Left atrial relaxation and left ventricular systolic function determine left atrial reservoir function.

BACKGROUND: Determinants of left atrial (LA) reservoir function and its influence on left ventricular (LV) function have not been quantified. METHODS AND RESULTS: In an open-pericardium, paced (70 and 90 bpm) pig model of LV regional ischemia (left anterior descending coronary constriction), with high-fidelity LV, LA, and RV pressure recordings, we obtained the LA area with 2D automated border detection echocardiography, LA pressure-area loops, and Doppler transmitral flow. We calculated LV tau, LA relaxation (a-x pressure difference divided by time, normalized by a pressure), and stiffness (slope between x and v pressure points of v loop). Determinants of total LA reservoir (maximum-minimum area, cm(2)) were identified by multiple regression analysis. Different mean rates of LA area increase identified 2 consecutive (early rapid and late slow) reservoir phases. During ischemia, LV long-axis shortening (LAS, LV base systolic descent) and LA reservoir area change decreased (7.3+/-0.3 [SEM] versus 5.6+/-0.3 cm(2), P<0.001) and LA stiffness increased (1.6+/-0.3 versus 3.1+/-0.3 mm Hg/cm(2), P=0.009). Early reservoir area change depended on LA mean ejection rate (LA area at ECG P wave minus minimum area divided by time; multiple regression coefficient=0.9; P<0.001) and relaxation (coefficient=4.9 cm(2)xms/s; P<0.001). Late reservoir area change depended on LAS (coefficient=8 cm/s; P<0.001). Total reservoir filling depended on LA stiffness (coefficient=-0.31 cm(4)/mm Hg; P=0. 001) and cardiac output (coefficient=0.001 cm(2)xmin/L; P=0.002). The strongest predictor of cardiac output was LA reservoir filling (coefficient=301 L/minxcm(2); P<0.001). The v loop area was determined by cardiac output, LV ejection time, tau, and early transmitral flow. CONCLUSIONS: Two (early and late) reservoir phases are determined by LA contraction and relaxation and LV base descent. Acute LV regional ischemia increases LA stiffness and impairs LA reservoir function by reducing LV base descent.

Sonospirometry: a new method for noninvasive estimation of mean right atrial pressure based on two-dimensional echographic measurements of the inferior vena cava during measured inspiration.

A noninvasive method of estimating mean right atrial pressure would be useful in evaluating hemodynamics and calculating pulmonary pressures by Doppler echocardiography. An electronic pressure gauge was built and tested for measurement of inspiratory pressures during two-dimensional echocardiography to quantitate the diameter of the inferior vena cava. Thirty-one studies were made in 27 alert, informed, consenting patients with an in-place pulmonary artery catheter having right atrial ports. Inferior vena cava diameter was measured in successive 10 mm segments distal to the right atrial-inferior vena cava junction on images obtained while the patient suspended breathing at full inspiration and during each 4 mm Hg increment of a calibrated inspiratory maneuver. Results show that the segment between 5 and 30 mm distal to the right atrial-inferior vena cava junction was the region most responsive to increasing inspiratory pressure. In this segment, the inspiratory pressure required to decrease the inferior vena cava diameter to greater than or equal to 85% of the difference between its maximal (suspended full inspiration) and minimal (over the entire inspiratory maneuver) values was similar or equal to the mean right atrial pressure (measured from the pulmonary artery catheter) (r = 0.87, SEE = 2.9 mm Hg). Minimal inferior vena cava diameter was directly related to mean right atrial pressure (r = 0.56); the minimal to maximal inferior vena cava diameter ratio was inversely related to mean right atrial pressure (r = -0.57). Maximal inferior vena cava diameter and the absolute (measured) amount of inferior vena cava diameter decrease correlated weakly with mean right atrial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Guidelines for physician training in advanced cardiac procedures: the importance of case mix.

In recent years, guidelines have been issued for the standardization of physician training in various advanced cardiac procedures. One area that is often neglected by guidelines committees is the need for an adequate case mix during physician training. Case mix refers to the variety of patients and diseases that the trainee is exposed to during the course of learning a new procedure. Although physicians may perform the requisite number of procedures during their training, if the case mix is inadequate, the physician's competence in performing the procedure and interpreting its results may be inadequate as well.

Peak mitral inflow velocity predicts mitral regurgitation severity.

