Planimetric quantification of aortic valve stenoses using multiplanar transesophageal echocardiography

Standard techniques used in order to quantify the severity of aortic valve stenoses in clinical practice comprise: transthoracic echocardiography, namely, by determining maximum and mean transvalvular gradients and evaluating aortic valve areas, as well as invasive techniques which quantify aortic valve areas through hemodynamic pressure measurements and application of the Gorlin formula. Since the introduction of the multiplane TEE technique, it has become feasible to scan the aortic valve in a strictly horizontal plane and quantify the aortic valve orifice by planimetry. In this study, we investigated 23 patients with various degrees of aortic valve stenoses. We compared aortic valve areas, which had been planimetrically determined by multiplane TEE scans, and mean aortic valve gradients (standard TEE technique) with pressure gradients and valve areas derived from hemodynamic measurements obtained during cardiac catheterization, and have found that the valve areas as well as the mean pressure gradients correlate well.     

Effects of dobutamine on aortic valve indexes in asymptomatic patients with bileaflet mechanical prostheses in the aortic valve position

We investigated the effects of alternating transvalvular flow rate on Doppler-derived aortic valve resistance and valve area in asymptomatic patients with mechanical aortic valve replacement under dobutamine infusion. The Gorlin-derived aortic valve area and continuity equation-derived aortic valve area seem to be less flow dependent; valve resistance tends to be flow dependent.     

Application of color Doppler flow mapping to calculate orifice area of St Jude mitral valve

BACKGROUND: The effective orifice area (EOA) of a prosthetic valve is superior to transvalvular gradients as a measure of valve function, but measurement of mitral prosthesis EOA has not been reliable. METHODS AND RESULTS: In vitro flow across St Jude valves was calculated by hemispheric proximal isovelocity surface area (PISA) and segment-of-spheroid (SOS) methods. For steady and pulsatile conditions, PISA and SOS flows correlated with true flow, but SOS and not PISA underestimated flow. These principles were then used intraoperatively to calculate cardiac output and EOA of newly implanted St Jude mitral valves in 36 patients. Cardiac output by PISA agreed closely with thermodilution (r=0.91, Delta=-0.05+/-0.55 L/min), but SOS underestimated it (r=0.82, Delta=-1.33+/-0.73 L/min). Doppler EOAs correlated with Gorlin equation estimates (r=0.75 for PISA and r=0.68 for SOS, P<0.001) but were smaller than corresponding in vitro EOA estimates. CONCLUSIONS: Proximal flow convergence methods can calculate forward flow and estimate EOA of St Jude mitral valves, which may improve noninvasive assessment of prosthetic mitral valve obstruction.     

Mitral valve area in combined mitral stenosis and regurgitation

Eight patients with mixed mitral stenosis and regurgitation underwent hemodynamic and angiographic study prior to mitral valve replacement. The stenotic orifice of the mitral valve was calculated employing the total left ventricular stroke volume by cineangiography as the numerator of the Gorlin Formula. Excellent agreement with the measured orifice of the mitral valve was obtained using a value of 37.9 (0.85 X 44.5) for the constant in the Gorlin formula as recommended by Cohen and Gorlin. Recalculation of this constant independently by our data yielded a value that was almost identical. Regurgitant flows and orifice sizes were calculated for each patient using the same constant as for calculation of the stenotic orifices.     

