Valves replacing

Implantable valves, particularly mechanical valves which continue to encroach on tissue valves, are unique. Methods such as valvuloplasty, mitral valve repair, or use of ultrasound are unlikely to reduce the number of valve replacements into the twenty-first century. Valve selection remains in the hands of the surgeon because of the critical nature of the procedure. If anything goes wrong, the result can be catastrophic to the patient. Cost of a valve, from 3000— 4000, is a relatively small part of the cost of open-heart surgery which can mn as high as 30,000. Growth of the cardiovascular valve market has slowed in the United States with the decline of the threat of rheumatic fever. 

Ball valves in which the ball and seats are inserted from above are known as top-entry ball valves. Replacement of seats is easiest in this... 

Some vessels are provided with two full-size relief valves so that one can be changed with the plant on line. On the plant side of the relief valves, isolation valves are usually provided below each relief valve, interlocked so that one relief valve is always open to the plant (Figure 10-2). If the relief valves discharge into a flare system, it is not usual to provide such valves on the flare side. Instead the relief valve is simply removed and a blank fitted quickly over the end of the flare header before enough air is sucked in to cause an explosion. Later the blank is removed and the relief valve replaced. 

Hotter and Balannec published one of the first real proposals to use SMB as a production tool for the pharmaceutical industry, and thus to scale down a process already used on a production scale [29]. The first commercially available plant (Licosep) SMB system was offered by Separex in 1991 and was exhibited for the first time in June 1991 during the Achema Exhibition. The system consisted of 24 stainless steel columns with adjustable lengths between a few centimeters up to almost 1 meter, HPLC pumps, and mulitpositional valves. To improve the robustness of the system, a rotary valve replaced two-way valves and the pumps were modified. 

Prevention of thrombus formation after valve replacement... 

Warfarin has been the primary oral anticoagulant used in the United States for the past 60 years. Warfarin is the anticoagulant of choice when long-term or extended anticoagulation is required. Warfarin is FDA-approved for the prevention and treatment of VTE, as well as the prevention of thromboembolic complications in patients with myocardial infarction, atrial fibrillation, and heart valve replacement. While very effective, warfarin has a narrow therapeutic index, requiring frequent dose adjustments and careful patient monitoring.15,29... 

These complications primarily are due to the presence of large, friable vegetations and numerous emboli and the development of acute congestive heart failure that often requires valve replacement.31,32 It is important to allow cultures sufficient incubation time (often 2-3 weeks) in order to isolate these organisms. Often these organisms may not be isolated on culture and thus present as culture-negative IE. 

Gram-negative IE typically has a poor prognosis with high mortality rates (as high as 83%). Treatment usually consists of high-dose combination therapy, with valve replacement often a necessity in many patients. 

Treatment of fungal IE is exceptionally difficult. There is a significant lack of studies to identify and recommend the most appropriate therapy. Currently, amphotericin B is the most common treatment. However, valve replacement surgery is often considered an adjunct therapy. Intravenous antifungal therapy requires high doses for a minimum of 8 weeks of treatment. Oral azoles (e.g., fluconazole) are used as long-term suppressive therapy to prevent relapse. The exact role of some... 

Surgical intervention has become an integral therapy in combination with pharmacologic management of IE. Valve replacement is the predominant intervention, and it is used in a minimum of 25% for all cases of IE.1 Surgery may be indicated if the patient has unresolved infection, ineffective antimicrobial therapy (often associated with fungal IE), more... 

KVO Keep vein open MVR Mitral valve replacement mitral valve regurgitation... 

Surgery is an important adjunct to management of endocarditis in certain patients. In most cases, valvectomy and valve replacement are performed to remove infected tissues and restore hemodynamic function. The most important indications for surgical intervention in the past have been heart failure in left-sided IE and persistent infections in right-sided IE. 

S. aureus has become more prevalent as a cause of endocarditis because of increased IV drug abuse, frequent use of peripheral and central venous catheters, and valve-replacement surgery. Coagulase-negative staphylococci (CNST, usually S. epidermidis) are prominent causes of PVE. 

