Molecular rectification induced by magnetization alignment in organic-ferromagnetic devices.

Spin-dependent transport in ferromagnet/organic-ferromagnet/ferromagnet junctions is investigated theoretically under different alignment of magnetization orientations. The results demonstrate a significant current rectification at low bias voltages, and the rectifying direction relies on the relative magnetization orientation in each component. The orbital analysis demonstrates two underlying mechanisms for the rectification, the slight structural asymmetry of the molecule from spin radicals and distinct spin match between conducting electrons and the magnetic molecule upon the reversal of bias. The latter is responsible for the strong low-bias rectification and relies on the magnetization alignment. The effects of parameter strength, temperature and size on the rectification are discussed. This work explores a new route to achieve high-performance molecular rectifiers operating at low bias with controlled rectifying direction.

[The relationship between rapid eye movement electromyogram activity and sleep stability in rapid eye movement sleep behavior disorder].

Objective: To investigate the relationship between the types of electromyogram (EMG) activity and sleep stability during rapid eye movement (REM) in patients with rapid eye movement sleep behavior disorder(RBD). Methods: One hundred and three patients with RBD who met the inclusion and exclusion criteria at the Second Affiliated Hospital of Air Force Military Medical University from January 2017 to December 2019 were retrospectively analyzed. The general situation, clinical symptoms, sleep and emotion questionnaires and nocturnal PSG data were collected. According to the different proportions of tonic and phasic EMG activity, the group with a higher proportion of tonic EMG than phasic EMG was defined as the tonic dominant group, and the group with a higher proportion of phasic EMG than tonic was defined as the phasic dominant group. The sleep instability index was calculated according to the ratio of the number of transitions from sleep to wakefulness to the total sleep time of each sleep stage. Multiple linear regression was used to explore the relationship between REM EMG activity and sleep instability index. Results: A total of 35 idiopathic RBD (iRBD) patients were included, aged(54.5±18.2)years, with 17 males and 18 females. There were 27 RBD with Parkinson's disease (PD), with an average age of (59.4±7.9)years, including 17 males and 10 females. Additionally, there were 41 RBD patients with narcolepsy, aged (21.2±13.2)years, consisting of 22 males and 19 females. Both iRBD and RBD patients with PD had lower objective total sleep time, sleep latency, sleep efficiency, wake time after sleep onset and the percentage of N3 sleep compared to RBD with episodic sleep disorder (all P<0.05). N1-W index[M(Q1, Q3),10.6 (6.5, 16.9)/h vs 7.3 (4.7, 10.5)/h], N2-W index [4.0 (2.2, 5.6)/h vs 2.3 (1.5, 3.9)/h], NREM-W index [ (5.8±2.9)/h vs (4.5±3.2)/h] and REM-W index[ 3.9 (1.9, 7.3)/h vs 2.7 (1.0, 4.0)/h] in the phasic dominant group were higher than those in the tonic dominant group. After adjusting for confounding factors, the effect of phasic EMG dominant group on REM-W was higher than that in the tonic dominant group (ß=2.05, 95%CI: 0.09-3.26, P=0.012). Conclusion: In RBD patients, the phasic EMG activity has a significant impact on sleep stability, especially on REM sleep stability.

[Effects of different accompanying symptoms of obstructive sleep apnea on the risk of cardiovascular and cerebrovascular and diabetes events].

