M-mode Scanning Research Articles

A novel 4D volumetric M-mode ultrasound scanning technique for evaluation of intravascular volume and hemodynamic parameters

IntroductionWe use a novel 4-dimensional (4D) volumetric M-mode (VMM) ultrasound (US) technique to assess intravascular volume by monitoring the inferior vena cava (IVC). The VMM method expands the spatial coverage of standard M-mode scanning (depth vs time) by including lateral image direction and adds transducer tilt to cover the region surrounding the IVC. Current ultrasound methods for volume assessment suffer from intra- and inter-operator variability. The VMM technique aims to address these limitations, aiding in early detection of hypovolemia/hemorrhage and guiding resuscitation. Methods/technical approachThe 4D VMM technique was used on animals that underwent a swine hemorrhagic shock protocol with fluid resuscitation. 2D ultrasound images obtained were formatted in a 3D volume to capture changes over time in vessel size with respiration and volume status. Planes were then extracted from the 3D volume at multiple lateral locations to find and track the IVC. The vessel walls were manually traced on vertical planes (depth vs. time) to determine mean IVC diameter and IVC collapsibility at each measurement time point in the shock/resuscitation protocol. Planes at constant depth (lateral vs. time) were selected to extract respiratory and cardiac cycle data. ResultsMean IVC diameter in the baseline phase was significantly greater than in the hemorrhage phase (p = 0.020). There was no significant different in mean IVC diameter between baseline and resuscitation (p = 0.064) or hemorrhage and resuscitation phases (p = 0.531). There was no statistically significant difference in mean collapsibility or ΔIVC diameter between protocol phases. The 4D VMM technique effectively measured heart and respiratory rates, consistent with monitored vitals. Conclusion4D VMM identified IVC changes corresponding to blood loss and resuscitation during hemorrhagic shock as well as heart/respiratory rates. This innovative approach holds promise in reducing operator variability and providing actionable information during treatment of shock.

Evaluation of Deep Learning Model Architectures for Point-of-Care Ultrasound Diagnostics.

Point-of-care ultrasound imaging is a critical tool for patient triage during trauma for diagnosing injuries and prioritizing limited medical evacuation resources. Specifically, an eFAST exam evaluates if there are free fluids in the chest or abdomen but this is only possible if ultrasound scans can be accurately interpreted, a challenge in the pre-hospital setting. In this effort, we evaluated the use of artificial intelligent eFAST image interpretation models. Widely used deep learning model architectures were evaluated as well as Bayesian models optimized for six different diagnostic models: pneumothorax (i) B- or (ii) M-mode, hemothorax (iii) B- or (iv) M-mode, (v) pelvic or bladder abdominal hemorrhage and (vi) right upper quadrant abdominal hemorrhage. Models were trained using images captured in 27 swine. Using a leave-one-subject-out training approach, the MobileNetV2 and DarkNet53 models surpassed 85% accuracy for each M-mode scan site. The different B-mode models performed worse with accuracies between 68% and 74% except for the pelvic hemorrhage model, which only reached 62% accuracy for all model architectures. These results highlight which eFAST scan sites can be easily automated with image interpretation models, while other scan sites, such as the bladder hemorrhage model, will require more robust model development or data augmentation to improve performance. With these additional improvements, the skill threshold for ultrasound-based triage can be reduced, thus expanding its utility in the pre-hospital setting.

Age-related impacts of wave transmission at the aorta-carotid bifurcation on local and global measures of arterial stiffness

