Ultrasonic diagnostic instruments.

The underlying physical principles and current limitations of diagnostic ultrasonic instruments are reviewed. Recently developed ultrasonic imaging devices using pulsed-reflected ultrasound are discussed in detail. These instruments transmit short trains of 1.5- to 10-megahertz sound. Echoes reflected from tissue are converted to electrical signals, which are presented on a display device to outline the contour of tissues and organs within the body. The physical resolution of the system is dependent on several design factors in addition to the transmitted sound frequencies. A resolution volume of approximately 1.5 by 3 by 4 millimeters is achieved optimally with commercially available systems operating at 2.25 megahertz. The various instrument designs are described in the context of clinical usage. Because the sound is diffracted, refracted, and reflected, tghe imaging considerations are different from those of x-ray imaging. Diagnostic devices based on the Doppler principle are distinguished from pulsed-reflected ultrasonic instruments.

Two-dimensional echocardiographic assessment of bioprosthetic valve dysfunction and infective endocarditis.

Two-dimensional echocardiography of Hancock porcine heterograft valves was evaluated by correlation with clinical, hemodynamic, angiographic and pathologic findings in 80 patients. Ninety-five aortic and mitral bioprostheses were categorized by the type of valvular abnormality: group I, dysfunction due to primary tissue failure (41 valves); group II, dysfunction due to paravalvular leakage without infection (5 valves); group III, infective endocarditis with or without hemodynamic dysfunction (28 valves); and group IV, control cases without dysfunction or infection (21 valves). Increased size of a bioprosthetic leaflet image (minimal dimensions 3 x 5 mm) was observed in 46% (19 of 41) of cases with primary tissue failure and in 62% (10 of 16) of cases with leaflet vegetations due to endocarditis. Prolapse of leaflet echoes to below the level of the bioprosthetic sewing ring occurred in 76% (28 of 37) of cases with torn leaflets and also in 46% (6 of 13) of valves with vegetations on intact leaflets. Antegrade extension of leaflet echoes to beyond the level of the stents, observed in 4 of 16 cases with leaflet vegetations, was the only echocardiographic sign distinguishing leaflet infection from leaflet degeneration. Aortic bioprostheses with ring dehiscence affecting 40 to 90% of the anular circumference showed motion discordant with the motion of the adjacent aortic root and native anulus. Although echocardiographic abnormalities are frequently observed with bioprosthetic leaflet degeneration or infection, the echocardiographic appearance often does not distinguish between these two major complications and is best interpreted concurrently with other clinical and laboratory assessment.

Lessons from in vitro models of small, irregular, multiple and tunnel-like stenoses relevant to clinical stenoses of valves and small vessels.

This review examines data on the accuracy of the simplified Bernoulli equation for quantitation of pressure drops across small, irregular, multiple and tunnel-like stenoses. This information is drawn from in vitro models of such cardiovascular stenoses and explores the limits of this simplification as they affect accuracy in special situations. Within the physiologic range, discrete small and irregular stenoses present no problems for the measurement of pressure drops using the simplified Bernoulli equation. Multiple side by side orifices of different dimension also give reasonable data using this approach. Tunnel-like stenoses of very small diameter and finite length produce underestimation of the true pressure drop through the stenosis when the simplified Bernouli equation is used. This underestimation is primarily due to neglect of the energy consumed by viscous friction in this situation. These considerations are especially pertinent to the problem of measuring pressure gradients across coronary vessels to assess their clinical significance as well as the adequacy of angioplasty and other intravascular interventional techniques. Because this area needs further exploration, some discussion of in vitro models as such as included.

Patterns and timing of Doppler-detected intracavitary and aortic flow in hypertrophic cardiomyopathy.

This study describes the velocity characteristics of left ventricular and aortic outflow in 25 patients with hypertrophic "obstructive" cardiomyopathy. Systematic pulsed and continuous wave Doppler analysis combined with phonocardiography and M-mode echocardiography was used to establish the pattern and timing of outflow in the basal and provoked states. This analysis suggests that 1) the high velocity left ventricular outflow jet can be reliably discriminated from both aortic flow and the jet of mitral regurgitation using Doppler ultrasound; 2) the Doppler velocity contour responds in a characteristic fashion to provocative influences including extrasystole and Valsalva maneuver; 3) the onset of mitral regurgitation occurs well before detectable systolic anterior motion of the mitral valve; 4) left ventricular flow velocities are elevated at the onset of systolic anterior motion of the mitral valve, suggesting a significant contribution of the Venturi effect in displacing the leaflets and chordae; 5) the high velocities of the outflow jets are largely dissipated by the time flow reaches the aortic valve; and 6) late systolic flow in the ascending aorta is nonuniform, with formation of distinct eddies that may contribute to "preclosure" of the aortic valve.

