Chronic Aortic and Mitral Regurgitation: Choosing the Optimal Time for Surgical Correction

Ten-year clinical laboratory follow-up after application of a symptom-based therapeutic strategy to patients with severe chronic aortic regurgitation of predominant rheumatic etiology

OBJECTIVES

This study was designed to assess the feasibility and the long-term results of a symptom-based strategy of aortic valve replacement in a Brazilian population with predominant rheumatic etiology.

BACKGROUND

Optimal criteria for valve replacement in aortic regurgitation (AR) are still not entirely clear. The appearance of symptoms is an indication for surgery, but may be associated with myocardial damage. Although cardiac imaging data have provided a safer guide for such decisions, the use of symptom-based surgical indication has not been validated and might conceivably be better in populations with predominant rheumatic etiology and younger age.

METHODS

Echocardiography and rest-exercise radionuclide ventriculography were performed in 75 patients with severe AR, age 28 +/- 9 years, over a period of 10 +/- 0.69 years. Thirty-seven patients developed symptoms and underwent aortic valve replacement surgery within six months. Thirty-eight patients remained asymptomatic and were managed medically.

RESULTS

Survival was 100% in asymptomatic patients and 82% in symptomatic. Surgical treatment caused marked ventricular remodeling, with ventricular diameter involution and an improvement of rest-exercise ejection fraction percent variation. Multivariate analysis showed that the probability of developing symptoms within 10 years was 58% for a patient with a left ventricular end-diastolic diameter > or =70 mm and 76% for a patient with left ventricular end-systolic (LVESD) > or =50 mm. Logistic regression identified LVESD and age as the most predictive and specific, but not sensitive, indicators of symptom development.

CONCLUSIONS

Application of a standardized therapeutic strategy to patients with severe AR and predominant rheumatic etiology resulted in 90.6% survival after 10 years of follow-up.

The significance of atrial fibrillation ablation in patients undergoing mitral valve surgery

Atrial fibrillation is present in close to 50% of all patients undergoing surgery for mitral valve disease.(1-3) However, surgical correction of atrial fibrillation in patients with other cardiac pathology that requires surgical intervention such as mitral valve disease was never considered as a standard approach. The Maze procedure for the treatment of atrial fibrillation was introduced in 1987 and was performed safely in hundreds of patients with excellent outcomes.(4-7) As a result, several centers have begun to combine the Maze procedure with other cardiac procedures, especially mitral valve surgery, without adding undue operative risk to patients.(8) When properly performed, the results with this combined approach have been excellent.(9,10)

Symptoms, left ventricular function, and timing of valve replacement surgery in patients with aortic regurgitation

BACKGROUND

Because cardiac decompensation is subtle, the best time to perform aortic valve replacement surgery may be difficult to determine. We investigated the relation of symptoms to left ventricular (LV) function and the timing of valve replacement in patients with aortic regurgitation (AR) of largely rheumatic origin.

METHODS

Sixty-eight initially asymptomatic patients (mean age 29 years) with severe chronic AR were monitored for 36 months. Assessments included baseline and yearly echocardiograms and radioisotope ventriculography (resting and exercise) and clinical examinations every 6 months.

RESULTS

Forty-seven patients (69%) remained asymptomatic and 21 (31%) had symptoms develop after 24 to 36 months. Compared with symptomatic patients, asymptomatic patients had significantly (P <.05) lower baseline LV end-diastolic diameter, end-systolic diameter, end-systolic stress, and volume/mass ratio but greater shortening fraction and ejection fraction (EF) at rest. These variables remained stable without statistically significant change until surgical correction in symptomatic patients. Percent variation of EF from rest to exercise increased in patients who remained asymptomatic (EF 2.8% +/- 10.6%) but decreased in those who became symptomatic (EF -4.2% +/- 13%; P <.05). Twenty symptomatic patients (New York Heart Association class III/IV, angina and/or syncope) had valve replacement surgery, after which all were in New York Heart Association class I/II and had significant decreases of LV end-diastolic and end-systolic diameters and an increase on percent variation of EF from rest to exercise (P <.0001).

