Infective endocarditis (IE) due to Gram-negative bacteria is a rare occurrence, with a relative frequency of less than 10% compared to that caused by Gram-positive bacteria. Herein is presented the fatal case of a 66-year-old man who had undergone mechanical aortic valve replacement 10 years previously, and developed aortic valve IE after sepsis with Pasteurella multocida caused by a cat bite at the left medial ankle. In addition, the patient suffered five months later from mitral and aortic valve endocarditis caused by Pseudomonas aeruginosa. Recurrent surgical therapy was mandatory. This unique case of recurrent Gram-negative IE shows that the condition must still be regarded as complex and often fatal, despite adequate medical and surgical treatment.

Background and aim of the study: Tissue thickness plays an important role in oxygen and nutrient transport and supply of tissue-engineered aortic valves. The study aim was to investigate the effect of tissue thickness and thickness variation on oxygen diffusion in a three-dimensional (3D) aortic valve leaflet model. Methods: Replicas of fresh porcine aortic valve cusps were cast using synthetic rubber, and the corresponding thickness profiles measured using contacting profilometry. Subsequently, the profiles were used for 3D oxygen diffusion modeling. Histological characterization of the trilaminar structure for the valve tissue was carried out to determine the ratios of each individual layer to the total tissue thickness. Computational simulations were carried out based on the native aortic cusp geometry obtained by the 3D thickness profiles, employing the finite difference numerical approach. Results: Excellent agreement in predicted oxygen pressure was achieved between the numerical solution, under both steady-state and transient conditions, and the analytical solution of the steady-state case. Oxygen distribution in the aortic leaflet model was predicted and compared to that of the two-dimensional (along the radial direction and cusp thickness) and one-dimensional (along the cusp thickness) models. Finally, the variation of predicted hypoxic areas with increasing mean cusp thickness was investigated. Conclusion: The study results showed that the finite difference method can provide an accurate estimate of oxygen distribution within the leaflet. They also showed that both tissue thickness and thickness variation determined the minimum oxygen tension in the center of the leaflet, indicating that a 3D model is necessary in order to accurately predict oxygen distribution within the native leaflet.

Background and aim of the study: Valvular calcification is an active, cell-mediated process that results in significant morbidity and mortality. In standard culture, valvular interstitial cells (VICs) elicit significant calcification as a result of myofibroblast activation, and this limits their use in characterization studies. The study aim was to identify culturing substrates that would suppress atypical VIC calcification, and to investigate culture substrates representing a more physiological system. Methods: Several culture platforms were selected to compare and contrast the influence of biochemical and mechanical properties on VIC calcification. Substrates investigated included: tissue culture polystyrene (TCPS), TCPS coated with either fibronectin or fibrin, and an elastic poly(ethylene glycol) (PEG) hydrogel, also with fibronectin or fibrin coupled to the surface. Experiments were repeated with profibrotic growth factor transforming growth factor-beta 1 (TGF-beta1). VIC calcification was characterized by calcific nodule formation, alkaline phosphatase activity and calcium accumulation. Gene and protein expression of alpha smooth muscle actin (aSMA) and core binding factor-1 (CBFa-1) were analyzed with qRT-PCR and immunostaining. Results: Unmodified TCPS substrates had an innate ability to promote the markers of calcification studied. The addition of TGF-beta1 enhanced levels of all osteoblastic markers studied. When TCPS surfaces were modified with fibronectin, all markers for calcification were repressed, but alphaSMA - a marker for myofibroblastic activity was unchanged. Meanwhile, fibrin-modified TCPS surfaces enhanced calcification over unmodified TCPS substrates. On soft PEG hydrogels, all markers for calcification were repressed, regardless of the surface chemistry, while alphaSMA expression remained unaffected. Conclusion: Collectively, VIC properties are highly linked to the culture microenvironment. Both, the biochemical and mechanical environment of tissue culture has an effect on the spontaneous calcification of VICs, and may also have a profound effect on their molecular properties, as related to an understanding of the disease process in vivo.

