Temporal response of left ventricular performance to mitral valve surgery

Disparate impact of severe aortic and mitral regurgitation on left ventricular dilation

In asymptomatic severe aortic (AR) and mitral regurgitation (MR), left ventricular (LV) dimension criteria were established to guide timing of valve replacement to prevent irreversible LV dysfunction. Given both lesions are primary LV volume overload ''leaks'', it might be expected that both lesions would induce similar impact on the LV and result in equivalent dimension criteria for intervention. However, the dimension-based intervention criteria for AR versus MR (developed through natural history studies), differ markedly. The pathophysiological foundations for such discordance have neither been fully elucidated nor emphasized. This case-based treatise compares the two regurgitant lesions with respect to: (a) ''total regurgitant circuits''; (b) ''driving pressures'' resulting in LV volume overload from each respective ''leak''; and (c) volume and afterload wall stresses imposed on the LV.Key points The ''total circuits'' of volume overload differ: The AR circuit includes the LV and systemic vasculature, whereas MR includes the LV ejecting into the left atrium/pulmonary veins and systemic circulation. The ''driving pressure'' of regurgitation and afterload are high with AR and low with MR. Differing ''total circuits'' and ''driving pressures'' impose disparate wall stresses upon the LV. Parallel and serial sarcomere replication occurs in AR, while only serial replication occurs in MR. It therefore follows that for regurgitation of similar severities, AR results in greater LV dilation at the point of irreversible myocardial dysfunction compared to MR. These considerations may explain, at least in part, the disparate dimension criteria employed for valve intervention for severe AR vs MR.

The most influential papers in mitral valve surgery; a bibliometric analysis

This study is an analysis of the 100 most cited articles in mitral valve surgery. A bibliometric analysis is a tool to evaluate research performance in a given field. It uses the number of times a publication is cited by others as a proxy marker of its impact. The most cited paper Carpentier et al. discusses mitral valve repair in terms of restoring the geometry of the entire valve rather than simply narrowing the annulus (Carpentier, J Thorac Cardiovasc Surg 86:23–37, 1983). The first successful mitral valve repair was performed by Elliot Cutler at Brigham and Women’s Hospital in 1923 (Cohn et al., Ann Cardiothorac Surg 4:315, 2015). More recently percutaneous and minimally invasive techniques that were originally designed as an option for high risk patients are being trialled in other patient groups (Hajar, Heart Views 19:160–3, 2018). Comparison of percutaneous method with open repair represents an expanding area of research (Hajar, Heart Views 19:160–3, 2018). This study will analyse the top 100 cited papers relevant to mitral valve surgery, identifying the most influential papers that guide current management, the institutions that produce them and the authors involved.

Antithrombotic Management of Patients With Prosthetic Heart Valves

Valvular heart disease is a major public health issue. The prevalence of valvular heart disease is expected to increase due to an aging population. Valve dysfunction manifests as valve stenosis, regurgitation, or both due to various etiologies. Valve repair and replacement are the main treatment options for severe valve dysfunction. Valve replacement is achieved by using either a mechanical or a bioprosthetic valve. Mechanical valves are more durable but require lifelong anticoagulation with associated complications. Bioprosthetic valves usually require anticoagulation only transiently after implantation but are less durable and degenerate more rapidly. In this article, we discuss antithrombotic regimens in persons after valve operations. We discuss general issues and antithrombotic recommendations for patients undergoing surgical bioprosthetic valve replacement, mechanical valve replacement (including different regimens for different positions and types of mechanical valves), mitral valve repair, and transcatheter aortic valve replacement. In addition, we discuss the antithrombotic management of patients in special circumstances, including patients with mechanical valves who have recurrent bleeding or thrombotic events, patients with mechanical valves undergoing surgery, and pregnant women with mechanical valves.

