Surgery of the mitral valve and the management of mitral stenosis in pregnant women.
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Disease Management↗
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Abnormalities in elastic fibers and other connective-tissue components of floppy mitral valve.
Histologic, immunohistochemical, and ultrastructural studies were performed on 12 floppy mitral valves, 4 mitral valves showing focal myxomatous changes without prolapse, and 3 normal mitral valves. All floppy mitral valves were thickened by deposits of proteoglycans and also showed diverse structural abnormalities in collagen and elastic fibers. From these observations we conclude that (1) the structure of all major components of connective tissue in floppy mitral valves is abnormal; (2) alterations in collagen and accumulations of proteoglycans are nonspecific changes that may be caused by the abnormal mechanical forces to which floppy mitral valves are subjected because of their excessively large surface area; (3) the presence of excessive amounts of proteoglycans may interfere with the normal assembly of collagen and elastic fibers; (4) abnormalities of elastic fibers resemble those in other conditions characterized by structural dilatation or tissue expansion; and (5) alterations in elastin could result from defective formation, increased degradation, or both.
Actin Cytoskeleton↗
Is the mitral valve passive flap theory overstated? An active valve is hypothesized.
The concept that the mitral valve of the heart is a passive flap that opens and closes like a barn door has been emphasized for decades by medical and biology professors to their students. But experimental findings, which are outlined in this report, support the theory of an active valve. We hypothesize that the two leaflets of the mitral valve are actively contractile; that physical forces generated in the valve itself may stabilize and add precision to the sum of forces that regulate valve movement. This precision could be of critical significance both in the moments preceding, and during, valve opening and closing. Evidence supporting our active valve hypothesis includes the profuse innervation of motor and sensory nerves that are present in the mitral valves of all animals studied. In addition, multiple contractile cell types have been found in the mitral valve, including cardiac muscle cells, smooth muscle cells, and cardiac valvular interstitial cells. In vitro work in our laboratories using the rat mitral valve shows that not only are the valves capable of contraction and relaxation, but that the contractions and relaxations are nerve-mediated. We theorize that the rich innervation and contractile cells in the mitral valve work together to modulate fine-tuning of valve movements and tone, thereby ensuring the integrity of the valve seal. Other investigators have reported that the mitral valve demonstrates contractile activity and that denervation localized to the mitral valve affects valve competence. The evidence for an active mitral valve presented by these and other experimental studies warrant a reexamination of the validity of the passive valve concept. An accurate and full understanding of the precise movements of the valve leaflets and the mechanisms that regulate these movements is likely to provide the information needed to understand and develop treatments for many different cardiac valve problems, including mitral valve diseases such as prolapse and myxomatous degeneration. In view of the available experimental evidence, the concept that the mitral valve functions only as a passive structure is challenged by numerous anomalies. A reinterpretation of the concept of valve function that incorporates active as well as passive roles for the valve leaflets and other components of the valve apparatus would have significant implications both for the directions taken in research involving the cardiac valves and for the approaches to treatment.
Animals↗
The long-term results of mitral valve reconstruction for the "floppy" valve.
The myxomatous degenerated, prolapsed, or floppy mitral valve is the most common etiology of mitral regurgitation in North American populations. We performed mitral valve reconstruction for this diagnosis in 252 patients from 1984 to 1993. There were 165 males and 87 females ranging in age from 23 to 84 years (mean 64 years); 93 (37%) were > or = 70 years. One hundred eighty-six were New York Heart Association Functional Class III or IV and 29% (72) underwent concomitant coronary bypass operation. Operations included posterior leaflet resection, anterior leaflet resection treatment of chordal pathology by shortening or Gore-Tex replacement, and ring annuloplasty. There were five operative deaths for an operative mortality of 2%. The operative risk in patients under 70 years was 1 of 159 (0.6%) and 4 of 93 (4%) in patients older than 70 years. Ninety percent of patients are asymptomatic in a follow-up period extending 10 years, while structural valve degeneration requiring reoperation at 5 years was 85%. From 1990 to 1993 there has been a less than 5% absolute incidence of structural valve degeneration. Mitral valve reconstruction for complicated floppy mitral valve is feasible and offers excellent early and medium-term results.
