Hemodynamic Comparison by Doppler Echocardiography of Valves in the Aortic Position: Value of the Continuity Equation to Assess Prosthetic Dysfunction

In 281 patients, we used Doppler echocardiography to compare the hemodynamic performance of different aortic prosthetic valves at three postoperative stages and investigated the value of the continuity equation in diagnosing aortic prosthetic obstruction. A baseline study was performed in 163 patients, a 5 +/- 2-month follow-up study was performed in 103 patients, and a 15 +/- 5-month follow-up study was performed in 65 patients. From baseline to the second study, left ventricular diastolic diameter, heart rate, and maximum (MG) and mean Doppler-derived gradient (MeG) decreased significantly, and left ventricular shortening fraction, systolic blood pressure, stroke volume, and prosthetic valvular area (PVA) increased significantly. No changes were found between the second and third studies. Thus, noninvasive hemodynamic values at the time of follow-up are reported in 171 patients: 86 with Bj?rk-Shiley Monostrut, 27 with Carbomedics, 11 with Medtronic-Hall, 18 with Hancock modified, and 29 with Toronto valve bioprosthesis. Patients implanted with the Toronto had a larger prosthetic size (Monostrut 23 +/- 2 mm, Carbomedics 23 +/- 3 mm, Medtronic-Hall 23 +/- 2 mm, Hancock 23 +/- 2 mm, Toronto 25 +/- 2 mm, P < 0.01) despite a similar body surface area. MeG and MG were lower (MeG [in mmHg] Monostrut 12 +/- 5, Carbomedics 14 +/- 6, Medtronic-Hall 19 +/- 6, Hancock 11 +/- 4, Toronto 7 +/- 5; P < 0.01 between Toronto and all others), and PVA was greater (Monostrut 2.0 +/- 0.7 cm(2), Carbomedics 1.8 +/- 0.8 cm(2), Medtronic-Hall 1.6 +/- 0.7 cm(2), Hancock 1.7 +/- 0.5 cm(2), Toronto 2.2 +/- 0.9 cm(2); P < 0.01 between Toronto and Carbomedics, Medtronic-Hall, and Hancock), even compared with the same sizes in the other valves. A PVA of 0.9 cm(2) or less and MeG of 28 mmHg or more identified prosthetic obstruction with 100% sensitivity and 99% specificity. Hemodynamics change significantly from the early to the late postoperative state. The Toronto valve stentless porcine bioprostheses performs hemodynamically better than other valves. PVA measurement using the continuity equation may accurately identify prosthetic obstruction.     

Effect of prosthetic aortic valve design on the Doppler-catheter gradient correlation: an in vitro study of normal St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves.

To evaluate the normal range of Doppler-derived velocities and gradients, their relation to direct flow measurements and the importance of prosthetic valve design on the relation between Doppler and catheter-derived gradients, five sizes of normal St. Jude bileaflet, Medtronic-Hall tilting disc, Starr-Edwards caged ball and Hancock bioprosthetic aortic valves were studied with use of a pulsatile flow model. A strong linear correlation between peak velocity and peak flow, and mean velocity and mean flow, was found in all four valve types (r = 0.96 to 0.99). In small St. Jude and Hancock valves, Doppler velocities and corresponding gradients increased dramatically with increasing flow, resulting in velocities and gradients as high as 4.7 m/s and 89 mm Hg, respectively. The ratio of velocity across the valve to velocity in front of the valve (velocity ratio) was independent of flow in all St. Jude, Medtronic-Hall, Starr-Edwards and Hancock valves when the two lowest flow rates were excluded for Hancock valves. Although Doppler peak and mean gradients correlated well with catheter peak and mean gradients in all four valve types, the actual agreement between the two techniques was acceptable only in Hancock and Medtronic-Hall valves. For St. Jude and Starr-Edwards valves, Doppler gradients significantly and consistently exceeded catheter gradients with differences as great as 44 mm Hg. Thus, Doppler velocities and gradients across normal prosthetic heart valves are highly flow dependent. However, the velocity ratio is independent of flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Jamming of prosthetic heart valves by suture trapping: experimental findings