Enhancement of opsin activity by all-trans-retinal

This study examines the hemodynamic performance of small size St. Jude BioImplant aortic prostheses using dobutamine echocardiography. Eleven patients (3 women, mean age 75 years) who had undergone aortic valve replacement with a size 21-mm St. Jude BioImplant aortic prostheses at 10.8 +/- 5.1 months (SD) previously were studied. Dobutamine infusion was started at a rate of 5 microg/kg/min and increased to 10 microg/kg/min, and subsequently to 20 microg/kg/min at 15-minute intervals. Pulsed and continuous-wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, mean gradient, and the performance index across each prosthesis were calculated and cardiac output was determined by Doppler measurement of flow in the left ventricular outflow tract. Stress dobutamine increased heart rate and cardiac output by 51% and 56%, respectively (both p <0.0001), and the mean transvalvular gradient increased from 30.1 +/- 7.5 mm Hg at rest to 49.3 +/- 11.5 mm Hg at maximum stress (p <0.0005). The performance index increased progressively from 0.29 +/- 0.05 at rest to 0.40 +/- 0.10 at maximum stress (p <0.0005). Regression modeling analyses demonstrated that the maximum stress gradient was independent of all variables except the resting gradient (p = 0.03). Body surface area had no effect on the changes in cardiac output, effective orifice area, or transprosthetic gradient at maximum stress. Thus, these data demonstrate that the size 21-mm St. Jude BioImplant prosthesis exhibits suboptimal hemodynamic performance with transvalvular gradients consistent with mild to moderate aortic stenosis, both at rest and under stress conditions.     

Early clinical and hemodynamic evaluation of the aortic intact porcine bioprosthesis

Between October 1990 and June 1992, 89 patients underwent aortic valve replacement using the Intact porcine bioprosthesis. Their mean age (+/- SD) was 74.6 +/- 7.8 years (range 48 to 92). Seventy-five percent were in NYHA Class III-IV, 79 (89%) had AS or AS/AI, 10 (11%) had had previous cardiac surgery and 25 (32%) had an EF < 0.50. Associated procedures included CABG 45 (51%), septal myectomy 13 (15%), annular enlargement eight (9%), LV aneurysmectomy one, ascending aortic replacement one, and arch replacement one. Hospital mortality was four (4.5%). Hemodynamics were assessed with 2D echo with Doppler at seven days, six weeks and 12 months, and compared with 130 standard Carpentier-Edwards (C-E) porcine bioprostheses. At follow up, two patients have 2/4 perivalvular AI. The transvalvular gradients for the Intact valve were as follows: 21 mm-16.9 +/- 7.4 mmHg; 23 mm-18.9 +/- 6.2 mmHg; 25 mm-17.1 +/- 5.4 mmHg; 27 mm-15.0 +/- 3.7 mmHg; and 29 mm-15.0 +/- 2.1 mmHg. When compared to the standard Carpentier-Edwards porcine bioprostheses, the 21 mm Intact valve had the same gradient as the C-E prosthesis. However, the transvalvular gradients were slightly higher for the Intact valve for sizes 23-29 mm when compared to the corresponding C-E valve. The effective orifice area and effective orifice area index was no different between the two valves. Satisfactory hemodynamics are seen in the smaller prostheses when valves are matched for BSA and when aortic annular enlargement is performed when necessary.     

Comparison of proximal isovelocity surface area method with pressure half-time and planimetry in evaluation of mitral stenosis

OBJECTIVES: This study sought to 1) compare the accuracy of the proximal isovelocity surface area (PISA) and Doppler pressure half-time methods and planimetry for echocardiographic estimation of mitral valve area; 2) evaluate the effect of atrial fibrillation on the accuracy of the PISA method; and 3) assess factors used to correct PISA area estimates for leaflet angulation. BACKGROUND: Despite recognized limitations of traditional echocardiographic methods for estimating mitral valve area, there has been no systematic comparison with the PISA method in a single cohort. METHODS: Area estimates were obtained in patients with mitral stenosis by the Gorlin hydraulic formula, PISA and pressure half-time method in 48 patients and by planimetry in 36. Two different factors were used to correct PISA estimates for leaflet angle (theta): 1) plane-angle factor (theta/180 [theta in degrees]); and 2) solid-angle factor [1-cos(theta/2)]. RESULTS: After exclusion of patients with significant mitral regurgitation, the correlation between Gorlin and PISA areas (0.88) was significantly greater (p < 0.04) than that between Gorlin and pressure half-time (0.78) or Gorlin and planimetry (0.72). The correlation between Gorlin and PISA area estimates was lower in atrial fibrillation than sinus rhythm (0.69 vs. 0.93), but the standard error of the estimate was only slightly greater (0.24 vs. 0.19 cm2). The average ratio of the solid- to the plane-angle correction factors was approximately equal to previously reported values of the orifice contraction coefficient for tapering stenosis. CONCLUSIONS: 1) The accuracy of PISA area estimates in mitral stenosis is at least comparable to those of planimetry and pressure half-time. 2) Reasonable accuracy of the PISA method is possible in irregular rhythms. 3) A simple leaflet angle correction factor, theta/180 (theta in degrees), yields the physical orifice area because it overestimates the vena contracta area by a factor approximately equal to the contraction coefficient for a tapering stenosis.     

