A 57-year-old male was treated for fungal endocarditis caused by Candida parapsilosis which precipitated severe cardiac valve vegetation and insufficiency. His condition resulted from a three-month installation of a central venous catheter for hyperalimentation and chemotherapy following total gastrectomy for gastric cancer. Aortic valve replacement combined with fluconazole administration resulted in satisfactory recovery with no adverse events during an 18-month follow up period.

How to cite: Inoue, Y., Yozu, R., Ueda, T., & Kawada, S. (1998). A case report of Candida parapsilosis endocarditis. The Journal of heart valve disease, 7(2), 240–242.

The incidence of prosthetic valve endocarditis is 2-4%; in most cases the involved organisms are Staphylococcus epidermidis and Staph. aureus. Fungal endocarditis is much less common (incidence < 0.1%), but it is often fatal, with a long-term mortality rate of 90-100%. Most fungal endocarditis cases occur after aortic valvular surgery, due to Candida sp. Late-onset symptoms, long-term development and aggressive nature of the fungus makes its eradication complicated and treatment difficult. Fungal valvular mycoses produce systemic embolization and cause serious perioperative bleeding on resection of infected tissue. Usually surgery includes aortic root replacement with an aortic homograft conduit after radical debridement, to attain local sterilization. This report describes a patient with complex infection, requiring replacement of an infected prosthetic valve with an aortic homograft conduit, aggressive and radical debridement of infected tissue, and reconstruction using biologic tissues. The case demonstrates the importance of perioperative and long-term antifungal treatment and presents a modified 'Cabrol procedure' to prevent critical intraoperative hemorrhage.

How to cite: Remsey, E. S., & Lytle, B. W. (1998). Repair of fungal aortic prosthetic valve endocarditis associated with periannular abscess. The Journal of heart valve disease, 7(2), 235–239.

Background and aims of the study: This study was performed to evaluate the role of collagen fibrils, cellular elements and matrix proteins in calcification of glutaraldehyde (GA)-fixed bioprosthetic material.

Methods: Lyoplant (lyophilized bovine pericardium, type I collagen) was processed according to three protocols. DF-group (double fixation): after conventional fixation in GA (0.5% for 72 h; storage 0.25%) Lyoplant was implanted subcutaneously into rats for 5 days. Specimens were explanted and re-fixed (conventional fixation), followed by autologous or homologous reimplantation in rats for 21 or 63 days. CF-group (conventional fixation): Lyoplant patches were conventionally fixed (as DF-group), kept in 0.9% saline for one week, and then autologously and homologously reimplanted. GF-group (high-concentration GA): Lyoplant patches were processed (as GF-group) but 0.5% GA was used for tissue storage. Explanted specimens were studied by light microscopic histochemistry; calcium contents were measured by atomic absorption spectroscopy.

Results: Severe calcification occurred in the DF-group without differences between autologous and homologous reimplantation. In CF- and GF-groups, calcification was negligible, but immunologic response against homologous implants was accompanied by increased calcium content. Histologic characterization of matrix material in calcified areas revealed oxyphilic glycoproteins, identified as sialoglycans.

Conclusions: Modification of extracellular matrix by GA is assumed as essential to cause calcification of bioprosthetic material. Calcium deposition and accumulation of sialoglycans are simultaneous events. A specific role of this glycoprotein for calcification has to be considered.

How to cite: Grabenwöger, M., Böck, P., Fitzal, F., Schmidberger, A., Grimm, M., Laufer, G., Bergmeister, H., & Wolner, E. (1998). Acidic glycoproteins accumulate in calcified areas of bioprosthetic tissue. The Journal of heart valve disease, 7(2), 229–234.

Background and aims of the study: Homograft mitral valve replacement may offer a superior alternative to replacement with a prosthetic valve. The authors' early experience with this technique is reported.

Methods: Between May 1994 and May 1995, 24 patients (19 males, five females; age range 17 to 49 years) underwent homograft mitral valve replacement (HMVR) at the authors' institution. The etiology was rheumatic in all patients; 22 had severe calcific mitral stenosis (MS) and two had combined MS and severe mitral regurgitation (MR).

