Cover Story

Available Technologies for Endovascular Treatment

There are several endovascular technologies available for use in treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE). They work quite differently from one another and many are used off-label in the United States. Cardiology Today’s Intervention asked experts to explain the available different devices.

EkoSonic Endovascular System

One of the more commonly used endovascular devices for DVT intervention is the EkoSonic Endovascular System (EKOS Corp.). This system uses a thrombolytic drug through a catheter, and additionally includes a device which generates low-intensity, high-frequency ultrasonic waves to accelerate the process.

“You basically deliver these catheters into the lung and there is an ultrasound core wire that fits in the lumen of this catheter; the wire has little ultrasound transducers that when spaced apart, may deliver this high-frequency ultrasound,” Victor F. Tapson, MD, professor of medicine, pulmonary and critical care at Cedars-Sinai Medical Center, Los Angeles, said. “You put normal saline through a coolant port that’s connected to this lumen, and this helps to diffuse the heat energy that’s generated. Then, you have these infusion catheters, and you deliver the ultrasound while you deliver low-dose thrombotic therapy.”

Kenneth Rosenfield, MD, MHCDS, FACC, FSCAI, section head of vascular medicine and intervention at Massachusetts General Hospital, said he has frequently used the EkoSonic system with good results. “Most of the time when [choosing catheter-directed thrombolysis (CDT)], we’re using EKOS catheters,” he said. “We have been very satisfied, very impressed that this is an effective therapy. Usually it’s 1 mg per hour in each side, and within 4 to 6 hours, patients feel different. They describe a lifting of the pressure on their chest, they’re breathing easier and their heart rate slows down.”

The system has been evaluated in two clinical trials, SEATTLE II and ULTIMA. In the ULTIMA trial, which was a randomized controlled trial, therapy with the EkoSonic Endovascular System was found to be superior to heparin monotherapy in reversing right ventricular dilatation at 24 hours. The SEATTLE II trial, which was a prospective, single-arm, multicenter trial, found that therapy with the system reduced RV dilatation, pulmonary hypertension and anatomic thrombus burden, and lessened intracranial hemorrhage in patients with acute massive and submassive PE.

“This technique is the one we’re getting the most data on. It’s the one that’s FDA-approved for PE, and I will give EKOS credit for continuing to try to get data and help us advance this field,” Tapson said. “One of the problems with this field is that we don’t have enough randomized clinical trial data. The ULTIMA study was a randomized study; SEATTLE II was single-arm, but 150 patients. These are the best we have.”

Inari FlowTriever

Another system for the endovascular treatment of patients with acute PE is the FlowTriever Retrieval/Aspiration System (Inari Medical). This system uses a catheter-based mechanical thrombectomy device to percutaneously retrieve emboli from the peripheral vasculature.

Three discs “are expanded in the pulmonary artery. They engage the clot, and are then sucked back in with a lever-type device into a 20F sheath,” Rosenfield said. “The 20F sheath extracts, the clot comes back with the FlowTriever discs, and you remove the device. Nothing completely removes the thrombus. All you need to do is relieve the major obstruction, and the patients get better. The rest of the thrombus is dissolved by itself.”

Rosenfield and Tapson are co-principal investigators of the FLARE study, a prospective, multicenter, single-arm study assessing the FlowTriever in 150 patients with acute PE. The study will be conducted at up 20 clinical sites in the United States.

“We don’t have a lot of data yet,” Tapson said. “This device has been used in a number of cases around the country, but the exciting part now is again getting a study underway to look at FDA approval.”

The device is FDA-approved to treat emboli in the peripheral vasculature, but not to treat PE.

Penumbra Indigo System

The Indigo Mechanical Thrombectomy System (Penumbra Inc.) is a trackable thrombectomy system featuring a proprietary aspiration pump that provides suction through a catheter.

According to John Moriarty, MD, a specialist in vascular and interventional radiology at UCLA, this system originated in stroke therapy.

“The original devices were used for removing blood clots in the brain. The catheter was advanced into the blood clot and then attached to a vacuum suction, which directly sucked the clot out of the blood vessel and removed it,” he said. “The Indigo device uses the same basic idea, but uses larger catheters with different properties, such as different angles on them, to remove the blood clots from the venous system. It is good at removing clots from places that are difficult to reach because it is a very torque-able, very deliverable catheter.”

Keith M. Sterling, MD, from Inova Alexandria Hospital, Alexandria, Virginia, said the system has been particularly effective in patients who require catheter-based clot removal but have a contraindication to thrombolytic agents. “Striking results have been achieved in patients with massive and submassive PE with performing an ‘on the table’ treatment, with reversal of right heart dysfunction and stabilization of the patient’s hemodynamic status.”

The device is FDA-approved to treat emboli and thrombi in the peripheral arterial and venous systems, but it is not approved for use in the coronary vasculature.

