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PubMedDate not supplied

[Maximum flow velocity in the normally functioning Björk-Shiley mitral prosthesis].

The heart valve prosthesis, even with normal function produce a functional obstruction to the blood flow increasing its maximal velocity. With pulsed wave Doppler technique we measured the maximal velocity in 12 patients with normally functioning Bjork-Shiley mitral prosthesis, (group I), comparing the results with those obtained in 12 healthy persons (group II). The maximal velocity of group I was significantly higher than that of group II (p less than 0.001) and higher than the values so far reported in the literature. In 5 patients of group I the maximal velocity was above 2.6 m/sec, which is the upper limit that our Doppler unit is able to register. We conclude that the maximal velocity of blood flow through some Bjork-Shiley mitral valves with normal function may be higher than those reported in the literature. Therefore the pulsed wave Doppler technique has limited application in the evaluation of transprothetic flow.

Adolescent↗
PubMed1999

Distortion of the stentless porcine valve induces accelerated leaflet fibrosis and calcification in juvenile sheep.

BACKGROUND AND AIM OF THE STUDY: Stent mounting of a porcine aortic valve induces loss of mobility and reduces the effective orifice area. Any stentless design conserves the flexibility of the valvular apparatus, but unfortunately, these valves require a more elaborate implantation technique which is considered a major drawback by many surgeons. In an attempt to see if the insertion of the Toronto SPV stentless valve could be made easier, we altered the configuration by lowering the profile at the depth of both coronary sinuses. Theoretically, this could enable insertion of the valve by a single suture layer under the two coronary ostia, in addition to some fixation points at the commissures. METHODS: Two modified 20 mm Toronto SPV valves were tested in vitro for hydrodynamics in a computer-controlled pulse duplicator system and compared with two standard 20 mm valves. Animal implant studies using three standard versus three modified valves (21, 23 and 25 mm) were conducted in juvenile sheep for durability and biocompatibility over a period of three months. RESULTS: The standard Toronto SPV valve provided excellent hemodynamics. The altered configuration performed less optimally during hydrodynamic testing with increased transvalvular gradients. In animal implant studies, cusps adjacent to all reduced-height sinuses showed markedly accelerated fibrosis and substantial calcification, in contrast to only mild fibrosis on the inflow aspects of the standard leaflets. CONCLUSIONS: The more pronounced the deformation of the stentless valve, the faster the calcification of the leaflets adjacent to the distorted sinuses. As both valves types were prepared using an identical preservation technique, the role of loss of mobility in leading to early failure is clearly demonstrated. These findings also underline the extreme importance of correct implantation technique for all stentless valves in order to prevent degeneration.

Animals↗
PubMedDate not supplied

The relationship between the mitral annulus and left ventricular outflow tract.

Mitral annular inflexibility due to rigid prostheses (ring or valve) has long been considered to contribute to the mechanism of dynamic left ventricular outflow tract (LVOT) obstruction after mitral repair or replacement. In clarifying the geometric relationship between LVOT orifice and mitral valve annulus (MVA) in eight normal subjects, the authors have endeavored to show how that a rigid mitral prosthesis might obstruct the LVOT based on the assumption that any rigid prosthesis necessarily follows the motion of the posterior half of the MVA (MVApost) in the course of every heart beat. During systole, the relationship between the MVApost and the approximated plane of the LVOT orifice was constant. However, with the respect to the relationship between the LVOT orifice and the approximated plane of the MVApost (PI-MVApost), the intersection between the two shifted toward the apex during systole. Assuming the prosthesis is aligned on the MVApost with the same orientation as the PI-MvApost, this shift implies a reduction in the effective size of the LVOT orifice due to the prosthesis. The calculated obstruction rate was 24.9% (0 ms), 30.9% (100 ms), 35.5% (200 ms), and 45.4% (300 ms). These results indicate the importance of maintaining the flexibility of the MVA after mitral valve surgery.

Adult↗
PubMed2004

Heart valve tissue engineering.

Valvular heart disease is a significant cause of morbidity and mortality world-wide. Classical replacement surgery involves the implantation of mechanical valves or biological valves (xeno- or homografts). Tissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart surgery. Various approaches have been developed differing either in the choice of scaffold (synthetic biodegradable polymers, decellularised xeno- or homografts) or cell source for the production of living tissue (vascular derived cells, bone marrow cells or progenitor cells from the peripheral blood). The use of autologous bone marrow cells in combination with synthetic biodegradable scaffolds bears advantages over other tissue engineering approaches: it is safe, it leads to complete autologous prostheses and the cells are more easily obtained in the clinical routine. Even though we demonstrated the feasibility to construct living functional tissue engineered heart valves from human bone marrow cells, so far their general potential to differentiate into non-hematopoietic cell lineages is not fully exploited for tissue engineering applications.

Absorbable Implants↗
PubMed2003

Risk factors for atherosclerosis and the degeneration of pericardial valves after aortic valve replacement.

