Leaflet Tips Research Articles

Simultaneous Determination of Aortic Valve Area by the Gorlin Formula and by Transesophageal Echocardiography Under Different Transvalvular Flow Conditions: Evidence That Anatomic Aortic Valve Area Does Not Change With Variations in Flow in Aortic Stenosis

Objectives. The purpose of this study was to determine the impact of changes in flow on aortic valve area (AVA) as measured by the Gorlin formula and transesophageal echocardiographic (TEE) planimetry.Background. The meaning of flow-related changes in AVA calculations using the Gorlin formula in patients with aortic stenosis remains controversial. It has been suggested that flow dependence of the calculated area could be due to a true widening of the orifice as flow increases or to a disproportionate flow dependence of the formula itself. Alternatively, anatomic AVA can be measured by direct planimetry of the valve orifice with TEE.Methods. Simultaneous measurement of the planimetered and Gorlin valve area was performed intraoperatively under different hemodynamic conditions in 11 patients. Left ventricular and ascending aortic pressures were measured simultaneously after transventricular and aortic punctures. Changes in flow were induced by dobutamine infusion. Using multiplane TEE, AVA was planimetered at the level of the leaflet tips in the short-axis view.Results. Overall, cardiac output, stroke volume and transvalvular volume flow rate ranged from 2.5 to 7.3 liters/min, from 43 to 86 ml and from 102 to 306 ml/min, respectively. During dobutamine infusion, cardiac output increased by 42% and mean aortic valve gradient by 54%. When minimal flow was compared with maximal flow, the Gorlin area varied from (mean ± SD) 0.44 ± 0.12 to 0.60 ± 0.14 cm2(p < 0.005). The mean change in Gorlin area under different flow rates was 36 ± 32%. Despite these changes, there was no significant change in the planimetered area when minimal flow was compared with maximal flow. The mean difference in planimetered area under different flow rates was 0.002 ± 0.01 cm2(p = 0.86).Conclusions. By simultaneous determination of Gorlin formula and TEE planimetry valve areas, we showed that acute changes in transvalvular volume flow substantially altered valve area calculated by the Gorlin formula but did not result in significant alterations of the anatomic valve area in aortic stenosis. These results suggest that the flow-related variation in the Gorlin AVA is due to a disproportionate flow dependence of the formula itself and not a true change in valve area.(J Am Coll Cardiol 1997;29:1296–302)

Automatic Border Dectection in the Evaluation of Diastolic Function in Normal Neonates 129

Automatic border detection (ABD) is an alternative method to Doppler echocardiography (DE) for assessment of LV diastolic function. To date, no information is available regarding the utility of ABD to assess diastolic function among normal neonates. Methods: To compare ABD to standard DE parameters and to assess the reproducibility of ABD among observers, we studied 17 normal full-term neonates (mean birth wt 3.5±0.3 kg) at birth (17.4±3.9 hr) and again at 14.8±2.2 days of life to evaluate LV diastolic function by both methods. DE parameters obtained at the mitral leaflet tips were: Peak E-and A-wave velocity; E/A ratio; E, A, and total time velocity integrals (TVI); deceleration time. Rapid and atrial filling fractions were derived from the TVIs. Isovolumic relaxation time was measured. ABD parameters including rapid filling fraction (RFF) area change, atrial filling fraction (AFF) area change, ratio RFF/AFF, peak rapid and atrial filling rates and their ratio were obtained in the short-axis view after proper gain and region of interest were set. An average of 5 cardiac cycles was used for each measurement. Results: No significant change was observed in any ABD or DE parameter between birth and later studies. Interobserver variability for individual ABD measurements ranged from 0-11%. In comparison to DE, the RFF was greater and the AFF was less by ABD. Regression analysis showed only weak correlation between each measure by the 2 methods. However, the relationship between RFF and AFF obtained by each method was constant across the studies. Similarly, weak correlations were observed when peak E velocity by DE and peak rapid filling rate by ABD and peak A velocity by DE and peak atrial filling rate by ABD were compared.Conclusions: (1) Similar to traditional DE parameters, the ABD method showed that no significant change in LV diastolic function occurred in the first 2 weeks of life. (2) Weak correlation between ABD and DE parameters of filling was observed which may relate to technical differences between methods. (3) ABD was a reproducible and reliable method to assess LV diastolic function in neonates.