OBJECTIVES: Mitral regurgitation (MR) is a common echocardiographic finding; however, there is no simple accurate method for quantification. The aim of this study was to develop an easily measured screening variable for hemodynamically significant MR. BACKGROUND: The added regurgitant volume in MR increases the left atrial to left ventricular gradient, which then increases the peak mitral inflow or the peak E wave velocity. Our hypothesis was that peak E wave velocity and the E/A ratio increase in proportion to MR severity. METHODS: We performed a retrospective analysis of 102 consecutive patients with varying grades of MR seen in the Adult Echocardiography Laboratory at the University of California, San Francisco. Peak E wave velocity, peak A wave velocity, E/A ratio and E wave deceleration time were measured in all patients. The reference standard for MR was qualitative echocardiographic evaluation by an expert and quantitation of regurgitant fraction using two-dimensional and Doppler echocardiography. RESULTS: Peak E wave velocity was seen to increase in proportion to MR severity, with a significant difference between the different groups (F = 37, p < 0.0001). Peak E wave velocity correlated with regurgitant fraction (r = 0.52, p < 0.001). Furthermore, an E wave velocity >1.2 m/s identified 24 of 27 patients with severe MR (sensitivity 86%, specificity 86%, positive predictive value 75%). An A wave dominant pattern excluded the presence of severe MR. The E/A ratio also increased in proportion to MR severity. Peak A wave velocity and E wave deceleration time showed no correlation with MR severity. CONCLUSIONS: Peak E wave velocity is easy to obtain and is therefore widely applicable in clinical practice as a screening tool for evaluating MR severity.

Active compression-decompression resuscitation: analysis of transmitral flow and left ventricular volume by transesophageal echocardiography in humans. Cardiopulmonary Resuscitation Working Group.

OBJECTIVES: This study was designed to test the hypothesis that active compression-decompression cardiopulmonary resuscitation increases transmitral flow and end-decompression left ventricular volume over levels achieved with standard manual cardiopulmonary resuscitation. BACKGROUND: Recently, cardiopulmonary resuscitation incorporating active compression and decompression of the chest has been demonstrated to improve hemodynamic status in a canine model and in humans after cardiac arrest. METHODS: The active compression-decompression device was applied midsternum in five consecutive patients and results compared sequentially (in random order) with those of standard manual cardiopulmonary resuscitation. Both techniques were performed at 80 compressions/min with a 1.5- to 2-in. (3.8 to 5.1 cm) compression depth and a 50% duty cycle. Transesophageal echocardiographic data obtained in each patient included the velocity-time integral of transmitral pulsed Doppler recordings and two-dimensional images of the left ventricle in the long-axis view. Planimetric volume measurements of the left ventricle were obtained at both end-compression and end-decompression. RESULTS: No difference was observed in end-compression volume between the two techniques (p = 0.81). Increased end-decompression volume (active compression-decompression technique 81.3 +/- 12.5 vs. standard technique 69.4 +/- 10.8, p < 0.05), stroke volume (active compression-decompression technique 32.6 +/- 6.8 vs. standard technique 17.6 +/- 5.2, p < 0.05) and velocity-time integral of transmitral flow (active compression-decompression technique 15.8 +/- 4.3 vs. standard technique 7.8 +/- 2.3, p < 0.05) were found in the active compression-decompression group. The transmitral velocity-time integral was highly correlated with left ventricular stroke volume (r = 0.90). CONCLUSIONS: Improved transmitral flow, end-decompression left ventricular volume and stroke volume are seen with active compression-decompression resuscitation, suggesting a biphasic cardiothoracic cycle of flow. Active decompression of the chest appears to be a beneficial adjunct to standard cardiopulmonary resuscitation.

Transesophageal echocardiographically detected atherosclerotic aortic plaque is a marker for coronary artery disease.

