Leaflet Closure Research Articles

Implantation Technique and Early Echocardiographic Performance of Newly Designed Stentless Mitral Bioprosthesis

This article describes the implantation techniques of two new stentless mitral bioprosthesis and their early echocardiographic performance in 12 acute sheep model. The first stentless mitral bioprosthesis (stentless bileaflet valve [SBV]) was designed as a bileaflet valve with sewing ring to suture down to the native mitral annulus. The other one (SBV with chordae) has two chordae-like structures to be attached to the head of the native papillary muscles. Valvar performance and cardiac function were evaluated by epicardial echocardiography at postimplant (Rest) and during dobutamine (DOB) stimulation. Postimplant echocardiography revealed normal leaflet opening with a large orifice area and unrestricted leaflets motion. In both valves, leaflet closure showed no systolic anterior motion, prolapse, or tethering. Mitral regurgitation grade 2 or higher was not detected in any of the experiments. Transvalvar pressure gradients at Rest and DOB were 2.3 ± 1.6 mm Hg and 2.5 ± 2.2 mm Hg in SBV and 1.8 ± 1.1 mm Hg and 2.3 ± 1.2 mm Hg in SBV with chordae, respectively. Both stentless bioprosthesis showed reliable valve performance and preserved cardiac function in the acute phase. Further chronic study is needed to evaluate the reliability of implantation procedures, valvar performance, and biocompatibility.

Polymer Injection Therapy to Reverse Remodel the Papillary Muscles

Background— Ischemic mitral regurgitation (MR) results from displacement of the papillary muscles caused by ischemic ventricular distortion. Progressive left ventricular (LV) remodeling has challenged therapy. Our hypothesis is that repositioning of the papillary muscles can be achieved by injection of polyvinyl-alcohol (PVA) hydrogel polymer into the myocardium in chronic MR despite advanced LV remodeling. Methods and Results— Ten sheep underwent ligation of the circumflex branches to produce chronic ischemic MR over 8 weeks. PVA was injected into the myocardium underlying the infarcted papillary muscle. Two-dimensional and 3D echocardiograms and hemodynamic data were obtained before infarct (baseline), before PVA (chronic MR), and after PVA. PVA injection significantly decreased MR from moderate to severe to trace (MR vena contracta, 5.8±1.2 to1.8±1.3 mm; chronic MR to post-PVA stage; P =0.0003). This was associated with a decrease in infarcted papillary muscle–to–mitral annulus tethering distance (30.3±5.7 to 25.9±4.6 mm, P =0.02), tenting volume (1.8±0.7 to 1.4±0.5 mL, P =0.01), and leaflet closure area (8.8±1.3 cm 2 to 7.6±1.3 cm 2 , P =0.004) from chronic MR to post-PVA stages. PVA was not associated with significant decreases in LV ejection fraction (41±3% versus 40±3%, P =NS), end-systolic elastance, τ (82±36 ms to 72±26, P =NS), or LV stiffness coefficient (0.05±0.04 to 0.03±0.01). Conclusions— PVA hydrogel injections improve coaptation and reduce remodeling in chronic MR without impairing LV systolic and diastolic function. This new approach offers a potential alternative for relieving tethering and ischemic MR by correcting papillary muscle position.

Right ventricular pacing increases tricuspid regurgitation grade regardless of the mechanical interference to the valve by the electrode

The effect of right ventricular (RV) pacing on tricuspid regurgitation (TR) is debatable and is presumed to be related to an interference with valve closure by the electrode. The aim of the study was to determine the impact of pacing per se on TR grade. The study group included 23 clinically stable patients (13 males; mean age 78 +/- 12 years) with a permanent pacemaker at the RV apex (83% DDD mode) and normal left ventricular function. They were all non-dependent on pacing and were otherwise in sinus rhythm. None had a primary dysfunction of the tricuspid valve. TR grade and RV size were assessed in two consecutive echo studies with and without active RV pacing. Results showed that active RV pacing was associated with an increase in TR severity (TR vena contracta: 0.4 +/- 0.2 vs. 0.2 +/- 0.2 cm, P < 0.001; TR jet area: 4.1 +/- 2.3 vs. 2.3 +/- 1.8 cm(2), P < 0.001). This was also reflected in a significant decrease in the number of patients with mild TR (P = 0.003) and increase in the number with moderate regurgitation (P = 0.02). There was no change in RV areas with pacing. Active RV pacing is associated with a significant increase in TR grade. This effect is not induced by acute changes in the RV area and is unrelated to an interference with leaflet closure by the electrode.