Background and aim of the study: One approach in tissue-engineering involves the implantation of decellularized, xenogenic scaffolds, with the expectation of repopulation in vivo. However, a major limitation of this method is the propensity to induce a strong immune host response. The study aim was to mitigate this immunogenicity by employing a crosslinking treatment with genipin. Methods: Porcine matrices were prepared using a detergent-enzymatic treatment and fixed in 0.01% or 0.001% aqueous genipin. The mechanical properties of the matrices were monitored by tensile strength testing. The survival of chicken fibroblasts was used to determine cell-friendliness of the matrices. Non-fixed, decellularized biological scaffolds (n = 3) were implanted in a sheep model and compared to an equal number of genipin-fixed scaffolds (n = 6). Matrices implanted in the pulmonary position were explanted after six weeks and examined using light and transmission electron microscopy. The antibody reaction against porcine tissue in sheep serum was also determined. Results: Statistically significant differences were found between non-fixed leaflets, 0.001% genipin-and 0.6% glutaraldehyde (GA)-fixed leaflets for work to maximum load (non-fixed 0.00646 J; genipin-fixed 0.00509 J; GA-fixed 0.00543 J) and stiffness (non-fixed 9281 N/m; genipin-fixed 16214 N/m; GA-fixed 14401 N/m). Genipin-treated matrices were not cytotoxic. For all concentrations of genipin a high proportion of viable cells was present (79-100%). Low-dose GA (10 microg/ml) showed a distinct cytotoxicity (24.8% viability). At explant, an intense chronic inflammatory response was observed in non-fixed matrices, in contrast to genipin-fixed scaffolds. The sheep serum showed a marked decrease in IgG response in both 0.001% and 0.01% genipin-fixed matrices (IgG 30 and 20, respectively) when compared to non-fixed matrices (IgG 40). aConclusion: Genipin crosslinking of the matrices attenuated, but did not eliminate, the inflammatory host reaction. Whether genipin treatment might extend the durability of xenogenic scaffolds remains to be investigated.

Bioprosthetic valves are generally considered to carry a low risk of valve thrombosis, obviating the need for long-term anticoagulation in most patients. Few reports exist of the diagnostic characteristics and management of bioprosthetic valve thrombosis. Herein is presented a case of critical bioprosthetic mitral valve thrombosis in which successful clinical and hemodynamic resolution was achieved with intravenous thrombolysis. A current review of the bioprosthetic valve thrombosis literature is also presented.

Prosthetic valve dysfunction is a rare but life-threatening condition. A 66-year-old woman presented with shock 15 years after aortic valve replacement with a tilting-disc valve. Imaging demonstrated severe aortic insufficiency and a fixed-open prosthetic valve. Reoperation revealed pannus ingrowth from the aortic aspect, resulting in immobility of the occluder. A bioprosthetic valve was installed and the patient recovered uneventfully. The diagnosis and surgical management of this problem are discussed.

Background and aim of the study: Previous studies have been unable to identify independent valve-related risk factors for the occurrence of renal failure requiring dialysis (RF-D) in patients undergoing valve surgery. The study aim was to determine the incidence and predictors of renal failure in these patients, and to create a model based on these risk factors that could serve as a tool to predict this complication. Methods: Between January 1998 and December 2006, a total of 2,690 consecutive patients (1,546 males, 1,144 females; mean age 64 +/- 15 years) underwent valve or combined valve/coronary artery bypass graft (CABG) surgery at the authors' institution. The main outcome investigated was postoperative RF-D; other postoperative parameters investigated included hospital mortality, major morbidity, length of hospital stay, discharge condition and late survival. Results: RF-D occurred in 70 patients (2.6%). Multivariate analysis revealed preoperative renal failure (creatinine >2.5 mg/dl) (OR = 4.3), endocarditis (OR = 3.0), congestive heart failure (OR = 2.4), reoperation (OR = 2.3), diabetes (OR = 3.1) and cardiopulmonary bypass time >180 min (OR = 1.7) as independent predictors for postoperative RF-D. Hospital mortality among patients with RF-D was 50% (n = 35) compared to a mortality rate of 3.2% (n = 87) in patients without this complication (p <0.001). The long-term survival of discharged patients with RF-D was significantly decreased compared to those without RF-D. A logistic equation which included the coefficients of the regression analysis was generated to calculate an individual patient's risk for the development of renal failure. The predictive accuracy of the model and validation was measured (ROC area under the curve = 0.750). Conclusion: Renal failure requiring dialysis is a well-known complication, particularly in patients undergoing complex valve operations, such as surgery for endocarditis and double-valve procedures. The poor long-term survival of patients with RF-D underlines the need to direct more resources towards the prevention and treatment of this complication in valve surgery patients.

