Image-guided, catheter-directed, intra-thrombus drug delivery has been developed for improving the safety and efficacy of thrombolytic therapy for thromboembolic disease. CDT has several advantages for DVT patients and can be used:

Catheter-directed thrombolysis (CDT) means delivery of a thrombolytic drug (rtPa, Urokinase) directly into the thrombus using a catheter or catheter-like device that is embedded within the thrombus by using Doppler ultrasound and fluoroscopy guidance. Usually a standard multisidehole catheter might be used but recently a multisidehole catheter that simultaneously applies ultrasound energy (EkoSoniccatheter; EKOS) to improve drug delivery into the thrombus has also been developed and this device is expected to increase safety and efficacy [4, 5, 10] (Fig. 1).

Currently, the most commonly used fibrinolytic drug for DVT is the recombinant tissue plasminogen activator (rtPA). The drug is infused continuously and directly into the thrombus at a low dose (0.5–1.0 mg/h) with systemic intravenous infusion of unfractionated heparin at subtherapeutic levels. Mostly the patient is closely monitored in an intensive care unit. Infusion might be stopped in case of active bleeding or severely abnormal coagulation parameters. Patients are evaluated by venography 1–2 times a day until the patency is achieved. Venous balloon angioplasty with thrombolytic infusion may also be used after partial thrombolysis [4, 5]. Left iliac anatomical venous stenosis (May-Thurner Syndrome) is usually treated by venous stent implantation and other venous stenoses might also be treated by balloon angioplasty and/or stent placement [4, 13]. Venography is performed to confirm the patency of the venous system. Before the patient is discharged anticoagulant therapy is arranged and compression stockings are prescribed. CDT has been evaluated in many case series and prospective multicenter trials. Major bleeding was observed in 5–12 % of patients in some older studies. However, more recent series with RCT reported much lower major bleeding rates [4, 5, 11, 12]. Fatal PE after CDT has also been reported very rarely [4, 14]. Although CDT is effective, currently the technique is not used widely because of long infusion times with intensive monitoring that are associated with longer hospital stays, and the risk of systemic bleeding still exists.

Pharmacomechanical catheter-directed thrombolysis (PCDT) includes intrathrombus thrombolytic agent infusion with mechanical thrombectomy devices to improve drug penetration into thrombus and macerate thrombus for aspiration or percutaneous thrombectomy [5, 11]. These devices enable faster penetration of thrombolytic agent within the thrombus, accelerating successful thrombolysis and improving safety by reducing drug dose and exposure time. Successful use of PCDT has been described in a number of published DVT studies [15–17]. Recently, new PCDT devices have been introduced that can enable endovascular DVT therapy to be completed in a single procedure session without the need for further drug infusions or intensive care monitoring. AngioJet Thrombectomy System (Boston Scientific) gives forceful pulse-spray bolus dose of the thrombolytic drug directly into the thrombus [18]. The drug is allowed to interact within the thrombus for a while and the device is used to aspirate the residual thrombus at the end. Isolated thrombolysis is another method performed by Trellis Peripheral Infusion System (Covidien) [5, 19]. With this device two catheter-mounted balloons are inflated to isolate a segment of vein and a bolus dose of a thrombolytic drug is injected directly into the thrombus. Activation of an oscillating wire for 10 min is then used to mechanically disperse the drug within the thrombus, and then the drug and liquefied debris are aspirated through a port on the device. Another similar device is Reya Thrombectomy catheter (Biolas Health) that is designed to use with the implantation of a temporary retrievable vena cava filter for protection before activation of an oscillating wire (Fig. 2). There are also many different endovascular venous thrombus aspiration systems such as Aspirex S Catheter (Straub Medical) and Angiovac Cannula and Circuit (AngioDynamics).

Although definitive multicenter RCTs comparing the most recent PCDT, CDT and combined methods have not been published yet, current practice shows strong clinical tendency for the use of PCDT with or without other endovascular methods and an individualized approach for each DVT patient [4, 5, 20].