Objective: To investigate the effects of different accompanying symptoms on the risk of cardiovascular and cerebrovascular and diabetes events in patients with obstructive sleep apnea (OSA). Methods: Patients diagnosed with OSA in the sleep center of Tangdu Hospital from January 4, 2011 to December 28, 2016 were retrospectively collected and divided into four groups according to accompanying symptoms: group A included OSA patients without insomnia and excessive daytime sleepiness (EDS), group B included OSA patients with insomnia, group C included OSA patients with EDS and group D included OSA patients with insomnia and EDS. Patients were followed up by telephone for 6 to 11 years. Outcome measures were composite cardiovascular and cerebrovascular and diabetes events (including new onset or recurrent heart disease, cerebral infarction, cerebral hemorrhage, newly diagnosed hypertension and diabetes). Kaplan-Meier method was used to draw survival curves, log-rank test was performed to compare the prognosis of OSA patients with insomnia and/or EDS symptoms, and multivariate Cox proportional hazards model was constructed to analyze the influencing factors of adverse outcome events in OSA patients. Results: Five hundred and four patients with OSA were included, and 307 patients [274 males and 33 females, aged (49±11) years] completed the follow-up, including 27 patients in group A, 143 patients in group B, 27 patients in group C, and 110 patients in group D. After a median follow-up of 7.7 years, 78 patients developed cardiovascular and cerebrovascular and diabetes events. Outcome events occurred in 1 patient (3.70%) in group A, 30 (20.98%) in group B, 10 (37.04%) in group C, and 37 (33.64%) in group D. Compared with patients in group A, there was a statistically significant difference in the incidence of outcome events in groups B (P=0.034), C (P=0.004), and D (P=0.003). After adjusting for age, sex, body mass index, apnea-hypopnea index, baseline cardiovascular and cerebrovascular risk factors and subsequent continuous positive airway pressure therapy, patients in group C (HR=9.67, 95%CI: 1.23-76.37, P=0.031) and group D (HR=11.35, 95%CI: 1.55-83.43, P=0.017) had an increased risk of cardiovascular and cerebrovascular and diabetes events when compared with group A. Conclusions: In OSA patients with successful long-term follow-up, insomnia and EDS symptoms are risk factors for the development of cardiovascular and cerebrovascular and diabetes events. Insomnia and EDS symptoms should be evaluated in patients with OSA during clinical practice to find the cause and carry out the targeted intervention.

Enhanced Intrinsic Anomalous Valley Hall Effect Induced by Spin-Orbit Coupling in MXene Monolayer M3N2O2 (M = Y, La).

The limitation of suitable anomalous valley Hall effect (AVHE) materials has seriously hindered the booming development and the widespread application of valleytronics. Here, through the first-principles calculations, we propose a MXene monolayer Y3N2O2 with spontaneous valley polarization (VP) of 21.3 meV, which induces intrinsic AVHE. The VP can be modulated linearly, which provides a route of effective control of the valley signals. Importantly, VP can be enhanced by adjusting up the spin-orbit coupling (SOC) based on a SOC Hamiltonian model and the first-principles calculations. From this physics underlying, we substitute the Y atom with the La atom and further propose the monolayer La3N2O2, in which the heavy atom La will provide stronger SOC than Y atom. The spontaneous VP in La3N2O2 is enhanced to 100.4 meV, so AVHE can be easily achieved. Our work not only provides compelling candidates for AVHE materials but also offers a novel mindset for finding suitable valleytronic devices.

Type-II Band Alignment and Tunable Optical Absorption in MoSSe/InS van der Waals Heterostructure.

In this work, we study the electronic structure, the effective mass, and the optical properties of the MoSSe/InS van der Waals heterostructures (vdWHs) by first-principles calculations. The results indicate that the MoSSe/InS vdWH is an indirect band gap semiconductor and has type-Ⅱ band alignment in which the electrons and holes located at the InS and the MoSSe side, respectively. The band edge position, the band gap and the optical absorption of the MoSSe/InS vdWH can be tuned when biaxial strains are applied. In addition, compared with MoSSe and InS monolayers, the optical absorption of the MoSSe/InS vdWH is improved both in the visible and the ultraviolet regions. These findings indicate that the MoSSe/InS vdWHs have potential applications in optoelectronic devices.

Tuning electronic and optical properties of monolayer PdSe2 by introducing defects: first-principles calculations.

Based on the density functional theory, the electronic and optical properties of pristine monolayer PdSe2 with Pd or Se vacancy-defect are investigated. Our results show that the Se defect is energetically more favorable than that of Pd defect. The band gap reduces, and some new midgap states appear after the Pd or Se defects are introduced. In terms of the optical properties, the prominent anisotropic characters are remained. The obvious new peaks of the dielectric constant appear after introducing defects. The light absorption in the visible energy range expands based on the appearance of the midgap states induced by the Pd or Se defects. The changes of the refractive index and reflectivity are similar with those of the dielectric constants and the light absorption. The energy loss spectrum of the PdSe2 with Pd or Se defects is obviously different, which can be used to identify different defects in PdSe2. These findings provide effective strategies to tune electronic and optical properties of monolayer PdSe2 by introducing defects.