Detection of endocarditis-associated perivalvular abscesses by two-dimensional echocardiography.

The development of a perivalvular abscess as a complication of infective endocarditis adds appreciably to the expected morbidity and mortality of patients, but such abscesses are seldom recognized by available noninvasive techniques. Therefore, two-dimensional echocardiographic findings in 22 patients with perivalvular abscess found at surgery or necropsy were compared with those in 24 patients without abscess in a retrospective but blinded study. Forty-six valves were examined (31 aortic and 15 mitral, 35 prosthetic and 11 native); 4.0 +/- 2.4 days (range 0 to 7) elapsed between echocardiography and surgery or necropsy. Patients with perivalvular abscess had a somewhat higher incidence of serious complications (emergency repeat valve replacement or death) than did patients with endocarditis alone (63 versus 35%, respectively, p less than 0.05). No single echocardiographic finding was frequently seen with a perivalvular abscess. A "typical" echo-free abscess was noted in only one patient; however, the presence of one or more of the following had a positive predictive value of 86% and a negative predictive value of 87% for the presence of perivalvular abscess: prosthetic valve rocking; sinus of Valsalva aneurysm, anterior aortic root thickness of 10 mm or greater, posterior aortic root thickness of 10 mm or greater or perivalvular density in a septum of 14 mm or greater. These predictive values, of course, apply only to patients with infective endocarditis going to surgery, and may assist the surgeon in knowing whether or not to expect an abscess.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic recognition of paraseptal structures.

Improved echocardiographic equipment provides detailed images of the heart and shows anatomic paraseptal structures previously not well defined. Echocardiograms were analyzed from 33 patients who later underwent cardiac transplantation, and the paraseptal structures noted were correlated with the pathologic specimens. Patterns associated with right ventricular chordae tendineae, the moderator band and the posterior papillary muscle are illustrated. Hypertrophic and fibrotic right ventricular trabeculae and left ventricular paraseptal bands are noted. These structures can be specifically sought and identified using the current generation of echocardiographs, thereby avoiding potential problems of septal definition and measurement.

Superior vena cava and hepatic vein Doppler echocardiography in healthy adults.

Pulsed wave Doppler ultrasound recordings of blood flow velocity in the superior vena cava were made in 40 healthy adults (aged 22 to 69 years) during both normal respiration and 10 second episodes of apnea. The forward flow velocity pattern was biphasic, with systolic flow velocity greater than diastolic flow velocity. During apnea, peak flow velocities ranged from 32 to 69 cm/s (mean 45.7 +/- 8.4) during systole and from 6 to 45 cm/s (mean 27.2 +/- 8.3) in early diastole. Systolic flow velocity integrals also exceeded diastolic values. With atrial systole (A wave), forward flow velocities were reduced or flow was reversed. Thirty-nine of 40 subjects had A wave flow reversal during apnea, and in these the ratio of reverse to total forward flow velocity integrals ranged from 1 to 16% (mean 6 +/- 4%). Compared with values during apnea, there were higher mean values with inspiration and lower values with expiration for velocities and flow velocity integrals. Hepatic vein tracings, when adequate (12 of 40 subjects), showed forward flow characteristics similar to those from the superior vena cava, but with more frequent and larger A wave and ventricular end-systole (atrial V wave) flow reversals. Superior vena cava flow velocity variables were calculated in subgroups to assess the effects of age, respiratory pattern and increased venous return. This study defines normal Doppler ultrasound superior vena cava and hepatic vein flow velocities and their variation with respiration in healthy adults. These results can be used for comparison with patterns found in disease states.

Cardiac tamponade and pericardial effusion: respiratory variation in transvalvular flow velocities studied by Doppler echocardiography.