Adult↗
Impact of mitral valve annuloplasty on mortality risk in patients with mitral regurgitation and left ventricular systolic dysfunction.
OBJECTIVES: This study was designed to assess effects of mitral valve annuloplasty (MVA) on mortality in patients with mitral regurgitation (MR) and left ventricular (LV) systolic dysfunction. BACKGROUND: Mitral valve annuloplasty improves hemodynamics and symptoms in these patients, but effects on long-term mortality are not well established. METHODS: We retrospectively analyzed consecutive patients with significant MR and LV systolic dysfunction on echocardiography between 1995 and 2002. Cox regression analysis, including MVA as a time-dependent covariate and propensity scoring to adjust for differing probabilities of undergoing MVA, was used to identify predictors of death, LV assist device implantation, or United Network for Organ Sharing-1 heart transplantation. RESULTS: Of 682 patients identified, 419 were deemed surgical candidates; 126 underwent MVA. Propensity score derivation identified age, ejection fraction, and LV dimension to be associated with undergoing MVA. End points were reached in 120 (41%) non-MVA and 62 (49%) MVA patients. Increased risk of end point was associated with coronary artery disease (hazard ratio [HR] 1.80, 95% confidence interval [CI] 1.30 to 2.49), blood urea nitrogen (HR 1.01, 95% CI 1.005 to 1.02), cancer (HR 2.77, 95% CI 1.45 to 5.30), and digoxin (HR 1.66, 95% CI 1.15 to 2.39). Reduced risk was associated with angiotensin-converting enzyme inhibitors (HR 0.65, 95% CI 0.44 to 0.95), beta-blockers (HR 0.59, 95% CI 0.42 to 0.83), mean arterial pressure (HR 0.98, 95% CI 0.97 to 0.99), and serum sodium (HR 0.93, 95% CI 0.90 to 0.96). Mitral valve annuloplasty did not predict clinical outcome. CONCLUSIONS: In this analysis, there is no clearly demonstrable mortality benefit conferred by MVA for significant MR with severe LV dysfunction. A prospective randomized control trial is warranted for further study of mortality with MVA in this population.
Aged↗
Long-term results of mitral valve reconstruction with Carpentier techniques in 148 patients with mitral insufficiency.
There have been few relatively complete follow-up studies of long-term mitral valve function after Carpentier-type surgical reconstruction. Between January 1980 and May 1986, 148 patients underwent Carpentier reconstruction for mitral valve disease (43% degenerative and 30% rheumatic). Operative mortality was 5.4% overall (1.2% for isolated mitral reconstruction), and follow-up (mean, 26 months) was completed for all survivors. Five-year survival from late cardiac death was 90.0%, as was 5-year freedom from postreconstruction mitral valve replacement. Postreconstruction mitral replacement was needed in eight patients, in only five for failure of repair. Follow-up echocardiographic studies on 83.2% (104 of 125) of eligible patients showed 92.3% were free of significant (3+ or 4+) mitral regurgitation. Freedom from mitral valve replacement or recurrent severe (4+) insufficiency was 84.4% at 5 years overall, but was lower for the rheumatic type of mitral disease than for the degenerative type (71.6% vs. 88.3%). At 5 years, 95.2% of patients were free from thromboembolism without the necessity for long-term warfarin (Coumadin) therapy. At follow-up, 95.3% of survivors had improved to New York Heart Association Class I or II. The functional durability of mitral reconstruction and consistently high level of freedom from late endocarditis and thromboembolic and anticoagulant complications support the value of the Carpentier method of mitral reconstruction for mitral insufficiency, especially insufficiency due to degenerative disease.
Adolescent↗
Is the mitral valve area flow-dependent in mitral stenosis? A dobutamine stress echocardiographic study.
