Techniques and results of mitral valve repair for ischemic mitral regurgitation

Case report: necrosis of the anterolateral papillary muscle--an unusual mechanical complication of myocardial infarction

We report the case of a 66-year-old woman with no significant past medical history who presented to the Emergency Department at Houston Methodist Hospital with 24 hours of chest pain. An electrocardiogram was done, an electrocardiogram confirmed a posterolateral ST elevation myocardial infarction. An immediate and successful percutaneous coronary intervention of a totally occluded ramus intermedius was performed. Six hours later she developed pulmonary edema, cardiogenic shock, severe acidosis, and anuria. Echocardiography showed severe mitral regurgitation due to a ruptured anterolateral papillary muscle, and emergency surgery revealed necrosis of this muscle. A bioprosthetic mitral valve was placed, and extracorporeal membrane oxygenation was needed for 3 days. This is a rare mechanical complication of myocardial infarction, which usually affects the posteromedial papillary muscle. The patient subsequently made a good recovery. One month later, just prior to discharge home, the patient developed pneumonia and sepsis, and she expired from multiorgan failure.

A forgotten devil; Rupture of mitral valve papillary muscle

Background:

Papillary muscle rupture is one of the catastrophic mechanical complications following myocardial infarction. Rupture leads to acute mitral valve regurgitation, pulmonary edema, and cardiogenic shock. Survival is dependent on prompt recognition and surgical intervention.

Cases Report:

We present two cases where acute myocardial infarction was complicated by papillary muscle rupture resulting in severe mitral regurgitation and cardiogenic shock. In both cases rupture occurred within one week of infarction. Both patients did not receive coronary revascularization; one patient presented late after the onset of chest pain, the other patient percutaneous revascularization attempted and was not successful. Both patients suffered an inferior wall infarction. Echocardiogram demonstrated severe mitral regurgitation with a jet directed posteriorly. In both cases rupture of the posteromedial papillary muscle resulted in flail of the anterior mitral valve leaflet, thus serving as a reminder that both the anterior and the posterior leaflets attach to both papillary muscles.

Conclusions:

While one case had a good outcome, the other reinforces the fact that this is a very serious complication requiring prompt recognition and treatment.

Influence of patient age on procedural selection in mitral valve surgery

BACKGROUND

Previous studies suggest that mitral valve replacement is comparable to repair in the elderly, and a national trend exists toward tissue valves. However, few direct comparison data are available, and this study evaluated the effects of patient age on risk-adjusted survival after mitral procedures.

METHODS

From 1986 to 2006, 2,064 patients underwent isolated primary mitral operations (±CABG). Maximal follow-up was 20 years with a median of 5 years. Valve disease etiology was the following: degenerative, 864; ischemic, 450; rheumatic, 416; endocarditis, 98; and "other," 236. Overall, 58% had repair and 39% had concomitant coronary artery bypass grafting. Survival differences were evaluated with a Cox proportional hazards model that included baseline characteristics, valve disease etiology, and choice of repair versus replacement with tissue or mechanical valves.

RESULTS

Baseline risk profiles generally were better for mechanical valves, and age was the most significant multivariable predictor of late mortality [hazard ratio = 1.4 per 10-year increment, Wald χ(2) = 32.7, p < 0.0001]. As compared with repair, risk-adjusted survival was inferior with either tissue valves [1.8, 27.6, <0.0001] or mechanical valves [1.3, 8.1, 0.0044], and no treatment interaction was observed with age (p = 0.18). At no patient age did tissue valves achieve equivalent survival to either repair or mechanical valves.

CONCLUSIONS

Mitral repair is associated with better survival than valve replacement across the spectrum of patient age. If replacement is required, mechanical valves achieve better outcomes, even in the elderly. These data suggest that tissue valves should be reserved only for patients with absolute contraindications to anticoagulation who are not amenable to repair.

Echocardiographic evaluation of systolic heart failure

Echocardiography is the most commonly used modality for evaluating left ventricular size and function in the context of systolic heart failure. Traditional techniques, though extensively used, have their limitations and more recently several newer technologies have emerged that are more reproducible, provide prognostic information, guide therapies and have an important role in monitoring progress. This review will evaluate the traditional and more novel techniques used and briefly provide an overview of the role of echocardiography in guiding and monitoring therapies in patients with systolic heart failure.

Mitral valve repair versus revascularization alone in the treatment of ischemic mitral regurgitation

BACKGROUND

For patients with ischemic mitral regurgitation (MR), it is not clear whether adjunctive mitral valve (MV) repair at the time of coronary artery bypass graft surgery (CABG) is beneficial. We sought to test the hypothesis that MV repair with CABG is superior to CABG alone in improving MR without increasing operative or long-term mortality.