The vulnerability of the Medtronic-Hall, Bj?rk-Shiley Monostrut, Duromedics, and St. Jude Medical valves to occluder immobilization by sutures was determined under static and pulsatile flow conditions. Variables were cardiac output, cross-sectional diameter of suture, type of suture (braided versus monofilament) and position of the offending suture along the circumference of the valve ring. Under static conditions, pressures, ranging from 40 to 340 mmHg and 10 to 170 mmHg, were required to decompress obstructed Medtronic-Hall and Bj?rk-Shiley Monostrut valves, respectively. As a result of different design characteristics and different occluder/orifice clearances the Medtronic-Hall valve showed its maximum opening pressure in case of interference with sutures at the axis of symmetry in both minor and major orifices, whereas for the Bj?rk-Shiley Monostrut valve this was reached in the minor orifice. Under pulsatile flow conditions, in case of interference with Prolene 2-0 suture, the Duromedics valve showed irregularly delayed opening and an opening pressure difference of 50 mmHg at a cardiac output of 8 L/min, whereas leaflet motion and pressure difference in the St. Jude Medical valve were undisturbed under similar conditions. The necessary pressure difference for opening the Medtronic Hall valve reached 44mmHg at a cardiac output of 8 L/min. High and low risk of extrinsic leaflet obstruction in the Duromedics and St. Jude Medical valves, respectively, is related to the design of the hinge mechanisms and the wedge angle of their leaflets (2 degrees versus 25 degrees). Precautionary principles in implantation of prosthetic heart valves are stressed to prevent the potentially lethal complication of occluder immobilization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler assessment of prosthetic valve orifice area. An in vitro study.

BACKGROUND. Although Doppler echocardiography has been shown to be accurate in assessing stenotic orifice areas in native valves, its accuracy in evaluating the prosthetic valve orifice area remains undetermined. METHODS AND RESULTS. Doppler-estimated valve areas were studied for their agreement with catheter-derived Gorlin effective orifice areas and their flow dependence in five sizes (19/20-27 mm) of St. Jude, Medtronic-Hall, and Hancock aortic valves using a pulsatile flow model. Doppler areas were calculated three ways: using the standard continuity equation; using its simplified modification (peak flow/peak velocity); and using the Gorlin equation with Doppler pressure gradients. The results were compared with Gorlin effective orifice areas derived from direct flow and catheter pressure measurements. Excellent correlation between Gorlin effective orifice areas and the three Doppler approaches was found in all three valve types (r = 0.93-0.99, SEE = 0.07-0.11 cm2). In Medtronic-Hall and Hancock valves, there was only slight underestimation by Doppler (mean difference, 0.003-0.25 cm2). In St. Jude valves, however, all three Doppler methods significantly underestimated effective orifice areas derived from direct flow and pressure measurements (mean difference, 0.40-0.57 cm2) with differences as great as 1.6 cm2. In general, the modified continuity equation calculated the largest Doppler areas. When orifice areas were calculated from the valve geometry using the area determined from the inner valve diameter reduced by the projected area of the opened leaflets, Gorlin effective orifice areas were much closer to the geometric orifice areas than Doppler areas (mean difference, 0.40 +/- 0.31 versus 1.04 +/- 0.20 cm2). In St. Jude and Medtronic-Hall valves, areas calculated by either technique did not show a consistent or clinically significant flow dependence. In Hancock valves, however, areas calculated by both the continuity equation and the Gorlin equation decreased significantly (p less than 0.001) with low flow rates. CONCLUSIONS. Doppler echocardiography using either the continuity equation or Gorlin formula allows in vitro calculation of Medtronic-Hall and Hancock effective valve orifice areas but underestimates valve areas in St. Jude valves. This phenomenon is due to localized high velocities in St. Jude valves, which do not reflect the mean velocity distribution across the orifice. Valve areas are flow independent in St. Jude and Medtronic-Hall prostheses but decrease significantly with low flow in Hancock valves, suggesting that bioprosthetic leaflets may not open fully at low flow rates.     