BACKGROUND: Recent studies have demonstrated the influence of atherosclerotic risk factors on the progression of aortic stenosis. We hypothesized that risk factors for atherosclerosis might also be involved in the degeneration of pericardial heart valves and might lead to reoperation as a result of structural valve failure, especially in younger patients with high degeneration rates. METHODS: In 1984 and 1985, 161 patients (74% male; mean age, 54.4 +/- 1.0 years; age range, 17-76 years; median age, 56.5 years) survived isolated aortic (n = 137) or combined aortic and mitral (n = 25) valve replacement with a Hancock extracorporeal pericardial valve. Of these patients, 90 (56%) had reoperations as a result of tissue failure of the aortic valve 5.6 +/- 0.25 years postoperatively. RESULTS: The patient group was split in half at the median age. In patients aged 57 years or younger, diabetes mellitus, female sex, cigarette smoking, and high cholesterol and triglyceride levels were associated with accelerated valve failure. In a multivariate model sex (female, P =.001), smoking (P =.001), diabetes mellitus (P =.020), and cholesterol levels (P =.011) are risk factors for reoperation. Patients without risk factors had reoperation after a mean of 9.25 +/- 0.88 years compared with 4.05 +/- 0.43 years (P =.0002) in patients with 2 or 3 risk factors. CONCLUSIONS: Risk factors of atherosclerosis might play a substantial role in the degeneration of aortic bioprosthetic valves. Lowering of serum lipid levels, smoking cessation, therapy for diabetes, and careful patient selection could be new strategies to postpone degeneration. Younger patients could then possibly benefit from the advantages of bioprostheses.

Adolescent↗
PubMedDate not supplied

Reduction of mitral regurgitation using the Coapsys device: a novel ex vivo method using excised recipients' hearts.

The purpose of this study was to evaluate the ex vivo effects of the Coapsys device upon functional mitral regurgitation (MR) in human hearts. We used seven excised hearts from patients who underwent cardiac transplantation. All patients had functional MR of grade 2 or greater associated with dilated (n = 3) or ischemic (n = 4) cardiomyopathy. After the aortic valve was removed, the left ventricle was pressurized from the aorta with saline at a constant pressure. The degree of MR was then subjectively graded from the opened left atrium (from 0 to 4). The last three studies included volumetric measurements of MR. By tightening the device, the mean MR grade was reduced from 3.3 +/- 0.8 to 1.1 +/- 0.4 (p = 0.0002). In the quantitative analysis, mean regurgitation volume was reduced from 1,108 +/- 1,134 ml/min to 236 +/- 89 ml/min (p = not significant). The mitral annular septal-lateral dimension decreased from 2.0 +/- 0.3 cm to 1.6 +/- 0.5 (p = 0.043). The Coapsys device reduced functional MR in the ex vivo study using excised dilated hearts.

Cardiomyopathy, Dilated↗
PubMed2005

PCR detection of bacteria on cardiac valves of patients with treated bacterial endocarditis.

We used broad-range PCR amplification and sequencing to detect and identify bacterial DNA in 156 valves of patients treated for infective endocarditis (IE). Bacterial DNA was found more frequently in patients who underwent valve replacement while on antibiotic treatment for IE (60%) than in patients who had completed antibiotic treatment for IE (37%; P = 0.02). We found specific bacterial DNA in valves removed from 11 of 30 patients who had completed antibiotic treatment for IE. Six had no histological evidence of IE. The presence of DNA was significantly correlated with the presence of histologic lesions (P = 0.001) and with the presence of bacteria detected by Gram staining (P < 0.001). Bartonella and streptococci were detected for much longer after antibiotic treatment by PCR than other species (P = 0.047 and 0.04, respectively), and coagulase-negative staphylococci were detected for much shorter periods (P = 0.02). The finding that bacterial DNA was more likely to be detected in valves of patients with active IE than in patients who had completed antibiotic treatment for IE shows that bacterial DNA is cleared slowly. There was no significant correlation between the duration of antibiotic therapy and the presence of bacterial DNA in valves. Since the persistence of bacterial DNA in valves does not necessarily indicate the persistence of viable bacteria, the detection of bacterial DNA in valves from IE patients should be interpreted with caution, in particular in those patients with a past history of treated IE.

Adult↗
PubMed1999

Anticoagulation after artificial valve replacement with or without atrial fibrillation: how much is really needed?

Insertion of a mechanical artificial heart valve is an absolute indication for the use of lifelong oral anticoagulation, irrespective the presence or absence of atrial fibrillation. Depending on the type and position of the artificial valve the optimal International Normalized Ratio (INR) for these patients is between 2.5 and 4.5, although more prospective studies on the optimal range of oral anticoagulation are necessary. Addition of low dose antiplatelet therapy may further decrease the rate of thromboembolism, but also here more studies are needed. Patients with a bioprosthesis need only oral anticoagulation for the first three months following surgery in the absence of an indication for anticoagulation for other conditions. Atrial fibrillation is often seen in patients with artificial heart valves. Stroke prevention can be instituted by the mandatory oral anticoagulant therapy. The presence of atrial fibrillation and the use of oral anticoagulation prior to heart valve surgery support the indication for the insertion of a mechanical artificial heart valve. However, relative contraindications to oral anticoagulation and the presence of sinus rhythm may favor the use of a bioprosthesis.

