Non-invasive cardiac assessment in beta-thalassaemia major.

Iron deposition in the heart occurs in beta-thalassaemia major and contributes to cardiac dysfunction. Eighteen patients with beta-thalassaemia major were assessed clinically and had non-invasive investigations. They were young (15.5 +/- 3.6 years). Two patients had clinical heart failure. Doppler echocardiography demonstrated higher transmitral peak flow velocity in early and late diastole compared with controls (e: p<0.05, a: p<0.01). Transtricuspid peak late diastolic flow velocity was higher in patients (p<0.005). Isovolumic relaxation time was shortened (p<0.001). Pulmonary venous flow velocity was higher in diastole than systole (S: 0.51 +/- 0.11 m/s, D: 0.62 +/- 0.08 m/s). Reversal of pulmonary venous flow during atrial systole was seen in eight patients. These diastolic filling abnormalities did not significantly change with blood transfusion. Left ventricular ejection fraction was normal in patients. Two patients had cardiomegaly on chest X-ray. In beta-thalassaemia with iron overload, there is a restrictive pattern of diastolic dysfunction. This is not altered by recent blood transfusion. Left ventricular function remains relatively intact.

Doppler myocardial imaging in the assessment of normal and ischemic myocardial function--past, present and future.

Myocardial ischemia is associated with impaired regional myocardial function. Echocardiography is a suitable technique for the assessment of regional myocardial function as it is easily applicable and commonly available. However, most of the currently used echo-techniques are based on 2D images or M-mode traces. Therefore, they are limited either to the assessment of myocardial segments that can be insonated at 90 degrees or are based on visually assessed wall motion scoring which is semiquantitative at best. Doppler myocardial imaging (DMI) is a new ultrasound technique which assesses the velocity of myocardial motion. Different parameters can be derived from this velocity information such as velocity time integrals, intramural velocity gradients and strain/strain-rate information. Moreover, DMI provides information of the timing of regional motion related to myocardial contraction and relaxation. These parameters are all assessed quantitatively, therefore, DMI is a promising technique to quantify myocardial function, avoiding the disadvantages of observer-dependant judgement of myocardial contraction.

Changes in systolic and postsystolic wall thickening during acute coronary occlusion and reperfusion in closed-chest pigs: Implications for the assessment of regional myocardial function.

The aim of the study was to characterize the impact of short-lived total coronary occlusions in closed-chest pigs on radial wall thickening within the "at-risk" myocardial segment by using gray-scale M-mode echocardiography. Twelve pigs underwent a series of 20-second total circumflex coronary artery occlusions with an angioplasty balloon. Myocardial thickening/thinning indexes were continuously monitored before ischemia, during ischemia, and on reperfusion by high-resolution M-mode recordings of the posterior wall obtained from parasternal views. The timing of regional events was compared with global systolic time intervals derived from the color Doppler myocardial imaging velocity data. Each occlusion induced a rapid decrease in end-systolic thickening (epsilon(ES)), closely paralleled by an increase in postsystolic thickening in the ischemic segment. After 20 seconds of ischemia, epsilon(ES) decreased by -86% and postsystolic thickening increased by +100%, whereas maximal thickening decreased only by -34% in comparison with preocclusion values. All wall thickening parameters returned to baseline after 15 seconds of reperfusion. During acute total ischemia in a closed-chest animal model, the changes in regional myocardial function were best characterized by the combined analysis of systolic and postsystolic thickening abnormalities and by their respective timings relative to global cardiac events markers.

Doppler myocardial imaging in the assessment of regional myocardial function in longitudinal direction pre- and post-PTCA.