Results: There were three early deaths (12%) and two late deaths (8%). In three patients the homograft had to be explanted due to severe MR at six weeks, 10 weeks and 12 months, respectively. Mean follow up was 18 months (range: 12 to 25 months). Postoperative echocardiography showed trivial or mild MR in 12 patients and moderate MR in four. Mitral stenosis was absent in all patients (mean mitral valve area 2.5 cm2). Sixteen patients showed satisfactory homograft valve function at follow up. The valve explanted after six weeks showed normal cusp architecture, endothelial growth and incorporation of the pericardial strip and complete healing of the papillary muscle junction. Magnetic resonance imaging in 12 patients showed normal appearance and function of the homografts.

Conclusions: The authors' experience suggests that homograft mitral valve replacement can be performed with good early results.

Hoew to cite: Kumar, A. S., Kumar, D. A., Chander, H., & Saxena, A. (1998). Experience with homograft mitral valve replacement. The Journal of heart valve disease, 7(2), 225–228.

Background and aim of the study: The study aim was to collect intermediate clinical data on the TEKNA bileaflet valve.

Methods: This nine-center clinical study involved 884 patients implanted between June 1990 and October 1993. The population consisted of 522 (59.0%) males and 362 (41.0%) females. Mean age at implant was 59.1 +/- 11.8 years (range: 14.7 to 88.4 years). Indication for valve replacement was dependent on the position: stenosis was the predominant reason in the aortic position; regurgitation was more pronounced for the mitral position. A total of 261 (29.5%) patients underwent concomitant procedures. Mean follow up is 2.7 +/- 1.2 years; total follow up is 2386.1 patient-years (pt-yr).

Results: Total operative (< or = 30 days postoperative) mortality rate was 3.7%; seven patients (0.8%) died due to valve-related causes. Total postoperative (> 30 days postoperative) mortality rate was 2.5%/pt-yr and included a valve-related mortality rate of 1.1%/pt-yr. The following valve-related complication rates (%/pt-yr) were reported for the long-term postoperative period: thromboembolism 0.6; valve thrombosis 0.3; bleeding events 1.5; non-structural deterioration 0.6; and endocarditis 0.4. No structural valve deterioration was reported. Actuarial freedom at four years was: overall survival rate 86.9 +/- 1.4%; valve-related survival rate 94.7 +/- 1.0%; freedom from thromboembolism 96.8 +/- 0.9%; valve thrombosis 99.3 +/- 0.3%; endocarditis 98.5 +/- 0.5%; bleeding events 94.3 +/- 1.0%; and non-structural deterioration 98.2 +/- 0.6%.

Conclusions: The data indicate that observed mortality is due mainly to non-valve-related disorders. Risk of thromboembolic and bleeding events was low (0.9%/pt-yr and 1.5%/pt-yr, respectively). We conclude that this valve is safe and efficacious for use.

How to cite: Seybold-Epting, W., Limet, R., Scheld, H., Frank, G., Hannekum, A., David, M., Tatou, E., Wolner, E., Loisance, D., Kassal, H., & Ryba, E. A. (1998). Intermediate follow up of the TEKNA bileaflet valve. The Journal of heart valve disease, 7(2), 219–224.

Background and aims of the study: Previous studies have shown that the effective orifice area of an aortic prosthetic valve may be too small in relation to the patient's body surface area, resulting in abnormally high gradients. The consequences of this condition, termed prosthesis-patient mismatch, have not been fully studied. The study objective was to determine if the condition has a detrimental effect on symptomatic and hemodynamic status, morbidity and mortality of patients undergoing aortic valve replacement.

Methods: A cohort of 392 patients was prospectively followed for up to seven years after implantation of a Medtronic Intact bioprosthesis. Doppler echocardiography was performed annually in 72 patients. Based on previous studies, presence of mismatch was defined as an indexed valve area < or = 0.85 cm2/m2.