Accurate assessment of mitral valve area in patients with mitral stenosis by three-dimensional echocardiography

The accuracy of measurements of mitral valve orifice area (MVA) from three-dimensional echocardiographic (3DE) image data sets obtained by a transthoracic or transesophageal rotational imaging probe was studied in 15 patients with native mitral stenosis. The smallest MVA was identified from a set of eight parallel short-axis cut planes of the mitral valve between the anulus and the tips of leaflets (paraplane echocardiography) and measured by planimetry. In addition, MVA was measured from the two-dimensional short-axis view (2DE). Values of MVA measured by 3DE and 2DE were compared with those calculated from Doppler pressure half-time (PHT) as a gold standard. Observer variabilities were studied for 3DE. MVA measured from PHT ranged between 0.55 and 3.19 cm 2 (mean ± SD 1.57 ± 0.73 cm 2), from 3DE between 0.83 and 3.23 cm 2 (mean ± SD 1.55 ± 0.67 cm 2), and from 2DE between 1.27 and 4.08 cm 2 (mean ± SD 1.9 ± 0.7 cm 2). The variability of intraobserver and interobserver measurements for 3DE measurements was not significantly different ( p = 0.79 and p = 0.68, respectively); for interobserver variability, standard error of the estimate = 0.25. There was excellent correlation, close limits of agreement (mean difference ± 2 SD), and nonsignificant differences between 3DE and PHT for MVA measurements ( r = 0.98 [0.02 ± 0.3] and p = 0.6), respectively. There was moderate correlation, wider limits of agreement, and significant difference between 2DE and PHT for MVA measurements ( r = 0.89 [0.32 ± 0.66] and p = 0.002), respectively. This may be related to the difficulties in visualization of the smallest orifice in precordial short-axis views. This study suggests that three-dimensional image data sets, by providing the possibility of “computer slicing” to generate equidistant parallel cross sections of the mitral valve independently from physically dictated ultrasonic windows, allow accurate and reproducible measurement of the MVA. (J Am Soc Echocardiogr 1997;10:133-40.)

Dobutamine stress Doppler echocardiography: reproducibility and physiologic left ventricular filling patterns

Qualitatively, dobutamine stress echocardiography has become an established procedure. Quantitative results are in great demand but this is still difficult due to limited endo- and epicardial border definition. Transmitral Doppler variables are strictly quantitative and less subjective. Furthermore, ischemic alterations precede systolic ones (ischemic cascade). There are preliminary reports of the utility of dobutamine stress Doppler echocardiography, but proof of reproducibility and left ventricular filling patterns are still lacking. Fourteen healthy volunteers (10 men, 4 women, median age 25.9 years, range 21–32 years) were investigated according to the usual dobutamine stress echocardiographic protocol (5, 10, 15, 20, 30, 40 and 40 μg/kg/min+0.5 mg atropine). At each titration step a standardized transmitral PW-Doppler recording with the sample volume positioned at the opened mitral leaflet tips was analyzed three times by two independent, experienced investigators. Of the early, late, and mean velocities ( V maxE, V maxA, V mean), time integrals (VTI-E, VTI-A, VTI), their ratios (E/A, E/A VTI), and various time intervals ( T acc, T dec, E- and A-duration, FillT), V maxE (0.82 to 1.09 m/s; P<0.0001), VTI-E (16.17 to 17.19 cm; P<0.0001) and V mean (0.29 to 0.82 m/s; P<0.0001) were found to have the greatest discriminatory power, commencing already at a dose of 10–15 μg/kg/min dobutamine. V maxE and VTI-E demonstrated the smallest intra- and interobserver variation without any increase in variability during incremental dose titration. Assessment of the early diastolic filling pattern by Doppler echocardiography is a valuable quantitative and reproducible adjunct to conventional dobutamine stress echocardiography. Further controlled studies in coronary artery disease patients have to confirm, whether lower dobutamine doses could be used in the test and sensitivity increased due to better data acquisition in cases of limited echogenicity, less subjectivity, and earlier onset of ischemic alterations.

Pulmonary venous flow velocity patterns in 143 normal subjects aged 20 to 80 years old. An echo 2D colour Doppler cooperative study.