Intermittent regurgitation caused by incomplete leaflet closure of the Medtronic ADVANTAGE bileaflet heart valve: Analysis of the underlying mechanism

Clinical echocardiographic assessments of the Medtronic ADVANTAGE (Medtronic Inc, Minneapolis, Minn) prosthesis in the aortic position revealed a phenomenon identified as "intermittent regurgitation." An in vitro investigation was initiated to identify the underlying mechanism. In a pulse duplicator environment, 6 ADVANTAGE size 23 aortic valves were analyzed. Leaflet motion and flow through the valves were documented using echocardiography with color Doppler flow, digital high speed imaging, and flow meter assessment. Intermittent regurgitation could be reproduced in all 6 of the tested valves within limited ranges of flow, pressure, and valve orientation. By virtue of high-speed imaging, the mechanism underlying intermittent regurgitation was identified. During intermittent regurgitation, the leading edge of the second-to-close leaflet makes contact with the chamfer on the leading edge of the first-to-close leaflet. The fluid closing forces working on the first-to-close leaflet prevent it from shifting back so that the leading edge of the second-to-close leaflet remains positioned against the chamfer of the first-to-close leaflet. In this position, the major radius of the second-to-close leaflet does not reach the housing's major radius. Therefore, a crescent-shaped gap remains between the leaflet tip of the second-to-close leaflet and the housing major radius during all or part of diastole. The regurgitant fraction can increase from a normal range of 6% to 25% during an intermittent regurgitation beat. In vitro intermittent regurgitation can be induced in the size 23 aortic ADVANTAGE valve under a limited range of conditions. To avoid possible misinterpretations, the phenomenon must be known in detail by all physicians dealing with patients with an ADVANTAGE valve.

New automated wavelet analytical system with a cellular phone for recording intercellular phone remote transmitted bileaflet valve sound

The wavelet analytical system developed in our institute can detect a malfunctioning bileaflet valve by analyzing the split interval (SI) of bileaflet valve sound (BLVS) caused by asynchronous closure of both leaflets. However, this system is limited in its clinical application because of the complications of both valve sound recording and analytical protocols. This study established a new system that improved upon these limitations, and evaluated its clinical efficiency and the possibility of intercellular phone remote transmission of BLVS (ICTB). Fifty-one valves in 36 patients with St. Jude Medical bileaflet valve replacement were examined by fluoroscopy, 90 BLVS files (42 mitral and 48 aortic valve files) were recorded, and 1720 individual BLVS recordings in these files were analyzed with the new system. The new system consists of a cellular phone for BLVS recording and an automated algorithm for analysis with the Morlet continuous wavelet transform. ICTB was also investigated clinically. The new system showed great improvement over the original system by simplifying BLVS recording and reducing analysis time by approximately 65%. This system detected two malfunctioning valves with coefficients of variation (CV) for SI below 0.112, a previously proposed criterion for malfunction. ICTB also proved to be a useful BLVS recording method for determining SI. The new system described in this study could eliminate the factors limiting clinical application of the old system, and ICTB was found to be a clinically applicable BLVS recording method.