OBJECTIVES: The aim of this study was to test the hypothesis that atherosclerotic plaque in the thoracic aorta detected by transesophageal echocardiography is a marker for coronary artery disease. BACKGROUND: Previous pathologic and roentgenographic studies have suggested a relation between aortic plaque and coronary artery disease but have lacked clinical utility. METHODS: We performed transesophageal echocardiography on 61 patients (30 women and 31 men aged 22 to 83 years [mean 60 +/- 14]) who had previously undergone cardiac catheterization with coronary angiography. The clinical indications for angiography were angina (n = 26), valvular heart disease (n = 17), positive noninvasive evaluation for ischemia without angina (n = 6), postmyocardial infarction (n = 5), familial hypercholesterolemia (n = 4), coronary cameral fistula (n = 1), atrial myxoma (n = 1) and suspected aortic dissection (n = 1). All patients underwent transesophageal echocardiography with imaging of the thoracic aorta. The criteria used to diagnose atherosclerotic plaque on transesophageal echocardiography were the presence of linear or focal increased echo-density with lumen irregularity and thickening or calcification of the aortic intima. RESULTS: In 41 of the 61 patients, obstructive coronary artery disease was detected by angiography in at least one vessel (> 50% left main coronary artery stenosis or > 70% stenosis in the left anterior descending, right coronary or left circumflex artery distribution). In 37 of the 41, atherosclerotic plaque was detected in the thoracic aorta by transesophageal echocardiography. Twenty of the 61 patients had normal coronary angiographic findings or nonobstructive lumen irregularities. In 2 of these 20 patients, plaque was detected in the thoracic aorta on transesophageal echocardiography. The presence of aortic plaque on transesophageal study had a sensitivity of 90% and a specificity of 90% for angiographically proved obstructive coronary artery disease. The positive predictive value of aortic plaque for obstructive coronary artery disease was 95% and the negative predictive value was 82%. CONCLUSIONS: The detection of atherosclerotic plaque in the thoracic aorta by transesophageal echocardiography appears to be a marker for the identification of obstructive coronary artery disease and deserves further investigation.

Determinants of forward pulmonary vein flow: an open pericardium pig model.

OBJECTIVE: To elucidate determinants of pulmonary venous (PV) flow. BACKGROUND: Right ventricular (RV) systolic pressure (vis a tergo), left atrial (LA) relaxation and left ventricular (LV) systole and relaxation (vis a fronte) have been suggested as determinants of the pulmonary venous (PV) anterograde Doppler flow velocities, but their relative contributions to those flow velocities have not been quantified. METHODS: We analyzed, by multiple regression analysis, the determinants of PV anterograde velocities in an open-pericardium, paced (70 and 90 beats/min) pig model in which LA afterload was modified by creating LV regional ischemia (left anterior descending coronary artery constriction). We measured high fidelity LA, LV and RV pressures and Doppler flow velocities (epicardial echocardiography). We calculated LV tau, LA relaxation (a through x pressure difference divided by time, normalized by a pressure), LA peak v through x and RV systolic through LA peak v (RVSP-v) pressure differences, LV ejection fraction, long-axis shortening, stroke volume (LV outflow integral x outflow area) and LA four-chamber dimensions, Doppler transmitral and PV flow velocities and velocity-time integrals. RESULTS: Left ventricular regional ischemia increased mildly LA y trough pressure (8 +/- 1 vs. 6 +/- 1 mm Hg, p = 0.001). Left ventricular stroke volume (coefficient: 0.5 cm/ml, SE: 0.2, p = 0.005) and LA peak v pressure (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.008) determined the PV total systolic integral. Left atrial relaxation determined both PV early systolic peak velocity and integral (coefficient: -0.8 cm/mm Hg, SE: 0.3, p = 0.04). Left atrial maximum area (coefficient: 2 cm(-1) SE: 0.7, p = 0.01) and RVSP-v (coefficient: 0.1 cm/mm Hg, SE: 0.05, p = 0.03) determined the late systolic integral. The PV total systolic integral determined both PV early diastolic peak velocity and integral (coefficient: 1.2, SE: 0.2, p = 0.001). CONCLUSIONS: In an experimental model of LV acute ischemia of limited duration, the main independent predictors of PV systolic anterograde flow velocities are LA relaxation and compliance (LA peak v pressure) and LV systole--all vis a fronte factors. In the setting of mildly increased LA pressures, PV systolic flow (LA reservoir filling) is an independent predictor of PV early diastolic flow (LA early conduit).

Demonstration of postvalvuloplasty hemodynamic improvement in aortic stenosis based on Doppler measurement of valvular resistance.