Wave reflections in the periphery have been key in the understanding of aging-related changes in global arterial stiffness, as measured by carotid-femoral pulse-wave velocity (cfPWV). However, recent investigations have demonstrated benefits of using local measures of aortic arch PWV (aaPWV) in addition to considering cfPWV. The contribution of proximal wave reflections at the aorta-carotid bifurcation to aaPWV, as well as to the increasing discordance between aaPWV and cfPWV previously observed with aging, remain poorly understood. The purpose of the present investigation was to examine the impact of transmission of pressure and flow at the aorta-carotid bifurcation on aaPWV and cfPWV in healthy younger and older individuals. We hypothesized that aging-related stiffening of the carotid artery would enhance pressure transmission at the aorta-carotid bifurcation and redirect flow transmission towards a greater relative flow in the distal aortic arch, increasing cfPWV but having minimal impact on aaPWV. We recruited 15 participants, stratified into young adults (YA; n = 8, 4 women; age 20 ± 2.7 years) and older adults (OA; n = 7, 4 women; age 53 ± 2.2 years). Both aaPWV and cfPWV were assessed with ultrasound (Logiq S8, GE Healthcare) via the conventional foot-to-foot velocity waveform method. Carotid artery PWV (caPWV) was calculated using the Bramwell-Hill equation using M-mode scans and carotid pressure waveforms. Carotid, proximal, and distal aortic impedances were derived using estimated blood density, PWV values, and vessel cross-sectional areas. These impedance values allowed for calculation of the pressure and flow transmission coefficients describing the aorta-carotid bifurcation. Sex and BMI were not significantly different between groups (p > 0.05). YA had significantly lower cfPWV (5.2 ± 0.6 vs. 6.8 ± 0.8 m/s, p < 0.05) and caPWV (10.6 ± 0.9 vs. 16.9 ± 1.2 m/s, p < 0.05); however, aaPWV was similar between groups (p > 0.05). This resulted in a reduced pressure transmission coefficient in YA (0.91 ± 0.07 vs. 0.99 ± 0.05, p < 0.05) as well as a greater transmission of flow into the carotid artery relative to the distal aortic arch, represented as the carotid flow transmission coefficient over the distal aortic flow transmission coefficient (0.70 ± 0.20 vs. 0.41 ± 0.1, p <0.05). Linear regression indicated a significant association between caPWV and cfPWV in the entire group, even after adjustment for age, sex and BMI (β = 0.597, p = 0.01) whereas caPWV was not associated with aaPWV in univariate or multivariate analyses. Consistent with our hypothesis, present analyses suggest a role for pressure and flow transmission at the aorta-carotid bifurcation in the dissociation between local stiffness of the proximal aorta (aaPWV) and global arterial stiffness (cfPWV). This highlights the systemic nature of cfPWV, and suggests a need for specificity in the measure of arterial stiffness used and the target outcome of a given study. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

M-mode scan line in ultrasound: A useful guide to identify the midline in central neuraxial block.

M-mode scan line in ultrasound: A useful guide to identify the midline in central neuraxial block.

M-mode Ultrasound Scan as a Potential Alternative Technique for Monitoring Uterine Contractions in Obese Patients.

We investigate motion mode (M-mode) ultrasound scan as a potential non-invasive uterine monitoring technique and compare its contraction characteristics with external tocodynamometry (TOCO). This prospective diagnostic accuracy study included 39 term pregnant woman in active spontaneous labor. M-mode and TOCO were simultaneously performed and uterine contraction characteristics and consistency were compared quantitatively and visually. The results identified a 71.5% ± 35.3% uterine wall thickening during uterine contractions on M-mode. Uterine monitoring with M-mode had a consistency rate of 88.7% ± 6.9% with conventional TOCO method. During 20-min monitoring, the number of detected contractions was significantly higher (p < 0.001) in M-mode (8.2 ± 1.2) than TOCO (7.4 ± 1.5). As for the mean value of the duration of a contraction (seconds), it was significantly shorter (p < 0.001) in M-mode (38.5 ± 3.5) than TOCO (49.2 ± 4.1). For M-mode, the number of detected contractions had a negative but insignificant correlation with the body mass index (BMI) (r = - 0.25 [- 0.52, 0.07], p = 0.127) and the subcutaneous tissue thickness (STT) (r = - 0.21 [- 0.49, 0.11], p = 0.200). As for TOCO, the contractions had a negative and significant correlation with BMI (r = - 0.41 [- 0.64, - 0.11], p = 0.009) and negative and insignificant correlation with STT (r = - 0.26 [- 0.54, 0.06], p = 0.104). The evidence suggests that contraction detection with M-mode is a promising non-invasive technique for uterine monitoring. The preliminary analysis finds that contraction detection is not affected by BMI or STT. With future sensitivity studies, and improvements in image-processing and software technologies, the proposed technique promises to be a viable alternative to existing techniques, especially for obese patients.