In order to find out the normal values and to evaluate the effects of age, heart rate, sex, and haemodynamic and standard echocardiographic parameters on pulmonary venous flow velocity obtained by the transthoracic approach. Doppler pulmonary venous flow parameters were measured in 143 healthy subjects aged from 20 to 80 years. Doppler pulmonary venous flow parameters which had the best correlation with age were: the peak velocity of the systolic wave (r = 0.39) and its integral (r = 0.5), the peak velocity of the diastolic wave (r = -0.6) and its integral (r = -0.44); the systolic (r = 0.68) and diastolic fractions (r = -0.68); the systolic/diastolic peak velocity ratio (r = 0.73) and the systolic/diastolic integral ratio (r = 0.7). The atrial reversal wave did not correlate with age; the atrial reversal wave was more difficult and probably less reliable to measure than the systolic and diastolic waves. The correlations of pulmonary venous flow parameters with mitral flow parameters were also examined. This study showed that, in healthy subjects, despite an increase in the early and atrial waves from the annulus to the tips of the mitral leaflets, there is a similar association between pulmonary venous flow and mitral flow measured at the annulus or at the tips of the mitral leaflets. The intra-observer reproducibility of all the pulmonary venous flow parameters considered were found to be excellent. Moderate inter-observer variability was observed for the systolic, diastolic and atrial reversal wave peak velocities and integrals; however, the systolic/diastolic ratio improved the precision of the measurements. Multivariate analysis showed that age is the principal determinant of the Doppler parameters of pulmonary venous flow: heart rate, sex, body surface area, the size of the left atrium in systole and the left ventricular ejection fraction all influence the Doppler parameters of pulmonary venous flow, even if only slightly.

Transient pressure signals in mechanical heart valve cavitation.

The purpose of this investigation was to establish a correlation between mechanical heart valve (MHV) cavitation and transient pressure (TP) signals at MHV closure. This correlation may suggest a possible method to detect in vivo MHV cavitation. In a pulsatile mock flow loop, a study was performed to measure TP and observe cavitation bubble inception at MHV closure under simulated physiologic ventricular and aortic pressures at heart rates of 70, 90, 120, and 140 beats/min with corresponding cardiac outputs of 5.0, 6.0, 7.5, and 8.5 L/min, respectively. The experimental study included two bileaflet MHV prostheses: 1) St. Jude Medical 31 mm and 2) Carbomedics 31 mm. High fidelity piezo-electric pressure transducers were used to measure TP immediately before and after the valve leaflet/housing impact. A stroboscopic lighting imaging technique was developed to capture cavitation bubbles on the MHV inflow surfaces at selected time delays ranging from 25 microseconds to 1 ms after the leaflet/housing impact. The TP traces measured 10 mm away from the valve leaflet tip showed a large pressure reduction peak at the leaflet/housing impact, and subsequent high frequency pressure oscillations (HPOs) while the cavitation bubbles were observed. The occurrence of cavitation bubbles and HPO bursts were found to be random on a beat by beat basis. However, the amplitude of the TP reduction, the intensity of the cavitation bubble (size and number), and the intensity of HPO were found to increase with the test heart rate. A correlation between the MHV cavitation bubbles and the HPO burst was positively established. Power spectrum analysis of the TP signals further showed that the frequency of the HPO (cavitation bubble collapse pressures) ranged from 100 to 450 kHz.

Echocardiographic evaluation of patients with acute rheumatic fever and rheumatic carditis.

Cardiac involvement is the most important component of acute rheumatic fever. The role of echocardiography in the evaluation of rheumatic carditis has not been adequately defined. We used echocardiography in a large sample of patients with acute rheumatic fever to describe morphological abnormalities associated with rheumatic carditis and to assess its role in the diagnosis of rheumatic carditis. Cross-sectional and color Doppler echocardiographic examination was performed in 108 consecutive patients with acute rheumatic fever within 24 to 48 hours of diagnosis. Twenty-eight patients had acute rheumatic fever without clinical evidence of carditis (group 1). Thirty-five patients had a presumed first episode of rheumatic carditis (group 2), and 45 patients had a recurrence of carditis (group 3). Patients in group 1 did not demonstrate any evidence of valvular regurgitation. Mitral regurgitation was the most common Doppler echocardiographic feature in groups 2 (94%) and 3 (84%). Valvular thickening with or without restriction of leaflet mobility was frequently seen in rheumatic carditis. One of every 4 patients with rheumatic carditis demonstrated echocardiographic presence of focal valvular nodules. These nodules were found on the body and the tips of the mitral valve leaflets and disappeared on follow-up. Ventricular dilatation (group 2, 54%; group 3, 74%) and restriction of leaflet mobility (group 3, 37%) were common mechanisms of mitral regurgitation in rheumatic carditis; valve prolapse (group 2, 9%; group 3, 16%) and annular dilatation (group 2, 12%; group 3, 21%) were infrequent. The majority of patients with rheumatic carditis had normal left ventricular systolic function. Congestive heart failure (group 2, 17%; group 3, 40%) was invariably associated with the presence of hemodynamically significant valve lesions. On follow-up, no patient in group 1 developed valvular regurgitation. In group 2 patients, a progressive decrease in left ventricular dimensions was observed without any change in ventricular fractional shortening. Valvular regurgitation remained unchanged in 69% of patients, decreased in 22%, and disappeared in 9%. In patients with rheumatic carditis, the mitral valve is most often involved and mitral regurgitation is the most common finding on color flow imaging. Mitral regurgitation in rheumatic carditis is related to ventricular dilatation and/or restriction of leaflet mobility. Rheumatic carditis does not result in congestive heart failure in the absence of hemodynamically significant valve lesions. In a quarter of patients with rheumatic carditis, we observed valve nodules that may represent echocardiographic equivalents of rheumatic verrucae. Our study failed to reveal any incremental diagnostic utility of echocardiography and Doppler color flow imaging in rheumatic fever without clinical evidence of carditis.