METHODS AND RESULTS

A total of 107 consecutive patients with moderate or severe ischemic MR, as determined by preoperative echocardiography, underwent CABG with concomitant MV repair (repair group, n=50) or CABG only (CABG group, n=57). Degree of MR was graded as none, mild, moderate, or severe by the proximal isovelocity surface area method. The groups were similar with respect to age, gender, baseline New York Heart Association class, ejection fraction, and number of bypass grafts. The repair group had a higher percentage of patients with atrial fibrillation or severe MR than the CABG group. The operative mortality was significantly higher for the repair group (12%) than the CABG group (2%), whereas the 5-year actuarial survival rate of the 2 groups was similar (88%+/-5% versus 87%+/-6%). On multivariate logistic regression analysis, older age, higher New York Heart Association class, and atrial fibrillation were independent predictors of operative mortality (P<0.05). Among patients with severe MR, ischemic MR was improved in all patients of the repair group and in 67% of patients in the CABG group (P<0.001), whereas improvement rates in patients with moderate MR were similar in the 2 groups (75% versus 67%, P=NS).

CONCLUSIONS

Although MV repair appears to be more effective at reducing ischemic functional MR, CABG alone may be a preferable treatment option for patients with moderate MR and high operative risk factors such as old age or atrial fibrillation.

Ischemic mitral regurgitation: revascularization alone versus revascularization and mitral valve repair

BACKGROUND

In this study we compared the surgical management of ischemic mitral regurgitation (IMR) by revascularization alone and by revascularization combined with mitral valve repair.

METHODS

We studied 355 patients who underwent revascularization alone (n = 168) or revascularization combined with mitral valve repair (n = 187) for IMR from March 1994 to September 2003. Preoperative and operative characteristics, postoperative mitral regurgitation severity, operative mortality, and late survival were examined for each surgical group.

RESULTS

No differences were noted between the two groups in age, sex, history of diabetes or hypertension, and number of bypass grafts. The combined surgical group had a lower preoperative left ventricular ejection fraction (0.38 +/- 0.14 versus 0.44 +/- 0.15), greater severity of IMR, higher frequency of prior myocardial infarction, and longer cross-clamp and pump times (p < 0.01). The combined surgical group had a greater reduction in IMR grade (2.7 +/- 0.1 grades versus 0.2 +/- 0.1 grade), a lower postoperative IMR grade (0.9 +/- 0.1 versus 2.3 +/- 0.1), and a higher success with reduction of IMR by two or more grades (89% versus 11%) (p < 0.001). In patients with 3+ or 4+ IMR, both groups had similar operative mortality (11.0% in the combined group compared with 4.7% for revascularization alone, p = 0.11) and actuarial survival at 5 years (44% +/- 5% versus 41% +/- 7%, p = 0.53). Independently predictive of higher early mortality (< or = 30 days) by Cox analysis were longer pump time (p < 0.001) and older age (p < 0.02). Predictive of late mortality (> 30 days) were older age (p < 0.001), fewer bypass grafts (p < 0.01), and lower ejection fraction (p < 0.01). After adjustment for these variables, there was a trend (p = 0.08) toward a higher late survival with the combined surgical procedure.

CONCLUSIONS

In patients with IMR, combined mitral valve repair and revascularization resulted in less postoperative mitral regurgitation and similar 5-year survival when compared with revascularization alone. Attempts to reduce pump time by using off-pump techniques may reduce early mortality in these high-risk patients.

Ischemic mitral valve repair: correlations between the mechanisms of mitral regurgitation and left ventricular function prior to and following surgery

OBJECTIVE

To define the mechanisms of ischemic mitral regurgitation (MR) and its correlation with left ventricular (LV) function prior to and 1 year following mitral valve (MV) repair.

DESIGN

Fifty-three patients (pts) underwent echocardiographic evaluation of the MR mechanism according to Carpentier's classification; quantification of MR and LV function.

RESULTS

Forty-one, 5% of pts had Type I (annulus dilation), 20, 5% had Type II (commissural prolapse) and 38% had Type IIIb MR (predominant posterior leaflet restriction). Preoperative LV function was slightly better preserved in pts with Type II and IIIb MR. Despite similar MV repair efficiency intraoperatively, after 1 year Type I MR progressed vs the remaining types. LV function, including dimensions, ejection fraction and pulmonary artery pressure had a tendency to worsen in pts with Type I and markedly improved in Type II and IIIb MR.

