scholarly journals Non-invasive estimation of the mean pressure difference in aortic stenosis by Doppler ultrasound.

Heart ◽  
1986 ◽  
Vol 56 (5) ◽  
pp. 450-454 ◽  
Author(s):  
D Teien ◽  
K Karp ◽  
P Eriksson
Keyword(s):  
Aortic Stenosis ◽  
Doppler Ultrasound ◽  
Pressure Difference ◽  
Non Invasive ◽  
Mean Pressure ◽  
The Mean

scholarly journals Use and success evaluation of percutaneous aortic balloon valvuloplasty in different hemodynamic entities of severe aortic stenosis in the TAVR era

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
K Piayda ◽  
A Wimmer ◽  
H Sievert ◽  
K Hellhammer ◽  
S Afzal ◽  
...  
Keyword(s):  
Heart Failure ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Aortic Valve Replacement ◽  
Pressure Gradient ◽  
Severe Aortic Stenosis ◽  
Primary Treatment ◽  
Low Flow ◽  
Mean Pressure ◽  
The Mean

Abstract Background In the era of transcatheter aortic valve replacement (TAVR), there is renewed interest in percutaneous balloon aortic valvuloplasty (BAV), which may qualify as the primary treatment option of choice in special clinical situations. Success of BAV is commonly defined as a significant mean pressure gradient reduction after the procedure. Purpose To evaluate the correlation of the mean pressure gradient reduction and increase in the aortic valve area (AVA) in different flow and gradient patterns of severe aortic stenosis (AS). Methods Consecutive patients from 01/2010 to 03/2018 undergoing BAV were divided into normal-flow high-gradient (NFHG), low-flow low-gradient (LFLG) and paradoxical low-flow low-gradient (pLFLG) AS. Baseline characteristics, hemodynamic and clinical information were collected and compared. Additionally, the clinical pathway of patients (BAV as a stand-alone procedure or BAV as a bridge to aortic valve replacement) was followed-up. Results One-hundred-fifty-six patients were grouped into NFHG (n=68, 43.5%), LFLG (n=68, 43.5%) and pLFLG (n=20, 12.8%) AS. Underlying reasons for BAV and not TAVR/SAVR as the primary treatment option are displayed in Figure 1. Spearman correlation revealed that the mean pressure gradient reduction had a moderate correlation with the increase in the AVA in patients with NFHG AS (r: 0.529, p<0.001) but showed no association in patients with LFLG (r: 0.145, p=0.239) and pLFLG (r: 0.030, p=0.889) AS. Underlying reasons for patients to undergo BAV and not TAVR/SAVR varied between groups, however cardiogenic shock or refractory heart failure (overall 46.8%) were the most common ones. After the procedure, independent of the hemodynamic AS entity, patients showed a functional improvement, represented by substantially lower NYHA class levels (p<0.001), lower NT-pro BNP levels (p=0.003) and a numerical but non-significant improvement in other echocardiographic parameters like the left ventricular ejection fraction (p=0.163) and tricuspid annular plane systolic excursion (TAPSE, p=0.066). An unplanned cardiac re-admission due to heart failure was necessary in 23.7% patients. Less than half of the patients (44.2%) received BAV as a bridge to TAVR/SAVR (median time to bridge 64 days). Survival was significantly increased in patients having BAV as a staged procedure (log-rank p<0.001). Conclusion In daily clinical practice, the mean pressure gradient reduction might be an adequate surrogate of BAV success in patients with NFHG AS but is not suitable for patients with other hemodynamic entities of AS. In those patients, TTE should be directly performed in the catheter laboratory to correctly assess the increase of the AVA. BAV as a staged procedure in selected clinical scenarios increases survival and is a considerable option in all flow states of severe AS. (NCT04053192) Figure 1 Funding Acknowledgement Type of funding source: None

Abstract 17142: Long Term Results of Non-Invasive Ultrasound Therapy (NIUT) in Severe Symptomatic Aortic Valve Stenosis - First-in-Man