CONCLUSIONS

Development of symptoms did not correlate with change in any ventricular function indexes. Surgery on appearance of symptoms restored LV function to near normal.

Preoperative cardiac preparation

Preoperative preparation of the cardiac patient is based on matching the cardiac reserve to the blood flow demands imposed by surgical stress and the underlying disease state. Evaluation must include functional assessment of any coronary artery disease or other organic cardiac disease that may place myocardial tissue at risk of ischemia as demand for cardiac output increases. Monitoring should be individualized based on anticipated problems and the risk assessment of the patient. Preoperative therapy should include maneuvers that reduce congestive heart failure, optimize volume status, and provide adequate cardiac output to deliver oxygen sufficient to meet or exceed demand. Underlying electrical and metabolic abnormalities should be corrected and controlled in the perioperative period. Long-term therapy should be evaluated and modified in the context of the anesthetic and surgical plan. Preventive interventions such as fluid loading and low-dose dopamine should be considered prior to surgery.

Integrated MR imaging approach to valvular heart disease

With development of cine and velocity encoded magnetic resonance imaging, it is now feasible to detect and quantify aortic and mitral stenosis and regurgitation accurately. In addition, magnetic resonance imaging has the capabilities to assess simultaneously left and right ventricular mass, volumes, and function precisely. The high accuracy and reproducibility of magnetic resonance imaging in quantification of regurgitation and ventricular function has the potential to provide improved monitoring of therapy and optimal timing of surgery in patients with valvular dysfunction. In comparison to echocardiography and angiography, some current limitations of magnetic resonance imaging to an integrated approach of valvular heart disease exist, which may be removed with future refinement of magnetic resonance imaging technology for cardiovascular imaging.

Left ventricular length-force-shortening relations before and after surgical correction of chronic mitral regurgitation

OBJECTIVES

We tested the hypothesis that postoperative left ventricular (LV) systolic wall stress can be predicted from the change in LV diastolic dimension and ejection fraction (EF) after surgical correction of chronic mitral regurgitation (MR). We used a simple mathematic model to predict postoperative systolic stress from end-diastolic dimension and EF. The validity of this model was assessed using data from 21 patients undergoing mitral valve replacement (MVR) for chronic MR.

BACKGROUND

The decline in EF after MVR for chronic MR is traditionally thought to be a consequence of a postoperative increase in afterload, caused by closure of a low resistance runoff into the left atrium. However, consideration of the Laplace relation suggests that afterload does not necessarily increase after the operation.

METHODS

A spherical mathematical model of the left ventricle was used to define the relations between LV end-diastolic dimension, systolic wall stress and EF. To test the validity of this model, clinical and echocardiographic data were obtained from 21 patients with chronic MR before and 10 to 14 days after MVR. These echocardiographic data were examined with reference to plots derived from the mathematical model.

RESULTS

Patients were categorized as those in whom end-diastolic dimension declined after the operation (group I, n = 15) and those with no reduction in end-diastolic dimension (group II, n = 6). Group I patients were subclassified into those undergoing MVR with chordal preservation (group Ia) and those undergoing MVR with chordal transection (group Ib). In groups Ib and II, there were significant reductions in EF (56 +/- 3% to 48 +/- 3% in group Ib and 50 +/- 2% to 40 +/- 3% in group II, both p < 0.05), but the changes in end-diastolic dimension and wall stress differed. In group Ib, end-diastolic dimension decreased and systolic wall stress was unchanged; in group II, end-diastolic dimension was unchanged and wall stress increased. In contrast, group Ia patients experienced a substantial reduction in end-diastolic dimension, no change in EF and a reduction in stress. The corresponding length-force-shortening coordinates closely approximate those predicted from a mathematic model relating end-diastolic dimension to EF and systolic wall stress.

