After valve replacement, complications occur in about 50% of all patients within the first 10 years. We differentiate between early and late complications.
Early complications include:
- Infections
- Prosthetic endocarditis (occurs in 7-15% of cases within the first 15 years; has a very poor prognosis and a high mortality [Pinger 2019])
- Bleeding
- Arrhythmias
- Heart failure
- Perioperative lung, kidney, liver, or multiorgan failure.
[Herold 2018)
Late complications include:
- Thromboembolism
- Prosthetic endocarditis
- Bleeding under anticoagulation
- Complications of prostheses:
- Tears in the sheath of valve cages
- existing disproportion of valve to body size (also called patient/ prosthesis mismatch = PPM)
- tear-out of prosthesis wings
- defects of ball prostheses
- Heart failure later in life due to:
- valve dysfunction
- occurring hypertension and / or CHD
- pre-existing myocardial damage (the pre-existing condition of the left ventricle essentially determines the long-term prognosis, especially in the case of pre-existing valvular insufficiency)
(Herold 2018)
Causes of prosthetic valve insufficiency may include:
- mechanical dysfunction (very rare, e.g., due to leaflet rupture)
- inability to close (due to thrombosis, vegetation, pannus, etc.)
- paravalvular leak / periprosthetic dehiscence (e.g. due to endocarditis, suture insufficiency, etc.)
- Degeneration of the valve (in bioprostheses).
(Pinger 2019)
Causes of prosthetic stenosis can be:
- mechanical dysfunction (very rarely occurring)
- degenerative changes (in bioprostheses)
- stenosis due to thrombus, pannus, endocarditic vegetation
(Pinger 2019)
Specific problems after valve replacement:
1. artificial valve thrombi.
The incidence of valve thrombi is under coagulation for
- the aortic valve prosthesis at 0.9 - 1.2 events / 1,000 patient-years
- The mitral valve at 2.1 - 3.4 events / 1,000 patient-years.
(Pinger 2019)
- most frequently, however, with prostheses of the tricuspid valve (exact figures are not available; patients with tricuspid stenosis receive almost exclusively biological valves because of the risk of thrombosis)
- Incidence depends on prosthesis type, rarely occurs with St. Jude Medical
(Herold 2018)
Valve insufficiency and / or stenosis with cardiac decompensation may develop as a consequence of valve thrombosis (Pinger 2019).
Clinical Symptoms:
A worsening of the clinical condition is found, signs of acute heart failure may occur, sudden cardiac arrhythmias are possible or emboli occur.
Therapy:
Prompt reoperation; lysis therapy may be required.
(Herold 2018)
In a study of 110 patients, lysis yielded success in 71% of cases. Mortality was 12% (due to both therapy failure and therapy complications [Pinger 2019].
According to Huang's 2013 expert recommendation, which included 662 operated and 756 lysed patients, thrombolysis should be the first-line therapy for right-sided thrombi. He recommended surgery only if lysis was unsuccessful.
For left-sided thrombi, Huang considers lysis to be the first-line therapy in patients
- with an absolute contraindication to surgery
- with NYHA I / II
- with comorbidities who are at high risk for surgery
- patients who refuse surgery
- with only small thrombus (< 0.8 cm² ) and no history of apoplectic insult
In turn, surgical treatment is the first choice in the following patients:
- in whom replacement of the valve prosthesis is necessary anyway
- with impaired blood flow to the coronary arteries
- with contraindication to lysis therapy
- if pannus formation contributes significantly to the obstruction
- after unsuccessful lysis therapy
Surgical intervention should initially be preferred in patients with:
- with NYHA III / IV
- thrombus size > 0.8 cm²
(Huang 2013)
2. thromboembolism
Thromboembolism occurs preferentially with the use of mechanical prosthetic valves and then predominantly in those in the mitral position, less frequently in the aortic position. The incidence is 2%-3% per patient year. Thromboembolism rarely occurs with homograft valves.
Clinical Symptoms:
Depending on the vascular territory affected (e.g., brain, extremities, intestinal vessels), ischemia is found with corresponding symptoms
(Herold 2018)
Prophylaxis:
The ACC / AHA 2014 recommends oral coagulation with Vit. K- antagonists.
Recommendation grade I:
- for mechanical aortic valve replacement (both double leaflet prosthesis and modern tilt disc prosthesis) without risk of embolism: oral anticoagulation with INR- target value 2.5
- in case of mechanical aortic valve replacement with existing risks for embolism (e.g. atrial fibrillation, left ventricular dysfunction, post-thromboembolism, hypercoagulability) or in case of older mechanical aortic valve replacement (e.g. ball-and-cage prosthesis): oral anticoagulation with INR target value 3.0
- in case of mechanical mitral valve replacement: oral anticoagulation with INR target value 3.0
Recommendation grade IIa:
- For biological mitral valve replacement or reconstruction of the mitral valve:
for the first 3 months postoperatively oral anticoagulation with INR-target 2,5
Recommendation grade IIb:
- Patients with bioprosthesis as aortic valve replacement should receive oral anticoagulation with INR- target value 2.5 for the first 3 months postoperatively
Oral coagulation with 100 mg ASA / d:
Recommendation grade I:
- In addition to oral anticoagulation with Vit. K antagonists, ALL patients with mechanical prosthesis should receive ASA.