OBJECTIVES: The purpose of this study was to compare the effect of changes in flow rate on the mitral valve area (MVA) derived from two-dimensional echocardiographic planimetry and Doppler pressure half-time (PHT) methods in patients with mitral stenosis (MS). BACKGROUND: Dobutamine stress echocardiography has been proposed as a means of assessing the severity of MS. However, data regarding the effect of an increase in flow rate on MVA are limited. If MVA is indeed flow-dependent, this has important implications for the assessment of the severity of MS, particularly in the setting of reduced cardiac output (CO). METHODS: Dobutamine echocardiography was performed in 57 patients with isolated MS who were in sinus rhythm. The MVA was determined by planimetry and Doppler PHT methods. RESULTS: Cardiac output increased by > or =50% in 27 patients (group I) and by <50% in 30 patients (group II). In group I, the MVA by planimetry increased by only 10.6 +/- 2% and the MVA by PHT increased by 21.9 +/- 4.8%. These changes were similar to those observed in group II (10.7 +/- 3% and 14.8 +/- 4%, respectively; p = NS), despite a much smaller increase in CO. A clinically important change (from the severe to mild category) occurred in only one patient when using the PHT method and in none by planimetry. CONCLUSIONS: Changes in flow rate result in small but clinically insignificant changes in echocardiographic MVA measurement. These methods provide an accurate assessment of MS severity in a majority of patients, independent of changes in flow rate.
Adolescent↗
[Anesthetic management for mitral valve replacement in a patient with mitral stenosis and dilated cardiomyopathy].
A 42-year-old man with dilated cardiomyopathy and rheumatic mitral stenosis underwent mitral valve replacement. Prior intravascular fluid administration and infusion of dopamine and dobutamine stabilized hemodynamics during the induction of anesthesia. High-dose fentanyl at pre-cardiopulmonary bypass period and circulatory assist with milrinone and intraaortic balloon pumping after the bypass enabled us to obtain stable hemodynamics. Preoperative dobutamine stress test provided us the effective information for circulatory management in this patient.
Adult↗
[Re-do surgery with minimally invasive cardiac surgery (MICS): mitral valve replacement 6 years after open mitral commissurotomy].
A 60-year-old man, who had undergone open mitral commissurotomy 6 years ago, underwent re-do surgery (mitral valve replacement) with minimally invasive cardiac surgery (MICS), using lower partial sternotomy to the height of the right side second intercostal space. Cannulation of the heart was carried out placing a cannula directly into the superior vena cava and a second cannula in the inferior vena cava via the right atrium. Arterial return was through the ascending aorta. Cardioplegia was administered directly into the ascending aorta with intermittent perfusion. Valve replacement was performed by opening directly right side left atrium.
Cardiac Surgical Procedures↗
[Basedow's disease and mitral valve prolapse].
The prevalence of mitral valve prolapse was investigated in 60 patients with Graves' disease (42 with ophthalmopathy) and in 20 patients with toxic nodular goitre. 2410 patients from the echocardiography laboratory served as controls. Standard M-mode, Doppler and two-dimensional echocardiography were performed. Mitral valve prolapse was defined as a systolic buckling greater than or equal to 3 mm. In patients with thyroid disease HLA antigens were determined. Patients with Graves' disease showed a significantly higher incidence of mitral valve prolapse (36/60, 60%) compared to the group with toxic nodular goitre (2/20, 10%) and to controls (238/2410, 9,9%) (P less than 0.0001). 16 of 36 patients had a prolapse of the anterior, in 3 of 36 the posterior leaflet was involved and 17 of 36 had both. Mean systolic buckling was 4.3 +/- 1.5 mm. 28 of 42 patients with ophthalmopathy (67%) showed a mitral valve prolapse. 20 of 60 patients (33.3%) with Graves' disease but none in the goitre group showed a thickened myxomatous valve (P less than 0.001). Thyroid function did not influence the incidence and intensity of the prolapse. The HLA phenotypes B8 were seen in 22 of 36 and DR3 in 24 of 36 patients with mitral valve prolapse. Since thyroid function was comparable in both groups an involvement of the mitral valve in an autoimmune process affecting several organs can be considered probable.
