Left ventricular outflow tract obstruction after mitral valve replacement

A method of posterior mitral annulus remodeling is presented. The posterior annulus is divided into three segments, each segment encircled by a suture that is passed in a tourniquet. Coaptation of the leaflets can be achieved by tightening the tourniquets while the ventricle is being filled. This technique is simple and quick, avoids the use of foreign material, and requires less expertise and judgment than traditional annuloplasties.     

Reversible left intraventricular obstruction after treatment of pheochromocytoma and hyperthyroidism

The authors report an original case of the association of three pathologies: pheochromocytoma, hyperthyroidism and cardiomyopathy with left ventricular outflow tract obstruction. This type of cardiac disease has occasionally been described in cases of pheochromocytoma and are usually induced by the endocrine disturbance because they regress with treatment of the pheochromocytoma. The associated hyperthyroidism observed in this case is very rare and may have increased the left ventricular pressure gradient. Medical treatment before surgery of the pheochromocytoma was unusual in that a triple therapy was used including betablockers, classically contra-indicated in pheochromocytoma alone. In this case, it provided excellent control of the blood pressure and decreased the left ventricular obstruction during the perioperative period.     

Successful surgical repair of left atrial dissection after mitral valve replacement

A rare case of left atrial dissection after mitral valve replacement is reported. Low output syndrome developed in the immediate postoperative period. Cardiac catheterization showed marked elevation of the pulmonary wedge pressure, and left ventriculography revealed massive paraprosthetic leakage with left atrial dissection. At the reoperation, the dissecting cavity was successfully closed from inside the left atrium under cardiopulmonary bypass. We consider this complication another variation of an atrioventricular discontinuity after mitral valve replacement.     

Massive pulmonary hemorrhage complicating mitral prosthetic valve obstruction

A case is reported of prosthetic mitral valve obstruction in a patient who had had three hospital admissions with massive hemoptysis. A diagnosis was finally made after two-dimensional echocardiography with Doppler and cardiac catheterization were performed. The patient was successfully treated with re-replacement of the valve. Any new pulmonary or cardiac symptom in a patient with a prosthetic valve requires prompt evaluation and treatment.     

Video-assisted minimally invasive mitral valve surgery

OBJECTIVE: This study was done to determine the potential benefits of minimally invasive mitral surgery performed with intraoperative video assistance. METHODS: From May 1996 until March 1997, a minithoracotomy and video assistance were used in 31 consecutive patients undergoing mitral repair (n = 20) and replacement (n = 11). Their ages ranged from 18 to 77 years (59 +/- 2.6 years; mean +/- standard error of the mean). Ejection fractions were 35% to 62% (55% +/- 1.5%). Operations were done with either antegrade/retrograde (n = 10) or antegrade (n = 19) cold blood cardioplegia and a new transthoracic crossclamp or with ventricular fibrillation (n = 2). Peripheral arterial cannulation (n = 28) and pump-assisted right atrial drainage (n = 26) were used most often. RESULTS: No hospital deaths occurred, but the 30-day mortality was 3.2%. Complications included deep venous thrombosis and a phrenic nerve palsy in one patient each. No patient had a stroke or required reoperation for bleeding. Postoperative echocardiography showed excellent valve function in all but one patient. Cardiopulmonary bypass and arrest times averaged 183 +/- 7.2 and 136 +/- 5.5 minutes, respectively. Compared with 100 patients having conventional mitral valve operations, these patients had significantly shorter hospitalization times (8.6 +/- 0.5 vs 5.1 +/- 0.9 days, p = 0.05). Moreover, 81% of the later cohort were discharged between day 3 and 5 (3.6 +/- 0.2 days). Hospital charges (decreases 27%, p = 0.05) and costs (decreases 34%, p < 0.05) were less than in conventional operations. Patient follow-up suggested minimal perioperative pain and rapid recovery. CONCLUSIONS: Early results suggest that video-assisted minimally invasive mitral operations can be done safely. These methods may benefit patients through less morbidity, earlier discharge, and lower cost.     