Electroanatomic left ventricular mapping in the porcine model of healed anterior myocardial infarction. Correlation with intracardiac echocardiography and pathological analysis.

BACKGROUND: Catheter ablation for ventricular tachycardia in healed infarction is limited to patients with inducible, tolerated arrhythmias. Strategies that would allow mapping during sinus rhythm might obviate this limitation. METHODS AND RESULTS: Two sets of experiments were performed in adult pigs to refine a new technique for left ventricular mapping. First, detailed endocardial maps were done in 5 normal pigs and 7 pigs 6 to 10 weeks after left anterior descending coronary artery infarction to characterize electrograms in normal and infarcted tissue by electroanatomic mapping (CARTO, Biosense). Electrogram recording sites were verified by intracardiac echo (ICE, 9 MHz) and grouped by location: infarct (area of akinesis by ICE), border (0.5-cm perimeter of akinetic area), and remote. Compared with remote sites, electrograms from infarct sites had smaller amplitudes (1.2+/-0.5 versus 5.1+/-2.1 mV, P<0.001), longer durations (74.2+/-26.3 versus 36.3+/-6.4 ms, P<0.001), and more frequent notched or late components. Border zone electrograms were intermediate in amplitude and duration. Second, infarct characterization by electroanatomic mapping was compared with pathological (exclusion of triphenyltetrazolium chloride staining) and ICE measurements. Infarct size by pathology correlated with the area defined by contiguous electrograms with amplitude

Exercise systolic blood pressure: a powerful determinant of increased left ventricular mass in patients with hypertension.

This study examines the relation between left ventricular mass determined by two-dimensional echocardiography and exercise blood pressure in patients with hypertension. Sixty-seven patients with hypertension and 19 normal subjects underwent treadmill exercise testing and two-dimensional echocardiography. The left ventricular mass index in the normal subjects was 80 +/- 10 g/m2 (mean +/- SD). Patients with hypertension were classified into two groups according to left ventricular mass: Group I (n = 42) had normal mass and Group II (n = 25) had increased mass (greater than 2 SD above the mean value in 19 normal subjects). There was a poor correlation between left ventricular mass and blood pressure at rest. However, a better correlation was found between left ventricular mass and exercise systolic blood pressure (r = 0.58, p less than 0.001) or the change in systolic blood pressure from rest to exercise (r = 0.48, p less than 0.001). Twenty-two (76%) of 29 patients with an exercise systolic blood pressure of 190 mm Hg or greater had an increased left ventricular mass index, whereas only 3 (8%) of 38 patients with an exercise systolic blood pressure of less than 190 mm Hg had an increased left ventricular mass index (p less than 0.0001). Thus, in patients with hypertension, left ventricular mass index is poorly related to blood pressure at rest, but is related to exercise systolic blood pressure. Patients with an exercise systolic blood pressure of 190 mm Hg or greater usually have an increased left ventricular mass. These findings may have therapeutic implications.

Narrowing of the superior vena cava-right atrium junction during radiofrequency catheter ablation for inappropriate sinus tachycardia: analysis with intracardiac echocardiography.

OBJECTIVES: The study explored the potential for tissue swelling and venous occlusion during radiofrequency (RF) catheter ablation procedures using intracardiac echocardiography (ICE). BACKGROUND: Transient superior vena cava occlusion has been reported following catheter ablation procedures for inappropriate sinus tachycardia (IST). Presumably, venous occlusion could occur owing to thrombus formation or tissue swelling with resultant narrowing of the superior vena cava-right atrial (SVC-RA) junction. METHODS: Intracardiac echocardiography (9 MHz) was used to guide ablation catheter position and for continuous monitoring during RF application in 13 ablation procedures in 10 patients with IST. The SVC-RA junction was measured prior to and following ablation. Successful ablation was marked by abrupt reduction in the sinus rate and a change to a superiorly directed p-wave axis. RESULTS: Eleven of 13 procedures were successful, requiring 29 +/- 20 RF lesions. Prior to the delivery of RF lesions, the SVC-RA junction measured 16.4 +/- 2.9 mm. With RF delivery, local and circumferential swelling was observed, causing progressive reduction in the diameter of the SVC-RA junction to 12.6 +/- 3.3 mm (24% reduction, p = 0.0001). A reduction in SVC-RA orifice diameter of > or = 30% compared to baseline was observed in five patients. CONCLUSIONS: The delivery of multiple RF ablation lesions, often necessary for cure of IST, can cause considerable atrial swelling and resultant narrowing of the SVC-RA junction. Smaller venous structures, such as the coronary sinus and the pulmonary veins, would also be expected to be vulnerable to this complication. Thus, ICE imaging may be helpful in preventing excessive tissue swelling leading to venous occlusion during catheter ablation procedures.