Comparison of Multidetector-Row Computed Tomography to Echocardiography and Fluoroscopy for Evaluation of Patients With Mechanical Prosthetic Valve Obstruction

For evaluation of prosthetic heart valve obstruction echocardiography and fluoroscopy provide primarily functional information but may not unequivocally establish the cause of dysfunction. Our objective was to evaluate whether multidetector-row computed tomographic (MDCT) imaging could detect the morphologic substrate for such functional abnormalities. Thirteen patients with 15 prosthetic valves, in whom prosthetic valve obstruction was suspected from echocardiography or fluoroscopy but no sufficient cause could be found, underwent electrocardiographically gated multidetector-row computed tomography. MDCT data were retrospectively reconstructed at every 10% of the electrocardiographic interval and analyzed using multiplanar reformatting in anatomically adapted planes. MDCT images were evaluated for morphologic prosthetic and periprosthetic abnormalities. Results could be compared to intraoperative findings or autopsy in 7 patients. Multidetector-row computed tomography disclosed a morphologic substrate for obstruction in 8 of 13 patients. MDCT findings compatible with obstruction were confirmed at surgery or autopsy in 6 patients. In a seventh patient, incomplete leaflet closure found with multidetector-row computed tomography was confirmed at surgery. The most commonly identified causes for obstruction were subprosthetic tissue (6 patients) and abnormal anatomic orientation (3 patients). Despite an indication for surgery, 2 patients were not operated on due to recurrent bacteremias and prohibitive co-morbidity. Multidetector-row computed tomography detected leaflet motion restriction in 7 patients compared to 4 by fluoroscopy. Confirmation of leaflet restriction was available in 5 patients. Multidetector-row computed tomography missed a periprosthetic leak. In conclusion, this initial experience demonstrates that multidetector-row computed tomography can identify causes of prosthetic valve obstruction that constitute indications for surgery but are missed at echocardiography or fluoroscopy.

Clinical outcome of mitral valve repair in primary infective endocarditis with mitral insufficiency

To study the clinical results of mitral valve repair in patients of primary infective endocarditis with mitral insufficiency. From January 2004 to July 2007, 40 patients who had undergone valve repair procedure for infective endocarditis with mitral insufficiency were analyzed retrospectively. There were 26 male and 14 female patients, with an average age of (34.0 +/- 3.5) years old, including 6 patients of underlying heart disease, 34 patients of no previously underlying heart disease. There were 12 patients in NYHA functional class II, 19 patients in class III, 9 patients in class IV preoperatively. Preoperative echocardiography showed moderate to severe MR in all patients. The surgery was performed under extracorporeal circulation and moderate hypothermia. The distribution of anatomical lesion according to surgical findings were vegetation in 32 patients, leaflet prolapsed in 34 patients, leaflet perforation in 16 patients, chordal rupture in 32 patients, and annular abscess in 2 patients. The vegetations and infected tissues were debrided. The surgery consisted of complex methods to repair mitral valve, including direction leaflet closure in 5 patients, pericardial patch closure of leaflet perforation in 18 patients, chords reimplantation in 4 patients and chords transference in 6 patients, quadrangular resection in 12 patients, double orifice method in 17, closure of the commissure in 8, rings annuloplasty in 28 cases, and so on. There were 28 selective surgeries and 12 emergent ones. Patients were evaluated for early and long-term clinic and echocardiographic outcome before and after operation. There were no early postoperative death. Mitral valve repair was feasible in 39 patients, one patient was transformed to mitral valve replacement during the operation. Postoperative echocardiography demonstrated no (n = 24) or mild (n = 15) mitral regurgitation at the discharge examination and observed significant reductions in left ventricular end diastolic [from (62 +/- 7) mm to (51 +/- 6) mm, P < 0.05] and end systolic dimensions [from (45 +/- 3) mm to (40 +/- 4) mm, P < 0.05] and left atrial dimensions [from (49 +/- 4) mm to (42 +/- 6) mm, P < 0.05]. Mean follow-up (25.6 +/- 3.2) months, freedom from recurrent moderate to severe MR, freedom from repeat operation or infective endocarditis, revealed patients were 36 cases in NYHY class I, 3 cases in class II. Mitral valve repair for mitral valve endocarditis is feasible with a satisfied clinical outcome, maintains valve competency with significant reductions in left atrial and left ventricular dimensions after surgery.

Methods of estimation of mitral valve regurgitation for the cardiac surgeon.

