scholarly journals A left ventricular phantom for 3D echocardiographic twist measurements

2020 ◽  
Vol 65 (2) ◽  
pp. 209-218
Author(s):  
Johannes Just Hjertaas ◽  
Knut Matre
Keyword(s):  
Stroke Volume ◽  
Spatial Resolution ◽  
Reference Method ◽  
3D Ultrasound ◽  
Left Ventricular ◽  
Apical Rotation ◽  
Mock Circulation ◽  
Custom Made ◽  
Wide Range ◽  
2D Ultrasound

AbstractTraditional two-dimensional (2D) ultrasound speckle tracking echocardiography (STE) studies have shown a wide range of twist values, also for normal hearts, which is due to the limitations of short-axis 2D ultrasound. The same limitations do not apply to three-dimensional (3D) ultrasound, and several studies have shown 3D ultrasound to be superior to 2D ultrasound, which is unreliable for measuring twist. The aim of this study was to develop a left ventricular twisting phantom and to evaluate the accuracy of 3D STE twist measurements using different acquisition methods and volume rates (VR). This phantom was not intended to simulate a heart, but to function as a medium for ultrasound deformation measurement. The phantom was made of polyvinyl alcohol (PVA) and casted using 3D printed molds. Twist was obtained by making the phantom consist of two PVA layers with different elastic properties in a spiral pattern. This gave increased apical rotation with increased stroke volume in a mock circulation. To test the accuracy of 3D STE twist, both single-beat, as well as two, four and six multi-beat acquisitions, were recorded and compared against twist from implanted sonomicrometry crystals. A custom-made software was developed to calculate twist from sonomicrometry. The phantom gave sonomicrometer twist values from 2.0° to 13.8° depending on the stroke volume. STE software tracked the phantom wall well at several combinations of temporal and spatial resolution. Agreement between the two twist methods was best for multi-beat acquisitions in the range of 14.4–30.4 volumes per second (VPS), while poorer for single-beat and higher multi-beat VRs. Smallest offset was obtained at six-beat multi-beat at 17.1 VPS and 30.4 VPS. The phantom proved to be a useful tool for simulating cardiac twist and gave different twist at different stroke volumes. Best agreement with the sonomicrometer reference method was obtained at good spatial resolution (high beam density) and a relatively low VR. 3D STE twist values showed better agreement with sonomicrometry for most multi-beat recordings compared with single-beat recordings.

Left ventricular-arterial coupling in conscious dogs

1991 ◽  
Vol 261 (1) ◽  
pp. H70-H76 ◽  
Author(s):  
W. C. Little ◽  
C. P. Cheng
Keyword(s):  
Stroke Volume ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Arterial System ◽  
Conscious Dogs ◽  
Stroke Work ◽  
Arterial Elastance ◽  
Inotropic State ◽  
End Diastolic Volume ◽  
Wide Range

We investigated the criteria for the coupling of the left ventricle (LV) and the arterial system to maximize LV stroke work (SW) and the transformation of LV pressure-volume area (PVA) to SW. We studied eight conscious dogs that were instrumented to measure LV pressure and determine LV volume from three ultrasonically determined dimensions. The LV end-systolic pressure (PES)-volume (VES) relation was determined by caval occlusion. Its slope (EES) was compared with the arterial elastance (EA) and determined as PES per stroke volume. At rest, with intact reflexes, EES/EA was 0.96 +/- 0.20 EES/EA was varied over a wide range (0.18-2.59) by the infusion of graded doses of phenylephrine and nitroprusside before and during administration of dobutamine. Maximum LV SW, at constant inotropic state and end-diastolic volume (VED), occurred when EES/EA equaled 0.99 +/- 0.15. At constant VED and contractile state, SW was within 20% of its maximum value when EES/EA was between 0.56 and 2.29. The conversion of LV PVA to SW increased as EES/EA increased. The shape of the observed relations of the SW to EES/EA and SW/PVA to EES/EA was similar to that predicted by the theoretical consideration of LV PES-VES and arterial PES-stroke volume relations. We conclude that the LV and arterial system produce maximum SW at constant VED when EES and EA are equal; however, the relation of SW to EES/EA has a broad plateau. Only when EA greatly exceeds EES does the SW fall substantially. However, the conversion of PVA to SW increases as EES/EA increases. These observations support the utility of analyzing LV-arterial coupling in the pressure-volume plane.

