Annals of Vascular Diseases Vol. 10(2017) No. 2

The number of patients requiring hemodialysis is continuously increasing around the world. Hemodialysis affects patient quality of life and it is also associated with a higher risk for cardiovascular events. In addition to traditional risk factors for cardiovascular events such as hypertension, hyperlipidemia, and diabetes, hemodialysis is associated with hyperphosphatemia, chronic inflammation, vascular calcification, and anemia which accelerate atherosclerosis, vascular stiffness, and cardiac ischemia. Treatment strategy for coronary revascularization in this progressive disease remains controversial. However, a systematic treatment including medical therapy and complete revascularization through a less invasive strategy should be considered in addressing this problem. This review discusses the epidemiology, vascular pathology and current treatment options in patients with end-stage renal disease requiring coronary revascularization.

The prevalence of peripheral artery disease is substantially higher in patients on chronic hemodialysis than in the general population. The presence of calcified lesions characteristic of hemodialysis patients has an adverse influence on the initial success and long-term outcomes of both surgical bypass and endovascular therapy. Although the selection of revascularization strategy depends on whether an autologous vein is available and if the patient has a life expectancy of at least two years, it is difficult to predict the life expectancy in a real-world clinical situation. Endovascular therapy may be appropriate for many hemodialysis patients with poor general condition because of the high risk of perioperative complications and the poor long-term prognosis. Deciding which treatment option is more appropriate should be done on a case-by-case basis, especially in hemodialysis patients with critical limb ischemia.

The first-line treatment of venous thromboembolisms (VTE) is anticoagulant therapy, and unfractionated heparin and warfarin are used in Japan. However, as both drugs require dosage adjustments that are difficult, VTE recurrences occur relatively frequently, and hemorrhagic complications are extremely common. The parenteral factor Xa inhibitor fondaparinux and the direct oral anticoagulants (DOACs) edoxaban, rivaroxaban, and apixaban have recently become available as treatments for VTE in Japan. These novel anticoagulants have more stable effects than traditional therapies and are thus considered safer and more effective than the traditional agents. Especially, DOACs offer improved long-term prevention of recurrence in patients with unprovoked VTE. The initiation of DOAC monotherapy soon after VTE onset leads to shorter hospital stays than required with the older therapies and allows for outpatient treatment. DOACs have additional benefits, such as safer anticoagulant therapy for cancer patients. These novel anticoagulants are extremely promising, but there is a current lack of evidence in areas such as dosing regimens for highly vulnerable patients and dosing for long-term use, and alternative regimens for each DOAC.

Here the pathophysiology of venous thromboembolism is reviewed with respect to the anatomical features of the deep veins of lower limbs. A thrombus is less likely to form in the thigh veins compared with that in the calf veins; however, clinical symptoms are more likely to appear in the thigh veins owing to vascular occlusion. When a patient is bedridden, thrombosis is more likely to occur in the intramuscular vein, which mainly depends on muscular pumping and the venous valve, rather than in the three crural branches, which mainly depends on the pulsation of the accompanying artery. Thrombi are prone to be generated in the soleal vein compared with those in the gastrocnemius vein because of the vein and muscle structures. A soleal vein thrombosis grows toward the proximal veins along the drainage veins. To prevent a sudden pulmonary thromboembolism-related death in bedridden patients, preventing soleal vein thrombus formation and observing the thrombus proximal propagation via the drainage veins are clinically important. When deep vein thrombosis occurs, avoiding embolization and sequela caused by the thrombus organization is necessary.

Acute pulmonary thromboembolism is a catastrophic event, especially for hospitalized patients. The prognosis of pulmonary thromboembolism depends on the degree of pulmonary arterial occlusion. The mortality of massive pulmonary embolism is reportedly as high as 25% without cardiopulmonary arrest and 65% with cardiopulmonary arrest. In patients with unstable hemodynamics due to pulmonary thromboembolism, surgical pulmonary embolectomy is indicated for patients with a contraindication to thrombolysis, failed catheter therapy, or failed thrombolysis. Thrombolytic therapy adds an additional burden on patients who are at risk of potential hemorrhagic complications. It is also indicated if patients are already on a veno-arterial extra-corporate membrane oxygenator for circulatory collapse or cardiopulmonary arrest. The outcome for patients who require cardiopulmonary resuscitation for longer than 30 minutes is poor. Therefore, early triage for massive and sub-massive pulmonary embolism is crucial. A team approach including a cardiovascular surgeon may be effective to save critically ill patients. Prompt removal of emboli reduces the right ventricular load with quick recovery of cardiopulmonary function in the early postoperative period. A recent series reported excellent results, with in-hospital mortality of less than 10%. Surgical pulmonary embolectomy is an effective, safe, and easy procedure to save critical patients due to pulmonary thromboembolism.