Doppler haemodynamic assessment of clinically and echocardiographically normal mitral and aortic Allcarbon valve prostheses. Valve Prostheses Ligurian Cooperative Doppler Study

Doppler echocardiographic characteristics of normally functioning Allcarbon prostheses were studied in 149 consecutive patients with 157 valves in the mitral (n = 73) and aortic (n = 84) positions whose function was considered normal by clinical and echocardiographic evaluation. In the mitral position, the mean gradient and the effective mitral orifice area were not significantly different in either the 25-mm or the 31-mm size valves (from 5 +/- 1 to 4 +/- 1 mmHg and from 2.2 +/- 0.6 to 2.8 +/- 0.9 cm2, respectively; P = ns for both). Conversely, peak gradient was significantly and inversely correlated to actual orifice area (r = -0.70; P < 0.0006), decreasing from 15 +/- 3 mmHg in the 25-mm size valve to 9 +/- 1 mmHg in the 31-mm size. In the aortic position, the mean gradient was 29 +/- 8 mmHg in the 19-mm size valve; it decreased to 8 +/- 2 mmHg in the 29-mm size. Effective prosthetic aortic valve area, calculated using the continuity equation, ranged between 0.9 +/- 0.1 cm2 for the 19-mm size valve to 4.1 +/- 0.7 cm2 for the 29-mm size. By analysis of variance, effective prosthetic aortic valve area differentiated various valve sizes (F = 25.3; P < 0.0001) better than peak (F = 5.34; P = 0.012) or mean (F = 4.34; P = 0.0052) gradients alone, and it correlated better with actual orifice area (r = 0.89, r = -0.70 and r = -0.65, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Multicenter study of stentless valve replacement in the small aortic root

OBJECTIVE: A clinical study was conducted to evaluate the results of stentless porcine valves in patients with a small aortic root (19- and 21-mm aortic anulus). METHODS: Of 567 patients, from 4 surgical institutions, 171 patients (30.1%) had a small aortic root, comprising 163 cases with calcified aortic stenosis and 8 cases with predominant valvular insufficiency. Sixty patients had associated mitral or coronary lesions. Mean age was 72 +/- 4.2 years. Forty-seven patients with a small aortic root had a 19-mm anulus, and 124 patients had a 21-mm anulus. The body surface area was, respectively, 1.55 +/- 0.2 m2 and 1.78 +/- 0.45 m2. Hemodynamic evaluation of the stentless valve comprised serial measures of mean gradients, effective orifice area, and left ventricular mass reduction. Complication rates for secondary events were evaluated over a 6-year period. RESULTS: The hospital mortality rate was 3.5%. The mean gradients after the first year were 9 +/- 2 mm Hg and 6 +/- 1.7 mm Hg in patients with a 19-mm and a 21-mm anulus, respectively. Effective orifice area was 1.45 +/- 0.3 cm2 and 1.72 +/- 0.4 cm2. Gradients and surfaces remained stable throughout the study period. Aortic regurgitation was zero to trace. Left ventricular mass at discharge and at 1 year were, respectively, 296 +/- 127 g and 215 +/- 102 g for patients with a 19-mm anulus and 281 +/- 75 g and 236 +/- 15 g for patients with a 21-mm anulus. CONCLUSIONS: Stentless valves are a suitable device for elderly patients with small aortic roots, which leave only mild residual obstruction.     