CONCLUSIONS

Ischemic MR of Type I is associated with more marked LV dysfunction preoperatively, its further deterioration and MR progression after MV repair. Type II and IIIb MR correlates with better preserved LV function preoperatively and its incremental improvement late after surgery.

Papillary muscle rupture following acute myocardial infarction

OBJECTIVES

Papillary muscle rupture following acute myocardial infarction (AMI), which rarely occurs, leads to catastrophic outcomes. We reviewed 6 patients who were diagnosed as having papillary muscle rupture.

SUBJECTS AND METHODS

Between February 1986 and September 2002, 6 consecutive patients underwent mitral valve replacement (MVR) for acute mitral regurgitation due to postinfarction papillary muscle rupture (4 men and 2 women, mean age 67 years). Preoperatively, all were in New York Heart Association (NYHA) class IV. All patients had intraaortic balloon pumping, and one needed additional percutaneous cardiopulmonary support. Operations were performed within 1 to 19 days (mean 6.8) after the onset of AMI, and within 24 hours after papillary muscle rupture. Complete ruptures were found in 5 of 6 patients. Four patients had posterior papillary rupture and 2 patients anterior. All patients underwent MVR to preserve the posterior mitral leaflet. Concomitant coronary artery bypass grafting was performed in 5 of 6 patients (mean 1.6 grafts per person) and pulmonary venous isolation for atrial fibrillation in one patient.

RESULTS

The cardiopulmonary bypass time ranged from 178 to 325 minutes (mean 236), and the aortic cross clamp time from 123 to 196 minutes (mean 155). Two patients died of low cardiac output syndrome. Of 4 operative survivors, 3 patients were in NYHA class I and one in class II. The mean follow-up term was 21 months. One patient with the pulmonary venous isolation has been in sinus rhythm. All survivors have been doing well without any valve related complications.

CONCLUSION

Six patients underwent MVR for the papillary muscle rupture following AMI and the perioperative mortality rate was 33%. All survivors have been well with no cardiac events. We propose that in papillary muscle rupture following AMI emergent surgery should be undertaken as soon as possible, and that concomitant surgery should be performed as thoroughly as possible.

Importance of ischemic and viable myocardium for patients with chronic ischemic mitral regurgitation and left ventricular dysfunction

The objective of this investigation is to determine the importance of ischemic viable myocardium for clinical outcomes in patients with severe chronic ischemic mitral regurgitation and severe left ventricular dysfunction undergoing surgical correction of mitral regurgitation. The study included 54 patients with left ventricular ejection fraction of 27 +/- 9%. Positron emission tomography was performed preoperatively for the identification of ischemic viable myocardium. The patients with a large amount of ischemic viable myocardium (> or =5 segments) had significantly lower 6-month mortality rates than those with less viable myocardium (0 to 4 segments) after the surgery.

Mitral regurgitation following acute myocardial infarction

Mitral valve regurgitation (MR) is a frequent Doppler echocardiographic finding in patients after acute myocardial infarction (AMI) and an independent predictor of long-term cardiovascular mortality. Reported risk factors include advanced age, prior myocardial infarction, infarct extension, and recurrent ischemia. During the early phase of AMI, transient ischemic MR is common and rarely causes hemodynamic compromise. However, when several chordae tendineae or a papillary muscle ruptures, acute left atrial and ventricular volume overload ensues, leading to abrupt hemodynamic deterioration with cardiogenic shock. Auscultation may be unrevealing due to decreased turbulence. Hence, the importance of a high index of suspicion for acute MR in any patient with acute pulmonary edema in the setting of AMI, especially if left ventricular systolic function is well preserved. Later, ventricular remodeling may lead to MR through annular dilatation or papillary muscle migration with malcoaptation of the leaflets. The widespread availability, ease of use and non-invasive nature of Doppler echocardiography have made it the standard diagnostic tool for detecting MR. Mechanical reperfusion of the infarct-related artery seems to be superior to fibrinolysis in decreasing its incidence acutely and in the long run. Nevertheless, when acute severe MR occurs, unless rapidly diagnosed and treated, this dreaded complication is associated with high morbidity and mortality. Prompt surgical intervention after hemodynamic stabilization is essential to ensure a good short-term and long-term prognosis. This review discusses the incidence, long-term prognosis, associated risk factors, complex pathophysiology, time of occurrence, clinical manifestations, diagnosis, and management of patients with MR after AMI.