It was recently suggested that valvular resistance, defined as the pressure gradient/flow rate ratio, may better depict the hemodynamic impairment in aortic stenosis than does valve area. The relation between aortic valve resistance and left ventricular mechanics was studied with Doppler echocardiography in 13 patients (mean age 85 years) with severe aortic stenosis who underwent percutaneous balloon valvuloplasty. The Doppler-estimated peak valvular resistance, defined as the ratio of peak transvalvular pressure gradient to peak valvular flow rate, decreased from 510 +/- 190 dynes.s.cm-5 before valvuloplasty to 300 +/- 110 dynes.s.cm-5 after the procedure (p = 0.0001). There was a close linear relation between valvular resistance measured at catheterization and Doppler-derived peak valvular resistance (r = 0.91). After valvuloplasty, left ventricular ejection fraction increased from 53 +/- 13% to 62 +/- 11% (p = 0.0001). The percent increase in ejection fraction was linearly related to the percent decrease in end-systolic wall stress (r = 0.56), which was in turn related to the percent decrease in peak valvular resistance (r = 0.75). No such linear relation existed between the percent changes in valve area and those in end-systolic wall stress. In conclusion, hemodynamic improvement after valvuloplasty is more closely related to changes in valvular resistance than to changes in valvular area. It is suggested that valvular resistance can be estimated accurately by Doppler echocardiography with use of a simple method and should be a primary consideration in assessing the hemodynamics of aortic stenosis.

The Mitral Regurgitation Index: an echocardiographic guide to severity.

OBJECTIVES: The purpose of this study was to develop a semiquantitative index of mitral regurgitation severity suitable for use in daily clinical practice and research. BACKGROUND: There is no simple method for quantification of mitral regurgitation (MR). The MR Index is a semiquantitative guide to MR severity. The MR Index is a composite of six echocardiographic variables: color Doppler regurgitant jet penetration and proximal isovelocity surface area, continuous wave Doppler characteristics of the regurgitant jet and tricuspid regurgitant jet-derived pulmonary artery pressure, pulse wave Doppler pulmonary venous flow pattern and two-dimensional echocardiographic estimation of left atrial size. METHODS: Consecutive patients (n = 103) with varying grades of MR, seen in the Adult Echocardiography Laboratory at UCSF, were analyzed retrospectively. All patients were evaluated for the six variables, each variable being scored on a four point scale from 0 to 3. The reference standards for MR were qualitative echocardiographic evaluation by an expert and quantitation of regurgitant fraction using two-dimensional and Doppler echocardiography. A subgroup of patients with low ejection fraction (EF < 50%) were also analyzed. RESULTS: The MR Index increased in proportion to MR severity with a significant difference among the three grades in both normal and low EF groups (F = 130 and F = 42, respectively, p < 0.0001). The MR Index correlated with regurgitant fraction (r = 0.76, p < 0.0001). An MR Index > or =2.2 identified 26/29 patients with severe MR (sensitivity = 90%, specificity = 88%, PPV = 79%). No patient with severe MR had an MR Index <1.8 and no patient with mild MR had an MR Index >1.7. CONCLUSIONS: The MR Index is a simple semiquantitative estimate of MR severity, which seems to be useful in evaluating MR in patients with a low EF.

Left ventricular volumes determined by two-dimensional echocardiography in a normal adult population.

The purpose of this study was to determine normal population volume variables of the left ventricle as determined by different algorithms currently available. Two-dimensional echocardiography was prospectively performed on 52 normal volunteers to determine normal left ventricular volume and ejection fraction as a prerequisite to their clinical application. All echocardiograms were performed using a commercially available two-dimensional phased array sector scanner. Three algorithms were applied to three views in various combinations. Ejection fraction calculations were found to be reliable, reproducible and independent of the algorithm employed. Left ventricular volumes were larger in men than in women (probability [p] less than 0.005) despite correcting for body surface area, indicating the need for separating patients according to sex. The Simpson's rule algorithm resulted in smaller values for left ventricular volume than did any of the area-length algorithms and the data were the most reproducible as judged by intraobserver variation. The single plane area-length methods are clinically useful because they are simple, rapid to execute and reliable. Ejection fraction calculation was independent of the algorithm employed.

Inferior vena cava plethora with blunted respiratory response: a sensitive echocardiographic sign of cardiac tamponade.