Retrograde coronary artery flow in aortic valve disease

Retrograde coronary artery flow was observed angiographically in 43 patients with aortic stenosis and/or regurgitation. In the 24 patients with pure or predominant aortic stenosis, retrograde flow was seen in all 24 during end-systole. In the eight patients with pure aortic regurgitation, retrograde flow was seen mainly during end-diastole (6/8). Among the 11 patients with stenosis and regurgitation, retrograde flow was both end-systolic and enddiastolic. Dominant left coronary arteries were seen in 13 patients; 13 showed retrograde flow in the dominant arteries. Dominant right coronary arteries were seen in 25 patients: all 25 showed retrograde flow equally in the right and left coronary. Five of the 43 patients could not be evaluated for dominance because of coronary artery occlusions. The severity of retrograde flow did not correlate with usual clinical, hemodynamic or tension-stress parameters: angina, electrocardiographic abnormality, end-diastolic pressure or volume, end-systolic pressure or volume, ejection fraction, severity of aortic regurgitation, peak or mean valve gradient, aortic valve area, myocardial tension and stress calculations, or DPTI:SPTI. In summary, retrograde coronary artery flow was seen in all 43 patients with severe aortic valve disease. The time in the cardiac cycle when retrograde flow occurred was related to the type of valve disease. Retrograde flow was seen mainly in the coronary arteries supplying the left ventricle and may result from increased regional myocardial stresses.     

Impact of size mismatch and left ventricular function on performance of the St. Jude disc valve after aortic valve replacement

BACKGROUND: The hemodynamic function of the St. Jude valve may change relative to changes in left ventricular function after aortic valve replacement for aortic stenosis. From theoretical reasons one may hypothesize that prosthetic valve hemodynamic function is related to left ventricular failure and mismatch between valve size and patient/ventricular chamber size. METHODS: Forty patients aged 24 to 82 years who survived aortic valve replacement for aortic stenosis with a standard St. Jude disc valve (mean size, 23.5 mm; range, 19 to 29 mm) were followed up prospectively with Doppler echocardiography and radionuclide left ventriculography preoperatively and 9 days, 3 months, and 18 months after the operation with assessment of intravascular hemolysis at 18 months. Follow-up to a maximum of 7.4 years (mean, 6.3 years) was 100% complete. RESULTS: Left ventricular muscle mass index decreased from 198 +/- 62 g.m-2 preoperatively to 153 +/- 53 g.m-2 at 18 months (p < 0.001), paralleled by a significant increase in left ventricular ejection fraction, peak ejection rate, and peak filling rate; only 18% of the patients had normal left ventricular muscle mass index and only 32% normal ventricular function (normal left ventricular ejection fraction, peak ejection rate, peak filling rate, early filling fraction, and late filling fraction during atrial contraction) at 18 months. Prosthetic valve peak Doppler gradient dropped from 20 +/- 6 mm Hg at 9 days to 17 +/- 5 mm Hg at 18 months (p < 0.05). Reduction of left ventricular muscle mass index was unrelated to peak gradient and size of the valve. Peak gradient at 18 months rose with valve orifice diameter of 17 mm or less (by 6 mm Hg), orifice diameter/body surface area of 9 mm.m-2 or less (by 5 mm Hg), left ventricular enddiastolic dimension (by 23 mm Hg per 10 mm increase), and impaired ventricular function (by 3 mm Hg). All but 2 patients (5%) had intravascular hemolysis; none had anemia. Two patients with moderate paravalvular leak had the highest serum lactic dehydrogenase levels; 4 patients with trivial leak had higher serum lactic dehydrogenase levels than those without leak. Serum lactic dehydrogenase levels rose with moderate paravalvular leak, impaired ventricular function, and valve orifice diameter. Six patients with trivial or moderate paravalvular leak had a cumulative 7-year freedom from bleeding and thromboembolism of 44% +/- 22% compared with 87% +/- 5% for those without leak (p < 0.05). CONCLUSIONS: The peak gradient of the St. Jude aortic valve dropped marginally over the first 18 postoperative months in association with incomplete left ventricular hypertrophy regression and marginal improvement of ventricular function. Mismatch between valve size and ventricular cavity size or patient size and impaired function of a dilated ventricle significantly compromised the performance of the St. Jude valve. Probably explained by platelet destruction or activation, paravalvular leak was related to bleeding and thromboembolic complications.     