Cardiac tamponade has been associated with an abnormally increased respiratory variation in transvalvular blood flow velocities. To determine whether this finding is consistently present in cardiac tamponade, seven patients were studied prospectively with Doppler echocardiography before and after pericardiocentesis and the results were compared with those found in 20 normal adults and 14 asymptomatic patients with pericardial effusion who did not have definite clinical evidence of tamponade. Doppler ultrasound evaluation included measurement of mitral, tricuspid, aortic, pulmonary and central venous flow velocities, as well as left ventricular ejection and isovolumic relaxation times during inspiration, expiration and apnea. In the patients with severe cardiac tamponade, respiratory variation in transvalvular flow velocities and left ventricular ejection and isovolumic relaxation times were markedly increased compared with values in normal subjects and those obtained after pericardiocentesis. In the 14 asymptomatic patients with pericardial effusion but without overt tamponade, 7 showed respiratory variation in flow velocity similar to that of normal subjects. The other seven patients demonstrated increased respiratory change compared with normal, but less than that in the patients with tamponade. Clinical and hemodynamic data in this latter group suggest that these patients may represent an intermediate stage of pericardial effusion with an element of hemodynamic compromise.

Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure.

The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. Eleven patients had third degree AV block and a ventricular-inhibited (VVI) pacemaker, two patients had second degree AV block, seven patients had first degree AV block, one patient had blocked premature atrial complexes and one patient had atrial flutter with 4:1 AV block. Diastolic mitral regurgitation was detected in 20 patients, and diastolic tricuspid regurgitation in 21. A mid-diastolic murmur was detected in all patients except in the three youngest. The murmur occurred before diastolic regurgitation and coincided with peak forward flow through the AV valve after atrial contraction. M-mode mitral valve echocardiograms obtained in nine patients demonstrated near closure of some portions of the mitral valve after atrial contraction. Effective closure of the valve, however, did not occur unless ventricular systole supervened. In conclusion, diastolic mitral and tricuspid regurgitation are almost universally present in patients with AV block and are associated with a diastolic murmur. The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.

Demonstration of restrictive ventricular physiology by Doppler echocardiography.

In patients with restriction of cardiac filling of various origins, cardiac catheterization has been traditionally used as part of the diagnostic evaluation to verify the presence of restrictive/constrictive hemodynamics. In an attempt to determine whether this "restrictive" physiology could be demonstrated noninvasively, 14 patients who had a history, physical examination, two-dimensional echocardiogram and catheterization data compatible with a restrictive myocardial process were studied with pulsed wave Doppler ultrasound. Forty normal subjects served as a control group. The Doppler ultrasound evaluation included measurement of peak mitral and tricuspid flow velocities and flow velocity integrals, mitral and tricuspid deceleration times and central venous flow patterns during apnea and inspiration. The flow velocity recordings across the mitral and tricuspid valves in patients manifesting restriction were markedly different from those in normal subjects, showing shortened deceleration times across both valves, which indicated both an abrupt premature cessation of ventricular filling and the presence of a diastolic dip-plateau contour in ventricular pressure recordings. In addition, abnormal central venous flow velocity reversals with inspiration and diastolic mitral and tricuspid regurgitation were frequently observed, also suggesting the reduced myocardial compliance characteristic of a restrictive myocardial process.

Evaluation of clinical competence in cardiovascular disease.

The American Board of Internal Medicine has called on directors of cardiology training programs to establish systems to evaluate, document and substantiate those components of overall clinical competence considered essential for certification in the subspecialty. Many of these can be assessed only by repeated direct observations. In particular, proficiency is now required in advanced cardiac life support including cardioversion, electrocardiography (including ambulatory electrocardiographic monitoring) and exercise testing, echocardiography, insertion of arterial lines and right heart catheterization (including insertion of temporary pacemakers). The goal of this expanded evaluation program is to ensure that the public and the profession can identify, through certification, physicians with demonstrated excellence in cardiovascular disease.

Doppler echocardiographic measurement of aortic valve area in aortic stenosis: a noninvasive application of the Gorlin formula.

Thirty adult patients with aortic stenosis had Doppler echocardiography within 1 day of cardiac catheterization. Noninvasive measurement of the mean transaortic pressure gradient was calculated by applying the simplified Bernoulli equation to the continuous wave Doppler transaortic velocity recording. Stroke volume was measured noninvasively by multiplying the systolic velocity integral of flow in the left ventricular outflow tract (obtained by pulsed Doppler ultrasonography) by the cross-sectional area of the left ventricular outflow tract (measured by two-dimensional echocardiography). Non-invasive measurement of aortic valve area was calculated by two methods. In method 1, the Gorlin equation was applied using Doppler-derived mean pressure gradient, cardiac output and systolic ejection period. Method 2 used the continuity equation. These noninvasive measurements were compared with invasive measurements using linear regression analysis, and mean pressure gradients correlated well (r = 0.92). Aortic valve area by either noninvasive method also correlated well with cardiac catheterization values (method 1, r = 0.87; method 2, r = 0.88). The sensitivity of Doppler detection of critical aortic stenosis was 0.86, with a specificity of 0.88 and a positive predictive value of 0.86. Cardiac output measured nonsimultaneously showed poor correlation (r = 0.51). Doppler echocardiography can distinguish critical from noncritical aortic stenosis with a high degree of accuracy. Measurement of aortic valve area aids interpretation of Doppler-derived mean pressure gradient data when the gradients are in an intermediate range (30 to 50 mm Hg).