Doppler-derived left ventricular rate of pressure rise and inotropic requirements during mitral valve surgery

OBJECTIVE: Inherited resistance to activated protein C (APC resistance), which is caused by a single point mutation in the factor V gene, is a frequent risk factor for venous thromboembolism. The aim of this study was to determine the prevalence of APC resistance and other coagulation disorders in fertile women with venous thromboembolism and also the risk factors these women had been exposed to in connection with thromboembolic events. DESIGN: A retrospective, case-control study of 36 month duration. SETTING: The study was carried out at Blekinge Hospital, Karlskrona, Sweden. SUBJECTS: The study population comprised 27 fertile women age 16-47 years with thromboembolic complications, referred to the department of Internal Medicine at Blekinge Hospital in Karlskrona during a 36-month period. RESULTS: APC resistance was found in 10 out of 27 women. APC resistance was associated with treatment with oral contraceptives in five out of six women and with pregnancy in one of seven women. All women with resistance to APC developed venous thrombosis in association with a predisposing situation (risk situation) such as surgery, trauma, immobilization, pregnancy, inflammatory state or the use of oral contraceptives. Amongst women not resistant to APC, all but one developed thrombosis in connection with a risk situation. CONCLUSION: APC resistance was found to be highly prevalent amongst fertile women with a history of thromboembolic complication occurring during their use of oral contraceptives.     

A hitherto undescribed cause of prosthetic mitral valve obstruction

A case is described in which severe prosthetic mitral valve obstruction was produced by entanglement of sutures across the central axis of the prosthesis on its ventricular side. The entangled sutures prevented the tilting disc occluder from falling into the left ventricular cavity during ventricular diastole.     

Pulmonary vasoconstriction induced by mitral valve obstruction in sheep

We hypothesized that left atrial hypertension results in pulmonary vasoconstriction, which is obscured by the expected passive decrease in pulmonary vascular resistance. The objectives of this study were to demonstrate and quantify the vasoconstrictive changes that occur in the pulmonary circulation during experimental left atrial hypertension, to determine the site of vasoconstriction, and to explore its mechanism. Sheep were instrumented for measurement of pulmonary arterial (Ppa), left atrial (Pla), and systemic arterial pressures (Psa) with a Foley balloon catheter to variably obstruct the mitral valve. Distal pulmonary arterial wedge pressure (Ppaw) was determined by using a 5-Fr Swan-Ganz catheter that was advanced until it wedged with the balloon deflated. Cardiac output (CO) was estimated by thermodilution; pulmonary vascular resistances (PVR) were calculated as mean (Ppa - Pla)/CO = total PVR, (Ppa - Ppaw)/CO = upstream PVR, and (Ppaw - Pla)/CO = downstream PVR. We studied 15 awake sheep at baseline and during increases in Pla of 10 and 20 cmH2O, with and without inhalation of approximately 36 parts per million of nitric oxide. Left atrial hypertension resulted in elevation of Ppa. CO decreased only slightly at both levels of Pla elevation. Nitric oxide inhalation caused a significant decrease in PVR, which was greater as Pla increased. This vasodilator effect was most striking in downstream vessels. Experiments with phentolamine, atropine, and ibuprofen failed to reveal the mechanism of the reactive pulmonary vasoconstriction.     

Optimizing mitral valve exposure with conventional left atriotomy

The standard surgical approach to the mitral valve is accomplished through a longitudinal incision in the left atrium, posterior and parallel to the interatrial groove. Many other surgical approaches have evolved. This report describes a technique of optimizing mitral valve exposure via the standard approach. These modifications are simple, do not lengthen the procedure, and usually obviate the need for more complex maneuvers.     

Less invasive techniques for mitral valve surgery

This paper reviews the published cost-of-illness studies on obesity. The medical literature has demonstrated that obesity is an independent risk factor for a number of medical conditions, including diabetes mellitus, hypertension, coronary heart disease, elevated cholesterol levels, depression, musculoskeletal disorders, gallbladder disease, and several cancers. Since these conditions can be costly to treat, obesity clearly has a substantial economic impact. Epidemiologic estimates of the aggregate economic costs associated with specific obesity-related diseases in the United States indicate that the annual burden to society totals in the billions of dollars, representing 5.5% to 7.8% of total health-care expenditures. Although estimates of the costs attributable to obesity differ across studies, the one common finding is that these costs are substantial from a health-policy perspective. The objective of this paper is to identify and review the obesity cost-of-illness literature, address study limitations, and identify key areas for future economic research. This review indicates that the economic burden of obesity has been estimated using a prevalence-based cost-of-illness framework. Areas for future research include estimating the economic burden of obesity using an incidence-based cost-of-illness framework and modeling the association between health-care expenditure and level of obesity using individual-level data, such as medical and pharmacy claims data.     