AngioJet System

The AngioJet Thrombectomy System (Boston Scientific) is a device used in rheolytic thrombectomy, a technique that aspirates the thrombus locally. While the system has been used to treat PE, it is not FDA-approved for this indication, and the FDA has issued a black box warning for its use in patients with acute massive PE.

“It’s a device that sends pressurized saline to the catheter tip, and these saline jets travel backward to create a little pressure zone, causing a vacuum effect,” Tapson said. “The thrombus is drawn in through this inflow window, and the jets push the thrombus back down the catheter, so it’s evacuated.”

Rosenfield said he has personally been cautious in using the AngioJet System, but some physicians have reported positive outcomes associated with use of the technology.

“Patients have developed bradycardia and hypotension with this device. I’ve been a little bit cautious about using it, but I did see someone present a series of 50-odd cases with very good results,” he said.

The device is approved for treatment of DVT and other peripheral conditions.

Vortex AngioVac device

Another novel technology that is currently used to treat patients with acute DVT or PE is the Vortex AngioVac device (AngioDynamics). This device utilizes a cannula and an extracorporeal unit with a filter for pump-supported removal of intravascular debris. It also includes a reinfusion catheter for delivering filtered blood back to the patient.

“This is a larger device used for directly sucking large volumes of clot from the body. The blood is then recirculated back into the patient,” Moriarty said. “This can be used for treatment of blood clots in the pelvis, or in the chest, and particularly is very good for removing blood clots from within the heart.”

The device is approved for use during extracorporeal bypass.

BiO2 Angel Catheter

Inferior vena cava (IVC) filters are another technology that are sometimes used in PE treatment, but which are controversial for this indication, Rosenfield said.

“We try to be careful about when to place a filter,” Rosenfield said. “If it is a large, bulky thrombus in the great veins of the leg or in the common femoral vein, then we have a lower threshold to place a filter, but they can also be problematic. We try to be thoughtful about where we place a filter.”

Tapson said a new device, the BiO2 Angel Catheter (BiO2 Medical), recently received FDA approval.

“This is a triple lumen infusion-combined IVC filter,” Tapson said. “We did a large study here in the U.S., and we’re writing up the manuscript now. We’re hoping to publish it soon, but the FDA, through its early feasibility program, has already approved the device.” It is indicated for short-term prevention of PE in high-risk patients.

Rosenfield said the fact that the BiO2 catheter allows the placement of a temporary (for up to 1 month) filter will likely have interesting implications for the future use of filters.

“I think this is going to change the game a little bit,” he said. “People might have a lower threshold to put filters in now because they know they will have to pull it out.” – by Jennifer Byrne

There are several endovascular technologies available for use in treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE). They work quite differently from one another and many are used off-label in the United States. Cardiology Today’s Intervention asked experts to explain the available different devices.

EkoSonic Endovascular System

One of the more commonly used endovascular devices for DVT intervention is the EkoSonic Endovascular System (EKOS Corp.). This system uses a thrombolytic drug through a catheter, and additionally includes a device which generates low-intensity, high-frequency ultrasonic waves to accelerate the process.

“You basically deliver these catheters into the lung and there is an ultrasound core wire that fits in the lumen of this catheter; the wire has little ultrasound transducers that when spaced apart, may deliver this high-frequency ultrasound,” Victor F. Tapson, MD, professor of medicine, pulmonary and critical care at Cedars-Sinai Medical Center, Los Angeles, said. “You put normal saline through a coolant port that’s connected to this lumen, and this helps to diffuse the heat energy that’s generated. Then, you have these infusion catheters, and you deliver the ultrasound while you deliver low-dose thrombotic therapy.”

Kenneth Rosenfield, MD, MHCDS, FACC, FSCAI, section head of vascular medicine and intervention at Massachusetts General Hospital, said he has frequently used the EkoSonic system with good results. “Most of the time when [choosing catheter-directed thrombolysis (CDT)], we’re using EKOS catheters,” he said. “We have been very satisfied, very impressed that this is an effective therapy. Usually it’s 1 mg per hour in each side, and within 4 to 6 hours, patients feel different. They describe a lifting of the pressure on their chest, they’re breathing easier and their heart rate slows down.”

The system has been evaluated in two clinical trials, SEATTLE II and ULTIMA. In the ULTIMA trial, which was a randomized controlled trial, therapy with the EkoSonic Endovascular System was found to be superior to heparin monotherapy in reversing right ventricular dilatation at 24 hours. The SEATTLE II trial, which was a prospective, single-arm, multicenter trial, found that therapy with the system reduced RV dilatation, pulmonary hypertension and anatomic thrombus burden, and lessened intracranial hemorrhage in patients with acute massive and submassive PE.

“This technique is the one we’re getting the most data on. It’s the one that’s FDA-approved for PE, and I will give EKOS credit for continuing to try to get data and help us advance this field,” Tapson said. “One of the problems with this field is that we don’t have enough randomized clinical trial data. The ULTIMA study was a randomized study; SEATTLE II was single-arm, but 150 patients. These are the best we have.”

