Geometric differences of the mitral apparatus between ischemic and dilated cardiomyopathy with significant mitral regurgitation: real-time three-dimensional echocardiography study.

BACKGROUND: This study was conducted to elucidate the geometric differences of the mitral apparatus in patients with significant mitral regurgitation caused by ischemic cardiomyopathy (ICM-MR) and by idiopathic dilated cardiomyopathy (DCM-MR) by use of real-time 3D echocardiography (RT3DE). METHODS AND RESULTS: Twenty-six patients with ICM-MR caused by posterior infarction, 18 patients with DCM-MR, and 8 control subjects were studied. With the 3D software, commissure-commissure plane and 3 perpendicular anteroposterior (AP) planes were generated for imaging the medial, central, and lateral sides of the mitral valve (MV) during mid systole. In 3 AP planes, the angles between the annular plane and each leaflet (anterior, Aalpha; posterior, Palpha) were measured. In ICM-MR, Aalpha measured in the medial and central planes was significantly larger than that in the lateral plane (39+/-5 degrees, 34+/-6 degrees, and 27+/-5 degrees, respectively; P<0.01), whereas Palpha showed no significant difference in any of the 3 AP planes (61+/-7 degrees, 57+/-7 degrees, and 56+/-7 degrees, P>0.05). In DCM-MR, both Aalpha (38+/-8 degrees, 37+/-9 degrees, and 36+/-7 degrees, P>0.05) and Palpha (59+/-6 degrees, 58+/-5 degrees, and 57+/-6 degrees, P>0.05) revealed no significant differences in the 3 planes. CONCLUSIONS: The pattern of MV deformation from the medial to the lateral side was asymmetrical in ICM-MR, whereas it was symmetrical in DCM-MR. RT3DE is a helpful tool for differentiating the geometry of the mitral apparatus between these 2 different types of functional mitral regurgitation.

Glycosaminoglycan profiles of myxomatous mitral leaflets and chordae parallel the severity of mechanical alterations.

OBJECTIVES: This biochemical study compared the extracellular matrix of normal mitral valves and myxomatous mitral valves with either unileaflet prolapse (ULP) or bileaflet prolapse (BLP). BACKGROUND: Myxomatous mitral valves are weaker and more extensible than normal valves, and myxomatous chordae are more mechanically compromised than leaflets. Despite histological evidence that glycosaminoglycans (GAGs) accumulate in myxomatous valves, previous biochemical analyses have not adequately examined the different GAG classes. METHODS: Leaflets and chordae from myxomatous valves (n = 41 ULP, 31 BLP) and normal valves (n = 27) were dried, dissolved, and assayed for deoxyribonucleic acid, collagen, and total GAGs. Specific GAG classes were analyzed with selective enzyme digestions and fluorophore-assisted carbohydrate electrophoresis. RESULTS: Biochemical changes were more pronounced in chordae than in leaflets. Myxomatous leaflets and chordae had 3% to 9% more water content and 30% to 150% higher GAG concentrations than normal. Collagen concentration was slightly elevated in the myxomatous valves. Chordae from ULP had 62% more GAGs than those from BLP, primarily from elevated levels of hyaluronan and chondroitin-6-sulfate. CONCLUSIONS: The GAG classes elevated in the myxomatous chordae are associated with matrix microstructure and elastic fiber deficiencies and may influence the hydration-related "floppy" nature of these tissues. These abnormalities may be related to the reported mechanical weakness of myxomatous chordae. The biochemical differences between ULP and BLP confirm previous mechanical and echocardiographic distinctions.

Surgical ablation of atrial fibrillation with bipolar radiofrequency as the primary modality.