Use of Hancock porcine xenografts in children and adolescents

Between January 1,1974 and December 31,1978,47 xenografts (8 aortic, 28 mitral, 4 tricuspid, 3 left atrioventricular valve in I-transposition of the great arteries and 3 aortic-mitral) were implanted in 44 patients, aged 10/12 to 20 5/12 years (median 12 2/12). All eight patients with aortic valve replacement survived and were followed up for 22.5 ± 10.4 months (mean ± standard error of the mean). At postoperative cardiac catheterization in three patients, the peak systolic ejection gradient ranged between 24 and 38 mm Hg and the valve area index between 0.71 and 1.15 cm²/m². Among 26 patients who underwent mitral valve replacement, 5 died operatively and 2 died 2 months postoperatively, leaving 19 long-term survivors who were followed up for 26.2 ± 15.6 months. In the 11 patients who underwent postoperative cardiac catheterization, the mean diastolic gradient was 6.1 ± 2.7 mm Hg and the mean valve index 1.79 ± 0.76 cm²/m². Severe subaortic obstruction, due to the prosthetic mitral valve, occurred in three of five patients less than 5 years old.Among four patients who underwent tricuspid valve replacement there were no operative deaths; complete heart block occurred in three. At postoperative catheterization in two patients, the mean diastolic gradient was 3 and 5 mm Hg, and the valve index 1.32 and 1.7 cm²/m², respectively. Three patients with I-transposition of the great arteries who underwent replacement of the systemic atrioventricular valve were followed up for 12 to 37 months. At postoperative catheterization the mean diastolic gradient was 0 to 4 mm Hg and the valve index ranged from 1.68 to 1.88 cm²/m². Both aortic and mitral valves were replaced in three children. One died at operation and one 6 months after operation. The survivor has complete heart block but is in New York Heart Association functional class I.Eight xenografts (6 mitral, 1 left atrioventricular valve in I-transposition of the great arteries and 1 aortic) failed, requiring replacement 22 to 68 months after implantation. All were calcified to varying degrees. Valve failure began presenting 22 months after implantation, and of 25 valves implanted for 20 months or longer, 8 have been replaced. These 8 patients were younger (10.3 ± 0.2 years) at initial valve replacement than the other 17 patients (15.0 ± 0.3 years) followed up for 20 months or longer (p <0.05). High levels of γ-carboxyglutamic acid (GLA), a calciumbinding amino acid, were found in all six calcified xenografts analyzed, whereas none was found in a fresh porcine aortic valve or in an unimplanted xenograft. GLA-containing protein, laid down after implantation, may play a role in xenograft calcification.     

Doppler Echocardiographic Assessment of the Bjork-Shiley Monostrut Valve Prosthesis in the Aortic Position

In order to determine the standard Doppler hemodynamic characteristics of the Bjork-Shiley monostrut aortic prosthesis and the value of the continuity equation to calculate the prosthetic valvular area, we performed Doppler echocardiographic study in 106 stable patients with this prosthesis and in 7 patients with suspicion of aortic Bjork-Shiley dysfunction. We measured maximum and mean Doppler gradients, prosthetic valvular area using the continuity equation, and degree of aortic regurgitation. The maximum and mean Doppler gradients in the 106 stable patients ranged from 9.5 to 51 mmHg (X?= 28.9 ± 11 mmHg) and from 2 to 24 mmHg (X?= 12.7 ± 5.2 mmHg), respectively. Maximum Doppler gradients > 45 mmHg and mean Doppler gradients > 20 mmHg occurred only in size 23 or smaller. No patient had a mean Doppler gradient > 25 mmHg. We found significant differences between sizes 25 and 27 (P < 0.01) and 21 and 25 (P < 0.01), but not between sizes 19, 21, and 23, or 23 and 25. There was significant difference in Doppler prosthetic valvular area between each valve size. The correlation coefficient between the prosthetic size and the echo-Doppler valvular area was 0.89 according to a lineal equation (SEE = 16). We could demonstrate mild aortic regurgitation in 25 cases (24%). The Doppler-derived prosthetic valvular area was < 0.38 cm² in two patients with obstruction and > 2 cm² in three patients with regurgitation alone. We conclude that high pressure gradients can be observed through the smallest sizes of the Bjork-Shiley monostrut aortic prostheses. Mild aortic regurgitation is a common finding. Our values are suggested as a reference for comparison in the case of suspected Bjork-Shiley valve dysfunction. The Doppler-derived prosthetic valvular area may be useful in patients with dysfunction of this prosthesis, especially to differentiate obstruction and regurgitation from regurgitation alone.     

Assessment of Left Atrial Pressure–Area Relation in Humans by Means of Retrograde Left Atrial Catheterization and Echocardiographic Automatic Boundary Detection: Effects of Dobutamine

