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Lakshmi Prasad Dasi - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Left and Right Coronary Flow Waveforms on Aortic Sinus Hemodynamics and Leaflet Shear Stress: Correlation with Calcification Locations
    Annals of Biomedical Engineering, 2020
    Co-Authors: Dorma C. Flemister, Hoda Hatoum, Varshini Guhan, Banafsheh Zebhi, Joy Lincoln, Juan Crestanello, Lakshmi Prasad Dasi
    Abstract:

    Coronary flow induces hemodynamic alterations in the Aortic Sinus region. The objectives of this study are to: (1) investigate the differences among Sinus hemodynamics and leaflet wall shear stresses engendered by the left versus right versus non-coronary flow and (2) correlate respective wall shear stresses with leaflet calcification in patients. A left heart simulator flow loop with a tunable coronary circuit provided physiological coronary flow waveforms corresponding to the left coronary cusp case (LCC), right coronary cusp case (RCC), and non-coronary cusp case (NCC). High spatio-temporal resolution particle image velocimetry was conducted to quantify leaflet wall shear stress and Sinus vorticity fields and to measure Aortic leaflet tip kinematics. Thirty-one patients with severe calcific Aortic valve disease were segmented from CT data for the calcific volumes in their respective left, right, and non-coronary cusps. Leaflet tip position during systole shows the RCC has a wider leaflet opening compared to LCC and NCC. Velocity and vorticity fields combined with leaflet position data show that Sinus vorticity is diminished (peak ~ 43 s^−1) in the LCC while RCC and NCC maintain high vorticity (~ 1200 and ~ 950 s^−1 respectively). WSS magnitudes greater than 0.3 Pa show 20 and 81% greater occurrences in the LCC and RCC respectively compared to NCC. Significant differences [ X ^2 (2,  n = 31) = 7.31,  p  = 0.0258] between the calcification levels in each cusp of the patient population. Coronary flow differences between LCC, RCC, and NCC show significant impact on leaflet kinematics and Sinus flow hemodynamics. Clinical data correlations of the coronary flow cases indicate the left coronary cusp has a higher likelihood of calcification compared to the right.

  • spatiotemporal complexity of the Aortic Sinus vortex as a function of leaflet calcification
    Annals of Biomedical Engineering, 2019
    Co-Authors: Hoda Hatoum, Lakshmi Prasad Dasi
    Abstract:

    Several studies have shown the variation of Aortic Sinus structures' hemodynamics with different flow and geometric characteristics. They have also correlated Aortic Sinus hemodynamics with the progression and evolution of calcific Aortic valve disease (CAVD). This study aims at visualizing Aortic Sinus fluid structure variations as functions of different leaflet calcification degrees and assessing their potential relationship with CAVD. A degenerated 23 mm Carpentier-Edwards Perimount Magna valve extracted from a redo-surgery patient was implanted in an Aortic root model and tested in a pulse duplicator left heart simulator. The valve has 3 leaflets with 3 different levels of calcium distribution: mild, moderate and severe. High-speed imaging and particle image velocimetry were performed to assess Sinus vortices, leaflet tip position and velocity along with shear stress. Results have shown that (a) Aortic Sinus vortices initiation, entrapment and evolution varied with different calcified leaflet exposure; (b) higher velocities in the Sinus were calculated with the mildly calcified leaflet compared to the moderately and severely calcified ones; (c) during systole, the mildly calcified leaflet Sinus case shows the most spread-out and higher ranges of shear stress probabilities and highest magnitudes going from (- 1.5 to + 1.8 Pa) compared with (- 1.0 to + 1.0 Pa) for moderately and severely calcified leaflets. The higher the calcification degree the lower the shear stress range and likelihoods of having higher shear stress. This holds in diastole as well. This study shows the impact of calcification on the Aortic Sinus flow structures.