Patch enlargement of the posterior mitral leaflet in ischemic regurgitation

We discuss our early experience in 2 patients with a patch enlargement technique for treating chronic ischemic mitral regurgitation due to restricted motion of the posterior mitral leaflet. This technique corrects the restricted motion and offers better coaptation without compromising the mitral orifice.

Is repair preferable to replacement for ischemic mitral regurgitation?

OBJECTIVE

This study was undertaken to compare mitral valve repair and replacement as treatments for ischemic mitral regurgitation.

METHODS

From 1985 through 1997, a total of 482 patients with ischemic mitral regurgitation underwent either valve repair (n = 397) or valve replacement (n = 85). Patients more likely (P < or =.01) to undergo repair had functional mitral regurgitation or coronary revascularization with an internal thoracic artery graft; those more likely to receive valve replacement were in higher New York Heart Association functional classes or underwent emergency operations. These factors were used for multivariable propensity matching. Risk factors for early and late death were identified by multivariable, multiphase hazard function analysis.

RESULTS

Within the propensity-matched better-risk group, survivals after valve replacement were 81%, 56%, and 36% at 30 days, 1 year, and 5 years, but survivals after repair were 94%, 82%, and 58% at these intervals (P =.08). In contrast, within the poor-risk group, survivals after repair and replacement were similar (P =.4). Risk factors (P < or =.01) included older age, higher functional class, greater wall motion abnormality, and renal dysfunction. Approximately 70% of patients were predicted to benefit from repair; the benefit lessened or was negated if an internal thoracic artery graft was not used, if a lateral wall motion abnormality was present, or if the mitral regurgitation jet pattern was complex. Freedom from repair failure at 5 years was 91%.

CONCLUSION

Late survival is poor after surgery for ischemic mitral regurgitation. Most patients with ischemic mitral regurgitation benefit from mitral valve repair. In the most complex, high-risk settings, survivals after repair and replacement are similar.

Chordal cutting: a new therapeutic approach for ischemic mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Because such MR is related to increased leaflet tethering by displaced attachments to the papillary muscles (PMs), it is incompletely treated by annular reduction. We therefore addressed the hypothesis that such MR can be reduced by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. This was tested in 8 mitral valves: a porcine in vitro pilot with PM displacement and 7 sheep with acute inferobasal infarcts studied in vivo with three-dimensional (3D) echo to quantify MR in relation to 3D valve geometry.

METHODS AND RESULTS

In all 8 valves, PM displacement restricted leaflet closure, with anterior leaflet angulation at the basal chord insertion, and mild-to-moderate MR. Cutting the 2 central basal chordae reversed this without prolapse. In vivo, MR increased from 0.8+/-0.2 to 7.1+/-0.5 mL/beat after infarction and then decreased to 0.9+/-0.1 mL/beat with chordal cutting (P<0.0001); this paralleled changes in the 3D leaflet area required to cover the orifice as dictated by chordal tethering (r(2)=0.76).

CONCLUSIONS

Cutting a minimum number of basal chordae can improve coaptation and reduce ischemic MR. Such an approach also suggests the potential for future minimally invasive implementation.

Paradoxic decrease in ischemic mitral regurgitation with papillary muscle dysfunction: insights from three-dimensional and contrast echocardiography with strain rate measurement

BACKGROUND

Ischemic mitral regurgitation (MR) was first ascribed to papillary muscle (PM) contractile dysfunction. Current theories include apical leaflet tethering caused by left ventricular (LV) distortion, but PM dysfunction is still postulated and commonly diagnosed. PM contraction, however, parallels apical tethering, suggesting the hypothesis that PM contractile dysfunction can actually diminish MR due to ischemic distortion of the inferior base alone.

METHODS AND RESULTS

We therefore occluded the proximal circumflex circulation in 7 sheep while maintaining PM perfusion, confirmed by contrast echocardiography. By 3D echocardiography, we measured the tethering distance between the ischemic medial PM tip and anterior annulus and LV ejection volume to give MR (by subtracting flowmeter LV outflow). In 6 sheep without initial MR, inferior ischemia alone produced PM tip retraction with restricted leaflet closure and mild-to-moderate MR (regurgitant fraction, 25.2+/-2.8%). Adding PM ischemia consistently decreased MR and tethering distance (5.2+/-0.3 to 1.4+/-0.3 mL; +3.8+/-0.5 mm to -2.2+/-0.7 mm axially relative to baseline; P<0.001) as PM strain rate decreased from +0.78+/-0.07 per second (contraction) to -0.42+/-0.06 per second (elongation, P<0.001) and leaflet tenting decreased. In one sheep, prolapse and MR resolved with inferior ischemia and recurred with PM ischemia.