OBJECTIVES: In studying cardiac surgical patients undergoing atrial fibrillation ablation with bipolar radiofrequency, we sought to (1) quantify the time-related prevalence of atrial fibrillation postoperatively and identify its risk factors and (2) determine time-related ablation failure and its risk factors. METHODS: From November 2001 to January 2004, 513 patients underwent atrial fibrillation ablation (bipolar radiofrequency alone or with cryothermy) and other cardiac operations. Rhythm documented on 3495 postoperative electrocardiograms was used to estimate the prevalence of and risk factors for atrial fibrillation across time. Ablation failure was defined as occurrence of atrial fibrillation any time beyond 6 months after operation. RESULTS: Prevalence of postoperative atrial fibrillation peaked at about 1 month, decreased to 13% at 6 months, and gradually increased thereafter. Risk factors associated with increased prevalence varied by time period and included older age ( P = .004) for early occurrence, lesion set in permanent atrial fibrillation ( P = .02) for late occurrence, and larger left atrial diameter ( P = .02) and permanent atrial fibrillation ( P < .0001) for occurrence across the entire time span. Freedom from ablation failure was 72% at 12 months. Risk factors for ablation failure included lesion set in permanent atrial fibrillation ( P = .001), longer duration of atrial fibrillation ( P = .01), and larger left atrial diameter ( P = .03). CONCLUSIONS: Bipolar radiofrequency enables extension of ablation to most cardiac surgical patients with atrial fibrillation. Recurrence is influenced by the type and duration of atrial fibrillation, choice of lesion set in permanent atrial fibrillation, and left atrial size. Early operation, careful choice of lesion set, and left atrial reduction might enhance results.

Tricuspid valve repair for biopsy-induced regurgitation in a heart transplant recipient.

Tricuspid regurgitation (TR) is a frequent complication after heart transplantation. The etiology of TR is multifactorial, but biopsy-induced flail leaflet is one of the most important mechanisms. A 61-year-old woman underwent heart transplant, but experienced several rejection episodes which required multiple surveillance endomyocardial biopsies. At three months after transplant, she required tricuspid valve repair due to symptomatic severe TR. The anterior leaflet was flail, with rupture of primary and secondary chordae. Valve repair was performed with a triple leaflet edge-to-edge technique. The procedure consisted of suture fixation of the prolapsed anterior leaflet joining to the septal and posterior leaflets, and placement of a 30-mm annuloplasty ring. The patient was uneventfully discharged home on day 7 with trivial TR. At a four-years post-transplant evaluation, she was in NYHA functional class I, with preserved ventricular function and trivial TR. She has been followed closely because of post-transplant coronary artery disease.

In vitro performance of the novel coronary sinus AutoRetroPerfusion Cannula.

Myocardial salvage through coronary sinus intervention has been documented. The AutoRetroPerfusion Cannula is a novel device that is able to perfuse the coronary bed retrogradely through the coronary sinus with arterial blood generated from a peripheral artery with no need for a pump. The cannula consists of a distal end that, once secured in the coronary sinus, opens an umbrella-like membrane to create pressure in the coronary sinus, and at the same time has small channels directed backwards to the right atrium to provide pressure relief. The cannula is introduced from the axillary vein under local anesthesia and the proximal end, which consists of a graft, is anastomosed to the axillary artery to start autoperfusion once the distal end is secured in the coronary sinus and the occluding membrane is open. The AutoRetroPerfusion Cannula was tested in the in vitro mock loop under 50-120 mm Hg of proximal pressure and 50, 100, and 150 ml/min of total flow in the cannula. We were able to achieve the nominal design point of 40-80 mm Hg of distal pressure and 50-150 ml/min of distal flow by adjusting the number, diameter, and length of the small backwards channels.

Biomechanical and echocardiographic characterization of flail mitral leaflet due to myxomatous disease: further evidence for early surgical intervention.

BACKGROUND: Flail mitral leaflet (FML) is a common complication of mitral valve prolapse, often leading to severe mitral regurgitation (MR) and left ventricular dysfunction. In the absence of timely surgical correction, survival is significantly impaired. Early recognition of FML and identification of risk factors is important because early intervention increases the chances of survival. METHODS: We studied 123 patients undergoing mitral valve surgery for severe MR caused by myxomatous disease. Chart review, echocardiography, and tensile testing were performed. RESULTS: Thirty-eight patients had FML, and 85 patients had non-flail mitral leaflet (non-FML). Patients with FML were younger (53.7 +/- 1.8 vs 59.3 +/- 1.4 years, P =.02), had more severe MR (3.89 +/- 0.04 vs 3.76 +/- 0.04, P =.02), were less likely to be in New York Heart Association class III or IV heart failure (5% vs 20%, P =.037), and were less likely to have bileaflet mitral valve prolapse (5% vs 38%, P <.001) than non-FML patients. Valve tissue from patients with FML had less stiff chordae (23.5 +/- 3.6 vs 59.1 +/- 11.7 Mpa, P =.006) that tended to have a lower failure stress (3.8 +/- 0.9 vs 9.6 +/- 2.2 Mpa, P =.07) and had more extensible leaflets (56.4% +/- 7.9% vs 42.9% +/- 2.7% strain, P =.04) compared with that of non-FML patients. CONCLUSIONS: The development of FML may result from intrinsic tissue abnormalities and is associated with a distinct subset of the myxomatous population. Identification of such clinical characteristics in this population and knowledge of an implicit mechanical abnormality of valve tissue may further the argument for early surgical correction.