Objectives. This study sought to validate and apply a new method for obtaining the left atrial (LA) pressure–area relation.Background. In physiologic investigations, the pressure–area relation is the most accurate and representative index of LA hemodynamic status.Methods. We applied real-time two-dimensional echocardiographic imaging with automatic boundary detection to estimate LA area changes. To obtain LA pressure, a catheter-tipped micromanometer was introduced retrogradely into the left atrium using a steerable cardiac catheter developed at our institution. Twenty-five patients (11 normal subjects, 7 patients with an enlarged left atrium due to heart failure, 7 patients with atrial fibrillation) were studied before and after dobutamine administration. From the LA pressure–area relation, the area of the A loop (the first counterclockwise loop) and the V loop (the second clockwise loop), the pressure–minimal area relation and the LA passive elastic chamber stiffness constant were measured.Results. Normalized pressure–minimal area relation was highly linear and sensitive to changes in inotropic state (normal subjects: from 0.96 to 1.27 mm Hg/cm², p < 0.01; patients with heart failure: from 0.59 to 0.68 mm Hg/cm², p = NS; patients with atrial fibrillation: from 0.80 to 1.06 mm Hg/cm², p < 0.05). The LA stroke work index was accurately calculated, and a very good correlation was found with LA preload. LA stroke work index was lower in patients with heart failure (3.9 ± 0.8 cm²·mm Hg, p < 0.001), whereas the LA stiffness constant was increased in patients with heart failure (0.801 ± 0.097 cm⁻², p < 0.01) and atrial fibrillation (0.796 ± 0.091 cm⁻², p < 0.01) compared with normal subjects (stroke work index 7.3 ± 1.9 cm²·mm Hg, stiffness constant 0.623 ± 0.107 cm⁻², respectively). In addition, increased inotropic state after dobutamine administration resulted in improved LA pump function (stroke work index) in normal subjects (from 10.2 ± 0.9 to 13.8 ± 1.9 cm²·mm Hg, p < 0.001) and patients with heart failure (from 4.3 ± 0.4 to 7.6 ± 0.4 cm²·mm Hg, p < 0.001), as well as in decreased stiffness constant in all groups of patients (normal subjects: from 0.712 ± 0.141 to 0.473 ± 0.089 cm⁻²; patients with heart failure: from 0.896 ± 0.181 to 0.494 ± 0.093 cm⁻²; patients with atrial fibrillation: from 0.779 ± 0.145 to 0.467 ± 0.086 cm⁻², p < 0.001).Conclusions. The method described here is both safe and reproducible for obtaining the LA pressure–area relation. LA function is impaired in patients with heart failure and in those with atrial fibrillation and may be acutely improved with inotropic agents in both normal and diseased atria.     

Hemodynamic assessment of the new aortic carpentier-edwards bioprosthesis

Although glutaraldehyde-preserved porcine aortic Hancock heterografts have lower thromboembolism incidence than mechanical aortic valves, Hancock xenografts provide less functional aortic outflow orifices and thereby greater transvalvular gradients than mechanical prostheses. The newly developed aortic Carpentier-Edwards porcine heterografts comprise a thin-walled Elgiloy flexible metal stent covered with Teflon which provides somewhat wider internal orifices than aortic Hancock valves of the same external annulus diameter. Since aortic Carpentier-Edwards xenografts have not been clincially evaluated previously, the present study assessed cardiac function and heterograft performance (1.7 months postoperation) and clinical status (4.2 months postoperation) of 19 patients with severe aortic stenosis and/or regurgitation prior to surgery. Left ventricular end-diastolic pressures decreased (17 to 9 mm Hg), cardiac index remained normal, and clincial symptomatology diminished markedly. Mean peak transxenograft systolic pressure was only 16 mm Hg (valve area 1.73 cm²), without meaningful regurgitation. Thus aortic Carpentier-Edwards bioprostheses provide generally excellent heterograft function which appears more favorable than previous reports of Hancock xenografts.     

Comprehensive Echocardiographic Assessment of Normal Transcatheter Valve Function

Objectives

This study aims to establish parameters for identifying normal function for each of the 3 iterations of balloon-expandable valves and 2 iterations of self-expanding valves.

Mid-term results of small-sized St. Jude Medical Regent prosthetic valves (21 mm or less) for small aortic annulus

Prosthesis–patient mismatch (PPM) is always of concern when performing aortic valve replacement (AVR) in patients with a small aortic annulus. Although bioprosthetic AVR is preferred in patients older than 65 years, we have experienced cases in elderly patients with a small aortic annulus whereby we could not implant small-sized bioprosthetic valves. We have implanted St. Jude Medical Regent (SJMR) mechanical valves (St. Jude Medical, St. Paul, MN, USA) as necessary, even in elderly patients with no aortic annulus enlargement. We investigated our experiences of AVR with SJMR mechanical valves of 21 mm or less in size. Between January 2006 and December 2009, 40 patients underwent AVR with SJMR mechanical valves ≤21 mm in size: 9 patients received 21-mm valves, 19 received 19-mm valves, and 12 received 17-mm valves. The mean age was 65.9 ± 9.5 years, and 25 patients (62.5 %) were 65 years or older. We evaluated the clinical outcome and the echocardiographic data for each valve size. There was no operative or hospital mortality. The mean duration of clinical follow-up was 31.2 ± 17.6 months. During follow-up, there were no hospitalizations due to heart failure. The cumulative valve-related event-free survival was 93 % at 33 months, and the cumulative hemorrhagic event-free survival was 93 % at 33 months and 84 % at 43 months, using the Kaplan–Meier method. At follow-up, the mean values of the measured effective orifice area (EOA) for the 21-, 19-, and 17-mm prostheses were 2.00 ± 0.22, 1.74 ± 0.37, and 1.25 ± 0.26 cm², and the mean measured EOA index (EOAI) were 1.17 ± 0.12, 1.11 ± 0.21 and 0.90 ± 0.22 cm²/m², respectively. A PPM (EOAI ≤0.85) was documented in 5 patients, all of whom had received a 17-mm SJMR valve. AVR with SJMR valves of 21 mm or less in size appears to show satisfactory clinical and hemodynamic results.     

