Microembolic signals under increased ambient pressure.
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Animals↗
Biomedical subjects
H Bot
Publications and source records attributed to H Bot.
Pathogenesis of mitral regurgitation in acute myocardial infarction: importance of changes in left ventricular shape and regional function.
The pathogenesis of mitral regurgitation (MR) was determined by quantitative echocardiography in 188 patients with acute myocardial infarction (AMI) within 48 hours after admission. MR was classified, by using color Doppler, as significant (grades 3 to 4) or trivial (grades 0 to 2). Left ventricular (LV) function (global and regional), volume, and shape, as well as mitral valvular features, were measured and analyzed by stepwise logistic regression. Significant MR occurred in 25 (13%) patients. Univariately, recurrent infarction (p < 0.01), LV dilation (p < 0.001) and sphericity (p < 0.001), inferoposterolateral asynergy (p < 0.001), mitral annular dilatation (p < 0.005), and mitral leaflet restriction (p < 0.05) were associated with significant MR. In regression analysis, only recurrent infarction (odds ratio 5.08), LV sphericity index (odds ratio 1.12), and inferoposterolateral asynergy (odds ratio 6.07) were independently associated with significant MR, whereas none of the mitral valvular features examined had an independent association. In conclusion, changes in LV shape and regional function and not mitral valvular changes are prime determinants of significant MR after AMI.
Aged↗
Left ventricular thrombus in acute myocardial infarction.
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Angiocardiography↗
Usefulness of mitral regurgitation in protecting against left ventricular thrombus after acute myocardial infarction.
In conclusion, we documented an increased incidence of LV thrombus in patients with MR after AMI.
Blood Flow Velocity↗
Doppler left ventricular flow pattern versus conventional predictors of left ventricular thrombus after acute myocardial infarction.
OBJECTIVES: The value of Doppler-derived left ventricular spatial flow patterns in predicting left ventricular thrombus formation after myocardial infarction was compared with that of conventional clinical and echocardiographic variables. BACKGROUND: Assessment of left ventricular thrombosis risk after myocardial infarction is important because of potential embolic sequelae that are reduced by oral anticoagulant agents. METHODS: Clinical, two-dimensional and Doppler echocardiographic data were prospectively obtained in 104 patients with acute myocardial infarction within 48 h of admission. Ventricular flow was assessed by Doppler echocardiography and considered normal when brisk ventricular inflow with simultaneous onset at the mitral valve and apical levels was present, together with alternating directions of apical flow throughout the cardiac cycle. In addition to normal flow, two abnormal flow patterns were recognized: apical rotating flow and vortex ring formation. Oral anticoagulant agents were prescribed only to patients with abnormal flow at admission. The incidence of left ventricular thrombosis was assessed by echocardiography during 9 months of follow-up. RESULTS: Abnormal flow pattern had a positive predictive value of 63% and a negative predictive value of 99%. On stepwise logistic regression analysis, only abnormal flow pattern had an independent relation to left ventricular thrombus (odds ratio 92). CONCLUSIONS: Left ventricular flow pattern derived by Doppler echocardiography soon after admission is superior to conventional clinical and two-dimensional echocardiographic assessment in estimating the risk of left ventricular thrombosis after myocardial infarction.
Blood Flow Velocity↗
Left atrial appendage blood flow determined by transesophageal echocardiography in healthy subjects.
Transesophageal echocardiography was performed in 46 healthy subjects to define characteristics of normal left atrial appendage blood flow. Three different flow wave patterns were observed that were heart rate dependent (p < 0.01). A quadriphasic pattern, consisting of 2 diastolic forward (emptying) flow waves each followed by a backward (filling) flow wave, was present in 36 subjects (78%). Triphasic appendage flow was observed in 6 subjects (13%) and biphasic flow in 4 (9%). Mean heart rates among subjects with quadri-, tri- and biphasic flows were 75 +/- 11, 95 +/- 6 and 112 +/- 7 beats/min, respectively. Analysis of pulsed Doppler recordings of subjects with quadriphasic or triphasic appendage flow patterns showed that the onset of transmitral early diastolic peak flow wave was followed at 17 +/- 15 ms by the onset of pulmonary venous diastolic flow and at 43 +/- 17 ms by the onset of the first diastolic forward flow in the appendage. This sequence was constant and independent of heart rate (p < 0.01), suggesting a causal relation between left ventricular relaxation and the first diastolic forward flow wave in the appendage. The second diastolic forward flow followed the P wave on the electrocardiogram at 79 +/- 23 ms. Thus, left atrial appendage blood flow pattern in normal subjects is heart rate dependent, and ventricular relaxation appears to initiate early diastolic emptying of the appendage.