Clinical, echocardiographic, and biomechanical differences in mitral valve prolapse affecting one or both leaflets.

Mitral valve prolapse (MVP) is the most common cause of severe mitral regurgitation necessitating surgical correction. Unileaflet prolapse (ULP), usually involving the posterior leaflet, is more common than bileaflet prolapse (BLP), which is more difficult to repair. Little is known about clinical, echocardiographic, and biomechanical differences between ULP and BLP. In this study, biomechanical testing was performed on mitral valve leaflets and chordae obtained at operation for severe mitral regurgitation. Preoperative clinical characteristics and echocardiographic measurements were obtained on surgical patients (ULP = 88, BLP = 37). Men outnumbered women by a factor of 4:1 in ULP, and by 3:1 in BLP. Patients with BLP were younger (53.2 +/- 1.7 vs 59.5 +/- 1.1 years) than those with ULP, and this difference was greater in women (48.9 +/- 2.5 vs 62.9 +/- 2.2 years). BLP patients were less likely to be hypertensive, and more likely to undergo valve replacement rather than repair. Echocardiography showed that BLP leaflets were longer and thicker than ULP leaflets. The severity of mitral regurgitation was similar in both groups, although ULP patients had a much higher incidence of flail leaflets (45% vs 5% in BLP). Mechanical strength of chordae was greater in BLP than in ULP, although leaflet strength was similar. The increased chordal strength in BLP may be responsible for less flail. In patients with MVP and severe mitral regurgitation requiring surgery, ULP and BLP are distinct entities with substantial differences in the population affected, in echocardiographic manifestations including prevalence of flail, in chordal mechanics, and in the likelihood of surgical repair.

Vacuum-assisted venous return reduces blood usage.

OBJECTIVE: To determine whether vacuum-assisted venous return has clinical advantages over conventional gravity drainage apart from allowing the use of smaller cannulas and shorter tubing. METHODS: A total of 150 valve operations were performed at our institution between February and July 1999 using vacuum-assisted venous return with small venous cannulas connected to short tubing. These were compared with (1) 83 valve operations performed between April 1997 and January 1998 using the initial version of vacuum-assisted venous return, and (2) 124 valve operations performed between January and April of 1997 using conventional gravity drainage. Priming volume, hematocrit value, red blood cell usage, and total blood product usage were compared multivariably. These comparisons were covariate and propensity adjusted for dissimilarities between the groups and confirmed by propensity-matched pairs analysis. RESULTS: Priming volume was 1.4 +/- 0.4 L for small-cannula vacuum-assisted venous return, 1.7 +/- 0.4 L for initial vacuum-assisted venous return, and 2.0 +/- 0.4 L for gravity drainage (P <.0001). Smaller priming resulted in higher hematocrit values both at the beginning of cardiopulmonary bypass (27% +/- 5% compared with 26% +/- 4% and 25% +/- 4%, respectively, P <.0001) and at the end (30% +/- 4% compared with 28% +/- 4% and 27% +/- 4%, respectively, P <.0001). Red cell transfusions were used in 17% of the patients having small-cannula vacuum-assisted venous return, 27% of the initial patients having vacuum-assisted venous return, and 37% of the patients having gravity drainage (P =.001); total blood product usage was 19%, 27%, and 39%, respectively (P =.002). Although ministernotomy also was associated with reduced blood product usage (P <.004), propensity matching on type of sternotomy confirmed the association of vacuum-assisted venous return with lowered blood product usage. CONCLUSIONS: Vacuum-assisted venous return results in (1) higher hematocrit values during cardiopulmonary bypass and (2) decreased red cell and total blood product usage.

Equivalent midterm outcomes after off-pump and on-pump coronary surgery.