Mitral valve regurgitation is a relatively common and important heart valve lesion in clinical practice and adequate assessment is fundamental to decision on management, repair or replacement. Disease localised to the posterior mitral valve leaflet or focal involvement of the anterior mitral valve leaflet is most amenable to mitral valve repair, whereas patients with extensive involvement of the anterior leaflet or incomplete closure of the valve are more suitable for valve replacement. Echocardiography is the recognized investigation of choice for heart valve disease evaluation and assessment. However, the technique is depended on operator experience and on patient's hemodynamic profile, and may not always give optimal diagnostic views of mitral valve dysfunction. Cardiac catheterization is related to common complications of an interventional procedure and needs a hemodynamic laboratory. Cardiac magnetic resonance (MRI) seems to be a useful tool which gives details about mitral valve anatomy, precise point of valve damage, as well as the quantity of regurgitation. Finally, despite of its higher cost, cardiac MRI using cine images with optimized spatial and temporal resolution can also resolve mitral valve leaflet structural motion, and can reliably estimate the grade of regurgitation.

Giant cardiac myxoma: Real-time characterization by 64-slice computed tomography

Video clip is available online. Video clip is available online. A 70-year-old woman was admitted at our institution because of recent onset of palpitations, dyspnea, and fatigue. On physical examination, she appeared well and she did not present particular signs except for a pulse rate of 114 beats per minute; her blood pressure was 155/85 mm Hg, axillary temperature was 36.7°C, respirations were 16 breaths per minute, and arterial blood gas measurements were normal. The chemistry and hematologic laboratory values were within the normal reference ranges. Electrocardiography revealed sinus tachycardia at a rate of 115 beats per minute and diphasic P waves in leads II, aVF, and V3 through V5. A chest radiography showed no abnormalities of the heart and mediastinum, and the lungs were clear. However, in the lateral view, an egg-shaped image corresponding to the atria was present and appeared highly suspicious for an intracardiac mass. A transthoracic echocardiographic examination disclosed a dilated left atrium (60 × 40 mm) filled almost entirely by a mobile, pedunculated mass of echoes, 2.7 by 7 cm, that partially prolapsed into the left ventricle during diastole with an incomplete closure of the mitral valve leaflets and an associated jet of mild regurgitation (Figure 1). The mass was highly mobile and appeared to be attached to the interatrial septum by a large stalk (2 cm). Transesophageal echocardiogram was impracticable because of the presence of Zenker's diverticulum. A 64-slice contrast-enhanced computed tomography (LightSpeed VCT, GE Healthcare, Milwaukee, Wis) was performed to confirm the diagnosis. Multiplanar reconstructions exactly defined the tumor attachment in the angle between the upper portion of interatrial septum and the left atrial roof (Figure 1). Functional and dynamic features were obtained by 3-dimensionally rendered real-time reconstructions (Aquarius, Tera Recon, San Mateo, Calif) that demonstrated this huge mass prolapsing through the mitral orifice and greatly reducing the diastolic filling of the left ventricle (Video 1). The patient had an urgent operation. Because of the large dimensions and the site of implant, we preferred a biatrial approach; thus the resection was accomplished in a “septal superior approach fashion.” Actually, by direct visualization, the mass presented a large stalk localized in the upper interatrial septum and widely extending to the roof of the left atrium. The tumor was extracted en bloc, and gross inspection showed a huge trilobulated mass measuring about 4 × 7 × 3 cm with a stalk of 2 × 2 cm (Figure 2). Fresh section revealed a reddish mass with diffuse hemorrhagic infiltration strongly suggestive of cardiac myxoma. Once the mass had been removed, the mitral apparatus was carefully inspected for possible valve incompetence that was preoperatively undetectable. However, the saline solution injection revealed only a trivial central regurgitation not susceptible of surgical correction. The procedure was completed as usual without complications, and the postoperative course was uneventful except for the occurrence of a junctional rhythm, which spontaneously resolved in the third postoperative day. Histology confirmed the diagnosis of myxoma. Usually pedunculated, cardiac myxomas develop in the atria in about 90% of the cases (75% left atrium and 15% to 20% right atrium). Left atrial myxomas originate from the interatrial septum in 85% of the cases (mostly from the fossa ovalis), with the others usually arising from the posterior or anterior atrial wall.1Reyen K. Cardiac myxomas.N Engl J Med. 1995; 333: 1610-1617Crossref PubMed Scopus (996) Google Scholar Giant cardiac myxomas have also been reported in the literature, and when sited in the left atrium, they can give rise to critical drawbacks for diagnosis of coexistent or subsequent mitral valve disease.2Davoli G. Muzzi L. Lucchese G. Uricchio N. Chiavarelli M. Large left atrial myxoma with severe mitral valve regurgitation. The inverted T-shaped biatrial incision revisited.Tex Heart Inst J. 2006; 33: 51-53PubMed Google Scholar Multislice computed tomography is emerging as a useful adjunctive tool in cardiovascular imaging, capable of supplying an extremely accurate, operator-independent definition of anatomic and functional details.3Feuchtner G. Mueller S. Bonatti J. Friedrich G. zur Nedden D. Smekal A. Prolapsing atrial myxoma. Dynamic visualization with multislice computed tomography.Circulation. 2004; 109: e165-e166Crossref PubMed Google Scholar Its great diagnostic power can sometimes cause this technique to be used inappropriately. In our experience, precisely identifying the unusual tumor attachment resulted in a fundamental diagnostic implement for the choice of surgical approach, which is crucial to achieve a radical excision, to avoid the risk of tumor fragmentation (especially for huge myxomas), and to manage a possibly associated valve disease.2Davoli G. Muzzi L. Lucchese G. Uricchio N. Chiavarelli M. Large left atrial myxoma with severe mitral valve regurgitation. The inverted T-shaped biatrial incision revisited.Tex Heart Inst J. 2006; 33: 51-53PubMed Google Scholar Download .mpg (1.29 MB) Help with mpg files Video 1Three-dimensionally rendered real-time reconstruction showing the dynamic mitral inflow obstruction by the tumor.