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Emmanuel Messas ◽  
Alexander Ijsselmuiden ◽  
Selina Vlieger ◽  
Peter den Heijer ◽  
Guillaume Goudot ◽  
...  
Keyword(s):  
Heart Failure ◽  
Aortic Valve ◽  
Aortic Stenosis ◽  
Pressure Gradient ◽  
Aortic Valve Stenosis ◽  
Long Term Results ◽  
Ultrasound Therapy ◽  
Non Invasive ◽  
Mean Pressure

Background: Not all patients with severe aortic valve stenosis are eligible for open-heart surgery or TAVR. CARDIAWAVE (Paris, France) has developed Valvosoft, a unique non-invasive ultrasound therapy device to treat aortic stenosis. The therapy aims to improve the opening of severely calcified aortic valves by cracking the calcium and reducing the stiffness in the aortic valve tissue by delivering transthoracically local shock waves on the valve leaflets. This study assesses the safety, feasibility and performance of this novel technique. Methods: This is a multi-center, prospective, first-in-man study designed to evaluate the safety and feasibility of the Valvosoft device. Ten patients with severe symptomatic calcific aortic stenosis and not eligible for SAVR/TAVR underwent a Valvosoft ultrasound therapy. Echocardiographic evaluation was performed by an independent core lab at baseline, discharge, and at 1, 3, 6 and 12 months along with clinical follow up. Results: Enrolled patients were advanced in age (84.1±6.5 yrs) with severe comorbidities (8 with heart failure, 5 with coronary heart disease and 5 with kidney failure). All had extensive aortic valve calcification with mean AVA of 0.61±0.17 cm2 and mean pressure gradient of 37.5±10.5 mmHg. At one-month follow-up, six patients had significantly improved their AVA with increase of 27.5% (p=0.03) and mean pressure gradient decrease of 23.2 % (p=0.025). These patients also received the highest dose and longest treatment duration. During one year follow up, 4 patients died due to progression of end stage heart failure not linked to the procedure and one patient had undergone a TAVR procedure. At 12 months, the five remaining patients has no device or procedure related major adverse events nor deterioration of neurological status. Echo, brain-MRI and clinical follow up will be presented. Conclusions: Non-invasive ultrasound therapy is feasible and safe in patients with severe aortic valve stenosis and can improve AVA and hemodynamic parameters. NIUT can be an important tool complementary to TAVI in treating patients with aortic valve stenosis.

scholarly journals Safety, feasibility and performance of Valvosoft non-invasive ultrasound therapy in patients with severe symptomatic calcific aortic valve stenosis. First-in-Man

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
E Messas ◽  
A Ijsselmuiden ◽  
G Goudot ◽  
S Vlieger ◽  
P Den Heijer ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Pressure Gradient ◽  
Ultrasound Therapy ◽  
Funding Source ◽  
Non Invasive ◽  
Post Procedure ◽  
Mean Pressure ◽  
Valve Opening ◽  
The Mean

Abstract Objectives We recently developed a unique transthoracic non-invasive ultrasound therapy device called Valvosoft to treat aortic stenosis. The therapy consists in delivering trans-thoracically precisely focused and controlled short ultrasound pulses (<20μsec) at a high acoustic intensity to produce non-thermal mechanical tissue softening of the calcified aortic valve with the ultimate aim of improving the valve opening. Ultrasound imaging enables to follow valve movements in real-time and thus targets the ultrasound waves on the valve with great precision. After having validated this concept in pre-clinical studies, we aimed at applying this technique in human. The primary objectives were to assess the safety and feasibility of this novel technique along with its performance by evaluation of the valve leaflets mobility and valve opening area. Methods This is a multi-center, prospective, controlled first-in-man study. Ten patients with severe symptomatic calcific aortic stenosis and not eligible for SAVR/TAVR underwent a Valvosoft ultrasound therapy. The therapy consists of 6 sessions of ultrasound therapy. The Valvosoft transducer is applied on the patient's chest and coupled at its center with an echocardiography phased array probe to allow real-time control of the therapy (cavitation bubble detection). Preselection of the region of interest is performed by echo still frame before each session. Ultrasonic evaluation was performed by an independent core lab at baseline, discharge, 30-day and 3 month follow-up along with clinical follow up. Results Enrolled patients were advanced in age (84.1±6.5 yrs) with severe comorbidities (8 with heart failure, 5 with coronary heart disease and 5 with kidney failure). All had extensive aortic valve calcification (mean calcification volume of 687.28 mm3) with mean AVA of 0.61±0.17 cm2 and mean pressure gradient of 37.5±10.5 mmHg (6 patients had SV<35ml/m2). No adverse events were recorded during the procedures other than some benign ventricular extrasystoles. The mean treatment time was 52 minutes. At 3 months follow-up, one patient had died due to end stage heart failure not linked to the procedure (9 weeks post procedure) and another got finally TAVI (45 days post procedure). Of the other 8 patients, 6 experienced an improvement of their NYHA status. No device or procedure related major adverse events nor deterioration of neurological status were observed at 3 months follow-up. Of the 7 patients that had echo follow-up at 3 months (one patient refused to get echo evaluation), 5 increased the AVA (between 14% and 46%) and 4 patients decreased the mean pressure gradient (from 6% to 44%). No AI or EF deterioration occurred during follow up. Conclusion Non-invasive ultrasound therapy is feasible and safe in patients with severe aortic valve stenosis and is able to improve AVA and pressure gradient in some patient. Larger studies with longer follow up will need to be conducted. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Cardiawave SA, Paris, France

