Prevention of Pulmonary Artery Embolism in Thrombosis of the Inferior Vena Cava System in Geriatric Patients

The dissertation addresses the problem of prevention of pulmonary artery embolism in thrombosis of the inferior vena cava system in geriatric patients. The work reviews current concepts of the etiopathogenesis, diagnosis, and treatment of thrombotic lesions in this location, and develops an algorithm for the prevention of pulmonary artery embolism in elderly and geriatric patients. The author examines clinical, radiological, and ultrasonic diagnostic methods for phlebothrombosis, analyzes the effectiveness of medication prophylaxis and surgical interventions, and formulates recommendations for conservative treatment and monitoring of thrombosis in the inferior vena cava basin. The results were implemented in clinical practice at hospitals and municipal clinical hospitals in Moscow and are used in educational activities at the Department of Surgical Diseases and Clinical Angiology of Moscow State Medical and Dental University.

Relevance of the problem

Pulmonary artery embolism (PAE) resulting from thrombosis of the inferior vena cava (IVC) system is one of the most severe and dramatically progressing complications with a high risk of fatal outcome [3, 7, 37, 42, 72-78, 94, 102, 105, 109, 134, 158, 172, 177, 200].

During life, the diagnosis of PAE is established in approximately 70% of observations. Mortality among patients without pathogenetic therapy, according to various authors, is 40% or more, reaching 70% in massive embolism, and ranging from 2% to 8% with timely initiated therapy [8, 51, 78, 93, 95, 139, 153, 158, 156].

According to the Framingham study, PAE accounts for 15.6% of all in-hospital mortality, with 18% attributable to surgical patients and 82% to patients with medical pathology [48, 64, 172].

In Russia, approximately 600,000 cases of PAE are registered annually, and one-third of patients with this diagnosis die. According to autopsy reports, among deceased patients who underwent surgery, 20% had PAE as the cause of death [78-81, 90]. In Western countries, the incidence of DVT and PAE is 1.0 and 0.5 per 1,000 population per year [158]. The annual incidence of deep vein thrombosis (DVT) in the United States is approximately 84 per 100,000 population [104, 158, 172].

Risk factors for the development of embolism in geriatric patients include all conditions predisposing to venous thrombosis: advanced age, prolonged bed rest; postoperative period; heart failure; varicose disease; obesity; malignant tumors; increased blood coagulability (antithrombin III deficiency, protein C and protein S deficiency, erythremia, dysfibrinogenemia); thrombocytosis after splenectomy; thromboembolic diseases in anamnesis [1, 7, 13, 43, 51, 56, 90, 101, 105, 142, 156, 176, 198].

In 90% of cases, the cause of PAE in surgical patients is thrombosis of the inferior vena cava, iliac veins, femoral veins, and calf veins [7, 36-38, 42, 109, 175, 177, 188, 200]. Approximately 75% of DVT cases are directly associated with various surgical interventions. Venous thrombosis with localization in the superior vena cava (SVC) system is complicated by PAE in 1-5% of cases [42, 78-79, 102]. Up to 10% of PAE cases are caused by thrombi of the right heart chambers [170].

At present, there is no consensus on the need for comprehensive measures for PAE prevention in elderly and geriatric patients with thrombosis of the IVC system, no defined group of patients at increased risk of developing phlebothrombosis, and the timing and doses of specific prophylaxis have not been finally established [198]. The algorithm of diagnostic and therapeutic measures for already occurring phlebothrombosis has not been developed. There are various opinions on dosing, timing, and methods of monitoring the effectiveness of medical therapy for thrombosis of the IVC system and surgical prophylaxis of PAE in elderly and geriatric patients [65, 70, 90, 108, 132].

The use of prophylactic anticoagulant therapy with heparin in medical institutions of surgical profile, especially in geriatric patients, reduces the risk of thrombosis of the IVC system and PAE, but due to the development of increased bleeding, especially after major operations, and the presence of concomitant pathology of other organs and systems, it poses a significant risk for this category of patients. As a result, there is no unified approach to the technique of prophylactic anticoagulant therapy with heparin, and it has not found widespread use in surgery. In this regard, great hopes are placed on the use of low-molecular-weight heparins (LMWH), due to their high bioavailability (90%) and low percentage of complications, which makes their use preferable in geriatric patients. In inflammatory and oncological processes, LMWH bind significantly less to acute-phase proteins, which does not require an increase in drug dosage. The frequency of LMWH administration and patient tolerability; low local reactions at injection sites are indisputable advantages compared to heparin.