Grade of recommendation IIa:
- all patients with bioprosthesis as aortic valve replacement or mitral valve replacement should receive ASS- continuous therapy
Grade of recommendation IIb:
- Patients with TAVI (transcatheter aortic valve implantation) should receive ASA continuous therapy and also clopidogrel in the first 6 months postoperatively;
See below for dosage recommendation.
(Pinger 2019)
Direct anticoagulants such as apixaban, edoxaban, dibagratan, rivaroxaban are contraindicated for anticoagulation in patients with artificial valves (Herold 2018).
3. prosthetic endocarditis
Prosthetic endocarditis occurs preferentially with both mechanical and biologic replacement valves. It is found less frequently only with homograft valves.
The risk of prosthetic endocarditis is about 7-15% in 15 years. The prognosis is always very serious, mortality high (Pinger 2019).
A distinction is made between early and late endocarditis.
Early endocarditis occurs within the first postoperative year and generally reflects perioperative contamination . The causative organisms are usually staphylococci and gram-negative pathogens. Only rarely are fungi the causative agent (Herold 2018).
Late endocarditis occurs only in the second postoperative year. The pathogens are identical to those that can also cause endocarditis on native heart valves such as Streptococcus aureus, Streptococcus viridans, Staphylococcus epidermidis, enterococci, etc. (Herold 2018).
Clinical Symptoms:
- Fever
- previously absent valvular murmurs
- Altered opening or closing sounds
(Herold 2018)
Diagnostics:
- transesophageal echocardiography
- a blood culture should be taken immediately (before starting antibiotics)
(Herold 2018)
Therapy:
It is recommended to start with a maximum dose combination therapy of synergistic and additive antibiotics . The duration of treatment should not be less than 6 weeks (Suttrop 2004).
Prophylaxis:
To prevent late prosthetic endocarditis, high-risk patients (which include all patients with artificial heart valves) should receive antibiotics during procedures that lead to bacteremia. Suggested dosage:
- To administer antibiotic prophylaxis as a single dose 30-60 min before the procedure;
- if oral administration is possible, amoxicillin or ampicillin 2 g p. o. can be administered
- if oral administration is not possible, ampicillin or cefalexin 2 g i.v. is recommended
- in case of ampicillin or penicillin allergy, clindamycin 600 mg should be given orally
- if i.v. administration is necessary, clindamycin 600 mg i.v.
(Herold 2018)
For more details, see endocarditis prophylaxis.
4. paravalvular leaks
Paravalvular leaks occur preferentially in the early postoperative phase on valves that have been sutured into heavily calcified valve rings. In a later phase, they usually occur in the setting of endocarditis(Herold 2018).
After aortic valve replacement, they are found in approximately 2%-10% and after mitral valve prosthesis in 7%-17% (Pinger 2019).
Paravalvular leak leads to hemolysis and regurgitation during its course (Pinger 2019).
Clinical Symptoms:
Most patients remain asymptomatic. Clinical effects of severe hemolytic anemia or signs of heart failure due to volume loading are found in only about 1%-5% (Pinger 2019).
Diagnostics;
On auscultation, reflux sounds are found at the affected valve. Laboratory chemistry indicates hemolysis (LDH, haptoglobin, reticulocytosis). A proximal zone of convergence may be present on echocardiography.
(Pinger 2019)
Therapy:
The standard therapy has been reoperation. Depending on the extent of the leak, direct suture or patch- plastic are used. The 30-day major adverse cardiatic events (MACE) is 8.7%.
Increasingly, however, percutaneous catheter-based closure systems are also being used. The mortality rate of 1.4 % - 2 % is lower than with the previous surgical procedure. Long-term data are currently lacking.
(Pinger 2019)
5. hemolysis
Mechanically induced hemolysis occurs preferentially in older valve models. It is insignificant in otherwise well-functioning prosthetic valves and is manifested only by a small increase in LDH (Herold2018).
Hemolysis is caused by high flow velocities and abnormal shear forces. A distinction is made between mild hemolysis (LDH 220 - 400 U/l). It can occur even with an intact valve.
In the case of moderate hemolysis, an LDH increase of 400 - 800 U/l is found.
From an LDH > 400 U/l, a dysfunction, such as (thrombosis, dehiscence, etc.) should be excluded.
(Pinger 2019)
As soon as valve dysfunction occurs, hemolysis increases and laboratory chemistries are detectable:
- marked LDH- elevation
- HBDH increased
- Drop in haptoglobin (is no longer measurable at all in the case of severe hemolysis)
- Hemopexin may decrease (but usually only in severe hemolysis).
- Reticulocytes are elevated
- Indirect bilirubin is also elevated
- Evidence of fragmentocytosis
- Hb-value normal or decreased (as long as the Hb-value is normal, it is a compensated hemolysis. Only when the Hb- value is decreased is it referred to as decompensated hemolysis, which is also known as hemolytic anemia).
(Herold 2018
Diagnostics:
- echocardiography should be performed to exclude prosthetic dysfunction (Herold 2018).
Therapy:
Therapy depends on the cause of hemolysis.
Conservative treatment can be used:
- Beta-blockers (reduce the flow velocity).
- Substitution of iron
- Administration of erythropoietin
(Pinger 2019)
In case of severe hemolysis, surgical revision may be necessary. A Euroscore calculator can be used on the Internet to estimate early postoperative mortality.
(Herold 2018)