Mitral Valve Surgery for Dilated Cardiomyopathy with Mitral Regurgitation

Outcomes of surgery for non-ischemic non-valvular dilated cardiomyopathy with associated mitral regurgitation were assessed in 8 consecutive patients who underwent 9 mitral valve operations between 2001 and 2004. Mitral valve replacement was performed when the coaptation depth exceeded 10 mm. Two patients initially underwent mitral valvuloplasty, and 6 underwent valve replacement. One patient had valve replacement soon after valvuloplasty. Transthoracic echocardiography was performed immediately before surgery, before discharge, and during follow-up. Transesophageal echocardiography was carried out intraoperatively to assess valvular and ventricular function. Postoperative mean functional class was significantly better than the preoperative value (2.4 ± 0.7 vs. 3.3 ± 0.7), and the improvement was sustained during follow-up (2.0 ± 0.7). The ejection fraction and left ventricular end-diastolic dimension did not improve. One patient died without leaving hospital and two died during follow-up. The 2- and 4-year survival rates were 75.0% and 37.5%. Mitral valve surgery improved functional class without obvious changes in ejection fraction or left ventricular end-diastolic dimension.

Minimally invasive fibrillating mitral valve replacement for patients with advanced cardiomyopathy: a safe and effective approach to treat a complex problem

OBJECTIVE

The optimal management of mitral regurgitation (MR) in patients with cardiomyopathy has been controversial. Minimally invasive fibrillating mitral valve replacement (mini-MVR) might limit postoperative morbidity and mortality by minimizing recurrent MR. We hypothesized that mini-MVR with complete chordal sparing would offer low mortality and halt left ventricular (LV) remodeling in patients with severe cardiomyopathy and severe MR.

METHODS

From January 2006 to August 2009, 65 patients with an LV ejection fraction (LVEF) of ≤35% underwent mini-MVR. The demographic, echocardiographic, and clinical outcomes were analyzed.

RESULTS

The operative mortality compared with the Society of Thoracic Surgeons-predicted mortality was 6.2% versus 6.6%. It was 5.6% versus 7.4% for patients with an LVEF of ≤20% and 8.3% versus 17.9% among patients with a Society of Thoracic Surgeons-predicted mortality of ≥10%. At a median follow-up of 17 months, no recurrent MR or change in the LV dimensions or LVEF had developed, but the right ventricular systolic pressure had decreased (P=.02). At the first postoperative visit and latest follow-up visit, the New York Heart Association class had decreased from 3.0±0.6 to 1.7±0.7 and 2.0±1.0, respectively (P<.0001 for both). Patients with an LVEF of ≤20% and LV end-diastolic diameter of ≥6.5 cm were more likely to meet a composite of death, transplantation, or LV assist device insertion (P=.046).

CONCLUSIONS

Our results have shown that mini-MVR is safe in patients with advanced cardiomyopathy and resulted in no recurrent MR, stabilization of the LVEF and LV dimensions, and a decrease in right ventricular systolic pressure. This mini-MVR technique can be used to address severe MR in patients with advanced cardiomyopathy.

Early mitral valve surgery for chronic severe mitral regurgitation optimizes left ventricular performance and left ventricular mass regression

OBJECTIVE

The optimal timing of mitral valve surgery for severe mitral regurgitation is controversial. We aimed to evaluate the changes in left ventricular performance using ventricular energetics and left ventricular mass regression after the surgery to determine the appropriate surgical timing in asymptomatic patients with severe mitral regurgitation.

METHODS

Fifty consecutive asymptomatic or minimally symptomatic patients who electively underwent the surgery for severe mitral regurgitation were studied retrospectively. Contractility (end-systolic elastance), afterload (effective arterial elastance), and efficiency (ventriculoarterial coupling and ratio of stroke work to pressure-volume area), and left ventricular mass index were measured echocardiographically before and 1 month after surgery. Two-way repeated-measures analysis of variance was used to compare the parameters between patients with (n = 17) and without (n = 33) left ventricular dysfunction (ie, ejection fraction ≤60% and/or end-systolic dimension ≥40 mm).

