We describe two cases of successful management by native valve salvage of an uncommon tricuspid valve regurgitation following blunt chest trauma. The two patients were diagnosed 13 years and six years, respectively, after the trauma. In both cases, tricuspid valvular insufficiency was caused by anterior leaflet prolapse due to chordal and papillary muscle rupture associated with annular dilatation. Operative repair with implantation of artificial chordae, papillary muscle reinsertion and ring annuloplasty resulted in complete recovery. The need for increased awareness of this lesion in patients suffering blunt chest trauma is emphasized, and the relevant literature reviewed.

Background and aim of the study: The characterization of heart valve prostheses requires regurgitation tests to be conducted in pulsatile flow. Although tests are generally conducted in accordance with hemodynamic conditions of a healthy young man, heart valve implantation is often associated with other pathology, such as atrial fibrillation. To run more realistic trials, four mechanical heart valve prostheses were tested with, and then without, atrial contraction. Methods: The dual activation simulator (DAS) allow simulation of physiologically normal and pathological flows through the mitral valve. The DAS comprises silicon-based cavities, is activated by pumps, and was equipped successively with monoleaflet (Björk-Shiley, Medtronic Hall) and bileaflet (St. Jude Medical, CarboMedics) valves. Each valve (mitral, size 27 mm) was tested under two conditions (with and without atrial contraction) at a mean flow rate of 3 l/min of glycerol/water solution (analog blood viscosity). Results: Leakage volumes were of the same magnitude as the precision of the instruments. Respectively, closing volumes increased from normal conditions to atrial fibrillation from 3.2 to 5.1 ml for Björk-Shiley, from 4.6 to 6.3 ml for Medtronic Hall, from 5 to 6.6 ml for St. Jude Medical, and from 5.2 to 5.4 ml for CarboMedics. The standard deviation was below the precision of measurements (+/- 0.5 ml). Conclusion: Without atrial contraction, the valves seemed to be closed by backward flow only, thus confirming earlier reports. This study showed that different heart valves behave differently in pathological situations with regard to their design; this must be considered when selecting a valve for implantation.

Background and aim of the study: Following clinical experience with the Medtronic Parallel bileaflet mechanical heart valve, considerable interest has been shown in investigating fluid mechanics inside the hinge socket. Most of these studies involved hinges that are recessed into the valve housing, such as the St. Jude Medical (SJM), CarboMedics, Sorin and On-X bileaflet mechanical heart valves. The aim of this study was to investigate the flow fields of a protruded hinge under steady flow conditions, with the occluder in its fully open position. Computational fluid dynamics (CFD) simulation using the Fluent 4.4.7 commercial solver was applied in this investigation. This protruded hinge mechanism for pivoting the occluder is an in-house design from the Cardiovascular Dynamics Laboratory, Nanyang Technological University.

Methods: The Fluent 4.4.7 code was run on a Silicon Graphic Inc. computer (4-CPUx185 MHz) in the CFD simulation. A body-fitted coordinates (BFC) grid was generated to cover the entire valvular flow domain, including the interior of the hinge and leaflet. Clearance between the leaflet and pivot housing was 50-70 microm. In the vicinity of the protruded hinge, mesh cells were small compared with hinge dimensions. A power law distribution of grid points was applied to optimize the number of cells used to cluster the entire flow field. The overall computational flow domain of the valve channel, including the floating leaflet and immersed hinge, was approximately 170,000 cells in total. Inside the hinge socket, approximately 10,000 cells were generated. A comparative model with recessed hinge that resembled the SJM valve hinge design was modeled. Due to geometric difficulties, an unstructured grid scheme was applied. Great attention was focused within the hinge pocket, in particular to the clearance between the hinge pivot and leaflet. A total of 2 million cells was generated for the whole computational flow domain. Results: Under steady flow conditions, with the leaflet fixed in an open position, the protruded hinge design yielded a pair of small vortices that formed behind the stoppers. A low-magnitude velocity was observed inside the hinge clearance. Vortices developed behind the protruded stopper. Migrating flow was noted beneath the leaflet clearance as a result of pressure difference across the leaflet. For the recessed hinge design, reverse flow dominated the inside of the hinge socket, and developed into a pair of vortices at high Reynolds number. Conclusion: The protruded hinge mechanism was designed to expose the overall hinge region to the mainstream flow for a positive washing effect. Flow in this protruded hinge design is, in general, found to be three-dimensional. Initial results under steady flow conditions showed low laminar and turbulent shear stress, while the hinge clearance was well washed.