Adult↗
Spectral analysis of flow velocity in the contralateral artery during coronary angioplasty: a new method for assessing collateral flow.
OBJECTIVES: The present study was designed to evaluate a new method for assessing coronary collateral flow and resistance in conscious humans. BACKGROUND: Earlier pathomorphologic and invasive studies have indicated that collateral vessels are important for salvage of myocardium at risk in acute myocardial infarction. Only a few clinical studies have attempted to express the development of the collateral vascular bed in terms of flow or resistance. METHODS: Angiography and flow velocity measurements of the contralateral coronary artery were performed in 38 patients undergoing coronary angioplasty for one-vessel disease. Coronary flow velocity was assessed by zero-crossing frequency analysis in 37 patients and, additionally, by fast Fourier transform spectral analysis in 23. Collateral flow was determined by the decrease of flow velocity after balloon deflation. Mean aortic pressure and coronary wedge pressure were assessed for calculation of collateral vascular resistance. RESULTS: Angiography of the contralateral artery during balloon inflation revealed the presence of collateral vessels in 26 patients (recruitable collateral vessels in 19). Fast Fourier transform spectral analysis demonstrated a significant transient increase of flow velocity during brief coronary occlusion in 15 patients with collateral vessels compared with 8 patients without collateral vessels (4.8 +/- 1.3% vs. 23.4 +/- 17.2%, p < 0.001). A transient increase in flow velocity (> 10%) was less evident by zero-crossing frequency analysis than by fast Fourier transform spectral analysis (sensitivity 8% vs. 87%). The relative resistance of the collateral vascular bed was significantly reduced when collateral vessels were present during coronary occlusion (4.4 +/- 3.8 vs. 16.9 +/- 4.6, p < 0.001). Furthermore, electrocardiographic signs of ischemia were less present in those 15 patients with collateral vessels (p < 0.05). CONCLUSIONS: The beneficial effect of collateral vessels during brief coronary occlusion is exerted by a significant increase of flow in the contralateral artery in combination with a reduced resistance in the collateral vascular bed. The method presented is capable of expressing the development of the collateral vascular bed in terms of flow and resistance.
Adult↗
T cell-mediated induction of airway hyperresponsiveness and altered lung functions in mice are independent of increased vascular permeability and mononuclear cell infiltration.
Previously it was demonstrated that during delayed-type hypersensitivity reactions (DTH) to picryl chloride (PCl) in murine lungs, as a model for cellular IgE-independent immunity, tracheal hyperreactivity and increased pulmonary resistance are induced. In the present study it is demonstrated that after pretreatment with 5HT-2 antagonists, such as ketanserin and methysergide, DTH lung reactions to PCl in mice are suppressed. The increase in vascular permeability, detectable at 2 h after intranasal hapten challenge and probably necessary for the development of a classic DTH reaction, as was demonstrated in skin DTH models, as well as the classic late inflammatory component of lung DTH, is inhibited. However, in vitro tracheal hyperreactivity to the cholinergic receptor agonist carbachol and increased pulmonary resistance in vivo, both induced during the development of these inflammatory DTH lung reactions, are not affected by 5HT-2 receptor antagonist pretreatment. These results indicate that the actual presence of increased vascular permeability and mononuclear infiltrates is not a prerequisite for the development of changed lung functions and tracheal hyperresponsiveness. Thus in mice, serotonin-independent mechanisms that appear during T cell-dependent lung immune reactions induce airway hyperresponsiveness and increased pulmonary resistance.
Animals↗
A role for T cells in the induction of airway hyperreactivity.
In this study we investigated a possible relationship of delayed type hypersensitivity (DTH), as a model for cellular IgE-independent immunity, with the induction of airway hyperreactivity. In PC1 (picryl chloride) sensitized BALB/c mice DTH-like lung infiltrates were found that were maximal 48 hr after intranasal hapten challenge. During the elicitation of this DTH-like reaction tracheal hyperreactivity to the cholinergic agonist carbachol could be detected from 2 hr after challenge with the homologous hapten and that was maximal after 48 hr.
Animals↗
Early Indium-111 antimyosin scintigraphy for assessment of regional wall motion asynergy on discharge after myocardial infarction.