Left ventricular stroke volume by single and dual excitation of conductance catheter in dogs

1993 ◽  
Vol 264 (6) ◽  
pp. H2198-H2207 ◽  
Author(s):  
P. Steendijk ◽  
E. T. Van der Velde ◽  
J. Baan
Keyword(s):  
Stroke Volume ◽  
Left Ventricular Volume ◽  
Ventricular Volume ◽  
Left Ventricular ◽  
Volume Estimation ◽  
Conductance Catheter ◽  
Homogeneous Electric Field ◽  
Conductance Method ◽  
Wide Range ◽  
Excitation Method

The conductance method employs a multielectrode catheter to measure intracavitary electric conductance from which left ventricular volume is estimated. A dual-excitation method introduced by us uses a more homogeneous electric field and thereby should enable more accurate volume estimation. In six anesthetized open-chest dogs we compared stroke volume obtained from electromagnetic flow probes with the conventional single-excitation method and with the new dual-excitation conductance method. Caval occlusion and left atrial hemorrhage were used to obtain a wide range of stroke volumes. The slope of the relation between stroke volume calculated from the flow probes and from the conductance catheter increased significantly (P < 0.001) from 0.635 with single excitation to 0.835 with dual excitation, but the interanimal variability was not reduced. The linearity of the relation was substantially improved.

Conductance catheter measurement of left ventricular volume: evidence for nonlinearity within cardiac cycle

1995 ◽  
Vol 268 (4) ◽  
pp. H1490-H1498 ◽  
Author(s):  
R. S. Szwarc ◽  
D. Laurent ◽  
P. R. Allegrini ◽  
H. A. Ball
Keyword(s):  
Stroke Volume ◽  
Cardiac Cycle ◽  
Time Derivative ◽  
Reference Method ◽  
Ventricular Volume ◽  
Left Ventricular ◽  
Conductance Catheter ◽  
Systolic Volume ◽  
End Diastolic Volume ◽  
End Systolic Volume

The conductance catheter gain factor, alpha, is usually determined by an independent measure of stroke volume and, as such, is assumed to be constant. However, nonlinearity of the conductance-volume relation has been proposed on theoretical grounds. The present study was designed to establish the extent of nonlinearity, or variability of alpha, within the cardiac cycle using magnetic resonance imaging (MRI) as the reference method. Pentobarbital-anesthetized minipigs (n = 10, 10–13 kg) were instrumented with left ventricular (LV) conductance and Millar catheters. Conductance catheter signals were recorded, and volumes were corrected for parallel conductance using a saline-dilution technique. Animals were then placed in a 4.7-T magnet, and first time derivative of LV pressure-gated transverse MRI images (5-mm slices) acquired during isovolumic contraction (end diastole) and relaxation (end systole). LV cavity volumes were then determined using a third-order polynomial model. The gain alpha was computed three ways: by dividing conductance stroke volume by MRI stroke volume (alpha SV), by dividing conductance end-diastolic volume by MRI end-diastolic volume (alpha ED), and by dividing conductance end-systolic volume by MRI end-systolic volume (alpha ES). alpha SV was 0.62 +/- 0.15, with alpha ED (0.71 +/- 0.17) significantly lower than alpha ES (0.81 +/- 0.21; P < 0.001). Using alpha SV to adjust conductance gain (i.e., assuming constant gain) resulted in a significantly larger end-diastolic volume (25.8 +/- 4.6 ml) and smaller ejection fraction (46.8 +/- 7.2%) than those obtained with MRI (23.0 +/- 4.1 ml and 53.1 +/- 7.3%, respectively; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of mechanical limitation of apical rotation on left ventricular relaxation and end-diastolic pressure

2011 ◽  
Vol 301 (4) ◽  
pp. H1456-H1460 ◽  
Author(s):  
Mariko Iwasaki ◽  
Kasumi Masuda ◽  
Toshihiko Asanuma ◽  
Satoshi Nakatani
Keyword(s):  
Stroke Volume ◽  
Diastolic Function ◽  
Diastolic Pressure ◽  
Radial Strain ◽  
Systolic Pressure ◽  
Left Ventricular ◽  
Suction Device ◽  
Relaxation Period ◽  
Apical Rotation ◽  
Pressure Peak