  • Aortic Sinus flow stasis likely in valve in valve transcatheter Aortic valve implantation
    The Journal of Thoracic and Cardiovascular Surgery, 2017
    Co-Authors: Hoda Hatoum, Brandon Moore, Pablo Maureira, Jennifer Dollery, Juan A Crestanello, Lakshmi Prasad Dasi
    Abstract:

    Abstract Objective Valve-in-valve procedures using transcatheter Aortic valves are increasingly performed to treat degenerated bioprosthetic surgical Aortic valves because they are less invasive than redo Aortic valve replacement. The objective of this study is to quantify the changes in Aortic Sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets. Methods A detailed description of the Sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical Aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter Aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary Sinuses in vitro. Results Velocity and vorticity within the surgical valve Sinuses reached peak values of 0.7 m/s and 1000 s −1 , with a 70% decrease in peak fluid shear stress near the Aortic side of the leaflet in the noncoronary Sinus. With the introduction of transcatheter Aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s −1 and 0.58 m/s and 653 s −1 without coronary flow and 0.60 m/s and 631 s −1 and 0.81 m/s and 669 s −1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the Aortic side of the coronary versus noncoronary transcatheter Aortic valve leaflet. Conclusions Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary Sinus.

  • coronary flow impacts Aortic leaflet mechanics and Aortic Sinus hemodynamics
    Annals of Biomedical Engineering, 2015
    Co-Authors: Brandon Moore, Lakshmi Prasad Dasi
    Abstract:

    Mechanical stresses on Aortic valve leaflets are well-known mediators for initiating processes leading to calcific Aortic valve disease. Given that non-coronary leaflets calcify first, it may be hypothesized that coronary flow originating from the ostia significantly influences Aortic leaflet mechanics and Sinus hemodynamics. High resolution time-resolved particle image velocimetry (PIV) measurements were conducted to map the spatiotemporal characteristics of Aortic Sinus blood flow and leaflet motion with and without physiological coronary flow in a well-controlled in vitro setup. The in vitro setup consists of a porcine Aortic valve mounted in a physiological aorta Sinus chamber with dynamically controlled coronary resistance to emulate physiological coronary flow. Results were analyzed using qualitative streak plots illustrating the spatiotemporal complexity of blood flow patterns, and quantitative velocity vector and shear stress contour plots to show differences in the mechanical environments between the coronary and non-coronary Sinuses. It is shown that the presence of coronary flow pulls the classical Sinus vorticity deeper into the Sinus and increases flow velocity near the leaflet base. This creates a beneficial increase in shear stress and washout near the leaflet that is not seen in the non-coronary Sinus. Further, leaflet opens approximately 10% farther into the Sinus with coronary flow case indicating superior valve opening area. The presence of coronary flow significantly improves leaflet mechanics and Sinus hemodynamics in a manner that would reduce low wall shear stress conditions while improving washout at the base of the leaflet.

  • Spatiotemporal complexity of the Aortic Sinus vortex
    Experiments in Fluids, 2014
    Co-Authors: Brandon Moore, Lakshmi Prasad Dasi
    Abstract:

    The Aortic Sinus vortex is a classical flow structure of significant importance to Aortic valve dynamics and the initiation and progression of calcific Aortic valve disease. We characterize the spatiotemporal characteristics of Aortic Sinus vortex dynamics in relation to the viscosity of blood analog solution as well as heart rate. High-resolution time-resolved (2 kHz) particle image velocimetry was conducted to capture 2D particle streak videos and 2D instantaneous velocity and streamlines along the Sinus midplane using a physiological but rigid aorta model fitted with a porcine bioprosthetic heart valve. Blood analog fluids used include a water–glycerin mixture and saline to elucidate the sensitivity of vortex dynamics to viscosity. Experiments were conducted to record 10 heart beats for each combination of blood analog and heart rate condition. Results show that the topological characteristics of the velocity field vary in timescales as revealed using time bin-averaged vectors and corresponding instantaneous streamlines. There exist small timescale vortices and a large timescale main vortex. A key flow structure observed is the counter vortex at the upstream end of the Sinus adjacent to the base (lower half) of the leaflet. The spatiotemporal complexity of vortex dynamics is shown to be profoundly influenced by strong leaflet flutter during systole with a peak frequency of 200 Hz and peak amplitude of 4 mm observed in the saline case. While fluid viscosity influences the length and timescales as well as the introduction of leaflet flutter, heart rate influences the formation of counter vortex at the upstream end of the Sinus. Higher heart rates are shown to reduce the strength of the counter vortex that can greatly influence the directionality and strength of shear stresses along the base of the leaflet. This study demonstrates the impact of heart rate and blood analog viscosity on Aortic Sinus hemodynamics.