Two-dimensional echocardiographic estimation of right ventricular ejection fraction in patients with coronary artery disease.

Two-dimensional echocardiographic determination of right ventricular ejection fraction was compared with right ventricular ejection fraction obtained by first pass radionuclide angiography in 39 patients with coronary artery disease. Apical four chamber and two chamber right ventricular views were obtained in 34 (87%) of the 39 patients, while a subcostal four chamber view was obtained in 31 patients (80%). Right ventricular ejection fraction by two-dimensional echocardiography was calculated by the biplane area-length and Simpson's rule methods using two paired orthogonal views and utilizing a computerized light-pen method for tracing the right ventricular endocardium. A good correlation (r = 0.74 to 0.78) was found between radionuclide angiographic and two-dimensional echocardiographic right ventricular ejection fraction for each method used. Patients with acute inferior myocardial infarction had the lowest right ventricular ejection fraction by radionuclide angiography and two-dimensional echocardiography (p less than 0.05 compared with patients with right coronary artery obstruction and no infarction). There were no differences in right ventricular ejection fraction between patients with acute and old inferior myocardial infarction by both techniques. No correlation was found between left and right ventricular ejection fraction by radionuclide angiography (r = 0.16). It is concluded that 1) right ventricular ejection fraction by two-dimensional echocardiography correlates well with radionuclide angiographic measurements and can reliably evaluate right ventricular function in coronary artery disease, 2) patients with inferior myocardial infarction have reduced right ventricular ejection fraction, and 3) changes in left ventricular ejection fraction do not directly influence right ventricular function.

Myocardial oxygen supply/demand ratio in aortic stenosis: hemodynamic and echocardiographic evaluation of patients with and without angina pectoris.

Angina pectoris is a common symptom in patients with aortic stenosis without coronary artery disease. To investigate the correlates of angina pectoris, echocardiographic and hemodynamic data from 44 patients with aortic stenosis and no coronary artery disease (mean age 56 +/- 10 years) were analyzed. Twenty-three patients had no angina pectoris and 21 patients had angina pectoris. The ratio of the diastolic pressure-time index (area between the aortic and left ventricular pressure curves during diastole) to the systolic pressure-time index (area under the left ventricular pressure curve during systole), an index of the oxygen supply/demand ratio, was not different in patients with or without angina pectoris. There were no differences between patients with and without angina pectoris in echocardiographically determined wall thickness, chamber size, systolic and diastolic wall stress and left ventricular mass; in electrocardiographically defined voltage; and in hemodynamically defined aortic valve area, transaortic gradient and stroke work index. Thus, echocardiographic and hemodynamic measurements at rest are not significantly different in the presence or absence of angina pectoris in patients with aortic stenosis. Dynamic data appear to be essential for evaluation of the mechanisms of angina pectoris in patients with aortic stenosis.

Development and regression of left ventricular hypertrophy.

Left ventricular hypertrophy is an important adaptive response to chronic pressure or volume overload of the left ventricle. The different types and the pathophysiologic mechanisms of the development of left ventricular hypertrophy in various disease states are reviewed. Detection of left ventricular hypertrophy may be accomplished by electrocardiography and cardiac angiography. Echocardiography, however, is the most accurate noninvasive method to detect the presence and estimate the severity of increased left ventricular mass. The clinical significance of left ventricular hypertrophy and its prognostic implications in several cardiac diseases associated with hypertrophy are discussed. The critical transition stage from adaptive, compensatory and reversible left ventricular hypertrophy to "pathologic" hypertrophy with impaired left ventricular contractility and irreversible myocardial damage is yet unknown. Recent data are presented that provide evidence of regression of left ventricular hypertrophy after medical treatment of patients with hypertension and after aortic valve replacement in patients with aortic valve disease. The clinical importance of regression of hypertrophy and its effects on long-term prognosis remain to be determined.

