Tricuspid valve replacement after orthotopic heart transplantation

Atrioventricular valvular regurgitation is a known complication after cardiac transplantation. In this communication, we describe a case of progressively severe tricuspid insufficiency that ultimately necessitated tricuspid valve replacement. The patient has done well clinically since valve replacement, and a postoperative cardiac catheterization demonstrated normal right heart hemodynamics. A discussion of proposed causes and a review of the literature are provided.     

Mitral valve replacement under beating heart in 137 cases

To avoid damage of myocardial ischemia, myocardial hypoxia and reperfusion injury, we designed mitral valve replacement in beating heart under extracorporeal circulation with low dose temperature of 31 degrees C to 35 degrees C in 137 cases of rheumatic heart disease, congenital heart disease mitral stenosis and mitral insufficiency, or concurrent aortic insufficiency. The patients were rept in unblocking aorta, unfilling cardiac arrest perfusion, idle pulse and dradycardia of 40-50 times/min, nose temperature of 32 +/- 1 degrees C. Patients with concurrent aortic insufficiency should first undergo replacement of aorta under cold cardiac arrest and then replacement mitral valve under beating heart to reduce the time of cold heart ischemia. Plastic surgery for tricuspid valve was done under beating heart. Good postoperative prognosis was nated: an average arterial pressure of 9.5-10.5 kPa (70 to 80 mmHg), dose of dopamine was obviously reduced. No low cardiac output syndrome, acute renal failure and severe arrythmia were observed in 137 cases, except 4 deaths due to infection and blood coagulation (2.9%). A left cardiac chamber no-level air removal device and aorta perfusioner leading flow device were designed for exsufflation of left pneumatocardia.     

Exercise tests before and after heart valve replacement

A simple progressive exercise test was performed before and after operation on five subjects undergoing mitral valve replacement and on five subjects undergoing aortic valve replacement. The responses of heart rate and ventilation were related to work rate )kilopond metres/min). The patients were also assessed clinically by the New York Heart Association grading and radiologically before each exercise test. The clinical grading was shown to be a poor guide to observed exercise tolerance, as the improvement noted in symptoms was not matched by the objective measurement of working capacity. Only two patients had normal exercise tolerance after surgery, although six of the ten patients claimed that they had no exertional dyspnoea after operation. The changes in simple ventilatory function tests before and after operation were generally small. We suggest that measurements of exercise tolerance before and after operation should be an essential part of heart valve replacement surgery.     

Blood rheology in patients with native heart valve disease and after valve replacement

Patients with heart valve disease have rheologic abnormalities that are more pronounced in double valve disease than in mitral or aortic valve disease; after valve replacement surgery, the degree of rheologic abnormality is more pronounced in patients with mechanical and biological prostheses than in those with homografts and pulmonary autografts. Rheologic abnormalities seen in these patients might be related to the different incidences of thromboembolism in the presence of various valve defects and various types of prostheses.     

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.     

Anticoagulant control in the first three months after mechanical heart valve replacement

To establish the precision of anticoagulant control in the first three months after mechanical heart valve replacement, 53 patients from a consecutive series of 91 were telephoned and asked to read out their anticoagulation record. The levels of international normalised ratio (INR) were analysed by Rosendaal's method. Twenty-nine per cent of patient days were spent with an INR in the recommended range of 3.0-4.5. Warfarin dosage was increased at a median INR of 2.1 (interquartile range 1.7-2.3), unchanged at 2.7 (interquartile range 2.3-3.1) and decreased at 4.3 (interquartile range 3.6-5.1). Anticoagulant control is poor in the first three months after mechanical heart valve replacement. Data on the INR at which warfarin dosage is changed suggest either that recommended guidelines are not being followed or a reluctance to increase the dosage in patients receiving inadequate anticoagulation.     

Mid-term surgical results after valve replacement with the CarboMedics valve prosthesis

Located at the level of the Z-line, the transverse cytoskeletal network of insect-flight muscle interconnects adjacent myofibrils with one another, and interconnects peripheral myofibrils with the cell membrane. This network has been presumed to keep myofibrils in register, or to distribute tension laterally among myofibrils. In this study, we used scanning-electron microscopy to reveal details of the three-dimensional arrangement of this network. The network is seen to interconnect longitudinal elements of the cytoskeletal network which surround each myofibril. The arrangement is not unlike that seen in vertebrate skeletal muscle. Interestingly, the transverse network makes contact with cell components such as dense bodies and mitochondria. Such contacts imply potential roles over and above those noted above. The network may be involved not only in mechanical function, but possibly also in intracellular communication.     