RESULTS

Contractility did not change significantly (P = .94) but the afterload increased significantly (P < .0001) in both groups. Consequently, the efficiency deteriorated significantly (ventriculoarterial coupling, P = .0004; ratio of stroke work to pressure-volume area, P < .0001). Furthermore, the left ventricular mass index improved remarkably in both groups (P < .0001). Alternatively, the patients with normal left ventricular function had greater contractility (P < .0001), less worsened efficiency (P < .0001 and P < .0001, respectively), and a better left ventricular mass index (P = .0002) after surgery.

CONCLUSIONS

Early surgery for severe mitral regurgitation preserves left ventricular performance and improves left ventricular mass regression in asymptomatic patients with normal ventricular function.

Magnetic resonance imaging with 3-dimensional analysis of left ventricular remodeling in isolated mitral regurgitation: implications beyond dimensions

BACKGROUND

Although surgery is indicated in patients with mitral regurgitation (MR) when left ventricular (LV) end-systolic (LVES) dimension is >40 mm, LV ejection fraction may decrease after mitral valve surgery. We hypothesize that significant LV remodeling before surgery is not reflected by standard echocardiographic parameters measured at the base of the heart.

METHODS AND RESULTS

Ninety-four patients (age, 54 ± 11 years; 38% female) with degenerative isolated MR underwent cine magnetic resonance imaging with tissue tagging and 3-dimensional analysis. In 51 control subjects (age, 44 ± 14 years; 53% female), the relation between LVES volume (LVESV) and LVES dimension was quadratic, whereas in 94 MR patients, this relation was cubic, indicating a greater increase in LVESV per LVES dimension among MR patients. Moreover, magnetic resonance imaging LVESV from summated serial short-axis slices was significantly greater than LVESV assessed with the Bullet formula in MR patients, attributed to a more spherical remodeling distal to the tips of the papillary muscles (P<0.001). Thirty-five patients underwent mitral valve repair per current guideline recommendations. LV ejection fraction decreased from 61 ± 7% to 54 ± 8% (P<0.0001) and maximum shortening decreased significantly below normal at 1 year postoperatively (P<0.0001). Despite normalization of LV stroke volume and LV end-diastolic volume/mass ratio, there was a persistent significant increase in distal LVES 3-dimensional radius/wall thickness ratio and LVESV index after surgery.

CONCLUSIONS

Despite apparently preserved LVES dimension, MR patients demonstrate significant spherical mid to apical LVES remodeling that contributes to higher LVESV than predicted by standard geometry-based calculations. Decreased LV strain after surgery suggests that a volumetric analysis of LV remodeling and function may be preferred to evaluate disease progression in isolated MR.

Clinical and functional characterisation of rheumatic mitral regurgitation in children and adolescents including the brain natriuretic peptide

Rheumatic fever is a public health problem of universal distribution, predominantly affecting individuals in developing countries. In individuals less than 20 years of age, pure mitral regurgitation is the most commonly found condition in chronic rheumatic valve disease. In the present study, rheumatic mitral regurgitation was assessed in children and adolescents, addressing its clinical (duration of the disease, symptoms, use of benzathine penicillin, and number of outbreaks of the acute phase of rheumatic fever), electrocardiographic (left atrium abnormality and/or left ventricle hypertrophy) and echocardiographic characteristics (left atrium and ventricle measurements, ejection fraction and pulmonary artery pressure), as well as plasma dose of N-terminal portion of the brain natriuretic peptide through electrochemiluminescence immunoassay. Fifty-three patients were studied. The patients had moderate (41.5%) or severe (58.5%) rheumatic mitral regurgitation; had not undergone surgery; were not in the acute phase of the disease; and were being treated at a paediatric cardiology reference hospital in Northeastern Brazil. Mean patient age was 10.6 years (minimum of 3 and maximum of 19 years). With the exception of the ejection fraction, the echocardiographic variables had a significant correlation to the natriuretic peptide, demonstrating that this hormone reflects the haemodynamic consequences of mitral regurgitation. It was concluded that cardiac remodelling that occurs in rheumatic mitral regurgitation in children and adolescents leads to the production of the brain natriuretic peptide, which could be used as a complementary diagnostic tool in the follow-up of such patients.