OBJECTIVE: Multiple reports demonstrate that off-pump surgery reduces the early morbidity associated with coronary artery bypass grafting. To determine if there are any differences in later outcomes, we compared midterm results of propensity-matched patients who underwent off- and on-pump coronary artery bypass grafting. METHODS: From January 1997 to July 2000, 481 patients underwent off-pump coronary artery bypass grafting and 3231 underwent on-pump coronary artery bypass grafting. Propensity matching was used to match 406 patients from each group. Previously, the propensity-matched off-pump patients were found to have had significantly fewer bypass grafts. These 812 patients were followed for time-related events, including death, myocardial infarction, percutaneous coronary intervention, coronary reoperation, and the combined end point of all-cause mortality, myocardial infarction, and all coronary reintervention. Follow-up was 95% complete. RESULTS: At 4 years, survival was 87.5% after off-pump and 91.2% after on-pump coronary artery bypass grafting (P =.2); freedom from myocardial infarction was 92.6% and 95.7% (P =.7), respectively; freedom from percutaneous coronary intervention was 94.3% and 95.5% (P =.9), respectively; freedom from coronary reoperation was 98.1% and 99.0% (P =.4), respectively; and freedom from the combined end point of all-cause mortality, myocardial infarction, and coronary reintervention was 75.2% and 82.9% (P =.14), respectively. CONCLUSIONS: Off-pump and on-pump coronary artery bypass grafting results in equivalent midterm outcomes. Fewer bypass grafts in the off-pump patients did not decrease survival or increase ischemic events at 4 years.

Tricuspid valve repair: durability and risk factors for failure.

OBJECTIVES: To compare durability of tricuspid valve annuloplasty techniques, identify risk factors for repair failure, and characterize survival, reoperation, and functional class of surviving patients. METHODS: From 1990 to 1999, 790 patients (mean age 65 +/- 12 years, 51% New York Heart Association functional class III or IV, and mean right ventricular systolic pressure 56 +/- 18 mm Hg) underwent tricuspid valve annuloplasty for functional regurgitation using 4 techniques: Carpentier-Edwards semi-rigid ring, Cosgrove-Edwards flexible band, De Vega procedure, and customized semicircular Peri-Guard annuloplasty. Of these patients, 89% had concomitant mitral valve surgery. A total of 2245 follow-up transthoracic echocardiograms were retrieved. Tricuspid regurgitation was analyzed, and risk factors for worsening regurgitation were identified, by multivariable ordinal longitudinal methods. RESULTS: Tricuspid regurgitation 1 week after annuloplasty was 3+ or 4+ in 14% of patients. Regurgitation severity was stable across time with the Carpentier-Edwards ring (P =.7), increased slowly with the Cosgrove-Edwards band (P =.05), and rose more rapidly with the De Vega (P =.002) and Peri-Guard (P =.0009) procedures. Risk factors for worsening regurgitation included higher preoperative regurgitation grade, poor left ventricular function, permanent pacemaker, and repair type other than ring annuloplasty. Right ventricular systolic pressure, ring size, preoperative New York Heart Association functional class, and concomitant surgery were not risk factors. Tricuspid reoperation was rare (3% at 8 years), and hospital mortality after reoperation was 37%. CONCLUSIONS: Tricuspid valve annuloplasty did not consistently eliminate functional regurgitation, and across time regurgitation increased importantly after Peri-Guard and De Vega annuloplasties. Therefore, these repair techniques should be abandoned, and transtricuspid pacing leads should be replaced with epicardial leads.

Repair versus replacement for degenerative mitral valve disease with coexisting ischemic heart disease.