CONCLUSIONS

PM contractile dysfunction can paradoxically decrease MR from inferobasal ischemia by reducing leaflet tethering to improve coaptation. This emphasizes the role of geometric factors in ischemic MR mechanism and potential therapy.

Three-dimensional geometric comparison of partial and complete flexible mitral annuloplasty rings

BACKGROUND

It has previously been shown in sheep that mitral annular physiologic dynamics during the cardiac cycle are abolished by complete ring annuloplasty, but recent clinical studies suggest that flexible partial ring annuloplasty preserves normal mitral annular dynamics.

METHODS

Eight radiopaque markers were sutured equidistantly around the mitral anulus in 3 groups of sheep: no-ring control animals (n = 16); animals with a flexible Tailor partial ring annuloplasty (n = 6; St Jude Medical, Inc, St Paul, Minn); and animals with a flexible Duran ring annuloplasty (n = 7; Medtronic, Inc, Minneapolis, Minn). After 7 to 10 days' recovery, 3-dimensional marker coordinates were measured by biplane cinefluoroscopy. Mitral annular area and folding (defined as displacement of the mitral anulus from a least-squares plane) and mitral annular septal-lateral and commissure-commissure dimensions were calculated from the 3-dimensional marker coordinates throughout the cardiac cycle every 17 ms.

RESULTS

In the no-ring control group mitral annular area varied from 8.0 +/- 0.2 to 7.2 +/- 0.2 cm(2) (10% +/- 2%), and the septal-lateral and commissure-commissure dimensions varied from 27.7 +/- 0.4 to 25.9 +/- 0.4 mm (7% +/- 1%) and from 38.2 +/- 0.8 to 36.4 +/- 0.8 mm (5% +/- 1%), respectively (mean +/- standard error of the mean, P <.001 for all comparisons). In the Duran ring annuloplasty and Tailor partial ring annuloplasty groups, the anulus was fixed in size throughout the cardiac cycle (area = 4.8 +/- 0.1 and 5.3 +/- 0.3 cm(2), septal-lateral = 21.8 +/- 0.7 and 22.0 +/- 0.8 mm, and commissure-commissure = 27.7 +/- 0.7 and 31.2 +/- 1.7 mm). Mitral annular folding did not differ significantly between the control and Tailor partial ring annuloplasty groups but was dampened in the Duran ring annuloplasty group.

CONCLUSIONS

Partial Tailor flexible ring annuloplasty fixed mitral annular area and dimensions throughout the cardiac cycle in sheep; however, it preserved physiologic mitral annular folding dynamics, which might be important in terms of long-term valve function and prevention of left ventricular outflow tract obstruction.

Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation

OBJECTIVES

This study aimed to separate proposed mechanisms for segmental ischemic mitral regurgitation (MR), including left ventricular (LV) dysfunction versus geometric distortion by LV dilation, using models of acute and chronic segmental ischemic LV dysfunction evaluated by three-dimensional (3D) echocardiography.

BACKGROUND

Dysfunction and dilation-both mechanisms with practical therapeutic implications-are difficult to separate in patients.

METHODS

In seven dogs with acute left circumflex (LCX) coronary ligation, LV expansion was initially restricted and then permitted to occur. In seven sheep with LCX branch ligation, LV expansion was also initially limited but became prominent with remodeling over eight weeks. Three-dimensional echo reconstruction quantified mitral apparatus geometry and MR volume.

RESULTS

In the acute model, despite LV dysfunction with ejection fraction = 23 +/- 8%, MR was initially trace with limited LV dilation, but it became moderate with subsequent prominent dilation. In the chronic model, MR was also initially trace, but it became moderate over eight weeks as the LV dilated and changed shape. In both models, the only independent predictor of MR volume was increased tethering distance from the papillary muscles (PMs) to the anterior annulus, especially medial and posterior shift of the ischemic medial PM, measured by 3D reconstruction (r2 = 0.75 and 0.86, respectively). Mitral regurgitation volume did not correlate with LV ejection fraction or dP/dt.

CONCLUSIONS

Segmental ischemic LV contractile dysfunction without dilation, even in the PM territory, fails to produce important MR. The development of MR relates strongly to changes in the 3D geometry of the mitral apparatus, with implications for approaches to restore a more favorable configuration.

The effects of ring annuloplasty on mitral leaflet geometry during acute left ventricular ischemia

BACKGROUND

The perturbed mitral leaflet geometry that leads to acute ischemic mitral regurgitation during acute left ventricular ischemia has not been quantified, nor is it known whether annuloplasty rings affect these detrimental changes in leaflet geometry.