Cardiac function in patients with cystic fibrosis: evaluation by two-dimensional and Doppler echocardiography.

Two-dimensional and Doppler echocardiography were performed in 17 consecutive hospitalized patients with cystic fibrosis aged 6 to 38 years (mean 21 +/- 9) and in 10 normal subjects aged 24 +/- 7 years. Left ventricular and right ventricular ejection fraction were measured by a computerized light pen system and Simpson's rule from two-dimensional echocardiographic apical four and two chamber views. Right ventricular wall thickness, inferior vena cava size and the presence of tricuspid regurgitation by Doppler recording were also assessed. National Institutes of Health (NIH) score of clinical severity ranged from 22 to 72 (mean 51 +/- 15) (100 = excellent, 0 = poor). Four patients, all with an NIH score of 40 or less, died of respiratory failure within 1 year of the echocardiographic study. There was no significant difference between patients with cystic fibrosis and normal subjects with regard to right ventricular ejection fraction (59 +/- 11 versus 61 +/- 10%), left ventricular ejection fraction (67 +/- 8 versus 70 +/- 8%) and right ventricular systolic (5 +/- 1 versus 5 +/- 0.5 mm) and diastolic (2.4 +/- 0.5 versus 2.5 +/- 0.5 mm) wall thicknesses. A dilated inferior vena cava and mild tricuspid regurgitation by Doppler recording were detected in only one patient. A poor correlation was found between right ventricular ejection fraction and NIH clinical score (r = 0.26), chest X-ray score (r = 0.29) and pulmonary function tests. It is concluded that right and left ventricular systolic function is preserved in patients with moderately severe cystic fibrosis; clinical status in these patients is probably determined by the pulmonary rather than cardiac involvement.

Transthoracic high frequency (7.5 MHz) echocardiographic assessment of coronary vascular reserve and its relation to left ventricular mass.

Transthoracic high frequency (7.5 MHz) ultrasonography can visualize the distal left anterior descending coronary artery. Thirty-seven patients were studied before and after administration of 0.4 mg sublingual nitroglycerin to determine whether this technique could quantitatively record changes in coronary artery diameter after intervention. Left anterior descending coronary artery diameter increased from 2.2 to 2.8 mm (p less than 0.05). The vasodilator response of this artery was compared with left ventricular mass index in normal subjects, patients with congestive cardiomyopathy and those with end-stage renal disease and left ventricular hypertrophy. Left anterior descending artery diameter increased 55% in normal subjects, 27% in patients with dilated cardiomyopathy and 10% in those with end-stage renal disease with left ventricular hypertrophy. These results demonstrate that high frequency ultrasound can detect nitroglycerin-induced changes in left anterior descending artery diameter. The percent increase is related to the diameter before nitroglycerin administration, which is related to the underlying diagnosis and left ventricular mass index.

Clinical and echocardiographic evaluation of the St. Jude cardiac valve prosthesis: follow-up of 126 patients.

One hundred twenty-six patients with a St. Jude valve prosthesis were followed up clinically and studied by combined M-mode echocardiography and phonocardiography. Fifty patients underwent aortic valve replacement, 58 underwent mitral valve replacement and 18 underwent a combination of the two. The early postoperative mortality rate was 8% for aortic, 6.9% for mitral and 6% for combined valve replacement. Follow-up ranged from 2 to 46 months (mean +/- SD 28 +/- 9). The late postoperative mortality rate was 5%; in patients who survived, improvement in New York Heart Association functional class occurred in 97%. Major thromboembolic events occurred in two patients and anticoagulation-related complications occurred in three patients. Valve-related complications occurred in 14 patients and included bacterial endocarditis (6 patients), paravalvular leak (5 patients), severe hemolysis (1 patient), thrombosis of valve (1 patient) and possible mechanical valve failure (1 patient). In 7 of these 14 patients, repeat surgery was required and 5 patients survived. Abnormal echocardiographic findings in these seven patients included a shortened aortic closure (A2) to mitral valve opening interval, increased left atrial and left ventricular size and initial diastolic rounding of the St. Jude valve motion in the patient with the thrombosed valve. It is concluded that the St. Jude valve prosthesis is associated with favorable functional results and a low complication rate for a mean follow-up period of 28 months. Combined M-mode echocardiography and phonocardiography may be useful in assessing patients with suspected complications related to the St. Jude cardiac valve.