To assess the diagnostic and prognostic value of the respiratory behavior of the inferior vena cava in pericardial effusions, clinical and two-dimensional echocardiographic data of 115 consecutive patients with a moderate or large effusion, including 33 who had cardiac tamponade, were reviewed. Echocardiograms were reviewed for effusion size, inferior vena cava diameter before and after deep inspiration and presence of right atrial and ventricular collapse. For the 83 patients (72%) with less than 50% decrease in inferior vena cava diameter after deep inspiration ("plethora"), inferior vena cava diameter decreased from 2.0 +/- 0.3 to 1.6 +/- 0.4 cm after inspiration (mean +/- SD) (mean decrease 18%). For the 32 patients (28%) without plethora, the diameter decreased from 1.6 +/- 0.5 to 0.6 +/- 0.3 cm (mean decrease 63%). Patients with plethora had significantly higher values for heart rate (111 +/- 21 versus 98 +/- 20 beats/min), pulsus paradoxus (24 +/- 15 versus 12 +/- 4 mm Hg), jugular venous distension (14 +/- 5 versus 8 +/- 3 cm H2O) and right atrial pressure (17 +/- 6 versus 12 +/- 6 mm Hg) and lower values for systolic blood pressure (109 +/- 22 versus 132 +/- 27 mm Hg) (all p less than 0.05) than did patients without plethora. Plethora was present in 58 (92%) of 63 patients who underwent a pericardial drainage procedure, 14 (88%) of 16 who developed constrictive physiology and 11 (92%) of 12 of those whose hospital death was related to pericardial effusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular function immediately after intravenous cocaine: a quantitative two-dimensional echocardiographic study.

OBJECTIVES: We tested the hypothesis that intravenous cocaine, in doses commonly self-administered in nonmedical settings, causes acute myocardial ischemia and left ventricular dysfunction. BACKGROUND: Cocaine-induced cardiac complications are responsible for a growing number of deaths in young people, but the mechanism by which cocaine induces these complications is unclear. METHODS: We performed 12-lead electrocardiography and quantitative two-dimensional echocardiography in 20 subjects before and after single intravenous doses of high dose cocaine (1.2 mg/kg body weight), low dose cocaine (0.6 mg/kg) and placebo. RESULTS: At 2 to 7 min after cocaine administration, the rate-pressure product was increased significantly from baseline (high dose 73%, low dose 63%, placebo 8%, p < 0.001 for either dose vs. placebo). During this time, electrocardiography demonstrated dose-related nonspecific changes (high dose in 14 of 20 subjects, low dose in 9 of 20 subjects, placebo in 2 of 20 subjects, p < 0.002 for either dose vs. placebo). In contrast, echocardiography showed that the frequency of hyperdynamic left ventricular wall segments doubled after high dose cocaine compared with placebo (34% [108 of 318] vs. 16% [51 of 319], respectively, p = 0.0001) but that there was no change in either left ventricular ejection fraction (high dose 66 +/- 9%, placebo 67 +/- 6%, p = NS) or wall motion score index (high dose 0.67 +/- 0.44, placebo 0.85 +/- 0.30, p = NS). CONCLUSIONS: We conclude that intravenous cocaine, in doses commonly self-administered in nonmedical settings, does not cause acute myocardial ischemia or left ventricular dysfunction. We speculate that cocaine-induced cardiac complications are caused by idiosyncratic coronary artery vasospasm, by exceptionally high dosages or by cocaine-induced coronary artery thrombosis.

Diagnostic value of chest radiography for pericardial effusion.

