Interventional radiology


Interventional radiology is a medical subspecialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs both diagnostic and therapeutic procedures through very small incisions or body orifices. Diagnostic IR procedures are those intended to help make a diagnosis or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an imaging contrast agent into a hollow structure, such as a blood vessel or a duct. By contrast, therapeutic IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement, and angioplasty of narrowed structures.
The main benefits of interventional radiology techniques are that they can reach the deep structures of the body through a body orifice or tiny incision using small needles and wires. That decreases risks, pain, and recovery compared to open procedures. Real-time visualization also allows precision guidance to the abnormality, making the procedure or diagnosis more accurate. These benefits are weighed against the additional risks of lack of immediate access to internal structures, and the risks of radiation exposure such as cataracts and cancer.

Types of interventional radiology

Common elements

Interventional radiology is a set of techniques that allows access to the internal structures of the body through body orifices or very small incisions and guidance with medical imaging. Regardless of the reason for the intervention, the procedure will likely use common elements such as a puncture needle, guidewires, a sheath, and catheters.
Also common to all intervention radiology procedures are the medical imaging machines that allow the healthcare provider to see what is occurring within the body. Some use x-rays and some do not. In each case, the images created may be modified by computer to better visualize the structures as is in the case with digital subtraction angiography, CT and MRI, or the display of the images improved with virtual reality or augmented reality presentation.

Diagnostic interventional radiology

Vascular
Biliary intervention
Catheter placement
Ablative
Genitourinary

Biliary intervention

Gastrointestinal Bleeds

The treatment of a gastrointestinal bleed can range anywhere from monitoring an asymptomatic bleed to supporting and maintaining the hemodynamic function of the patient. The role for the interventional radiologist is to offer patients an image-guided, minimally invasive procedure to alleviate a condition that could be otherwise be potentially life-threatening.
The avenue for the interventional radiologist to dictate the clinical course of a GI bleed is largely influenced by location of bleed, overall patient health and other conditions the patient may have, most notably heart and liver functions. For most cases, collaboration between the gastroenterologist and interventional radiologist optimizes patient outcome but again, is largely dictated by anatomical location of the GI bleed. If a patient is evaluated and determined to be a candidate for an interventional procedure, then the bleed is often treated by embolization. Embolization is a process in which the interventional radiologist accesses the culprit bleeding vessel via a small catheter and interrupts blood flow to the site of bleeding via various mechanisms. Side effects of this procedure are minimal but there is a risk of bleeding and infection—though much less than the equivalent surgical procedure. When successful, the procedure often eliminates the bleed and patients can walk after a few hours of rest.

Hepatobiliary

A transjugular intrahepatic portosystemic shunt is a procedure an interventional radiologist performs to create a shunt between the hepatic inferior vena cava and the portal vein, a vessel that returns blood from the intestines to the liver. The portal vein is the site where hypertension can produce a myriad of deleterious effects throughout the liver and small or large intestine.
Primarily, a TIPS functions to alleviate two different conditions: an emergent/life-threatening GI bleed or ascites caused by too high of blood pressure in the portal vein that is otherwise uncontrolled by diet and medications.
The workup for the procedure is straightforward and the interventional radiologist performing the procedure often orders several tests to assess how well the patient will tolerate the procedure. These are often simple blood tests, and an ultrasound of the heart and liver. The procedure is often well tolerated and can result in a permanent reduction or elimination of symptoms. The procedure can take anywhere between 15 minutes to an hour and has lower risks of bleeding or infection compared to an equivalent surgical procedure.
A TIPS may cause temporary confusion or worsening of liver/heart function. The degree of these two side effects largely depend on the health of the patient's heart and liver prior to the procedure and the risk-benefits of the procedure must be thoroughly discussed with their interventional radiologist before beginning. If the post-procedural consequences are more troublesome to the patient than their initial symptoms the artificial conduit created by the procedure can be reversed if the post-procedural side effects outweigh those caused by the prior conditions.