Results: Mismatch was associated with less postoperative improvement of NYHA functional class (p < 0.009) independently of other predictors, such as age and preoperative functional class, but had no significant impact on patient survival (mismatch: 75 +/- 4%, no mismatch: 79 +/- 3%; p = 0.59) and valve-related morbidity up to seven years. Cardiac index was similar in patients with and without mismatch up to three years after operation but decreased significantly thereafter only in patients with mismatch (-0.54 +/- 0.32 versus -0.17 +/- 0.49 l/min/m2; p = 0.04). Likewise, the mean transprosthetic gradient, which was higher at one year after operation in patients with mismatch (22 +/- 8 versus 15 +/- 7 mmHg), increased significantly (+6 +/- 6 versus +1 +/- 1 mmHg; p = 0.008) only in this group during follow up.

Conclusions: Patients with mismatch have less symptomatic improvement and worse hemodynamics that continue to deteriorate with time. However, medium-term prognosis (up to seven years) is relatively good. Further studies are necessary to determine the longer-term effects of mismatch on morbidity and mortality.

How to cite: Pibarot, P., Dumesnil, J. G., Lemieux, M., Cartier, P., Métras, J., & Durand, L. G. (1998). Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity and mortality after aortic valve replacement with a bioprosthetic heart valve. The Journal of heart valve disease, 7(2), 211–218.

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how to cite: Rahimtoola S. H. (1998). Valve prosthesis-patient mismatch: an update. The Journal of heart valve disease, 7(2), 207–210.

Background and aims of the study: This study was performed to identify the physical and histopathologic characteristics of different sections of glutaraldehyde-tanned bovine pericardium.

Methods: Ten pericardial sacs were obtained from animals aged from 18 to 36 months. Physical tests included shrinkage and mechanical resistance (rupture, elongation, tenacity index). Collagen and elastic fibers were evaluated in Gomori's trichrome-stained sections, hematoxylin and eosin, by PAS and Verhoeff's method. Studied areas were proximal to the great arteries, and the right atrial, right ventricular, left ventricular and left atrial regions.

Results and conclusions: Results showed that bovine pericardium does not have enough regional differences to identify any single region for bioprosthesis manufacture. However, histopathology showed better preservation of collagen and elastic fibers in the right ventricular region, implying that this area is more adequate as bioprosthetic material.

How to cite: Braile, D. M., Soares, M. J., Souza, D. R., Ramirez, V. D., Suzigan, S., & Godoy, M. F. (1998). Mapping of bovine pericardium: physical and histopathologic tests. The Journal of heart valve disease, 7(2), 202–206.

Background and aims of the study: The study aimed to determine the clinical performance of bovine pericardial aldehyde-treated products alone or in combination with aortic leaflets of porcine origin. These included a composite porcine stentless aortic valve attached to a scalloped pericardial tube (BSAV), and valved and non-valved bovine pericardial conduits for use in left-sided heart lesions (BPG).

Methods: For BSAV grafts, between January 1990 and August 1996, 163 patients (119 males) had their aortic valves replaced by SJM Biocor BASV. Mean age was 37.9 +/- 17.6 years (range: 1 to 76 years). Rheumatic heart disease sequelae (n = 72) and replacement of a prosthetic heart valve (n = 46) were predominant. Preoperative NYHA functional class showed 90 patients (55.2%) in class III and 50 (30.7%) in class IV. BPVC and NVPC grafts were used in 166 patients: acute aortic dissection was the main indication in 52 (31.3%) and chronic in 36 (21/7%). The ascending aorta was involved in 141 patients (84.9%); grafts were seldom used at other sites. In most patients the graft implanted was either a non-valved (n = 79) or a valved (n = 75) pericardial conduit. Twelve patients had a localized lesion and required a patch repair.

Results: For BASV grafts, the non-valve-related hospital mortality rate was 4.9%. There were 14.7% non-fatal complications with full recovery of all patients. Mean follow up in 141 patients was 3.0 +/- 1.4 years (range: 1 month to 7.2 years); 14 patients were lost to follow up. Late, non-conduit-related, mortality occurred in seven patients (4.9%). Eight patients underwent reoperation. The current clinical follow up of 127 patients has shown 118 (92.9%) with competent valves and nine (7.0%) with mild stable aortic insufficiency. For BPVC and NVPC grafts, hospital mortality rate was 16.9%, death being related to poor preoperative clinical condition. Postoperative follow up was accomplished in 125 patients; reoperation was necessary in seven patients. Histology showed good tissue preservation up to five years; echocardiography revealed satisfactory findings. No valved conduit had to be reoperated for valve or pericardial tissue wear.