CONCLUSIONS

Concordant echocardiographic and mathematical model results indicate that postoperative changes in systolic stress are directly related to changes in chamber size and that LV afterload may fall when chordal preservation techniques are used in combination with MVR.

Optimizing timing of surgical correction in patients with severe aortic regurgitation: role of symptoms

OBJECTIVES

We sought to determine the independent effect of preoperative symptoms on survival after surgical correction of aortic regurgitation (AR).

BACKGROUND

Aortic valve replacement for severe AR is recommended after New York Heart Association functional class III or IV symptoms develop. However, whether severe preoperative symptoms have a negative influence on postoperative survival remains controversial.

METHODS

Preoperative characteristics and postoperative survival in 161 patients with functional class I or II symptoms (group 1) were compared with those in 128 patients with class III or IV symptoms (group 2) undergoing surgical repair of severe isolated AR between 1980 and 1989.

RESULTS

Compared with group 1, group 2 patients were older (p < 0.0001), were more often female (p = 0.001) and more often had a history of hypertension (p = 0.001), diabetes mellitus (p = 0.029) or myocardial infarction (p = 0.005) and were more likely to require coronary artery bypass graft surgery (p < 0.0001). The operative mortality rate was higher in group 2 (7.8%) than in group 1 (1.2%, p = 0.005), and the 10-year postoperative survival rate was worse (45% +/- 5% [group 2] vs. 78% +/- 4% [group 1], p < 0.0001). Compared with age- and gender-matched control subjects, long-term postoperative survival was similar to that expected in group 1 (p = 0.14) but significantly worse in group 2 (p < 0.0001). On multivariate analysis, functional class III or IV symptoms were significant independent predictors of operative mortality (adjusted odds ratio 5.5, p = 0.036) and worse long-term postoperative survival (adjusted hazard ratio 1.81, p = 0.0091).

CONCLUSIONS

In the setting of severe AR, preoperative functional class III or IV symptoms are independent risk factors for excess immediate and long-term postoperative mortality. The presence of class II symptoms should be a strong incentive to consider immediate surgical correction of severe AR.

Recipient selection and management before cardiac transplantation

Cardiac transplantation is a proven, effective therapy for selected patients with end-stage congestive heart failure. Recipient selection is performed by a multidisciplinary team consisting of transplant physicians and surgeons. Clinicians responsible for patient assessment must establish the severity of cardiac dysfunction, formulate a prognosis, and stratify patients according to risk for mortality. Patients whose survival and quality of life are most limited without cardiac transplantation are candidates for therapy. The scarcity of organ donors makes careful screening of potential recipients necessary to identify those individuals most likely to obtain a long-term benefit. Recipient selection criteria and management strategies are evolving because of extended waiting times and high mortality caused by the lack of sufficient numbers of donors. Alternative therapies should be applied wherever possible.

Surgery for aortic regurgitation in women. Contrasting indications and outcomes compared with men

BACKGROUND

Indications for surgical correction of aortic regurgitation have been established mostly in men and have not been validated in women. The outcome of this surgical correction in women is unknown.

METHODS AND RESULTS

Baseline characteristics and postoperative outcomes were compared between 51 women and 198 men undergoing surgery for isolated aortic regurgitation between 1980 and 1989. Compared with men, women had surgery rarely for severe left ventricular enlargement (systolic diameter > or = 55 mm in 11% versus 27%, P = .031; diastolic diameter > or = 80 mm in 0% versus 16%, P < .0001) and more often for class III to IV symptoms (59% versus 32%, P < .0001). Operative mortalities were similar in women and men (3.9% and 4.5%, respectively). Among operative survivors, 10-year survival was worse for women than for men (39 +/- 9% versus 72 +/- 4%, P = .0002) and, in contrast with men, was worse than expected for women (P < .0001). Independent predictors of late survival were different for men (age and ejection fraction) and women (age and concomitant coronary bypass grafting). By multivariate analysis, female sex was an independent predictor of worse late survival (adjusted relative risk, 1.80; 95% CI, 1.04 to 3.11).