To assess the relation between early Indium-111 monoclonal antimyosin antibody scintigraphy and degree of regional asynergy on discharge, 38 patients with a first acute myocardial infarct were studied (18 anterior, 20 inferoposterior infarctions). In 21 patients thrombolytic therapy was administered. On the first day of myocardial infarction, 80 MBq Indium-111 Antimyosin was injected. Planar images, anterior, lateral and left anterior oblique, were made 24 hours later. Localized myocardial uptake was present in 37/38 patients, and was evaluated for Count Density Index (count density of infarct zone/left lung count density) in the left anterior oblique images, which displayed the infarct zone well. Regional asynergy on discharge was evaluated by cross-sectional echocardiography and defined mild (hypokinesia) or severe (akinesia or dyskinesia). Count density index was significantly lower in 15 patients with mild asynergy, compared with 22 patients with severe asynergy (1.61 +/- 0.25 vs. 2.42 +/- 0.40, p less than 0.001). This difference was present in both patient groups treated with or without thrombolysis. We conclude that early count density index, reflecting the amount of local necrosis, is highly correlated to the ultimate degree of wall motion impairment.
Antibodies, Monoclonal↗
Determinants of the occurrence of vortex rings in the left ventricle during diastole.
This study employs classical inviscid fluid dynamics theory to investigate whether LV diastolic inflow volume and the size of the LV play a role in vortex ring formation. Fluid injection across an orifice into a large container results in the generation of a vortex ring having a constant size and speed. Relations between the vortex size and speed and the injection were obtained by applying conservation laws regarding kinetic energy, impulse and vorticity; the initial state was computed using a bolus injection model, and the final state by using the Kelvin vortex model. An important parameter in the equations is the relative injection length, i.e., the ratio of the length of the injected bolus and the radius of the orifice (L/R). Its estimated highest value in man, L/R = 15, produces a rather thick vortex ring (relative thickness 0.77). Comparable results following from the Hill vortex model convinced us that the Kelvin vortex model can be applied in the whole range of injection lengths in the human left ventricle. In an in vitro model it is shown experimentally that vortex rings can be generated for L/R in the range from 2 to 16. The measured traveling speed of the vortex ring is in fair agreement with the theory, as well as the ring radius for large injections. A vortex ring located in a narrow channel cannot reach its proper traveling speed. The method of images is used to estimate the speed reduction of vortex rings within a cylinder. It turns out that propagation of vortex rings is possible when the ratio of orifice to cylinder radius is less than about 0.5.(ABSTRACT TRUNCATED AT 250 WORDS)
Biomechanical Phenomena↗
Prediction of apical thrombus formation in acute myocardial infarction based on left ventricular spatial flow pattern.
The predictive value of the left ventricular spatial flow pattern for thrombus formation was determined in 62 patients with acute myocardial infarction. A normal flow pattern by pulsed Doppler echocardiography was characterized by 1) simultaneous onset of blood motion at the mitral valve and apical level, and 2) a discontinuous Doppler signal along the lateral wall and interventricular septum. The flow pattern was assessed by these criteria, within 24 h after the onset of complaints and after 6 and 12 weeks. In 46 of the 62 patients, a normal flow pattern was found at the first examination; none of these 46 patients developed a thrombus during the study period. An abnormal flow pattern was seen at the first examination in 16 patients; this pattern normalized during follow-up in 6 patients, none of whom developed a thrombus. In the other 10 patients the abnormal flow pattern persisted, and 7 of these developed a thrombus. These findings suggest that a normal left ventricular flow pattern in the setting of acute myocardial infarction is not associated with subsequent thrombus formation. This observation may be of importance if anticoagulation is considered.
Aged↗
Predictive value of indium-111 antimyosin uptake for improvement of left ventricular wall motion after thrombolysis in acute myocardial infarction.
In 21 patients treated with thrombolysis for acute myocardial infarction (AMI), the degree of myocardial uptake of indium-111 monoclonal antimyosin antibodies injected within 24 hours after onset of AMI was compared with the degree and extent of regional asynergy on admission and discharge, as assessed by 2-dimensional echocardiography. On the first day of AMI, 80 MBq of indium-111 antimyosin was injected and planar images were made 24 hours later. Indium-111 antimyosin uptake was evaluated for count density index (count density of infarct zone/left lung count density) in the left anterior oblique projection, in which the infarction zone was well displayed in all patients. Using 2-dimensional echocardiography, the left ventricle was divided into 13 segments and evaluated for regional asynergy, which was considered severe (akinesia or dyskinesia) or mild (hypokinesia). The extent of regional asynergy was measured by the number of asynergic segments. All 21 patients had severe regional asynergy on admission. Nine of 21 showed only mild regional asynergy on discharge and 12 of 21 had persistent severe regional asynergy in at least 1 segment. The count density index was significantly lower in patients with mild regional asynergy on discharge compared with patients with severe regional asynergy (1.63 +/- 0.27 vs 2.50 +/- 0.42, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Phasic flow in the left ventricular inflow tract: the importance of Doppler sample volume position.
