scholarly journals Platelet Suppression Therapy in Arterial Disease: Present Status

1977 ◽  
Author(s):  
J. A. Blakely
Keyword(s):  
Secondary Prevention ◽  
Heart Valves ◽  
Case Reports ◽  
Myocardial Infarct ◽  
Arterial Disease ◽  
Preliminary Evidence ◽  
Prosthetic Heart Valves ◽  
Prosthetic Valves ◽  
Survival Studies ◽  
Cerebral Ischemic

Arterial disease is a severe test of clinical trials methodology. Results to date have defined areas for further study, but clinical indications are not established. Dipyridamole reduces emboli from prosthetic heart valves but applicability to less thrombogenic valves is uncertain. Transient cerebral ischemic attacks are physiologically appropriate and there is preliminary evidence of reduced attacks with Sulfinpyrazone, none with Dipyridamole, and favorable case reports with Aspirin. Effects on stroke and death in patients presenting with TIA or stroke are under study. Sulfinpyrazone has failed to prolong patency time after peripheral vascular surgery. Administration of aspirin and of Sulfinpyrazone to elderly populations has shown no detectable benefit from Aspirin, and has suggested that Sulfinpyrazone should be further studied in patients recovered from thrombotic stroke. The greatest potential benefit may be secondary prevention of myocardial infarct, but to date efficacy has neither been demonstrated nor excluded. Studies in progress include: ASA and/or Sulfinpyrazone and TIA, stroke and death in patients with TIA; ASA with and without Dipyridamole in patients with TIA: Sulfinpyrazone and survival after recovery from thrombotic stroke; Secondary prevention of myocardial infarct with ASA, ASA or ASA + Dipyridamole, Sulfinpyrazone, and Clofibrate; Sulfinpyrazone, ASA, and ASA with anticoagulants and emboli from prosthetic valves. Platelet survival studies may permit selection of populations likely to benefit and assessment of adequacy of therapy.Hypotheses tested by clinical trial must be distinguished from hypotheses formulated from retrospective analysis, and methods must permit effects of treatment to be distinguished from differences in risk.

scholarly journals Imaging of Cardiac Valves by Computed Tomography

Scientifica ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Gudrun Feuchtner
Keyword(s):  
Computed Tomography ◽  
Heart Valves ◽  
Severe Aortic Stenosis ◽  
Multislice Ct ◽  
Valvular Disease ◽  
Special Focus ◽  
Prosthetic Heart Valves ◽  
Cardiac Valves ◽  
Effective Treatment Option ◽  
Prosthetic Valves

This paper describes “how to” examine cardiac valves with computed tomography, the normal, diseased valves, and prosthetic valves. A review of current scientific literature is provided. Firstly, technical basics, “how to” perform and optimize a multislice CT scan and “how to” interpret valves on CT images are outlined. Then, diagnostic imaging of the entire spectrum of specific valvular disease by CT, including prosthetic heart valves, is highlighted. The last part gives a guide “how to” use CT for planning of transcatheter aortic valve implantation (TAVI), an emerging effective treatment option for patients with severe aortic stenosis. A special focus is placed on clinical applications of cardiac CT in the context of valvular disease.

scholarly journals Analysis of leaflet flutter in biological prosthetic heart valves using PIV measurements

2019 ◽  
Vol 42 ◽  
pp. e41746
Author(s):  
Artur Henrique de Freitas Avelar ◽  
Mairon Assis Guimaris Eller Stófel ◽  
Glenda Dias Vieira ◽  
Jean Andrade Canestri ◽  
Rudolf Huebner
Keyword(s):  
High Speed ◽  
Heart Valves ◽  
Particle Image ◽  
Prosthetic Heart Valves ◽  
Shear Stresses ◽  
Lower Velocity ◽  
Piv Measurements ◽  
Prosthetic Valves ◽  
Image Velocimetry ◽  
Experimental Bench

The use of biological prosthetic valves has increased considerably in recent decades since they have several advantages over mechanical ones, but they still possess the great disadvantage of having a relatively short lifetime. An understudied phenomenon is the flutter effect that causes oscillations in the cusps, which is associated with regurgitation, calcification and fatigue, which can reduce even more the lifetime of bioproteses. In an experimental bench that simulates the cardiac flow, the behavior of a porcine and a bovine pericardium valves was recorded by a high-speed camera to quantify the oscillations of the cusps and an experiment using particle image velocimetry was conducted to study the velocity profiles and shear stresses and their relations with flutter. Results showed that the pericardial valve has lower values of frequencies and amplitudes compared to the porcine valve. Lower velocity values were found in the cusps that did not have flutter, but no relationship was observed between shear stress values and leaflet vibrations. These results may assist in future projects of biological prosthetic valves that have less flutter and longer lifespan.