AIMS: Doppler myocardial imaging is potentially a sensitive tool to assess regional myocardial velocities pre- and post-percutaneous transluminal coronary angioplasty (PTCA) as a marker of contractility to evaluate short- to medium-term information on functional myocardial recovery following the release of ischaemia. METHODS: Thirty patients with single vessel disease were studied to assess regional myocardial peak systolic velocity, systolic velocity time integral and mitral valve plane excursion in longitudinal direction one day pre-, one day post- and 3 months post-PTCA. The patients were assigned to group A with coronary stenoses >70% and group B with stenoses < 70%. RESULTS: In group A pre-PTCA the ischaemic segments showed a significantly lower peak systolic velocity and velocity time integral compared with the values one day after PTCA (5.8 +/- 1.4 vs 7.7 +/- 1.4cm.s(-1); 1.06 +/- 0.22 vs 1.23 +/-0.28cm;P< 0.03). In contrast, mitral valve plane excursion in this group remained unchanged after PTCA for both the ischaemic and non-ischaemic left ventricular wall. In group B no changes of these parameters and no differences in mitral valve plane excursion of the ischaemic and the non-ischaemic left ventricular wall could be seen. CONCLUSION: With Doppler myocardial imaging it was possible to quantify a number of indices which changed due to the successful release of ischaemia.

Assessment of regional longitudinal myocardial strain rate derived from doppler myocardial imaging indexes in normal and infarcted myocardium.

Myocardial deformation properties may be characterized by regional strain rates (SRs) calculated from Doppler myocardial velocity data. In 10 control subjects and 12 patients with established transmural infarcts, longitudinal median segmental SR, strain, and myocardial velocity were analyzed and compared with the corresponding wall motion score. All segments in control subjects and normal segments in infarct patients showed no significant difference in either systolic or diastolic SR (systolic: -1.27+/-0.39 s(-1) versus -1.23+/-0.24 s(-1), not significant [NS]; and isovolumic relaxation [IVR]: 1.23+/-0.38 s(-1) versus 1.95+/-0.62 s(-1), NS; respectively) and strain (-0.21+/-0.06 versus -0.19+/-0.06, NS). In infarcted segments, peak systolic SR, systolic strain, and early diastolic SR showed the most pronounced reduction (hypokinetic and akinetic) or even inversion (dyskinetic segments: 0.10+/-0.26 s(-1), 0.00+/-0.03, and -1.78+/-0.67 s(-1), respectively; P<.001). In this study, new myocardial deformation indexes were shown to quantitatively describe the function of normal and chronically infarcted regions.

The noninvasive assessment of left ventricular diastolic function with two-dimensional and Doppler echocardiography.

Left ventricular diastolic filling can be determined reliably by Doppler-derived mitral and pulmonary venous flow velocities. Diastolic filling abnormalities are broadly classified at their extremes to impaired relaxation and restrictive physiology with many patterns in between. An impaired relaxation pattern identifies patients with early stages of heart disease, and appropriate therapy may avert progression and functional disability. Pseudonormalization is a transitional phase between abnormal relaxation and restrictive physiology and signifies increased filling pressure and decreased compliance. In this phase, reducing preload, optimizing afterload, and treating the underlying disease are clinically helpful. A restrictive physiology pattern identifies advanced, usually symptomatic disease with a poor prognosis. Therapeutic intervention is directed toward normalizing loading conditions and improving the restrictive filling pattern, although this may not be feasible in certain heart diseases. Finally, many patients have left ventricular filling patterns that appear indeterminate or mixed. In these cases, clinical information, left atrial and left ventricular size, pulmonary venous flow velocity, and alteration of preload help assess diastolic function and estimate diastolic filling pressures.

Noninvasive computerized assessment of left ventricular performance and systemic hemodynamics by study of aortic root pressure and flow estimates in healthy men, and men with acute and healed myocardial infarction.