Biliary disease

In addition to normal normal liver tissue, the liver has three main vessels traversing it: arteries, veins and bile ducts. While bile is made in the liver and stored in the gallbladder, the bile eventually passes into the GI tract through the hepatic, cystic and common bile ducts. Any condition that prevents the normal flow of bile from the liver, through these bile vessels and into the GI tract can cause a condition called jaundice.
While jaundice can be caused by a few viruses that the human body can naturally clear, jaundice in the setting of an obstruction is usually caused by a cancer and can result in intolerable itching and a worsening of liver function that can be life-threatening. Depending on a patient's condition, this type of obstructive jaundice can be alleviated with surgery or chemotherapy but if these measures fail to restore proper flow of bile, an interventional radiologist can perform a procedure called a percutaneous transhepatic cholangiography.
A PTC is an outpatient procedure lasting anywhere from 15 minutes to an hour where an interventional radiologist accesses the patient's bile duct system with a needle through the skin and liver under imaging guidance. Using fluoroscopy to guide a wire through the bile duct system and into the GI tract, essentially restoring the normal flow of bile. If the patient's GI tract cannot be accessed due to the obstruction, the catheter can be placed to drain the bile duct system into a bag that the patient can wear during daily activities. Risks of this procedure include bleeding and infection but these are much lower than an equivalent surgical procedure.

Genitourinary diseases

Benign prostatic hyperplasia

, or BPH, is a noncancerous condition that commonly affects men over the age of 50. The prostate gland enlarges and compresses the adjacent urethra, making it difficult for men to control frequency and/or urgency of urination. First line therapy involves medication, though long-term treatment for symptoms that are persistent despite medical optimization typically involves transurethral resection of the prostate as the "gold standard" of care. However, TURP can lead to urinary incontinence or permanent male infertility and may not be the ideal procedure for a certain subset of patients. For those reasons, a physician may recommend undergoing a treatment known as prostate artery embolization.
Patients typically go home the same day as the procedure and can expect to feel some symptom relief in a matter of days. Though rare, risks of PAE include unintentional embolization of nearby blood vessels, which can result in loss of blood flow to surrounding areas of the bladder or rectum.
Data suggests that TURP may have higher rates of symptom resolution at 1 and 6 months, but PAE appears to provide lower risks of complications more commonly associated with surgery, such as infection.

Kidney stone disease

can be present along any part of the course of the urinary tract from the kidneys to the urethra. The most common symptoms, whether in men or women, are sudden onset, intense flank pain accompanied by blood in the urine. Most kidney stones pass spontaneously, but larger ones are less likely to, and can cause severe pain or infection.
The interventional radiologist plays a large clinical role in the treatment of kidney stones that are unlikely to pass on their own. The gold standard of treatment for these types of stones is surgical removal. However, some patients have an infected stone and are simply too ill for an operative surgical removal. In these instances, the mainstay of IR treatment is a percutaneous nephrostomy tube. This is a procedure where a small caliber catheter is placed through the skin and into the urinary collecting system upstream of the stone. This procedure not only drains any infection, often bringing about a precipitous improvement in the patient's symptoms but also diverts urine—thus giving the patient more time to recover before definitive surgical treatment.

Varicocele

A varicocele is defined as an enlargement of the veins within the scrotum, most commonly occurring on the left side due to anatomical reasons. When this happens, blood can stagnate within these dilated veins and cause temperature fluctuations within the testicle itself. The exact cause to this condition remains unknown and an ill-favored sequela can be male infertility.
The mainstay of treatment for this condition within the field of interventional radiology is varicocele embolization. An embolization, within the context of this procedure, results in the interruption of venous blood flow. The interruption of blood flow abates venous dilation of blood that can lead to impaired testicular temperature regulation and theoretically improve infertility. The physician accesses the dilated scrotal veins with a small catheter via a vein in the groin and embolize the varicocele. Patients often tolerate this procedure well and are able to return home the same day.

Neurological intervention

Acute ischemic stroke

About 87% of all strokes are ischemic strokes, in which blood flow to the brain is blocked. A clot-busting medication such as tissue plasminogen activator can be used in a controlled hospital setting to dissolve the clot and help restore blood flow to the damaged area of the brain. Certain patients who are suffering from an acute ischemic stroke may be candidates for endovascular therapy. Endovascular therapy is a procedure performed by neurointerventionalists to remove or dissolve the thrombus and restore blood flow to parts of the brain. Using a catheter that is directed through the blood vessels in the arm or leg up to the brain, the interventionalist can remove the thrombus or deliver drugs to dissolve the thrombus. These procedures are referred to as mechanical thrombectomy or thrombolysis, and several factors are considered before the procedure is completed.
People who may be eligible for endovascular treatment have a large vessel occlusion, which means the thrombus is in an artery that is large enough to reach and there are no contraindications such as, a hemorrhagic stroke, greater than six hours since onset of symptoms, or greater than 24 hours in special cases. Hospitals with comprehensive stroke centers are equipped to treat patients with endovascular care.
Long-term care after an ischemic stroke is focused on rehabilitation and preventing future blood clots using anticoagulant therapy. Patients work with specialists from fields such as physical therapy, occupational therapy, and speech therapy to complete recovery.

