Mechanical Heart Valve Implantation Research Articles

Long-Term Outcomes After TTK Chitra Mechanical Heart Valve Implantation: a 20-Year Experience of Implantation in 2272 Consecutive Patients from a Single Tertiary Centre in India

Long-Term Outcomes After TTK Chitra Mechanical Heart Valve Implantation: a 20-Year Experience of Implantation in 2272 Consecutive Patients from a Single Tertiary Centre in India

Numerical Study of Subaortic Stenosis and Pannus Formation on Blood Flow Around Mechanical Heart Valves

Patients after mechanical heart valve implantation are prone to complications. Mechanical heart valve obstruction is a rare but life-threatening complication. Obstruction may include thrombosis, pannus formation around the valve, or both. However, the relationship between thrombus and pannus and mechanical heart valve hemodynamics has not been thoroughly studied. We studied the fluid dynamics of thrombus and pannus formation through numerical simulations and provided detailed information about the interaction between complications and related prosthetic valves so that complications can be detected early. Studies have shown that the formation of thrombus and pannus leads to significant changes in the peak transvalvular velocity of the artificial valve, the transvalvular pressure gradient, and the corresponding hemodynamic indicators. As the height of the thrombus and pannus increases, the jet velocity and transvalvular pressure gradient will increase accordingly. When obstruction exceeds 20%, the impact increases significantly under the same percentage of obstacles. When the obstruction percentage is over 30%, the rest at least doubled. The results also indicate that SAS obstruction has the most significant impact on the blood flow of MHV. At the same time, it should be noted that when SAS and pannus are combined, the ring form vortex in front of the pannus has a potential risk of accelerating the deterioration of the pannus.

Comparative Evaluation of Mortality and Hemodynamic Performance Between ATS and ST JUDE Mechanical Heart Valves in Mitral and Aortic Positions

Background: Rheumatic heart disease is the most common heart disease in Asian countries especially in Afghanistan, the age adjusted death rate for this heart disease is 27,57 per 100 000 people as published by data of the World Health Organization (WHO). ST JUDE mechanical heart valve first time implanted in October 1977 and quickly became the gold standard for subsequent valves, and ATS medical international developed a mechanical heart valve that has been in use since 1992, these mechanical heart valves started implantation in Afghanistan during 2012. We presented a result of 148 patients who have undergone valve replacement in mitral and aortic position with ATS and ST JUDE mechanical heart valves at departments of cardiothoracic and vascular surgery amiri medical complex and global medical complex heart institute Kabul Afghanistan. Method and results: we performed ATS and ST JUDE mechanical heart valve replacement in 148 patients between May 2015 and April 2018 at both the Department of Cardiothoracic and Vascular Surgery Global Medical Complex heart institute and Amiri Medical Complex, Kabul Afghanistan. Male patients were 69 (46.6%) and female patients were 79 (53.3%), age range was between 11-65 years, 94 (63.5%) patients under went mitral valve replacement, for 38 (25.6%) patients performed aortic valve replacement and 16 (10.8%) patients required double valve replacement, overall mortality was 16 (10.8%) patients for mitral, aortic and double valve replacement. The early mortality (hospital mortality) was 4.05% and late mortality during a 3 year follow up was 6.7%. Conclusion: there were seen a few prosthetic valve complications after ATS and ST JUDE mechanical heart valve implantation (total number of implanted ATS mechanical heart valve were 70 and total number of implanted ST JUDE mechanical heart valve were 78), early mortality was (hospital mortality) 6 patients (4.05%) and late mortality during a 3 year follow up was 10 patients (6.7%). The international normalized ratio (INR) was maintained between (2.5-3.5) in both ATS and ST JUDE mechanical heart valves for mitral position and (2-3) for aortic position, hemodynamically ATS and ST JUDE mechanical heart valves are very good regarding trans valvular gradient and function but low prosthetic valve noise is just seen in ATS mechanical heart valve.

Numerical investigation on the effect of bileaflet mechanical heart valve's implantation tilting angle and aortic root geometry on intermittent regurgitation and platelet activation.