Left ventricular (LV) twist is thought to play an important role in cardiac function. However, how twist affects systolic or diastolic function is not understood in detail. We acquired apical and basal short-axis images of dogs undergoing open-chest procedures ( n = 15) using a GE Vivid 7 at baseline and during the use of an apical suction device (Starfish) to limit apical rotation. We measured LV pressure and stroke volume using a micromanometer-tipped catheter and an ultrasonic flow probe, respectively. Peak radial strain, peak rotation, peak twist, peak systolic twisting rate (TR), peak untwisting rate during isovolumic relaxation period (URIVR), and peak early diastolic untwisting rate after mitral valve opening (URE) were determined using speckle tracking echocardiography. Immobilizing the apex with gentle suction significantly decreased apical rotation (−50 ± 27%) and slightly increased basal rotation, resulting in a significant decrease in twist. The time constant of LV relaxation (τ) was prolonged, and LV end-diastolic pressure increased. TR and URIVR decreased. LV systolic pressure, peak positive and negative first derivative of LV pressure (±dP/d t), stroke volume, radial strain, and URE were not changed. The correlation between τ and URIVR ( r = 0.63, P = 0.0006) was stronger than that between peak +dP/d t and TR ( r = 0.46, P = 0.01). Diastolic function was impaired with reduced apical rotation and URIVR when the apex of the heart was immobilized using an apical suction device.

scholarly journals Differences in Left Ventricular Function at Rest and during Isometric Handgrip Exercise in Elite Swimmers, Water Polo Players, and Artistic Swimmers

2021 ◽  
Author(s):  
Alexandra M Coates ◽  
Christian P Cheung ◽  
Katharine D Currie ◽  
Trevor James King ◽  
Margo L Mountjoy ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Diastolic Function ◽  
Left Ventricular ◽  
Lv Function ◽  
Handgrip Exercise ◽  
Isometric Handgrip ◽  
Training Environment ◽  
Water Polo ◽  
Apical Rotation ◽  
Elite Swimmers

Purpose: Elite swimmers (SW) have reduced diastolic function compared to elite runners, possibly as an adaptation to the aquatic training environment. Water polo players (WP) and artistic swimmers (AS) are exposed to the same hydrostatic pressures as SW, but are subject to different training intensities, postures, and hemodynamic stressors. Our purpose was to compare resting and exercising cardiac function in elite SW, WP, and AS, to characterize the influence of training for aquatic-sport on left ventricular (LV) adaptation.Methods: Ninety athletes (SW:20M/17F; WP:21M/9F; AS:23F) at the 2019 FINA World Championships volunteered for resting and stress (3min 30% maximal isometric handgrip) echocardiographic assessment of LV global function and mechanics. Results: Male SW displayed improved resting systolic and diastolic function compared to WP; however, both groups maintained stroke volume under high-pressure handgrip stress (SW:∆-4±12%; WP:∆-1±13%, P=0.11). There were no differences between female SW and WP resting LV function, but SW demonstrated improved function over AS. During isometric handgrip, all female sport athletes maintained stroke volume (SW:∆3±16%; WP:∆-10±11%; AS:∆-2±14%, P=0.46), but WP had improved apical rotation (∆1.7±4.5°), which was reduced in AS (∆-3.1±4.5°) and maintained in SW (∆-0.5±3.8°, P=0.04). Unlike SW and WP, AS displayed a unique maintenance of early filling velocity during handgrip exercise (SW:∆-3.5±14.7cm/s; WP:∆-15.1±10.8cm/s; AS:∆1.5±15.3cm/s, P=0.02).Conclusion: Among male athletes, SW display primarily volume-based functional adaptations distinct from the mixed volume-pressure adaptations of WP; however, both groups can maintain stroke volume with increased afterload. Female SW and WP do not demonstrate sport-specific differences like males, perhaps owing to sex-differences in adaptation, but have greater volume-based adaptations than AS. Lastly, AS display unique functional adaptations, that may be driven by elevated pressures under low-volume conditions.

scholarly journals High frame rate speckle tracking echocardiography to assess diastolic function

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
K Papangelopoulou ◽  
M Orlowska ◽  
S Bezy ◽  
A Petrescu ◽  
A Werner ◽  
...  
Keyword(s):  
Diastolic Function ◽  
Temporal Resolution ◽  
Speckle Tracking ◽  
Reference Method ◽  
Left Ventricular ◽  
Frame Rate ◽  
Doppler Imaging ◽  
Diastolic Filling ◽  
High Frame Rate ◽  
Custom Made