Hemodynamic function of the Hancock standard orifice aortic valve bioprosthesis

Reports that the hemodynamic performance of the standard orifice aortic bioprosthesis in less than optimal have prompted recommendations that mechanical prosthesis or anulus-enlarging procedures be used in adult patients with a small aortic root. The hemodynamic function of the Hancock bioprosthesis was evaluated in 77 patients who underwent cardiac catheterization of rest and with isoproterenol infusion (15 patients) an average of 6 months after operation. The average peak systolic gradient (basal conditions) was 7 mm Hg (range 0 to 37 mm Hg); 35 patients had no resting gradient. Fifteen patients received 21 mm diameter valves and had an average systolic valve gradient of 10 mm Hg (range 0 to 30 mm Hg); the average effective valve orifice area was 1.27 +/- 0.17 cm2 for 21 mm, 1.46 +/- 0.11 cm2 for 23 mm, 1.72 +/- k0.20 cm2 for 25 mm, and 1.97 +/- 0.06 for 27 mm bioprostheses. Isoproterenol infusion, elevating cardiac output 66%, increased the peak systolic gradient from an average of 11 mm Hg (range 0 to 37 mm Hg) to 44 mm Hg (range 10 to 85 mm Hg). It is concluded that small-diameter (21 and 23 mm) Hancock bioprostheses can be used with acceptable clinical and hemodynamic function in patients with a small body surface area.     

Assessment of accuracy of the Doppler pressure half-time method in the estimation of the mitral valve area immediately after balloon mitral valvuloplasty

AIM: The reliability of Doppler echocardiography in determining the mitral valve area after balloon mitral valvuloplasty has been questioned, as discrepancies were noted between measurements obtained by the pressure half-time method and those derived haemodynamically, immediately following completion of the procedure. Recent investigations, however, have indicated that these discrepancies may be attributable to the over-estimation of the mitral valve area by haemodynamic measurements, caused by the presence of the iatrogenic atrial septal defect complicating transseptal catheterization. The aim of the present study was to further test this hypothesis. METHODS AND RESULTS: Measurements of the mitral valve area by the Doppler pressure half-time method and the Gorlin formula were obtained and compared in 238 consecutive patients before and immediately after retrograde non-transseptal balloon mitral valvuloplasty, which does not involve puncture and/or dilatation of the inter-atrial septum. No significant difference was found between Doppler- and Gorlin-derived measurements, neither before (1.04 +/- 0.23 vs 1.03 +/- 0.23 cm2, P = ns) nor immediately after (2.14 +/- 0.47 vs 2.12 +/- 0.49 cm2, P = ns) valvuloplasty. Linear regression analysis demonstrated a high degree of correlation between Doppler and Gorlin measurements before (r = 0.778) and after (r = 0.886) the procedure. Good agreement was confirmed by the Bland-Altman method. CONCLUSION: Doppler echocardiography yields accurate measurements of the mitral valve area immediately after retrograde non-transseptal balloon mitral valvuloplasty. This finding supports the hypothesis that the creation of an iatrogenic atrial septal defect during transseptal catheterization may contribute to the poor agreement between Doppler and Gorlin data after balloon mitral valvuloplasty.     