Platelet activation induced by shear stresses and non-physiological flow field generated by bileaflet mechanical heart valves (BMHVs) leads to thromboembolism, which can cause fatal consequences. One of the causes of platelet activation could be intermittent regurgitation, which arises due to asynchronous movement and rebound of BMHV leaflets during the valve closing phase. In this numerical study, the effect of intermittent regurgitation on the platelet activation potential of BMHVs was quantified by modeling a BMHV in the straight and anatomic aorta at implantation tilt angles 0°, 5°, 10°, and 20°. A fully implicit Arbitrary Lagrangian-Eulerian-based Fluid-Structure Interaction formulation was adopted with blood modeled as a multiphase, non-Newtonian fluid. Results showed that the intermittent regurgitation and consequently the platelet activation level increases with the increasing implantation tilt of BMHV. For the straight aorta, the leaflet of the 20° tilted BMHV underwent a rebound of approximately 20° after initially closing, whereas the leaflet of the 10°, 5°, and 0° tilted BMHVs underwent a rebound of 8.5°, 3°, and 0°, respectively. For the anatomic aorta, the leaflet of the 20° tilted BMHV underwent a rebound of approximately 24° after initially closing, whereas the leaflet of the 10°, 5°, and 0° tilted BMHVs underwent a rebound of 14°, 10°, and 7°, respectively. For all the implantation orientations of BMHVs, intermittent regurgitation and platelet activation were always higher in the anatomic aorta than in the straight aorta. The study concludes that the pivot axis of BMHV must be implanted parallel to the aortic root's curvature to minimize intermittent regurgitation and platelet activation.

Pregnant woman survives aortic dissection, dies later of coronary embolism - a unique case of a non-compliant patient

Introduction. The incidence of aortic dissection ranges 3?5 cases per 100,000 person-years. In women under the age of 40 who acquire aortic dissection, almost half of the cases happen during pregnancy. Case outline. We report a case of a 22-year-old pregnant woman in the 16th gestational week with a history of arterial hypertension and known aortic dilatation, who was admitted with aortic dissection. She underwent the Bentall procedure, in which her aortic valve, ascending aorta, and proximal part of the aortic arch were replaced using valved composite graft. On the next day, the evacuation abortion was made, since the fetus didn?t survive the operation. Six years later, the patient stopped taking anticoagulation therapy and was admitted for prosthetic valve thrombosis, which was successfully treated with intravenous heparin. One year later, the patient died of a myocardial infarction due to coronary thromboembolism, confirmed on autopsy. Conclusion. Preconceptional counseling in women with a known aortic disease is of the utmost importance. Aortic dissection in pregnant women is an acute life-threatening condition for both mother and fetus that should be managed by a multidisciplinary team. After a mechanical heart valve implantation, lifetime oral anticoagulants are mandatory.

Mechanical Heart Valve Replacement in a Low-Middle Income Region in the Modern Era: Midterm Results from a Sub-Saharan Center

The management of patients with mechanical heart valves remains a major concern in populations with limited resources and medical facilities. This study reports the clinical outcomes of patients who underwent mechanical valve implantation in a sub-Saharan center over an 8-year period. A total of 291 mechanical valves were implanted in 233 patients in our institution between February 2008 and June 2016. A total of 117 patients underwent mitral valve replacement (MVR, 50.2%), 57 had aortic valve replacement (AVR, 24.4%), and 59 underwent both AVR and MVR (double valve replacement [DVR], 25.7%). The mean age at surgery was 27.6 ± 13.4 years (range, 7-62 years). Rheumatic etiology was found in 80.6% of the patients. Hospital mortality, late deaths, and valve-related events were reviewed at follow-up (839 patient-years, range: 1-9.4 years, complete in 93%). The 30-day mortality was 4.7% (11/233). The overall survival at 1 and 6 years for the whole cohort was 88.8 ± 2.1% and 78.7 ± 3.3%, respectively. The 6-year survival for AVR, MVR, and DVR was 89.3 ± 4.8%, 73.2 ± 5.4%, and 79.3 ± 5.8%, respectively (p = 0.15). The freedom from neurologic events and anticoagulation-related bleeding at 6 years was 93.1 ± 2.1% and 78.9 ± 3.7%, respectively. No patient had reoperation at follow-up. No case of prosthetic valve thrombosis was identified. Eight full-term pregnancies were reported. This preliminary experience reports acceptable midterm results after mechanical heart valve implantation in our region. Both accurate surgical evaluation and strategies, either financial or social, facilitating patient's education and medical assistance are crucial to ensure good results. Long-term follow-up and further studies comparing current nonthrombogenic options are warranted to draw reliable conclusions.