Comparative evaluation of left ventricular performance after mitral valve repair or valve replacement with or without chordal preservation

Germinating barley produces two alpha-amylase isozymes, AMY1 and AMY2, having 80% amino acid (aa) sequence identity and differing with respect to a number of functional properties. Recombinant AMY1 (re-AMY1) and AMY2 (re-AMY2) are produced in yeast, but whereas all re-AMY1 is secreted, re-AMY2 accumulates within the cell and only traces are secreted. Expression of AMY1::AMY2 hybrid cDNAs may provide a means of understanding the difference in secretion efficiency between the two isozymes. Here, the efficient homologous recombination system of the yeast, Saccharomyces cerevisiae, was used to generate hybrids of barley AMY with the N-terminal portion derived from AMY1, including the signal peptide (SP), and the C-terminal portion from AMY2. Hybrid cDNAs were thus generated that encode either the SP alone, or the SP followed by the N-terminal 21, 26, 53, 67 or 90 aa from AMY1 and the complementary C-terminal sequences from AMY2. Larger amounts of re-AMY are secreted by hybrids containing, in addition to the SP, 53 or more aa of AMY1. In contrast, only traces of re-AMY are secreted for hybrids having 26 or fewer aa of AMY1. In this case, re-AMY hybrid accumulates intracellularly. Transformants secreting hybrid enzymes also accumulated some re-AMY within the cell. The AMY1 SP, therefore, does not ensure re-AMY2 secretion and a certain portion of the N-terminal sequence of AMY1 is required for secretion of a re-AMY1::AMY2 hybrid.     

Predictors of left atrial thrombus and spontaneous echo contrast in rheumatic valve disease before and after mitral valve replacement

In this study we aimed to analyze, with reference to mitral regurgitation (MR), the incidence and predictors of left atrial (LA) thrombus and spontaneous echo contrast in patients with rheumatic valve disease before and after mitral valve replacement. The incidence of LA thrombus is known to be less in patients with MR. The impact of mitral valve replacement on this beneficial effect has not been studied in detail. The study included 169 consecutive patients (59 men and 110 women, average age 40 +/- 13 years) with rheumatic mitral valve disease who underwent transesophageal echocardiographic examination 1 to 3 days before and within 7 days (mean 4.0 +/- 1.3) after mitral valve replacement using mechanical prostheses in a single institution. The preoperative incidence of echocardiographic LA spontaneous echo contrast (SEC) was 1.1%, 30%, and 54%, and the incidence of thrombus was 1.1%, 13%, and 17% in the groups with MR, combined mitral stenosis + MR, and isolated mitral stenosis, respectively. In the MR group, SEC and thrombus incidence increased significantly after surgery. The independent predictors for postoperative thrombus development were atrial fibrillation, postoperative SEC, and preoperative thrombus. Thrombus recurred after surgery in 64% of 14 patients who had surgical thrombectomy. The presence of postoperative MR was associated with decreased risk of postoperative SEC and thrombus development. The interaction between MR and SEC and thrombus both before and after surgery provides further support for the protective effect of MR against LA thrombus formation.     

Thirty years experience with heart valve surgery: isolated mitral valve replacement

BACKGROUND: Thirty years have elapsed since the commencement of open-heart surgery in South Australia. A retrospective study was performed to evaluate mortality and complication rates and to identify factors associated with poor outcomes in all patients who underwent prosthetic mitral valve replacement during this period. METHODS: Questionnaires and personal contact have been used to generate a combined database of pre-operative and post-operative information and long-term follow-up on 938 patients who underwent isolated prosthetic mitral valve replacement at the Cardio-Thoracic Surgical Unit of the Royal Adelaide Hospital between 1963 and 1993. RESULTS: Complete survival follow-up data were obtained for 92% (865) of the patients. The Starr-Edwards valve was used in 95% (891) of the patients, a Bjork-Shiley prosthesis in 2.5% (23) of the patients, and only 24 (2.5%) other valves were inserted. The hospital mortality rate for the 30-year period was 4.7%. The mean age of the patients who underwent surgery was greater in each of the three successive decades. A long-term survival advantage was observed for patients with mitral stenosis, however, survival was significantly shorter for patients with higher New York Heart Association (NYHA) functional classifications and for patients in pre-operative atrial fibrillation. Pre-operative dyspnoea was significantly improved following mitral valve replacement. The rates of postoperative haemorrhagic and embolic complications were low by comparison with other published series. CONCLUSION: Mitral valve recipients do not regain a normalized life expectancy, but risk factors that determine long-term survival can be identified pre-operatively to aid appropriate patient selection.     