Filling patterns in left ventricular hypertrophy: a combined acoustic quantification and Doppler study.

OBJECTIVES: The purpose of this study was to evaluate the potential of acoustic quantification compared with Doppler echocardiography for assessment of left ventricular diastolic dysfunction. BACKGROUND: Diastolic dysfunction usually accompanies left ventricular hypertrophy. Although Doppler echocardiography is widely used, it has known limitations in the diagnosis of diastolic abnormalities. The ventricular area-change waveform obtained with acoustic quantification technology may provide an alternative to assess diastolic dysfunction. METHODS: Potential acoustic quantification variables (peak rate of area change and mean slope of area change rate during rapid filling, amount of relative area change during rapid filling and atrial contraction) were obtained and compared with widely used Doppler indexes of ventricular filling (isovolumetric relaxation time, pressure half-time, peak early diastolic velocity/peak late diastolic velocity ratio, rapid filling, atrial contribution to filling) in 16 healthy volunteers and 30 patients with left ventricular hypertrophy. RESULTS: Criteria for abnormal relaxation were present in 68% of patients by acoustic quantification and in 64% of patients by Doppler echocardiography. However, abnormal relaxation was identified in 80% of patients by one or both methods. Acoustic quantification indicated abnormal relaxation in the presence of completely normalized Doppler patterns and in patients with mitral regurgitation or abnormal rhythm with unreliable Doppler patterns. CONCLUSIONS: Acoustic quantification potentially presents a new way to assess diastolic dysfunction. This technique may be regarded as complementary to Doppler echocardiography. The combined use of the methods may improve the diagnosis of left ventricular relaxation abnormalities.

Effects of nitroprusside on transmitral flow velocity patterns in extreme heart failure: a combined hemodynamic and Doppler echocardiographic study of varying loading conditions.

To explore the mechanisms of change of left ventricular diastolic filling associated with preload and afterload reduction, the influence of nitroprusside on the transmitral flow velocity pattern, pulmonary capillary wedge pressure and left ventricular pressure interaction was studied in 11 patients with end-stage heart failure. Pulsed Doppler echocardiographic recordings of mitral inflow were obtained with simultaneous high fidelity left ventricular and phase-corrected pulmonary capillary wedge pressure recordings before and during levels of nitroprusside infusion. With nitroprusside, left ventricular systolic and end-diastolic pressures decreased by 14% and 41% (p less than 0.05, p less than 0.05), respectively, and cardiac output increased by 67% (p less than 0.05). The pulmonary capillary wedge-left ventricular crossover pressure decreased by 41% (p less than 0.05), but the time constant of isovolumetric left ventricular pressure decrease T was insignificantly changed. Isovolumetric relaxation time and acceleration and deceleration times of the early diastolic filling wave were significantly prolonged with nitroprusside infusion (p less than 0.05, p less than 0.05 and p less than 0.05, respectively). Peak early diastolic filling velocity was maintained (65 +/- 11 to 62 +/- 13 cm/s, p = NS) in spite of the decreased absolute crossover pressure. Changes in peak early diastolic filling velocity correlated weakly with changes in the crossover pressure (r = 0.48, p less than 0.05) and correlated better with the crossover to left ventricular minimal pressure difference (r = 0.78, p less than 0.05). Peak early diastolic filling velocity appears to be most affected by the early diastolic pulmonary capillary wedge to left ventricular pressure difference rather than the absolute pulmonary capillary wedge pressure. The lack of peak flow velocity change during nitroprusside infusion could be explained by either the associated decrease in left ventricular minimal pressure or downward shift of left ventricular diastolic pressure by the same amount as the decrease in pulmonary capillary wedge pressure. This may reflect a reduction of external constraint to ventricular distensibility produced by a reduction in filling volume in patients with a markedly dilated ventricle. Thus, a prolonged early diastolic filling period and preserved peak early diastolic filling velocity in spite of decreased left ventricular filling pressure and constant relaxation rate are associated with the beneficial effects of nitroprusside on left ventricular function in patients with severe congestive heart failure.