Progression of left ventricular diastolic function in the neonate and early childhood from transmitral color M-mode filling analysis

We implemented sophisticated color M-mode analysis to assess age-dependent progression of left ventricular (LV) diastolic function. Normal infants were prospectively enrolled for serial echocardiograms at 1 week, 1 month, 6 months, 1 year, and 2 years. From color M-mode scans, propagation velocity (VP), strength of filling (VS), and intraventricular pressure difference (IVPD) in 3 segments along apex-to-mitral valve scan line were measured. Age-wise comparisons of diastolic filling from 121 echocardiograms in 31 infants showed VP (cm/s), VS (cm2/s), and E-wave IVPD (mmHg) at 1 week to be 66.2 ± 11.9, 75.3 ± 19.9, and 1.5 ± 0.4, respectively, while VP, VS, and E-wave IVPD at 1 month were 80.3 ± 14.4, 101.2 ± 28.3, and 2.42 ± 1.1, respectively. There were significant differences in VP and segmental IVPD between first week and first month (p < 0.005) and IVPD between the age groups (p < 0.001). Comprehensive analysis of transmitral color M-mode data is feasible in infants, enabling calculation of pressure drop between the LV base and apex and strength of propagation from two distinct slopes. Profound changes very early followed by relatively constant filling mechanics in later infancy indicate significant LV maturation occurring during the first month of life. We implemented sophisticated analytic methods for color M-mode echocardiography in infants to assess age- and dimension-dependent changes in left ventricular diastolic function. Comprehensive characterization of transmitral color M-mode flow was feasible, enabling calculation of pressure drop between left ventricular base and apex and strength of propagation. Left ventricular diastolic filling function has predictable maturational progression, with significant differences in the intraventricular pressure between infants from birth to 2 years. This study forms the basis for future studies to examine alteration of early diastolic filling in congenital heart disease.

Capillary red blood cell velocimetry by phase-resolved optical coherence tomography.

We present a phase-resolved optical coherence tomography (OCT) method to extend Doppler OCT for the accurate measurement of the red blood cell (RBC) velocity in cerebral capillaries. OCT data were acquired with an M-mode scanning strategy (repeated A-scans) to account for the single-file passage of RBCs in a capillary, which were then high-pass filtered to remove the stationary component of the signal to ensure an accurate measurement of phase shift of flowing RBCs. The angular frequency of the signal from flowing RBCs was then quantified from the dynamic component of the signal and used to calculate the axial speed of flowing RBCs in capillaries. We validated our measurement by RBC passage velocimetry using the signal magnitude of the same OCT time series data.

Detection of local tissue alteration during retinal laser photocoagulation of ex vivo porcine eyes using phase-resolved optical coherence tomography.

Retinal laser photocoagulation is used to treat several ophthalmic diseases. However, it is associated with damage to surrounding healthy tissue. Local tissue alteration during coagulation laser illumination was measured using phase-resolved optical coherence tomography (OCT) M-mode scan as a change in the local optical path length (LOPL). A metric that represents global net tissue alteration was defined using the LOPL change. The visibility of a laser lesion was assessed by three-dimensional OCT volume measurement. Multiple logistic regression analysis was performed to investigate the association between the introduced metric and the laser lesion visibility. The metric was found to be a statistically significant predictor of the laser lesion visibility independent to laser condition. The proposed method based on an LOPL change is thus promising for retinal photocoagulation monitoring.

