Progress in mitral and aortic regurgitation

Over the past 15 years there has been rapid and dramatic change in the therapy for valvular heart disease. When mitral and aortic regurgitation are severe, they inevitably cause left ventricular damage, eventually resulting in death. However, when surgical correction of these lesions is timed appropriately, longevity can approach that of a normal population after surgery. As surgical techniques have improved, surgery is now indicated earlier in the course of these diseases. It is clear that some patients with mitral and aortic regurgitation require surgery even though they are entirely asymptomatic. However, it must be emphasized that mitral and aortic regurgitation are quite different from one another. These different lesions result in different loading conditions, different pathophysiologies, and have different means for surgical correction. All of these issues impact on the proper timing of surgery and are discussed. Copyright © 2001 by W.B. Saunders Company

Progress in Cardiovascular Diseases, Vol. 43, No. 6 (May/June) 2001: pp 457-475     

Combined mitral and aortic regurgitation in ankylosing spondylitis: Angiographic and anatomic features

Clinical and cardiac morphologic features are described in a man with combined aortic and mitral regurgitation associated with ankylosing spondylitis. Although aortic regurgitation is a recognized accompaniment of ankylosing spondylitis, the occurrence of hemodynamically-significant mitral regurgitation in this arthritic condition has not been documented previously. Histologic study disclosed changes in the anterior mitral leaflet identical to those observed in the wall of the aorta and base of the aortic valve cusps in patients with ankylosing spondylitis. Thus, ankylosing spondylitis may be associated with characteristic lesions in anterior mitral leaflet in addition to those in the ascending aorta and aortic valve. The subaortic bump at the base of the anterior mitral leaflet, the most characteristic cardiovascular lesion of ankylosing spondylitis, may be visualized during life by left ventricular angiography, and its identification allows proper etiologic diagnosis of the valvular regurgitation.     

Non-invasive assessment of aortic and mitral regurgitation

A non-invasive method for the assessment of the degree of regurgitationin aortic and mitral regurgitation is presented. Regurgitantvolume was obtained by subtracting effective stroke volume (SV_eff),determined with a CO₂-rebreathing method, from total strokevolume (SV_tot) determined by M-mode echocardiography. Regurgitantvolume and a non-invasive regurgitant index (SV_tot/SV_eff) werecompared with semiquantitative angiography in 49 patients [meanage = 62±11 (SD) years], who on the basis of the angiographywere allocated to four different groups (no, slight, moderateand severe regurgitation). Eighteen normal subjects [mean age= 26±9 (SD) years], not subjected to angiography, servedas a control group and are included in the group without regurgitation.When the cube formula was used for the determination of SV_tot,the average regurgitant volumes for the different groups were:0.5±24 (SD), 15±22, 85±48 and 138±65mland the corresponding SV_tot/SV_eff ratios were: 1.0±0.3,l.2±0.3, 2.4±0.8 and 3.8± 1.5, respectively.There were significant differences (P<0.01) between the groupswith slight, moderate and severe regurgitation respectivelyboth for regurgitant volume and regurgitant index, but no significantdifference between the group with slight regurgitation and thegroup without regurgitation. This study suggests that the severityof aortic and mitral regurgitation can be estimated non-invasivelyby the combined use of a CO2-rebreathing method and echocardiography.     

Preoperative left and right ventricular performance in combined aortic and mitral regurgitation and comparison with isolated aortic or mitral regurgitation

Left and right ventricular performance characteristics in operative candidates with combined aortic and mitral regurgitation (AR/MR) have not been well defined. Therefore, we determined radionuclide cineangiographic ejection fractions, as well as echocardiographic and hemodynamic parameters, in 8 symptomatic patients undergoing double-valve replacement with pure, severe AR/MR. In order to gain insight into the basis for the poor postoperative survival in patients with this intrinsically biventricular disease, we compared these results with those of 29 symptomatic patients with isolated AR and with 18 symptomatic patients with isolated MR, all also undergoing valve replacement. Before operation, patients with AR/MR had significantly lower left ventricular (LV) ejection fraction than patients with MR (rest, 40 +/- 9% vs 52 +/- 10%, p less than 0.025; exercise, 35 +/- 12% vs 54 +/- 12%, p less than 0.005) and tended to have lower LV ejection fraction than patients with AR alone (rest, 40 +/- 9% vs 45 +/- 12%, difference not significant; exercise, 35 +/- 12% vs 39 +/- 11%, difference not significant); right ventricular (RV) ejection fraction was lower in AR/MR than in AR (p less than 0.01), and tended to be lower than in MR (difference not significant). At average postoperative follow-up of 72 to 76 months (survivors in each group), symptomatic patients with AR/MR had significantly poorer survival than symptomatic patients with isolated MR (p less than 0.05) and were more likely to have persistent symptoms than patients with AR (p less than 0.05). These findings suggest that symptomatic patients with AR/MR have poorer LV and RV performance than similarly symptomatic operative candidates with AR or MR alone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Magnetic resonance assessment of aortic and mitral regurgitation