Evaluation of Left Ventricular Contractile Function Using Noninvasively Determined Single-beat End-systolic Elastance in Mitral Regurgitation: Experimental Validation and Clinical Application

OBJECTIVE

We performed this study to validate the single-beat estimation of end-systolic elastance (E(es)) in an animal model of chronic mitral regurgitation (MR) and to use E(es) to predict postoperative left ventricular (LV) systolic function with the noninvasively derived single-beat E(es) (E(es-s)) in patients with MR.

METHODS

Eight sheep with MR were studied under 4 different loading conditions. E(es) was measured as the slope of the end-systolic pressure-volume relationship with a conductance catheter during inferior vena cava occlusion. E(es-s) was calculated using a bilinearly approximated time-varying elastance curve. We also studied 105 patients with MR who had undergone mitral valve repair. All measurements in these patients were performed before surgery and repeated at about 1 week after surgery.

RESULTS

In the animals in a total of 23 different stages, E(es-s) showed a good correlation and agreement with invasively determined E(es) (y = 0.84 x + 0.38; r = 0.8; P < .01, mean difference = 0.1 +/- 0.6 mm Hg/mL). In the clinical study, preoperative E(es-s) (r = 0.77; P < .001) and end-systolic volume index correlated well with postoperative ejection fraction (r = -0.69; P < .001). Multivariate analyses revealed that only E(es-s) was an independent predictor of postoperative LV function. Preoperative E(es-s) less than or equal to 1.0 mm Hg/mL was most predictive for identifying patients with LV dysfunction after surgery (sensitivity 87%; specificity 76%).

CONCLUSIONS

LV end-systolic elastance can be estimated noninvasively and is useful to detect latent LV dysfunction in patients with MR before surgery.

The management of functional mitral regurgitation

Mitral regurgitation (MR) may be classified into two major categories: primary and secondary (functional). In primary MR, disease of the valve itself (eg, myxomatous degeneration, rheumatic disease) causes valve incompetence, producing left ventricular (LV) volume overload. To compensate, the left ventricle must enlarge in order to increase its volume-pumping capacity. If volume overload is prolonged and severe, the adverse effects of remodeling together with activation of deleterious neurohumoral systems leads to myocardial damage. It is quite clear that correction of the volume overload causes myocardial healing and reverse remodeling. Conversely, in secondary MR, the valve itself is normal. Ventricular dilatation and wall motion abnormalities cause papillary muscle displacement and annular dilatation, causing a normal mitral valve to leak. In this situation it is not clear whether or when correction of the MR is beneficial because the MR was not the primary cause of the LV dysfunction to begin with. Other areas of uncertainty include the type of correction to be used and whether burgeoning technologies for percutaneous valve repair will be useful.

Preoperative Pulmonary Hypertension Is Associated with Postoperative Left Ventricular Dysfunction in Chronic Organic Mitral Regurgitation: An Echocardiographic and Hemodynamic Study

BACKGROUND

Some degree of pulmonary hypertension (PHTN) is common in patients with chronic mitral regurgitation. The aim of this study was to determine whether preoperative PHTN is associated with postoperative left ventricular (LV) dysfunction.

METHODS

The study included 79 patients with chronic organic mitral regurgitation. Preoperative and postoperative LV function was assessed by echocardiography. Preoperative and postoperative hemodynamics were evaluated by a pulmonary artery catheter.