Background and aim of study: Strong interactions are believed to exist between the pulsating valvular flow and the valve leaflet motions. Hinge position, indicated by d/W (d = distance between the two axes of the hinge pivots; W = width of the testing section in the middle plane), plays a critical role in MHV performance. An optimized hinge position for a bileaflet heart valve can be identified as a design criterion for better valve performance. Methods: A two-dimensional (2-D) digital particle image velocimetry (DPIV) system was used to map the transient flow field of a simplified 2-D model of a bileaflet heart valve with a hydraulic diameter enlarged three-fold under pressure waveforms which was expanded based on Womersley number and Euler number considerations. Six different hinge positions were investigated. Results: At extreme hinge positions (d/W <0.2 or d/W >0.3), large-scale and long-duration stagnation of flow was found in the central orifice, and instability and highly disturbed flow was noted in plots of velocity vectors. Conclusion: The transient flow pattern in the vicinity of the valve was greatly affected by the hinge position of moving leaflets. An optimum d/W in the range 0.2-0.3 yielded good velocity field and opening and closing behaviors.

Background and aim of the study: The recent clinical history and experimental studies of the Medtronic Parallel (MP) valve suggest that bileaflet valve leakage flow is a primary initiator of thrombosis. These studies investigated the effects of physiologic leakage flow through a MP valve on various markers of blood damage. Methods: A centrifugal pump was used to drive whole, human blood anticoagulated with PPACK through a circuit containing a MP 27 mm valve in the closed position (experimental runs) or a MP 27 mm valve in the open position (control runs). Samples were taken at set time intervals after the start of the pump. These samples were analyzed by cell counting, flow cytometry, and ELISA. Results: Cell counts remained relatively constant in both the experimental and control runs. Increases in plasma hemoglobin concentration and the percentage of glycophorin A-positive fragments in the cell population were not significant in either the experimental or the control runs. Plasma platelet factor 4 activity and the percentage of the CD41-positive population which was positive for annexin V increased significantly (p <0.05) in the experimental runs compared with the control runs. Conclusion: The results indicate that bileaflet valve leakage flow causes significant platelet disruption, that erythrocytes are more resistant to disruption by leakage flow than platelets and granulocytes, and that annexin V binding to platelets and plasma platelet factor 4 activity are more sensitive markers of leakage induced blood damage than plasma hemoglobin concentration.

Background and aim of the study: Aprotinin is effective in promoting hemostasis, notably in cardiac surgery with cardiopulmonary bypass. Its efficacy has been shown in coronary bypass graft operations. However, few reports exist of aprotinin use in valve operations, and in those studies only the full dose was used. Thus, our aim was to evaluate the effects of low-dose aprotinin in patients undergoing heart valve reoperation. Methods: Eighteen patients having reoperative valve surgery received 10(6) KIU aprotinin after induction of anesthesia, and a further 10(6) KIU in the pump prime. A group of 18 similar patients who were operated on but did not receive aprotinin were used as controls. Results: A significant reduction in postoperative blood loss (approximately 470 ml) occurred in patients receiving aprotinin. These patients also presented less postoperative bleeding than untreated patients in 70.4% of cases. No adverse effects of the drug were noted, except for one case of allergic reaction. Conclusion: The systematic use of low-dose aprotinin should be considered in valve reoperation, except in cases of re-exposure to the drug, or allergic reaction.

The modified Duromedics-Tekna bileaflet pyrolitic carbon mechanical prosthesis was reintroduced by Baxter in 1990. This report details the first case of sudden leaflet fracture of a Tekna mitral valve five years after implantation, which was managed successfully by replacement with a St. Jude Medical mechanical prosthesis. The fracture had occurred transversely, with the fragments embolizing to the terminal aortic bifurcation and the left common femoral artery. These were localized by computed tomography and removed two days after valve replacement.