Magnetic resonance imaging provides an accurate method for the measurement of left and right ventricular volume. The ratio of left ventricular stroke volume to right ventricular stroke volume was calculated from contiguous transverse magnetic resonance images and was used to measure the severity of regurgitation in 18 patients with aortic regurgitation and 10 with mitral regurgitation. Cardiac anatomy was well demonstrated, allowing an assessment of relative chamber volumes and associated abnormalities, although valve abnormality was not well seen. There was a weak correlation between magnetic resonance measurements of left ventricular end diastolic volume and stroke volume ratio. The stroke volume ratio differed significantly in four groups with increasing angiographic severity of regurgitation, and all but the group with trivial regurgitation differed significantly from normal. There was good correlation between magnetic resonance and radionuclide measurements of left ventricular ejection fraction and stroke volume ratio, although the stroke volume ratio was consistently overestimated by radionuclide ventriculography. Correlation was less good for the right ventricular ejection fraction, which was underestimated by radionuclide ventriculography. It is concluded that magnetic resonance imaging provides valuable information in patients with valvar regurgitation, and serves as a suitable standard by which to judge conventional techniques.     

Vasodilator therapy for chronic aortic and mitral regurgitation

The use of vasodilator therapy in chronic AR and MR may be beneficial in selected patients and harmful in others. The hemodynamics of the two conditions are different and must be taken into account. In AR, vasodilators reduce afterload mismatch and can preserve LV function and delay the need for surgery. However, if the patient has severely reduced diastolic blood pressure, vasodilators could potentially impair coronary perfusion. In MR, vasodilators may reduce regurgitant volume and LV preload depending on the mechanism of MR. In patients with MR caused by dilated cardiomyopathy, vasodilators reduce symptoms, and improve functional class. However, in mitral valve prolapse or hypertrophic cardiomyopathy, vasodilators may worsen the MR and should be avoided. In other primary causes of MR, vasodilators could potentially mask the development of LV dysfunction and lead to unnecessary and harmful delays in surgery.     

Differences in left ventricular adaptation to chronic mitral and aortic regurgitation

For comparable volume load, impedance to ejection of the regurgitant volume in AR exceeds that in MR. To determine whether this load difference results in differences in PLVH and ejection performance, we studied consecutive, untreated, asymptomatic patients (11 in each group) by echocardiography and Doppler. Mean LVID, SBP, h, and FS were, respectively, in AR vs MR: 60.3 +/- 3.1 mm vs 62.0 +/- 2.3 mm (p = NS), 152 +/- 7.1 mm Hg vs 125 +/- 6.4 mm Hg (p less than 0.005), 12.1 +/- 0.4 mm vs 10.5 +/- 0.6 mm (p less than 0.04), and 0.38 +/- 0.02 vs 0.43 +/- 0.02 (p = NS). The h/R ratio reflects the PLVH-0.41 +/- 0.02 in AR and 0.34 +/- 0.02 in MR (p less than 0.02). The FS correlates positively with h/R in either lesion, but was higher in MR for any given h/R. The difference in loading conditions imposed by both lesions is associated with a difference in the PLVH as well as in ejection performance.     

