Bileaflet Mechanical Prosthesis Research Articles

Effective Orifice Area during Exercise in Bileaflet Mechanical Valve Prostheses

The aims of this study were to investigate the evolution of the transprosthetic pressure gradient and effective orifice area (EOA) during dynamic bicycle exercise in bileaflet mechanical heart valves and to explore the relationship with exercise capacity. Patients with bileaflet aortic valve replacement (n=23) and mitral valve replacement (MVR; n=16) prospectively underwent symptom-limited supine bicycle exercise testing with Doppler echocardiography and respiratory gas analysis. Transprosthetic flow rate, peak and mean transprosthetic gradient, EOA, and systolic pulmonary artery pressure were assessed at different stages of exercise. EOA at rest, midexercise, and peak exercise was 1.66±0.23, 1.56±0.30, and 1.61±0.28cm2, respectively (P=.004), in aortic valve replacement patients and 1.40±0.21, 1.46±0.27, and 1.48±0.25cm2, respectively (P=.160), in MVR patients. During exercise, the mean transprosthetic gradient and the square of transprosthetic flow rate were strongly correlated (r=0.65 [P<.001] and r=0.84 [P<.001] for aortic valve replacement and MVR, respectively), conforming to fundamental hydraulic principles for fixed orifices. Indexed EOA at rest was correlated with exercise capacity in MVR patients only (Spearman ρ=0.68, P=.004). In the latter group, systolic pulmonary artery pressures during exercise were strongly correlated with the peak transmitral gradient (ρ=0.72, P<.001). In bileaflet mechanical valve prostheses, there is no clinically relevant increase in EOA during dynamic exercise. Transprosthetic gradients during exercise closely adhere to the fundamental pressure-flow relationship. Indexed EOA at rest is a strong predictor of exercise capacity in MVR patients. This should be taken into account in therapeutic decision making and prosthesis selection in young and dynamic patients.

Anticoagulation for prosthetic heart valves: unresolved questions requiring answers.

The efficacy of anticoagulation for valvular prostheses is the result of a delicate balance between the risk of thromboembolic (TE) events and bleeding. Here, we review data on anticoagulation for valve prostheses with a focus on clinical trials that address key unanswered questions. There are several unanswered questions in the field of prosthetic valve anticoagulation, including: optimal TE prophylaxis in the short term for bioprostheses, optimal TE prophylaxis following transcatheter aortic valve implantation, the safety and efficacy of lower levels of anticoagulation with the bileaflet mechanical prosthesis, the role of aspirin for patients with mechanical prostheses, and the management of anticoagulation for mechanical valves in pregnancy. Other areas of study include the role, if any, of nonwarfarin oral anticoagulants for prosthetic TE prophylaxis as well as self-INR monitoring. Finally, we briefly mention studies of newer anticoagulants, such as novel vitamin K antagonists and antisense oligonucleotides, that are on the horizon. Optimal antithrombotic management is a key issue for patients with valvular prostheses, and the publication of recent trials has provided much-needed guidance. We highlight areas of progress, in addition to the major unanswered questions for which well-designed, prospective clinical trials are forthcoming.

A Congenital Gerbode Defect associated with a Rare Structural Abnormality of the Mitral Valve Diagnosed in an Adult Patient.

We report the case of a rare association of a congenital Gerbode defect with severe mitral regurgitation due to abnormal linear structure of mitral valve, diagnosed in an adult patient. The case highlights the importance of a thorough examination interpreting the echocardiographic findings on a pathophysiological basis. It also underlines the complementary role of different imaging techniques with transesophageal echocardiography, allowing the precise assessment of both structural and functional abnormalities in such a complex case. The patient underwent mitral valve replacement with a bileaflet mechanical prosthesis and repair of the Gerbode defect. The imaging findings were confirmed during the surgical procedure, leading to a good outcome.