OBJECTIVES: This study was designed to determine the diagnostic value of chest radiography for pericardial effusion. BACKGROUND: Pericardial effusions may cause life-threatening cardiac complications, yet they are often difficult to diagnose. METHODS: In a blinded manner, we reviewed the chest radiographs of 83 patients with echocardiographically diagnosed pericardial effusions (5 large, 18 moderate, 60 small) and those of 17 control subjects without effusions. We examined four radiographic signs: an enlarged cardiac silhouette, a pericardial fat stripe, a predominant left-sided pleural effusion and an increase in transverse cardiac diameter compared with the diameter on a previous chest radiograph. RESULTS: An enlarged cardiac silhouette was moderately sensitive (71%) but not specific (41%) for pericardial effusion. A pericardial fat stripe, a predominant left-sided pleural effusion and an increase in transverse cardiac diameter were all specific (94%, 100% and 80%, respectively) but not sensitive (12%, 20% and 46%, respectively). A predominant left-sided pleural effusion was associated with pericardial effusions of all sizes (odds ratio = 1.3, 95% confidence interval [CI] = 1.0-1.6, p = 0.04) and with large and moderate pericardial effusions alone (odds ratio = 7.7, 95% CI = 2.5-24.0, p = 0.0004). In contrast, a pericardial fat stripe was associated only with large and moderate pericardial effusions (odds ratio = 3.3, 95% CI = 0.9-12.0, p = 0.07), and an enlarged cardiac silhouette and an increase in cardiac diameter were not associated with pericardial effusion at all. CONCLUSIONS: A predominant left-sided pleural effusion and a pericardial fat stripe are chest radiographic signs that are suggestive, but not diagnostic, of pericardial effusion. Because these signs cannot reliably confirm or exclude the presence of pericardial effusion, we conclude that chest radiography is poorly diagnostic of this condition.

Response of the interatrial septum to transatrial pressure gradients and its potential for predicting pulmonary capillary wedge pressure: an intraoperative study using transesophageal echocardiography in patients during mechanical ventilation.

OBJECTIVES: We hypothesized that the directional movement of the interatrial septum and its curvature may reflect the pressure relations between the left and right atria. BACKGROUND: Interventricular septal shape is primarily dependent on the pressure gradient between the left and the right ventricle. No analogous study has carefully evaluated the determinants of interatrial septum shape and motion. METHODS: Patients (n = 52) undergoing cardiac or vascular surgery were studied intraoperatively at multiple intervals with transesophageal echocardiography and simultaneous measurement of central venous pressure, pulmonary capillary wedge pressure and airway pressure. RESULTS: Overall interatrial septum shape, which usually curved toward the right atrium, changed concordantly with the interatrial pressure gradient (pulmonary capillary wedge pressure-central venous pressure difference). The degree of interatrial septum curvature was also primarily dependent on the interatrial pressure gradient and, to a lesser extent, was affected by changes in left atrial size (F = 130.4 vs. F = 14.1). During passive mechanical expiration, the interatrial pressure gradient, usually positive, often reverses transiently and the interatrial septum momentarily bows toward the left atrium. Midsystolic reversal was seen in 64 of 72 episodes when the pulmonary capillary wedge pressure was < or = 15 mm Hg but in only 2 of 40 episodes when it was > 15 mm Hg (sensitivity = 0.89, specificity = 0.95, positive predictive value = 0.97). CONCLUSIONS: These findings suggest that overall interatrial septum shape depends on the pressure gradient between the left and right atria. Midsystolic reversal of the interatrial septum, which probably reflects the increased venous return in the right relative to the left atrium during mechanical expiration, may be a useful indicator of the pulmonary capillary wedge pressure.

Diagnostic value of transesophageal compared with transthoracic echocardiography in infective endocarditis.

To compare the diagnostic value of transesophageal and transthoracic echocardiography in infective endocarditis, paired transesophageal and transthoracic echocardiograms were obtained prospectively for 66 episodes of suspected endocarditis in 62 patients. Echocardiographic results were compared with the presence or absence of endocarditis determined by pathologic or nonechocardiographic data from the subsequent clinical course. All echocardiograms were interpreted by an observer told only that the studies were from patients in whom the diagnosis of endocarditis was suspected. The diagnosis of endocarditis was eventually made in 16 of the 66 episodes of suspected endocarditis (14 by pathologic and 2 by clinical criteria). In 7 of 16 transthoracic and 15 of 16 transesophageal echocardiograms, endocarditis was diagnosed at a probability level of "almost certain," giving a sensitivity of 44% and 94%, respectively (p less than 0.01). For the remaining episodes, 49 of 50 transthoracic and all transesophageal studies yielded normal results, giving a specificity of 98% and 100%, respectively. This study suggests that transesophageal echocardiography is highly sensitive and specific for the diagnosis of infective endocarditis and significantly more sensitive than transthoracic echocardiography. Although echocardiography cannot rule out endocarditis, the high diagnostic sensitivity of transesophageal echocardiography results in a low probability of the disease when the study yields negative results in a patient with an intermediate likelihood of the disease.

Measurement of aortic blood flow by Doppler echocardiography: day to day variability in normal subjects and applicability in clinical research.

