Fluid Mechanics of Thrombus Formation
Uri Dinnar in Cardiovascular Fluid Dynamics, 2019
This chapter focuses on the fluid mechanic aspects of thrombus formation. The process of formation of thrombus, known as thrombosis, is an essential mechanism in the process of hemostasis. The formation of venous thrombi is closer to that of blood coagulation and consists mainly of trapped red blood cells and fibrin. The formation period of thrombi is only a few seconds which makes it very hard to experimentally study the stages of thrombosis; it is however, well-accepted that in the early stages of the phenomenon only the platelets take part by adhering to acutely injured vessels. The mechanisms related to formation of thrombi are a complex interaction between flowing blood constituents, the blood vessel walls, and the flow conditions which is sometimes defined incorrectly as deviation of blood flow from a laminar pattern. The more complex phenomenon is the coagulation process in flowing blood which is closely related to a convective diffusion mechanism.
Natural history of acute DVT
Anthony J. Comerota in Practical Phlebology, 2014
The goal of treating deep vein thrombosis (DVT) is to prevent pulmonary embolism (PE) and death from PE, reduce the risk of recurrent DVT, and avoid postthrombotic morbidity. To manage DVT optimally, an understanding of its natural history is important. It is helpful to conceptualize venous thrombosis as an imbalance of the patient’s coagulation system with the fibrinolytic system at the time of the acute event and over the long term. Anticoagulation is designed to shift this imbalance toward the patient’s endogenous fibrinolytic system to reduce endovenous coagulation. If the patient’s fibrinolytic system is capable of resolving the majority of the acute clot, postthrombotic morbidity will be reduced and potentially avoided. However, if the effectiveness of the fibrinolytic system is minimal or if thrombus extension or rethrombosis occurs, the likelihood of additional venous thromboembolic complications and postthrombotic morbidity is high.
Strategy of thrombus removal
Anthony J. Comerota in Practical Phlebology, 2014
A large body of evidence indicates that early elimination of thrombus prevents or reduces postthrombotic morbidity. This is especially true in patients with iliofemoral deep vein thrombosis (DVT). Considering that the common femoral vein, external iliac vein, and common iliac vein are a single channel responsible for the entire venous drainage from the lower extremity, occlusion of the iliofemoral system leads to severe venous hypertension at the time of the acute event1 and persistently high venous pressures chronically.2 Early removal of the thrombus from the iliofemoral system restores venous (compartment) pressures to normal1; therefore, it would be anticipated that eliminating acute outflow obstruction would substantially improve long-term results. Every randomized trial to date and essentially all comparative studies assessing the value of thrombus removal in patients with iliofemoral DVT have demonstrated benefit.
Effect of Thrombus Aspiration on Angiography and Outcome in Patients Undergoing Primary Coronary Angioplasty
Published in Baylor University Medical Center Proceedings, 2017
Praveen Chacko, Kesavapillai Jayaprakash, Kamarudheenkunju Jameelabeevi Raihanathul Misiriya, Suresh Madhavan, Vasantha Sudha Kumary, Narayanapillai Jayaprasad, Vaikathusseril Lembodaran Jayaprakash, Raju George
Thrombus exerts a major impact on the performance and outcome of primary and rescue interventions in acute ST-elevation myocardial infarction. Although the optimal treatment of thrombotic lesions is still controversial, thrombus aspiration provides an effective method to achieve successful reperfusion during primary angioplasty. We compared clinical and angiographic outcomes in 286 patients with acute ST-elevation myocardial infarction undergoing primary percutaneous transluminal coronary angioplasty (PTCA) and thrombus aspiration with those who underwent conventional PTCA without thrombus aspiration. Thrombus aspiration during primary percutaneous coronary intervention in patients with high thrombus burden resulted in better Thrombolysis in Myocardial Infarction (TIMI) 3 flow in the infarct-related artery and helped achieve faster ST-segment resolution on the electrocardiogram compared with conventional angioplasty without thrombus aspiration.
A review of thrombectomy devices
Published in Expert Review of Medical Devices, 2012
Acute coronary syndrome is associated with a high incidence of thrombus. The presence of coronary thrombus is often not appreciated on coronary angiography; however, simultaneous use of angioscopy or intravascular ultrasound increases the detection of thrombus. Forceful coronary injection, passage of intracoronary devices, balloon angioplasty and stenting in the presence of thrombus contribute to distal embolization by disrupting the thrombus. Clinically, intracoronary thrombus is associated with higher rates of death, myocardial infarction and target vessel revascularization. Removal of thrombus results in the improvement of markers of perfusion, which includes resolution of ST segment elevation, higher myocardial blush grade, and an increase in final thrombolysis in myocardial infarction flow as well as lower mortality. In this article, the authors discuss different mechanical thrombectomy devices and the literature available for their use in acute coronary syndrome.
Myocardial infarction with non-obstructive thrombus validated by optical coherence tomography
Published in Scandinavian Cardiovascular Journal, 2017
Kevin Kris Warnakula Olesen, Trine Ørhøj Barkholt, Michael Maeng
Purpose. Coronary angiography provides no details on underlying pathology in acute coronary syndromes (ACS). Optical coherence tomography (OCT) can visualize coronary atherosclerosis, thrombus formation, and plaque rupture in patients with myocardial infarction (MI) where coronary angiography is unclear. Materials and methods. We present a case series containing six young patients with ACS, four of them due to non-obstructive thrombus, in whom the operators refrained from stent implantation despite an identifiable culprit lesion with OCT-validated thrombus formation. Results. The median age was 31.5 years. In four of these six patients, no invasive intervention was performed while the remaining two patients underwent thrombus aspiration and balloon angioplasty without stent implantation. Four patients were examined at the primary evaluation and all patients were examined by OCT between 3–5 days after initial examination. This short-term follow-up with OCT showed non-obstructive thrombus formation in all patients with varying degrees of thrombus resolution. No adverse cardiac events were reported after a median follow up of 5.5 months. Conclusions. OCT can visualize thrombus formation in young ACS patients with non-obstructive thrombus or following thrombus reduction by aspiration and balloon dilatation. These patients seems safely treated with a conservative medical approach rather than with stent implantation.