Phasic changes in human right coronary blood flow before and after repair of aortic insufficiency

We have shown previously that acute aortic insufficiency in chronically instrumented dogs reverses the normally high ratio of diastolic to systolic coronary blood flow. Phasic blood flow in the dominant right coronary artery was measured directly with an electromagnetic flow meter during surgery in eight patients with severe aortic insufficiency before and after relacement of the aortic valve. Before the insufficiency was eliminated, right coronary flow average 116 +/- 37 ml./minute and the diastolic to systolic flow ratio was 0.88 +/- 17. Mean arterial blood pressure averaged 106 +/- 17 mm. Hg, heart rate 84 +/- 19 beats/minute, and mean diastolic pressure averaged 67 +/- 10 mm. Hg. After the aortic valve was replaced with an average heart rate of 90 +/- 15 and mean blood pressure of 103 +/- 13 mm. Hg, the average right coronary blood flow increased to 180 +/- 40 ml./minute with a D/S ratio of 2.18 +/- 0.8. In all cases the right coronary blood flow increased after the aortic insufficiency was eliminated surgically. Right coronary flow probably increased because of the improved diastolic perfusion pressure and the change from predominantly systolic to diastolic coronary flow.     

Small aortic annulus: a functional definition

Background & objective: Small aortic annulus is conventionally associated with poor outcome after aortic valve replacement (AVR). Contrarily, several patients have excellent follow-up results after AVR with 19, 20 or 21 size Medtronic Hall (MH) or Sorin Carbocast (SC) prostheses. This disparity prompted a relook at the semantics of a small aortic annulus. METHODS: Available survivors of isolated AVR with #19, #20 or #21 prostheses - 13 with 19 SC or 20 MH valves (Group A) and 29 with 21 SC or MH valves (Group B) were studied. Disparity between actually implanted prostheses versus predicted prosthetic size (tissue annulus diameter) was analysed according to nomograms of Rowlatt et al, NIH Plehn, Kishimoto formula and Sievers composite criteria. Preoperative and follow-up echocardiographic assessments were used for hemodynamic and prosthetic function indices. RESULTS: Both groups were similar in age, height, weight, BSA, BMI, mean NYHA class, CTR, preoperative peak gradient (PG) (92. 0 +/- 29.55 vs 102.88 +/- 33.65), mean gradient (MG) (56.8 +/- 24.6 vs 61.55 +/- 16.56), LVEDD (50.75 +/- 10.92 vs 56.0 +/- 13.5), LVESD (34.37 +/- 13.32 vs 38.52 +/- 13.85) and LVEF (67.5 +/- 12.5 vs 63.9 +/- 14.3). By developmental indices of Rowlatt et al. and NIH, no valve annulus could be designated as narrow. By Sievers composite nomogram all implanted valves were undersized by echocardiographic parameters, in normal range by angiographic criteria and oversized by anatomic autopsy data. Implanted valves in both groups were bigger than Plehn-predicted size (18.16 +/- 1.48 in GrA, 19.46 +/- 1. 10 in GrB). Valve size indices (VSI) (GrA 16.16 +/- 2.85 GrB 14.24 +/- 1.64) and geometric orifice area indices (VAI: valve area index) (GrA 1.50 +/- 0.28 vs 1.41 +/- 0.19) and postoperative rest PG (GrA 47.2 +/- 18.6 GrB 33.8 +/- 9.9) and MG (GrA 27.2 +/- 12.9 vs 19.0 +/- 9.9) were acceptable. LVEDD and LVESD regressed in both groups. LV mass indices regressed from 218.56 +/- 100.85 to 128.17 +/- 27.7 in GrA and 238.94 +/- 102.5 to 134.22 +/- 34.72 in GrB. Performance indices of implanted valves and postoperative aortic valve resistances were correlative. CONCLUSIONS: The size of the implanted prostheses per se does not denote narrowness. Patient-prosthesis mismatch may be considered if predicted prosthesis has VSI <12 mm/m2, VAI <1.31 cm2/m2 or prosthesis orifice diameter <19 mm which may indicate annular enlargement.     