CONCLUSIONS

The generalization to women of the unadjusted left ventricular diameter surgical criteria established in men results in irrelevant criteria almost never reached in women, who often undergo surgery after developing severe symptoms. After surgery, women exhibit an excess late mortality, suggesting that surgical correction of aortic regurgitation should be considered at an earlier stage in women.

Importance of subvalvular preservation and early operation in mitral valve surgery

BACKGROUND

Mitral valve replacement (MVR) has a high mortality and morbidity. It has been suggested that preservation of the subvalvular apparatus and more optimal timing of surgery might improve outcome.

METHODS AND RESULTS

We performed a retrospective study of 612 consecutive patients who underwent mitral valve repair or replacement: 226 patients had repair, 68 had replacement with subvalvular preservation (MVR/SVP), and 318 had replacement without subvalvular preservation (MVR/NoSVP). Baseline characteristics were most unfavorable in the repair group with respect to age (P = .002) and in the repair and MVR/SVP groups with respect to NYHA functional class and left ventricular function (P = .044). Thirty-day mortality was lower in the repair (1.8%, P = .046) and MVR/SVP (1.5%. P = NS) groups than the MVR/NoSVP group (5.0%). Overall survival at 7 years was better in the repair (71.2 +/- 5.6%. P = .022) and MVR/SVP (66.2 +/- 12.4%, P = .017) groups than the MVR/NoSVP group (63.5 +/- 3.4%). Myocardial failure caused 66 of 107 complication-related deaths. Multivariate analysis confirmed independent beneficial effects of repair on 30-day mortality (odds ratio, 0.27, P < .05) and of repair and MVR/SVP on overall mortality (hazard ratios, 0.43, P < .001 and 0.40, P < .05, respectively) and complication-related death hazard ratios, 0.38, P < .001 and 0.35, P < .05, respectively). Preoperative NYHA class III or IV symptoms and left ventricular impairment were independent risk factors for death and myocardial failure.

CONCLUSIONS

Mitral valve repair is superior to replacement. If repair is not feasible, the subvalvular apparatus should be preserved. Early surgery before the development of severe symptoms and demonstrable left ventricular impairment is also needed to optimize outcome.

Aortic regurgitation complicated by extreme left ventricular dilation: long-term outcome after surgical correction

OBJECTIVES

This study sought to determine the outcome of aortic valve replacement for aortic regurgitation complicated by extreme left ventricular dilation.

BACKGROUND

Aortic valve replacement has been recommended in aortic regurgitation with extreme left ventricular dilation (diastolic dimension >/= 80 mm), but extreme left ventricular dilation raises concern about irreversible left ventricular dysfunction.

METHODS

Thirty-one patients with a preoperative echocardiographic diastolic dimension >/= 80 mm (group 1) undergoing operation for severe isolated aortic regurgitation between 1980 and 1989 were compared with 188 patients with a diastolic dimension <80 mm operated on during the same period (group 2).

RESULTS

Preoperatively, extreme left ventricular dilation was seen only in male patients and was associated with a reduced ejection fraction (43 +/- 12% vs. 53 +/- 11% [mean +/- SD], p < 0.0001). The postoperative outcome of group 1 was compared with that of male patients in group 2 (group 2M, n = 144). The operative mortality rates for groups 1 and 2M were 0% and 5.6%, respectively (p = 0.35). Late survival in operative survivors was similar in groups 1 and 2M, but compared with expected survival, an excess mortality was observed for group 1 (p = 0.024). Preoperative ejection fraction, but not diastolic dimension, independently predicted late survival and postoperative ejection fraction. Postoperatively, groups 1 and 2M showed a similar improvement in ejection fraction, but persistent left ventricular enlargement was more frequent in group 1.