Aortic root pressure and flow data can be used to assess left ventricular (LV) performance and properties of the systemic arterial tree. The calibrated subclavian arterial pulse trace was combined with echocardiographic imaging and Doppler velocity recordings to obtain noninvasive estimates of aortic root pressure and flow in 8 healthy subjects (group A), 12 patients with recent myocardial infarction (group B), and 8 with healed myocardial infarction and a dilated left ventricle (group C). The pressure and flow data were transferred to a computer and processed in specially designed software, including a new procedure for estimation of 3-element windkessel model parameters. There were no significant group differences for either aortic root pressure estimates or heart rate. In groups B and C, stroke and cardiac indexes were lower and total peripheral resistance higher than in group A. There were no group differences in the model estimates of total arterial compliance, whereas the characteristic impedance was greater in group C than in A, indicating a less compliant aorta in C. Both LV total and steady power were less in groups B and C than in A, whereas no group difference was found for percent oscillatory power. The reproducibility for recording was good for the aortic root pressure estimates, and lower for the derived parameters (stroke and cardiac indexes, windkessel model parameters and LV power), whereas that for interpretation was generally good. This method provides a unique noninvasive access to important parameters of LV function and the systemic circulation.

Comprehensive Doppler assessment of right ventricular diastolic function in cardiac amyloidosis.

To assess right ventricular diastolic function in cardiac amyloidosis, pulsed wave Doppler ultrasound measurements of right ventricular inflow velocities and superior vena cava and hepatic vein flow velocities with respiratory monitoring were performed in 41 patients with primary systemic amyloidosis and two-dimensional echocardiographic features of cardiac involvement. Right ventricular diastolic function was abnormal in 31 (76%) of these patients, the major abnormality being a short deceleration time (less than 150 ms) in 21 (68%), suggesting restriction. In contrast, 7 (23%) of the 31 patients had a decreased ratio of early (E) and late (A) diastolic peak flow velocities and a prolonged deceleration time (greater than 240 ms), suggesting abnormal relaxation. The patients were classified into two groups on the basis of right ventricular free wall thickness: group 1, less than 7 mm and group 2, greater than or equal to 7 mm. Compared with normal values, group 1 showed an increased peak late flow velocity (44 +/- 19 versus 39 +/- 6 cm/s; p less than 0.01) and a decreased E/A velocity ratio (1.1 +/- 0.4 versus 1.5 +/- 0.3; p less than 0.01). Group 2 showed a markedly shortened deceleration time (151 +/- 37 versus 225 +/- 28 ms; p less than 0.01), characteristic of restriction. In the overall group, superior vena cava peak flow velocity was decreased in systole and increased in diastole and flow reversals during inspiration were increased compared with normal values. Hepatic venous flow velocities were similar to those in the superior vena cava except for larger flow reversals in the hepatic vein. Thus, in cardiac amyloidosis, right ventricular diastolic function is abnormal. There is a spectrum of right ventricular filling abnormalities and the restrictive filling pattern is seen only in the advanced stages of the disease.

Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part II. Clinical studies.

Evaluation of diastolic filling of the heart has been difficult because of its complexity and the numerous interrelated contributing factors. Previous determinations have depended on high-fidelity, invasive measurements of instantaneous pressure, volume, mass, and wall stress, which could not be done on a routine clinical basis. With the advent of Doppler echocardiography, intracardiac blood flow velocities can now be noninvasively assessed. For application of this technique to evaluation of diastolic function in patients with heart disease, it is necessary to understand what the Doppler-derived variables represent. It is also necessary to know how they are affected by changes in loading conditions and changes in myocardial relaxation. In this review, we provide an interpretation of the mitral valve, tricuspid valve, and systemic and pulmonary venous inflow velocities in the normal patient and in various disease states.

Assessment of diastolic function of the heart: background and current applications of Doppler echocardiography. Part I. Physiologic and pathophysiologic features.

