular systolic function did not vary significantly between the two groups. However, postoperatively evaluated left ventricular end-diastolic diameter dimensions in the study group were significantly smaller than those in the control group (47.6 +/- 7.9 mm versus 56 +/- 9.5 mm; p = 0.05). Ejection fraction was similar in both groups (56.2% +/- 12.8% for the study [Shelhigh] and 52.6% +/- 16.8% for the control [homograft] group). CONCLUSIONS: Our experience with both the Shelhigh No-React SuperStentless and Stentless Aortic Valve Conduit in patients with native or prosthetic aortic valve endocarditis appears to demonstrate good results, similar to those of cryopreserved homografts. Ease of implantation and favorable effective orifice area and pressure gradients, as well as the No-React anticalcification treatment, are promising factors.

Abscess↗
PubMed2003

Outpatients on mechanical circulatory support.

BACKGROUND: As waiting periods for heart transplantation have lengthened, the application of long-term mechanical circulatory support (MCS) has become more common in patients presenting with cardiogenic shock. Anticipating increased long-term MCS, a policy to discharge patients home has been instituted. This study compares the results of outpatient on MCS to a group of patients remaining hospitalized. METHODS: We report our 10-year experience with 108 patients on MCS, who were supported for more than 3 months. Group A consisted of 38 patients (25 Novacor, 13 Berlin Heart) who underwent assist implantation from 1996 to 2001. They had a mean support time of 454 days (range 100 to 1074 days) and spent a mean of 326 days (range 20 to 769 days) at home. Group B consisted of 70 patients (24 Novacor, 46 Berlin Heart) who underwent assist implantation between 1991 and 2000. They had a mean support time of 234 days (range 95 to 795 days) and were not discharged. The patients were monitored for complications, hospital readmissions, and causes of death including infections and thromboembolic and bleeding events during the MCS time. RESULTS: Group A total mortality was 16% (6/38). Two patients died from cerebral embolism, one from cerebral hemorrhage, two from systemic infection, and one from multiorgan failure. Thirty-two patients (84%) required 95 readmissions to the hospital due to cerebral embolism (n = 9), bleeding (n = 1), wound infections (n = 23), coagulation disorder (n = 13) for heart transplantation (n = 5), and (n = 44). In group B the mortality was 43% (30/70) for noncardiac reasons and thus significant higher (p = 0.004, chi2 test). Causes of death were cerebral embolism (n = 5), cerebral hemorrhage (n = 7), systemic infection (n = 14, significantly higher, p = 0.04, chi2 test), and multiorgan failure (n = 4). CONCLUSIONS: Our experience demonstrates that MCS can be used in outpatients without increased mortality and with an acceptable rate of readmissions (2.8/patient). It ensures the survival of the patient, enables recovery from multiorgan failure, and offers an acceptable quality of life.

Adolescent↗
PubMed2003

New approach in treatment of acute cardiogenic shock requiring mechanical circulatory support.

In 12 patients with acute cardiogenic shock who required mechanical circulatory support a short-term Abiomed BVS 5000 extracorporeal assist device was implanted using the inflow and outflow cannulas of the BerlinHeart extracorporeal assist device. In 7 patients suitable for long-term support the Abiomed pumps were later exchanged for BerlinHeart pumps. This approach avoids the risks associated with repeat sternotomy and use of cardiopulmonary bypass and decreases the total costs of patient care.

Acute Disease↗
PubMed2003

Donor-transmitted coronary atherosclerosis.