CONCLUSIONS

Extreme left ventricular dilation due to aortic regurgitation is observed in male patients and is frequently associated preoperatively with a reduced ejection fraction but is not a marker of irreversible left ventricular dysfunction. Operative risk and late postoperative survival are acceptable in these patients, although a late excess mortality, predicted best by preoperative ejection fraction, is observed. Therefore, extreme left ventricular dilation is not a contraindication to operation, which should be performed before left ventricular dysfunction occurs.

New method for accurate calculation of regurgitant flow rate based on analysis of Doppler color flow maps of the proximal flow field. Validation in a canine model of mitral regurgitation with initial application in patients

OBJECTIVES

The purpose of this study was to develop a rational and objective method for selecting a region in the proximal flow field where the hemispheric formula for calculating regurgitant flow rates by the flow convergence technique is most accurate.

BACKGROUND

A major obstacle to clinical implementation of the proximal flow convergence method is that it assumes hemispheric isovelocity contours throughout the Doppler color flow map, whereas contour shape depends critically on location in the flow field.

METHODS

Twenty mitral regurgitant flow rate stages were produced in six dogs by implanting grommet orifices into the anterior mitral leaflet and varying driving pressures so that actual peak flow rate could be determined from the known effective regurgitant orifice times the orifice velocity. Because plotting flow rate calculated by using a hemispheric formula versus alias velocities produces underestimation near the orifice and overestimation far from it, this plot was fitted to a polynomial function to allow identification of an inflection point within a relatively flat intermediate zone, where factors causing overestimation and underestimation are expected to be unimportant or balanced. The accuracy of flow rate calculation by the inflection point was compared with unselective and selective averaging techniques. Clinical relevance, initial feasibility and correlation with an independent measure were tested in 13 consecutive patients with mitral regurgitation who underwent cardiac catheterization.

RESULTS

1) The accuracy of single-point calculations was improved by selecting points in the flat portion of the curve (y = 1.15x - 3.34, r = 0.87, SEE = 22.1 ml/s vs. y = 1.34x - 1.99, r = 0.71, SEE = 45.6 ml/s, p < 0.01). 2) Selective averaging of points in the flat portion of the curve further improved accuracy and decreased scatter compared with unselective averaging (y = 1.08x + 4.8, r = 0.96, SEE = 11.6 ml/s vs. y = 1.30x + 0.6, r = 0.90, SEE = 20.9 ml/s, p < 0.01). 3) The proposed algorithm for mathematically identifying the inflection point provided the best results (y = 0.96x + 4.5, r = 0.96, SEE = 9.9 ml/s), with a mean error of 1.6 +/- 9.7 ml/s vs. 11.4 +/- 11.7 ml/s for selective averaging (p < 0.01). In patients, the proposed algorithm identified an inflection point at which calculated regurgitant volume agreed best with invasive measurements (y = 1.1x - 0.61, r = 0.93, SEE = 17 ml).

CONCLUSIONS

The accuracy of the proximal flow convergence method can be significantly improved by analyzing the flow field mathematically to identify the optimal isovelocity zone before using the hemispheric formula to calculate regurgitant flow rates. Because the proposed algorithm is objective, operator independent and, thus, suitable for automatization, it could provide the clinician with a powerful quantitative tool to assess valvular regurgitation.

Selection and treatment of candidates for heart transplantation. A statement for health professionals from the Committee on Heart Failure and Cardiac Transplantation of the Council on Clinical Cardiology, American Heart Association