Colour flow imaging in severe mitral and aortic regurgitation

Several criteria have been proposed for the grading of severe aortic and mitral regurgitation by colour flow imaging. To evaluate the sensitivity of these criteria, colour flow imaging was performed in 21 patients with isolated severe mitral regurgitation and 11 patients with isolated severe aortic regurgitation prior to clinically indicated valvular surgery. In the colour flow imaging assessment of mitral regurgitation the criterion of the maximum distance of mitral regurgitant jet from mitral orifice greater than 4.5 cm was 95% sensitive (range 4.4 to 8.4 cm). Maximum ratio of mitral regurgitant jet area to left atrial area greater than 40% was 86% sensitive (range 32 to 84%) and maximum mitral regurgitant jet area greater than 6 cm2 was 100% sensitive (range 8.1 to 35.7 cm2) in the detection of severe mitral regurgitation. For aortic regurgitation, the criterion of height of regurgitant jet to height of left ventricular outflow tract greater than 65% in the parasternal long axis view was 100% sensitive (range 71 to 100%), whereas the ratio of area of regurgitant jet to area of left ventricular outflow tract greater than 60% in the short axis view was only 36% sensitive (range 8 to 74%) in the detection of severe aortic regurgitation requiring surgery. It is concluded that the most sensitive colour flow imaging criteria for severe mitral regurgitation is an absolute mitral jet area greater than 8 cm2; and for severe aortic regurgitation, ratio of height of regurgitant jet to height of left ventricular outflow tract greater than 65%.     

Changes in mitral regurgitation after balloon aortic valvuloplasty

The coexistence of mitral regurgitation (MR) in patients with severe aortic stenosis (AS) is not infrequent and has been associated with adverse outcome. The aims of this study were to evaluate the change in MR severity and to identify the correlates of MR improvement in patients with severe AS and moderate to severe MR who underwent balloon aortic valvuloplasty (BAV). Patients with severe AS and at least moderate MR who underwent their first BAV procedures (n = 74) were divided into 2 groups: patients with improved- (n = 34 [46%]) and those without improved (n = 40 [54%]) MR after BAV on transthoracic echocardiography. The population had a mean age of 84 years and was more frequently female (63.5%), with a high risk profile (mean Society of Thoracic Surgeons score 15%, mean European System for Cardiac Operative Risk Evaluation score 57%). Baseline characteristics were balanced between the 2 groups. Patients with improved MR after BAV had smaller left atrial dimensions (45 ± 7 vs 49 ± 7 mm, p = 0.01) and lower peak aortic velocities (3.7 ± 0.6 vs 4.0 ± 0.8 m/s, p = 0.05) and mean transaortic valve gradients (33.2 ± 12.1 vs 40.6 ± 17.4 mm Hg, p = 0.05) at baseline. Left atrial dimension [odds ratio (OR) 3.37, p = 0.006], left ventricular end-diastolic dimension (OR 2.7, p = 0.04), and mean transaortic valve gradient (OR 1.04, p = 0.05), but not left ventricular systolic function or functional MR, were correlated with MR improvement by logistic regression analysis. In conclusion, nearly half of the patients with severe AS and coexistent MR showed improvement in the magnitude of MR after BAV. Larger left atrial and left ventricular end-diastolic dimensions and higher transaortic valve gradients were associated with lack of MR improvement.     

Magnetic resonance assessment of aortic and mitral regurgitation.

Magnetic resonance imaging provides an accurate method for the measurement of left and right ventricular volume. The ratio of left ventricular stroke volume to right ventricular stroke volume was calculated from contiguous transverse magnetic resonance images and was used to measure the severity of regurgitation in 18 patients with aortic regurgitation and 10 with mitral regurgitation. Cardiac anatomy was well demonstrated, allowing an assessment of relative chamber volumes and associated abnormalities, although valve abnormality was not well seen. There was a weak correlation between magnetic resonance measurements of left ventricular end diastolic volume and stroke volume ratio. The stroke volume ratio differed significantly in four groups with increasing angiographic severity of regurgitation, and all but the group with trivial regurgitation differed significantly from normal. There was good correlation between magnetic resonance and radionuclide measurements of left ventricular ejection fraction and stroke volume ratio, although the stroke volume ratio was consistently overestimated by radionuclide ventriculography. Correlation was less good for the right ventricular ejection fraction, which was underestimated by radionuclide ventriculography. It is concluded that magnetic resonance imaging provides valuable information in patients with valvar regurgitation, and serves as a suitable standard by which to judge conventional techniques.