Relation of transmitral flow velocity patterns to left ventricular diastolic function: new insights from a combined hemodynamic and Doppler echocardiographic study.

In an effort to determine what clinically useful information regarding left ventricular diastolic function can be inferred noninvasively with pulsed wave Doppler echocardiography, mitral flow velocity patterns and measured variables were correlated with hemodynamic findings in 70 patients: 30 with coronary artery disease, 20 with idiopathic congestive cardiomyopathy, 14 with a restrictive myocardial process and 6 without significant cardiac disease. The effect of sudden changes in hemodynamics on the mitral flow velocity pattern was also investigated in a subgroup of patients who had simultaneous recording of mitral flow velocity and left ventricular pressure before and after left ventriculography. Mitral flow velocity recordings from 30 healthy adults served as a reference group. This analysis suggests that 1) the majority of patients with these cardiac disorders demonstrate abnormal mitral flow velocity patterns or variables; 2) markedly different flow velocity patterns can be seen in patients with impaired left ventricular relaxation; 3) the different mitral patterns appear to relate more to myocardial function and hemodynamic status than to the type of disease process present; 4) certain mitral patterns suggest different filling pressures and rates of early diastolic left ventricular filling; 5) an increase in left atrial pressure can "normalize" an abnormal mitral flow velocity pattern and "mask" a left ventricular relaxation abnormality; and 6) the different patterns appear to represent a dynamic continuum with the potential to change from one to another as a result of disease progression, medical therapy or sudden changes in hemodynamics. It is concluded that, despite the indirect method of estimation and certain limitations, mitral flow velocity recordings have clinical potential in assessing left ventricular diastolic function that merits further investigation.

Standardized intracardiac measurements of two-dimensional echocardiography.

Thirty-five healthy adults were studied by two-dimensional echocardiography to attempt to standardize a simple method for measurement of intracardiac dimensions. Both ventricles and the atria and aorta were measured in five different views: parasternal long-axis, parasternal short-axis at the level of the aortic valve, the chordae tendineae and the papillary muscles and an apical four chamber view. The minor axis of each chamber was measured in all five views; the major axis in the apical four chamber view also was measured. All measurements are presented as a range of values (mean and 2 standard deviations about the mean); the mean value is given as well as the absolute range of values measured. Normalization according to body surface area is also presented. Data from these multiple views allow assessment of asymmetry of cardiac chambers in normal subjects. The mean minor axis dimension at end-diastole of the right ventricle in the parasternal long-axis view (1.9 to 3.8 cm) was 13.6% smaller than in the four chamber view (2.2 to 4.4 cm), whereas the minor axis dimension of the left ventricle in the parasternal long-axis view (3.5 to 6.0 cm) was only 1.1% larger than in the four chamber view (3.3 to 6.0 cm). Therefore, the right ventricular minor axis dimensions are not interchangeable. Reproducibility in 10 subjects for all dimensions showed a maximal variability of 4.8%. These values permit a standardized and expeditious method for measuring intracardiac dimensions by two-dimensional echocardiography.

Effect of variation in PQ interval on patterns of atrioventricular valve motion and flow in patients with normal ventricular function.

M-mode echocardiography and Doppler ultrasonography were used to study patterns of atrioventricular (AV) valve motion and flow in five patients with complete heart block, normal ventricular function and an implanted dual chamber pacemaker with programmable PQ intervals. Changes in AV valve motion and flow patterns resulting from steady state changes in PQ interval over the range studied (75 to 250 ms) were similar in all patients. Events reflecting AV valve opening and rapid ventricular filling bore a constant temporal relation to the Q wave and were unaffected by changes in PQ interval. Events reflecting atrial contraction occurred progressively earlier in diastole with lengthening of the PQ interval, until superimposition of atrial contraction on rapid ventricular filling at a PQ interval of 250 ms. The duration of mid-diastolic slow ventricular filling and overall diastole, defined with respect to an open valve, decreased with lengthening of the PQ interval. The onset of AV valve closure (A point) bore a constant temporal relation to the P wave, indicating that atrial systole initiated valve closure. However, completion of AV valve closure occurred progressively earlier with respect to the P wave as the PQ interval was decreased. This suggests an increasing contribution of ventricular systole to completion of AV valve closure with decreasing PQ interval. End-diastolic and end-systolic ventricular and atrial dimensions were independent of the PQ interval.