Anticoagulant bridging in left-sided mechanical heart valve patients

BackgroundIn preparation for an invasive procedure with a high bleeding risk, patients with a mechanical heart valve temporarily have to discontinue their anticoagulant therapy and are usually bridged with either intravenous unfractionated heparin (UFH) or subcutaneous low-molecular-weight heparin (LMWH). In this study we retrospectively analyzed the safety of UFH versus LMWH as bridging strategy in left-sided mechanical heart valve patients. MethodsWe performed a retrospective multicenter study in four surgical centers in The Netherlands. Patients with a mechanical heart valve implantation bridged from January 2010 until January 2015 were included. The cumulative incidence of adverse events in the 30days following the procedure was recorded. Main outcomes were major bleeding according to International Society on Thrombosis and Haemostasis (ISTH) criteria, symptomatic thromboembolism, and mortality. ResultsIn total, 238 (174 aortic, 42 mitral, 22 aortic+mitral) bridging episodes were included. The incidence of major bleeding was 16 (19%) events in the UFH group versus 29 (19%) events in the LMWH group (p=0.97). Incidences of thromboembolism were 2 (2.4%) versus 1 (0.6%). The incidence of death was 1 (1.2%) patient in the UFH group versus 3 (1.9%) patients in the LMWH group. More than 50% of all bleeding complications were categorized as a major bleeding. ConclusionsBridging anticoagulation in patients with aortic and mitral mechanical valves is associated with considerable risk, but no difference was apparent between UFH and LMWH strategy. The rate of thromboembolism and death was low with either strategy and the vast majority of adverse events were bleedings.

Warfarin treatment quality and prognosis in patients with mechanical heart valve prosthesis

ObjectivesTo study the impact of time in therapeutic range (TTR) and international normalised ratio (INR) variability on the risk of thromboembolic events, major bleeding complications and death after mechanical heart...

Early postoperative bridging anticoagulation after mechanical heart valve replacement: a systematic review and meta‐analysis

To perform a systematic review and meta-analysis of studies evaluating anticoagulation during the early postoperative period following mechanical heart valve implantation. Five literature databases were searched to assess the rates of bleeding and thromboembolic events among patients receiving oral anticoagulation (OAC), both with and without bridging anticoagulation therapy with unfractionated heparin (UFH) or subcutaneous low molecular weight heparin (LMWH). The studies' results were pooled via a mixed effects meta-analysis. Heterogeneity (I(2) ) and publication bias were both evaluated. Twenty-three studies including 9534 patients were included. The bleeding rates were 1.8% (95% confidence interval CI1.0-3.3) in thegroup receiving OAC, 2.2% (95%CI0.9-5.3) in the OAC+UFH group, and 5.5% (95%CI2.9-10.4) in the OAC+LMWH group (P=0.042). The thromboembolic event rate was 2.1% (95%CI1.5-2.9) in the group receiving OAC, as compared with 1.1% (95%CI0.7-1.8) when the bridging therapy groups were combined as follows: OAC+UFH and OAC+LMWH (P=0.035). Most of the analyses showed moderate heterogeneity and negative test results for publication bias. Bridging therapy following cardiac valve surgery was associated with a lower thromboembolic event rate, although the difference was small, with considerable overlap of the CIs. Direct comparisons are missing. Bridging therapy with UFH appears to be safe; however, this observation has a risk of bias. Early bridging therapy with LMWH appears to be associated with consistently high bleeding rates across multiple analyses. On the basis of the quality of the included studies, more trials are necessary to establish the clinical relevance of bridging therapy and the safety of LMWH.

Valve-related complications after mechanical heart valve implantation.