Prognosis after valve replacement in patients with severe aortic stenosis and a low transvalvular pressure gradient

OBJECTIVES: This study was conducted to determine the risks and benefits of valve replacement in patients with severe aortic stenosis and a low transvalvular pressure gradient. BACKGROUND: There is uncertainty regarding the appropriate management of adults with severe aortic stenosis and a transvalvular pressure gradient < or = 30 mm Hg. With only six such patients reported, one study suggested that these subjects have a prohibitive operative risk and little symptomatic improvement if they survive surgical treatment, whereas another showed that they can survive an operation and improve symptomatically. METHODS: In an attempt to clarify the risks and benefits of valve replacement in these patients, we reviewed the records of 18 patients (15 men and 3 women, aged 49 to 81 years) with severe aortic stenosis (valve area < or = 0.4 cm2/m2 body surface area), a mean transvalvular pressure gradient < or = 30 mm Hg and limiting symptoms (New York Heart Association functional class III or IV) who underwent valve replacement. RESULTS: Six patients (33%) (95% confidence interval 13% to 59%) died perioperatively, whereas 10 patients (56%) (95% confidence interval 31% to 78%) improved symptomatically to functional class I (n = 8) or II (n = 2) (p = NS in comparison with the 6 who died). No clinical or hemodynamic variable was predictive of survival or improvement in functional class. CONCLUSIONS: Valve replacement in patients with severe aortic stenosis and a transvalvular pressure gradient < or = 30 mm Hg is accompanied by a considerable operative risk. Although there were no significant differences in this small series between the fraction of patients who died and those who exhibited improvement, we still recommend the procedure because many patients survive the operation and most of the survivors show an improved symptomatic status.     

Improvement in mitral regurgitation after aortic valve replacement

This study sought to determine whether there is a quantitative improvement in mitral regurgitation (MR) after aortic valve replacement (AVR) for aortic stenosis (AS) and, if so, the mechanisms for this change. MR frequently accompanies AS. The addition of mitral valve replacement to AVR significantly increases the risk of surgery. Although previous studies have suggested a qualitative improvement in MR severity after AVR, semiquantitative analysis of this improvement has not been documented nor have the underlying mechanisms been examined. We evaluated 28 patients who had undergone 2-dimensional echo and color flow Doppler imaging an average of 1.5 +/- 2.5 months before and 2.5 +/- 4.2 months after AVR. Maximum MR area, MR percentage (MR area/left atrial area), mitral annular area, left atrial area, aortic gradient, and parameters of left ventricular geometry were measured to evaluate MR severity and to assess functional mechanisms for improvement in MR. There was a significant decrease in MR area (5.5 +/- 2.8 cm2 vs 2.5 +/- 1.9 cm2, p < or =0.0001) and MR percentage (25 +/- 11% vs 12 +/- 10% after operation, p < or =0.0001) between preoperative and postoperative studies. There was a significant reduction in aortic gradient, mitral annular area, left atrial area, and left ventricular length postoperatively. In univariate analysis, MR improvement was related to the lower preoperative left ventricular fractional area change (p = 0.027) and to the changes in fractional area change (p = 0.001) and left ventricular systolic area (p = 0.001). Thus, improvement in MR after AVR is related to changes in left ventricular function postoperatively. These data suggest that reduction in MR is due not only to decreased intraventricular pressure, but also to changes in ventricular morphology.     