Abstract Background Left ventricular (LV) strain rate (SR) during isovolumic relaxation (SRIVR) and early diastolic filling (SRe) has previously been shown to correlate with the invasive gold standard for LV diastolic function (i.e. the time constant of LV pressure decay tau). However, the translation of these biomarkers to the clinic has been hampered by technical limitations. Indeed, conventional speckle tracking (STE) is limited by its temporal resolution, whereas tissue Doppler imaging (TDI) is angle-dependent, labor-intensive and thus rarely used clinically nowadays. Purpose The aim of this study was to show that these limitations could be overcome by using a recently proposed STE algorithm operating on high frame rate (HFR) imaging data. Methods 37 subjects (age: 64±12, 81% male) were included in the study; 16 had cardiac amyloidosis, 12 were undergoing clinically indicated left and/or right heart cardiac catheterization and 9 were healthy volunteers. Since the sequence of left ventricular activation and thus the repolarization process (i.e. relaxation) starts at mid septum, we measured SRIVR and SRe in the mid septal segment in an apical 4 chamber view using a commercially available clinical system with: (1) TDI (frame rate (FR) ∼142 Hz); (2) STE (FR ∼65 Hz). Moreover, subjects were scanned with HD-PULSE, an experimental high frame ultrasound scanner (FR ∼915 Hz) and then a manually placed contour was tracked during the cardiac cycle by a custom-made 2D HFR STE algorithm, to compute and extract SRIVR and SRe from the mid septum. Since TDI is considered the reference method to assess SR, conventional as well as HFR STE values were correlated against the TDI SR values. Results In 3 subjects, SRIVR could not be reliably assessed with the clinical STE approach, which we attributed to the relatively low temporal resolution of the images; all other measurements could be made in all subjects. For both biomarkers, HFR STE values correlated better with the TDI reference measurements than the clinical STE estimates (Fig.1). The latter estimates showed a systematic underestimation (bias −0.19 1/s (p&lt;0.01) and −0.46 1/s (p&lt;0.01) for SRIVR and SRe respectively) while no significant bias was observed for the HFR STE values. Similarly, the limits of agreement of the HFR STE values were narrower (−0.45 to +0.54 1/s and −0.94 to +0.86 1/s) than those of the clinical STE measurements (−0.85 to +0.48 1/s and −1.32 to +0.41 1/s). Conclusions These results show that HFR STE offers a reliable way to assess novel biomarkers of diastolic function in a user-friendly manner and can therefore facilitate their incorporation to the clinical practice. FUNDunding Acknowledgement Type of funding sources: None.

scholarly journals Impaired myocardial function does not explain reduced left ventricular filling and stroke volume at rest or during exercise at high altitude

2015 ◽  
Vol 119 (10) ◽  
pp. 1219-1227 ◽  
Author(s):  
Mike Stembridge ◽  
Philip N. Ainslie ◽  
Michael G. Hughes ◽  
Eric J. Stöhr ◽  
James D. Cotter ◽  
...  
Keyword(s):  
Stroke Volume ◽  
High Altitude ◽  
Systolic Function ◽  
Left Ventricular ◽  
Limiting Factor ◽  
End Diastolic Volume ◽  
Apical Rotation ◽  
Diastolic Relaxation ◽  
Ventricular Filling

Impaired myocardial systolic contraction and diastolic relaxation have been suggested as possible mechanisms contributing to the decreased stroke volume (SV) observed at high altitude (HA). To determine whether intrinsic myocardial performance is a limiting factor in the generation of SV at HA, we assessed left ventricular (LV) systolic and diastolic mechanics and volumes in 10 healthy participants (aged 32 ± 7; mean ± SD) at rest and during exercise at sea level (SL; 344 m) and after 10 days at 5,050 m. In contrast to SL, LV end-diastolic volume was ∼19% lower at rest ( P = 0.004) and did not increase during exercise despite a greater untwisting velocity. Furthermore, resting SV was lower at HA (∼17%; 60 ± 10 vs. 70 ± 8 ml) despite higher LV twist (43%), apical rotation (115%), and circumferential strain (17%). With exercise at HA, the increase in SV was limited (12 vs. 22 ml at SL), and LV apical rotation failed to augment. For the first time, we have demonstrated that EDV does not increase upon exercise at high altitude despite enhanced in vivo diastolic relaxation. The increase in LV mechanics at rest may represent a mechanism by which SV is defended in the presence of a reduced EDV. However, likely because of the higher LV mechanics at rest, no further increase was observed up to 50% peak power. Consequently, although hypoxia does not suppress systolic function per se, the capacity to increase SV through greater deformation during submaximal exercise at HA is restricted.