Three-dimensional Transesophageal Echocardiography for Mitral Valve Repair Surgery - A case report -

Although several reports have showed the application of 3-dimensional (3D) echocardiography, it is hard to find a report regarding the intraoperative use of real time 3D transesophageal echocardiography (TEE) in mitral valve repair surgery. In the present case, real time 3D TEE the one from the one TEE probe position as well as their rotated and cropped images showed detailed spatial images enough for immediate assessment of the mitral valve deformity and the characteristics of mitral regurgitation flow. Under cardiopulmonary bypass (CPB) employing moderate hypothermia, the prolapsed mital leaflet was excised, the ruptured cord was repaired and an annuloplasty ring was inserted to reinforce the mitral valve and to close up the defect. The 2D and 3D TEE images after CPB showed effective repair providing complete closure of the mitral leaflets and absence of residual regurgitation flow. Considering that the conventional 2D TEE requires examiner's ability to gather the various 2D TEE images and experience essential for intergrating the 2D images for full understanding of spatial structure of valvular deformity and dysfunction, 3D TEE's ability for making a comprehensive spatial image from a limited number of 2D images seems to have an additional clinical efficacy in intraoperative TEE monitoring for cardiac value surgery. (Korean J Anesthesiol 2008; 54: 685~8)

In Vitro Mitral Chordal Cutting by High Intensity Focused Ultrasound

Mitral regurgitation, when it arises from functional restriction of mitral leaflet closure, can be relieved by surgical cutting of the mitral tendineae chordae. We hypothesized that high intensity focused ultrasound (HIFU) might be useful as a noninvasive extracorporeal technique for cutting mitral chordae. As a pilot study to test this hypothesis, we examined the in vitro feasibility of using HIFU to cut calf mitral chordae with diameters from 0.2 to 1.6 mm. Sixty-seven percent of chordae were completely cut with HIFU, operated at 4.67 MHz and 45 W acoustic power, with up to 120 pulses of 0.3-s duration at 2-s intervals. Forty-five percent were completely cut when the pulse duration was reduced to 0.2 s. The average diameter of those chordae, which were completely cut, was significantly smaller than that of incompletely cut chordae (0.59 ± 0.30 versus 1.14 ± 0.30 mm with a pulse duration of 0.2 s, p < 0.0001; 0.68 ± 0.29 versus 1.32 ± 0.20 mm with a pulse duration of 0.3 s, p < 0.0001). For each pulse duration, the number of pulses required for complete cutting exhibited a strong positive correlation with the chordae diameter. In conclusion, in vitro feasibility of mitral chordal cutting by HIFU depended on the diameter of chordae but was controllable by HIFU settings. (E-mail: abeyukio@aol.com)