Background and aim of the study: The study aim was to update the authors' experience with aortic valve replacement (AVR) using the ATS mechanical prosthesis in terms of early and long-term outcome in routine practice. Methods: This retrospective analysis was extracted from clinical data available between April 1996 and February 2005, of AVR with the ATS Medical prosthesis in 510 consecutive patients (345 men, 165 women; mean age 62 +/- 12 years), of whom 296 underwent isolated AVR (iAVR). Concomitant surgical procedures included coronary artery bypass grafting (AVR+CABG, n = 47), mitral valve procedure (AVR+MVP, n = 59), ascending aortic replacement (AVR+AAR, n = 74) and other procedures (AVR+Miscellaneous, n = 34). Early and late morbidity/mortality were analyzed for the entire group in case of emergency surgery, preoperative low left ventricular ejection fraction (LVEF <50%) and in elderly people (age > or = 70 years). Results: The overall 30-day mortality was 7.2% (iAVR 4.7%; AVR+CABG 4%; AVR+MVP 8.5%; AVR+AAR 2.9%; AVR+Miscellaneous 14.7%). The five- and nine-year global survival rates were respectively 81.14 +/- 2.4% and 67.02 +/- 10.4%. Long-term survival was lower in case of emergency surgery (p = 0.001), when the preoperative LVEF was <50% (p = 0.03), and when patients were aged > or = 70 years (p = 0.0005). Linearized postoperative valve-related death was 1.1% per patient-year (pt-yr). However, nine years' freedom from valve-related death and valve-related morbidity were not significantly different when the patient age was > or = 70 years. The linearized rate for postoperative thromboembolism complication was 0.4% per pt-yr, and that for postoperative bleeding complication 0.63% per pt-yr. There were two perivalvular leaks (0.05%/pt-yr). Neither valve thrombosis, structural dysfunction nor endocarditis were observed. Conclusion: The findings of this retrospective study point to a globally very good performance of the ATS valve, and essentially similar to previously reported results with these and other available mechanical valves.

Background and aim of the study: Previously, surgery hypertrophic obstructive cardiomyopathy (HOCM) has consisted primarily of septal myectomy and/or resection of the anterior mitral leaflet with low-profile valve replacement. However, recent studies have shown that the anterior papillary muscle and chordal fan can contribute to obstruction, and also that significant mitral regurgitation (MR) may be encountered. Hence, a surgical procedure was devised to address all components of this disorder. Methods: A 37-year-old man had a history of heart murmur and NYHA class IV symptoms, despite beta-blocker therapy. Echocardiography showed severe septal hypertrophy, systolic anterior motion (SAM) of the mitral valve, severe MR and a 185 mmHg resting outflow tract gradient. At surgery, the anterior papillary muscle was found to be medially displaced and contributing to outflow obstruction. The anterior papillary muscle and chordae were resected, a 'traditional' septal myectomy was performed, and a full annuloplasty ring placed. The mitral valve was repaired by connecting the left aspect of the leaflets to the posterior papillary muscles, using Gore-Tex artificial chords. Results: The patient recovered uneventfully. Interval echocardiography at one year showed a negligible outflow gradient, relief of SAM and mild residual MR. The patient currently is active, essentially asymptomatic, and not receiving any medical therapy. Conclusion: Previous approaches to HOCM have been limited by a small incidence of recurrent outflow gradients, pacemaker requirement, persistent MR or complications of the prosthetic valves. By comprehensively addressing all components of outflow obstruction and mitral dysfunction, this combined procedure may produce better results in certain subsets of HOCM, with the excellent late prognosis of artificial chordal replacement.