Stand-alone percutaneous mechanical thrombectomy (PMT) refers to the percutaneous use of catheter-based mechanical devices that contribute to thrombus removal via fragmentation, maceration, and/or aspiration, without administration of a thrombolytic drug. These methods are not always suitable for every patient and in most of the cases they are reserved for the patients with serious risk of bleeding and/or other contraindications for the thrombolytic therapy. PMT has not received general acceptance because of the associated risk of PE and damage to venous valves caused by thrombectomy devices [10, 13].

Percutaneous aspiration thrombectomy (PAT) technique can be defined as using a syringe to aspirate thrombus from the vein via a catheter, device, or sheath. PAT has been routinely used to effectively eliminate thrombi located in hemodialysis fistulae with a patency rate of 86 % at 6 months after PAT [21]. PAT also has been accepted as a rapid, safe, and effective method of management of iliofemoral vein thrombosis and provides higher recanalization rates than alternative treatments [13]. However, few clinical studies have been performed. Previous studies reported a recanalization rate of 88.9 % with PAT for the lower extremity DVT. Mechanical thrombectomy devices are not required during PAT and, therefore, the risk of trauma to the vascular wall and valves is thought to be low. Thrombolytic agents are not given to PAT patients, and the bleeding complications associated with systemic therapy are therefore absent [13, 22]. However there is no standardized PAT aspiration method and the technique is not widely accepted. PAT is most commonly used as an adjunctive endovascular technique like balloon maceration to fragment thrombus, balloon angioplasty, stent implantation and vena cava filter placement (Fig. 3).

Interventional endovascular therapies for DVT have the potential to provide PE protection and prevention of PTS. There is increasing number of scientific evidence in support of endovascular treatments. However, patient centered individualized approach for endovascular DVT treatment is recommended to optimize the ideal clinical result.

An acute stroke patient first seen in a hospital with the capability of intravenous (IV) fibrinolysis must have a nonenhanced computerized tomography (NECT) of the head to rule out cerebral hemorrhage. Patients without significant improvement after IV fibrinolysis can be immediately transferred to higher-level stroke centers. Patients that are seen by the emergency medical services in the field will benefit more if they can be sent to the nearest stroke center with the capability of both intravenous and intraarterial therapy and dedicated neurovascular imaging capabilities. IV recombinant tissue plasminogen activator (alteplase, rtPA) was the first approved treatment for acute ischemic stroke within 3 h of stroke onset after the NINDS (National Institute of Neurological Disorder and Stroke) trial. There are several exclusion criteria for the IV fibrinolytic therapy (Table 2).

The American Stroke Association (ASA, 2013) published guidelines for the early management of patients with acute ischemic stroke [26] (Tables 3, 4 and 5).

Recommendations with the highest level of evidence and that are directly related with the endovascular management of acute stroke are included. Recommendations regarding the intensive care management of acute stroke patients are not within the scope of this article. According to these guidelines an algorithm for management of acute stroke patients can be formed (Table 6).

Recanalization rates after IV rtPA in internal carotid artery terminus and MCA M1 segment occlusions range between 10 and 50 % and less than 40 % of patients regain functional independence [27]. Endovascular therapy has the main advantage of extended therapy window, earlier and more efficient recanalization and less risk of hemorrhage due to lower doses of thrombolytics. Endovascular therapies include either application of local intraarterial thrombolytics in the occluded intracranial segment or mechanical removal of the clot with a thrombectomy device or another endovascular device like a balloon or stent. According to most recent guidelines safe therapy window for endovascular treatment is the first 6 hours after the stroke onset [26]. After the development of dedicated mechanical thrombectomy devices, including stent retrievers, the balloon angioplasty has been put aside. Major disadvantages of endovascular therapies include low availability due to requirement of high level of expertise of specialists and complex neurointerventional infrastructure, delay in therapy initiation and invasive nature of the endovascular methods. Potential complications of endovascular stroke treatment are reperfusion hemorrhage, distal emboli, intracranial dissections, hematomas and subarachnoid hemorrhage [28, 29].