The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7–3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4–1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

Dabigatran increased bleeding and stroke compared with warfarin after mechanical heart valve implantation

Source Citation Eikelboom JW, Connolly SJ, Brueckmann M, et al; RE-ALIGN Investigators. Dabigatran versus warfarin in patients with mechanical heart valves. N Engl J Med. 2013;369:1206-14. 23991661

New Anticoagulants in Cardiac Surgery

Antiplatelet and anticoagulant therapy is a key part of the management of patients undergoing cardiac surgery and one of the cornerstones to prevent complications after coronary bypass or valvular heart surgery. The use of anticoagulants and antiplatelets is life-saving, but these agents also contribute to the risk of bleeding. The only orally active anticoagulants that are licensed for long-term use are vitamin K antagonists (VKAs), such as warfarin and are often prescribed after mechanical heart valve implantation or in case of atrial fibrillation. Bleeding is a significant adverse event. Another major drawback of warfarin is the need for routine coagulation monitoring and even with monitoring, the international normalised ratio is frequently outside the therapeutic range. Development of new antithrombotic drugs has been targeted to improve the clinical benefit by reducing bleeding and thromboembolic complications and improving the ease of use. The many limitations of VKAs have provoked the development of new oral anticoagulants. Recently, dabigatran etexilate and ticagrelor have been introduced as possible substitutes. Furthermore, agents are evaluated to treat patients with acute coronary syndromes. Clopidogrel is often used, but this increases the risk of bleeding in patients in which coronary artery bypass grafting is necessary. This review outlines the alternatives of warfarin and clopidogrel therapy for patients with a mechanical heart valve or who undergo bypass surgery. It also establishes a five-year view for key contenders to replace the existing standard therapy.

Thrombogenic Performance of a St. Jude Bileaflet Mechanical Heart Valve in a Sheep Model

The sheep model is preferred for chronic evaluation of prosthetic heart valves, surgical techniques, and endocardiographic studies. A bileaflet mechanical heart valve (MHV) was implanted into a sheep model to study its in vivo performance and to evaluate the thrombogenic potential of the valve. Transesophageal echocardiography and transcranial Doppler ultrasonography measurements were conducted before and after the valve implantation. Platelet activity state (PAS) assay measurements were also conducted before and after the implantation surgery. After sheep euthanasia, the MHV was explanted and scanning electron microscopy (SEM) was performed on the explanted valve to examine changes to the MHV surface. Tissue blocks were taken from the sheep brain, left ventricle, aorta, spleen, and lung lobes for histological examination. Our results indicated that after the MHV implantation, more embolic signals were detected in the sheep carotid artery, increasing monotonously as a function of implantation time. Echocardiographic parameters including blood aortic velocity, transvalvular pressure gradient, and velocity time integral increased. PAS increased significantly after valve implantation. SEM pictures demonstrated calcium and phosphate deposition on the valve surfaces. Histological examination demonstrated hemorrhage in the lung tissue, pulmonary thrombosis, and osteogenesis in heart tissue.

Use of prothrombin fragment 1+2 for evaluating anticoagulant therapy after mechanical heart valve replacement

Prothrombin fragment 1+2 (F1+2) is a coagulation factor newly used as a molecular marker to monitor anticoagulant therapy in patients undergoing heart valve replacement. We evaluated the usefulness of F1+2 against that of prothrombin time (PT) reported as the internationalized normalized ratio (INR) in 93 patients undergoing mechanical heart valve implantation between August 1999 and July 2000. The study group consisted of 38 men and 55 women, with an average age of 61.1±11.2 years. The surgeries were 34 aortic replacements, 9 double valve replacements, and 50 mitral valve replacements. Warfarin doses were controlled based on PT-INR values at a target range of 1.5–2.5 F1+2 levels in the 0.4–1.2 nmol/l level were considered normal. No thromboembolism or bleeding complication occurred in any patient during the mean follow-up period of 12 months. The overall correction coefficient between F1+2 and PT-INR was 0.165 (P 2.50 were less than half of the lower limit of normal. Our analysis involving F1+2 confirmed PT-INR in the 1.5–2.5 range following mechanical heart valve implantation to be optimal. We found that using F1+2 to monitor individual response to anticoagulation therapy is useful when PT-INR values are difficult to obtain.

Platelets are deposited early post-operatively on the leaflet of a mechanical heart valve in sheep without post-operative anticoagulants or antiplatelet agents. A scanning electron microscopic observation of the pyrolytic carbon surface in a mechanical heart valve.