Intermittent incomplete closure of Medtronic Advantage aortic valve leaflets causes unnecessary reoperation

A40-year-old man underwent isolated aortic valve replacement with a 23-mm Medtronic Advantage valve prosthesis (Medtronic, Minneapolis, Minn) for severe stenosis of a bicuspid aortic valve. The valve was implanted with pledgets by the non-everting suture technique and placed with the central orifice pointing in between the coronary ostia. The postoperative course was uneventful, and the patient was discharged on the sixth postoperative day. Control transthoracic echocardiograms were performed before discharge and 6 and 12 months after discharge, all of which showed a normal functioning prosthetic valve with a mean gradient of 12 mm Hg. The patient was in New York Heart Association functional class I and had resumed all his activities within the follow-up.

Three-Dimensional Quantitation of Mitral Valve Coaptation by a Novel Software System with Transthoracic Real-Time Three-Dimensional Echocardiography

We investigated the degree of mitral valve coaptation with a custom quantitation software system using transthoracic three-dimensional (3D) echocardiography. With real-time 3D echocardiography, we obtained transthoracic volumetric images in 20 healthy subjects and 20 patients with dilated cardiomyopathy. With our novel software system, the surface area of mitral valve tenting in the onset of mitral leaflet closure [O] and the timing of maximum closure of mitral leaflet [M] were reconstructed for quantitative measurement. The coaptation index was calculated by the following formula: [(3D tenting surface area in O-3D tenting surface area in M)/3D tenting surface area in O]. The coaptation index in patients with dilated cardiomyopathy was significantly smaller than that in healthy subjects (11% +/- 4.1% vs. 18% +/- 8.0%, P = .004). The custom quantitation software system with 3D echocardiography allowed us to assess the degree of mitral valve coaptation.

Fluid–structure interaction models of the mitral valve: function in normal and pathological states

Successful mitral valve repair is dependent upon a full understanding of normal and abnormal mitral valve anatomy and function. Computational analysis is one such method that can be applied to simulate mitral valve function in order to analyse the roles of individual components and evaluate proposed surgical repair. We developed the first three-dimensional finite element computer model of the mitral valve including leaflets and chordae tendineae; however, one critical aspect that has been missing until the last few years was the evaluation of fluid flow, as coupled to the function of the mitral valve structure. We present here our latest results for normal function and specific pathological changes using a fluid-structure interaction model. Normal valve function was first assessed, followed by pathological material changes in collagen fibre volume fraction, fibre stiffness, fibre splay and isotropic stiffness. Leaflet and chordal stress and strain and papillary muscle force were determined. In addition, transmitral flow, time to leaflet closure and heart valve sound were assessed. Model predictions in the normal state agreed well with a wide range of available in vivo and in vitro data. Further, pathological material changes that preserved the anisotropy of the valve leaflets were found to preserve valve function. By contrast, material changes that altered the anisotropy of the valve were found to profoundly alter valve function. The addition of blood flow and an experimentally driven microstructural description of mitral tissue represent significant advances in computational studies of the mitral valve, which allow further insight to be gained. This work is another building block in the foundation of a computational framework to aid in the refinement and development of a truly non-invasive diagnostic evaluation of the mitral valve. Ultimately, it represents the basis for simulation of surgical repair of pathological valves in a clinical and educational setting.