Dilated cardiomyopathy is often complicated by severe mitral regurgitation (MR) caused by dilation of the annulus. Heart transplantation remains the ultimate treatment when heart failure fails to respond to medical treatment. Mitral annuloplasty for severe MR in dilated or ischemic cardiomyopathy may delay or replace the need for heart transplantation. The case is reported of a six-year-old child with dilated cardiomyopathy, severe MR and high pulmonary arterial pressure. Following beneficial mitral annuloplasty in 1989, the patient is in excellent functional condition eighteen years later.

Background and aim of the study: The technique of strut chordaesc (SC) cutting, which was proposed for the correction of ischemic mitral regurgitation, has been shown to be an effective short-term procedure. However, the effects of SC cutting on other chordal tensions are unknown. The study aim was to assess anterior leaflet marginal chord tensions after SC cutting. Methods: Tensions of anterior leaflet marginal chordae were measured before and after the cutting of each strut chord independently, or of both SC together, in an intact porcine mitral valve. The cutting positions were chosen between intermediate and marginal chord branching positions. Transmitral pressures were 120 and 160 mmHg. A total of 12 mitral valves was tested. Results: At a transmitral pressure of 120 mmHg, anterolateral SC cutting increased the tension of the marginal chord from the anterolateral papillary muscle (from 0.10 +/- 0.02 to 0.29 +/- 0.11 N; p = 0.02), but not from the posteromedial papillary muscle. At a transmitral pressure of 120 mmHg, posteromedial SC cutting significantly increased the tension of the marginal chord from the posteromedial papillary muscle (from 0.08 +/- 0.03 to 0.34 +/- 0.20 N; p = 0.029), but not from the anterolateral papillary muscle. Cutting both SC at a transmitral pressure of 120 mmHg increased the tension of the marginal chord from both the posteromedial papillary muscle (from 0.09 +/- 0.04 to 0.40 +/- 0.26 N; p = 0.001) and from the anterolateral papillary muscle (from 0.11 +/- 0.03 to 0.48 +/- 0.13 N; p <0.000001). Conclusion: Cutting either of the SC significantly increases the tension of the anterior leaflet marginal chord from the same papillary muscle, but not from the other papillary muscle. Cutting both SCs significantly increases the anterior leaflet marginal chord tensions from both papillary muscles by approximately four-fold.

Background and aim of the study: Ischemic mitral regurgitation is present in a substantial proportion of patients presenting for coronary revascularization. Although patients with even mild to moderate ischemic mitral regurgitation (IMR) have a poorer long-term outcome, mitral valve repair in these cases can be unreliable due to the posterior leaflet tethering that commonly occurs. The aim of this animal-based study was to evaluate a novel technique to effect such a repair. Methods: IMR was produced in six greyhound dogs by tying off the circumflex coronary artery; a mitral valve repair was then performed on cardiopulmonary bypass (CPB). Two hitching sutures from the posteromedial papillary muscle (PPM) to the annulus were individually assessed using epicardial echocardiography when the dogs had been weaned off CPB. Results: Acute dilatation of the heart with PPM displacement and mitral regurgitation were produced in this acute infarct model. Both hitching sutures shortened the distance from the free edge of the posterior leaflet to the PPM tip and reduced its displacement, with a resultant reduction in mitral regurgitation. Conclusion: This simple repair technique may be a useful adjunct to annuloplasty in the treatment of ischemic mitral regurgitation.