SIMULATION OF A CLOSED LOOP MODEL EQUIVALENT ELECTRONIC OF NORMAL CARDIOVASCULAR SYSTEM AND VALVULAR AORTIC STENOSIS

2020 ◽  
Vol 20 (01) ◽  
pp. 1950074
Author(s):  
AMINA HALAIMI ◽  
BOUALEM CHETTI ◽  
BOUALEM LARIBI ◽  
OMAR LABBADLIA
Keyword(s):  
Aortic Stenosis ◽  
Pressure Gradient ◽  
Effective Orifice Area ◽  
Loop Model ◽  
Orifice Area ◽  
Electrical Analogy ◽  
Mean Pressure ◽  
Valvular Aortic Stenosis ◽  
The Mean ◽  
Good Agreement

This work presents a developed zero-dimensional cardiovascular (CV) system model, based on an electrical analogy, with a detailed compartmental description of the heart and the main vascular circulation which is able to simulate normal and diseased conditions of CV system, especially the stenosis valvular aortic. To know the effect of each parameter on hemodynamics, the number of parameters is increased by adding more segments. The developed model consists of 14 compartments. The results show that the severity of aortic stenosis (AS) effect varies with the effective orifice area and the mean pressure gradient for the case of no AS; the effective orifice area is 4[Formula: see text]cm2 and the mean pressure gradient is 0[Formula: see text]mmHg, while for the case of mild AS, the effective orifice area is 1.5[Formula: see text]cm2 and the mean pressure gradient is 27.24[Formula: see text]mmHg. For the case of moderate AS, the effective orifice area is 1.0[Formula: see text]cm2 and the mean pressure gradient is 44.68[Formula: see text]mmHg. For the case of the severe AS, the effective orifice area is 0.61[Formula: see text]cm2 and the mean pressure gradient is 77.51[Formula: see text]mmHg. It is found that the developed model can estimate an accurate value of the effective orifice area for any value of mean pressure gradient in AS. The results obtained for the CV system under normal and diseased conditions show a good agreement compared to published results.

scholarly journals Consequences of intravascular lymphatic valve properties: a study of contraction timing in a multi-lymphangion model

2016 ◽  
Vol 310 (7) ◽  
pp. H847-H860 ◽  
Author(s):  
Christopher D. Bertram ◽  
Charlie Macaskill ◽  
Michael J. Davis ◽  
James E. Moore
Keyword(s):  
Pressure Difference ◽  
Refractory Period ◽  
Ex Vivo ◽  
Lymphatic Vessels ◽  
Lymphatic Valve ◽  
Mean Pressure ◽  
In Series ◽  
The Mean ◽  
A Chain ◽  
Lymphatic Pumping