Objective: To evaluate the relationship between varicose veins and heart failure, both of which cause edema of lower extremities.

Materials and Methods: We enrolled 150 patients who underwent intervention for varicose veins of lower extremities between December 2012 and October 2015, and perioperative data were retrospectively investigated.

Results: Of the 150 patients, 104 (69.3%) were females. The mean age was 66.8±10.6 years (27–85 years). Eighty (53.3%) patients had varicose veins in both legs. In all patients, the postoperative (brain natriuretic peptide (BNP) value was significantly lower than the preoperative BNP value (pre : post=39.3 : 30.5 pg/dl, P<0.0001). In patients with higher BNP values (>100 pg/dl), the postoperative BNP values were significantly lower than the preoperative BNP values (pre : post=192.7 : 166.1 pg/dl, P<0.0001). Body weights of the patients decreased differently between pre- and post-operation (pre : post=61.3 : 59.4 kg, P=0.0008).

Conclusion: Intervention for varicose veins of lower extremities might be considered clinically useful for the improvement of cardiac function.

Objective: We investigated the characteristics and surgical outcomes of abdominal aortic aneurysm (AAA), which typically occurs in elderly persons, in Japanese patients aged 50 years or younger.

Materials and Methods: Clinical records of 999 patients who underwent open or endovascular repair for AAA at our hospital between 2007 and 2015 were reviewed to identify the clinical characteristics and surgical outcomes of young patients with AAA. The cohort included 14 patients aged 50 years or younger (mean, 40.4 years; young group) and 985 patients aged older than 50 years (mean, 72.8 years; old group).

Results: Marfan syndrome, prior aortic dissection, and a history of aortic surgery were more prevalent in the young group, and 50% of the patients in the young group had dissecting aneurysms. All patients in the young group underwent open repair. Overall in-hospital mortality rates were 7.1% (1/14) and 1.9% (19/985) in the young and old groups, respectively (P=0.67). Seven-year survival and aortic event-free survival rates in the young group were 82.5%±11.5%, and 71.2±14.5%, respectively.

Conclusion: AAA in patients aged 50 years or younger tended to be associated with Marfan syndrome, a history of aortic surgery, and prior aortic dissection. Early outcomes of AAA among young patients are acceptable, but close postoperative monitoring is important.

Objective: To evaluate the influence of pre-procedural characteristics on immediate and late results as well as the safety of catheter-directed thrombolysis (CDT) in acute ischemia of the lower extremity.

Materials and Methods: A retrospective study comprising 249 patients treated by CDT from January 2006 to December 2012. Outcomes were primary patency, haemorrhagic complications, amputation and mortality.

Results: Primary patency for CDT alone was 68%, for CDT plus endovascular treatment 87% and for successful CDT with supplementary surgery 62% giving an overall primary patency of 76%. Two (0.8%) patients suffered from cerebral haemorrhage during CDT. We found a significant correlation between 30 day amputation rate and no visual distal run-off at CDT start (OR 2.31; CI95% 1.09–4.91; p-value=0.02) and onset of symptoms to CDT start of 8–14 days (OR 4.09; CI95% 1.42–11.81; p-value=0.01). Lack of visualized distal run-off was also associated with a significant risk of 30 day mortality (OR 5.84; CI95% 1.26–27.00; p-value=0.02).

Conclusion: Our results show that CDT is a feasible and safe treatment option especially when combined with angioplasty +/− stent. However, no distal run-off at primary angiography is associated with higher rates of amputation during follow-up and 30 day mortality.

Objective: To evaluate in vivo patency rates of silk fibroin (SF) vascular grafts and resulting histological reactions in a canine model.

Methods: To generate 3.5-mm inner diameter vessels, a combination of plaited silk fibers were wound with cocoon filaments and subsequently coated with an SF solution. The resulting SF grafts (n=35) were implanted into the carotid arteries of male beagles (age, 1–2 years; body weight: 9.0–10.5 kg). Expanded polytetrafluoroethylene (4-mm inner diameter, ePTFE) grafts (n=5) were used as controls. Graft patency was monitored via ultrasonography with histological changes analyzed via microscopic examination.

Results: Compared with animals that received the ePTFE grafts, animals that received SF grafts exhibited the same thickness of luminal layers and fibrin accumulation and collagen fiber replacement with endothelialization at 3 months post-implantation via histological examination. The patency rates of the SF and the ePTFE grafts at 6 months post-implantation were 7.8% and 0%, respectively.