An Unusual Case of Tricuspid Regurgitation

We present the case of a 74-year-old woman who was referred to us with dyspnea on mild exertion. The patient had undergone surgical commissurotomy to treat rheumatic mitral stenosis at the age of 28 years, and 29 years later, underwent a second intervention for mitral and tricuspid valve replacement with a double mechanical prosthesis. Ten years before coming to us, she had had surgery at another center for pacemaker implantation due to atrioventricular block; since then, she had not undergone follow-up. In addition to marked cardiomegaly attributable to enlargement of the right chambers, the radiographic study (Figure 1A and 1B) showed the end of the pacemaker lead passing through the tricuspid valve prosthesis and into right ventricle. A transthoracic echocardiogram confirmed the passage of the lead through the prosthesis, which was somewhat thickened and showed evidence of fibrosis, and was associated with severe regurgitation (Figure 2A and 2B, videos 1-3 of the supplementary material). Subsequent transesophageal echocardiography showed a normally functioning mitral valve prosthesis and confirmed the findings of the transthoracic study (Figure 2C, transmitral gradients; Figure 2D, reconstruction of the tricuspid valve prosthesis; videos 4-6 of the supplementary material). The images obtained by fluoroscopy (Figure 3A and 3B, videos 7 and 8 of the supplementary material) demonstrated the interaction between prosthesis and lead, which impeded the closure of the medial hemidisc of the former during systole. After 3 years of follow-up, the patient remains in New York Heart Association class II and refuses to undergo an intervention to remove the lead. This case, the first in the literature, shows that the passage of a permanent pacemaker lead through a bileaflet mechanical prosthesis is unacceptable, as it triggers severe valve regurgitation and increases the risk of degeneration of the lead and of the prosthesis itself over time.

The Application of Bileaflet Mechanical Heart Valves in the Polish Ventricular Assist Device: Physical and Numerical Study and First Clinical Usage.

The Polish ventricular assist device (Polvad) has been used successfully in clinical contexts for many years. The device contains two single-disc valves, one at the inlet and one at the outlet connector of the pneumatic pump. Unfortunately, in recent years, a problem has occurred with the availability of single-disc valves. This article presents the possibility of using bileaflet mechanical heart valve prostheses in the Polvad to avoid a discontinuity in clinical use. The study is based on experimental and numerical simulations and comparison of the distribution of flow, pressure, and stress (wall, shear, and turbulent) inside the Polvad chamber and the inlet/outlet connectors fitted with Sorin Monodisc and Sorin Bicarbon Fitline valves. The type and orientation of the inlet valve affects valve performance and flow distribution inside the chamber. Near-wall flow is observed for single-disc valves. In the case of bileaflet valves, the main jet is directed more centrally, with lower shear stress but higher turbulent stress in comparison with single-disc valves. For clinical usage, a 45° orientation of the bileaflet inlet valve was chosen, as this achieves good washing of the inlet area near the membrane paste surface. The Polvad with bileaflet valves has now been used successfully in our clinic for over a year and will continue to be used until new assist devices for heart support are developed.

Reduced anticoagulation is safe in high-risk patients with the On-X mechanical aortic valve.

The goal of anticoagulation in patients with mechanical aortic valve replacement (AVR) is to maintain an optimal international normalized ratio (INR) that minimizes both the risk of bleeding and thromboembolic events. Here, we review the published data on anticoagulation with bileaflet mechanical prostheses, with a focus on the On-X valve (On-X Life Technologies, Austin, TX), which was designed to function with less anticoagulation or, in some cases, antiplatelet therapy only. Several long-term follow-up studies with the On-X valve demonstrate low rates of bleeding and thromboembolism with standard and low-dose anticoagulation. The Prospective Randomized On-X Anticoagulation Clinical Trial (PROACT) compared the safety of less aggressive anticoagulation (INR 1.5-2.0) with standard anticoagulation (INR 2.0-3.0) after implantation of On-X aortic prostheses for patients at high risk of thromboembolic events. The updated 5-year data confirm that low-dose warfarin is associated with lower major bleeding (1.6 vs. 3.9%/patient-year; P = 0.007) with no difference in thromboembolic events (0.11 vs. 0.52%/patient-year; P = 0.2). Nonrandomized studies and the PROACT data support the safety and efficacy of maintaining the On-X bileaflet mechanical aortic valve prosthesis at a lower target INR than current guideline recommendations for patients at high risk of thromboembolic events. These results offer the promise of a valve prosthesis with excellent durability combined with reduced anticoagulation-related complications.