RESULTS

Pulmonary artery systolic pressure decreased postoperatively (pre 49 +/- 14 vs. post 36 +/- 11 mm Hg, P < .01). Postoperative LV ejection fraction was significantly reduced in patients with preoperative PHTN (pre 61 +/- 11% vs post 49 +/- 12%, P < .01). A stepwise multivariate regression analysis showed that preoperative pulmonary artery systolic pressure and LV end-systolic dimension were independent predictors of postoperative LV ejection fraction (r = -0.53, P < .001, and r = -0.34, P < .05, respectively).

CONCLUSION

Preoperative PHTN is associated with postoperative LV dysfunction in patients with chronic organic mitral regurgitation undergoing mitral valve operation.

Anterior Leaflet Repair With Patch Augmentation for Mitral Regurgitation

BACKGROUND

Anterior leaflet repair continues to pose significant operative challenges, particularly in patients with retracted or "short" anterior leaflets, due to rheumatic or radiation induced mitral valve disease. This often results in abandonment of repair in favor of mitral valve replacement, requiring anticoagulation and altering left ventricular (LV) function and geometry. This study examines our experience of anterior leaflet repair with patch augmentation.

METHODS

Forty-two patients underwent mitral valve repair for a shortened anterior leaflet from 1994 to 2003. Twenty-two patients with a mean age of 53 +/- 6 years had radiation valvulitis (XR) whereas 20 patients, age 28 +/- 7 years had rheumatic heart disease (RHD). Those patients with XR had a mean New York Heart Association (NYHA) class of 3.2 +/- 0.4 and an angina score of 2.1 +/- 0.6 compared with a NYHA class 3.8 +/- 0.2 and no angina in RHD patients. All patients presented with severe MR. Anterior leaflet augmentation with a gluteraldehyde-treated, autologous pericardial patch and complete annuloplasty ring was used in all patients. Additionally, extensive subvalvar debridement was performed in RHD patients. Twelve XR patients underwent concomitant CABG with a mean of 2.4 +/- 0.8 grafts/patient. Additional surgical procedures included tricuspid valve repair, anterior septal defect, and aortic valve replacement. Mean follow-up was 39 +/- 10 months for XR patients and 12 +/- 25 months for RHD patients.

RESULTS

There were two late deaths in XR patients from underlying malignancies and no deaths in RHD patients. Two RHD patients required reoperation for recurrent mitral regurgitation at 3 and 20 months. All patients demonstrated clinical improvements (NYHA I-II) following repair. No mitral stenosis was induced.

CONCLUSIONS

Despite anterior leaflet shortening from XR or rheumatic alterations, opportunity still exists for gratifying mitral valve repair. By utilizing anterior leaflet patch augmentation, concomitantly with ring annuloplasty, anticoagulation is avoided, LV geometry is preserved, and follow-up reveals excellent functional improvement.

Évaluation de la fonction cardiaque en imagerie par résonance magnétique et scanner hélicoïdal multicoupe

Magnetic resonance imaging and multislice spiral computed tomography are ideal techniques for assessing cardiac function. The main objectives of this article are to describe the different aspects, global and regional systolic left ventricular function, diastolic left ventricular function and right ventricular function, and to introduce the agreed parameters for this evaluation.

Catheter-Based Approach to Mitral Regurgitation

Mitral Regurgitation (MR) is a common medical problem. MR is also a prognostic factor; patients with severe symptomatic MR have a poor prognosis with an annual mortality rate of 5% without surgical intervention. An anatomic understanding of the normal and regurgitant mitral valve is essential in order to evaluate appropriately the severity and impact of MR. We briefly discuss mitral complex anatomy, MR evaluation, and treatment options (surgical and catheter-based alternatives) according to the type of lesion found. In particular, our group has shown temporal percutaneous annuloplasty and definitive percutaneous edge-to-edge mitral valve repair to be a feasible technique. Recently a study evaluating endovascular mitral valve edge-to-edge repair was successfully initiated by our group. Acute and chronic ischemic mitral regurgitation and special situations, such as paravalvular leaks, hypertrophic obstructive cardiomyopathy, and mixed lesions are also discussed. Future directions may include the percutaneous transcatheter implantation of a bioprosthetic valve in mitral position.