To assess the reliability of Doppler ultrasound for detecting serial changes in cardiac output in response to experimental interventions, the day to day variability of the minute distance of aortic flow was determined in seven normal subjects maintained in a tightly controlled environment with regard to diet and activities. Measurements were made at the same time on 5 to 6 sequential days from an apical window with use of both continuous wave and pulsed wave Doppler techniques. Two statistical measures of reliability were calculated, the intraclass coefficient of correlation (R), which varies between 0 (null reliability) and +1 (perfect reliability), and the 95% confidence interval for the error-free value of a single measurement. For sequential measurements of arterial pressure, 24 h urinary volume and sodium excretion and body weight, the intraclass coefficients of correlation ranged from 0.85 to 0.99, indicating low day to day variability consistent with tight environmental control. Continuous and pulsed wave modes were proved equally and highly reliable for measuring minute distance of aortic flow. However, continuous wave Doppler ultrasound provided acceptable signals more frequently than did the pulsed wave technique. For continuous wave Doppler ultrasound, R was 0.87 (p less than 0.00001); the 95% confidence interval was +/- 1.81 m/min (or 11% of the mean of all measurements), which indicates that this method can be used in a single individual to detect a greater than 11% change in minute distance measured once before and after an intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Transesophageal echocardiography predicts mortality in critically ill patients with unexplained hypotension.

OBJECTIVES: This study sought to determine the prognostic yield and utility of transesophageal echocardiography in critically ill patients with unexplained hypotension. BACKGROUND: Transesophageal echocardiography is increasingly utilized in the intensive care setting and is particularly suited for the evaluation of hypotension; however, the prognostic yield of transesophageal echocardiography in these patients is unknown. METHODS: We prospectively studied 61 adult patients in the intensive care unit with sustained (> 60 min) unexplained hypotension. Both transthoracic and transesophageal echocardiography were performed, and results were immediately disclosed to the primary physician, who reported any resulting changes in management. Patients were classified on the basis of transesophageal echocardiographic findings into one of three prognostic groups: 1) nonventricular (valvular, pericardial) cardiac limitation to cardiac output; 2) ventricular failure; and 3) noncardiac systemic disease (hypovolemia or low systemic vascular resistance, or both). Primary end points were death or discharge from the intensive care unit. RESULTS: A transesophageal echocardiographic diagnosis of nonventricular limitation to cardiac output was associated with improved survival to discharge from the intensive care unit (81%) versus a diagnosis of ventricular disease (41%) or hypovolemia/low systemic vascular resistance (44%, p = 0.03). Twenty-nine (64%) of 45 transthoracic echocardiographic studies were inadequate compared with 2 (3%) of 61 transesophageal echocardiographic studies (p < 0.001). Transesophageal echocardiography contributed new clinically significant diagnoses (not seen with transthoracic echocardiography) in 17 patients (28%), leading to operation in 12 (20%). CONCLUSIONS: Transesophageal echocardiography makes a clinically important contribution to the diagnosis and management of unexplained hypotension and predicts prognosis in the critical care setting.

Evaluation of electrocardiographic criteria for right atrial enlargement by quantitative two-dimensional echocardiography.

OBJECTIVES: This study was conducted to evaluate the sensitivity and specificity of traditional electrocardiographic (ECG) criteria for right atrial enlargement and identify improve criteria, using quantitative two-dimensional echocardiography. BACKGROUND: Traditional ECG criteria for right atrial enlargement, such as P pulmonale, have been increasingly criticized as insensitive and nonspecific. Quantitative two-dimensional echo-cardiography has been shown to be a useful method for evaluating atrial size. METHODS: Hospitalized patients with mild, moderate and severe right atrial enlargement were selected from our laboratory's data base and compared with age- and gender-correlated hospitalized control subjects. After exclusions, 100 patients with right atrial enlargement and 25 control patients remained. Planimetric measurement of right atrial volumes was accomplished by two independent observers using the single-plane method of discs algorithm. Electrocardiograms were independently evaluated for current and newly proposed right atrial enlargement criteria. RESULTS: Fifty-two patients (52%) were in sinus rhythm, 41 were in atrial fibrillation, 5 were in atrial flutter, and 2 were in ectopic atrial rhythm. All control subjects were in sinus rhythm. The right atrial volume for the control group was 35.0 +/- 7.4 ml (mean +/- SD), with a narrow, roughly normal distribution. The right atrial volume for the patient group was 147.6 +/- 69.1 ml (median 127.2) in a wide, skewed distribution. The difference of mean values was highly significant (p = 0.0001). Right ventricular enlargement was found to some degree in all patients with right atrial enlargement. The most powerful predictors of right atrial enlargement were a QRS axis > 90 degrees, a P wave height in lead V2 > 1.5 mm and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. P pulmonale detected only 6% of patients with right atrial enlargement. CONCLUSIONS: Using quantitative two-dimensional echocardiography, we found that most previously reported ECG criteria for right atrial enlargement have low predictive power. The best predictors of right atrial enlargement were a P wave height > 1.5 mm in lead V2 and, as new criteria, a QRS axis > 90 degrees and an R/S ratio > 1 in lead V1 in the absence of complete right bundle branch block. The combined sensitivity of these three criteria was 49%, with preservation of 100% specificity. Further studies are needed to prospectively validate these findings.

