Approach Considerations
In patients with acute valvular failure, diagnostic studies must be performed simultaneously with resuscitative efforts.
Initiate arrangements for transfer to a center with cardiac surgical capabilities in patients presenting with moderate-to-severe hemodynamic compromise if these services are not readily available.
Mortality in patients with acute prosthetic valvular failure is directly related to delay of surgical correction.
Emergency Department Care
Primary valve failure
Patients with valvular failure due to breakage or abrupt tearing of the components usually present with acute hemodynamic deterioration. These patients require emergent valve replacement. Adjunctive therapy may be initiated while such arrangements are being made. A less dramatic presentation of valvular failure may be seen in patients with valve thrombosis or in those with more gradual deterioration of bioprosthetic valves (see "Thromboembolic complications," below).
Depending on which prosthetic valve has failed will determine which treatment strategy to pursue. Inotropes are helpful in the setting of depressed left ventricular ejection fraction or right ventricular dysfunction in the setting of left-sided acute valve failure. Dobutamine can be used for inotropic properties, but keep in mind there is an increased risk of arrhythmias. Norepinephrine can also be used for hemodynamic support and has some inotropic properties as well; however, it comes with the drawback of increasing afterload. In all left-sided valve failures, afterload reduction can be achieved medically with nitroprusside. [25] Begin afterload reduction and inotropic support to reduce the impedance to forward flow and improve peripheral perfusion. If the mean arterial pressure is higher than 70 mmHg, sodium nitroprusside may be used. If the mean arterial pressure is lower than 70 mmHg, inotropes may be used.
Avoid inotropic agents with vasoconstricting properties.
Intra-aortic balloon pumps are particularly helpful in the setting of acute mitral regurgitation and can mechanically assist with afterload reduction. These devices can also be used for afterload reduction in aortic stenosis. Note that intra-aortic balloon pumps are contraindicated in the setting of aortic regurgitation. [25]
Prosthetic valve endocarditis
The standard to diagnose infective endocarditis relies on the Modified Duke Criteria, which incorporates clinical, imaging, and bacteriological criteria. [12]
Administer intravenous antibiotics as soon as two sets of blood cultures are drawn. Vancomycin and gentamicin may be used empirically pending blood culture results and the determination of methicillin resistance.
Patients taking a vitamin K antagonist (VKA), such as warfarin, who develop prosthetic valve endocarditis (PVE) should stop taking the VKA until central nervous system (CNS) involvement is ruled out and invasive procedures are determined to be unnecessary. [4]
Consider anticoagulation in PVE, as the incidence of systemic embolization is as high as 40%.
Consider emergency surgery in patients with moderate-to-severe heart failure or in patients with an unstable prosthesis noted on echocardiography or fluoroscopy.
Thromboembolic complications
Patients presenting with embolization need to be anticoagulated if they are not already taking anticoagulants or have a subtherapeutic international normalized ratio (INR). It is important to document the type of anticoagulant therapy used and the duration on treatment spent in the therapeutic range. It is also important to rule out other potential causes of embolization, such as infective endocarditis, new-onset atrial fibrillation, and excluding other hypercoagulable states, if clinically suspicious. [12]
Assessment of valve function is needed when prosthetic thrombosis is suspected. Urgent evaluations with transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), fluoroscopy, cardiac computed tomography (CT) scanning, or cardiac magnetic resonance imaging (CMRI) is necessary to assess valve function, leaflet motion, and the presence of the thrombosis as well as its extent. [12]
The RE-ALIGN trial (Randomized, Phase II Study to Evaluate the Safety and Pharmacokinetics of Oral Dabigatran Etexilate in Patients after Heart Valve Replacement) evaluated the safety and efficacy of dabigatran in patients with bileaflet mechanical prosthetic heart valves (recently implanted or implanted >3 months prior to enrollment) who were randomized to dose-adjusted warfarin or dabigatran 150, 220, or 300 mg twice daily. The study was terminated early due to the occurrence of significantly more thromboembolic events and excessive major bleeding with dabigatran compared with warfarin. These data resulted in revision of the US dabigatran prescribing information to include a contraindication in patients with mechanical prosthetic valves. [26]
Prosthetic valve thrombosis
Note the following:
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Surgery had historically been the mainstay of treatment of prosthetic valve thrombosis, but it is associated with a high mortality rate.
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Mortality of 18% has been reported in those with New York Heart Association (NYHA) class IV undergoing surgery for left-sided prosthetic valve thrombosis.
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Thrombolytic therapy may be used to treat select patients with thrombosed prosthetic valves.
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Thrombolytic therapy is currently recommended over surgery for right-sided prosthetic valve thrombosis. [4]
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Thrombolytic therapy is recommended over surgery for small left-sided prosthetic valve thrombosis (thrombus area < 0.8 cm2). The use of heparin and serial echocardiography is also recommended in these cases to documents improvement and thrombus resolution. [4]
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Thrombolytic therapy is recommended in large (=0.8 cm2) left-sided prosthetic valve thrombosis when contraindications to surgery are present. [4]
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Contraindications to thrombolysis of left-sided prosthetic valve thrombosis include the presence of a large left atrial thrombus, ischemic CVA between 4 hours and 4-6 weeks ago, and very early postoperative state (< 4 d). [27]
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Thrombolytic therapy should always be done in conjunction with cardiovascular surgical consultation.
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Patients with major anticoagulant-related hemorrhage require reversal of their anticoagulation with fresh frozen plasma and vitamin K.
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The time off anticoagulants should be as short as possible to avoid valve thrombosis.
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Recombinant factor VIIa or prothrombin complex concentrate should not be used to reverse excessive anticoagulation in patients with prosthetic heart valves.