METHODS

Radiopaque markers were implanted on both mitral leaflets and around the anulus in 3 groups of sheep: one group without rings served as the control group (n = 7); the others underwent Duran (n = 6; Medtronic Heart Valve Division, Minneapolis, Minn) or Carpentier-Edwards Physio (n = 5; Baxter Cardiovascular Division, Santa Ana, Calif) ring annuloplasty. After recovery, 3-dimensional marker coordinates were obtained by means of biplane videofluoroscopy before and during acute posterolateral left ventricular ischemia. Leaflet geometry was defined by measuring distances between annular and leaflet markers and perpendicular distances to the leaflet markers from a best-fit annular plane.

RESULTS

In all control animals, left ventricular ischemia was associated with acute ischemic mitral regurgitation and apical displacement (away from the annular plane) of the posterior leaflet edge and base markers by 0.6 +/- 0.4 mm (P =.01) and 0.7 +/- 0.2 mm (P <.001), respectively. The distance between the posterior leaflet markers and the mid-posterior anulus did not change significantly during ischemia. The anterior leaflet edge marker extended 1.0 +/- 0. 5 mm (P =.01) away from the mid-anterior anulus during ischemia, but compared with its nonischemic position, the anterior leaflet was not displaced apically away from the annular plane. In all animals in the Duran and Physio groups, leaflet geometry was unchanged during ischemia, and acute ischemic mitral regurgitation was not detected.

CONCLUSION

Acute ischemic mitral regurgitation was associated with restricted motion of the posterior leaflet and extension of the anterior leaflet. Annuloplasty rings prevented these geometric perturbations of the mitral leaflets during acute left ventricular ischemia and preserved valvular competence.

Papillary muscle repair surgery in ischemic mitral valve patients

BACKGROUND

Ischemic mitral regurgitation (MR), when ischemia/infarction has resulted in fibrotic degeneration and elongation of papillary muscles, carries a high risk for the patient and a technical challenge for the surgeon. We have developed a papillary-shortening plasty for this specific pathology.

METHODS

Papillary muscle repair was performed in 88 patients (7.2%) where degenerated and fibrotic elongated papillary muscles were found, which resulted in a prolapse of one or more parts of the mitral valve leaflets (MR III-IV). All patients had a papillary muscle-shortening plasty using a pericardium pledged-reinforced polytetrafluoroethylene suture and a ring annuloplasty. Because the cause of regurgitation in this specific group of patients was ischemic, concomitant coronary bypass grafting was required in all patients, with 2.2 grafts/patient.

RESULTS

There were five hospital deaths (5.7%). Postoperative mitral valve function was satisfactory in all patients: no residual mitral regurgitation (MR 0) was found in 80 patients (90.9%), mild regurgitation (MR I) in 5 patients (5.7%), and moderate regurgitation (MR I-II) was observed in 3 patients (3.4%). Within a short mean follow-up period of 18.6 months (3 to 40 months), there was one late death (1.2%). The actuarial freedom from reoperation and thromboembolic complications was 100%, but there were two anticoagulation-induced gastric bleeding complications (2.3%). All patients were in New York Heart Association functional class I or II at the time of follow-up.

CONCLUSIONS

Our data show that careful assessment of papillary muscle pathology is mandatory, and that a papillary muscle-shortening plasty is a simple but valuable surgical tool to repair the mitral valve in this specific group of high-risk patients with ischemic mitral regurgitation.

Design of a new surgical approach for ventricular remodeling to relieve ischemic mitral regurgitation: insights from 3-dimensional echocardiography

BACKGROUND

Mechanistic insights from 3D echocardiography (echo) can guide therapy. In particular, ischemic mitral regurgitation (MR) is difficult to repair, often persisting despite annular reduction. We hypothesized that (1) in a chronic infarct model of progressive MR, regurgitation parallels 3D changes in the geometry of mitral leaflet attachments, causing increased leaflet tethering and restricting closure; therefore, (2) MR can be reduced by restoring tethering geometry toward normal, using a new ventricular remodeling approach based on 3D echo findings.