OBJECTIVE: We sought to compare mitral valve repair and replacement as treatments for degenerative mitral valve disease with coexisting ischemic heart disease. Specifically, we sought to (1) identify differences between patients undergoing repair and replacement, (2) determine whether the choice of mitral valve procedure affected survival after adjusting for those differences, and (3) discover which patients were predicted to benefit from mitral valve repair and which from replacement. METHODS: From 1973 to 1999, 679 patients (mean age, 67 +/- 9.1 years; 73% men) with degenerative mitral valve and ischemic heart diseases underwent combined coronary artery bypass grafting and either mitral valve repair (66%) or replacement (34%). Factors associated with repair and replacement were used for multivariable propensity matching. Risk factors for death were identified by means of multivariable, multiphase hazard-function analysis. RESULTS: Patients more likely to undergo repair had isolated posterior chordal rupture (P <.0001) or more recent date of operation (P <.0001); those more likely to undergo replacement were older (P =.0003) or had bileaflet prolapse (P <.0001). Unadjusted survival at 30 days and 1, 5, and 10 years was 97%, 92%, 79%, and 59% after repair and 94%, 88%, 70%, and 37% after replacement. After adjusting for comorbid factors, the extent and effect of ischemic heart disease, and propensity score, the survival benefit of repair became evident after 2 years (P =.01). Eighty-nine percent of patients were predicted to benefit from repair. CONCLUSIONS: In patients with degenerative mitral valve and ischemic heart diseases, mitral valve repair confers a survival advantage over replacement that becomes evident about 2 years after the operation.

Mitral valve repair with aortic valve replacement is superior to double valve replacement.

OBJECTIVES: Double valve replacement has been advocated for patients with combined aortic and mitral valve disease. This study investigated the alternative that, when feasible, mitral valve repair with aortic valve replacement is superior. PATIENTS AND METHODS: From 1975 to 1998, 813 patients underwent aortic valve replacement with either mitral valve replacement (n = 518) or mitral valve repair (n = 295). Mitral valve disease was rheumatic in 71% and degenerative in 20%. Mitral valve replacement was more common in patients with severe mitral stenosis (P =.0009), atrial fibrillation (P =.0006), and in patients receiving a mechanical aortic prosthesis (P =.0002). These differences were used for propensity-matched multivariable comparisons. Follow-up extended reliably to 16 years, mean 6.9 +/- 5.9 years. RESULTS: Hospital mortality rate was 5.4% for mitral valve repair and 7.0% for replacement (P =.4). Survivals at 5, 10, and 15 years were 79%, 63%, and 46%, respectively, after mitral valve repair versus 72%, 52%, and 34%, respectively, after replacement (P =.01). Late survival was increased by mitral valve repair rather than replacement (P =.03) in all subsets of patients, including those with severe mitral valve stenosis. After repair of nonrheumatic mitral valves, 5-, 10-, and 15-year freedom from valve replacement was 91%, 88%, and 86%, respectively; in contrast, after repair of rheumatic valves, it was 97%, 89%, and 75% at these intervals. CONCLUSIONS: In patients with double valve disease, aortic valve replacement and mitral valve repair (1) are feasible in many, (2) improve late survival rates, and (3) are the preferred strategy when mitral valve repair is possible.

Prosthesis size and long-term survival after aortic valve replacement.

OBJECTIVE: This study was undertaken to quantify the relationship between prosthesis size adjusted for patient size (prosthesis-patient size) and long-term survival after aortic valve replacement. METHODS: Data from nine representative sources on 13,258 aortic valve replacements provided 69,780 patient-years of follow-up (mean 5.3 +/- 4.7 years), with reliable survival estimates to 15 years. Prostheses included 5757 stented porcine xenografts, 3198 stented bovine pericardial xenografts, 3583 mechanical valves, and 720 allografts. Manufacturers' labeled prosthesis size was 19 mm or smaller in 1109 patients. Expressions of prosthesis-patient size assessed were indexed internal prosthesis orifice area (in centimeters squared per square meter of body surface area) and standardized internal prosthesis orifice size (Z, the number of SDs from mean normal native aortic valve size). Multivariable hazard domain analysis with balancing score and risk factor adjustment quantified the association of prosthesis-patient size with survival. RESULTS: Prosthesis-patient size down to at least 1.1 cm(2)/m(2) or -3 Z did not adversely affect intermediate- or long-term survival (P >.2). However, 30-day mortality increased 1% to 2% when indexed orifice area fell below 1.2 cm(2)/m(2) (P =.002) or standardized orifice size fell below -2.5 Z (P =.0003). The increased early risk affected fewer than 1% of patients receiving bioprostheses but about 25% of those receiving mechanical devices. CONCLUSIONS: Aortic prosthesis-patient size down to 1.1 cm(2)/m(2) or -3 Z did not reduce intermediate- or long-term survival after aortic valve replacement. However, patient-prosthesis size under 1.2 cm(2)/m(2) or -2.5 Z was associated with a 1% to 2% increase in 30-day mortality. Prosthesis-patient sizes this small or smaller were rarely implanted in patients receiving bioprostheses.