An emergency physician's guide to prosthetic heart valves: identification and hemodynamic function

We describe methods for identifying the type and size of seven commonly used prosthetic heart valves and how these features influence the hemodynamics of flow through the valve. The four mechanical heart valves reviewed are Starr-Edwards silicone rubber ball valves (Models 1200/1260 aortic and 6120 mitral valves), Bjork-Shiley tilting disc valves (60 degrees standard spherical model and the 60 degrees convexo-concave model), Medtronic-Hall (Hall-Kaster) tilting disc valve, and St Jude Medical bileaflet valve. The three bioprostheses reviewed are Hancock porcine valve, Carpentier-Edwards porcine valve, and Ionescu-Shiley bovine pericardial valve. These valves were chosen because of their past or present popularity and therefore are the ones most apt to be implanted in patients seen in the emergency department.     

Effect of Transcatheter Aortic Valve Replacement on Right Ventricular–Pulmonary Artery Coupling

ObjectivesThe aim of this study was to test the hypothesis that the acute left ventricular (LV) unloading effect of transcatheter aortic valve replacement (TAVR) would improve right ventricular (RV) function and RV–pulmonary artery (PA) coupling in patients with severe aortic stenosis (AS).BackgroundRV dysfunction is an ominous prognostic marker in patients undergoing TAVR, suggesting that relief of obstruction might be less beneficial in this cohort. However, the left ventricle and right ventricle influence each other through ventricular interaction, which could lead to improved RV function through LV unloading.MethodsProspective invasive hemodynamic measurements with simultaneous echocardiography were performed in symptomatic patients with severe AS before and immediately after TAVR.ResultsForty-four patients (mean age 81 ± 8 years, 27% women) with severe AS underwent TAVR. At baseline, right atrial, PA mean (27 ± 7 mm Hg), and pulmonary capillary wedge (16 ± 4 mm Hg) pressures were mildly elevated, with a low normal cardiac index (2.3 l/min/m²). Pulmonary vascular resistance was mildly elevated (222 ± 133 dynes · s/cm⁵) and PA compliance mildly reduced (3.4 ± 01.4 ml/mm Hg). Following TAVR, aortic valve area increased (from 0.8 ± 0.3 to 2.7 ± 1.1 cm²; p < 0.001) with a reduction in mean aortic gradient (from 37 ± 11 to 7 ± 4 mm Hg; p < 0.001) and an increase in cardiac index (from 2.3 ± 0.5 to 2.5 ± 0.6 l/min/m²; p = 0.03). LV stroke work, end-systolic wall stress, and systolic ejection period decreased by 23% to 27% (p < 0.001 for all), indicating substantial LV unloading. RV stroke work (from 16 ± 7 to 18 ± 7 mm Hg · ml; p = 0.04) and tricuspid annular systolic velocities (from 9.5 ± 2.0 to 10.4 ± 3.5 cm/s; p = 0.01) increased, along with a decrease in PVR (194 ± 113 dynes · s/cm⁵; p = 0.03), indicating improvement in RV-PA coupling. Increased RV stroke work following TAVR directly correlated with the magnitude of increase in aortic valve area (r = 0.58; p < 0.001).ConclusionsAcute relief in obstruction to LV ejection with TAVR is associated with improvements in RV function and RV-PA coupling. These findings provide new insights into the potential benefits of LV unloading with TAVR on RV dysfunction in patients with severe AS.     