Adult↗
Hemoptysis, recurrent cerebrovascular accident, and emergency mitral valve replacement.
Hemoptysis in mitral stenosis may occur frequently, but massive pulmonary hemorrhage is uncommon. We describe a patient with mitral stenosis who had severe hemoptysis and required anticoagulation for recurrent embolic cerebrovascular accidents. The patient underwent successful mitral valve replacement with a Hancock bioprosthesis. There was no evidence of pulmonary bleeding following operation. This case illustrated that mitral valve operation may be performed in acutely ill patients for the relief of hemoptysis.
Adult↗
[Complications of idiopathic mitral valve prolapse. Prevention and treatment].
Mitral valve prolapse is the most common form of heart disease, as it occurs in 4 to 6 per cent of the population. It has a benign course in the majority of cases, but 5 types of severe complication can occur in 15 per cent of cases. Mitral incompetence occurs in 14.8 per cent of cases. It may develop gradually or suddenly, following rupture of the chordae, which requires rapid surgical repair. Mitral valve prolapse is complicated by infectious endocarditis in 2.9 per cent of cases, hence the need for antibiotic prophylaxis prior to dental treatment or surgery in patients with a pan-systolic or end-systolic murmur. The only arrhythmias which should be considered as complications and treated as such are frequent ventricular extrasystoles of more than 30 per hour, usually associated with bigeminy, runs or polymorphism, ventricular tachycardia and ventricular fibrillation. Treatment consists, primarily, of beta-blockers. Sudden death is of course the major complication, occurring in 1.4 to 2.4 per cent of cases. The patients at risk of this complication are middle-aged women (40 years) with a past history of syncope or faintness due, in most cases, to episodes of ventricular tachycardia or ventricular fibrillation. Apart from arrhythmia, coronary artery spasm has also been found to be a cause of sudden death in these patients. Transient or definitive ocular and cerebral ischaemic episodes can also complicate mitral valve prolapse. Mitral valve prolapse is found in 20 to 30 per cent of patients with neurological accidents before the age of 45. Preventative treatment consists of anti-platelet aggregation agents and anticoagulants in recurrent cases.
Adrenergic beta-Antagonists↗
[Mitral valve remodeling using valvuloplasty, chordoplasty and ring annuloplasty].
Degenerative mitral valve disease is a major cause of mitral regurgitation and mitral valve repair has acquired greater importance as a surgical treatment of mitral regurgitation. Since 1991 we have used mitral valve repair to remodel the mitral valve leaflet, chordae tendineae and annulus. The final aim of our mitral valve remodeling technique is to correct the coaptation line of both leaflets. Forty-eight patients who underwent mitral valve repair were analyzed to evaluate the effect of the mitral valve reconstructive technique. We compared the left ventricular function and mitral valvular function by echocardiography and also the left ventricular pressure volume area, which reflects the oxygen consumption of the myocardium, before and after operation. The actuarial survival from all deaths, including one hospital death and one noncardiac death, was 95.8% at 60 months. Three patients have required reoperation because of recurrent regurgitation. Freedom from reoperation at 5 years was 93.8%. Left ventricular end-diastolic (122.3 +/- 45.8-->66.4 +/- 33.8 ml/ m2) and end-systolic volume indexes (39.6 +/- 19.5-->30.1 +/- 18.9 ml/m2) significantly decreased after mitral valve repair, and left ventricular volume overload was markedly reduced. Left ventricular ejection fraction and fractional shortening, which were apparently good before operation, were within the normal range after operation. Left ventricular inflow velocity and mitral pressure gradient were unchanged before and after repair. Mitral valve orifice area was 3.20 +/- 1.08 cm2 and did not show signs of mitral stenosis after repair. The reduction of left ventricular pressure volume area after repair was 53.6 +/- 12.4%, showing marked reduction of the oxygen consumption of the myocardium after successful mitral repair. Left ventricular and mitral valvular function is well preserved after mitral valve remodeling. Mitral valvular function after mitral repair exceeds that of the mitral valve replacement. Mitral valve remodeling procedures are very useful for patients with mitral regurgitation due to mitral valve prolapse.