Correlation among right ventricular preload, afterload and ejection fraction in mitral valve disease: radionuclide, echocardiographic and hemodynamic evaluation.

The relation among right ventricular preload, afterload and ejection fraction in patients with mitral valve disease has not been well elucidated. In this study, measurements were made of intracardiac pressures and forward cardiac output during cardiac catheterization (n = 43), the ejection fraction by radionuclide angiography (n = 43) and end-systolic radius and wall thickness by M-mode echocardiography (n = 22). There was a linear correlation between pulmonary artery pressure and right atrial pressure (r = 0.57, p less than 0.01). The right ventricular peak circumferential systolic wall stress was increased in 68% of the patients (in comparison with wall stress measurements obtained in 10 normal subjects). The right ventricular ejection fraction was abnormal in 38 patients (88%) and abnormal in 14 of the 15 patients with high wall stress. There was an inverse correlation between ejection fraction and end-diastolic volume (r = -0.61, p less than 0.001). The right ventricular ejection fraction measurement was repeated within 3 months after mitral valve replacement in 16 patients; the ejection fraction increased from 21 +/- 9 to 29 +/- 10% (mean +/- standard deviation) after surgery (p less than 0.01), but normalization of the ejection fraction was observed in only 3 patients (19%). Thus, abnormal right ventricular ejection fraction, which is observed in most patients with rheumatic mitral valve disease, results from inappropriate wall stress or depressed inotropic response of the right ventricle due to damage. Right ventricular dilation appears to be a compensatory mechanism to maintain the cardiac output.

Two-dimensional echocardiographic determination of left atrial emptying volume: a noninvasive index in quantifying the degree of nonrheumatic mitral regurgitation.

Several noninvasive techniques, including radionuclide angiography and Doppler echocardiography, have attempted to measure the regurgitant volume in patients with mitral regurgitation; however, none of these techniques are entirely satisfactory. Utilizing a computerized light pen method for tracing the left atrial endocardial border during systole and diastole in two orthogonal planes (apical four and two chamber views), biplane volume determinations were calculated in 12 normal subjects and 30 patients with nonrheumatic mitral regurgitation. Left atrial emptying volume determinations were performed by subtracting the left atrial end-diastolic volume from the left atrial end-systolic volume. The degree of mitral regurgitation was visually assessed as normal (0, trivial, Group I, 12 patients), mild (1+, Group II, 4 patients), moderate (2+, Group III, 8 patients), moderately severe (3+, Group IV, 12 patients) and severe (4+, Group V, 6 patients) by contrast left ventricular angiography and also quantitatively by regurgitant fraction at cardiac catheterization. All 18 patients with moderately severe (Group IV) and severe (Group V) mitral regurgitation had a left atrial emptying volume greater than 40 ml compared with none of the normal subjects and patients with mild (Group II) or moderate (Group III) mitral regurgitation. There was good correlation between left atrial emptying volume and mitral regurgitant fraction (r = 0.85, p less than 0.01). Thus, in patients with nonrheumatic mitral regurgitation, left atrial emptying volume is useful in separating mild from severe mitral regurgitation.

Anuloaortic ectasia: a clinical and echocardiographic study.