Doppler evaluation of the Sorin and Medtronic-Hall prostheses in the aortic position

Doppler characteristics of normally functioning tilting disk prostheses in aortic position were studied in 55 patients (30 Medtronic-Hall and 25 Sorin) whose valvular function was considered normal using clinical and echocardiographic evaluation. Peak gradients, mean gradients and effective orifice area were estimated for different sizes of prostheses. The peak gradient calculated from maximal aortic velocity was 27.3 +/- 11.1 mmHg in Sorin and 21.1 +/- 9.7 mmHg in Medtronic-Hall valves; the mean gradients were 12.9 +/- 6.2 mmHg and 10.8 +/- 5.7 mmHg in Sorin and Medtronic-Hall valves respectively. The effective orifice area calculated by the continuity equation was 1.4 +/- 0.5 cm2 in Sorin and 1.5 +/- 0.57 cm2 in Medtronic-Hall prostheses; the performance index calculated as the ratio between functional area and manufactured area was 0.4-0.6 for Medtronic-Hall and 0.45-0.52 for Sorin prostheses. Prosthetic regurgitation was found in 64% of Sorin valves and 80% of Medtronic-Hall valves; prosthetic regurgitation was mild in 81% and moderate in 19% of cases. Doppler echocardiography is a reliable method for the characterization of the normal function of prosthetic aortic valves and provides information similar to cardiac catheterization.     

A simple balloon-sizing method in Inoue-balloon percutaneous transvenous mitral commissurotomy

This study was carried out to examine whether the previously determined balloon sizing method based on patient height was valid for percutaneous transvenous mitral commissurotomy using the current second-generation Inoue balloon catheter. The study consisted of 70 patients with pliable noncalcified mitral valves (group 1) and 85 patients with calcified mitral valves and/or severe subvalvular lesions (group 2). The mitral valve area was increased more in group 1 than in group 2 (1.0 ± 0.3 to 1.9 ± 0.5 cm² versus 1.0 ± 0.3 to 1.6 ± 0.5 cm², P = 0.002). Using the stepwise dilatation technique, none of the group 1 patients developed severe mitral regurgitation. Severe mitral regurgitation occurred in 4 patients (4.7%) in group 2. In conclusion, a simple balloon sizing method based on body height for selection of an appropriate-sized balloon catheter, as well as an initial inflated balloon diameter for the stepwise dilatation technique is useful for optimal acute outcomes in mitral commissurotomy. © Wiley-Liss, Inc.     

Hemodynamic effects of nifedipine versus hydralazine in primary pulmonary hypertension

The acute hemodynamic effects of both sublingual nifedipine (N) and intravenous hydralazine (Hy) were studied in 5 patients with primary pulmonary hypertension to ascertain whether the capacity for pulmonary vasodilatation was generalized or drug-specific, and to determine which of the 2 agents had preferential pulmonary vasodilatory effects. For the group as a whole, neither N nor Hy produced changes in heart rate, mean pulmonary capillary wedge or right atrial pressures. Both N and Hy reduced mean systemic arterial pressure (before N 90 ± 8 mm Hg, after N 76 ± 7 mm Hg, p < 0.01; before Hy 92 ± 11 mm Hg, after Hy 68 ± 8 mm Hg, p < 0.05), and decreased systemic vascular resistance (before N 1,558 ± 645 dynes s cm^?5, after N 1,192 ± 430 dynes s cm^?5, p < 0.05; before Hy 1,700 ± 415 dynes s cm^?5, after Hy 957 ± 285 dynes s cm^?5, p < 0.05). In addition, N administration resulted in an increased cardiac output (before N 4.5 ± 2.0 liters/min, after N 4.8 ± 2.0 liters/min, p < 0.01); Hy administration was associated with a more varied effect on cardiac output (before Hy 4.0 ± 1.0 liters/min, after Hy 5.3 ± 1.8 liters/min, p < 0.10, difference not significant [NS]). Although for the group neither agent decreased mean pulmonary artery pressure (PAP) (before N 51 ± 13 mm Hg, after N 44 ± 13 mm Hg, NS; before Hy 50 ± 15 mm Hg, after Hy 51 ± 15 mm Hg, NS) or pulmonary vascular resistance (before N 873 ± 458 dynes s cm^?5, after N 680 ± 450 dynes s cm^?5, NS; before Hy 945 ± 454 dynes s cm^?5, after Hy 715 ± 309 dynes s cm^?5, NS), 4 of 5 patients had a decrease in PAP after N and 1 had no change, and only 1 of 5 patients had a decreased PAP after Hy administration. Moreover, compared with the changes after Hy administration, PAP declined after N administration (δPAP after Hy 0.2 ± 9 mm Hg, after N ?7 ± 9 mm Hg, p < 0.05). The PA diastolic to mean PA wedge pressure gradient tended to decrease after N administration (after N ?5.0 ± 10 mm Hg, after Hy +4.7 ± 7 mm Hg, NS), suggesting more pulmonary vasodilatation after N administration. Moreover, the ratio of pulmonary to systemic vascular resistances was unchanged after N but increased after Hy administration (before N 0.55 ± 0.2, after N 0.53 ± 0.2, NS; before Hy 0.55 ± 0.2, after Hy 0.74 ± 0.3, p < 0.02), indicating the more balanced vasodilatory effect of N. Two patients were treated chronically with Hy but had intolerable adverse effects; 1 was subsequently treated successfully with N. A third patient had pulmonary edema (presumably neurogenic) 30 minutes after Hy administration; this patient later died. Another patient has symptomatically improved with chronic N therapy. Thus, N appears to be a more specific pulmonary arterial vasodilator than Hy in acute drug testing; in this small group of patients with primary pulmonary hypertension, N appears to be more efficacious when administered chronically.     