Adjustable tricuspid valve annuloplasty assisted by intraoperative transesophageal color Doppler echocardiography

Intraoperative transesophageal echocardiography (TEE) can play a major role in active guidance of cardiac surgery. This study describes a new application of TEE for assisting tricuspid suture annuloplasty. Twenty-five patients (aged 52 +/- 11 years) who underwent mitral valve replacement and tricuspid valve annuloplasty were studied intraoperatively by TEE. After cardiopulmonary bypass, the suture annuloplasty was adjusted on the beating heart until palpable regurgitation was eliminated. Further adjustment of the suture was performed under echocardiographic guidance until color Doppler flow imaging showed the most adequate correction of tricuspid regurgitation (TR). A significant decrease in the semiquantitative grade of TR, of regurgitant jet area and of the ratio jet area/right atrial area was obtained when the suture was adjusted under echocardiographic guidance. The peak inflow velocity and the gradient across the tricuspid valve did not show significant changes throughout the procedures. The results showed that the tricuspid suture annuloplasty guided by TEE enables a substantial reduction in residual TR without creating valve stenosis.     

TRH receptor

OBJECTIVES: Flow variations can affect valve-area calculation in aortic stenosis and lead to inaccuracies in the evaluation of the stenosis. Knowing that transvalvular flow varies normally within one beat, we designed this study to assess the response of the valve to intrabeat variation of flow during systole. Results were compared with flow-derived measurements. BACKGROUND: Technological improvements now allow us to evaluate aortic valve area directly by short axis planimetry. This offers the possibility to perform serial planimetries during one ejection phase and analyze the intrabeat dynamic behavior of the stenotic-aortic valve and compare these measurements with flow-derived measurements. METHODS: Forty echocardiograms displaying different degrees of aortic stenosis were analyzed by frame-by-frame planimetry of the valve area from onset of opening to complete closure. Maximal-mean area, opening and closing rates and ejection times were obtained and compared with Doppler-derived data. RESULTS: Valve area varied during ejection. Stenotic valves opened and closed more slowly than normals and remained maximally open for a shorter period. Mean area by Doppler data corresponded more closely to maximal than to mean-planimetered area. Duration of flow was shorter than valve opening in severely stenotic valves. Discrepancies between Doppler-derived and two-dimensional (2D) measurements decreased in less stenotic valves. CONCLUSIONS: Our observations reveal striking differences between the dynamics of normal and stenotic valves. Surprisingly, Doppler-derived mean-valve area correlated better with maximal-anatomic area than with mean-anatomic area in patients with aortic stenosis. Discrepancies between duration of flow and valve opening could explain this phenomenon.     

Re: Proportionate mortality among union members employed at three Texas refineries

OBJECTIVES:We established an in vitro model to investigate the effects of valve sizing on the hemodynamic characteristics and leaflet motion of the Toronto SPV valve (St Jude Medical, Inc, St Paul, Minn). METHODS: Nine valves were first implanted in fresh porcine aortic roots and then retested in glutaraldehyde-treated porcine aortic roots. Three valves were 1- to 2-mm oversized, 3 were 1- to 2-mm undersized, and there were 3 size-for-size implantations. The elasticities of the aortic roots and the composite roots were measured in the pressure range between 0 and 120 mm Hg, and the composite roots were then tested in a pulsatile flow simulator. The transvalvular gradient and regurgitation were measured and the effective orifice area and performance index were calculated for each root. Leaflet motion was recorded on videotape. RESULTS: The external diameter of the fresh root increased by 35% as the hydrostatic pressure rose from 0 to 120 mm Hg, as compared with 11% for the glutaraldehyde-treated root. Valve implantation in the fresh root reduced the distensibility to 22% but did not change distensibility in the glutaraldehyde-treated root. The effective orifice area was dependent on the valve size, with the transvalvular gradient decreasing as the valve size increased. For the same size of valve the hydrodynamic parameters were slightly better if the valve was undersized by 1 mm. A significant difference in favor of the undersized valves was found in open-leaflet bending deformation. CONCLUSION: Leaflet motion of the stentless porcine aortic valve in vitro is improved if the valve is slightly undersized, and this may be beneficial to the long-term durability of the prosthesis.