METHODS AND RESULTS

We studied 10 sheep by 3D echo just after circumflex marginal ligation and 8 weeks later. MR, at first absent, became moderate as the left ventricle (LV) dilated and the papillary muscles shifted posteriorly and mediolaterally, increasing the leaflet tethering distance from papillary muscle tips to the anterior mitral annulus (P<0.0001). To counteract these shifts, the LV was remodeled by plication of the infarct region to reduce myocardial bulging, without muscle excision or cardiopulmonary bypass. Immediately and up to 2 months after plication, MR was reduced to trace-to-mild as tethering distance was decreased (P<0.0001). LV ejection fraction, global LV end-systolic volume, and mitral annular area were relatively unchanged. By multiple regression, the only independent predictor of MR was tethering distance (r(2)=0.81).

CONCLUSIONS

Ischemic MR in this model relates strongly to changes in 3D mitral leaflet attachment geometry. These insights from quantitative 3D echo allowed us to design an effective LV remodeling approach to reduce MR by relieving tethering.

[The practical clinical guidelines of the Sociedad Española de Cardiología on coronary surgery]

Surgery in coronary disease, including myocardial revascularization and the surgery of mechanical complications of acute myocardial infarction, has shown to improve the symptoms, quality of life and/or prognosis in certain groups of patients. The expected benefit in each patient depend on many well-known factors among which the appropriateness of the indication for surgery is fundamental. The objective of these guidelines is to review current indications for cardiac surgery in patients with coronary heart disease through an evaluation of the degree of evidence of effectiveness in the light of current knowledge (systematic review of bibliography) and expert opinion gathered from various reports. Indications and the degree of recommendation for conventional coronary artery bypass grafting have been established for each of the most frequent anatomo-clinical situations defined by clinical symptoms (stable angina, unstable angina and acute myocardial infarction) as well as by left ventricular function and extend of coronary disease. Furthermore, the subgroups with the greatest surgical risk and stratification models are described to aid the decision making process. Also we analyse the rational basis and indication for the new surgical techniques such as minimally invasive coronary surgery and total arterial revascularization. Finally, the indication and timing of surgery in patients with mechanical complications of acute myocardial infarction are considered.

Distortions of the mitral valve in acute ischemic mitral regurgitation

BACKGROUND

In the absence of papillary muscle rupture, the precise deformations that cause acute postinfarction mitral valve regurgitation are not understood and impair reparative efforts.

METHODS

In 6 Dorsett hybrid sheep, sonomicrometry transducers were placed around the mitral annulus (n = 6) and at the tips and bases of both papillary muscles (n = 4). Later, specific circumflex coronary arteries were occluded to infarct approximately 32% of the posterior left ventricle and produce acute 2 to 3+ mitral regurgitation. Before and after infarction, distance measurements between sonomicrometry transducers produced three-dimensional coordinates of each transducer every 5 ms.

RESULTS

After infarction, the annulus dilated asymmetrically orthogonal to the line of leaflet coaptation, but the annular area increased only 9.2% +/- 6.3% (p = 0.02). At end-systole, posterior papillary muscle length increased 2.3 +/- 0.9 mm (p = 0.005); the posterior papillary muscle tip moved closer to the annular plane and centroid, and the anterior papillary muscle tip moved away.

CONCLUSIONS

Small deformations in mitral valvular spatial geometry after large posterior infarctions are sufficient to produce moderate to severe mitral regurgitation. The most important changes are asymmetric annular dilatation, prolapse of leaflet tissue tethered by the posterior papillary muscle, and restriction of leaflet tissue attached to the anterior papillary muscle.

Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry

BACKGROUND

Recent advances in three-dimensional (3D) echocardiography allow us to address uniquely 3D scientific questions, such as the mechanism of functional mitral regurgitation (MR) in patients with left ventricular (LV) dysfunction and its relation to the 3D geometry of mitral leaflet attachments. Competing hypotheses include global LV dysfunction with inadequate leaflet closing force versus geometric distortion of the mitral apparatus by LV dilatation, which increases leaflet tethering and restricts closure. Because geometric changes generally accompany dysfunction, these possibilities have been difficult to separate.

METHODS AND RESULTS

We created a model of global LV dysfunction by esmolol and phenylephrine infusion in six dogs. initially with LV expansion limited by increasing pericardial restraint and then with the pericardium opened. The mid-systolic 3D relations of the papillary muscle (PM) tips and mitral valve were reconstructed. Despite severe LV dysfunction (ejection fraction, 18+/-6%), only trace MR developed when pericardial restraint limited LV dilatation; with the pericardium opened, moderate MR accompanied LV dilatation (end-systolic volume, 44+/-5 mL versus 12+/-5 mL control, P<.001). Mitral regurgitant volume and orifice area did not correlate with LV ejection fraction and dP/dt (global function) but did correlate with changes in the tethering distance from the PMs to the anterior annulus derived from the 3D reconstructions, especially PM shifts in the posterior and mediolateral directions, as well as with annular area (P<.0005). By multiple regression, only changes in the PM-to-annulus distance independently predicted MR volume and orifice area (R2=.82 to .85, P=2x10(-7) to 6x10(-8)).