Left ventricular blood flow patterns in normal subjects: A quantitative analysis by three-dimensional magnetic resonance velocity mapping

Magnetic resonance velocity mapping was used to investigate the hypothesis of a vortex motion within the left ventricle interacting with mitral valve motion and inflow velocity. In vitro flow visualization studies have suggested the presence of a large anterior vortex inside the left ventricle during mitral inflow. However, to our knowledge the occurrence of this phenomenon has not been demonstrated in the human left ventricle. Magnetic resonance velocity mapping was performed in 26 healthy volunteers using a flow-adjusted gradient sequence for three-dimensional flow velocity acquisition in the long-axis plane of the left ventricle. By computer processing, the flow vectors in the left ventricle were visualized and animated dynamically. The early diastolic mitral inflow was apically directed, and a large counterclockwise anterior vortex was created within the left ventricle shortly after the onset of the mid-diastolic semiclosure of the anterior mitral leaflet. During mid-diastolic diastasis, mitral inflow ceased until the flow accelerated again at atrial systole. The final closure of the mitral valve was preceded by a smaller vortex seen at the tips of the mitral leaflets. At systolic ejection, all flow vectors were directed toward the left ventricular outflow tract. The anterior vortex had a radius of 1.62 +/- 0.24 cm (mean +/- SD), and the average angular velocity (i.e., the rotation of an element about the center of the vortex within the central core) was 30.08 +/- 9.98 radians/s. The maximal kinetic energy of the anterior vortex was 4.3 x 10(-4) +/- 7.1 x 10(-5) J. The hypothesis of a diastolic vortex formation in the human left ventricle was confirmed, and its close temporal relation to the motion of the anterior mitral leaflet was demonstrated.

980-89 Lack of Evidence for Atrial Stunning After DC Shock in Patients in Normal Sinus Rhythm Undergoing ICD Insertion: A Study Using TEE

Transient left atrial (LA) dysfunction (“stunning”) and the appearance of spontaneous echo contrast (“smoke”) have been reported in patients undergoing DC cardioversion of atrial fibrillation. It has been suggested that cardioversion-induced LA dysfunction may promote new thrombus formation leading to thromboembolic complications in AF patients even in the absence of demonstrable LA thrombus prior to cardioversion. In order to confirm previous observations of LA stunning end to investigate the determina nts of this response, we investigated LA function in a series of patients undergoing implantable defibrillator insertion and testing. Eight patients (67 ± 6 yrs, 5 M/3 F) with ischemic heart disease (n = 6) or cardiomyopathy (n = 2) and VTNF were studied. All patients were in NSR, had significant impairment of systolic LV function, and demonstrated inducible VT or VF in the EP lab. Intraoperative transesophegeal echocardiography with a biplane or multiplane probe was used to image the LA, mitral valve and LA appendage (LAA). Blood flow velocities were measured at the tips of the MV leaflets and LAA orifice by pulsed-wave Doppler before and 30 to 120 seconds after DC shocks of 15–20 joules with transvenous intracardiac electrodes lin SVC and RV apex, n = 7) or epicardial patches (n = 1) while in sinus rhythm. Measurements from three different cardiac cycles were averaged for each patient. Baseline LAA orifice flow velocity was 44 ± 16 cm/s and remained unchanged after DC shock, 46 ± 20 cm/s (p = ns). Similarly, MV peak A-wave velocity was 70 ± 34 cm/s at baseline and was not significantly different after DC shock, 69 ± 42 cm/s (p = ns). No evidence of LA “smoke” was seen in any patient before or after the shock. As opposed to previous reports after cardioversion of atrial fibrillation, DC shocks alone do not produce LA dysfunction in patients in NSR even in the presence of left venticular dysfunction. LA stunning after DC shocks may require prior atrial fibrillation or specific atrial substrate.