Background and aim of the study: Approximately 82,000 Björk-Shiley convexo-concave (BSCC) 60 degree prosthetic heart valves were implanted in patients worldwide between 1979 and 1986. Outlet strut fractures (OSF) of some of the valves were first reported shortly after their introduction. Here, the determinants of OSF are examined, and the between-country variation and long-term risk are assessed. Methods: Cohorts of patients in the UK, Netherlands and USA with 15,770 BSCC 60 degree heart valves were followed up to 18 years for the occurrence of OSF. Results: Crude rates of OSF were highest in the UK (0.18% per year), intermediate in the Netherlands (0.13%), and lowest in the USA (0.06%), although risk factor adjustment reduced the inter-country differences. Furthermore, in the UK and Netherlands, OSF rates (particularly for mitral valves) declined with time since implantation, and between-country differences were considerably diminished 10 or more years post implantation. The risk of OSF decreased steadily with advancing patient age. Fracture rates were lower among women than men, and also varied significantly with valve size and position and OSF status of other valves in the same shoporder. Conclusion: This long-term follow up of BSCC 60 degree heart valve patients indicates that risk factors for valve fracture are generally similar in the UK, Netherlands and USA. It also identifies a strong association between fracture risk and age, newly reveals gender-related differences, and shows that the risk of valve fracture persisted, albeit at a reduced rate, into the 1990s.

Background and aim of the study: Aortic valve replacement can result in patient-valve mismatch and attenuated left ventricular remodeling. Using CarboMedics mechanical valves, we examined if the supraannular Top Hat prosthesis provided a size advantage over the intraannular valve. Methods: Seventeen patients with aortic stenosis and aortic root < or = 23 mm were randomized to receive a CarboMedics supraannular Top Hat valve (n = 7) or an intraannular valve (n = 10). Doppler echocardiography was performed preoperatively, and after three months. Results: There was no difference in aortic annulus size, but mean prosthesis size was significantly larger in the Top Hat group than in the intraannular group (25.00 mm versus 21.60 mm); the mean size improvement for Top Hat patients was 3.14 mm. After three months, all patients had excellent functional improvement and low transvalvular pressure gradients, with slightly higher effective valve opening area in the Top Hat group. Conclusion: The supraannular Top Hat valve provides an advantage of one to two sizes over the intraannular valve, and improves the effective valve opening area. Both valves offer favorable hemodynamic performance and functional improvement.

Background and aim of the study: The clinical evaluation and comparison of St. Jude Medical (SJM) and CarboMedics (CM) prosthetic heart valves implanted between 1988 and 1997 is presented. Methods: In total, 648 SJM valves were implanted in 641 patients, and 601 CM valves in 591 patients. There were 684 mitral valve replacements, 256 aortic valve replacements, 252 mitral and aortic (double) valve replacements, 16 triple valve replacements, and 41 other tricuspid-related valve replacements. Total follow up was 98%. The overall incidence of valve-related events was compared before and after establishment of a 'valve clinic' in 1993. Results: The overall hospital mortality was 3.4%; late mortality was 8.2%. The five- and ten-year survival for all patients was 92.1% and 86.2%, respectively. There were 31 episodes of thromboembolism in 27 patients (including valve thrombosis in three), 21 episodes of bleeding events in 20 patients, and 18 re-replacements of implanted valves. No structural valve deterioration was observed. Freedom from thromboembolism was 97.8% at five years and 96.3% at ten years; freedom from bleeding episodes was 98.1% and 97.6%, respectively. In terms of hospital and late mortality, and incidence of thromboembolism, hemorrhagic episodes and structural valve failure, no statistically significant differences were found between the SJM and CarboMedics patient groups. Freedom from thromboembolism was 96.7% at five years before initiation of an intensive follow up program, and 99.0% thereafter (p = 0.031). In contrast, freedom from bleeding episodes fell from 99.3% to 96.1% during the same time period (p = 0.0004). Conclusion: Both the SJM and CM prosthetic heart valves performed well in our study, and no discernible differences in clinical performance of the two valves were detected. The intensive follow up program resulted in a reduced incidence of thromboembolism, but an increased number of bleeding complications. An optimum anticoagulation regimen to manage these two conflicting problems has yet to be elucidated.