Mitral prosthetic valve thrombosis and cardiogenic shock in a limited resource setting in sub-Saharan Africa: A tailored treatment approach

We thankDrDoganandColleaguesfor their commentonourprevi-ously described case [1] and for their contribution on the therapy ofprosthetic valve thrombosis (PVT) during pregnancy [2–4].Wetreatedwiththrombolysisa21year-oldUgandanfemalepatientwith known rheumatic heart disease for highly suspected acute PVT,who had undergone mitral valve replacement with a bileaflet mechan-icalprosthesis(St.Judeno.29)aboutthreemonthsbefore[1].Diagnosiswas based on clinical evaluation and transthoracic echocardiography(TTE).The occurrence of acute PVT was likely due to poor internationalnormalized ratio (INR) control and limited patient's compliance toanticoagulation therapy (warfarin).ItmustbeunderlinedthattheyoungpatientwasnotpregnantatthetimeofacutePVT.Pregnancyoccurredsubsequently,asdescribedinourcase report [1]. The fact that the patient was not pregnant made PVTmanagement easier, particularly the choice to initiate thrombolysis.Furthermore, at that time (May 2011) no urgent prosthetic valve re-placementcouldbeperformedinUganda[5].Thus,theonlymedicalop-tion was thrombolysis. Of further relevance, the patient with highlysuspected PVT was in cardiogenic shock, with evidence of multi-organfailure as demonstrated by anuria and high INR value (INR 9) likely relat-ed to acute liver failure [6]. For this reason, vitamin K was administeredand emergent thrombolysis was performed (standard intravenous bolusof tenecteplase) [7]. With regard to echocardiographic diagnosis, notransesophageal probe was available in the hospital where the patientwastreatedatthetimeoftheevent.Accordingtothe2014AHA/ACCVal-vularHeartDiseaseGuidelinebothTTEandtransesophagealechocardiog-raphy (TEE) are recommended for the evaluation of a suspected PVT(classI, levelofevidence Bforbothapproaches) [7]. However,webelievethat in the setting of hemodynamic instability TEE is not always essentialand should beused with caution. For instance, this is the case of hemo-dynamicallyunstablepatientswithatrialfibrillation(AF)andhighven-tricular response rate [8], where the benefit of immediate electricalcardioversion overwhelms the thromboembolic risk in the absence ofpreliminary TEE screening. Invasive mechanical ventilation and man-agement of cardiogenic shock with inotropic agents and/or mechanicalcirculatory support could potentially allow hemodynamic stabilizationof the patient, thus permitting further investigations such as TEE orfluoroscopy. It is worth underlining how Biteker and Ozkan were ableto manage a hemodynamically unstable patient (blood pressure atpresentation 65/35 mm Hg) and perform TEE, which allowed the iden-tificationofalargeprostheticthrombus(1.6×1cm)[9].Intheirreport-ed case a 40 mm Hg mean diastolic mitral transvalvular gradient andclinical history were highly suggestive of PVT [9]. Referring to ourcase, at less than three months after valve replacement pannus forma-tion seemed less likely than acute thrombosis; on the other hand, nosystemicsignssuggestiveofendocarditiswerepresent,makingthisdif-ferential diagnosis unlikely too. Micro-emboli can cause distal cerebralischemiceventsafteracutethrombolysis,anditispossiblethataslowerinfusion of thrombolytic treatment can reduce this risk as comparedwith a standard administration protocol, although no evidence canfully support a strategy over the other. Particularly in patients in AF(like our patient was), TEE demonstration of thrombus in the left atrialappendage would add information about a potential risk of embolicevents; nevertheless, thrombus identification in the appendage in thereportedoccasionwould havenot substantiallymodi fiedourtherapeu-tic strategy.Finally, TEE-guided low-dose, slow infusion of tissue-type plas-minogen activator with repeateddoses have been demonstrated asasafeandsuccessfulstrategybyOzkanetal.[2,3]. We personallyhave no direct experience on thrombolysis in PVT in pregnancy. Itappears reasonable that thefinal decision on the best approach–surgery versus thrombolysis– be related to the experience of the

An unusual cause of left ventricular outflow tract obstruction: obstructive pannus on the left ventricular side of a mechanical mitral prosthesis.