Adolescent↗
Cyclic elevation of intrathoracic pressure can close the mitral valve during cardiac arrest in dogs.
Mitral valve closure during cardiopulmonary resuscitation may result from direct cardiac compression. An alternative hypothesis is that with a rise in intrathoracic pressure, mitral valve closure can occur but may be influenced by whether the lungs are inflated or deflated. To test this hypothesis, we placed a large-bore cannula into the thoraces of 11 dogs. Intrathoracic pressure was changed by inflating and deflating the thorax through the cannula while the airway was open, as well as by inflating and deflating the lungs with the thoracic cannula clamped. Mitral valve motion was observed with two-dimensional echocardiography from the right chest wall or esophagus in eight of the dogs. With a rise in intrathoracic pressure from thoracic inflation, all eight dogs showed closure of the mitral valve, while with thoracic deflation, all showed mitral valve opening. With lung inflation and deflation alone, however, the mitral valve remained open throughout the cycle. In seven dogs, with thoracic inflation, the peak gradient from the left ventricle to the left atrium was (mean +/- SEM) 18 +/- 4 mm Hg and the average gradient was 7 +/- 3 mm Hg, while with lung inflation alone, the average gradient was -1 +/- 1 mm Hg (p less than 0.01 vs. thoracic inflation). Thus, mitral valve closure, with concomitant retrograde pressure gradients, can be produced by intrathoracic pressure changes with accompanying lung deflation. With lung inflation alone, however, the mitral valve remains open, and there are no significant transmitral pressure gradients. We conclude that intrathoracic pressure changes can cause the mitral valve to close or to remain open, depending on how intrathoracic pressure is generated.
Animals↗
Patient-related risk factors as predictors of results following isolated mitral valve replacement.
Results following isolated mitral valve replacement in 897 consecutive patients over a twelve-year period were analyzed with regard to the influence of various preoperative patient-related risk factors. Actuarial data analysis allowed definition of major preoperative, etiological, clinical, and hemodynamic correlates to both perioperative and long-term postoperative patient survival. Patient age below 60 years, preoperative New York Heart Association Functional Class of III or less, cardiac index greater than 2.0, and left ventricular end-diastolic pressure of less than 12 mm Hg were all highly significant correlates of improved perioperative as well as long-term patient survival. Patients whose predominant functional lesion was mitral insufficiency had only a 53% five-year survival (187 of 352 patients) following mitral valve replacement as opposed to 70% (521 of 745 patients) for those who had mixed or stenotic mitral lesions. Primary ischemic mitral dysfunction was associated with only 31% five-year survival (17 of 54 patients) after mitral valve replacement in contrast to 69% (480 of 695 patients) for patients with rheumatic mitral lesions. The presence of occlusive coronary artery disease coexisting with, but not the primary cause of, mitral dysfunction was associated with decreased perioperative and late postoperative survival. Results support both earlier operative intervention and wider use of associated procedures, ie, coronary bypass grafting, with mitral valve replacement. Recognition of major preoperative patient-related risk factors should enhance survival following this procedure.
Adult↗
Double-crowned valved stents for off-pump mitral valve replacement.