Response of six patients with idiopathic hypereosinophilic syndrome to interferon alfa*

Response of six patients with idiopathic hypereosinophilic syndrome to interferon alfa*

Three-dimensional transesophageal echocardiography in the diagnosis of mitral valve prolapse

Because the anulus of the mitral valve is nonplanar in systole, false-positive diagnosis of mitral valve prolapse may result from two-dimensional transthoracic echocardiography. Because of the superior image quality of TEE, we used the three-dimensional TEE technique to evaluate the mitral valve in both normal subjects and patients with mitral valve prolapse and with ruptured chordae tendineae. After a conventional TEE examination, sequential images of longitudinal views were obtained by probe rotation. The images at 5-degree intervals were stored in machine cine memory loop; the special temporal images were selected with ECG gating and videorecorded. During the examination, 6 to 8 images of the left heart were recorded for later off-line, three-dimensional reconstruction. A total of 42 subjects were studied: 32 normal, 9 with mitral valve prolapse, and 1 with ruptured chordae tendineae. In normal subjects, three-dimensional TEE showed nonplanarity of the entire mitral valve, which assumes a saddle shape. In mitral valve prolapse, either the anterior or posterior leaflet protruded into the left atrium like a spoon; when both leaflets are involved, they prolapse like two spoons. The anterior and posterior leaflets coapted poorly, and there was a seam between them. In ruptured chordae tendineae the tip of the mitral leaflet protruded during systole into the left atrium far from the coaptation point and was perpendicular to the body of the mitral valve and parallel to the anterior and posterior walls of the left atrium. Three-dimensional TEE study gives a clear stereoscopic view of the mitral valve and provides accurate anatomic data for the mitral valve apparatus in both normal subjects and patients with mitral valve prolapse and with ruptured chordae tendineae. It helps define spatial location and extent of the vulvular deformities. Thus three-dimensional imaging in TEE provides a new perspective that will refine the diagnosis of mitral valve prolapse.

Two-dimensional mitral flow velocity profiles in pig models using epicardial doppler echocardiography

Objectives. This study investigated the velocity distribution across the natural mitral valve.Background. Information about the blood velocity distribution across the mitral valve is of interest in bask fluid dynamic studies of the natural mitral valve and is needed for precise cardiac output estimatess by Doppler echocardiography.Methods. The velocity distribution across the mitral valve was measured by epicardial Doppler echocardiography in ten 90-kg anesthetised pigs. By routing the ultrasound transducer in 30 ° intervals from the apical position, we constructed two-dimensional velocity profiles across the left ventricular inflow tract from diameters from each rotation arranged around a reference point. The time-averaged mitral velocity profile was calculated to estimate the error in cardiac output calculations that may occur with pulsed Doppler ultrasound when a single sample volume is used to record the mean velocity across the mitral orifice.Results. The time-averaged diastolic cross-sectional mitral velocity profiles at the level of the mitral annulus and leaflet tips were variably skewed because of the development of a large anterior vortex in the left ventricle during the deceleration of early diastolk inflow and atrial systole. The ratio of the time-velocity integral of the center sample volume to the spatially averaged time-velocity integral was 1.13 ± 0.15 (mean ± SD) (range 0.80 to 1.32). Using regression analysis, we found a correlation between the degree of nonuniformity of the cross-sectional velocity distribution and the peak velocity of the anterior vortex (r = 0.65, p < 0.01).Conclusions. The assumption of a flat mean velocity profile across the mitral valve can introduce errors of +13 ± 15% (mean ± SD) in cardiac output measured with pulsed Doppler ultrasound when one is interrogating a single center sample volume.

Relationship between Leaf Movement of Trifoliolate Compound Leaf and Environmental Factors in the Soybean Canopy. II. Effects of growth and environmental conditions on diurnal changes of leaf movement.