Based on findings from a retrospective study of 778 patients, Yaffee et al recommend extending established guidelines for blood conservation strategy (BCS) in routine cardiac surgeries to aortic valve replacement. [28, 29] The investigators reported that implementing BCS (eg, limits on intraoperative hemodilution, tolerance of perioperative anemia, blood management education of the cardiac surgery team) may reduce the use of red blood cells (RBCs) during surgery—without increasing mortality or morbidity. [28, 29]
In their study, implementation of the strategy resulted in a 2.7-fold reduction in RBC transfusions as well as a 1.7-fold reduction in the incidence of major complications (eg, sepsis, respiratory failure, renal failure, death). [28, 29] The incidence of RBC transfusion fell significantly from 82.9% before use of BCS to 68.0% after implementation of the strategy.
Transfusion of 2 or more units of RBC on the day of surgery was associated with mortality, prolonged intubation, postoperative renal failure, and an increased incidence of any complication. Factors that affected the risk of RBC transfusion included the following [28, 29] :
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Decreased risk: Isolated aortic valve replacement, minimally invasive approach, BCS
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Increased risk: Older age, previous cardiac procedure, female sex, smaller body surface area
Consultations
In patients presenting with any degree of prosthetic valvular failure, early consultation with a cardiologist is recommended to perform and interpret a echocardiography.
Consult a cardiothoracic surgeon early in cases of severe hemodynamic compromise.
Prevention
Provide antibiotic prophylaxis to patients undergoing procedures that may result in bacteremia. The following list, although not exhaustive, includes most inpatient and outpatient procedures performed in the emergency department that may result in bacteremia and, therefore, may lead to prosthetic valve endocarditis (PVE) [30] :
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Dental and oral procedures
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Respiratory procedures, particularly those which involve disruption of the respiratory mucosal surface, or when a known infection is present. If a known infection caused by Staphylococcus aureus is present, prophylaxis with an anti-staphylococcal penicillin, cephalosporin, or vancomycin should be given. In cases of known or suspected methicillin-resistant S aureus (MRSA), prophylaxis with vancomycin should be given.
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Sclerotherapy of bleeding esophageal varices
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Routine prophylaxis for gastrointestinal or genitourinary procedures is no longer recommended, unless in the presence of a known infection [31] : Urethral catheterization in the presence of a suspected urinary tract infection; vaginal delivery in the presence of infection
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Incision and drainage of infected tissues
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For dental, oral, or upper respiratory tract procedures, use oral (PO) amoxicillin 2 g 30-60 minutes before the procedure. If the patient is unable to take PO medication, use intramuscular (IM) or intravenous (IV) ampicillin 2 g OR cefazolin 1 g IM/IV, OR ceftriaxone 1 g IM/IV 30-60 minutes before the procedure. For penicillin-allergic patients, use clindamycin 600 mg PO/IM/IV OR azithromycin 500 mg PO OR clarithromycin 500 mg PO OR cephalexin 2 g PO 30-60 minutes before the procedure. (These are all single-dose regimens.) Do not use cephalexin in patients with a documented significant allergy to penicillin unless there is documentation that the patient can tolerate cephalosporins.
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Further guidelines on the prevention, diagnosis, and treatment of infective endocarditis are available from the American Heart Association and the European Society of Cardiology. [30, 32, 33]
Long-Term Monitoring
Following heart valve replacement, every patient should undergo a history, physical examination, and appropriate testing at the first postoperative visit (2-4 wk after hospital discharge). An echocardiographic examination should be performed at this time. Thereafter, follow-up visits are recommended annually, or earlier (with echocardiography) if new symptoms develop that are attributable to a potential valvular dysfunction. In patients with a bioprosthetic valve, annual echocardiograms may be considered after the first 5 years in the absence of any changes in clinical status. [12]
Patients with postoperative left ventricular dysfunction should be treated with standard therapy for systolic heart failure, even if improved or asymptomatic. [12]
Although the risk of thromboembolic events is lower in patients with a bioprosthetic valve than in those with a mechanical prosthesis, low-dose aspirin (75-100 mg/d) is indicated in patients without thromboembolic risk factors (eg, atrial fibrillation, previous thromboembolism, hypercoagulable condition). Although the risk of early embolic events is relatively low in patients treated with aspirin only, the addition of warfarin at hospital discharge reduces the incidence of early embolic events, but that benefit is balanced by an increased risk of repeat hospitalization for bleeding. [34] For patients with risk factors, warfarin is indicated to achieve an international normalized ratio (INR) of 2.0 to 3.0, whether after aortic valve replacement or mitral valve replacement. Alternatively, aspirin in a dose of 75-325 mg per day is indicated in patients who are unable to take warfarin.
All patients with prosthetic valves should receive antibiotic prophylaxis against infective endocarditis prior to dental procedures.
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Prosthetic Heart Valves. Medtronic Hall mitral valve. Reproduced with permission from Medtronic, Inc.
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Prosthetic Heart Valves. The Hancock M.O. II aortic bioprosthesis (porcine). Reproduced with permission from Medtronic, Inc.
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Prosthetic Heart Valves. Starr-Edwards Silastic ball valve mitral Model 6120. Reproduced with permission from Baxter International, Inc.
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Prosthetic Heart Valves. Carpentier-Edwards Duralex mitral bioprosthesis (porcine). Reproduced with permission from Baxter International, Inc.
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Prosthetic Heart Valves. Carpentier-Edwards Perimount pericardial aortic bioprosthesis. Reproduced with permission from Baxter International, Inc.
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Prosthetic Heart Valves. St. Jude Medical mechanical heart valve. Photograph courtesy of St. Jude Medical, Inc. All rights reserved. St. Jude Medical is a registered trademark of St. Jude Medical, Inc.
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Prosthetic Heart Valves. Edwards Sapien transcatheter aortic valve.