Percutaneous mitral commissurotomy for severe mitral stenosis during pregnancy

Percutaneous mitral commissurotomy was performed in 27 pregnant females aged 24.9 ± 3.14 years (range 20–30 years) with severe mitral stenosis at 22.2 ± 4.3 weeks (range 18–32 weeks) of gestation. All patients were in New York Heart Association functional class IV at the time of procedure. The procedure was performed using the flow guided Inoue balloon in 25 patients and double balloon technique in 2 patients. Percutaneous mitral commissurotomy was successful in 26 patients. The mitral valve area assessed by Doppler echocardiography (pressure half time) increased from 0.78 ± 0.19 cm² (range 0.5–1.0 cm²) to 2.2 ± 0.12 cm² (range 1.9—2.6 cm²) (P <0.001). The mean mitral gradient decreased from 30.5 ± 7.6 mm Hg (range 22.5–41.4 mm Hg) to 6.1 ± 2.6 mm Hg (range 4.2–12.3 mm Hg) (P <0.001). The end diastolic gradient decreased from 28.3 ± 4.2 mm Hg (range 23–37 mm Hg) to 2.8 ± 1.5 mm Hg (range 0–5 mm Hg) (P <0.001). The total fluoroscopy time was 5.6 ± 2.2 min (range 2.7–8.9 min). Mitral regurgitation increased by one grade in 7 patients. One patient developed severe mitral regurgitation with anterior mitral leaflet tear needing immediate mitral valve replacement. Twenty-six patients improved to New York Heart Association class I after the procedure. Twenty-four patients had full-term, normal delivery and gave birth to healthy infants. The patients were followed up for 1–36 months (mean 16.6 ± 7.8 months). All patients were in New York Heart Association functional class I. No patient has shown any evidence of restenosis. The mitral valve area on follow-up was 2.1 ± 0.21 cm². The degree of mitral regurgitation remained unchanged. The results of this study indicate that percutaneous mitral commissurotomy is a safe and effective procedure for severe mitral stenosis in pregnancy. There are no immediate detrimental effects of radiation on the fetus, though long-term effects of this amount of radiation are yet to be ascertained. © Wiley-Liss, Inc.     

Valve Strain Quantitation in Normal Mitral Valves and Mitral Prolapse With Variable Degrees of Regurgitation

ObjectivesThe aim of this study was to quantitate patient-specific mitral valve (MV) strain in normal valves and in patients with mitral valve prolapse with and without significant mitral regurgitation (MR) and assess the determinants of MV strain.BackgroundFew data exist on MV deformation during systole in humans. Three-dimensional echocardiography allows for dynamic MV imaging, enabling digital modeling of MV function in health and disease.MethodsThree-dimensional transesophageal echocardiography was performed in 82 patients, 32 with normal MV and 50 with mitral valve prolapse (MVP): 12 with mild mitral regurgitation or less (MVP ? MR) and 38 with moderate MR or greater (MVP + MR). Three-dimensional MV models were generated, and the peak systolic strain of MV leaflets was computed on proprietary software.ResultsLeft ventricular ejection fraction was normal in all groups. MV annular dimensions were largest in MVP + MR (annular area: 13.8 ± 0.7 cm²) and comparable in MVP ? MR (10.6 ± 1 cm²) and normal valves (10.5 ± 0.3 cm²; analysis of variance: p < 0.001). Similarly, MV leaflet areas were largest in MVP + MR, particularly the posterior leaflet (8.7 ± 0.5 cm²); intermediate in MVP ? MR (6.5 ± 0.7 cm²); and smallest in normal valves (5.5 ± 0.2 cm²; p < 0.0001). Strain was overall highest in MVP + MR and lowest in normal valves. Patients with MVP ? MR had intermediate strain values that were higher than normal valves in the posterior leaflet (p = 0.001). On multivariable analysis, after adjustment for clinical and MV geometric parameters, leaflet thickness was the only parameter that was retained as being significantly correlated with mean MV strain (r = 0.34; p = 0.008).ConclusionsMVs that exhibit prolapse have higher strain compared to normal valves, particularly in the posterior leaflet. Although higher strain is observed with worsening MR and larger valves and annuli, mitral valve leaflet thickness—and, thus, underlying MV pathology—is the most significant independent determinant of valve deformation. Future studies are needed to assess the impact of MV strain determination on clinical outcome.     