Generalized Heterodyne Configurations for Photo-induced Force Microscopy

2019 ◽  
Author(s):  
Le Wang ◽  
Devon Jakob ◽  
Haomin Wang ◽  
Alexis Apostolos ◽  
Marcos M. Pires ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Repetition Rate ◽  
Modulation Frequency ◽  
High Harmonic ◽  
Chemical Imaging ◽  
Heterodyne Detection ◽  
Force Microscopy ◽  
Wide Range ◽  
The Difference ◽  
Afm Cantilever

<div>Infrared chemical microscopy through mechanical probing of light-matter interactions by atomic force microscopy (AFM) bypasses the diffraction limit. One increasingly popular technique is photo-induced force microscopy (PiFM), which utilizes the mechanical heterodyne signal detection between cantilever mechanical resonant oscillations and the photo induced force from light-matter interaction. So far, photo induced force microscopy has been operated in only one heterodyne configuration. In this article, we generalize heterodyne configurations of photoinduced force microscopy by introducing two new schemes: harmonic heterodyne detection and sequential heterodyne detection. In harmonic heterodyne detection, the laser repetition rate matches integer fractions of the difference between the two mechanical resonant modes of the AFM cantilever. The high harmonic of the beating from the photothermal expansion mixes with the AFM cantilever oscillation to provide PiFM signal. In sequential heterodyne detection, the combination of the repetition rate of laser pulses and polarization modulation frequency matches the difference between two AFM mechanical modes, leading to detectable PiFM signals. These two generalized heterodyne configurations for photo induced force microscopy deliver new avenues for chemical imaging and broadband spectroscopy at ~10 nm spatial resolution. They are suitable for a wide range of heterogeneous materials across various disciplines: from structured polymer film, polaritonic boron nitride materials, to isolated bacterial peptidoglycan cell walls. The generalized heterodyne configurations introduce flexibility for the implementation of PiFM and related tapping mode AFM-IR, and provide possibilities for additional modulation channel in PiFM for targeted signal extraction with nanoscale spatial resolution.</div>

Beat-to-Beat Analysis of Left Ventricular Pressure-Volume Relation and Stroke Volume by Conductance Catheter and Aortic Modelflow in Cardiomyoplasty Patients

Circulation ◽  
1995 ◽  
Vol 91 (7) ◽  
pp. 2010-2017 ◽  
Author(s):  
J.J. Schreuder ◽  
F.H. van der Veen ◽  
E.T. van der Velde ◽  
F. Delahaye ◽  
O. Alfieri ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Conductance Catheter ◽  
Volume Relation

scholarly journals Cerebral embolism due to left atrial myxoma in a patient presenting with chest pain and ST-segment elevation: a case report

2020 ◽  
Author(s):  
António Fontes ◽  
Nuno Dias-Ferreira ◽  
Anabela Tavares ◽  
Fátima Neves
Keyword(s):  
Myocardial Infarction ◽  
Chest Pain ◽  
Magnetic Resonance ◽  
Left Atrial ◽  
Left Ventricular ◽  
Atrial Myxoma ◽  
Left Atrial Myxoma ◽  
St Segment ◽  
Wide Range ◽  
St Elevation

Abstract Background Myocarditis is an uncommon, potentially life-threatening disease that presents with a wide range of symptoms. In acute myocarditis, chest pain (CP) may mimic typical angina and also be associated with electrocardiographic changes, including an elevation of the ST-segment. A large percentage (20–56%) of myxomas are found incidentally. Case summary A 62-year-old female presenting with sudden onset CP and infero-lateral ST-elevation in the electrocardiogram. The diagnosis of ST-elevation myocardial infarction was presumed and administered tenecteplase. The patient was immediately transported to a percutaneous coronary intervention centre. She complained of intermittent diplopia during transport and referred constitutional symptoms for the past 2 weeks. Coronary angiography showed normal arteries. The echocardiogram revealed moderate to severe left ventricular systolic dysfunction due to large areas of akinesia sparing most of the basal segments, and a mobile mass inside the left atrium attached to the septum. The cardiac magnetic resonance (CMR) suggested the diagnosis of myocarditis with concomitant left atrial myxoma. The patient underwent resection of the myxoma. Neurological evaluation was performed due to mild vertigo while walking and diplopia in extreme eye movements. The head magnetic resonance imaging identified multiple infracentimetric lesions throughout the cerebral parenchyma compatible with an embolization process caused by fragments of the tumour. Discussion Myocarditis can have various presentations may mimic acute myocardial infarction and CMR is critical to establish the diagnosis. Myxoma with embolic complications requires emergent surgery. To the best of our knowledge, this is the first case reported in the applicable literature of a myxoma diagnosed during a myocarditis episode.

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