Comparative Assessment of Chordal Preservation Versus Chordal Resection in Mitral Valve Replacement for Mitral Stenosis (Long-Term Follow-up: 8 Years)

Carrying out a mitral valve replacement (MVR) while preserving all chordae tendineae in patients with mitral regurgitation has been proven beneficial to the left ventricular performance. To evaluate the effectiveness of this technique in patients with mitral stenosis, a comparison of the echocardiographic data between patients who were operated on using this technique (Group Preservation = GroupP, n = 15), and those operated on using the conventional method of MVR (Group Conventional = GroupC, n = 15) was made. All patients were examined before surgery, 6 months after surgery and 8 years after surgery. The study population was limited to patients who had no evidence of coronary artery disease, aortic stenosis and/or regurgitation and patients who had pure mitral stenosis. Echocardiographic measurements obtained both 6 months and 8 years postoperatively revealed a significant decrease in the left ventricular ejection fraction in GroupC (61.33+/-9.29% preoperatively, 53.2+/-10.3% postoperatively). The difference between the decrease in the left ventricular ejection fraction of the two groups was statistically significant (-0.71+/-6.28% in GroupP, -8.07+/-13.35% in GroupC). There was no evidence of prosthetic valve dysfunction and no operative deaths. Two patients died in GroupP, 3 patients died in GroupC within the 8 year period. The conclusion was reached, that if suitable, mitral valve replacement while preserving the chordae tendineae is expected to have a beneficial effect on postoperative left ventricular performance in patients with mitral stenosis.

Blood flow in the left anterior descending coronary artery in children with ventricular septal defect

High-frequency echocardiography offers a noninvasive approach for imaging left anterior descending coronary artery (LAD) blood flow from a transthoracic window. The purpose of this study was to assess the effects of left ventricular (LV) volume overload on LAD flow in pediatric patients with ventricular septal defect (VSD). The study subjects consisted of 38 children with VSD and 15 healthy children. LV mass, LAD diameter, and LAD flow were measured by using transthoracic echocardiography, then LAD diameter and LV mass were indexed for body surface area. Pulmonary to systemic flow ratios (Qp/Qs) were obtained by cardiac catheterization. The Qp/Qs ratios ranged from 1.2 to 3.1 (mean 2.1 +/- 0.5). The mean LAD flow velocities, flow velocity integrals, and flow volumes were significantly higher in the patients than in the control subjects. LAD flow velocity and flow volume showed significant positive correlations with Qp/Qs, LV mass, and LV end-diastolic volume. Stepwise regression analysis revealed that Qp/Qs was the most important determinant of both LAD flow velocity (r(2) = 0.45, P < .0001) and LAD flow volume (r(2) = 0.44, P < .0001). The ratios of LAD flow volume to LV mass did not differ between the 2 groups. In 8 patients who underwent surgical treatment, LAD flow velocity, flow velocity integral, and flow volume decreased significantly after surgery. The current results suggest that patients with VSD have a higher resting coronary blood flow, and that LAD flow pattern is dependent on LV volume overload and changes after surgery.

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)

Randomized trial comparing partial versus complete chordal-sparing mitral valve replacement: effects on left ventricular volume and function

OBJECTIVE

The merits of retaining the subvalvular apparatus during mitral valve replacement for chronic mitral regurgitation have been demonstrated in numerous retrospective clinical investigations but not in a randomized study. In this report we analyzed the early and late effects of complete versus partial chordal preservation on left ventricular mechanics.

METHODS

Forty-seven patients undergoing isolated surgical correction of mitral insufficiency were prospectively randomized to either total or partial chordal-sparing mitral valve replacement. Complete data from 36 patients were available for analysis. Of these individuals, 15 had preservation of the posterior leaflet only (P-MVR group), and 21 had complete preservation of all chordal structures (C-MVR group). Echocardiography was performed preoperatively, at the time of discharge, and after 1 year to determine dimensions, wall stress, left ventricular mass, and ejection function.