Twenty-six patients with an aortic root diameter greater than or equal to 3.7 cm by 2-dimensional echocardiography (2-D echo) were studied. Group I consisted of 14 patients (mean age 50 +/- 14 years) with idiopathic anuloaortic ectasia and group II consisted of 12 patients (mean age 60 +/- 12 years) with secondary causes of aortic root dilatation. Patients in group I had a significantly larger aortic root diameter at the level of the aortic valve (5.0 +/- 0.7 cm) and 2 cm above the aortic valve (5.3 +/- 1.2 cm) as assessed by echo than did patients in group II (4.1 +/- 0.3 and 4.4 +/- 0.4 cm, respectively, p less than 0.025). The diameter of descending thoracic aorta was slightly larger in patients in group II (3.1 +/- 0.8 vs 2.7 +/- 0.5 cm, difference not significant). Over a mean follow-up period of 18 months, in group I, aortic dissection developed in 3 patients and severe aortic regurgitation and congestive heart failure in 2; 7 patients had aortic root grafting, aortic valve replacement or both. The 3 patients in group I with aortic dissection had an aortic root diameter greater than or equal to 5.3 cm, but 4 asymptomatic patients also had a diameter greater than 5 cm. Only 1 patient in group II required surgery for aortic dissection. Thus, 2-D echo is useful in identifying and following high-risk patients with anuloaortic ectasia.

Effect of depressed left ventricular function on hemodynamics of normal St. Jude Medical prosthesis in the aortic valve position.

To evaluate the effect of left ventricular (LV) dysfunction on Doppler-derived transprosthetic hemodynamic indexes in patients with normally functioning St. Jude aortic valve prostheses, 74 consecutive patients were studied. LV ejection fraction was assessed by using Simpson's biplane rule. The 34 patients with normal ejection fraction (greater than or equal to 0.51) (group A) generally had the highest values of peak (31 +/- 13 mm Hg) and mean (16 +/- 6 mm Hg) gradients, whereas 19 patients with moderate to severe reduction of ejection fraction (less than or equal to 0.31) (group C) had the lowest values (17 +/- 6 and 9 +/- 3 mm Hg, respectively) (p less than 0.05). Significant decreases (p less than 0.05) for acceleration and corrected (for heart rate) velocity time integral in group C were noted compared to group A, and group B (21 patients with mild to moderately reduced ejection fraction [0.50 to 0.32]). A significant inverse correlation for Doppler-derived peak and mean gradients and corrected velocity time integral was demonstrated with increasing aortic valve prosthetic sizes from 19 to 29 mm in group A patients (r = -0.41 to -0.71) but less so in group B or C. Thus, in addition to valve size, LV function should be considered an important factor in detecting prosthetic valvular flow characteristics and dysfunction. A normal derived velocity and gradient in patients with moderately to severely depressed LV function may not rule out significant valvular stenosis.

Two-dimensional echocardiographic determination of right atrial emptying volume: a noninvasive index in quantifying the degree of tricuspid regurgitation.

Contrast echocardiography and inferior vena cava ultrasonography are useful techniques in diagnosing tricuspid regurgitation (TR) but are not helpful in estimating the severity. Using a computerized light-pen method for tracing the right atrial (RA) border during systole and diastole in the apical 4-chamber view, single-plane volume determinations were calculated in 10 normal subjects (Group I), 18 patients with atrial fibrillation (AF) and no TR (Group II), 14 patients with mitral stenosis and mild TR (Group IIIa), and 8 patients with mitral stenosis and severe TR (Group IIIb). TR was quantitated as absent, mild or severe by contrast right ventriculography. The RA end-systolic volume was 36.4 +/- 13.1 ml in Group I patients, 59.1 +/- 16.8 ml in Group II patients, 76.9 +/- 55.4 ml in Group IIIa patients, and 154.6 +/- 57.3 ml in Group IIIb patients (all Groups versus Group I, p less than 0.001). The mean RA emptying volume, which equals RA end-systolic volume--RA end-diastolic volume, was 15.3 +/- 5.0 for Group I, 17.7 +/- 3.0 for Group II, 30.4 +/- 8.0 for Group IIIa, and 71.6 +/- 25.4 for Group IIIb. All 8 patients with severe TR but none of the 14 patients with mild TR had an RA emptying volume greater than 40 ml (p less than 0.001). In addition, all 28 patients in Groups I and II but only 4 of 14 patients in Group III had an RA emptying volume less than 26 ml (p less than 0.01). The mean RA pressure measured at cardiac catheterization correlated with RA emptying volume (r = 0.71, p less than 0.001). Thus, RA emptying volume is useful for separating severe TR from mild TR in patients with mitral stenosis.