Echocardiographic evaluation of Carpentier mitral valvuloplasty

Carpentier's technique for reconstructive mitral valve surgery is an alternative to mitral valve replacement in patients with mitral regurgitation. The procedure involves reconstruction of the mitral valve and insertion of a ring into the mitral anulus. To study the results of this operation, pre- and postoperative M-mode, two-dimensional (2DE), and Doppler echocardiography were performed on 13 patients with severe, symptomatic mitral regurgitation, who underwent reconstructive mitral surgery. A significant clinical improvement was noted in all patients. This correlated with the hemodynamic and angiographic improvement in six of the patients who underwent postoperative cardiac catheterization. Postoperative echocardiography showed that the mitral valve E-F slope decreased from 129 ± 30 mm/sec preoperatively to 53 ± 13 mm/sec postoperatively (p < 0.001). The mitral valve excursion decreased from 28 ± 6 mm preoperatively to 19 ± 2 mm postoperatively. The left ventricular minor axis shortening decreased from 32 ± 9% to 28 ± 6%. In seven patients the mitral valve area decreased from 4.5 ± 0.9 cm² to 2.8 ± 0.5 cm² (p < 0.005). In each patient a new echocardiographic finding was observed: two parallel dense linear echoes from the prosthetic ring were noted on M-mode echocardiogrphy near the base of the mitral valve. 2DE visualized the entire ring. Doppler echocardiography suggested moderate or severe mitral regurgitation in eight of eight patients studied preoperatively. Postoperatively 10 of 11 patients had no Doppler echocardiography finding of mitral regurgitation.     

Doppler echocardiographic evaluation of Hancock and Bj?rk-Shiley prosthetic values

Doppler echocardiographic characteristics of normally functioning Hancock and Bj?rk-Shiley prostheses in the mitral and aortic positions were studied in 50 patients whose valvular function was considered normal by clinical evaluation. Doppler studies were also performed in 46 patients with suspected malfunction of Hancock and Bj?rk-Shiley valves and who subsequently underwent cardiac catheterization. Mean gradients were estimated for both mitral and aortic valve prostheses and valve area was calculated for the mitral prostheses. Doppler prosthetic mitral valve gradient and valve area showed good correlation with values obtained with cardiac catheterization (r = 0.93 and 0.97, respectively) for both types of prosthetic valves. The correlation coefficient (r = 0.93) for mean prosthetic aortic valve gradient was also good, although Doppler echocardiography overestimated the mean gradient at lower degrees of obstruction. Regurgitation of Hancock and Bj?rk-Shiley prostheses in the mitral and aortic positions was correctly diagnosed. These results suggest that Doppler echocardiography is a reliable method for the characterization of normal and abnormal prosthetic valve function.     

Combined aortic and mitral balloon valvuloplasty in patients with critical aortic and mitral valve stenosis: Results in six cases

Six patients with severe combined aortic and mitral valve stenosis underwent double valve balloon dilation as an alternative to surgical valve replacement. Cardiac catheterization in all patients before valve dilation revealed heavily calcified aortic and mitral valves with severe stenosis and minimal regurgitation. Balloon aortic valvuloplasty was performed in each patient with a 20 mm balloon dilation catheter passed retrograde through the aortic valve whereas mitral valvuloplasty was performed transseptally with either a single or double balloon technique.After dilation, the mean aortic and mitral gradients decreased in all patients, with the area of the aortic and the mitral valve increasing from 0.5 ± 0.3 to 0.9 ± 0.3 cm²and from 0.7 ± 0.1 to 1.5 ± 0.7 cm², respectively. The procedures were well tolerated, with no embolic events and no significant increase in valvular regurgitation, and resulted in a reduction in symptoms of dyspnea on exertion and weakness in all patients that has persisted for an average of 5.7 months of follow-up in five of the six patients.It is concluded that combined dilation of stenotic aortic and mitral valves can be accomplished percutaneously and may be considered for patients with combined valvular stenosis who refuse or are deferred from surgical intervention.