Improved outcome of heart failure in response to medical therapy, coupled with a critical shortage of donor organs, makes it imperative to restrict heart transplantation to patients who are most disabled by heart failure and who are likely to derive the maximum benefit from transplantation. Hemodynamic and functional indexes of prognosis are helpful in identifying these patients. Stratification of ambulatory heart failure patients by objective criteria, such as peak exercise oxygen consumption, has improved ability to select appropriate adult patients for heart transplantation. Such patients will have a poor prognosis despite optimal medical therapy. When determining the impact of individual comorbid conditions on a patient's candidacy for heart transplantation, the detrimental effects of each condition on posttransplantation outcome should be weighed. Evaluation of patients with severe heart failure should be done by a multidisciplinary team that is expert in management of heart failure, performance of cardiac surgery in patients with low left ventricular ejection fraction, and transplantation. Potential heart transplant candidates should be reevaluated on a regular basis to assess continued need for transplantation. Long-term management of heart failure should include continuity of care by an experienced physician, optimal dosing in conventional therapy, and periodic reevaluation of left ventricular function and exercise capacity. The outcome of high-risk conventional cardiovascular surgery should be weighed against that of transplantation in patients with ischemic and valvular heart disease. Establishment of regional specialized heart failure centers may improve access to optimal medical therapy and new promising medical and surgical treatments for these patients as well as stimulate investigative efforts to accelerate progress in this critical area.

Proximal jet size by Doppler color flow mapping predicts severity of mitral regurgitation. Clinical studies

BACKGROUND

Recent studies have shown that many instrument and physiological factors limit the ability of color Doppler total jet area within the receiving chamber to predict the severity of valvular regurgitation. In contrast, the proximal or initial dimensions of the jet as it emerges from the orifice have been shown to increase directly with orifice size and to correlate well with the severity of aortic insufficiency. Only limited data, however, are available regarding the value of proximal jet size in mitral regurgitation, and it has not been examined in short-axis or transthoracic views. The purpose of the present study, therefore, was to evaluate the relation between proximal jet size and other measures of the severity of mitral regurgitation.

METHODS AND RESULTS

In 49 patients, the anteroposterior height of the proximal jet as it emerges from the mitral valve was measured in the parasternal long-axis view; proximal jet width and area were measured in the short-axis view at the same level. Results were compared with regurgitant volume and fraction by pulsed Doppler subtraction of aortic and mitral flows in 47 patients without more than trace aortic insufficiency; with angiographic grade determined within 24 hours in 33 catheterized patients; and with angiographic regurgitant fraction in 13 patients who were in normal sinus rhythm and had no significant aortic and tricuspid insufficiency. Proximal jet height, width, and area correlated well with Doppler regurgitant volume and fraction (r = .86 to .95; SEE = 7.7 to 9.0 mL; 5.9% to 7.3%). Proximal jet size could also be used to distinguish angiographic grades of mitral regurgitation with minimal overlap (P < .0001) and correlated well with angiographic regurgitant fraction (r = .85 to .91; SEE = 4.1% to 5.1%).

CONCLUSIONS

Proximal jet size correlates well with established measures of the severity of mitral regurgitation. It is conveniently available with transthoracic clinical scanning and should be useful in the routine evaluation of patients with mitral regurgitation.

Surgical timing in aortic regurgitation: left ventricular function analysis by contractility score

In 32 patients with aortic regurgitation, angiographic evaluation of global left ventricular performance before and after aortic valve replacement was carried out by means of a computer-analyzed contractility scoring system. A strong correlation was detected between the preoperative and postoperative contractility score. Postoperatively, the score decreased in all but 3 patients, becoming normal or near normal in 21 of 27 patients whose preoperative value had been less than 40. However, all 5 patients with a preoperative contractility score of 40 or greater exhibited a persistently elevated score after operation that indicated the presence of irreversible contractile dysfunction. Patients in groups A and B (preoperative score, 0 to 40) experienced a good surgical outcome, and at 5-year follow-up were in New York Heart Association functional class I. Patients in group C (preoperative score, > 40) altogether had a very poor surgical outcome, although they did experience a short to midterm period of symptomatic relief. It is important to offer aortic valve replacement to patients with aortic regurgitation before their chances for a good functional result are lost. The computer-analyzed contractility score may be a useful index for determining the optimal timing of operation in these patients, particularly those who show features consistent with impaired left ventricular function but are asymptomatic and who should undergo aortic valve replacement before symptoms of definitive left ventricular failure develop.