Conclusions: Clinical results of left-sided heterologous pericardial grafts have shown excellent performance over time. The BASV (over seven years) and BPVC and NVPC (eight years) have demonstrated superior results as aortic valves alone or in combination with a pericardial conduit.

How to cite: Vrandecic, M., Gontijo Filho, B., Fantini, F., Barbosa, J., Martins, I., de Oliveira, O. C., Martins, C., Max, R., Drumond, L., Oliveira, C., Ferrufino, A., Alcocer, E., Silva, J. A., & Vrandecic, E. (1998). Use of bovine pericardial tissue for aortic valve and aortic root replacement: long-term results. The Journal of heart valve disease, 7(2), 195–201.

Background and aims of the study: Glutaraldehyde cross-linked bovine pericardium was post-treated with homocysteic acid in order to bond unreacted glutaraldehyde groups, and preserved in aldehyde-free solution to reduce the toxicity and calcification potential of the tanned tissue. The study aim was to verify the efficacy and preservation of chemical and mechanical properties of pericardial tissue treated in this way.

Methods: Detoxification efficacy was tested by measuring free aldehyde groups and by in vitro cultivation of human endothelial cells on pericardial samples. Material stability tests included mechanical characterization, shrink temperature measurement, pronase digestion resistance and amino acid analysis after acid hydrolysis. The effect of treatment on fatigue resistance was evaluated by monitoring changes in permeability and compliance caused by 15 x 10(6) cycles of pulsatile stress.

Results: Detoxified samples showed negligible glutaraldehyde residues and significantly improved endothelial cell proliferation compared with conventionally treated samples. Chemical and mechanical properties were similar in detoxified and glutaraldehyde-treated samples. Tissue fatigue behavior was not modified by homocysteic acid treatment.

Conclusion: Homocysteic acid treatment effectively reduces toxicity but does not affect the stability of glutaraldehyde cross-linked pericardium.

How to cite: Stacchino, C., Bona, G., Bonetti, F., Rinaldi, S., Della Ciana, L., & Grignani, A. (1998). Detoxification process for glutaraldehyde-treated bovine pericardium: biological, chemical and mechanical characterization. The Journal of heart valve disease, 7(2), 190–194.

Background and aims of the study: Pericarbon is a new-generation bovine pericardial bioprosthesis designed to withstand mechanical wear. Following optimal in vitro testing and animal experiments, clinical trials were initiated in many European centers and explants sent to our department for pathological evaluation. This included gross, radiographic, histologic and ultrastructural investigations.

Methods: Between 1986 and 1996, 24 bioprostheses (eight aortic, 11 mitral, two mitro-aortic, one tricuspid) were collected from 22 patients (10 males and 12 females; mean age 57.0 +/- 18.9 years) either at autopsy (nine) or reoperation (15).

Results: Ten bioprostheses explanted < 2 months after surgery were either normal or failed because of surgical problems or non-structural causes. Among the other 14 bioprostheses (mean placement 41.9 +/- 23.6 months; range: 7 to 90 months), structural deterioration occurred in seven and was due to dystrophic calcification with stenosis in five (three aortic, two mitral), mixed lesion in one (mitral), and incompetence in one by calcium-related commissural tear (mitral). At the ultrastructural level, calcification was detected either on cell debris or upon collagen fibers. No bioprosthesis failed because of fibrous tissue overgrowth. Of the remaining seven bioprostheses, vegetative endocarditis occurred in two, thrombosis in one, and aseptic paravalvular leak in one; whereas three showed no signs of dysfunction.

Conclusions: This pathologic experience with the Pericarbon valve showed calcification to be the main cause of late structural failure, causing mainly cusp stiffness and bioprosthesis stenosis. Tissue rupture or abrupt dysfunction never occurred. Thus, prevention of mineralization remains the main challenge.