Anticoagulants↗
PubMed2003

The surgical approach to infective endocarditis: 10 year experience.

BACKGROUND: About 40% of patients with infective endocarditis will require surgical treatment. The guidelines for such treatment were formulated by the American College of Cardiology and American Heart Association in 1998. OBJECTIVES: To examine our experience with surgical treatment of infective endocarditis in light of these guidelines. METHODS: Surgery was performed in 59 patients with infective endocarditis between 1990 and 1999. The patients' mean age was 48 years (range 13-80). The indications for surgery were hemodynamic instability, uncontrolled infection, and peripheral embolic events. The surgical treatment was based on elimination of infection foci and correction of the hemodynamic derangement. These objectives were met with valve replacement in the majority of patients. Whenever conservative surgery was possible, resection of vegetation and subsequent valve repair were performed and the native valve was preserved. RESULTS: Six patients (10%) died perioperatively from overwhelming sepsis (n = 3), low cardiac output (n = 2) and multiogran failure (n = 1). The mean hospital stay was 15.6 days. Of 59 patients, 47 (80%) underwent valve replacement and in 11 (19%) the surgical treatment was based on valve repair. After 1 year of follow-up there was no re-infection. CONCLUSION: The new guidelines for surgical treatment of infective endocarditis allow better selection of patients and timing of surgery for this aggressive disease, which consequently decreases the mortality rate. Valve repair is feasible and is preferred whenever possible. According to the new guidelines, patients with neurologic deficit in our series would not have been operated upon, potentially decreasing the operative mortality to 7%.

Adolescent↗
PubMed2006

Early postoperative anticoagulation after mechanical valve replacement: a Canadian survey.

BACKGROUND AND AIM OF THE STUDY: The optimal approach to anticoagulation during the early postoperative period after mechanical valve replacement, by which early thromboembolism is prevented without bleeding complications, is not yet known. The study aim was to examine the practice patterns of Canadian cardiac surgeons with regard to early postoperative anticoagulation after mechanical valve implantation. METHODS: A questionnaire was sent to 100 Canadian cardiac surgeons in July 2004, and 57 responses were received. Data were collected regarding the approaches to early postoperative anticoagulation following uncomplicated isolated mechanical aortic valve replacement (AVR) and mitral valve replacement (MVR). RESULTS: Heparin was administered routinely after AVR and MVR by 63% and 68% of surgeons, respectively. This was most commonly initiated on postoperative day (POD) 1, and given either subcutaneously (AVR, 28%; MVR, 25%) or intravenously (AVR, 33%; MVR, 42%). Alternatively, low-molecular-weight heparin was used by 21% and 23% of surgeons after AVR and MVR, respectively. Oral warfarin was usually started on POD 1 (72% and 68%, respectively), with 40% prescribing an initial dose between 2.5 and 5.0 mg, and 51% administering between 5.1 and 7.5 mg. When heparin was not used, oral anticoagulation was more often administered earlier (AVR, p = 0.003; MVR, p = 0.006), but not at higher doses (AVR, p = 0.07; MVR, p = 0.2). Following surgery, aspirin was prescribed by 61% and 65% of surgeons after AVR and MVR, respectively. CONCLUSION: The study results highlighted a significant variability in the management of early postoperative anticoagulation after mechanical valve implantation. The clinical impact of these findings is unknown, and can only be assessed through a prospective trial.

Anticoagulants↗
PubMed2006

Left ventricular remodeling impacts the function of the Quattro stentless mitral valve bioprosthesis (a 4-year experience).

OBJECTIVE: The St Jude Quattro stentless mitral valve prosthesis (QMV) is sutured to the mitral annulus and the papillary muscle heads, thereby preserving the subvalvular apparatus. After mitral valve replacement, remodeling of the left ventricle is often observed, causing a dilated ventricle to shrink in diameter. It was our objective to assess these changes in left ventricular (LV) geometry and evaluate its effects on the function of the QMV. METHODS: From September 1997 to October 2000, 24 patients received QMV at our institution. The patients were followed up at yearly intervals (mean 4.1 +/- 2.2 years). All pre- and postoperative echocardiograms were evaluated, with attention focused on the subvalvular apparatus, leaflet morphology, and occurrence of late mitral regurgitation. In addition, all clinical outcomes and valve-related complications were recorded. RESULTS: Forty-one percent of patients (10/24) developed late mitral regurgitation (mild, n = 5; moderate, n = 5). The site of regurgitation was located at the 2 commissures in all cases. In 8 patients, changes in LV diameter had occurred. The point of leaflet coaptation had shifted away from the annulus in 4 patients. The overall mortality was 12.3%, and the postoperative stroke rate was 12.3%. CONCLUSIONS: Midterm changes in LV geometry seem to affect the competence of the QMV. Predicting these changes and subsequently adapting the sizing procedure remain a challenging task. The high rate of late valve incompetence and poor clinical outcomes has prompted us to discontinue recruitment of patients for this trial.

Bioprosthesis↗