Background and aim of the study: The CarboMedics bileaflet prosthetic heart valve was first implanted as part of a prospective clinical study at the authors' institution in November 1987. The patient cohort included was part of a multicenter trial set up by the manufacturer for an FDA application. The present report details findings over a 12-year period, with a continuous follow up on this patient cohort. Methods: Between November 1987 and August 1990, 132 patients (68 males, 64 females; median age 56 years; range 12-74 years) received a CarboMedics heart valve prosthesis. All patients were included in the study, whether surgery was elective or emergency, first time or reoperation. There were 69 aortic, 49 mitral and 12 double (aortic + mitral) valve replacements. Two patients had isolated tricuspid valve replacement. Concomitant surgery was performed in 15 patients. Anticoagulation with warfarin was started on postoperative day 1. After discharge, patients were examined regularly as outpatients for up to five years. Subsequent follow up was obtained prospectively by questionnaires to the patients' general practitioner, or by telephone calls. Actuarial estimates of survival and freedom from morbid events were calculated using the Kaplan-Meier method; 95% confidence limits for the distribution function were calculated according to the Greenwood formula. Results: Complete follow up information was available for 94% of the patients; total follow up was 1,014.3 patient-years (pt-yr). Actuarial survival at 12 years was 62 +/- 0.5% overall (61 +/- 6.5% for aortic; 66 +/- 7.5% for mitral; 65 +/- 14.0% for double valve replacements). Actuarial rates of freedom from complications were: valve thrombosis 100%, embolism 92 +/- 2.8%, and anticoagulant-related bleeding 77 +/- 5.6%. The linearized rates per 100 pt-yr were: embolism 0.89 (aortic 0.74, mitral 1.30); anticoagulant-related bleeding 2.56; paravalvular leakage overall 0.20 (aortic 0.37); prosthetic valve endocarditis overall 0.20 (aortic 0.37). There was no hemolysis, prosthetic valve dysfunction or structural deterioration. Conclusion: Over a 12-year time frame, the CarboMedics prosthetic heart valve has proven to be a highly reliable device with no structural failures, and a low incidence of valve-related complications

Background and aim of the study: The study aim was to examine prospectively the clinical performance and durability of the Medtronic Mosaic bioprosthesis, a stented porcine aortic valve that combines improvements in tissue preservation, notably net zero differential pressure fixation of the leaflets, with antimineralization treatment using 2-amino-oleic acid (AOA). Methods: A total of 158 Mosaic valves was implanted; 152 in patients aged over 70 years, and six in patients aged <70 years with contraindications to anticoagulant therapy. Mean age was 73.7 years. All valves were implanted in the supraannular position. Thirty-two patients (20%) required concomitant procedures, including coronary revascularization, ascending aorta replacement and/or mitral annuloplasty. Postoperative anticoagulation (heparin) was prescribed for ten days, followed by antiplatelet therapy. No long-term oral anticoagulants were prescribed, except in some patients with atrial fibrillation. The follow up included routine clinical and blood work-up, and echocardiography at six months and one year after surgery. Results: There were seven early (0-30 days) and five late deaths (>30 days). One death was caused by a hemorrhagic stroke at three months in a patient without anticoagulant or antiplatelet therapy. No thromboembolic complications or structural valve deterioration were observed during follow up. At two years, freedom from endocarditis and reoperation was each 99.6%. NYHA class was excellent, with 98% of patients in class I or II at one year. Patient survival was 92% at two years. Hemodynamically, the valve was performing well, with mean systolic gradients of 13.6, 13.2, 12.6 and 9.6 mmHg for the 21, 23, 25 and 27 mm valves, respectively. There was no evidence of structural valve deterioration. Conclusion: Long-term evaluations are mandatory to confirm the durability of any new bioprosthetic valve. Satisfactory early clinical and hemodynamic results with the new Mosaic bioprosthesis warrant its continued implantation in the aortic position for patients over the age of 70 years.