Aortic regurgitation. Identifying and treating acute and chronic disease

Aortic regurgitation is a serious disorder that can challenge the best clinicians in terms of both diagnosis and management. The chronic form requires valve replacement when patients have symptoms or show evidence of left ventricular dysfunction. The acute form requires urgent aortic valve replacement. In all cases, medical management is only a temporizing procedure that can potentially mask the progression of left ventricular dysfunction. Endocarditis prophylaxis for indicated procedures is mandatory for all patients.

Changes in diastolic function during development and correction of chronic LV volume overload produced by mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) causes an augmentation in left ventricular (LV) diastolic function, increasing early diastolic filling rate and decreasing LV stiffness. Whether these changes in diastolic function persist, return to normal, or become abnormal after mitral valve replacement (MVR) is unknown.

METHODS AND RESULTS

Simultaneous LV echocardiography and catheterization studies were performed in six dogs in the baseline state (baseline), 3 months after creation of MR (chronic MR), and 3 months after MVR. Chronic MR caused LV dilation (end-diastolic dimension increased from 4.5 +/- 0.1 cm in baseline to 5.8 +/- 0.1 cm in chronic MR, p < 0.05) and eccentric LV hypertrophy (LV-to-body weight ratio increased from 3.6 +/- 0.2 g/kg in baseline to 4.9 +/- 0.4 g/kg in chronic MR, p < 0.05). Chronic MR caused an increase in LV early diastolic filling rate (peak rate of increase in minor-axis dimension increased from 11 +/- 1 cm/sec in baseline to 18 +/- 1 cm/sec in chronic MR, p < 0.05), did not change the time constant of myocardial relaxation (tau was 31 +/- 4 msec in baseline and 30 +/- 2 msec in chronic MR), and caused a decrease in the modulus of regional chamber stiffness from 7.7 +/- 1.2 in baseline to 2.4 +/- 0.03 in chronic MR, p < 0.05. MVR caused the resolution of LV dilation (end-diastolic dimension returned to normal [4.8 +/- 0.2 cm]), but three months after MVR, regression of LV hypertrophy was incomplete (LV-to-body weight ratio remained elevated [4.4 +/- 0.5 g/kg]). After MVR, LV early diastolic filling rate (8 +/- 1 cm/sec), the relaxation time constant (31 +/- 2 msec), chamber stiffness (7.1 +/- 1.8), myocardial stiffness (11.2 +/- 3.1), and LV end-diastolic pressure (8 +/- 1 mm Hg) returned to normal.

CONCLUSIONS

The enhanced diastolic function seen in chronic MR returned to normal after correction of the chronic volume overload by MVR.

The changing unnatural history of valvular regurgitation

In the past 15 years three major advancements have improved the lot of our patients with left-sided valvular regurgitation. First, the concept that mitral and aortic regurgitation were similar volume overloading lesions has changed. Mitral regurgitation constitutes a nearly pure volume overload wherein the excess volume is ejected against relatively low pressure into the left atrium. On the other hand, aortic regurgitation represents a combined pressure and volume overload in which the excess volume being pumped is ejected against the relatively high pressure of the aorta. These differences in loading between mitral and aortic regurgitation produce a different response to operation. Afterload reduction after correction of aortic regurgitation increases ejection performance if it was decreased preoperatively. Conversely, afterload increases after mitral valve replacement, decreasing ejection performance. These differences make the left ventricle in mitral regurgitation less tolerant of preoperative dysfunction than the left ventricle in aortic regurgitation. Second, with respect to aortic regurgitation, reproducible indexes have been developed that identify when left ventricular dysfunction is present, leading to earlier operation in an attempt to avoid permanent ventricular dysfunction. In turn, earlier operation has led to a fall in operative mortality rate and an almost universal increase in left ventricular function if it was depressed preoperatively. Third, with regard to mitral regurgitation, recognition of the importance of the mitral valve apparatus in maintaining left ventricular function has led to an increased emphasis on chordal preservation during mitral valve operations.(ABSTRACT TRUNCATED AT 250 WORDS)