Inari FlowTriever

Another system for the endovascular treatment of patients with acute PE is the FlowTriever Retrieval/Aspiration System (Inari Medical). This system uses a catheter-based mechanical thrombectomy device to percutaneously retrieve emboli from the peripheral vasculature.

Three discs “are expanded in the pulmonary artery. They engage the clot, and are then sucked back in with a lever-type device into a 20F sheath,” Rosenfield said. “The 20F sheath extracts, the clot comes back with the FlowTriever discs, and you remove the device. Nothing completely removes the thrombus. All you need to do is relieve the major obstruction, and the patients get better. The rest of the thrombus is dissolved by itself.”

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Rosenfield and Tapson are co-principal investigators of the FLARE study, a prospective, multicenter, single-arm study assessing the FlowTriever in 150 patients with acute PE. The study will be conducted at up 20 clinical sites in the United States.

“We don’t have a lot of data yet,” Tapson said. “This device has been used in a number of cases around the country, but the exciting part now is again getting a study underway to look at FDA approval.”

The device is FDA-approved to treat emboli in the peripheral vasculature, but not to treat PE.

Penumbra Indigo System

The Indigo Mechanical Thrombectomy System (Penumbra Inc.) is a trackable thrombectomy system featuring a proprietary aspiration pump that provides suction through a catheter.

According to John Moriarty, MD, a specialist in vascular and interventional radiology at UCLA, this system originated in stroke therapy.

“The original devices were used for removing blood clots in the brain. The catheter was advanced into the blood clot and then attached to a vacuum suction, which directly sucked the clot out of the blood vessel and removed it,” he said. “The Indigo device uses the same basic idea, but uses larger catheters with different properties, such as different angles on them, to remove the blood clots from the venous system. It is good at removing clots from places that are difficult to reach because it is a very torque-able, very deliverable catheter.”

Keith M. Sterling, MD, from Inova Alexandria Hospital, Alexandria, Virginia, said the system has been particularly effective in patients who require catheter-based clot removal but have a contraindication to thrombolytic agents. “Striking results have been achieved in patients with massive and submassive PE with performing an ‘on the table’ treatment, with reversal of right heart dysfunction and stabilization of the patient’s hemodynamic status.”

The device is FDA-approved to treat emboli and thrombi in the peripheral arterial and venous systems, but it is not approved for use in the coronary vasculature.

AngioJet System

The AngioJet Thrombectomy System (Boston Scientific) is a device used in rheolytic thrombectomy, a technique that aspirates the thrombus locally. While the system has been used to treat PE, it is not FDA-approved for this indication, and the FDA has issued a black box warning for its use in patients with acute massive PE.

“It’s a device that sends pressurized saline to the catheter tip, and these saline jets travel backward to create a little pressure zone, causing a vacuum effect,” Tapson said. “The thrombus is drawn in through this inflow window, and the jets push the thrombus back down the catheter, so it’s evacuated.”

Rosenfield said he has personally been cautious in using the AngioJet System, but some physicians have reported positive outcomes associated with use of the technology.

PAGE BREAK

“Patients have developed bradycardia and hypotension with this device. I’ve been a little bit cautious about using it, but I did see someone present a series of 50-odd cases with very good results,” he said.

The device is approved for treatment of DVT and other peripheral conditions.

Vortex AngioVac device

Another novel technology that is currently used to treat patients with acute DVT or PE is the Vortex AngioVac device (AngioDynamics). This device utilizes a cannula and an extracorporeal unit with a filter for pump-supported removal of intravascular debris. It also includes a reinfusion catheter for delivering filtered blood back to the patient.

“This is a larger device used for directly sucking large volumes of clot from the body. The blood is then recirculated back into the patient,” Moriarty said. “This can be used for treatment of blood clots in the pelvis, or in the chest, and particularly is very good for removing blood clots from within the heart.”

The device is approved for use during extracorporeal bypass.

BiO2 Angel Catheter

Inferior vena cava (IVC) filters are another technology that are sometimes used in PE treatment, but which are controversial for this indication, Rosenfield said.

“We try to be careful about when to place a filter,” Rosenfield said. “If it is a large, bulky thrombus in the great veins of the leg or in the common femoral vein, then we have a lower threshold to place a filter, but they can also be problematic. We try to be thoughtful about where we place a filter.”

Tapson said a new device, the BiO2 Angel Catheter (BiO2 Medical), recently received FDA approval.

“This is a triple lumen infusion-combined IVC filter,” Tapson said. “We did a large study here in the U.S., and we’re writing up the manuscript now. We’re hoping to publish it soon, but the FDA, through its early feasibility program, has already approved the device.” It is indicated for short-term prevention of PE in high-risk patients.

Rosenfield said the fact that the BiO2 catheter allows the placement of a temporary (for up to 1 month) filter will likely have interesting implications for the future use of filters.

“I think this is going to change the game a little bit,” he said. “People might have a lower threshold to put filters in now because they know they will have to pull it out.” – by Jennifer Byrne