Current Major Trials with Antithrombotic Agents

1975 ◽  
Author(s):  
M. Verstraete
Keyword(s):  
Clinical Trials ◽  
Heart Valves ◽  
Current Knowledge ◽  
Vascular Occlusion ◽  
Arterial Disease ◽  
Prosthetic Heart Valves ◽  
Antithrombotic Agents ◽  
Vein Thrombosis ◽  
Artery Disease ◽  
Peripheral Arterial

Numerous clinical trials have been recently carried out or are being planned with antithrombotic agents. What is the current knowledge on agents affecting the platelet function: are they clinically useful? The clinical validity of anti-aggregating agents is to be demonstrated in controlled clinical trials having a vascular occlusion as the end point to judge the drug effect. A survey will be presented on the results available with one of the three agents currently available, acetylsalicylic acid, dipyridamole and sulfinpyrazone. Following clinical conditions are to be discussed separately: peripheral arterial disease, coronary artery disease, patients with prosthetic heart valves, certain renal disease, ITP, haemolytic uraemic syndrome and conditions often complicated with deep venous thrombosis.To what extent and subcutaneous heparin used in low-dosage can decrease the incidence of post-operative deep-vein thrombosis and outweight its possible disavantages is another item to be reviewed.

Development of a Test Bank for Fluid Dynamic Analysis of Two Prosthetic Heart Valves Using Air as Working Fluid

2014 ◽  
Author(s):  
Luz M. Rivera ◽  
Ana I. Crispín ◽  
Nelson Escobar ◽  
Lina M. Hoyos ◽  
John Bustamante
Keyword(s):  
Dynamic Analysis ◽  
Heart Valves ◽  
Fluid Dynamic ◽  
Structural Characteristics ◽  
Working Fluid ◽  
Prosthetic Heart Valves ◽  
Pressure Gradients ◽  
Prosthetic Valves ◽  
Hemodynamic Performance ◽  
Clinical Conditions

This work presents the fluid dynamic analysis of the mechanical prosthetic heart valves: Björk Shiley and Sorin Bicarbon™. Analysis of prosthetic valves is currently done with viscous fluids that emulate the behavior of blood; however the developed test bank, wind tunnel, uses air as the working fluid. This working fluid differs from those currently being used due to its low density and viscosity properties, which provides greater sensitivity to small changes in geometry and valve design variations. These features permit to identify relevant changes to the patient’s hemodynamic system based on the effect of the implanted valve. Tests were performed by measuring the fluid-dynamics of both valves; the obtained results show accuracy with the valves’ performance under clinical conditions. The offset design of the Björk Shiley tilting disk gives the valve the ability to generate less blood trauma and increase laminar flow and the Sorin Bicarbon™ bileaflet has a larger orifice for better hemodynamic performance. Furthermore, the transversal pressure gradients and local effects such as turbulence and vortexes were also analyzed; and the obtained results are accurate according to the functionality, geometrical and structural characteristics of both valves at their real environment.

Platelet Malondialdehyde in Cardiovascular Disease: Effect of Prosthetic Heart Valves and Cardioactive Drugs on Production

1980 ◽  
Vol 44 (02) ◽  
pp. 076-080 ◽  
Author(s):  
Jay M Sullivan ◽  
J Charles Taylor ◽  
Joseph K Samaha ◽  
Patti Lamar ◽  
Darrell R Patrick ◽  
...  
Keyword(s):  
Heart Valves ◽  
Platelet Rich Plasma ◽  
Blood Platelets ◽  
Normal Subjects ◽  
Serum Levels ◽  
Multiple Drug ◽  
Prosthetic Heart Valves ◽  
Prosthetic Valves ◽  
Enhanced Production ◽  
Platelet Survival