OBJECTIVE: An animal model has been designed to assess the feasibility of off-pump mitral valve replacement using valved stents. METHODS: Glutaraldehyde-preserved homograft was sutured inside a prosthetic tube (Dacron). Then, two self-expandable nitinol Z-stents were sutured on the external surface of the prosthesis in such a way to create two self-expanding crowns for fixation. In adult pigs and under general anesthesia, the left atrium was exposed through a left thoracotomy and atrio-ventricular roadmapping was performed with intravascular ultrasound (IVUS) and fluoroscopy. The double-crowned valved stents were loaded into a delivery sheath. The sheath was then introduced into the left atrium and the valved stents was deployed in mitral position in such a way that the part in between the two stents was at the level of the mitral annulus. Intracardiac Unltrasound (ICUS) was used to assess the valve function. Hemodynamic parameters were gathered as well. Animal survived for no more than 3h after the valve deployment and gross anatomy examination of the left heart was carried out. RESULTS: The mean height of the valved stents was 29.4+/-0.2 mm, with an internal diameter of 20.4+/-1.0mm, and an external diameter of 25.5+/-0.8 mm. The procedure was successfully carried out in eight animals. In vivo evaluation showed a native mitral annulus diameter of 24.9+/-0.6 mm, and a mean mitral valve area of 421.4+/-17.5 mm2. ICUS showed a mild mitral regurgitation in three out of eight animals. Mean pressure gradient across the valved stents was 2.6+/-3.1 mmHg. Mean pressure gradient across the left ventricular outflow tract (LVOT) was 6.6+/-5.2 mmHg. The mean survival time was 97.5+/-56.3 min (survival time range was 40-180 min). One animal died due to the occlusion of the LVOT because of valved stents displacement. Postmortem evaluation confirmed correct positioning of the valved stent in the mitral position in seven out of eight animals. No atrial or ventricular lesions due to the valved stents were found. CONCLUSIONS: Off-pump implantation of a self-expandable valved stent in the mitral position is technically feasible. Further studies will assess if this procedure is also feasible in humans.
Animals↗
Small valve area index: its influence on early mortality after mitral valve replacement.
OBJECTIVE: To test the hypothesis that mitral valve prosthesis-patient mismatch increases postoperative mortality. METHODS AND RESULTS: The effect of mitral valve prosthesis-patient mismatch on survival in a cohort of consecutive patients after mitral valve replacement with a mechanical prosthesis was measured, focusing on the lower tail of the normal distribution curve of the prosthetic valve area index. For the calculation of the geometric valve area index (cm(2)/m(2) body surface area), we used specifications for the geometric valve area supplied by the manufacturer. The cut-off value of the 10th percentile of the valve area index was 1.919 cm(2)/m(2). The study population consisted of 428 adult patients who underwent mitral valve replacement by a Medtronic Hall (n=270, 63%) or a St. Jude Medical prosthesis (n=158, 37%). The size of the valves implanted ranged from 25 mm to 31 mm. The valve area index showed a normal distribution curve ranging from 1.43 to 2.98 cm(2)/m(2) with a mean of 2.2 cm(2)/m(2). Group 1 (n=33) had a valve area index <1.9 cm(2)/m(2) and group 2 (n=395), > or =1.9 cm(2)/m(2). The 30-day mortality was higher in group 1 than in group 2 (18.2 vs. 4.1%, P=0.005). Multivariate logistic regression analysis of the determinants of the 30-day mortality rendered a small valve area index (<1.9 cm(2)/m(2)) as an independent risk indicator: relative risk 4.3 (95% CI 1.6-9.5; P=0. 0043). The difference in overall survival between the two groups was entirely due to the high 30-day mortality in the patients with small valve area indices, congestive heart failure being the main cause of death. CONCLUSIONS: By concentrating on the extreme lower tail of the normal distribution of the valve area index, a strong and independent relation was found between relatively small valves (valve area index <1.9 cm(2)/m(2)) and 30-day mortality. We found no influence of valve size on late mortality beyond the first 30 days.
Adult↗
Valvular heart disease, Part 2. Mitral valve disease in older adults.
Mitral valve disease is a common cause of morbidity and mortality in patients over age 65. The etiology, physical findings, and natural history of rheumatic mitral stenosis, rheumatic mitral regurgitation, chronic non-rheumatic mitral regurgitation, and acute mitral regurgitation may differ in older and younger patients. In addition, symptoms of mitral valve disease may be masked or exacerbated by coexistent coronary artery disease, pulmonary disease, hypertension, and other systemic disorders that commonly occur in older adults. The clinical evaluation, along with various non-invasive cardiac procedures, is important for identifying mitral valve disease as the cause of abnormal signs and symptoms in older patients. Recognition of mitral valve abnormalities has important implications, because mitral valve repair or replacement is usually associated with favorable short- and long-term results, even in patients over age 65.
Aged↗