Wavelet analysis of bileaflet mechanical valve sounds

It has been reported that asynchronous leaflet closure in a bileaflet mechanical valve causes a split in the valve closing sound. We have previously reported that the continuous wavelet transform (CWT) with the Morlet wavelet as modified by Ishikawa (the Morlet wavelet) is the most suitable method among the CWTs for detecting a split in the bileaflet mechanical valve sound because this method can detect the highest frequency signal among the CWT methods with higher time resolution. This is the first article which discusses the acoustic properties of five types of bileaflet valves using the Morlet CWT. Similar behavior of the valve sound split intervals with wide fluctuations over consecutive heartbeats was found to be the common finding for all the bileaflet valves. This result suggests that fluctuation of the split interval proves the normal movement of both leaflets without movement disturbance. The mean differences in the split interval between these bileaflet valves were statistically significant, and the wavelet coefficients of the CWT showed characteristic scalographic patterns, such as a teardrop shape or a triangle beneath the split. However, these two findings gave no valuable information for the diagnosis of bileaflet valve malfunction. A split in the valve closing sound with a fluctuating interval was the common finding in these five normally functioning bileaflet valves, and careful observation of the split's behavior may be a key to diagnosis of bileaflet valve malfunction.

Severe Acute Aortic Regurgitation due to Aortic Dissection

CASE DESCRIPTION Aortic insufficiency (AI) occurs frequently in patients with acute Type A aortic dissection. Exacerbation of this AI due to prolapse of the dissection flap is rare (1). A 68-year-old man presented to an outside hospital with sudden onset of severe back pain and numbness in his right leg. A Stanford Type A thoracic aortic dissection was diagnosed by a computed tomography scan. He was transferred via helicopter to our hospital for emergency aortic surgery. To expedite the care of this patient, he was transported directly to the operating room from the helipad. After induction of general anesthesia, transesophageal echocardiography (TEE) confirmed the diagnosis of an ascending aortic aneurysm with a dissection in the ascending aorta that progressed through the aortic arch into the distal descending aorta. In the midesophageal long axis view of the aorta, a definite, undulating dissection flap was seen as a mobile echogenic structure with a pattern of motion different than the aortic wall. Color flow imaging revealed an entry site into the false lumen in the ascending aorta and demonstrated blood flow in both the true and false lumens. The aortic valve was trileaflet. Color Doppler revealed severe AI because of incomplete leaflet closure from a dilated sinotubular junction. This AI was exacerbated by the back and forth movement of the dissection flap from the ascending aorta into the left ventricular outflow tract, further preventing coaptation of the aortic valve leaflets (Fig. 1). The midesophageal short axis view of the ascending aorta revealed a starfish-like appearance of the circumferential dissection flap (Fig. 2). In our patient, although it was not clear if the dissection involved the coronary arteries, both the left and right ventricles were normal in size and function, with no regional wall motion abnormalities. (TEE video loops are available online at www.anesthesia-analgesia.org.) The patient was placed on cardiopulmonary bypass and his ascending aorta and aortic valve were replaced with a 25-mm Carboseal valve conduit with reimplantation of the coronary arteries. Circulatory arrest under deep hypothermia was used for a portion of the procedure. TEE examination after weaning from cardiopulmonary bypass revealed a mechanical aortic valve prosthesis functioning normally and an ascending aortic graft with no evidence of leak. The dissection flap now seen in the aortic arch continued into the descending thoracic aorta. The patient was discharged home on the eighth day in satisfactory condition.

Functional mitral regurgitation in heart failure

Mitral regurgitation commonly occurs in patients with heart failure. Systolic dysfunction is the hallmark of dilated cardiomyopathy. Mitral functional regurgitation is mitral incompetence in the absence of intrinsic lesions of the mitral valve apparatus. Echocardiography can make a major contribution to the diagnosis of cardiomyopathies. A more careful anatomic and hemodynamic evaluation of mitral regurgitation mechanisms is possible with spectral Doppler, color Doppler, three-dimensional echocardiography and transesophageal echocardiography. Functional mitral regurgitation is due to the incomplete closure of mitral leaflets and is based on alterations of mitral annulus, left ventricular dimensions, function and geometry, left atrial dimensions and function. Knowledge of the mechanisms of mitral regurgitation helps us to gain an insight into therapeutic interventions that modify the mechanistic factors. Medical therapy reduces the tethering forces and also augments transmitral pressure; surgical approaches can modify geometric relationships in the left ventricular chamber and resynchronization therapy can improve co-ordinated timing of mechanical activation of papillary muscles.