Background and aim of the study: Rest, and especially exercise, hemodynamics are valuable determinants to assess outcome of the Ross procedure. In this study, the degree of insufficiency and pressure gradients at rest across the autograft and homograft, as well as the pressure gradients at exercise, were measured. Methods: Among 115 patients operated on between February 1990 and February 1999, 67 were evaluated echocardiographically at rest and moderate exercise. The mean patient age at subcoronary implantation was 52 +/- 13 years. The mean interval between surgery and investigation was 27.3 +/- 17.4 months. The exercise level was 100 W (n = 47), 75 W (n = 14) or 50 W (n = 6). Results: Fifty-two patients had no or trace aortic insufficiency, 23 were grade I/IV, and two were grade II/IV. Pulmonary insufficiency was graded as none (n = 45), mild (n = 21), and moderate (n = 1). Heart rate increased from 70 +/- 12 beats/min at rest to 108 +/- 19 beats/min at exercise. The maximal pressure gradient across the autograft increased from 6.1 +/- 2.3 mmHg at rest to 8.7 +/- 4.1 mmHg at exercise. The maximal pressure gradient across the homograft increased from 11.8 +/- 5.3 mmHg at rest to 17.7 +/- 8.2 mmHg at exercise. A pressure gradient across the homograft >25 mmHg was measured in 13 patients. Conclusion: In most patients, hemodynamics at rest and moderate exercise at an average of more than two years after the Ross procedure were excellent. Some homografts developed pressure gradients at exercise; this finding will form the target of future surgical and scientific investigations.

Background and aim of the study: The study aim was to examine the long-term outcome (nine years) of mitral balloon valvotomy in pregnant patients with severe mitral stenosis. Methods: Twenty-three patients with severe, symptomatic (NYHA class III/IV) mitral stenosis underwent mitral balloon valvotomy using an Inoue balloon technique during the second trimester of their pregnancy; mean follow up in 19 patients was 5.1 +/- 2.8 years (range: 1 to 9 years). Results: The procedure was successful in all patients. Immediately after valvotomy, the Doppler-derived mitral valve area increased from 0.90 +/- 0.18 to 1.97 +/- 0.36 cm2 (p <0.0001), and the transmitral mean gradient decreased from 15.7 +/- 4.7 to 5.5 +/- 1.6 mmHg (p <0.0001). Four patients had mild worsening of mitral regurgitation, and six developed insignificant interatrial communication immediately after valvotomy. There was no other morbidity or mortality. Patients showed a significant improvement in mean NYHA class, from 3.0 +/- 0.1 to 1.0 +/- 0.02 (p <0.001). Twenty-two patients had normal deliveries; one cesarean section in week 36 resulted in stillbirth. No developmental abnormalities were seen in the babies. At long-term follow up of mothers, the mitral valve area was 1.8 +/- 0.52 cm2; restenosis developed in three patients (16%). One baby died at one week from sudden infant death syndrome, and one at eight months, from pneumonia. All other children showed normal growth, development and speech for their age. Conclusion: Mitral balloon valvotomy using the Inoue balloon technique can provide satisfactory immediate relief and long-term outcome in pregnant patients with severe mitral stenosis

Background: The Björk-Shiley convexo-concave (BSCC) prosthetic valve was introduced in 1979. Between 1979 and 1986, approximately 86,000 BSCC valves were implanted. By December 31, 1994, 564 complete strut fractures had been reported to the manufacture. We experienced a case of an outlet strut fracture and investigated the risk of BSCC prosthetic valve fractures in Japan. Methods and results: To investigate the risk factor of a strut fracture in Japan, we investigated published cases of strut fractures. Between 1979 and 1986, 2021 BSCC valves were implanted in Japan. By January 31, 2000, 11 complete strut fractures of 60-degree BSCC valves including our case had occurred. The patients were eight males and three females. The average age at valve replacement was 42.4+/-8.1 years, and nine of eleven (81.8%) were patients < 50 years-old. The average age of the patients when the BSCC valve fractured was 47.7+/-6.4 years, and eight of eleven (72.7%) were patients <= 50 years old. All patients were implanted in the mitral position. The sizes of the BSCC valve were 27 mm (n=5) (45.5%), 29 mm (n=3) (27.2%), and 31 mm (n=3) (27.2%). Four patients died and seven patients survived. Conclusions: Although only 11 BSCC valve struts fractured and statistical analysis could not be performed, our findings suggest that the high risk group for a strut fracture in Japan is young male patients with a mitral valve, >= 27 mm in size with BSCC models manufactured before March 1982. When following-up patients with BSCC models manufactured before March 1982, the possibility of a strut fracture in all BSCC valve sizes should be kept in mind.