In the past, evaluation of the myocardium has been limited to examining systolic function of the heart. Recently, however, investigators have demonstrated that abnormalities of diastolic function of the heart provide important contributions to the signs and symptoms experienced by patients with heart disease. In addition, abnormalities of diastolic function may precede abnormalities of systolic function in the early stages of disease. Diastolic filling of the heart, however, is a complex sequence of interrelated events. In order to understand diastolic function, each of these factors contributing to filling of the heart must be examined. They include relaxation, passive compliance, atrial contraction, erectile effect of the coronary arteries, viscoelastic properties, ventricular interaction, and pericardial restraint--all of which are interrelated. In addition, diastolic factors are affected by changes in loading conditions and contractility, and they demonstrate nonuniformity in time and space. This report provides an overview of these various factors from the clinical perspective, based on studies involving the isolated papillary muscle and the isolated heart as well as basic clinical studies.

Diagnosis and assessment of valve stenosis and regurgitation and coarctation of the aorta with Doppler ultrasound.

With the use of Doppler ultrasound localized increases in blood flow velocities can be recorded and used to diagnose obstructions to blood flow. From the increase in maximal velocities the pressure drop across an obstruction can be calculated, both the peak instantaneous and the mean pressure drop. Regurgitations are diagnosed by recording reversal of blood flow across the valve. Semi-quantitative evaluation of the degree of regurgitation can be made by using both jet width, extension and intensity, as well as increase in forward flow velocity, reversal of flow in great vessels and influence on pressures. In coarctation of the aorta localized increase in velocity in the descending aorta can be shown and the pressure drop can be calculated. In some, more than one level of obstruction can be shown. In neonates the presence of a patent ductus arteriosus may mask the obstruction and a significant pressure drop may become apparent only when narrowing or closure of the duct occurs.

Assessment of aortic blood flow velocities with continuous wave Doppler ultrasound in the neonate and young child.

Aortic flow velocities can be recorded with pulsed or continuous wave Doppler ultrasound. In the absence of obstruction or regurgitation, changes in flow can be assessed and stroke volume obtained. Continuous wave Doppler ultrasound has the advantage that there is no limit to the velocities that can be recorded. In left ventricular outflow obstruction and coarctation, the pressure drop across these can be calculated from increases in maximal velocity using a modification of the Bernoulli equation. Other systolic high velocity jets such as mitral regurgitation or ventricular septal defect may also be recorded with continuous wave Doppler ultrasound from the suprasternal notch, but they can be distinguished from aortic flow velocities by their timing and duration when the flow signals are recorded together with the electrocardiogram and phonocardiogram. In aortic regurgitation, reversal of flow across the aortic valve in diastole can be shown and with high velocity in the regurgitant jet.

Noninvasive assessment of valve lesions with Doppler ultrasound.

Noninvasive assessment of valvular lesions with Doppler echocardiography is based on determination of velocities of blood flow in the region of cardiac valves, adjacent cardiac chambers and in the large vessels. Obstructions lead to an increase in the velocity of flow in the region of the stenosis which can be registered with the Doppler technique. Through application of the Bernoulli equation, from the maximal velocity, the pressure gradient across the stenotic valve can be calculated. Additionally, the severity of the stenosis is reflected in the temporal course of the velocity curve of the jet through the stenosed valve. For this purpose, in mitral stenosis, the pressure half-time is employed and, in aortic stenosis, the peak of the velocity curve during systole is used. The severity of tricuspid and pulmonic stenosis can also be classified with a method analogous to that used in obstruction of the left heart. The diagnosis of valvular incompetence is based on the detection of regurgitant flow. The extent of regurgitant flow into the proximal cardiac chamber enables semiquantitative classification of severity. The intensity of the jet through the incompetent valve is also indicative of the size of the regurgitant volume. Similar to that in obstructive lesions, the temporal course of the velocity curve is also related to the severity. In association with high-grade regurgitant lesions, there is a premature decrease in the velocity curve. Additionally, the severity of aortic regurgitation can be assessed on the basis of the extent of regurgitant flow in the descending aorta or the subclavian arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment and differentiation of left ventricular outflow obstruction with Doppler ultrasound.