Improvement in mitral regurgitation after aortic valve replacement

This study sought to determine whether there is a quantitative improvement in mitral regurgitation (MR) after aortic valve replacement (AVR) for aortic stenosis (AS) and, if so, the mechanisms for this change. MR frequently accompanies AS. The addition of mitral valve replacement to AVR significantly increases the risk of surgery. Although previous studies have suggested a qualitative improvement in MR severity after AVR, semiquantitative analysis of this improvement has not been documented nor have the underlying mechanisms been examined. We evaluated 28 patients who had undergone 2-dimensional echo and color flow Doppler imaging an average of 1.5 +/- 2.5 months before and 2.5 +/- 4.2 months after AVR. Maximum MR area, MR percentage (MR area/left atrial area), mitral annular area, left atrial area, aortic gradient, and parameters of left ventricular geometry were measured to evaluate MR severity and to assess functional mechanisms for improvement in MR. There was a significant decrease in MR area (5.5 +/- 2.8 cm2 vs 2.5 +/- 1.9 cm2, p < or =0.0001) and MR percentage (25 +/- 11% vs 12 +/- 10% after operation, p < or =0.0001) between preoperative and postoperative studies. There was a significant reduction in aortic gradient, mitral annular area, left atrial area, and left ventricular length postoperatively. In univariate analysis, MR improvement was related to the lower preoperative left ventricular fractional area change (p = 0.027) and to the changes in fractional area change (p = 0.001) and left ventricular systolic area (p = 0.001). Thus, improvement in MR after AVR is related to changes in left ventricular function postoperatively. These data suggest that reduction in MR is due not only to decreased intraventricular pressure, but also to changes in ventricular morphology.     

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.     

Aortic valve replacement after previous coronary artery bypass grafting

BACKGROUND: As the population ages, an increasing number of patients with previous coronary artery bypass grafting (CABG) will require subsequent aortic valve replacement (AVR). This study examined outcome of AVR after previous CABG and reviewed possible indications for valve replacement at the time of initial myocardial revascularization. METHODS: Between March 1975 and December 1994, 145 patients had AVR after previous CABG. Sixty-three patients (43%) had their initial CABG elsewhere. Reoperation for AVR was the second cardiac procedure in 137 patients and the third in 8. Redo CABG with AVR was done in 66 (46%). There were 118 men and 27 women. The mean age at CABG was 64 +/- 7.9 years; for AVR this was 71 +/- 7.6 years. RESULTS: In 2 young patients accelerated calcific aortic stenosis occurred in the setting of renal failure. Significant aortic stenosis did not appear to be addressed at initial CABG in 3 patients. Transaortic valvular gradient, as measured by cardiac catheterization, increased by 10.4 +/- 7.0 mm Hg/y. Twenty-four patients (16.6%) died. The mortality for AVR alone or for AVR + redo-CABG was 15 of 125 patients (12%). For patients having more complicated procedures, the mortality was 9 of 20 (45%). Nine patients (6.2%) suffered a postoperative cerebrovascular accident. Low preoperative ejection fraction measured by echocardiography, sternal reentry problems, complexity of operation, and prolonged cross-clamp and bypass times were significant factors associated with mortality. Age at AVR, interval between operations, the extent of underlying native coronary artery disease, the state of the previously placed bypass conduits, and methods of myocardial preservation were not significant predictors of operative mortality. On multivariate analysis there was only one significant value: prolonged cross-clamp time. CONCLUSIONS: Aortic valve replacement after previous CABG is associated with a mortality that is higher than that seen after repeat CABG or repeat AVR. It seems prudent, therefore, to use liberal criteria for AVR in those patients who require coronary revascularization and who, at the same time, have mild or moderate aortic valve disease.     

Echocardiography after mitral valve replacement and criteria of paraprosthetic regurgitation

19 patients with Bj?rk-Shiley mitral tilting disc valve prostheses were studied by echocardiography before the valve replacement operation and postoperatively every three months up to one year. In 14 patients with normal prosthetic function the left atrial diameter decreased markedly after operation (p less than 0.001), but echocardiographic dimensional indices of left ventricular performance remained unchanged. Paradoxical or markedly hypokinetic motion of the interventricular septum was observed within 3 months of operation in 46% of the patients, but in only 28% in studies performed 9 - 12 months after the replacement. The ampliture of the disc was on average 11 +/- 2 mm. In 5 patients with paraprosthetic regurgitation the left atrial diameter increased with the development of regurgitation and decreased again after successful reoperation. In these patients the left ventricular end diastolic and stroke volumes were great (p less than o.01) than in patients with normal prostheses. The septal motion was in the normal direction in all these 5 patients and the septal amplitudes were greater (p less than 0.01) than in the patients with normal prostheses. The amplitudes of the disc were normal, but abnormal anterior movement of the disc at the beginning of the diastole was observed. These data demonstrate that echocardiography is useful in the diagnosis of paraprosthetic mitral valve regurgitation.     