RESULTS

End-diastolic volume decreased in both groups initially but continued to decline only in the C-MVR cohort. Similarly, although end-systolic volume decreased over time with total chordal preservation, no notable changes were observed in the P-MVR group. In the C-MVR group, end-systolic stress decreased initially but rose slightly by 1 year. In contrast, end-systolic stress remained unchanged at discharge in the P-MVR group and increased at 1 year. In terms of systolic performance, ejection fraction declined after surgical intervention with partial chordal-sparing techniques and did not improve by 1 year. Ejection fraction returned to the preoperative level after an initial decrease in the C-MVR group. Finally, left ventricular mass was reduced in the C-MVR cohort versus no change in the P-MVR group.

CONCLUSION

Complete retention of the mitral subvalvular apparatus during mitral valve replacement confers a significant early advantage by reducing left ventricular chamber size and systolic afterload compared with partial chordal preservation. Furthermore, left ventricular ejection performance continues to improve over time, probably because of more favorable left ventricular remodeling.

Surgical alternatives for heart failure

Heart failure is one of the leading causes of hospitalization in the United States. Congestive heart failure is a chronic, progressive disease and its central element is remodeling of the cardiac chamber associated with ventricular dilation. Secondary mitral regurgitation is a complication of end-stage cardiomyopathy and is associated with poor prognosis. Historically, these patients were not considered operative candidates because of their high morbidity and mortality. Heart transplantation is now considered standard treatment for select patients with end-stage heart disease; however, it is applicable only to a small number of patients. In an effort to address this problem, newer and alternative surgical approaches are evolving, including mitral valve annuloplasty, the Batista procedure, and other left ventricular shape changing technologies. Using these operative techniques to alter the shape of the left ventricle, in combination with optimal medical management for heart failure, improves survival, and patients may avoid or postpone transplantation.

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.

Normal myocardial function in severe right ventricular volume overload hypertrophy

Severe left ventricular volume overloading causes myocardial and cellular contractile dysfunction. Whether this is also true for severe right ventricular volume overloading was unknown. We therefore created severe tricuspid regurgitation percutaneously in seven dogs and then observed them for 3.5-4.0 yr. All five surviving operated dogs had severe tricuspid regurgitation and right heart failure, including massive ascites, but they did not have left heart failure. Right ventricular cardiocytes were isolated from these and from normal dogs, and sarcomere mechanics were assessed via laser diffraction. Right ventricular cardiocytes from the tricuspid regurgitation dogs were 20% longer than control cells, but neither the extent (0.171 +/- 0.005 microm) nor the velocity (2.92 +/- 0.12 microm/s) of sarcomere shortening differed from controls (0.179 +/- 0.005 microm and 3.09 +/- 0.11 microm/s, respectively). Thus, despite massive tricuspid regurgitation causing overt right heart failure, intrinsic right ventricular contractile function was normal. This finding for the severely volume-overloaded right ventricle stands in distinct contrast to our finding for the left ventricle severely volume overloaded by mitral regurgitation, wherein intrinsic contractile function is depressed.

Differences in left ventricular response between rheumatic and myxomatous mitral valve disease following mitral valve replacement

OBJECTIVE

We studied whether differences exist between hearts having rheumatic mitral valves and those having myxomatous mitral valves, in functional, geometrical, and mass changes in the left ventricle after mitral valve replacement.

METHODS

Patients who underwent mitral valve replacement without preservation of annular-papillary continuity for pure mitral incompetence were classified into rheumatic and myxomatous based on valvular histopathology. Echographic data measured before surgery was compared to that about 3 weeks after surgery.