CONCLUSIONS

LV dysfunction without dilatation fails to produce important MR. Functional MR relates strongly to changes in the 3D geometry of the mitral valve attachments at the PM and annular levels, with practical implications for approaches that would restore a more favorable configuration.

Integrated mechanism for functional mitral regurgitation: leaflet restriction versus coapting force: in vitro studies

BACKGROUND

Functional mitral regurgitation in patients with ischemic or dilated ventricles has been related to competing factors: altered tension on the leaflets due to displacement of their papillary muscle and annular attachments, which restricts leaflet closure, versus global ventricular dysfunction with reduced transmitral pressure to close the leaflets. In vivo, however, geometric changes accompany dysfunction, making it difficult to study these factors independently. Functional mitral regurgitation also paradoxically decreases in midsystole, despite peak transmitral driving pressure, suggesting a change in the force balance acting to create a regurgitant orifice, with rising transmitral pressure counteracting forces that restrict leaflet closure. In vivo, this mechanism cannot be tested independently of annular contraction that could also reduce midsystolic regurgitation.

METHODS AND RESULTS

An in vitro model was developed that allows independent variation of papillary muscle position, annular size, and transmitral pressure, with direct regurgitant flow rate measurement, to test the hypothesis that functional mitral regurgitation reflects an altered balance of forces acting on the leaflets. Hemodynamic and echocardiographic measurements of excised porcine valves were made under physiological pressures and flows. Apical and posterolateral papillary muscle displacement caused decreased leaflet mobility and apical leaflet tethering or tenting with regurgitation, as seen clinically. It reproduced the clinically observed midsystolic decrease in regurgitant flow and orifice area as transmitral pressure increased. Tethering delayed valve closure, increased the early systolic regurgitant volume before complete coaptation, and decreased the duration of coaptation. Annular dilatation increased regurgitation for any papillary muscle position, creating clinically important regurgitation; conversely, increased transmitral pressure decreased regurgitant orifice area for any geometric configuration.

CONCLUSIONS

The clinically observed tented-leaflet configuration and dynamic regurgitant orifice area variation can be reproduced in vitro by altering the three-dimensional relationship of the annular and papillary muscle attachments of the valve so as to increase leaflet tension. Increased transmitral pressure acting to close the leaflets decreases the regurgitant orifice area. These results are consistent with a mechanism in which an altered balance of tethering versus coapting forces acting on the leaflets creates the regurgitant orifice.

Reoperation for failure of mitral valve repair

BACKGROUND AND OBJECTIVE

Mitral valve repair is the procedure of choice to correct mitral regurgitation of all types. Up to 10% of patients who undergo mitral valvuloplasty require late reoperation for recurrent mitral valve dysfunction. To determine the causes of failed mitral valve repair, we examined the surgical pathology of patients who underwent reoperation for failed mitral valve repair.

PATIENTS AND RESULTS

From 1986 to 1994, 81 patients had 86 reoperations for recurrent mitral regurgitation after mitral valve repair. Mean age was 59.2 +/- 1.4 years; 55 were men. Primary valve disease was degenerative in 48 patients (59%), rheumatic in 16 (20%), ischemic in 13 (16%), endocarditic in 3 (4%), and congenital in 1 (1%). Mean time interval between initial mitral valve repair and reoperation was 15.6 +/- 2.5 months. Causes of repair failure were procedure-related (50 cases, 58%), valve-related (33 cases, 38%), or unknown (3 cases, 3%). Procedure-related valve failure was caused by suture dehiscence (21 cases), rupture of previously shortened chordae (19 cases), or incomplete initial correction (10 cases). Valve-related repair failure was caused by progressive primary valve disease (27 cases), endocarditis (5 cases), or extensive leaflet retraction (1 case). Repair failure was procedure-related in 70% of patients with degenerative valvular disease versus only 13% of patients with rheumatic valvular disease (p = 0.0001). At reoperation, mitral valve replacement was performed in 64 patients (79%) and repeat mitral valve repair in 17 (21%).

CONCLUSION

We conclude that (1) most mitral valve repair failures are procedure-related in degenerative disease and valve-related in rheumatic disease; (2) rupture of previously shortened chordae is a common cause of late failure in patients with degenerative mitral valve disease; and (3) repeat mitral valve repair results in successful treatment for a minority of patients.