Recurrent mitral regurgitation after annuloplasty for functional ischemic mitral regurgitation.

OBJECTIVES: We sought to characterize the temporal return of mitral regurgitation after annuloplasty for functional ischemic mitral regurgitation; to identify its predictors, particularly with respect to annuloplasty type; and to determine whether annuloplasty type influences survival. METHODS: From April 1985 through November 2002, 585 patients underwent annuloplasty alone for repair of functional ischemic mitral regurgitation, generally with concomitant coronary revascularization (95%). A flexible band (Cosgrove) was used in 68%, a rigid ring (Carpentier) in 21%, and bovine pericardial annuloplasty (Peri-Guard) in 11%. Six hundred seventy-eight postoperative echocardiograms were available in 422 patients to assess the time course of postoperative mitral regurgitation and its correlates. Most echocardiograms were performed early after the operation (median, 8 days); 17% were performed at 1 year or beyond. RESULTS: During the first 6 months after repair, the proportion of patients with 0 or 1+ mitral regurgitation decreased from 71% to 41%, whereas the proportion with 3+ or 4+ regurgitation increased from 13% to 28% ( P < .0001); the regurgitation grade was stable thereafter. The temporal pattern of development of 3+ or 4+ regurgitation was similar for Cosgrove bands and Carpentier rings (25%) but substantially worse for Peri-Guard annuloplasties (66%). Small annuloplasty size did not influence postoperative regurgitation grade ( P = .2), although Cosgrove bands were used in most patients receiving 26- and 28-mm annuloplasties. Freedom from reoperation was 97% at 5 years. Annuloplasty type was not associated with survival. CONCLUSIONS: Although initial mitral valve replacement would eliminate the risk of postoperative mitral regurgitation, this strategy has been associated with reduced survival. Therefore the development of additional techniques is necessary to achieve more secure repair of functional ischemic mitral regurgitation.

Does off-pump coronary surgery reduce morbidity and mortality?

OBJECTIVE: To compare hospital outcomes of on-pump and off-pump coronary artery bypass surgery. METHODS: From 1997 to 2000, primary coronary artery bypass grafting was performed in 481 patients off pump and in 3231 patients on pump. Hospital outcomes were compared between propensity-matched pairs of 406 on-pump and 406 off-pump patients. The 2 groups were similar in age (P =.9), left ventricular function (P =.7), extent of coronary artery disease (P =.5), carotid artery disease (P =.4), and chronic obstructive pulmonary disease (P =.5). However, off-pump patients had more previous strokes (P =.05) and peripheral vascular disease (P =.02); on-pump patients had a higher preoperative New York Heart Association class (P =.01). RESULTS: In the matched pairs the mean number of bypass grafts was 2.8 +/- 1.0 in off-pump patients and 3.5 +/- 1.1 in on-pump patients (P <.001). Fewer grafts were performed to the circumflex (P <.001) and right coronary (P =.006) artery systems in the off-pump patients. Postoperative mortality, stroke, myocardial infarction, and reoperation for bleeding were similar in the 2 groups. There was more encephalopathy (P =.02), sternal wound infection (P =.04), red blood cell use (P =.002), and renal failure requiring dialysis (P =.03) in the on-pump patients. CONCLUSIONS: Both off- and on-pump procedures produced excellent early clinical results with low mortality. An advantage of an off-pump operation was less postoperative morbidity; however, less complete revascularization introduced uncertainty about late results. A disadvantage of on-pump bypass was higher morbidity that seemed attributable to cardiopulmonary bypass.

Failed mitral valve repair caused by polypropylene suture.

A 65-year-old man with degenerative mitral valve disease had mitral valve repair consisting of posterior leaflet resection and leaflet repair with polypropylene suture and annuloplasty. Six years later, he presented with recurrent mitral regurgitation. The cut tail of a polypropylene suture used at the initial repair had eroded the free edge of the anterior leaflet and its chordae. Chordal transfer was used to re-repair the valve. Soft, braided suture is preferred for leaflet approximation at mitral valve repair; if polypropylene suture is used, suture tails and knots should be positioned such that they do not come into contact with leaflet tissue.