A 37-year-old female, who had undergone mitral valve replacement with a monoleaflet mechanical prosthesis for mitral stenosis in 1997, was admitted to outpatient clinic with exertional dyspnea and chest discomfort over preceding 3 months. Her physical examination revealed mildly muffled prosthetic valve sounds, pansystolic murmur on lower left sternal border, and bilateral fine rales at the bases of the lungs. Her electrocardiography showed atrial fibrillation. Transthoracic echocardiography revealed severe left ventricular outflow tract (LVOT) obstruction with mean gradient of 42 mmHg (Fig. 1a, c; Video 1) and severe tricuspid regurgitation. Two-dimensional transesophageal echocardiography (2D-TEE) showed stenosis of mechanical mitral valve (MMV) with pressure half-time (PHT) of 157 ms (PHT was 98 ms in the previous echocardiography) and mean gradient of 13 mmHg. Aortic valve function and leaflet motion of MMV were normal, but there was a hyperechogenic appearance at the ventricular side of the MMV. With the transducer array at 120 , 2D-TEE revealed that the hyperechogenic mass on the ventricular side of the MMV caused narrowing of the LVOT (Fig. 2a; Video 2). Real-time three-dimensional transesophageal echocardiography (RT-3D-TEE) clearly delineated an eccentric semicircular pannus overgrowth which was located anteriorly on the ventricular side of the MMV (Fig. 2b; Video 3), resulting in LVOT obstruction (Fig. 2c; Video 4). Redo mitral valve replacement with a bileaflet mechanical prosthesis (no. 29, St. Jude Medical) and concomitant repair of the tricuspid valve were performed, and anteriorly eccentric semicircular pannus tissue was removed from the left ventricular side of the mitral prosthesis (Fig. 2d). Postoperative transthoracic echocardiography (TTE) revealed normal functioning mitral prosthetic valve with normal LVOT gradients (Fig. 1b, d; Video 5). Prosthetic heart valve obstruction caused by pannus formation is an uncommon but serious complication. Determination of the precise etiology of valvular obstruction is essential, as this can have an impact on the course of surgical versus thrombolytic therapy [1]. Although 2DTEE is the first method of choice in the diagnostic algorithm, exact visualization of pannus is almost impossible [2]. However, RT-3D-TEE is a very useful imaging technique and permits differentiation of pannus overgrowth from other MMV pathologies [3, 4]. Herein, we present an anteriorly localized eccentric pannus overgrowth on the left ventricular side of MMV, which is an uncommon cause of LVOT obstruction.

Intermittent Entrapment of a Prosthetic Mitral Valve Disc

A 42-year-old man had undergone mitral valve (MV) replacement 12 years earlier with the use of a CarboMedics bileaflet mechanical prosthesis (Sorin Biomedica). On a routine visit, he was asymptomatic, and cardiac auscultation revealed closing and opening MV clicks. A transthoracic echocardiogram with the use of a 2-beat acquisition protocol showed normal excursion of both MV discs (Figure 1; Movie I in the online-only Data Supplement). Spectral Doppler of transmitral flow indicated normal peak gradients; however, abnormalities in the Doppler signal were intermittently noted. Whereas some cardiac cycles showed normal disc motion with near-simultaneous opening clicks, other cycles demonstrated a delay in 1 opening click or a single rather than dual opening clicks (Figure 2). The beats with a single opening click were associated with significant prolongation of the transmitral pressure half-time suggestive of obstruction to flow. The abnormalities on spectral Doppler prompted us to reimage the MV over several cardiac cycles. Intermittent delay in the opening of 1 disc with periodic disc entrapment in a closed position was noted (Figure 3;Movie II in the online-only Data Supplement). Interrogation with color Doppler showed intermittent …