Interference of mitral valve stenosis with left ventricular diastole and left atrial appendage flow

Atrial fibrillation (AF) has been reported as an independent risk factor of systemic thromboembolism. Almost half of the left atrial thrombi are located in the left atrial appendage (LAA). LAA function, reflected by LAA flow, thus has an influence on the potential of distal embolic complications. To identify factors other than atrial contraction that influence LAA flow during AF, transthoracic and transesophageal echocardiographic studies were performed on 130 patients. Seventy patients with nonrheumatic AF were divided into two groups with higher peak LAA outflow velocity (group 1) and lower peak LAA outflow velocity (group 2) at the ventricular systolic phase. Sixty patients with rheumatic AF were classified as group 3. Group 1 had a higher peak LAA outflow velocity than group 2 at both the ventricular systolic and diastolic phases. Group 2 had a higher peak LAA outflow at the ventricular diastolic phase than group 3 (18.9 +/- 8.0 vs. 11.8 +/- 7.5 cm/s, p < 0.001), whereas there was no significant difference in the peak LAA outflow at the ventricular systolic phase between the two groups (9.6 +/- 4.0 vs. 10.8 +/- 6.8 cm/s, p = NS). Group 3 was subdivided according to mitral valve area. Patients with severe mitral stenosis (mitral valve area < 1 cm2) had a significantly lower diastolic augmentation of LAA outflow velocity (difference of LAA outflow velocity between ventricle systole and diastole) than patients with mild to moderate stenosis (0.5 +/- 3.2 vs. 2.6 +/- 4.9 cm/s, p < 0.05). In conclusion, patients with rheumatic AF, especially those with severe mitral stenosis, have a lower diastolic augmentation of LAA outflow velocity. The lower diastolic augmentation of the LAA outflow velocity at the ventricular diastolic phase might result from interference with the suction effect of the left ventricular diastole by the stenotic mitral valve.     

Transesophageal echocardiography in the detection and surgical management of a papillary fibroelastoma of the mitral valve causing partial mitral valve obstruction

Duchenne muscular dystrophy (DMD) is an X-chromosome-linked myopathy caused by a defect in the DMD gene. Intragenic deletions appear to be the most common gene defect leading to DMD, and the deletion frequency has been estimated to be 66%. Results of this study using a group of 24 DMD patients of Sri Lankan origin employing the technique of multiplex DNA amplification using the polymerase chain reaction indicated a deletion frequency of 62.5%. Eighty per cent of these deletions were localized in a region of the DMD gene regarded as a 'hot spot' for DMD deletions. Our results are in agreement with the results of other studies carried out on Caucasian populations.     

Noonan syndrome: structural abnormalities of the mitral valve causing subaortic obstruction

Among 41 consecutive children with classic Noonan syndrome, 27 patients (66%) presented cardiac anomalies. Eight patients (19.5%) had a congenital anomaly of the mitral valve consisting of 5 with partial atrioventricular canal defect and 3 with anomalous insertion of the mitral valve on the ventricular septum. Five patients (12%) presented with a significant left ventricular outflow tract obstruction caused by the anterior leaflet of the mitral valve: two cases with atrioventricular canal and three cases with isolated anomalous insertion of the mitral valve. Echocardiography is the best tool for the diagnosis. Cardiac defects of patients with Noonan syndrome may be explained on the basis of anomalies of the extracellular matrix involving cardiac valves including the mitral valve. CONCLUSION: In children with Noonan syndrome and left ventricular hypertrophy a careful echocardiographic assessment of the mitral valve should reveal those in whom the left ventricular outflow tract obstruction is anatomical in nature.