Variability of Doppler transmitral flow was studied in 42 normal patients (aged 19-68 years). Starting at the mitral annulus level (ANL) in an apical four-chamber view, the sample volume was moved downstream at 1-cm intervals. At all positions, peak early (E) and later atrial mediated (A) diastolic velocity were measured, and the distance from the transducer to the level with the highest E wave (HEL) and highest A wave (HAL) determined. The A/E ratio and time velocity integral (TVI) at ANL, HAL, and HEL were also calculated. Peak E velocity at HEL was 33% higher than at ANL (p less than 0.01) and peak A velocity was 15% higher at HAL than at ANL (p less than 0.01). The A/E ratio was minimal at HEL and maximal at ANL (0.68 +/- 0.28 vs 0.85 +/- 0.32, p less than 0.01), whereas TVI was highest at HEL and lowest at ANL. Thus, inflow parameters vary along the inflow axis. This is of importance for cardiac output measurement. The A/E ratio was more dependent on age than on sample volume position.
Adult↗
[Determination of blood flow velocity in the heart using Doppler echocardiography].
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Blood Flow Velocity↗
Limits of reproducibility of blood flow measurements by Doppler echocardiography.
This study evaluates the variability of a quantitative Doppler echocardiographic method for blood flow calculation at the mitral and tricuspid orifice. Four subjects underwent 2-dimensional Doppler echocardiography during normal respiration and nonrespiration. Doppler recordings were integrated to determine mean temporal velocity (MTV) for each cardiac cycle separately. MTV during inspiration and expiration were compared, as were MTVs of 20 consecutive cycles during nonrespiration. Diameters of mitral and tricuspid orifice and interception angles were measured in 10 consecutive cycles at 4 predetermined moments. All results were averaged to a mean subject situation. MTVs were significantly (p less than 0.001) higher during expiration than during inspiration (12.4 and 11.0 cm-2) for the mitral orifice and lower (9.2 and 11.0 cm-2) for the tricuspid orifice. MTV at both orifices showed a significantly smaller variability (7.7% and 9.0%) during nonrespiration than during respiration (14.5% and 13.2%). Diameters of mitral orifice and tricuspid orifice were significantly (p less than 0.001) larger during diastole than during systole whereas standard error of the mean for both was 5.0%. Interception angles measured at mitral orifice are all close to 0 degrees and show minimal variability, while at the tricuspid orifice the angle varied from 15 degrees in diastole to 25.5 degrees in systole, constituting a significant difference in cosine (0.96 to 0.90).
Adult↗
Diastolic flow characteristics of severely impaired left ventricles: a pulsed Doppler ultrasound study.
Left ventricular inflow was studied with pulsed Doppler echocardiography in 12 normals and 12 patients with a dilated left ventricle as a result of ischemic heart disease. To study the influence of left ventricular relaxation on both the transmitral and apical diastolic flow patterns, we applied range ambiguity. This provides simultaneous display of Doppler shifts obtained at different depths. The diastolic Doppler shift curves at the mitral valve and apical level in normals had the same time of onset, whereas there was an apparent time delay in the patients with heart disease (range 160-360 ms). This might be caused by absence of a normal apical wall motion in these patients.
Adult↗
Signal processing in 2 dimensional Doppler echocardiography.
Blood flow recordings made by 2 dimensional Doppler echocardiography can sometimes be understood more easily than conventional Doppler recordings, because of the anatomical 2 dimensional presentation. In contrast, signal processing has become more complicated and requires more explanation. In 2 dimensional Doppler echocardiography the analog ultrasonic signal received by the transducer is converted into an audible signal, which next is digitized and analyzed for its mean frequency and variance. Data collection and processing require application of multigating and high speed frequency analysis, generally based upon autocorrelation. Some artifacts may be perceived, such as color reversal due to aliasing, deceptively colored tissue surfaces due to beam motion, and wall motion ghost signals due to multiple reflections. Color flow imaging is appropriate for a rapid scan of the heart cavities to detect and roughly evaluate flow abnormalities. Quantification is still accomplished by switching to conventional Doppler mode.
Echocardiography↗