Reduced anticoagulation after mechanical aortic valve replacement: Interim results from the Prospective Randomized On-X Valve Anticoagulation Clinical Trial randomized Food and Drug Administration investigational device exemption trial

Under Food and Drug Administration investigational device exemption, the Prospective Randomized On-X Anticoagulation Clinical Trial (PROACT) has been testing the safety of less aggressive anticoagulation than recommended by the American College of Cardiology/American Heart Association guidelines after implantation of an approved bileaflet mechanical valve. In this first limb of the PROACT, patients with elevated risk factors for thromboembolism were randomized at 33 US centers to receive lower dose warfarin (test international normalized ratio [INR], 1.5-2.0) or continue standard warfarin (control INR, 2.0-3.0), 3 months after mechanical aortic valve replacement. The INR was adjusted by home monitoring; all patients received 81 mg aspirin daily. Adverse events were independently adjudicated. A total of 375 aortic valve replacement patients were randomized into control (n=190) and test (n=185) groups from September 2006 to December 2009. The mean age ± standard deviation was 55.2 ± 12.5 years; 79% were men; and 93% were in sinus rhythm preoperatively. Calcific degeneration was present in 67%; active endocarditis was excluded. Concomitant procedures included coronary artery bypass grafting (27%), aortic aneurysm repair (14%), and other (25%). The follow-up duration averaged 3.82 years (755.7 patient-years [pt-yrs] for control; 675.2 pt-yrs for test). The mean INR was 2.50 ± 0.63 for the control and 1.89 ± 0.49 for the test groups (P<.0001). The test group experienced significantly lower major (1.48% vs 3.26%/pt-yr; P=.047) and minor (1.32% vs 3.41%/pt-yr; P=.021) bleeding rates. The incidence of stroke, transient ischemic attack, total neurologic events, and all-cause mortality were similar between the 2 groups. INR can be safely maintained between 1.5 and 2.0 after aortic valve replacement with this approved bileaflet mechanical prosthesis. With low-dose aspirin, this resulted in a significantly lower risk of bleeding, without a significant increase in thromboembolism.

Vanishing pulmonary oedema, a visual delight!

A forty-two year male patient with bileaflet mechanical mitral valve prosthesis presented with sudden onset breathlessness and haemodynamic collapse. He was in New York Heart Association (NYHA) class IV status with a pulse rate of 120 b.p.m. and blood pressure of 90/60 mmHg. Bilateral extensive crepitations over lung fields could be auscultated. He had stopped oral anticoagulation for past 15 days and had a subtherapeutic international normalized …

Mechanical Prosthesis Is Reasonable for Mitral Valve Replacement in Patients Approximately 65 Years of Age

The long-term results of mitral valve replacement (MVR; n = 631) with a bileaflet mechanical prosthesis or a Carpentier-Edwards Perimount bioprosthesis were evaluated in Japanese patients of different age groups. A total of 507 bileaflet mechanical prostheses and 124 bioprostheses have been implanted since 1982 at our institution. Follow-up was completed for 6,598 patient-years in 98.4% of the cases. Among the patients 70 years of age and older, the rate of freedom from valve-related death and valve-related morbidity at 10 years after surgery were significantly better in the bioprostheses group (93.3% ± 6.4% and 83.7% ± 8.7%, respectively; n = 35) than in the mechanical prostheses group (71.1% ± 8.0% and 60.9% ± 8.9%, respectively; n = 82), and neither structural valve deterioration (SVD) nor resulting re-MVR were observed for bioprostheses. In contrast, among the patients 64 years and younger, no significant differences were observed in long-term survival between the mechanical prostheses group (n = 347) and the bioprostheses group (n = 76), while significantly lower rates of freedom from SVD and re-MVR were observed in the bioprostheses group compared with those obtained in the mechanical prostheses group. As for the controversial intermediate-age group of 65 to 69 years, the general tendencies were similar to those observed in the group 64 years and younger. Based on our comparative evaluation, bioprostheses should be chosen for MVR in patients 70 years of age and older, whereas mechanical prostheses were better in the patients 64 years of age and younger. The use of bioprostheses in Japanese patients 65 to 69 years of age is not preferable for preventing SVD and subsequent re-MVR.