How to cite: Valente, M., Ius, P., Bortolotti, U., Talenti, E., Bottio, T., & Thiene, G. (1998). Pathology of the Pericarbon bovine pericardial xenograft implanted in humans. The Journal of heart valve disease, 7(2), 180–189.

Background and aims of the study: The study aim was to assess tissue quality and host-biomaterial interactions in clinical bioprostheses fabricated from bovine pericardium preserved by dye-mediated photooxidation, but not glutaraldehyde-pretreated.

Methods: Ten aortic valves explanted for regurgitation after 8-23 months' function from 10 patients aged 67-83 years were analyzed by gross and dissecting microscope examination, radiography and light microscopy.

Results: Each valve had one to several commissural-basal tears (5 mm) to complete leaflet detachment (four valves). The pattern of tearing was consistent among valves and suggested that a mechanism of design-related proximal inflow surface cuspal abrasion against Dacron cloth was contributory. Mild cuspal sagging/stretching was noted in five valves, pannus overgrowth was mild, and there was no evidence of infection or macroscopic thrombus. Microscopically, tissue distant from tears in all valves had an essentially intact but acellular collagenous matrix, was devoid of residual connective tissue cells and host inflammatory cells, with mild fragmentation of the inflow collagen bundles, and showed no evidence of endothelialization. Despite radiographs uniformly negative for mineralization, focal intrinsic cuspal microcalcification was noted histologically in four valves.

Conclusions: Design-related and largely abrasion-induced tearing caused failures of this cohort of photooxidized pericardial valves. Nevertheless, this nonglutaraldehyde-preserved photofixed pericardial tissue from valves suffering design-related cuspal tears to two years postoperatively remained without significant degradation, inflammation, infection, thrombus, pannus or calcification.

How to cite: Schoen F. J. (1998). Pathologic findings in explanted clinical bioprosthetic valves fabricated from photooxidized bovine pericardium. The Journal of heart valve disease, 7(2), 174–179.

Background and aims of the study: Reduction of biomaterial calcification is an important aim in the basic research of biological heart valves. An in vitro model was used to investigate the influence of serum calcium concentration and surface coverage with cells or basal proteins on calcium uptake of bovine pericardium.

Methods: Samples of glutaraldehyde-tanned bovine pericardium, stored in formaldehyde and detoxified with borohydride were incubated for two weeks with cell culture medium containing low (1.0 mmol/l) or physiologic (2.3 mmol Ca/l) calcium concentration. Specimens were either unseeded, completely surface-covered with rat fibrocytes (rf) or fibrin (fi), or incompletely seeded with rabbit cells (re). Quality of surface coverage was assessed by surface scanning electron microscopy and calcium content by atomic absorption spectroscopy.

Results: Serum calcium had a significant influence on calcium uptake (low versus physiological (1.58 +/- 2.45 mg/g versus 8.10 +/- 1.73 mg/g wet wt, p < 0.001). This may explain early calcification of bioimplants in children and patients on dialysis. Surface coverage significantly reduces calcium uptake (fi, 1.20 +/- 0.41 mg/g, rf, 4.20 +/- 1.70 mg/g, p < 0.001) but complete coverage is necessary (re, 6.98 +/- 1.64 mg/g, NS).

Conclusions: In vitro testing of calcium uptake has proven to be a valuable tool for evaluation of biomaterial calcification.

How to cite: Dahm, M., Dohmen, G., Prüfer, D., Krummenauer, F., Hafner, G., & Oelert, H. (1998). Determinants of calcium uptake of bovine pericardium for heart valve replacement: results of in vitro studies. The Journal of heart valve disease, 7(2), 170–173.

We discuss the clinical assessment of heart valve substitutes, primarily with regard to pre-market evaluation. We concentrate on the current FDA heart valve guidance document. This guidance is self-acknowledged to be an evolving document, scheduled to be revised between three and five years after its initial release on December 1993. We outline the history and some of the strengths of the present system, and discuss areas for possible improvement. We selected one important statistical issue to address thoroughly how to compute the confidence limit of a linearized rate.

How to cite: Grunkemeier, G. L., & Anderson, W. N., Jr (1998). Clinical evaluation and analysis of heart valve substitutes. The Journal of heart valve disease, 7(2), 163–169.