Feifan Ouyang - One of the best experts on this subject based on the ideXlab platform.

  • response to letter from yamada and kay regarding article ventricular arrhythmias arising from the left ventricular outflow tract below the Aortic Sinus cusps mapping and catheter ablation via transseptal approach and electrocardiographic characterist
    Circulation-arrhythmia and Electrophysiology, 2014
    Co-Authors: Feifan Ouyang, Shibu Mathew, Masashi Kamioka, Andreas Metzner, Yumei Xue, Bing Yang, Xianzhang Zhan, Andreas Rillig, Tina Lin, Peter Rausch
    Abstract:

    We thank Drs Yamada and Kay for their comments regarding our article “Ventricular arrhythmias arising from the left ventricular outflow tract below the Aortic Sinus cusps: mapping and catheter ablation via transseptal approach and electrocardiographic characteristics.”1 The main issues raised by Drs Yamada and Kay focused around the transseptal approach used in our study to obtain better access to the area termed the LV summit. We agree with the authors that using the retrograde Aortic approach and with the catheter inversion technique, some of the regions beneath the Aortic Sinus cusps (ASC) can be reached. However, when this is performed with the 3D mapping system, one can see that in the majority of the time, there is a distance between …

  • catheter ablation of anteroseptal accessory pathway in the non coronary Aortic Sinus
    Europace, 2006
    Co-Authors: He Huang, Feifan Ouyang, Xingxiang Wang, Matthias Antz
    Abstract:

    We report a patient with atrioventricular reentrant tachycardia (AVRT) with bidirectional conduction over an anteroseptal accessory pathway (AP) who underwent successful ablation in the non-coronary Aortic Sinus (AS). In three previous attempts, the intracardiac recordings showed an anteroseptal AP with antegrade and retrograde conduction that failed to be ablated in spite of radiofrequency (RF) applications from the right and left anteroseptal regions. During the study, the earliest atrial activation during tachycardia was recorded in the non-coronary AS preceding the atrial activation at the His bundle (HB) region by 24 ms, and the anteroseptal AP was successfully blocked by one single ablation in the non-coronary AS. These data strongly suggest that careful mapping of an anteroseptal AP in the non-coronary AS may provide an alternative ablation approach in patients with previously failed ablation.

  • focal atrial tachycardia originating from the non coronary Aortic Sinus electrophysiological characteristics and catheter ablation
    Journal of the American College of Cardiology, 2006
    Co-Authors: Feifan Ouyang, Sabine Ernst, He Huang, Dietmar Bansch, Boris Schmidt, Karlheinz Kuck, Shaowen Liu, Min Chen, Julian Chun, Yunlong Xia
    Abstract:

    Objectives We sought to investigate electrophysiological characteristics and catheter ablation in patients with focal atrial tachycardia (AT) originating from the non-coronary Aortic Sinus (AS). Background In patients with failed ablation of focal AT near the His bundle (HB) region, an origin from the non-coronary AS should be considered because of the close anatomical relationship. Methods This study included 9 patients with focal AT, in 6 of whom attempted radiofrequency (RF) ablation had previously failed. Activation mapping was performed during tachycardia to identify an earliest activation in the atria and the AS. The Aortic root angiography was performed to identify the origin in the AS before RF ablation. Results Focal AT was reproducibly induced by atrial pacing. Mapping in atria demonstrated that the earliest atrial activation was located at the HB region, whereas mapping in the non-coronary AS demonstrated that an earliest atrial activation preceded the atrial activation at the HB by 12.2 ± 6.9 ms and was anatomically located superoposterior to the HB in all 9 patients. Also, His potentials were not found at the successful site in the non-coronary AS in all 9 patients. The focal AT was terminated in Conclusions In patients with focal AT near the HB region, mapping in the non-coronary AS can improve clinical outcome.