[Intracranial aneurysm]

Although there are no clearly defined recommendations on treatment of asymptomatic aneurysms, all symptomatic unruptured brain aneurysms should be treated. Endovascular therapy is an effective treatment for select cases. During this treatment, an interventional radiologist inserts a catheter into the patient's leg and uses it to guide a coil through blood vessels to the site of the aneurysm. The coil induces clotting within the aneurysm, which reduces the risk of rupture. Multiple coils may be used depending on the size. Imaging studies help characterize the aneurysm to decide the best course of treatment, whether endovascular coiling or surgical clipping. Endovascular coiling is associated with a reduction in procedural morbidity and mortality over surgical. For cases of ruptured aneurysms, emergent treatment is based on the type of aneurysm, and may use a combination of techniques. Conservative therapy focuses on minimizing modifiable risk factors with blood pressure control and smoking cessation.

[Cerebral arteriovenous malformation]

Arteriovenous malformations are abnormal blood vessel structures in which an artery connects to a vein via an abnormal channel. This creates a high flow system that puts the vessel at risk of rupture. Ruptured AVMs require emergency management of the patient; unruptured AVMs require expert consultation to discuss the risks and benefits of treatment. Current treatment options include conservative management, surgical resection, stereotactic radiosurgery, endovascular embolization, or combinations of these treatments. Endovascular embolization is a technique used by neurointerventionalists in which particles, glue, or coils are lodged inside the AVM to prevent blood flow through the abnormal channel. During this treatment, an interventional radiologist guides a catheter through a blood vessel accessed from the patient's leg to the site of the AVM. The particles, glue, or coils induce clotting within the malformation, which reduces the risk of rupture.

Pain management

Joint and local injections

Utilizing image guidance, local anesthetics and/or long-acting steroid medications can be directly delivered to localized sites of pain. The use of image guidance helps to confirm appropriate needle placement. This includes common imaging modalities used in joint injections: ultrasound, fluoroscopy and computerized tomography.
Facet joints

Chronic pelvic pain

, which includes vertebroplasty and kyphoplasty, are similar spinal procedures in which bone cement is injected through a small hole in the skin into a fractured vertebra to try to relieve back pain caused by a vertebral compression fractures. It was found ineffective in treating osteoporosis-related compression fractures of the spine. The people in both the experimental and placebo groups reported improvement in their pain, suggesting that the benefit is related to the placebo effect., routine use is thus not recommended.

Sarcoplasty

Procedures performed

Interventional oncology procedures are commonly applied to treat primary or metastatic cancer. IO treatments may be also offered in combination with surgery, systemic chemotherapy/immunotherapy, and radiation therapy to augment the therapeutic outcome. A variety of interventional oncological treatments for tumors arise:
Vascular Disease refers to disorders of the vasculature or circulatory system, most commonly involving the arteries, veins and lymphatics. The symptoms related to vascular disease can range from asymptomatic, bothersome symptoms or limb and/or life-threatening conditions.
Vascular and Interventional Radiologists are at the forefront of treating a wide variety of vascular diseases.