The observed properties of valves in collecting lymphatic vessels include transmural pressure-dependent bias to the open state and hysteresis. The bias may reduce resistance to flow when the vessel is functioning as a conduit. However, lymphatic pumping implies a streamwise increase in mean pressure across each valve, suggesting that the bias is then potentially unhelpful. Lymph pumping by a model of several collecting lymphatic vessel segments (lymphangions) in series, which incorporated these properties, was investigated under conditions of adverse pressure difference while varying the refractory period between active muscular contractions and the inter-lymphangion contraction delay. It was found that many combinations of the timing parameters and the adverse pressure difference led to one or more intermediate valves remaining open instead of switching between open and closed states during repetitive contraction cycles. Cyclic valve switching was reliably indicated if the mean pressure in a lymphangion over a cycle was higher than that in the lymphangion upstream, but either lack of or very brief valve closure could cause mean pressure to be lower downstream. Widely separated combinations of refractory period and delay time were found to produce the greatest flow-rate for a given pressure difference. The efficiency of pumping was always maximized by a long refractory period and lymphangion contraction starting when the contraction of the lymphangion immediately upstream was peaking. By means of an ex vivo experiment, it was verified that intermediate valves in a chain of pumping lymphangions can remain open, while the lymphangions on either side of the open valve continue to execute contractions.

scholarly journals Non-invasive assessment of aortic stenosis by Doppler ultrasound.

Heart ◽  
1980 ◽  
Vol 43 (3) ◽  
pp. 284-292 ◽  
Author(s):  
L Hatle ◽  
B A Angelsen ◽  
A Tromsdal
Keyword(s):  
Aortic Stenosis ◽  
Doppler Ultrasound ◽  
Non Invasive

scholarly journals Estimation of Seams in Paraglider Wing

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Paulina Maślanka ◽  
Ryszard Korycki ◽  
Halina Szafrańska
Keyword(s):  
Pressure Difference ◽  
Relative Elongation ◽  
Test Results ◽  
Physical Strength ◽  
Covering Material ◽  
Mean Pressure ◽  
Maximal Pressure ◽  
Flight Parameters ◽  
The Mean

AbstractThe aim of the article is to analyze the seams connecting the covering textiles in paraglider wing and estimate their physical strength. The most extreme flight parameters (the angle of attack and velocity) in the numerical model of the wing allow the determination of the mean pressure inside the contour and the maximal difference between the pressures on the inner and the outer material surfaces. The preprocessing stage and numerical calculations in Ansys environment consider three different covering materials. The tool Porous Media is used to create the objects of a given value of air permeability. The estimated parameter of seam is the maximal pressure difference between both sides of the covering material, which that interacts with the test results. The quality index of the seam is defined by the maximal force to seam rupture and relative elongation during rupture. The obtained results indicate that the seams are resistant to the pressure difference caused by the most extreme flight parameters.

Diagnosis of Deep Vein Thrombosis by Combination of Doppler Ultrasound Flow Examination and Strain Gauge Plethysmography

1982 ◽  
Vol 47 (02) ◽  
pp. 141-144 ◽  
Author(s):  
H Bounameaux ◽  
B Krähenbühl ◽  
S Vukanovic
Keyword(s):  
Deep Vein Thrombosis ◽  
Negative Predictive Value ◽  
Doppler Ultrasound ◽  
Strain Gauge ◽  
Predictive Value ◽  
Lower Limbs ◽  
Vein Thrombosis ◽  
Non Invasive ◽  
Strain Gauge Plethysmography ◽  
Deep Vein

SummaryDoppler ultrasound flow examination, strain gauge plethysmography and contrast venography were performed in 160 lower limbs of 80 in-patients. Deep vein thrombosis (DVT) was suspected in 87 limbs. Using measurement of venous stop-flow pressure, the Doppler method had an overall sensitivity of 83%. By combined use of Doppler and Plethysmography, sensitivity was increased to 96%. Specificity was 62% and 51%, respectively. With a positive and a negative predictive value of 80% and 73%, respectively, the combination of both non-invasive methods cannot reliably replace venography in the diagnosis of DTV, although all (40/40) thromboses proximal to or involving the popliteal segment were detected by either Doppler and Plethysmography or both.After exclusion of 14 patients (18%) suffering from conditions known to alter the results of these non-invasive methods, the positive predictive value of abnormal findings in both Doppler and Plethysmography was increased to 94% for suspected limbs, whilst negative predictive value of both negative Doppler and Plethysmography was 90%, allowing the avoidance of venography in these patients.

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