Tricuspid Annular Plane Systolic Excursion: Comparing Transthoracic to Transesophageal Echocardiography

Tricuspid annular plane systolic excursion (TAPSE) represents movement of the lateral annulus of the tricuspid valve toward the apex and denotes right ventricular contractility in the long axis. In transesophageal echocardiography with the probe in the mid-esophagus, TAPSE occurs at a significant angle to the M-mode scan line. The authors describe a novel method to assess TAPSE in 2 dimensions (2D) and compare this with an established method. Prospective cohort study. Tertiary cardiac unit. Forty-three patients scheduled for outpatient transesophageal echocardiography. None. TAPSE was assessed from the transthoracic apical window using M-mode (M-TAPSE) and the mid-esophageal 4-chamber view (2D-TAPSE). To assess 2D-TAPSE, the authors placed an annotation arrow at the junction of the tricuspid annulus and right ventricular free wall during diastole, and a second arrow at this junction at end-systole; 2D-TAPSE represented the distance between the arrows. The mean M-TAPSE was 20.5 (5.9) mm and 2D-TAPSE was 20.5 (5.8) mm. The mean angle between the direction of the lateral tricuspid annular motion and the M-mode scan line from the transthoracic apical window was 19.4 (7.6) degrees and from the mid-esophageal 4-chamber view 62.6 (15.7) degrees (p<0.001). There was a close correlation between M-TAPSE and 2D-TAPSE; r2 = 0.93. Ninety-five percent of 2D-TAPSE were -3.2mm to+3.1mm of M-TAPSE (95% confidence interval -4.0 mm to+4.0 mm). The positive predictive value of 2D-TAPSE<17 mm to predict M-TAPSE<17 was 83%. The negative predictive value of 2D-TAPSE≥17 mm to predict M-TAPSE≥17 was 93%. The intra- and inter-observer variability for 2D-TAPSE was 6.7% and 9.7%, respectively. Transesophageal 2D-TAPSE appeared to be a reliable and simple method to assess right ventricular function, and demonstrated a close correlation with transthoracic M-TAPSE.

Photothermal optical coherence tomography based on the localized surface plasmon resonance of Au nanoring.

The conventional optical coherence tomography (OCT) images based on enhanced scattering and the photothermal (PT) images based on enhanced absorption of the localized surface plasmon (LSP) resonance of Au nanorings (NRIs) in a bio-tissue sample are demonstrated with the scans of an OCT system (1310-nm system), in which the spectral range covers the LSP resonance peak wavelength, and another OCT system (1060-nm system), in which the spectral range is away from the LSP resonance peak wavelength. A PT image is formed by evaluating the modulation frequency (400 Hz) response of an excitation laser with its wavelength (1308 nm) close to the LSP resonance peak at 1305 nm of the Au NRI solution. With the scan of the 1310-nm OCT system, the Au NRI distribution in the bio-tissue sample can be observed in both conventional OCT and PT images. However, with the scan of the 1060-nm OCT system, the Au NRI distribution can be clearly observed only in the PT image. The diffusion process of Au NRIs in the bio-tissue sample can be traced with the scan of either OCT system. Based on phantom experiments, it is shown that the PT image can help in resolving the ambiguity of a conventional OCT image between the enhanced scattering of Au NRIs and the strong scattering of a tissue structure in the 1310-nm OCT scanning. Also, under the condition of weak intrinsic sample scattering, particularly in the scan of the 1060-nm system, the PT signal can be lower than a saturating level, which is determined by the excitation power. By increasing OCT system signal-to-noise ratio or M-mode scan time, the PT signal level can be enhanced.

Separate assessment of gluteus medius and minimus: B-mode or M-mode ultrasound?