Basics of vascular intervention

Since its development by Charles Dotter when he did a percutaneous peripheral vascular revascularization procedure for the first time on January 16, 1964 on Laura Shaw, Vascular & Interventional Radiology distinguished itself from earlier approaches to vascular disease by the use of medical imaging to guide endovascular therapies. The Seldinger technique is the basic principle that underlies endovascular procedures. Briefly, this involves using a needle to puncture a target vessel, then using a series of small to pass various tools inside for treatment. When these minimally-invasive techniques can be used, patients avoid the need for larger surgical exposure to treat diseased vessels. Though numerous factors can affect patient's post-operative course, in general an endovascular approach is associated with a more rapid recovery time compared to a traditional open vascular surgery.
Over the past few decades, many endovascular procedures have been developed and refined. Numerous tools are at the disposal of modern Vascular and Interventional Radiologists to perform these procedures, and developing new tools is a burgeoning focus of international research.
While some Interventional Radiology endovascular procedures are highly specialized, a few standard techniques apply to most:
  1. Angiography: Sometimes referred to as traditional angiography, catheter angiography or digital subtraction angiography A small needle is inserted into a blood vessel, then exchanged for a catheter over a wire. The catheter is directed at the vessel to be studied, and contrast is directly injected to evaluate the lumen under video X-ray. This is an older technique than modern CT Angiography or MR Angiography, but provides unique advantages. With a catheter in place, provocative maneuvers can be performed such as breath holds or instillation of vasodilators, to evaluate a patient's blood flow dynamically. This can reproduce symptoms and identify functional abnormalities in a vessel that a static CT or MR imaging cannot. Angiography provides the basis for all endovascular therapy.
  2. Balloon Angiography: The foundational IR procedure. Small balloons can be inflated inside a narrowed vessel to open it. These can then be safely deflated and removed. Some balloons have a specialized surface material, such as fine razor blades to crack the plaque or instill a coating of medicine that keeps the vessel open longer.
  3. Stents and stent-grafts: are used to provide a scaffold along a segment of diseased vessel. These are available in a variety of sizes to accommodate placement in vessels throughout the body from head to toe. Endografts are stents with fabric covering that are used for the treatment of bleeding or aneurysms. These devices typically come folded up very small on a scaffold, or delivery device, such as a balloon. Stents then expand into pipe-like cylinders to support a vessel wall and keep the pathway for blood flow as large as possible. Some stents are bare-metal, allowing blood to leak through the walls of the stent, while others have a thin covering that keeps flow moving through only from one open end to the other. These can be used for a variety of applications depending on the vessel and the nature of the disease. Sometimes multiple stents are deployed end-to-end or side by side to maintain laminar flow. Like balloons, some stents come coated with medicine to help prevent the treated vessel from closing again.
  4. Embolization: The goal of embolization is to decrease or stop flow only in a target vessel, while avoiding cutting off the flow to nearby non-target vessels. This can be performed to stop active bleeding to limit anticipated blood loss or to cut off blood supply to either an abnormal vessel or abnormal structure There are many embolic agents available, from metallic plugs and coils to various biologically compatible particles and glues. Further information about these embolic agents can be found . Depending on the clinical situation, embolization can be temporary or permanent.
  5. Thrombolysis and Thrombectomy: The body forms blood clots as a natural protective mechanism against bleeding. However, when arising outside this context, blood clots can wreak havoc in the human body including disabling strokes. Thrombolysis is the process of breaking down blood clots, by injecting them with powerful medications. Thrombectomy involves using a device to remove the clot directly.
The goal of endovascular therapy is to revascularize an affected or diseased vessel.