RESULTS

In the rheumatic group, ejection fraction decreased from 57.5 +/- 10.8 to 47.7 +/- 12.0, indexed left ventricular internal dimension in systole (mm/m2) from 24.7 +/- 6.8 to 20.7 +/- 6.2 (P = 0.0001), and left ventricular mass index (g/m2) from 205 +/- 55 to 138 +/- 54 (P = 0.0002). In the myxomatous group, ejection fraction decreased from 60.4 +/- 11.6 to 39.7 +/- 14.5 (P = 0.0001), indexed left ventricular internal dimension in systole from 24.2 +/- 5.6 to 23.1 +/- 5.5, and left ventricular mass index from 195 +/- 83 to 111 +/- 72 (P = 0.0004). Mean wall thickness index and relative wall thickness showed significant differences between the two groups postoperatively but no significant difference preoperatively.

CONCLUSION

Hearts dilated due to chronic mitral incompetence respond differently after valvular replacement with total chordal excision depending on whether a rheumatic or myxomatous mitral valve is involved.

Mitral valve repair in heart failure

Mitral regurgitation (MR) is a frequent complication of end-stage heart failure. Historically, these patients were either managed medically or with mitral valve replacement, both associated with poor outcomes. Mitral valve repair via an 'undersized' annuloplasty repair is safe and effectively corrects MR in heart-failure patients. All of the observed changes contribute to reverse remodeling and restoration of the normal left-ventricular geometric relationship. Mitral valve repair offers a new strategy for patients with MR and end-stage heart failure.

A noninvasive method of measuring wave intensity, a new hemodynamic index: application to the carotid artery in patients with mitral regurgitation before and after surgery

Wave intensity (WI) is a new hemodynamic index, which is defined as (dP/dt)(dU/dt) at any site of the circulation, where dP/dt and dU/dt are the time derivatives of blood pressure and velocity, respectively. Arterial WI in normal subjects has two positive sharp peaks. The first peak occurs during early systole when a forward-traveling compression wave is generated by the left ventricle. The magnitude of this peak increases markedly with an increase in cardiac contractility. The second peak, which occurs towards the end of systole, is caused by generation of a forward-traveling expansion wave by the ability of the left ventricle to actively stop aortic blood flow. The interval between the R wave of the ECG and the first peak of WI (R-1st peak interval) and the interval between the first and second peaks (1st-2nd interval) are approximately equal to the preejection period and left ventricular ejection time, respectively. Using a combined Doppler and echo-tracking system, we obtained carotid arterial WI noninvasively. We examined the characteristics of WI in 11 patients with mitral regurgitation (MR) before and after surgery, and 24 normal volunteers. In the MR group before surgery, the second peak was decreased and the (1st-2nd interval)/(R-R interval) ratio was reduced, compared with the normal group (140 +/- 130 vs 750 +/- 290mmHg m/s3. P < 0.0083; 20.7% +/- 3.4% vs 26.7% +/- 2.8%, P < 0.083). There were no significant differences in the first peak between the normal group and the MR group before and after surgery. The second peak in the MR group was increased significantly (P < 0.016 vs before surgery) to 1,150 +/- 830mmHg m/s3 in the early period after surgery (stage I), and to 1,090 +/- 580mmHgm/s3 in the late period after surgery (stage II). These values did not differ significantly from that of the normal group. At stage I, the (R-1st peak interval)/ (R-R interval) ratio was increased from 13.4% +/- 2.7% to 20.6% +/- 5.6% (P < 0.016 vs before surgery). At stage II, this ratio decreased to 16.2% +/- 2.8% (P < 0.016 vs stage I). but was still significantly higher than that before surgery. The (1st-2nd interval)/(R-R interval) ratio increased significantly after surgery (P < 0.016 vs before surgery) to values (27.0% +/- 4.5% at stage I and 28.9% +/- 2.6% at stage II) which did not differ significantly from that of the normal group. The recovery of the second peak after surgery suggests that the left ventricle had recovered the ability to actively stop aortic blood flow. Wave intensity is useful for analyzing changes in the working condition of the heart.