We previously reported a method for measuring trifoliolate compound leaf movement in the soybean plant. Leaflet movement was investigated by measuring the area of triangle described by the three leaflet tips (ΔT), the distance between left and right leaflet tips, and the terminal leaflet inclination angle. Diurnal changes in trifoliolate compound leaf movement were examined with reference to leaf position on the stem, growth stages, weather conditions and soil water deficit. Trifoliolate leaf in the upper layer of the canopy, inclined to the upward in the morning, and ΔT decreased remarkably. Leaflets in the lower layer of the canopy, however, inclined to the downward all day, so ΔT did not change greatly. In clear weather, leaflets moved actively, a great decrease in ΔT was observed in midday compared with cloudy weather, due to higher solar radiation. Hysteresis was found in the relation between solar radiation and ΔT, i.e. leaflet movement was more active in the morning than in the afternoon. Leaflet movement wad most active from the late flowering to pod growth stage, and became less active with increasing plant age. Terminal leaflets were observed to become erect or inverse in response to soil water deficit, when leaf xylem water potential decreased to nearly -1.5 MPa. These results suggest that leaflet movement is mainly affected by the intensity of solar radiation, but its diurnal changes are different with leaf position, growth stage, weather and soil water condition.

Relationship between Leaf Movement of Trifoliolate Compound Leaf and Environmental Factors in the Soybean Canopy. I. Measurement of leaf movement.

著者らは, ダイズ個体群において複葉の活発な運動現象を認め, その運動パターンは個々の小葉が単独で動くのではなく, 複葉を単位として向日的に運動することを観察した. そこで, 複葉を単位とした運動の測定方法を確立し, ポットならびに圃場で栽培を行ったダイズ複葉の昼夜における運動を測定した. ダイズ複葉の運動を定量化するため, 3小葉先端を結ぶ三角形(ΔT)の面積と左右小葉間の距離(A)を測定し, それぞれ1日の最大値を100とした相対値を求めた. また, 3複葉の内最も活発に運動する頂小葉中央葉脈の方位角度(α)と傾斜角度(β)の経時変化を測定した. 早朝にはすでに3小葉は上側に傾斜角度を大きくし, ΔTは午前10時頃上側に最小となり, 夕刻になるにしたがって3小葉は徐々に水平に近くなり, ΔTは最大となった. 日没とともに3小葉は急速に垂れ下がり, ΔTは下側に小さくなったが, 午前0時以降徐々に水平から上側に傾斜角度を大きくし, 日の出前の午前4時にはΔTは上側に小さくなった. 頂小葉は太陽の運行方向に同調して, 東側から西側に旋回したことから, 頂小葉は日中向日的に運動することがわかった. 以上の結果, ダイズ複葉のΔTの変化を測定することにより, 昼間の向日運動, 夜間の就眠運動を定量化することが可能となり, ΔTは単に運動量の大小を示すのみならず, 個体群下層へ光を透過する程度を示す質的指標となることが推察された.

Potato Flea Beetle (Coleoptera: Chrysomelidae) Evaluated as a Possible Vector of Ring Rot Bacterium in Potatoes

Commercial tolerances for the incidence of bacterial ring rot caused by Clavibacter michiganense subsp. sepedonicum (Spieck. & Kotth.), Davis, Gillaspie, Vidaver &Harris in potatoes, Solanum tuberosum L., are zero, requiring strict regulations to reduce field spread of the disease. Few insects have been shown to be directly associated with the dissemination of ring rot bacteria. Concentrations of bacteria within potato leaves as potential inoculum and the ability of the potato flea beetle, Epitrix cucumeris (Harris), to acquire and disseminate the ring rot bacterium were investigated. There was considerable variation in the concentrations of ring rot bacteria within potato leaves. The highest numbers of bacteria were found in the midveins. Fewest bacteria were present in the mesophyll of the laminae, but the basal sections of laminae contained more bacteria than did the midrib sections from leaflet tips. Potato flea beetles acquired the bacteria in 24 h or less. Beetles exposed to infected plant tissue were confirmed positive for the pathogen using indirect immunofluorescence antibody staining (IFAS). In addition, scanning electron photomicrographs of infected flea beetles showed their mouthparts to be contaminated with bacteria that were the same size and morphology as the ring rot pathogen. Positive IFAS reactions of potato test plants that had been fed upon by potato flea beetles previously exposed to ring rot-infected plants represented support for transmission of the bacteria by the beetles. Mode of transmission appears to be through feeding activity because IFAS analyses of regurgitants and fecal material from contaminated beetles were negative.

Morphological determinants of echocardiographic patterns of mitral valve systolic anterior motion in obstructive hypertrophic cardiomyopathy.