Measurement of left ventricular stroke volume using continuous wave Doppler echocardiography of the ascending aorta and M-mode echocardiography of the aortic valve.

A number of reports have described different Doppler echocardiographic methods to calculate left ventricular stroke volume and cardiac output, but the clinical application of the noninvasive measurements of cardiac function remains in the early stages of development. This slow dissemination may be partly explained by the varying success of these ultrasound methods in determining accurate left ventricular stroke volume. The purpose of this study was to improve the simplicity and accuracy of Doppler stroke volume determination so that it could be more easily applied to patient management. Stroke volume was measured using the product of the integral of aortic velocity obtained by continuous wave Doppler technique and the M-mode tracing of the aortic valve, validating the data against cardiac output obtained by thermodilution technique in 41 patients (r = 0.95, SEE = 7 cc). Intra- and interobserver variability was between 9 and 11%. The results of different sampling sites and the temporal relation between Doppler and thermodilution measurements were also studied. Analysis of 21 patients who had M-mode and two-dimensional echocardiographic studies of the aortic root revealed that the method using M-mode measurement of aortic valve area was most accurate in determining left ventricular stroke volume (r = 0.94, SEE = 10 cc), stroke volume being overestimated when area measurements of the ascending aorta were used. In conclusion, maximal ascending aortic velocity determined by continuous wave Doppler echocardiography with M-mode measurement of aortic valve area can be used to calculate left ventricular stroke volume and cardiac output. The simplicity and practicality of this method should enhance the clinical application of Doppler echocardiography as a noninvasive monitoring technique.

Cardiac manifestations of human immunodeficiency virus infection: a two-dimensional echocardiographic study.

To determine the prevalence of cardiac abnormalities in patients with human immunodeficiency virus (HIV) infection, two-dimensional Doppler echocardiography was performed on 70 consecutive patients with HIV infection, including 51 with acquired immunodeficiency syndrome (AIDS), 13 with AIDS-related complex and 6 with asymptomatic HIV infection. Of the 70 patients, 36% were hospitalized and 64% were ambulatory at the time of evaluation. The average age was 37 years; 93% were homosexual men. Echocardiographic findings included dilated cardiomyopathy in eight patients (11%), pericardial effusions in seven patients (10%) (one with impending tamponade), pleural effusion in four patients (6%) and mediastinal mass in one patient (1%). Among the 25 hospitalized patients, echocardiographic abnormalities were noted in 16 (64%), whereas among the 45 ambulatory patients, the only abnormality noted was mitral valve prolapse in 3 patients (7%) (p less than 0.0001). Dilated cardiomyopathy was the only echocardiographic lesion more common in the 25 hospitalized patients than in 20 hospitalized control patients with acute leukemia. Symptoms of congestive heart failure responded to conventional therapy. Cardiac lesions were associated with active Pneumocystis carinii pneumonia and low T helper lymphocyte counts. Dilated cardiomyopathy of unknown origin may be more common than was previously recognized in hospitalized, acutely ill patients with AIDS, but is uncommon in ambulatory patients with HIV infection. Echocardiography should be considered in the evaluation of dyspnea in hospitalized patients with HIV infection, especially those with dyspnea that is out of proportion to the degree of pulmonary disease.