Native valve staphylococcal endocarditis: etiology, risk factors and outcome in 53 cases

Pump manufacturers recommend setting roller pump occlusion such that the level of a 100 cm column of crystalloid drops 2.5 cm/min (Sarns, 8000 Modular Perfusion System, operator's manual, roller pump software version 2.3L. May 1993; 2.1-2.14). Though this almost occlusive setting ensures accurate pump flow, it has been shown to cause more hemolysis than nonocclusive pumps (Noon GP, Kane LE, Feldman L et al. Reduction of blood trauma in roller pumps for long-term perfusion. World J Surg 1985; 9: 65-71). We conducted a clinical study (n = 19) to compare the standard occlusion method with the dynamic method and to determine the accuracy of flow for the nonocclusive pump. Standard occlusion was set by clamping the pump tubing distal to the arterial line filter and timing the drop in pump outlet pressure as indicated by a pressure transducer connected to the filter. The occlusion setting, expressed in mmHg/s, was recorded for each roller at two specific points along the raceway. The pump was then set nonocclusively with the dynamic method using the Better Header (BH) (Circulatory Technology, Oyster Bay, NY, USA). Readings of the change in pressure in the same two selected points on the raceway were taken. The latter was repeated after discontinuation of bypass. Flow was recorded throughout the procedure from both roller pump output display and a flow meter (Model #109 Transonic, Ithaca, NY, USA). The average drop in pump outlet pressure for the standard method was 1.3 +/- 4.0 (range 0-18 mmHg/s), and for the dynamic method was 38 +/- 28 (range 1.2-89 mmHg/s). Off bypass, the average reading was 44 +/- 38 (range 2.0-103 mmHg/s). Regression analysis indicates that patient flow, when corrected for retrograde flow by the dynamic method, equals 1.003 x revolutions per minute + 40 ml/min (r2 = 0.964). The average error between indicated pump flow, corrected for retrograde flow, was -1% (range from -6.7 to 6.6%). We conclude that the BH allows nonocclusive setting (30 times less than our standard method) without sacrificing pump flow accuracy.     

Results of heart valve replacement: especially on the selection criteria for valve prostheses and on a new anticoagulation regimen

Since March 1981 till the end of 1987, a total of 76 artificial heart valves were implanted in 72 patients. Heart valve prostheses were selected individually according to the patient's needs rather than assigning a single model to every patient. Postoperatively patients were placed on an anticoagulation therapy regimen consisting of reduced-dose warfarin (prothrombin time maintained at 30% of the control) and a small dose (81 mg/day) aspirin. During this period no bioprosthesis was implanted. For aortic valves, Starr-Edwards caged-ball valves were used in 53.1% and St. Jude Medical (SJM) valves in 37.5%. For mitral valves, SJM valves were used in 68%. No mechanical valve failure and no thrombosed valve was encountered. There was one patient-prosthesis missmatch. The incidence of thromboembolism for the entire series was 5/181.2 patient-years. There was 1-2/181.2 patient-years incidence of hemorrhagic complications. These figures were comparable to the ones with conventional warfarin therapy. No intracranial hemorrhage was encountered. Our selection criteria for artificial heart valves and our method of anticoagulation were discussed in detail. We conclude that at present there is no single prosthesis which satisfies all the varying needs of every patient, and the prosthesis which is best suited to that particular patient should be selected. We are generally happy with our current method of postoperative anticoagulation and will continue with this regimen.     

Successful surgical treatment of a pseudoaneurysm after composite graft replacement of the aortic valve and ascending aorta: report of two cases

Composite graft replacement of the ascending aorta and aortic valve has now become a safe surgical procedure; however, early and late complications still frequently occur. Anastomotic dehiscence after a composite graft replacement is one potentially lethal complication. We herein report two cases of a pseudoaneurysm caused by dehiscence of the right coronary anastomosis, and the proximal aortic anastomosis. A follow-up with an echocardiogram and computed tomography scan was found to be very useful and accurate. We thus successfully treated two cases of pseudoaneurysm using either Bentall's or Carbrol's procedures.