BACKGROUND: Autopsies show that coronary atherosclerosis is present frequently in the young and healthy. However, according to our former guideline, we performed pre-transplant evaluation without coronary angiogram in donors <60 years. The purpose of this study is to evaluate to what extent native coronary atherosclerosis is transmitted through heart transplantation. METHODS: Between April 1986 and December 2000, a total of 1253 patients underwent heart transplantation at our institution. If coronary evaluation with coronary angiogram or autopsy had been performed within 6 months after transplantation, we regarded focal and non-circumferential atherosclerosis with >or=50% stenosis in proximal segments of at least 1 coronary vessel of the donor heart as transmitted, native coronary atherosclerosis, rather than newly developed transplant vasculopathy. RESULTS: We excluded 85 of 1253 (6.8%) cases because coronary evaluation was not performed within 6 months (n = 45) or because hearts underwent angiography during pre-transplant evaluation (n = 40). Of these, 2 patients with significant coronary atherosclerosis underwent transplantation and concurrent coronary artery bypass grafting. The prevalence of significant (stenosis >or=50%) and inadvertently transmitted coronary atherosclerosis was 7.0% (82/1168). CONCLUSION: The prevalence of coronary atherosclerosis in patients who underwent angiography within 6 months after transplantation was 5.2% (49/950). Among subjects who had autopsies within the first 6 months after heart transplantation, we found significant coronary atherosclerosis (stenosis >or=50%) 15.1% (33/218), and among those with early graft failure (<10 days after transplantation), the prevalence was 22.8% (26/114). The prevalence of coronary atherosclerosis in the donor pool is high, and donor screening without coronary angiogram overlooks significant coronary atherosclerotic lesions (stenosis >or=50%) in a considerable number of cases (7.0%). Because donor-transmitted coronary atherosclerosis is a risk factor in short-term (early graft failure) survival after heart transplantation, we have now changed our policy to include coronary angiography as a standard in screening donors >or=40 years. However, to what extent donor coronary atherosclerosis is accepted undoubtedly must be made arbitrarily until an evidence-based algorithm becomes available.

Adult↗
PubMed2003

Heart transplantation in children after mechanical circulatory support with pulsatile pneumatic assist device.

BACKGROUND: Mechanical support with a pulsatile pneumatic ventricular assist device (VAD) is a complex rescue procedure performed in children with untreatable cardiogenic shock. Its impact on early and long-term survival after subsequent heart transplantation (HTx) remains to be determined. METHODS: We reviewed retrospectively the course of 95 children (median age, 8 years; range, 8 days-17 years; body weight, 24 kg; range, 3-110 kg) who underwent HTx. Group A, the elective-HTx group, consists of 33 children who were treated as outpatients before transplantation. Group B, the emergency-HTx group, has 44 children who were critically ill and hospitalized before transplantation but without ventricular assist devices, whereas Group C, the VAD-HTx group, consists of 18 children resuscitated and supported with pulsatile pneumatic VADs for a median time of 20 days. RESULTS: Overall actuarial survival after cardiac transplantation was 86% at 1 month, 82% at 1 year, and 78% at 5 years, without significant differences among the 3 sub-groups. Group A had the best long-term survival rate, 88% at 1 month, 88% at 1 year, and 80% at 5 years. Group B had a survival rate of 88% at 1 month, 82% at 1 year, and 79% at 5 years. Group C had a survival rate of 72% at 1 month, 72% at 1 year, and 72% at 5 years. We found no differences in neurologic outcome, acute cardiac rejection, or transplant failure. The survival rate was significantly better in the children with cardiomyopathy compared with those with congenital heart defects (p = 0.014). CONCLUSIONS: Bridging to HTx with a pulsatile pneumatic VAD is a safe procedure in pediatric patients. After HTx, overall survival of these children is similar to that of patients who were bridged with inotropes or who were awaiting heart transplantation electively.

Actuarial Analysis↗
PubMed2002

[Heart assist systems--current status].

BACKGROUND: Heart failure is the leading cause of death in the developed countries. Organ-preserving operative procedures on the failing heart like coronary artery bypass procedures or resection of left ventricular aneurysms are part of the routine care in cardiac surgery today. Terminal heart failure refractory to optimized drug therapy, however, will require a heart transplantation or the implantation of artificial blood pumps. While heart transplantation has proven to provide excellent long-term results with 10-year survival rates at 50%, it will remain a casuistic therapy, limited by the comparatively small number of procedures which can be performed. ARTIFICIAL BLOOD PUMPS: The current status of development of artificial blood pumps is represented by the broad availability of partially-implantable electric motor-driven left ventricular assist devices (LVAD), which still require a percutaneous cable for energy supply and device control from external sources while the blood pump itself resides inside the body. The recently introduced axial-flow devices (DeBakey, Jarvik 2000 and HeartMate II LVADs) deliver a continuous blood flow and obviously provide distinct advantages with regard to a reduction in size, weight and energy demands, simplified implantation technique and device control when compared to the previously available partially-implantable electric motor-driven pulsatile blood pumps (Novacor N100, TCl Heart Mate LVADs). The first systems designed for long-term or permanent use (Lion Heart LVAD, AbioCor replacement heart) are completely implantable devices featuring percutaneous energy transmission and device control. However, the latter are more complex devices and their clinical application is still limited to a small number of cases, which precludes a judgment about their potential at this time. INDICATIONS: The use of paracorporeal pneumatically accentuated blood pump systems is still indicated in cases of most severe biventricular heart failure and multiorgan failure or if only short- to mid-term circulatory support is anticipated. Well established indications for utilization of artificial blood pumps are the bridge-to-transplant procedure, which yields results comparable to primary heart transplantation, and acute cardiac failure following myocardial infarction or cardiac surgical procedures. In newborns and children, encouraging results were obtained when miniaturized blood pumps of the Berlin Heart System were utilized for heart failure in myocarditis or dilative cardiomyopathy. With advanced reliability of artificial blood pumps and in face of the high incidence of heart failure, especially in the older age group, the long-term application of artificial bloods pump appears to be justified.