Arterial disease

are the component of the circulatory system that carry oxygenated blood away from the heart to the vital organs and extremities. Arteries have relatively thick, muscular walls, composed of multiple layers, because they transport freshly oxygenated blood through the body at relatively high pressures. Arterial diseases can affect one or multiple layers of the artery wall.
The aorta is the largest artery in the body, and the major aortic branches continue to divide multiple times, giving way to smaller arteries, muscular arterioles and thin-walled capillaries. In contrast to arteries, capillaries have thin single-layered walls, so oxygen and nutrients can be exchanged with tissues in capillary beds before the de-oxygenated blood is carried away by the venous system.
Perfusion refers to the flow of oxygen and nutrient rich blood into the capillary beds of the muscles and organs, this is critical for their function. The lack of adequate perfusion is referred to as ischemia and is typically the cause of symptoms related to vascular disease. The goal of revascularization therapies, whether endovascular or surgical, is to re-establish or optimize perfusion and stop ischemia.
Atherosclerosis refers to a progressive narrowing of the arteries due to atheroma, derived from the Greek word for gruel or porridge. Atheromatous plaque is a mixture of fat and inflammatory debris that sticks to the inner walls of an artery. Plaque can be soft or become firm as it accrues layers of calcium, a byproduct of chronic inflammation. Atherosclerosis has no single cause but many recognized risk factors. Some risk factors are modifiable, and others are not. Age and genetic predispositions are an example of non-modifiable risk factors. Medical management of atherosclerosis aims to address the many other known modifiable risk factors, such as smoking, diet, exercise as well as blood sugar levels in patients with diabetes. Using medications to control blood pressure and cholesterol have also been shown beneficial.
Atherosclerosis is described, evaluated, and treated differently depending on the affected artery, as described below. However, multiple studies have shown strong correlations between the different types of atherosclerosis. In particular, patients with Peripheral Arterial Disease have an increased risk of Coronary Artery Disease, and severe Peripheral Artery Disease symptoms can be a predictor of cardiac related mortality. The majority of patients begin to develop symptoms from ischemia around middle age, even though vessel narrowing can develop silently and slowly over decades. Unfortunately, sudden cardiac death or stroke can be a patient's first sign of vascular disease. Therefore, controlling risk factors is crucial in those with known atherosclerosis to prevent progression of disease, and screening is recommended by some Vascular Disease Specialists for those at increased risk, such as those with diabetes, smoking or a strong family history of cardiovascular disease.
Screening tests typically use the non invasive evaluation called the Ankle-Brachial Index, which compares the blood pressure between the arm and the ankle. This can help detect narrowing in the major vessels of the chest, abdomen, pelvis, and legs. CT scans of the heart with evaluations of coronary artery calcium are also used in some instances to stratify risk of coronary artery disease.
Historically, open vascular surgical approaches were required for all critically advanced atherosclerotic disease. An endarterectomy is a large operation, where blood flow is temporarily stopped using clamps, the vessel is cut open, the plaque removed and then the vessel resealed. If an occlusion is too dense or complex, a bypass could also be performed, where two segments of vessel are bridged by an additional vein or synthetic graft.
Modern endovascular approaches to treating atherosclerosis can include combinations of angioplasty, stenting, and atherectomy.
Peripheral Arterial Disease is most often a result of atherosclerosis and affects the arteries of the lower extremities, those below the aortic bifurcation. A hallmark symptom is claudication, or progressive pain in a limb associated with activity, due to ischemia. As the perfusion to a limb diminishes further pain in the foot can occur even at rest and in fact the tissues of the foot can even die.
There are several systems for staging PAD, but an often used scale is the revised . Plaque and blood flow can be evaluated using ultrasound, CT Angiography, MR angiography and catheter based angiography to establish anatomic segments of disease. The severity of ischemia can be evaluated by correlating symptoms and non-invasive physiologic vascular studies including toe pressures, TCPO2, and skin perfusion studies.
Certain monitored exercises, such as walking regimens, have been shown to significantly improve walking distance especially when used consistently for at least 6 months. When medical management fails, Vascular Interventional Radiologists can attempt to restore blood flow to extremities using angioplasty and stenting. Sometimes repeat interventions are required. The goal of therapy is to maintain perfusion, avoid amputation and preserve the limb structure and function.
  1. Critical Limb Ischemia is a severe variant of PAD characterized by rest pain or tissue loss. Each year this affects just under 1% of the population, but develops in approximately 11% of PAD patients. Symptoms develop due to chronic ischemia from vessel plaque burden, which builds up over time. Rest pain is a continuous burning pain in the limb that is aggravated by elevating it and improved by dangling over the bed as the perfusion is so poor that it becomes gravity dependent. Tissue loss refers to arterial insufficiency ulcers, which can progress to frank gangrene. Arterial ulcers are classically painful and located on the distal aspect of the extremities. A diagnosis of CLI incurs a higher risk of amputation and death This is a serious condition that requires multi-modality treatment. The goal of Vascular Interventional Radiology and others who work in Limb Salvage is to minimize tissue loss by preserving direct blood flow to the affected limb by treating vessel blockages, controlling any infection and optimizing wound care. Increasingly, this can be accomplished with primary endovascular therapies before open surgery is considered.