EComment. A novel lower age threshold for use of biological valves

The publication by Niclauss et al. [1] highlights a subject with conflicting results in the literature: the determination of a lower age limit for bioprosthetic valves in the aortic position. They concluded that biological aortic valve replacement could be an alternative treatment option for patients between 56 and 60 years old at the time of surgery. Nevertheless, biological aortic valves in patients younger than 60 years old is still a matter of ongoing debates, and the debate has gained renewed impetus with the advent of transcatheter aortic valve implantation and the feasibility of valve-in-valve procedures [2]. Moreover, valve-related complications in this patient population have not been clearly investigated. It is noteworthy that in two recently published studies, mechanical valves among younger patients were shown to have more superior clinical outcomes compared to bioprostheses. Badhwar et al. [3], who conducted a prospective study on 172 propensity-matched patients, demonstrated a significantly lower mortality rate in patients with mechanical prostheses after 4 years of follow-up. Of note, patients with bileaflet mechanical prostheses enrolled in the above-mentioned study were monitored at low international normalized ratio thresholds using point-of-care home monitoring. The merits of mechanical aortic valve have been reiterated by the study of Weber et al. [4]. They selected a cohort of 103 patients younger than 60 years old with the Perimount Carpentier-Edwards pericardial tissue valve and compared them with a propensity matched group of 103 patients with mechanical bileaflet aortic valve over a period of 10 years. Surprisingly, valve-related event rates were similar in both groups; however, survival was significantly reduced in patients with bioprostheses (90% vs 98%). One possible explanation speculated by the authors was the protective role of oral anticoagulation in patients with mechanical valves. The current guidelines from major international cardiovascular societies propose that both valve types are acceptable in patients aged between 60 and 65 years at the time of surgery. However, there is still insufficient evidence to recommend biological valves for patients younger than 60 years, other than in patients who have major medical contraindications to anticoagulant therapy. Conflict of interest: none declared.

Influence of Type of Aortic Valve Prosthesis on Coronary Blood Flow Velocity

Severe aortic valve stenosis is associated with high resting and reduced hyperemic coronary blood flow. Coronary blood flow increases after aortic valve replacement (AVR); however, the increase depends on the type of prosthesis used. The present study investigates the influence of type of aortic valve prosthesis on coronary blood flow velocity. The blood flow velocity in the left anterior descending coronary artery (LAD) and the right coronary artery (RCA) was measured intraoperatively before and after AVR with a stentless bioprosthesis (Sorin Freedom Solo; n = 11) or a bileaflet mechanical prosthesis (St. Jude Medical Regent; n = 11). Measurements were made with an X-Plore epicardial Doppler probe (Medistim, Oslo, Norway) following induction of hyperemia with an adenosine infusion. Preoperative and postoperative echocardiography evaluations were used to assess valvular and ventricular function. Velocity time integrals (VTI) were measured from the Doppler signals and used to calculate the proportion of systolic VTI (SF), diastolic VTI (DF), and normalized systolic coronary blood flow velocities (NSF) and normalized diastolic coronary blood flow velocities (NDF). The systolic proportion of the LAD VTI increased after AVR with the St. Jude Medical Regent prosthesis, which produced higher LAD SF and NSF values than the Sorin Freedom Solo prosthesis (SF, 0.41 ± 0.09 versus 0.29 ± 0.13 [P = .04]; NSF, 0.88 ± 0.24 versus 0.55 ± 0.17 [P = .01]). No significant changes in the LAD velocity profile were noted after valve replacement with the Sorin Freedom Solo, despite a significant reduction in transvalvular gradient and an increase in the effective orifice area. AVR had no effect on the RCA flow velocity profile. The coronary flow velocity profile in the LAD was significantly influenced by the type of aortic valve prosthesis used. The differences in the LAD velocity profile probably reflect differences in valve design and the systolic transvalvular flow pattern.