Blood flow velocities in the left ventricle and the ascending aorta were recorded noninvasively with Doppler ultrasound. The ultrasound beam was aligned as much as possible to the direction of velocity, using the frequency shift in the audio signal as a guide to obtain velocities as close as possible to those present. From the maximal velocity recorded by continuous-wave Doppler, a peak pressure drop was calculated in 24 patients with aortic valve stenosis and nine with fixed subaortic stenosis. Fourteen patients with aortic stenosis and three with fixed subaortic stenosis were catheterized. In these patients, the correlation between calculated pressure drops and those obtained by pressure recording was good (r = 0.85). The pressure drop can be underestimated by underestimating velocity, but cannot be overestimated. With pulsed Doppler, the level of obstruction can be determined.

Noninvasive diagnosis and assessment of ventricular septal defect by Doppler ultrasound.

The presence of ventricular septal defect can be diagnosed noninvasively by Doppler ultrasound. Care must be taken to distinguish between VSD and infundibular pulmonary stenosis. VSD was easily differentiated from other cardiac lesions. In 55% of the patients a pressure drop across the VDS, comparable to that present, could be calculated from maximal recorded. In the remaining patients velocity and pressure drop were underestimated, probably due to a too large angle between ultrasound beam and velocity. Pulmonary artery systolic pressure was correctly estimated from Pc-To interval and heart rate, and RPEP(RVET) indicated whether normal or raised diastolic pressure was present in most patients.

Non-invasive assessment of aortic stenosis by Doppler ultrasound.

The peak pressure drop across the aortic valve in aortic stenosis has been measured by Doppler ultrasound. Maximum velocity in the Doppler signal from the aortic jet was recorded using a maximum frequency estimator. With an angle close to zero between ultrasound beam and maximal velocity in the jet, peak pressure drop can be calculated from the maximal velocity measured; a larger angle will underestimate maximal velocity and pressure drop. In 57 of 63 patients with aortic stenosis, the aortic jet could be reached by the ultrasound beam and, in 37 of these, peak pressure drop by ultrasound was compared with that obtained at catheterisation. In patients less than 50 years of age the aortic jet was easy to find, the measurement was reproducible, and underestimation of the pressure drop obtained at catheterisation was within 25 per cent in 17 of 18 patients. In patients over 50 years Doppler signals from the aortic jet were more difficult to obtain, and pressure drop was significantly underestimated in one-third, but time of maximum velocity in systole could indicate whether moderate or severe aortic stenosis was present.

Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound.

The mean pressure drop across the mitral valve and atrioventricular pressure half-time were measured noninvasively by Doppler ultrasound in 40 normal subjects, in 17 patients with mitral regurgitation, 32 patients with mitral stenosis and 12 with combined stenosis and regurgitation. In normal subjects pressure half-times were 20--60 msec, in patients with isolated mitral regurgitation 35--80 msec and in patients with mitral stenosis 90--383 msec. There was no significant change in pressure half-time with exercise or on repeat examinations, indicating relative independence of mitral flow. In 25 patients with mitral stenosis and seven with combined stenosis and regurgitation, pressure half-time was related to mitral valve area calculated from catheterization data. Increasing pressure half-times occurred with decreasing mitral valve area, and this relationship was not influenced by additional mitral regurgitation. Noninvasive measurement of pressure half-time together with mean pressure drop was useful for evaluating patients with mitral valve disease.

Noninvasive assessment of pressure drop in mitral stenosis by Doppler ultrasound.

A noninvasive method is described for measuring the pressure drop across the mitral valve in mitral stensois by Doppler ultrasound. A maximum frequency estimator was used to record maximum velocity in the Doppler signal from the mitral jet. Provided the angle between the ultrasound beam and the maximum velocity is close to zero the pressure drop can be calculated directly. Good correlation was found between Doppler measurements and simultaneous pressure recordings during heart catheterisation in 10 patients. No false negative or false positive diagnoses of mitral stenosis were made among 55 patients (35 patients with mitral stenosis and 20 patients with other valve lesions). The measurements were easy to perform in most patients and the method seems well suited both to diagnose and to follow patients with mitral stenosis.