The hip abductors gluteus medius (Gmed) and minimus (Gmin) differ slightly in function and how they are affected by hip joint pathology. A separate assessment of Gmed and Gmin is feasible by ultrasound (US) imaging. B-mode and M-mode US can be used to measure muscle thickness. Two B- and two M-mode scans of Gmed and Gmin thickness were taken in relaxation on 16 asymptomatic volunteers, repeated within 4 days on 11 subjects. Three types of intra-rater reliability of muscle thickness measurements were examined: (1) within-session reliability comparing two scans from the same session, (2) between-days reliability comparing thickness from two scanning occasion within 4 days and (3) reliability of taking thickness measurements by re-measuring the same US scans after 1 week. Thickness measurements on B- and M-mode images provided ICC3,1 >0.96 for within-session reliability. ICC3,k >0.89 for between-days reliability and ICC3,1 >0.85 for re-reading the same scans were estimated. Minimal detectable changes >1.0 mm within-session, >2.4 mm between-days and >1.7 mm for re-reading scans indicated that small thickness changes are not detectable. The investigation suggests a slight advantage for fascia recognition in B-mode and the advantage of visual control of muscle relaxation in M-mode.

Interventricular septum motion abnormalities: unexpected echocardiographic changes of Brugada syndrome

There remains controversy about whether Brugada syndrome (BS) has structural heart changes. We occasionally noted that a patient with BS had a quite unusual regional wall motion abnormality at the basal segment of the interventricular septum (IVS) during echocardiographic examination. The unexpected finding promoted us to reexamine our patients with BS by echocardiographic interrogation in the present study. Patients with BS (n = 11), patients with complete right bundle branch block (RBBB) (n = 11), and control subjects (n = 11) were enrolled in this study. Two-dimensional echocardiography (2DE) was performed to obtain parasternal left ventricular long axis view on which M-mode scanning line was adjusted to be perpendicular to the basal segment of IVS for delineation of the segmental motion curve, with a simultaneously electrocardiographic tracing. 2DE revealed a rapid swing motion shifting toward the right ventricle of the IVS basal segment at early systole in 73% (8/11) patients with BS, which was further confirmed on the M-mode curve evidenced by an early systolic notch toward the right ventricle. The position of the notch corresponded to C-point on the mitral motion curve, lasting for (53 +/- 5) ms. There were no similar changes both in patients with RBBB and in the control subjects. IVS basal motion abnormalities at early-systolic phase may be the novel finding of BS.

Detection of magnetic nanoparticles in tissue using magneto-motive ultrasound

The purpose of this study was to demonstrate the magneto-motive ultrasonic detection ofsuperparamagnetic iron oxide (SPIO) nanoparticles as a marker of macrophage recruitmentin tissue. The capability of ultrasound to detect SPIO nanoparticles (core diameter∼20 nm) taken up by murine liver macrophages was investigated. Eight mice were sacrificed twodays after the intravenous administration of four SPIO doses (1.5, 1.0, 0.5, and 0.1 mmolFe/kg body weight). In the iron-laden livers, ultrasound Doppler measurements showed afrequency shift in response to an applied time-varying magnetic field. M-mode scan andcolour power Doppler images of the iron-laden livers also demonstrated nanoparticlemovement under focused magnetic field excitation. In the livers of two saline injectedcontrol mice, no movement was observed using any ultrasound imaging modes. The resultsof our experiments indicate that ultrasound imaging of magneto-motive excitation is acandidate imaging modality to identify tissue-based macrophages containing SPIOnanoparticles.

Ultrasonographic patterns of fetal breathing movements in normal pregnancy

Objective: To assess through pregnancy fetal breathing movements (FBMs) patterns detected by M-mode and Doppler velocimetry technology. Methods: In this cross-sectional study FBMs were investigated in 1882 uncomplicated pregnancies over a 4-year period. Abdominal and thoracic wall movements of fetuses between 14 and 40 weeks of gestation were studied by M-Mode scan, and color Doppler velocimetry with spectral imaging analysis was used to investigate the presence of FBMs associated with nasal fluid flow velocity waveforms (NFFVWs). Results: Abdominal movements were observed in 19% of cases when gestation was less than 20 weeks and in 61% of cases when it was between 21 and 25 weeks; chest movements were significant after 21 weeks; and NFFVWs were detected at 22 weeks and increased progressively to 93% of cases at term. Conclusions: Fetal breathing movements are a complex phenomenon with a composite, progressive pattern of development during gestation.