A Successful Dissolution of an Obstructive Prosthetic Mitral Valve Thrombus: Sequential Two and Three Dimensional Transesophageal Echocardiography Examination

A 51-year-old man presented to other hospital with onset dyspnea on exertion. Earlier he had aortic and mitral valve replacement with a bileaflet mechanical prosthesis. Later he developed obstructive prosthetic mitral valve thrombosis (OPMVT). He underwent urgent surgery, with removal of the prosthetic mitral valve and thrombus. Latest, he had a transient ischemic attack. This time he was given intravenous diuretics and heparin, and was transferred to our hospital. Clinical history and physical examination suggested probable prosthetic valve thrombosis. Because of poor transthoracic echocardiography, we resorted to two-dimensional and real-time three-dimensional transesophageal echocardiography (2D TEE, RT3DTEE) 1) and these showed that one leaflet (L2) was opening fully, while the other leaflet (L1) was completely blocked by a small thrombus (Fig. 1A and B, Supplementary movie 1 and Supplementary movie 2). The mean mitral gradient was 23 mmHg, and pressure half-time was 296 msec. We opted for medical treatment2) using intravenous heparin for ten days followed by oral anticoagulation adjusted to a target international normalized ratio (INR) of 3.0-3.5. Aspirin 100 mg daily was initiated with the heparin. Daily INR was started for close monitoring of anticoagulation. The patient's presenting symptoms resolved. Weekly follow-up TEE was carried out. At the end of fourth week this showed normal function of mitral prosthesis, as well as resolution of the small thrombus mentioned (Fig. 1C and D, Supplementary movie 3 and Supplementary movie 4). Medical treatment under TEE monitoring, with spatial assessment of the OPMVT gathered by RT3DTEE, may be considered as a first-line treatment of OPMVT. Fig. 1 Two dimensional transesophageal echocardiogram (2D TEE) showing one leaflet (L1) blocked, while the second leaflet (L2) is opening with accelerated color flow velocity (A). Real time three dimensional transesophageal echocardiogram (RT3DTEE) view from ...

Apicoaortic Conduit: A Simple Solution to a Difficult Problem

Apicoaortic conduit is a nonanatomic method of providing forward flow from the left ventricle. It is used as an alternative to aortic valve replacement in patients with comorbid factors that preclude a safe approach via median sternotomy. Our patient had undergone aortic and mitral valve replacements with bileaflet mechanical prostheses. After almost a decade, he started to experience recurrent episodes of congestive heart failure requiring hospitalization. Preoperative transesophageal echocardiography and computed tomography of the chest were done for evaluation. The 21-mm Carbomedics bileaflet aortic prosthesis (Sorin Group USA Inc, Arvada, CO) provided an effective orifice area index of 0.58 cm2/m2, leading to severe patient-prosthesis mismatch.1 A compounding factor was significant subvalvar stenosis (Panel A, arrows) due to the hypertrophied small left ventricle and the abnormal axis of the mechanical mitral valve (Panel A, asterisk). The ascending aorta measured 2.5 cm at the sinotubular junction, which is also smaller than normal (2.1-3.4 cm).2 The small hypertrophied left ventricle (LV) (Panel A, arrows) had a high end-diastolic pressure as demonstrated by the dilated left atrium (Panel A, LA). The multiple levels of left ventricular outflow tract obstruction made a corrective procedure via median sternotomy very high risk. Because of the abnormal placement of the mitral valve (Panel A, asterisk), we did not feel that we would be able to relieve the subvalvar stenosis even with myectomy. An apicoaortic conduit (Panel C, arrow) was constructed between the left ventricular apex (LVA) and the descending thoracic aorta (DTA) via a left thoracotomy. Normothermic cardiopulmonary bypass was achieved by cannulation of the left common femoral artery and vein. The left ventricle was small and hypertrophied with a very small cavity. Two separate pieces of a 16-mm Dacron tube graft (Medtronic, Inc, Minneapolis, MN) were anastomosed to the left ventricular apex (LVA) and the descending thoracic aorta (DTA) (Panel B, white arrows). A 20-mm Dacron graft was interposed between these 2 grafts (Panel B, gray arrow), and a 17-mm bileaflet mechanical valve (St. Jude Medical, St. Paul, MN) was interposed between these conduits. Hence, the combined effective orifice area index was 1.11 cm2/m2. The patient experienced marked symptomatic improvement at dismissal and was counseled regarding strict adherence to therapeutic anticoagulation, as he had 3 mechanical valves in situ. We demonstrate that this procedure is useful for the management of patients with complex left ventricular outflow tract obstruction. It avoids the high risks involved in repeated median sternotomy approach.