  • Repetitive monomorphic ventricular tachycardia originating from the Aortic Sinus cusp: electrocardiographic characterization for guiding catheter ablation.
    Journal of the American College of Cardiology, 2002
    Co-Authors: Feifan Ouyang, Parwis C. Fotuhi, Joachim Hebe, Masahiko Goya, Marius Volkmer, Sabine Ernst, Matthias Antz, Mark Burns, Siew Yen Ho, Riccardo Cappato
    Abstract:

    Abstract Objectives We sought to investigate the electrocardiographic (ECG) characteristics for guiding catheter ablation in patients with repetitive monomorphic ventricular tachycardia (RMVT) originating from the Aortic Sinus cusp (ASC). Background Repetitive monomorphic ventricular tachycardia can originate from the right ventricular outflow tract (RVOT) and ASC in patients with a left bundle branch block (LBBB) morphology and an inferior axis. Methods Activation mapping and ECG analysis was performed in 15 patients with RMVT or ventricular premature contractions. The left main coronary artery (LMCA) was cannulated as a marker and for protection during radiofrequency delivery if RMVT originated from the left coronary ASC. Results During arrhythmia, the earliest ventricular activation was recorded from the superior septal RVOT in eight patients (group 1) and from the ASC in the remaining seven patients (group 2). The indexes of R-wave duration and R/S-wave amplitude were significantly lower in group 1 than in group 2 (31.8 ± 13.5% vs. 58.3 ± 12.1% and 14.9 ± 9.9% vs. 56.7 ± 29.5%, respectively; p Conclusions On the surface ECG, RMVT from the ASC has a QRS morphology similar to that of RVOT arrhythmias. The indexes of R-wave duration and R/S-wave amplitude can be used to differentiate between the two origins. Radiofrequency ablation can be safely performed within the left ASC with a catheter cannulating the LMCA.

Gaetano Thiene - One of the best experts on this subject based on the ideXlab platform.

  • clinical profile of congenital coronary artery anomalies with origin from the wrong Aortic Sinus leading to sudden death in young competitive athletes
    Journal of the American College of Cardiology, 2000
    Co-Authors: Cristina Basso, Domenico Corrado, Barry J Maron, Gaetano Thiene
    Abstract:

    Abstract OBJECTIVES The purpose of this study is to characterize the clinical profile and identify clinical markers that would enable the detection during life of anomalous coronary artery origin from the wrong Aortic Sinus (with course between the aorta and pulmonary trunk) in young competitive athletes. BACKGROUND Congenital coronary artery anomalies are not uncommonly associated with sudden death in young athletes, the catastrophic event probably provoked by myocardial ischemia. Such coronary anomalies are rarely identified during life, often because of insufficient clinical suspicion. However, since anomalous coronary artery origin is amenable to surgical treatment, timely clinical identification is crucial. METHODS Because of the paucity of available data characterizing the clinical profile of wrong Sinus coronary artery malformations, we reviewed two large registries comprised of young competitive athletes who died suddenly, assembled consecutively in the U.S. and Italy. RESULTS We reported 27 sudden deaths in young athletes, identified solely at autopsy and due to either left main coronary artery from the right Aortic Sinus (n = 23) or right coronary artery from the left Sinus (n = 4). Each athlete died either during (n = 25) or immediately after (n = 2) intense exertion on the athletic field. Fifteen athletes (55%) had no clinical cardiovascular manifestations or testing during life. However, in the remaining 12 athletes (45%) aged 16 ± 7, certain clinical data were available. Premonitory symptoms had occurred in 10, including syncope in four (exertional in three and recurrent in two, 3 to 24 months before death) and chest pain in five (exertional in three, all single episodes, ≤24 months before death). All cardiovascular tests were within normal limits, including 12-lead electrocardiogram (ECG) pattern (in 9/9), stress ECG with maximal exercise (in 6/6) and left ventricular wall motion and cardiac dimensions by two-dimensional echocardiography (in 2/2). CONCLUSIONS With regard to congenital coronary artery anomalies of wrong Aortic Sinus origin in young competitive athletes, 1) standard testing with ECG under resting or exercise conditions is unlikely to provide clinical evidence of myocardial ischemia and would not be reliable as screening tests in large athletic populations, 2) premonitory cardiac symptoms not uncommonly occurred shortly before sudden death (typically associated with anomalous left main coronary artery), suggesting that a history of exertional syncope or chest pain requires exclusion of this anomaly. These observations have important implications for the preparticipation screening of competitive athletes.