Equipment Design↗
PubMed2002

Implantation of a left ventricular assist device in situs inversus.

A 42-year-old man with situs inversus was referred to our institution because of end-stage ischemic cardiomyopathy. Cardiac arrest occurred after admission, and the patient underwent cardiopulmonary resuscitation. An extracorporeal left ventricular assist device (Berlin Heart) was implanted as a bridge to transplantation. This is one of the first reports of left ventricular assist device implantation in a patient with situs inversus and ischemic cardiomyopathy.

Adult↗
PubMed1999

Pulsatile pediatric ventricular assist devices: Current results for bridge to transplantation.

While pulsatile ventricular assist devices have gained widespread use in adult patients awaiting heart transplantation, only very limited experience with these devices exists in the pediatric population. In the past mostly non-pulsatile systems such as ECMO have been used to support pediatric patients with heart failure for very limited periods of time. Only recently have miniaturized pulsatile devices became available. This article describes the technical characteristics of these devices which have been implanted at the Deutsches Herzzentrum Berlin since 1992. The Berlin Heart assist device has since been used in 34 children between the ages of 6 days and 16 years. We report our strategy in patient selection, perioperative care and subsequent heart transplantation. The current literature on mechanical circulatory support in children is reviewed. Copyright 1999 by W.B. Saunders Company

Journal Article↗
PubMedDate not supplied

Effects of basic fibroblast growth factor and transforming growth factor-beta on maturation of human pediatric aortic cell culture for tissue engineering of cardiovascular structures.

Optimal in vitro conditions are necessary for the development of a strong, well structured, and functional tissue engineered cardiovascular structure eventually designed for implantation. To further optimize in vitro conditions for cell proliferation and extracellular matrix formation in tissue engineering of cardiovascular structures, in this study, ascorbic acid and growth factors as additives to standard cell culture medium were evaluated for their effect on tissue development in vitro. Biodegradable polymer patches [polyglycolic acid (PGA) coated with poly-4-hydroxybutyrate (P4HB)] were seeded with human pediatric aortic cells and cultured for 7 and 28 days. Group A was cultured with standard medium (DMEM with 10% fetal calf serum and 1% antibiotics) supplemented with ascorbic acid; group B was cultured with standard medium plus ascorbic acid and basic fibroblast growth factor (bFGF); group C was cultured with standard medium adding ascorbic acid and transforming growth factor (TGF). Analysis of the cell seeded polymer constructs included DNA assay, collagen assay, and histologic and immunohistochemical examination for cell proliferation and collagen formation. After 7 and 28 days of culture, group B and group C showed a significantly higher DNA content compared with group A. The addition of bFGF (group B) led to a markedly higher collagen synthesis after 28 days of culture compared with the additives in groups C and A. The histologic and immunohistochemical examination also revealed a more dense, organized tissue development with pronounced matrix protein formation in the tissue engineered structures in group B after 28 days of culture. When seeded on to the polymeric scaffold, human vascular cells proliferate and form organized cell tissue after 28 days of culture. The addition of bFGF and ascorbic acid to the standard medium enhances cell proliferation and collagen synthesis on the biodegradable polymer, which leads to the formation of more mature, well organized tissue engineered structures.

Aorta↗