SummaryMalondialdehyde (MDA), a product of platelet lipid peroxidation, was measured in human platelet-rich plasma. Levels of 3.19 n moles/109 platelets ± 0.40 S.E. in 11 patients with prosthetic heart valves were elevated (p<0.25) compared to 17 normal subjects (2.09 ± 0.13 n moles/109 platelets). Reduced production (1.44 ± 0.28 n moles/109 platelets, p<0.5) was found in 10 patients with unstable angina. Normal levels were found in patients with mitral stenosis, cardiomyopathy or hypertension. Usual serum levels of drugs used in cardiac treatment reduced MDA levels as follows: acetaminophen, 47% (p<.01); aspirin, 58% (p<.05); furosemide, 32.6% (p<.005), and sulfinpyrazone, 41% (p<.05). Digoxin, dipyridamole, heparin, hydrochlorothiazide, lidocaine, nitroglycerin, procainamide, propranolol, quinidine, or warfarin had no significant effect at therapeutic concentrations. None of the drugs explained the enhanced production in patients with prosthetic valves while analgesic therapy could explain the decreased levels in other cardiacs. The half-time of platelet survival, measured by suppression of malondialdehyde production, was 3.2 ± 0.24 days in 9 normal subjects but could not be measured reliably in most patients because of multiple drug therapies. We conclude that the blood platelets of patients with prosthetic heart valves differ from those of normal subjects in their capacity to release malondialdehyde after stimulation with n-ethylmaleimide. Additionally, we find that inhibition of malondialdehyde production by several pharmacologic agents limits the usefulness of this method for the measurement of platelet survival in cardiac patients.

Effect of Suloctidil on Shortened Platelet Regeneration Time in Cardiovascular Patients

1979 ◽  
Author(s):  
R Deperon ◽  
R Roncucci ◽  
G Lambelin ◽  
J Lansen ◽  
F Van Stalle
Keyword(s):  
Heart Valves ◽  
Placebo Treatment ◽  
Arterial Disease ◽  
Prosthetic Material ◽  
Prosthetic Heart Valves ◽  
Double Blind ◽  
Vasoactive Agent ◽  
Regeneration Time ◽  
Occlusive Vascular Disease ◽  
Number Of Patients

Previous investigations based on the measurement of platelet regeneration time (PRT) rather than platelet survival time (PST) have suggested that this parameter is significantly reduced in patients bearing vascular prosthetic material and in a number of patients with occlusive vascular disease (1). Since it is well-known that shortened PST can be normalized by antiplatelet drug’s, it seemed interesting to investigate whether the measurement of PRT could also detect this effect. Suloctidil (S), a new vasoactive agent, has been chosen for this study which was performed in parallel double-blind conditions vs placebo. 32 patient. (24 males and 8 females) with either prosthetic heart valves, aortoiliac grafts or occlusive arterial disease were investigated [mean PRT t/2 value before treatment for the S group (n=16), 2.8±0.1 days]. They were given S at a dose of 600 mg daily during 3 to 4 weeks. The results obtained indicate that S treatment significantly increases shortened PRT t/2 values (mean PRT t/2 value after S treatment : 3.8±0.2 ; p<.001). Placebo treatment had no effect in a similar group of patients (n=16 ; mean PRT t/2 value before treatment : 3.0±0.1 days ; after treatment : 3.2±0.2 days). (1) R. Roncucci et al., Thromb.Res., accepted for publication.

Platelet Survival and Function in Animals with Prosthetic Mitral Valve: The Effect of Nafazatrom

1984 ◽  
Vol 52 (02) ◽  
pp. 099-101
Author(s):  
H Al-Mondhiry ◽  
W S Pierce ◽  
W Richenbacher
Keyword(s):  
Platelet Aggregation ◽  
Heart Valves ◽  
Ex Vivo ◽  
Oral Drug ◽  
Prosthetic Heart Valves ◽  
Antithrombotic Agent ◽  
Mitral Valves ◽  
Platelet Survival ◽  
Survival Studies ◽  
And Function

SummaryThromboembolism remains a serious problem in patients with prosthetic heart valves. Previous studies documented a number of platelet abnormalities in such patients and correlated the occurrence of thromboembolic complications with short platelet survival. We have studied platelet survival and platelet aggregation in eight goats fitted with prosthetic mitral valves and repeated the studies following treatment with nafazatrom, a potent antithrombotic agent. Eleven survival studies in eight animals showed a platelet survival not significantly different from control (6.52 ± 0.72 vs. 6.94 ± 0.81 days). Following seven to ten days of oral drug administration, platelet survival in the test animals was 7.34 ± 0.96 days, significantly longer than pretreatment results (p <0.01). Animals with the shortest pretreatment platelet survival achieved substantial prolongation of platelet life span following drug treatment. The drug caused no change in ex vivo platelet aggregation.