Conclusion: This canine model study demonstrated that SF grafts induce unique histological reactions but fail to achieve long-term patency.

The causative organism is not identified in some cases of infected aneurysms, a life-threatening condition. A 68-year-old man presented with chest/back pain and a 1-year history of intermittent fever and fatigue. Computed tomography revealed a thoracic aortic aneurysm. After several negative blood cultures, he was eventually diagnosed with an infected aneurysm caused by Helicobacter cinaedi via gene analysis of an aortic tissue specimen. As H. cinaedi is a low-virulence bacterium, infection with this pathogen should be suspected in cases of aortic aneurysms with unidentified causative organism and a long history of subjective symptoms. Detailed examinations, including polymerase chain reaction, should be conducted in such cases.

Mycotic aneurysm of the aorta is a rare, but life-threatening pathology. In recent years, endovascular stent graft placement has been introduced as an effective alternative for treating infected aortic aneurysms. A 64-year-old woman with a history of paraplegia due to spinal cord injury was referred to our institute with fever and blood-tinged sputum. Computed tomography (CT) scan showed an 11-cm pseudoaneurysm arising from the proximal descending aorta, which was normal 1 month ago at the previous CT scan. The patient underwent thoracic endovascular aortic repair for the pseudoaneurysm, deployed with a transiliac access approach, and received antibacterial medical therapy. On postoperative day 11, she developed signs of infection, caused by an aortoesophageal fistula. The infection was treated conservatively with parenteral nutrition and antibiotic administration. The patient had an uneventful recovery and was discharged on postoperative day 113. At 2-year follow-up, she had a normal physical examination and CT angiography showed a marked reduction of the pseudoaneurysm sac. We report a successful endovascular stent grafting and subsequent medical treatment in a patient with a mycotic thoracic aortic pseudoaneurysm followed by a postoperative aortoesophageal fistula.

We report a rare case in which a patient required three surgeries with competing priorities. In a 68-year-old man diagnosed with an abdominal aortic aneurysm (AAA), computed tomography (CT) revealed an infrarenal AAA, unusual thickening of the sigmoid colon that suggested cancer, and a filling defect in the left atrium. We considered the disease stage, which affects prognosis, and the risk of complications that could interfere with the treatment of the other pathologies and developed a three-stage surgical strategy: (i) endovascular aortic repair, (ii) sigmoid colectomy, and (iii) resection of the left atrial mass. The patient’s postsurgical recovery was uneventful.

A 68-year-old man with Marfan syndrome developed de-novo leakage after endovascular aneurysm repair of a Dacron graft. Findings at subsequent reoperation suggested that the rebound force on the endograft generated by marked longitudinal deformation in the Dacron graft may have placed stress on the suture line, leading to partial dehiscence. The Dacron graft seemed to provide a stable proximal landing zone. However, the strong tendency of some endograft devices to return to their original shape may apply stress that affected weakened regions of the native aorta.

A 72-year-old woman with a history of malignant lymphoma was referred to our hospital for the treatment of a bronchial artery aneurysm. Computed tomography (CT) scan showed a round, 30 mm-diameter fusiform aneurysm with two tortuous inflow arteries. We deployed thoracic stent grafting to cover the orifice of the two inflow arteries without transcatheter bronchial arterial embolization. Postoperative CT scan revealed complete thrombosis of the aneurysm. Although further follow-up is mandatory, this may be considered a viable treatment option in cases wherein the bronchial artery aneurysm is anatomically difficult to treat.

An 82-year-old man suffering from lower back pain and dyspnea presented to our institute in a state of shock. Computed tomography showed subtotal occlusion of the descending aorta with massive atherosclerotic calcification. As the proximal portion of the superior mesenteric artery was obstructed, emergency bypass from the right axillary artery to the bilateral external iliac arteries was performed, but the patient died 2 days later. Autopsy revealed that reddish-brown and verrucous masses obstructed the descending aorta, and high-grade thickening of the intima and extensive deposits of calcium in the lumina and medial layer were detected in the descending aorta histologically.

The surgical outcomes in patients with mycotic aortic aneurysm are still poor. In situ reconstruction and extra-anatomical bypass are the 2 main surgical options used in these patients, both of which have postoperative complications: recurrence of infection and aortic stump blowout, respectively. We performed in situ reconstruction in 25 consecutive patients with mycotic abdominal aortic aneurysms together with extended debridement using an irrigation device, omental flap coverage, rifampicin-soaked prosthetic graft, and sufficient antibiotics administration. There were 3 in-hospital mortalities; however, no infection- or procedure-related adverse events were observed in other cases during the mid-term follow-up period.