  • anomalous origin of coronary arteries and risk of sudden death a study based on an autopsy population of congenital heart disease
    Human Pathology, 1998
    Co-Authors: Carla Frescura, Domenico Corrado, Tommaso Pennelli, Gaetano Thiene, Cristina Basso, Annalisa Angelini, Luciano Daliento
    Abstract:

    Coronary arteries anomalies may be part of complex congenital malformations of the heart or be an isolated defect. In our anatomic collection of congenital heart disease, an isolated anomalous origin of coronary arteries was observed in 27 of 1,200 specimens (2.2%): left coronary artery from pulmonary trunk in five, origin from the wrong Aortic Sinus in 12 (both right and left coronary artery from the right Sinus in four and from the left Sinus in seven, left coronary artery from the posterior Sinus in one), left circumflex branch from right Aortic Sinus or from very proximal right coronary artery in three, high takeoff of right coronary artery in three, stenosis of the coronary ostia attributable to valvelike ridge in four. In 16 (59%) patients (12 males and 4 females, age ranging from 2 months to 53 years; median, 14), the final outcome was sudden death; it occurred in all cases of left coronary artery origin from right Aortic Sinus, in 43% of right coronary artery origin from left Aortic Sinus, and in 40% of the left coronary artery from the pulmonary trunk. Sudden death was precipitated by effort in eight (50%) and was the first manifestation of the disease in eight (50%); previous symptoms consisted of recurrent syncope in four, palpitations in three, and chest pain in one. Five patients who died suddenly during effort were athletes. In conclusion, (1) more than half of our postmortem cases with anomalous origin of coronary arteries died suddenly, (2) all but two patients with sudden death had anomalous coronary artery origin from the aorta itself, (3) the fatal event was frequently precipitated by effort, (4) palpitations, syncope, and ventricular arrhythmias were the only prodromic symptoms and signs. Recognition during life of these coronary anomalies, by the use of noninvasive procedures, is mandatory to prevent the risk of sudden death and to plan surgical correction if clinically indicated.

  • anomalous origin of the left circumflex coronary artery from the right Aortic Sinus of valsalva and sudden death
    Cardiovascular Pathology, 1994
    Co-Authors: Domenico Corrado, Tommaso Pennelli, Piergiuseppe Piovesana, Gaetano Thiene
    Abstract:

    Anomalous origin of the left circumflex coronary artery from the right Aortic Sinus is generally considered a benign condition. We report a 53-year-old man with clinical and pathologic evidence of myocardial infarction and sudden death in the setting of this anomaly, with no evidence of obstructive coronary atherosclerosis.

Hoda Hatoum - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Left and Right Coronary Flow Waveforms on Aortic Sinus Hemodynamics and Leaflet Shear Stress: Correlation with Calcification Locations
    Annals of Biomedical Engineering, 2020
    Co-Authors: Dorma C. Flemister, Hoda Hatoum, Varshini Guhan, Banafsheh Zebhi, Joy Lincoln, Juan Crestanello, Lakshmi Prasad Dasi
    Abstract:

    Coronary flow induces hemodynamic alterations in the Aortic Sinus region. The objectives of this study are to: (1) investigate the differences among Sinus hemodynamics and leaflet wall shear stresses engendered by the left versus right versus non-coronary flow and (2) correlate respective wall shear stresses with leaflet calcification in patients. A left heart simulator flow loop with a tunable coronary circuit provided physiological coronary flow waveforms corresponding to the left coronary cusp case (LCC), right coronary cusp case (RCC), and non-coronary cusp case (NCC). High spatio-temporal resolution particle image velocimetry was conducted to quantify leaflet wall shear stress and Sinus vorticity fields and to measure Aortic leaflet tip kinematics. Thirty-one patients with severe calcific Aortic valve disease were segmented from CT data for the calcific volumes in their respective left, right, and non-coronary cusps. Leaflet tip position during systole shows the RCC has a wider leaflet opening compared to LCC and NCC. Velocity and vorticity fields combined with leaflet position data show that Sinus vorticity is diminished (peak ~ 43 s^−1) in the LCC while RCC and NCC maintain high vorticity (~ 1200 and ~ 950 s^−1 respectively). WSS magnitudes greater than 0.3 Pa show 20 and 81% greater occurrences in the LCC and RCC respectively compared to NCC. Significant differences [ X ^2 (2,  n = 31) = 7.31,  p  = 0.0258] between the calcification levels in each cusp of the patient population. Coronary flow differences between LCC, RCC, and NCC show significant impact on leaflet kinematics and Sinus flow hemodynamics. Clinical data correlations of the coronary flow cases indicate the left coronary cusp has a higher likelihood of calcification compared to the right.

  • spatiotemporal complexity of the Aortic Sinus vortex as a function of leaflet calcification
    Annals of Biomedical Engineering, 2019
    Co-Authors: Hoda Hatoum, Lakshmi Prasad Dasi
    Abstract:

    Several studies have shown the variation of Aortic Sinus structures' hemodynamics with different flow and geometric characteristics. They have also correlated Aortic Sinus hemodynamics with the progression and evolution of calcific Aortic valve disease (CAVD). This study aims at visualizing Aortic Sinus fluid structure variations as functions of different leaflet calcification degrees and assessing their potential relationship with CAVD. A degenerated 23 mm Carpentier-Edwards Perimount Magna valve extracted from a redo-surgery patient was implanted in an Aortic root model and tested in a pulse duplicator left heart simulator. The valve has 3 leaflets with 3 different levels of calcium distribution: mild, moderate and severe. High-speed imaging and particle image velocimetry were performed to assess Sinus vortices, leaflet tip position and velocity along with shear stress. Results have shown that (a) Aortic Sinus vortices initiation, entrapment and evolution varied with different calcified leaflet exposure; (b) higher velocities in the Sinus were calculated with the mildly calcified leaflet compared to the moderately and severely calcified ones; (c) during systole, the mildly calcified leaflet Sinus case shows the most spread-out and higher ranges of shear stress probabilities and highest magnitudes going from (- 1.5 to + 1.8 Pa) compared with (- 1.0 to + 1.0 Pa) for moderately and severely calcified leaflets. The higher the calcification degree the lower the shear stress range and likelihoods of having higher shear stress. This holds in diastole as well. This study shows the impact of calcification on the Aortic Sinus flow structures.

  • Aortic Sinus flow stasis likely in valve in valve transcatheter Aortic valve implantation
    The Journal of Thoracic and Cardiovascular Surgery, 2017
    Co-Authors: Hoda Hatoum, Brandon Moore, Pablo Maureira, Jennifer Dollery, Juan A Crestanello, Lakshmi Prasad Dasi
    Abstract:

    Abstract Objective Valve-in-valve procedures using transcatheter Aortic valves are increasingly performed to treat degenerated bioprosthetic surgical Aortic valves because they are less invasive than redo Aortic valve replacement. The objective of this study is to quantify the changes in Aortic Sinus blood flow dynamics before and after a valve-in-valve procedure to gain insight into mechanisms for clinical and subclinical thrombosis of leaflets. Methods A detailed description of the Sinus hemodynamics for valve-in-valve implantation was performed in vitro. A Medtronic Hancock II (Medtronic Inc, Minneapolis, Minn) porcine bioprosthesis was modeled as a surgical Aortic valve, and Medtronic CoreValve and Edwards Sapien (Edwards Lifesciences, Irvine, Calif) valves were used as the transcatheter Aortic valves. High-resolution particle image velocimetry was used to compare the flow patterns from these 2 valves within both the left coronary and noncoronary Sinuses in vitro. Results Velocity and vorticity within the surgical valve Sinuses reached peak values of 0.7 m/s and 1000 s −1 , with a 70% decrease in peak fluid shear stress near the Aortic side of the leaflet in the noncoronary Sinus. With the introduction of transcatheter Aortic valves, peak velocity and vorticity were reduced to approximately 0.4 m/s and 550 s −1 and 0.58 m/s and 653 s −1 without coronary flow and 0.60 m/s and 631 s −1 and 0.81 m/s and 669 s −1 with coronary flow for the CoreValve and Sapien valve-in-valve implantations, respectively. Peak shear stress was approximately 38% higher along the Aortic side of the coronary versus noncoronary transcatheter Aortic valve leaflet. Conclusions Decreased flow and shear stress in valve-in-valve procedures indicate a higher risk of leaflet thrombosis secondary to flow stasis, perhaps more so in the noncoronary Sinus.

Takumi Yamada - One of the best experts on this subject based on the ideXlab platform.

  • letter by yamada and kay regarding article ventricular arrhythmias arising from the left ventricular outflow tract below the Aortic Sinus cusps mapping and catheter ablation via transseptal approach and electrocardiographic characteristics
    Circulation-arrhythmia and Electrophysiology, 2014
    Co-Authors: Takumi Yamada, Neal G Kay
    Abstract:

    We read with great interest the most recent publication by Dr Ouyang et al1 on the transseptal approach in catheter ablation of ventricular arrhythmias (VAs) arising from the left ventricular outflow tract (LVOT) below the Aortic Sinus cusps (ASCs). We congratulate the authors for their interesting findings obtained during mapping and catheter ablation of VAs arising from the LVOT below the ASCs via an antegrade transseptal approach, although this approach was reported previously.2 We agree with the authors that mapping and catheter ablation in this region …

  • preferential conduction across the ventricular outflow septum in ventricular arrhythmias originating from the Aortic Sinus cusp
    Journal of the American College of Cardiology, 2007
    Co-Authors: Takumi Yamada, Naoki Yoshida, Yoshimasa Murakami, Taro Okada, Takeshi Shimizu, Junji Toyama, Yukihiko Yoshida, Naoya Tsuboi, Masahiro Muto, Yasuya Inden
    Abstract:

    Objectives The purpose of this study was to examine the relationship between the origin and breakout site of idiopathic ventricular tachycardia (VT) or premature ventricular contractions (PVCs) originating from the myocardium around the ventricular outflow tract. Background The myocardial network around the ventricular outflow tract is not well known. Methods We studied 70 patients with idiopathic VT (n = 23) or PVCs (n = 47) with a left bundle branch block and inferior QRS axis morphology. Electroanatomical mapping was performed in both the right ventricular outflow tract (RVOT) and Aortic Sinus cusp (ASC) during VT or PVCs. Results The earliest ventricular activation (EVA) was recorded in the RVOT in 55 patients (group R) and in the ASC in 15 (group A). In all group R patients, the closest pace map and successful ablation were achieved at the EVA site. Although a successful ablation was achieved at the EVA site in all group A patients, the closest pace map was obtained at the EVA site in 8 and RVOT in 7 (with an excellent pace map in 4). The stimulus to QRS interval was 0 ms during pacing from the RVOT and 36 ± 8 ms from the ASC. The distance between the EVA and perfect pace map sites in those 4 patients was 11.9 ± 3.0 mm. Conclusions Ventricular arrhythmias originating from the ASC often show preferential conduction to the RVOT, which may render pace mapping or some algorithms using the electrocardiographic characteristics less reliable. In some of those cases, an insulated myocardial fiber across the ventricular outflow septum may exist.