Reproducibility of left ventricular volumes by two-dimensional echocardiography.

Reproducibility may be as important as absolute accuracy in assessing the utility of an echocardiographic method of left ventricular volume estimation for epidemiologic or physiologic studies. The magnitude of differences between measurements in the same subjects from day to day must be defined before any quantitative technique can be used reliably to document "real" changes in heart volume over time. Two-dimensional echocardiograms were performed serveral days apart in 30 subjects, including 20 normal subjects and 10 patients with stable coronary heart disease. Analyses of light-pen tracings provided measurements of end-diastolic volume, endsystolic volume and derived ejection fraction on both days, and differences in individual subjects between days were quantitated. Beat to beat, interobserver and intraobserver variability also were assessed. Although group values changed little from day to day, individual volume changes were substantial in some cases. Confidence limits for individual measurements were derived from analyses of intrasubject variability and were as follows: end-diastolic volume +/- 15%, end-systolic volume +/- 25%, ejection fraction +/- 10%. Confidence limits in a larger group of subjects were narrower; in a group of 30 subjects, changes of greater than 2% in end-diastolic volume, 5% in end-systolic volume and 2% in ejection fraction most likely represent real change. Intraobserver variability was minimal, but interobserver and beat to beat variability were of sufficient magnitude to suggest that serial measurements on a given subject be made ideally by a single person and that several cycles be averaged for a given measurement.

Intraventricular flow during isovolumic relaxation: description and characterization by Doppler echocardiography.

This study describes the characteristics of a prominent Doppler flow velocity signal representing intraventricular flow during left ventricular isovolumic relaxation. The flow during the isovolumic relaxation period was demonstrated in 60 subjects, including 7 with a normal heart, 26 with hypertrophic cardiomyopathy, 10 with aortic valve disease, 9 with a transplanted heart and 8 others. All had normal to hyperdynamic left ventricular systolic function with some degree of cavity obliteration as seen in the apical two-dimensional echocardiographic views. In contrast, this isovolumic relaxation period flow could not be demonstrated in the absence of cavity obliteration in any of 20 patients with either normal or diminished left ventricular systolic function. Isovolumic relaxation period flow was best recorded from the apical transducer position and was directed toward the apex in all patients. By pulsed wave, and with two-dimensional Doppler ultrasound, the isovolumic relaxation period flow originated within a narrow area in the medial portion of the left ventricle along the middle or basal segments of the interventricular septum, but was recorded over a larger area toward the apex. The peak isovolumic relaxation period flow velocity was recorded just basal to the area of cavity obliteration, usually at the level of the papillary muscles, and ranged from 0.4 to 2.3 m/s (mean of 1.0 m/s). This isovolumic relaxation period flow started with aortic valve closure and, in 50 of the 60 patients, it lasted throughout isovolumic relaxation until mitral valve opening. In the other 10 patients (all with hypertrophic cardiomyopathy), it lasted for only a part (mean 63%) of this period.(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler echocardiographic determination of the pressure gradient in hypertrophic cardiomyopathy.

The continuous wave Doppler ultrasound signal across the left ventricular outflow tract in hypertrophic cardiomyopathy has a characteristic pattern that is in keeping with the dynamic nature of the pressure gradient in this condition. To determine the accuracy and reliability of the peak Doppler flow velocity signal for measuring the peak pressure gradient in this condition, 340 beats were analyzed from five consecutive patients studied with simultaneous continuous wave Doppler ultrasound and dual catheter pressure recordings across the left ventricular outflow tract. Each patient was studied at steady state and during physiologic and pharmacologic manipulations of the pressure gradient. Peak velocity and calculated peak gradient were determined by two independent observers who did not know the catheter measurements. In addition, 18 beats with well defined flow velocity envelopes were digitized for analysis of the magnitude, timing and contour of the instantaneous Doppler ultrasound and catheter gradients throughout systole. Peak catheter gradient in the 340 beats ranged from 12 to 245 mm Hg. The correlations between the Doppler-derived and catheter peak gradients were close (r = 0.96, SEE = 4 mm Hg for Observer 1 and r = 0.97, SEE = 11 mm Hg for Observer 2). Interobserver variability for measurement of peak flow velocity was small (mean +/- SD 0.16 +/- 0.15 m/s). An interobserver difference greater than 0.3 m/s occurred in 25 of the 340 beats analyzed. By retrospective analysis, this was due to contamination of the outflow tract signal by mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)