Tetracycline 500 mg every six hours or doxycycline 100 mg every twelve hours for five to seven days will shorten the duration of illness, and fever usually disappears within one to two days after treatment is begun. Ciprofloxacin and other quinolones are active in vitro and should be considered for victims unable to take tetracycline or doxycycline. Successful treatment of Q fever endocarditis is much more difficult. Tetracycline or doxycycline given in combination with trimethoprim-sulfamethoxazole (TMP-SMX) or rifampin for twelve months or longer has been successful in some cases. However, valve replacement is often required to achieve a cure. 

Dipiridamol is known as a coronary vasodilating agent, although it also possesses specific antiaggregant activity. It is used for preventing thrombo-formation after cardiac valve replacement in combination with warfarin. The mechanism of dipiridamoTs antiaggregant action is not completely clear, and its efficacy is questionable. 

Patients at greatest risk for developing potassium chloride-induced Gl lesions include The elderly, the immobile and those with scleroderma, diabetes mellitus, mitral valve replacement, cardiomegaly, or esophageal stricture/compression. 

Thromboembolic complications Adjunct to coumarin anticoagulants in the prevention of postoperative thromboembolic complications of cardiac valve replacement. 

Adjunctive use in prophylaxis of thromboembolism after cardiac valve replacement The recommended dose is 75 to 100 mg 4 times/day as an adjunct to the usual warfarin therapy. 

Adverse reactions at therapeutic doses are usually minimal and transient. With long-term use, initial side effects usually disappear. The following reactions were reported in 2 heart valve replacement trials comparing dipyridamole and warfarin therapy to either warfarin alone or warfarin and placebo dizziness, abdominal distress, headache, and rash. 

Prophylaxis and/or treatment of the thromboembolic complications associated with atrial fibrillation and/or cardiac valve replacement. 

Unlabeled uses Hydralazine in doses up to 800 mg 3 times/day has been effective in reducing afterload in the treatment of congestive heart failure (CHF), severe aortic insufficiency, and after valve replacement. 

Since arterial emboli formation involves platelet aggregation and leukocyte and erythrocyte inhltration into the fibrin network, the treatment and prophylaxis of arterial thrombi are more difficult. Arterial embolism is treated more successfully with heparin than with the oral anticoagulants. Anticoagulants are useful for prevention of systemic emboli resulting from valvular disease (rheumatic heart disease) and from valve replacement. 

Cardiopulmonary bypass, with extracorporeal circulation during cardiac artery bypass graft or heart valve replacement surgery, causes transient hemostatic defects in blood cells and perioperative bleeding. The protease inhibitor aprotinin (Trasylol) inhibits kalhkrein (coagulation phase) and plasmin (hbrinolysis) and protects platelets from mechanical injury. The overall effect after infusion is a decrease in bleeding. 

Unlabeled Uses Mitral valve replacement, myocardial infarction... 

Ginseng (41) (Ginsana ) capsules t.i.d. for 2 wks Male/47 Heart valve replacement Warfarin 5 mg/d for 5 yrs 7.5 mg each Tuesday Diltiazem, nitroglycerin, salsalate Decreased INR (from about 3.3 to 1.5) Not known... 

Finally, aspirin has also been used to prevent thrombus formation in peripheral veins (deep vein thrombosis [DVT]), and aspirin is sometimes used as an adjunct or alternative to anticoagulants (heparin, warfarin) that are routinely used to treat DVTs.8 Aspirin can likewise be administered to prevent thromboembolism following surgical procedures such as coronary artery bypass, arterial grafts, endarterectomy, and valve replacement 45,78 By preventing platelet-induced thrombogenesis, aspirin helps maintain patency and prevent reocclusion of vessels following these procedures. 

Cribier A, Savin T Saoudi N, et al. Percutaneous transluminal valvuloplasty of acquired aortic stenosis in elderly patients an alternative to valve replacement Lancet 1986 I (8472) 63-67. 

Dipyridamole is an adenosine reuptake inhibitor and a phosphodiesterase inhibitor with antiplatelet and vasodilating activity. As a result, the compound is therefore used in thrombo-imbolic disorders. Orally administered dipyridamole is used in association with orally administered anticoagulants for the prophylactic treatment of thromboimbolism following cardiac valve replacement. It is also used as a coronary vasodilator [5-8]. 

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