The morphological determinants of mitral valve systolic anterior motion (SAM) and obstruction to left ventricular outflow in patients within the broad clinical spectrum of hypertrophic cardiomyopathy (HCM) are not completely understood, particularly the contribution of mitral leaflet length and size. To clarify this issue, mitral valve specimens from 43 patients with HCM and basal outflow obstruction were used to relate morphometric measurements of leaflet area to certain morphological and functional assessments of left ventricular outflow tract geometry and valvular motion obtained from echocardiograms in the same patients. Twenty-four patients (56%) had mitral valves of normal size (leaflet area < 12.0 cm2) and 19 patients (44%) had enlarged and elongated valves (area > or = 12.0 cm2). Compared with normal-sized mitral valves, the enlarged valves were situated more posteriorly in a larger left ventricular outflow tract (cross-sectional area, 3.3 +/- 1.0 versus 1.9 +/- 0.7 cm2 for normal-sized valves; p < 0.001) and also had greater systolic excursion of the anterior leaflet (16.2 +/- 4.5 versus 13.3 +/- 3.3 mm, p < 0.02), usually with a distinctive sharp-angled bend and localized contact of the leaflet tip with ventricular septum ("typical" SAM); this pattern of SAM was possible because the central and distal portions of the leaflet were relatively free of fibrous thickening. In contrast, normal-sized mitral valves were situated more anteriorally in a smaller left ventricular outflow tract and frequently showed a different mechanism of SAM and subaortic obstruction with relatively limited leaflet motion, absence of a sharp bend, and septal contact involving more substantial portions of the anterior leaflet and contiguous chordae ("atypical" SAM); mitral-septal apposition was effected in large measure by posterior ventricular septal motion. This pattern of SAM was invariably associated with a more diffuse pattern of fibrous thickening. Patients with obstructive HCM show patterns of mitral valve SAM that are diverse and determined largely by the interrelation of left ventricular outflow tract geometry, the size and mobility of the mitral leaflets, and the presence and distribution of fibrous thickening.

Cross-sectional echocardiographic left ventricular geometry in rheumatic mitral stenosis

The ultrastructural myopathic changes and deranged left ventricular contractile function have been reported in patients with rheumatic mitral stenosis. It is not clear if as a result of these myopathic changes, global left ventricular myocardial remodelling occurs to alter its normal elliptical shape in the absence of qualitative segmental asynchrony. To study the left ventricular cavity shape independent of chamber size, cross-sectional echocardiographically measured longest long axis (L) of the left ventricular cavity in the apical four-chamber view and short axis diameters at the level of tips of the mitral leaflets in the parasternal long axis view (D-1), of the basal cavity (D-2) and the apical segment (D-3) in the apical four-chamber view at end-diastole and their ratio, were studied in 20 patients with isolated rheumatic mitral stenosis. Twenty healthy volunteers matched for age, sex, heart rate, height and body surface area provided the normal control data. The patients with mitral stenosis had shorter long axis diameter (7.2 ± 0.7 vs 7.9 ± 0.5 cm, p < 0.001) and greater short axis/long axis diameter ratios at every level with the most pronounced change in the apical segment of the cavity ( D-3 L 0.49 ± 0.09 vs 0.40 ± 0.05, p < 0.001). Left ventricular end-diastolic sphericity index was also markedly increased in the patients with mitral stenosis (0.57 ± 0.09 vs 0.40 ± 0.05, p < 0.001). These changes in the left ventricular geometry were associated with reduced fractional shortening (29 ± 6 vs 33 ± 6%, p < 0.05), increased end-systolic volumes (25 ± 11 vs 19 ± 4 ml/m 2, p < 0.05) and increased end-systolic wall stress (70 ± 12 kilodynes/cm 2 vs 52 ± 16 kilodynes/cm 2, p < 0.001). In a prospective evaluation of 35 patients with mitral stenosis, parameters of left ventricular geometry were not related to the severity of mitral stenosis, systolic dysfunction or end-diastolic volumes. The data provide evidence for left ventricular myocardial remodelling in mitral stenosis in the absence of segmental asynchrony.