Stereoscopic PIV Measurements of Flow in a Model Left Ventricle with Prosthetic Valves

2004 ◽  
Author(s):  
Donal J. Taylor ◽  
Nathan J. Quinlan ◽  
John A. Eaton
Keyword(s):  
Left Ventricle ◽  
Heart Valves ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Stereoscopic Particle Image Velocimetry ◽  
Laboratory Model ◽  
Prosthetic Heart Valves ◽  
Mitral Valves ◽  
Prosthetic Valves ◽  
Component Velocity

Fluid dynamic phenomena are fundamentally important in the function of the heart, and consequently in the design of prosthetic heart valves. Experimental study is complicated by the strongly unsteady and three-dimensional character of flow in the chambers and valves of the heart, and the difficulty of access for instrumentation, even in a laboratory model. This paper describes the novel application of Stereoscopic Particle Image Velocimetry (SPIV) to measure the three-component velocity vector field in a model of the left ventricle with mechanical prosthetic valves. The results illustrate key functional differences between the two prosthetic mitral valves tested. These experiments demonstrate the powerful capability of SPIV as a tool for investigation of the complex flows which occur in biology and medicine.

scholarly journals Prosthetic Heart Valves and Pregnancy: Challenges and Solutions

2018 ◽  
Vol 03 (02/03) ◽  
pp. 115-125
Author(s):  
Akshyaya Pradhan ◽  
Vikas Gupta ◽  
Pravesh Vishwakarma
Keyword(s):  
Heart Valves ◽  
Heart Diseases ◽  
Care Center ◽  
Tertiary Care ◽  
Normal Pregnancy ◽  
High Rate ◽  
Prosthetic Heart Valves ◽  
Prosthetic Valves ◽  
Dose Warfarin ◽  
Valvular Heart Diseases

AbstractWith improved outcomes of valvular heart diseases and prosthetic valves, many women now survive into child-bearing age and pregnancy. However, the presence of prosthetic valves in pregnancy has an adverse impact on both maternal and fetal outcomes. The bioprosthetic or tissue valves are less thrombogenic. They do not need any anticoagulation and lead to normal pregnancy with normal baseline valve function. However, they have high rate of structural degeneration, especially in the young with an attendant need of reoperation leading to morbidity. Mechanical valves have excellent hemodynamics during pregnancy but are inherently thrombogenic leading to thromboembolic complications, necessitating uninterrupted anticoagulation. Anticoagulation itself leads to a host of maternal and fetal bleeding complication as well as adverse fetal anomalies. The use of low-dose warfarin throughout pregnancy has the best maternal safety profile. Added to this regimen, targeted replacement with parenteral heparin during the first (6–12 weeks) and late third trimesters (beyond 36 weeks) leads to virtual elimination of embryopathy as well as appreciable reductions of maternal mortality. Proper preconception counseling and antenatal care coupled with planned labor or delivery is essential to ensure best outcomes. These patients are best managed in a tertiary care center with proper expertise in managing adverse cardiovascular, obstetric, and neonatal outcomes.

Platelet Inhibition in the Management of Thrombosis

1974 ◽  
Vol 32 (01) ◽  
pp. 021-034 ◽  
Author(s):  
Paul Didisheim ◽  
Francis J. Kazmier ◽  
Valentin Fuster
Keyword(s):  
Deep Vein Thrombosis ◽  
Arterial Thrombosis ◽  
Heart Valves ◽  
Antiplatelet Agents ◽  
Platelet Inhibition ◽  
Prosthetic Heart Valves ◽  
Vein Thrombosis ◽  
Cerebral Ischemic ◽  
Deep Vein

SummaryThe role of platelets in the initation of arterial thrombosis is clear. In venous thrombosis as well, platelets may in some circumstances play a significant role.For these reasons, and because of the complications and limitations of anticoagulant therapy, antithrombotic trials have been launched with several agents which inhibit platelet function.Regarding postoperative deep vein thrombosis, neither aspirin nor dipyridamole alone appears effective, although the combination offers promise. Results with the dextrans are conflicting. In recurrent idiopathic deep vein thrombosis, sulfinpyrazone may be beneficial.On the arterial side, transient cerebral ischemic attacks may be favorably affected by either aspirin or sulfinpyrazone. Prevention of thromboembolism associated with prosthetic heart valves appears possible with combination warfarin-dipyridamole therapy, and the beneficial effect of sulfinpyrazone on shortened platelet survival in this group suggests that this agent may also be effective. Sulfinpyrazone may also be beneficial in preventing thrombosis in arteriovenous canulas.The issue which has attracted the greatest attention and about which no clear answer exists at present is whether antiplatelet agents can modify the course of acute myocardial infarction. Several trials with aspirin are currently underway, and it would be premature to recommend its use in this condition until the results of these trials are available, probably in 1975.

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