Pyrolytic carbon has been used for mechanical heart valves as a thromboresistant, wear resistant, and fatigue resistant material. Thrombosis and thromboembolism, however, remain major mechanical heart valve associated complications and may frequently occur during the early post-operative period. In depth morphologic studies on blood-pyrolytic carbon surface interactions are limited. The purpose of this study was to evaluate the blood compatibility of the pyrolytic carbon surface of St. Jude Medical mechanical heart valves that were implanted in the mitral position of sheep without the administration of post-operative anticoagulants or antiplatelet agents for 2, 4, and 6 weeks. Almost the entire leaflet and orifice ring surfaces were observed by scanning electron microscopy. Although the surfaces appeared clean macroscopically, when observed by electron microscopy, the surface were mottled, mainly by solitary platelets and aggregations. There were only a few leukocytes or red blood cells observed. No fibrin clots were observed on the leaflets. The density of platelet deposition was higher in the vicinity of the pivots and near the edges of the leaflets. The sizes of the platelet aggregations decreased with longer duration. The outer surfaces of the pivot guards were covered by various amounts of deposition composed of platelet aggregations and thrombi. Thus, the administration of antiplatelet agents is recommended during the early post-operative period after mechanical heart valve implantation.

Impact of mechanical heart valve prosthesis sound on patients' quality of life

The "click" sound of mechanical heart valve prostheses has been recognized as a disturbing factor for some patients after mechanical heart valve implantation. The factors determining the extent of disturbance remain controversial. Ninety-five unmatched patients with six different valve types were examined (Duromedics-Edwards, Björk-Shiley, St. Jude Medical, Medtronic, CarboMedics, and Omnicarbon), including 12 patients with double-valve replacement. Three groups (Björk-Shiley, Duromedics-Edwards, and St. Jude Medical) were comparable in size. All patients were examined and interviewed, a hearing test was performed, and valve sounds were analyzed. Sound transmission was evaluated. The loudest valve was the Duromedics-Edwards prosthesis (mean, 84.2 dB[A] impulse) and the St. Jude Medical was the quietest (mean, 73.5 dB[A] impulse). This ranking was independent of patient variables and valve position. Discomfort level correlated with hearing loss and loudness of the valve. Patients desiring a quieter valve had better hearing, had louder valve sounds, felt disturbed by the sound, had partners who felt disturbed, and were receiving coumarin for anticoagulation. Sound was transmitted predominantly by air conduction. The frequency analysis to identify different valves was unsatisfactory, but louder frequencies did correspond with hearing-impaired patients' audiograms. Our results emphasize the need for valve design changes, preoperative education about the sound, and inclusion of routine hearing tests into the preoperative workup.

Transcranial Doppler “High Intensity Transient Signals” in the acute phase and long-term follow-up of mechanical heart valve implantation

Patients have a significant risk for suffering from stroke caused by cardiac emboli following prosthetic valve implantation. It is known that cerebral emboli present with "high intensity transient signals" (HITS) in transcranial Doppler (TCD) spectral curves. The purpose of this research was to look for possible HITS in the acute phase and long-term follow-up of mechanical heart valve implantation with TCD to correlate the number of HITS with clinical symptoms and to find parameters associated with an increase or decrease in HITS in patients with prosthetic heart valves. We examined the frequency of HITS after mechanical valve replacement with TCD in the left middle cerebral artery (MCA) for a period of 15 min. A total of 179 patients were investigated. One-hundred patients were examined at intervals between 1 and 33 days (Group 1) and 79 patients between 10 and 13 months (Group 2) after valve replacement. These data were correlated with neurological deficits and hematological parameters. In Group 1, at least one HITS could be detected by TCD in 65 patients (65%). There were no differences between sexes or in valve location, heart rhythm, and thromboplastin time between patients with and without HITS. The prevalence of HITS in valve types other than St. Jude and Medtronic Hall was significantly higher (p = 0.004). Ninety-three of the patients in Group 1 were neurologically asymptomatic; seven patients suffered from a hemispheric deficit after valve implantation. The neurologically symptomatic patients presented with a significantly higher HITS rate (10.9 ± 8.3; mean ± SD) than the neurologically asymptomatic patients (4.4 ± 12.3). One year after surgery (Group 2), the prevalence of HITS was 77%. The number of HITS in Group 2 was significantly higher than in Group 1 (p = 0.003). Following valve replacement, patients present with a high frequency of HITS. Symptomatic patients have a significantly higher rate of HITS than asymptomatic patients in the acute postoperative period. Thus, TCD examination may be used as an additional method to evaluate the individual risk for cerebral ischemia in the acute phase of heart valve implantation.