The use of animals to predict prosthetic valve performance in humans has now been in operation for over 25 years. Studies have focused on improvements in structural integrity, anti-thrombogenicity and anticalcification, and provide extensive in vivo analysis and validation of a valve before its clinical evaluation. Many animal models have been developed for such investigations, including calves, goats, pigs, baboons, dogs and adult sheep. Recent models used to assess prosthetic mitral valves have involved site-specific testing in several species; the present study represents the largest series of orthotopically implanted stentless bioprosthetic aortic valves and the first to utilize a juvenile sheep model for the aortic position.

How to cite: Salerno, C. T., Droel, J., & Bianco, R. W. (1998). Current state of in vivo preclinical heart valve evaluation. The Journal of heart valve disease, 7(2), 158–162.

Background and aims of the study: The current standards for accelerated heart valve testing have considerable differences in test conditions. Another problem arises from the fact that such test systems are not standardized at all. It was shown earlier that different test systems generate totally different valve loading, even if operating at standard conditions. The present study aimed to improve this unsatisfactory situation and to develop a new concept where actual loading of valves is measured either in vitro or in vivo under physiologic conditions and subsequently to reproduce these conditions during accelerated testing.

Methods: Integral loading forces at valve closure were measured for several valve types using a piezoelectric force ring within a real-time circulatory mock loop under physiologic conditions. This facilitated definition of a physiologic loading range. Physiologic loading was subsequently reproduced in a single-chamber accelerated test system. Working conditions obtained in terms of stroke, bypass flow and compliance served as design criteria for a new test chamber and a complete 12-chamber accelerated testing system.

Results: The integral loading obtained using the force ring showed a correlation with previous in vitro and in vivo results of strain-gauged valves. Loading forces for mechanical valves are about one order of magnitude higher than for bioprosthetic valves and are strongly related to cardiac output for both valve types. At physiologic loading, however, the differential pressures across the valves are considerably below those given in FDA guidelines.

Conclusions: This pilot study demonstrates that physiologic valve loading is reproducible over a wide range under appropriate testing conditions. It also showed that, at the back-pressures of the current standards, the loading forces during accelerated testing exceed the real-time loading forces by far and, thus, may provide unrealistically high valve loads. These initial findings indicate that amendments of the currently valid standards may be need to be accorded.

How to cite: Reul, H., & Potthast, K. (1998). Durability/wear testing of heart valve substitutes. The Journal of heart valve disease, 7(2), 151–157.

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How to cite: Hwang N. H. (1998). Cavitation potential of pyrolytic carbon heart valve prostheses: a review and current status. The Journal of heart valve disease, 7(2), 140–150.

The authors recommend changes to the paradigm employed in the current ISO Heart Valve Standard (ISO 5840) so that future patients who receive a heart valve prosthesis are assured of a device that will function with minimal complications for at least 25 years. Based on valve failures of the past decade, it is clear that current standards are inadequate because present-day Standards and Regulatory Agencies operate in a manner which inhibits innovation and creativity. Thus, engineers and scientists in this field react to problems, rather than proact. As we approach the new millennium, the authors consider it time to rethink the ground rules.

How to cite: Yoganathan, A. P., Ellis, J. T., Healy, T. M., & Chatzimavroudis, G. P. (1998). Fluid dynamic studies for the year 2000. The Journal of heart valve disease, 7(2), 130–139.

The international use of medical device standards is expanding for both economic and regulatory reasons. It is no longer adequate to have standards that only specify measurement methods and labeling for a product. An effort needs to be put forth between industry, academia and government to promote standards that also include a minimum set of acceptable performance criteria. This will allow for a less subjective evaluation of the conformance of the medical device to the appropriate standard as well as promote a uniform set of minimal performance expectations for a class of products among consumers.

How to cite: Mueller, E. P., & Regnault, W. F. (1998). Replacement heart valves and performance standards. The Journal of heart valve disease, 7(2), 125–129.

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How to cite: Nolan S. P. (1998). The future of heart valve standards. The Journal of heart valve disease, 7(2), 123–124.