Special significance is today attached to a complex of measures, including invasive ones, for the prevention of PAE. Widespread adoption has been achieved in foreign and some domestic clinics for the implantation of various modifications of vena cava filters in floating embologenic thromboses of the inferior vena cava and its tributaries. However, analysis of long-term results of vena cava filter implantation demonstrates that in certain cases, despite continuous intake of anticoagulants and antiplatelet agents, thrombosis of the filter itself occurs with development of IVC syndrome, leading to a persistent loss of working capacity.

Specific and nonspecific prophylaxis, early diagnosis, and adequate treatment of thrombosis of the IVC system in elderly and geriatric patients are the foundation for reducing the incidence of PAE and mortality.

Goal of the study

To develop an adequate algorithm for the prevention of pulmonary artery embolism in venous thrombosis in elderly and geriatric patients.

Tasks of the study

1. To study the frequency of phlebothrombosis and embolism in elderly and geriatric patients.

2. To evaluate the informativeness of various diagnostic methods for thrombosis of the IVC system.

3. To evaluate the effectiveness of various medication prophylaxis regimens as the primary treatment modality and in combination with surgical interventions.

4. To clarify indications and determine optimal variants of surgical interventions and their timing.

5. To study the short-term and long-term results of comprehensive treatment of lower extremity venous thrombosis.

Scientific novelty

In this work, the symptomatology of thrombosis in the IVC basin in elderly and geriatric patients has been thoroughly studied and systematized. The possibilities of various diagnostic methods for phlebothrombosis have been studied, including an analysis of ultrasonic diagnostics, CT, and MRI capabilities. It has been established that dynamic ultrasonic angioscintigraphy allows effective monitoring of the thrombotic process and timely determination of indications for conservative therapy and surgical interventions for PAE prevention. In conjunction with radiocontrast ilio-cavography, ultrasonic angioscintigraphy (UAS) makes it possible to identify an embolus-prone thrombus and establish indications for surgical PAE prophylaxis (ligation of the major vein, vena cava filter placement, etc.).

The possibilities of ultrasonic phlebography in monitoring the effectiveness of phlebothrombosis treatment are substantiated by the results of dynamic and clinical observation. An approach to conservative treatment of phlebothrombosis and surgical PAE prevention in elderly and geriatric patients has been modified.

Practical significance

Based on the conducted research, an algorithm for the diagnosis of thrombosis of the IVC system has been proposed. Indications for various surgical treatment options for phlebothrombosis have been clarified. Recommendations for conservative treatment and monitoring of thrombosis in the IVC basin and PAE prophylaxis have been developed.

Implementation in practice

The results of the conducted work, conclusions, and practical recommendations have been implemented in clinical practice in the treatment of patients at the Veterans Hospital No. 1 and City Clinical Hospitals No. 50, No. 81 of the Moscow Department of Healthcare.

The main provisions of the dissertation are used in lectures and practical exercises at the Department of Surgical Diseases and Clinical Angiology of the State Educational Institution of Higher Professional Education Moscow State Medical and Dental University.

Presentation of the work

The results of the dissertation work have been presented at the All-Russian Conference of Surgeons (Moscow, 2003), the V Annual Conference "Phlebology" (Moscow, 2004), the Mobile Plenum on Emergency Surgery (Yaroslavl, 2004), the Proceedings of the III All-Russian Conference of General Surgeons (Rostov-on-Don, 2005), the International Conference of Surgeons "Minimally Invasive Technologies in Surgery" (Makhachkala, 2005), and the 7th All-Russian Conference with International Participation (Moscow, 2006).

Structure and volume of the dissertation

The dissertation consists of an introduction, a literature review, four chapters of original observations, a conclusion, findings, practical recommendations, and a list of references. The work is presented in 121 pages of typescript, contains 14 tables and 30 figures. The reference list contains 220 sources (94 domestic and 126 foreign).