Background and aim of the study: The initial application of repair to rheumatic mitral disease was fraught with unacceptable recurrence rates. For this reason, rheumatic valves primarily have been replaced in recent years. Early and late outcomes with replacement, however, have continued to be suboptimal, prompting a re-examination of repair. Methods: All eight patients encountered by the authors with rheumatic mitral valve disease over the past three years were considered for valve repair. One patient had pure stenosis, three patients had pure regurgitation, and four had advanced forms of mixed stenosis and regurgitation. Because posterior leaflet retraction was a prominent and almost uniform feature of rheumatic disease, posterior leaflet glutaraldehyde-fixed autologous pericardial gussets were placed in all cases. In the five patients with stenosis, commissural calcium was debrided, the thickened chords to the anterior leaflet were resected, extended commissurotomies performed, and an anterior leaflet 'hinge' mechanism restored. The anterior leaflet then was reattached to the base of the papillary muscles using Gore-Tex artificial chords, and all eight patients had full ring annuloplasties. Results: Postoperatively, all patients had negligible gradients and no residual leak. The first patient (with mixed stenosis and regurgitation) was restudied with transesophageal echocardiography after three years, and had continued excellent valve function. There have been no intermediate-term recurrences, complications or mortalities. Operative videos and echocardiograms from these patients are available at JScottRankinMD.com. Conclusion: A combination of pericardial posterior leaflet gusset, anterior leaflet chordal resection/GoreTex replacement, extended commissurotomy and full ring annuloplasty allows the repair of rheumatic valves over a full range of pathologies. Early and intermediate-term results appear satisfactory. Continued aggressive application of this type of repair to rheumatic mitral disease seems to be indicated.

Background and aim of the study: Valve-sparing aortic root replacement techniques have been developed to treat sinus of Valsalva aneurysms. Finite-element models have been used to investigate the effects of altering sinus geometry and aortic root modulus on leaflet stress and strain, which may relate to long-term valve competence. However, these studies have assumed the same material properties for the ascending aorta and aortic sinuses. The study aim was to compare the material properties of the ascending aorta and aortic sinuses in porcine roots. Methods: Square specimens, oriented in the longitudinal and circumferential directions, were excised from porcine ascending aorta and aortic sinuses. Specimens were subjected to equibiaxial mechanical stretch testing. Stress-strain data from the aortic sinuses were fitted to a Fung form strain energy function, whereas ascending aortic data were fitted to a Hookean form. Tissue stiffness was compared at 0.35 Green strain. Results: The ascending aorta demonstrated a relatively linear response, unlike the non-linear response of the aortic sinuses. The ascending aorta was stiffer in the circumferential than the longitudinal direction (304.74 +/- 86.47 versus 249.38 +/- 69.81 kPa, p = 0.003), as was the aortic sinus (436.97 +/- 176.30 versus 393.24 +/- 156.10 kPa, p = 0.015). Compared to the sinuses, the ascending aorta was significantly more compliant in both longitudinal (p = 0.001) and circumferential (p = 0.007) directions. Conclusion: Both, the ascending aorta and aortic sinuses demonstrated anisotropy, with the circumferential direction stiffer than the longitudinal. However, the aortic sinuses were significantly stiffer than the ascending aorta. Finite-element modeling of the aortic root should incorporate such critical differences in the material properties.

Background and aim of the study: In aortic stenosis (AS), serum levels of brain natriuretic peptide (BNP) are elevated, but the relation of this elevation to the degree of left ventricular hypertrophy (LVH) remains unclear. The study aim was to assess the relationship between BNP and LVH (expressed as LV mass index, LVMI) and LV wall thickness index (WThI) in a group of patients. Methods: A total of 147 patients with AS (85 men, 62 women; mean age 61 +/- 12 years) each underwent echocardiography and serum BNP analysis. The correlation between serum BNP level and LVH was investigated, with patient gender, age, NYHA class, AS severity and presence of coronary artery disease also being taken into account. Results: Among AS patients, serum BNP levels ranged from 3 to 2010 pg/ml; mean BNP levels were similar in women and men (213 +/- 302 and 253 +/- 375 pg/ml, respectively). The BNP level also correlated directly with the LVMI (r = 0.55; p <0.0001), WThI (r = 0.26; p <0.001), end-diastolic dimension (r = 0.43; p <0.0001), mean aortic gradient (r = 0.25; p = 0.002), age (r = 0.27; p = 0.001); and correlated inversely with the LV ejection fraction (r = -0.52; p <0.0001). Eccentric LVH was associated with a significantly higher serum BNP level (506 +/- 558 pg/ml) than concentric-type hypertrophy (190 +/- 254 pg/ml; p = 0.002). Conclusion: The measurement of serum BNP levels is of potential value when monitoring LVH in aortic stenosis patients.