078 A randomised study of the effects of bi-leaflet prosthesis orientation on aortic haemodynamics and coronary flow velocity profiles

ObjectivesThe orientation of curved bi-leaflet mechanical prosthesis has been shown to significantly affect the development of aortic sinus flow in the in vitro study. However, its clinical implication for trans-aortic...

Noninferiority of Closely Monitored Mechanical Valves to Bioprostheses Overshadowed by Early Mortality Benefit in Younger Patients

Confidence in bioprosthetic durability without anticoagulation has led to a contemporary trend of offering tissue valves to younger patients. Close monitoring of mechanical valve patients at lower international normalized ratio (INR) thresholds may reduce anticoagulation morbidity. We prospectively compared results of bioprostheses (BP) and a bileaflet mechanical prosthesis (MP) monitored at low INR thresholds. Patients received an isolated Carpentier-Edwards bovine or Medtronic porcine BP or the On-X MP. INR targets were 2.0 for MP recipients undergoing aortic valve replacement and 2.5 for mitral valve replacement, using point-of-care home monitoring. Operations consecutively performed between September 2003 and August 2007 were propensity matched using logistic regression by preoperative covariates of age, sex, valve position, New York Heart Association class, ejection fraction, atrial fibrillation, and creatinine. Of 469 operations consecutively performed, 172 patients were matched for analysis. Mean age was 56.2±9.6 years (range, 24 to 72 years). Median follow-up was 4.0 years (total follow-up, 667.0 patient-years). No late bleeding events occurred. The thromboembolic complication rates per patient-year were 0.77% for MP and 0.78% for BP (p=0.67). There were 9 BP deaths vs 4 MP (2.35% vs 1.41%/patient-year; BP hazard ratio, 0.60; 95% confidence interval, 0.13 to 2.15). Postoperative linearized mortality benefit of MP was observed as early as 5 years, reaching significance at 7.5 years (p=0.04). Patients aged 65 years or younger with MP and closely monitored anticoagulation display noninferiority to BP from bleeding and thromboembolic complications. MP valves begin to confer mortality benefit over BP as early as 7.5 years postoperatively. Because this predates the timeline of typical structural valve degeneration, equipoise is suggested when choosing a BP in a young patient with future expectations of valve-in-valve intervention.

Incremental Value of Three-Dimensional over Two-Dimensional Transesophageal Echocardiography in the Assessment of Acute Dysfunction of Mechanical Mitral Valve Prosthesis

We describe acute dysfunction of a bileaflet mechanical mitral valve prosthesis for the first time in a 57-year-old male. Unlike two-dimensional transesophageal echocardiography, three-dimensional imaging convincingly showed a large rounded echo density consistent with a papillary muscle in contact with one of the leaflets showing only partial opening during systole.

Acute Occlusion of a Bileaflet Mechanical Mitral Valve Prosthesis Resulting from External Cardiac Compression

A 45-year-old woman with a history of rheumatic mitral disease underwent valve replacement. After surgery, the patient became hemodynamically unstable. A transesophageal echocardiogram showed an underfilled left ventricle with a clot impinging on the lateral aspect of the left ventricle and a malfunctioning mitral valve prosthesis. After evacuation of the clot in the operating room, the mitral valve prosthesis began functioning normally. The prosthesis malfunction resulted from external cardiac compression. This dynamic device malfunction was replicated when the surgeon compressed the lateral aspect of the heart. To our knowledge, this dynamic form of leaflet dysfunction from external compression has not been described. This case highlights the importance of closely evaluating prosthetic valve function in the setting of hemodynamic deterioration.