Intraventricular Dyssynchrony May Play a Role in the Development of Mitral Regurgitation in Dilated Cardiomyopathy

Background The development of functional mitral regurgitation (MR) in dilated cardiomyopathy (DCM) has been attributed to altered left ventricular (LV) geometry and annular dilatation. We propose the hypothesis that intraventricular dyssynchrony may play a role in the development of MR in DCM. Methods and Results Tissue Doppler echocardiography was performed in 32 DCM patients to assess the time from the onset of the QRS complex to the peak systolic myocardial strain (Ts) at 2 segments adjacent to the anterolateral and posteromedial papillary muscles from a short axis view. The time difference corrected by the RR interval (ΔTs/√RR) was used to evaluate dyssynchrony of these segments. There was no difference in the QRS duration (103 ± 29 ms versus 95 ± 22 ms, P = .38) or the presence of left bundle branch block (39% versus 14 %, P = .25) between 18 patients with MR and 14 patients without MR. However, ΔTs/√RR was significantly increased in the patients with MR, compared with those without MR (104 ± 67 ms versus 5 ± 16 ms, P < .0001). Stepwise multiple regression analysis showed that ΔTs/√RR was independent contributing factor of MR. Conclusion Dyssynchrony of myocardial segments adjacent to the papillary muscles may disturb synchronized closure of the mitral leaflets and cause MR in DCM.

An Experimental Study of Steady Flow Patterns of a New Trileaflet Mechanical Aortic Valve

Hemodynamic research shows that thrombosis formation is closely tied to flow field turbulent stress. Design limitations cause flow separation at leaflet edges and the annular valve base, vortex mixing downstream, and high turbulent shear stress. The trileaflet design opens like a physiologic valve with central flow. Leaflet curvature approximates a completely circular orifice, maximizing effective flow area of the open valve. Semicircular aortic sinuses downstream of the valve allow vortex formation to help leaflet closure. The new trileaflet design was hemodynamically evaluated via digital particle image velocimetry and laser-Doppler anemometry. Measurements were made during peak flow of the fully open valve, immediately downstream of the valve, and compared with the 27-mm St. Jude Medical (SJM) bileaflet valve. The trileaflet valve central flow produces sufficient pressure to inhibit separation shear layers. Absence of downstream turbulent wake eddies indicates smooth, physiologic blood flow. In contrast, SJM produces strong turbulence because of unsteady separated shear layers where the jet flow meets the aortic sinus wall, resulting in higher turbulent shear stresses detrimental to blood cells. The trileaflet valve simulates the physiologic valve better than previous designs, produces smoother flow, and allows large scale recirculation in the aortic sinuses to help valve closure.

Lumped Parameter Model for Computing the Minimum Pressure During Mechanical Heart Valve Closure

The cavitation inception threshold of mechanical heart valves has been shown to be highly variable. This is in part due to the random distribution of the initial and final conditions that characterize leaflet closure. While numerous hypotheses exist explaining the mechanisms of inception, no consistent scaling laws have been developed to describe this phenomenon due to the complex nature of these dynamic conditions. Thus in order to isolate and assess the impact of these varied conditions and mechanisms on inception, a system of ordinary differential equations is developed to describe each system component and solved numerically to predict the minimum pressure generated during valve closure. In addition, an experiment was conducted in a mock circulatory loop using an optically transparent size 29 bileaflet valve over a range of conditions to calibrate and validate this model under physiological conditions. High-speed video and high-response pressure measurements were obtained simultaneously to characterize the relationship between the valve motion, fluid motion, and negative pressure transients during closure. The simulation model was calibrated using data from a single closure cycle and then compared to other experimental flow conditions and to results found in the literature. The simulation showed good agreement with the closing dynamics and with the minimum pressure trends in the current experiment. Additionally, the simulation suggests that the variability observed experimentally (when using dP/dt alone as the primary measure of cavitation inception) is predictable. Overall, results from the current form of this lumped parameter model indicate that it is a good engineering assessment tool.