Simplified Biophysical Profile: An Antepartum Fetal Screening Test

A total of 330 high-risk pregnant women with gestational ages of 32–42 weeks were followed until delivery using the biophysical profile (BPP) and a screening test consisting of the amniotic fluid index together with fetal acoustic stimulation under ultrasound M-mode scanning. The test was compared with the BPP and nonstress test (NST) for predicting abnormal outcome. The sensitivities of the BPP, NST and the proposed test were 100, 98.4 and 100%, respectively, the negative predictive values were 100, 99.4 and 100%, while the false-positive rates were 21.3, 39.3 and 67%. Our simplified biophysical testing method is suggested to be a good negative preliminary screening test, while positive results require further fetal testing methods. This test reduced the need for BPP in many high-risk patients and had the advantages of simplicity, low cost and less time consumption.

Doppler tissue imaging: myocardial wall motion velocities in normal subjects

With a scanner modified for Doppler tissue imaging, mean myocardial velocities (MMV) across the myocardium were measured. The aim of this study was to determine the normal range of the maximum MMV in six standardized phases of the cardiac cycle. The MMV was defined as the average value of the myocardial velocity measured along each M-mode scan line throughout the thickness of the myocardium. The maximum MMV was defined as the maximum value of the MMV during the particular cardiac phase. Simultaneous gray-scale and Doppler tissue imaging M-mode images were taken of the interventricular septum and the left ventricular posterior wall from the parasternal long-axis and short-axis views in 15 normal volunteers (aged 21 to 47 years; mean 32 +/- 6 years). Each cardiac cycle was divided into six phases: atrial contraction, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, rapid ventricular filling, and diastasis. Isovolumetric contraction, isovolumetric relaxation, and diastasis were subdivided into two parts a and b because of changes in the direction of the myocardial movement. For each volunteer, the mean and standard deviation of the maximum MMV were measured for each cardiac phase averaged from 12 cardiac cycles from both long-axis and short-axis views. Finally, the mean and standard deviation were taken for each cardiac phase from 180 cardiac cycles from 15 volunteers. We have found that specific cardiac phases show significant differences in the maximum MMV between the adjoining cardiac phases and significant differences also occur between the maximum MMV measured in the interventricular septum and the left ventricular posterior wall during the same cardiac phases. These normal values provide a standard against which future Doppler tissue imaging M-mode studies of abnormal left ventricular function might be compared.

901-117 Mitral Valve Prolapse: Is it Associated with Acute Ischemic Neurologic Events?

A high frequency of association has previously been reported between acute ischemic neurological events and mitral valve prolapse (MVP), especially in young patients (&lt;45 years old), primarily based on M-mode scans. Criteria for diagnosing MVP, however, have subsequently changed based on 3D analysis of valve shape and clinical correlations, greatly decreasing its prevalence. It is therefore necessary to reconsider associations previously described using nonspecific M-mode and two-dimensional (2D) echo criteria. We retrospectively reviewed all echo studies performed from 1985 to 1994 in patients &lt;45 years old referred by their physician because of stroke or transient ischemic attack looking for source of embolus. Patients with known or potential sources such as prosthetic heart valves, intracardiac masses, dilated or aneurysmal LV. or congenital heart defects were excluded. MVP was evaluated using 2D echo criteria now widely accepted (in long-axis views, excluding nonspecific anterior leaflet displacement in the 4-chamber view; these criteria correlate with valve dysfunction and valve-related complications). Of the 244 patients evaluated, only 3 (1.2%) had MVP (anterior, posterior and bileaflet with thin valves and normal LA size). All 3 patients also had a patent foramen ovale with shunt. Discussion: Earlier studies using less specific M-mode criteria found MVP in up to 40% of young patients with stroke or TIA, but also in 7–21% of otherwise healthy individuals. In contrast, the very low prevalence of MVP in the present group of patients, despite referral for echocardiography (potential bias towards the diagnosis), suggests the association is much smaller, possibly at the level of random association. The linkage of MVP and acute ischemic neurological events in the young, therefore, could not be demonstrated by more recent validated and accepted 2D echo criteria in an echocardiographic referral population.