Improved reproducibility of left atrial and left ventricular measurements by guided three-dimensional echocardiography

Objectives. The objective of this study was to determine whether guided three-dimensional echocardiography could improve the reproducibility of left atrial and left ventricular anteroposterior measurements over that of standard unguided twodimensional echocardiography.Background. Although these measurements are standard indexes for evaluating chamber size, their use is limited by significant interobserver variability largely due to variable image plane positioning. To improve measurement accuracy and reproducibility, we have developed a three-dimensional echocardiograph that displays the line of intersection of the real-time image with a previously saved orthogonal reference image. This display shows the relation of the real-time image to anatomic landmarks in its third, nonvisualized dimension and may be used to guide image positioning.Methods. Three pairs of operators independently performed unguided two-dimensional and guided three-dimensional examinations on three groups of 10 patients each. The left atrium was measured in a piane through the inferior surface of the aortic cusps and the left ventricle in a plane perpendicular to its long axis 1 cm below the mitral leaflet tips. Interobserver variability of these measurements on unguided parasternal long-axis images and on guided short-axis images was assessed.Results. The standard ungnided two-dimensional examination was associated with an interobserver variability of 14.6% and 9.1% for atrial and ventricular measurements, respectively. Guided three-dimensional echocardiography significantly reduced interobserver variability to 5.0% and 3.1%, respectively, for the same measurements (p < 0.005 by McNemar's test).Conclusions. Significant interobserver variability occurs with standard unguided two-dimensional echocardiographic measurement of left atrial and left ventricular dimensions. Guided three-dimensional echocardiography achieves a nearly threefold improvement of reproducibility of these measurements and provides the basis for improved serial evaluation and comparison of atrial and ventricular size by different operators.

Cross-sectional early mitral flow-velocity profiles from color Doppler in patients with mitral valve disease.

Cross-sectional flow-velocity profiles from early mitral flow in 20 patients (10 with mitral regurgitation and 10 with mitral stenosis) were constructed from the velocity data from each point in sequentially delayed two-dimensional digital Doppler ultrasound maps. The data suggested that the early mitral flow studied in an apical four-chamber view was variably skewed in both patient groups. The maximum flow velocity overestimated the cross-sectional mean velocity at the same time by a factor of 1.12-1.86. The maximum time-velocity integral was 1.13-1.77-fold greater than the cross-sectional mean time-velocity integral. In patients with mitral regurgitation, the cross-sectional flow-velocity profile appeared to be most skewed at the level of the mitral leaflet tips. The level of the mitral annulus appeared to give the most homogenous flow-velocity distribution in both patient groups. When calculations of volume flow are based on pulsed Doppler ultrasound recordings with a single sample volume, the possibility of a skewed flow-velocity profile must be taken into account.

Transesophageal Doppler echocardiography in obstructive hypertrophic cardiomyopathy: Clarification of pathophysiology and importance in intraoperative decision making

To better understand the pathophysiology of obstruction of left ventricular outflow in hypertrophic cardiomyopathy and to determine the value of intraoperative transesophageal Doppler echocardiography in decision making, 32 consecutive patients undergoing ventriculomyectomy were assessed. The mean preoperative left ventricular outflow gradient was 83 ± 39 mm Hg and the mean basal septal width was 24 ± 6 mm. Compared with transesophageal findings in 10 normal control subjects, the mitral leaflets were longer and the coaptation point was abnormal in the patients with obstructive hypertrophic cardiomyopathy (anterior and posterior leaflet lengths in the patients were 31 ± 4 vs. 22 ± 3 mm in the control group [p < 0.00001] and 20 ± 2 vs. 15 ± 3 mm in the control group [p < 0.00001]). The coaptation point in the patient group was in the body of the leaflets at a mean of 9 ± 2 mm from the anterior leaflet tip, whereas it was at or within 3 mm of the leaflet tip in the normal group.During early systole, the distal third to half of the anterior mitral leaflet angled sharply anteriorly and superiorly (systolic anterior motion), resulting in leaflet-septal contact and incomplete mitral leaflet coaptation in mid-systole. This caused the formation of a funnel, composed of the distal parts of both leaflets, that allowed a jet of posteriorly directed mitral regurgitation to occur in mid- and late systole. The sequence of events in systole was eject/obstruct/leak.Transesophageal echocardiography was also helpful in planning the extent of the resection, assessing the immediate result and excluding important complications. In successful cases, the post-myectomy study showed 1) a dramatic thinning of the septum, with widening of the left ventricular outflow tract to a width similar to that in the normal subjects, 2) resolution of systolic anterior motion and the left ventricular outflow tract color mosaic, and marked reduction or abolition of mitral regurgitation despite persistence of abnormal mitral leaflet length and an abnormal mitral leaflet coaptation point. The routine use of transesophageal echocardiography in patients undergoing surgical myectomy for the treatment of obstructive hypertrophic cardiomyopathy is recommended.