Myocardial velocity gradients detected by Doppler imaging

Using a scanner whose colour Doppler mode has been adapted to display tissue motion (instead of blood flow), velocity gradients have been detected across the myocardium. A velocity gradient is a gradual spatial change in the value of velocity estimates. Velocity gradients have potential for assessing regional myocardial contractility. 28 M-mode scans were performed on nine normal volunteers at different locations in the left-ventricle posterior wall. In each case simultaneous Doppler M-mode and pulse-echo M-mode images were obtained. Doppler velocity gradient (DVG) was calculated from Doppler M-mode images and rate of change of wall thickness (RCWT) was calculated from pulse-echo M-mode images. In all Doppler M-mode images statistically significant velocity gradients were observed. In all but one scan, cyclically consistent peaks in DVG occur relative to the electrocardiogram waveform. 99% of systolic and 89% of early diastolic peaks in RCWT have a corresponding peak in DVG. Velocity gradients are consistent with wall thickness changes, suggesting that they have potential for assessment of myocardial contractility.

Comparative value of transthoracic and transesophageal echocardiography in the assessment of congenital abnormalities of the atrioventricular junction

Information obtained from transthoracic and transesophageal echocardiography (two-dimensional echocardiography with spectral Doppler and color How imaging) was compared in 17 patients with major congenital ibnormalities of the atrioventricular (AV) junction (10 discordant AV connections, 1 criss-cross connection, 5 absent right connections and 1 absent left connection). The findings by either technique were correlated with findings at cardiac catheterization (12 patients) and at surgery (5 patients).In two of six patients with an absent AV connection as defined by transthoracic echocardiography, transesophageal imaging demonstrated an imperforate AV valve. In 11 of 11 patients with a discordant or criss-cross connection, assessment of AV valve and ventricular morphology (by defining the chordal attachments of both AV valves) was possible with transesophageal echocardiography (3 of 11 patients by transthoracic echocardiography); chordal straddling was detected in 1 patient and excluded in 3 others with an associated inlet ventricular septal defect. Anomalous pulmonary venous connection (one patient), atrial septal defect (three patients) and subpulmonary stenosis (five patients) were better assessed by transesophageal imaging, and atrial appendage morphology could be demonstrated in all.The transesophageal technique was less useful in demonstrating the anterior subaortic infundibulum or aortopulmonary shunt (two patients). Although systemic ventricular function could be assessed by either method with use of short-axis M-mode scans, transasophagerel pulsed Doppler interrogation of AV valve and pulmonary venous flow patterns provided clues to diastolic dysfunction of the systemic ventricle.

Splenic artery and superior mesenteric artery blood flow: nonsurgical Doppler US measurement in healthy subjects and patients with chronic liver disease.

The accuracy of the duplex Doppler ultrasound system in the measurement of blood flow in the splenic artery and the superior mesenteric artery was evaluated in seven anesthetized dogs by comparing blood flow recordings obtained simultaneously with the electromagnetic flowmeter, with those obtained with the combination of B-mode and M-mode scanning. Various flow rates were produced by the infusion of dopamine. Splenic artery blood flow and superior mesenteric artery blood flow measured with the duplex system exhibited significant correlations with corresponding values obtained with electromagnetic flow measurements (r = .93 and r = .93, respectively). Changes in splanchnic circulation with the progression of chronic liver disease in humans were then investigated with the use of the duplex system. Splenic artery blood flow and superior mesenteric artery blood flow were significantly increased in patients with cirrhosis compared with patients with chronic hepatitis and healthy subjects. These results indicate that a hyperdynamic circulatory state may develop in the splanchnic circulation of the intestine and spleen in cirrhotic patients.