  2. Acute Limb Ischemia results when blood flow to an extremity is abruptly cut off. It occurs most commonly in those with a history of atrial fibrillation or underlying PAD/PVD. Unlike chronic ischemia, which the body can partially adapt to, ALI is an emergency that can result in an amputation or even death if not treated in hours. It is typically due to an embolus from the heart or a thrombus that develops in a pre-existing area of narrowed artery. Once diagnosed clinically, CT or MR Angiography may be used to evaluate the cause and extent of disease. Vascular Interventional Radiologists may use thrombectomy devices or clot dissolving medications to remove or dissolve the clot. Surgical options include open thrombectomy and even vascular bypass.
  3. Carotid Atherosclerosis involves the major branch arteries that provide blood to the brain. Carotid artery disease incurs an increased risk of stroke by two different mechanisms, either from limiting overall blood flow or more often by showering pieces of plaque or clot deep into the small vessels in the brain. Either can result in degrees of cerebral ischemia. Carotid artery disease can be typically addressed with open surgical techniques or though endovascular stenting.
  4. Chronic mesenteric ischemia can produce severe pain with eating and result in food fear and weight loss. These vascular disorders can be repaired by endovascular approaches using angioplasty and stenting.
  5. Renal arterial ischemia can contribute to hypertension, which can be severe and refractory to medical therapy.
  6. Coronary Artery Disease involves the arteries supplying blood to heart muscle. Coronary ischemia results in myocardial infarction, also known as a heart attack. The coronary arteries were one of the earliest widely accepted applications of angioplasty and stenting developed by cardiology and interventional radiology.
  7. Aortoiliac Occlusive Disease is a constellation of symptoms due to significant occlusion of the distal aorta and common iliac arteries, most commonly by atherosclerotic disease The classic symptoms include buttock claudication and erectile dysfunction, with decreased femoral pulses. Additional symptoms of Critical Limb Ischemia can be present. Both surgical and endovascular approaches to revascularization can be considered.
Aneurysm refers to pathologic dilation of an artery to greater than 1.5 times its normal size. True vascular aneurysms are due to degenerative processes in the wall of the artery. Aneurysms can be solitary or multiple and are sometimes found in association with various clinical syndromes, including forms of vasculitis or connective tissue diseases. Aneurysms are typically classified by major shapes, either fusiform or saccular. Ectasia is another broad term for an enlarged vessel, but is not necessarily pathological. Rupture is a dreaded complication of aneurysms that can lead to extensive, difficult to control bleeding. Aneurysms can also clot, or thrombose, and rapidly occlude the involved vessel, leading to acute distal ischemia.
  1. Aortic Aneurysms include thoracic, abdominal or thoracoabdominal. Treatment strategies are customized depending on the location, size, rate of growth and extent of the aneurysm as well as the medical comorbidities of the patient. For example, an intact, small but slowly growing aneurysm may be safely monitored with serial imaging for months or years before elective repair is considered. Elective endovascular aortic grafting is now routinely attempted when possible. Endovascular Aortic Repair refers to treatment of an abdominal aortic aneurysm, while Thoracic Endovascular Aortic Repair is performed on the thoracic aorta. A ruptured aneurysm may be taken emergently for open, endovascular or combination repair.
A variety of endovascular grafts are available, and each has advantages and disadvantages depending on the characteristics of the aneurysm and patient
  1. Aneurysms refers to aneurysms in the arms and legs. These can typically be evaluated and monitored with vascular ultrasound, CT angiography and MR angiography. Popliteal aneurysms are associated with distal embolization and are also associated with concurrent contralateral popliteal artery aneurysms and abdominal aortic aneurysms. When amenable, can include endovascular stenting or surgical bypass.
  2. Visceral Aneurysm affect the vessels that supply the solid organs. Similar to other aneurysms, treatment depends on several factors including size, location, shape and growth. can usually be performed with less morbidity when compared to open surgical techniques.
  3. Intracranial Aneurysms arise in the arterial supply of the brain. Endovascular approaches to treatment include stenting and coiling and are preferable in most cases since clipping and resection require a surgical craniotomy. Rupture of intracranial aneurysms can have devastating clinical effects. For further discussion, refer to the Neuro-Interventional Radiology Section.
  4. Pseudoaneurysm is when there is not all 3 layers surrounding the artery. These structures can technically be considered a type of contained bleed. They are most often due to focal damage to a blood vessel, which could be the result of trauma, infection or inflammation. Splenic artery pseudoaneurysms, for example, may develop as a result of pancreatitis. In some cases, pseudoaneurysms of the femoral and radial arterials can be a complication of arterial access for endovascular procedures. Depending on the size and location of the pseudoaneurysm, it may be treatable with minimally-invasive Interventional Radiology methods, though some particularly the infected ones may require open surgery.
Dissection refers to a tear in the inner layer of the arterial wall. Blood pumps into this defect and dissects its way between the layers in the wall of an artery, creating a false channel separate from the true arterial lumen. Dissections can develop due to trauma, spontaneously due to high blood pressure and native vascular disease, or in some cases as a complication of prior surgical or endovascular treatment.
When an arterial dissection expands, it can restrict normal flow through the affected artery or potentially block the origin of a branch vessel- this can compromise distal perfusion in either case. When acute and symptomatic, this is an emergency that requires prompt treatment.
However, as medical imaging has improved, chronic, asymptomatic dissections have also been discovered, and in some cases these may be safely managed with blood pressure control, follow-up imaging and proper counseling for the warning signs of potential ischemia.
Dissections can occur in any artery and are named for their vessel of origin. Aortic dissections can be further classified and treated depending on whether they involve the thoracic aorta, the abdominal aorta or both. Classic pain related to acute aortic dissections is described as “tearing” or “ripping” and possibly radiating to a patient's back. Acute aortic dissection can be difficult to diagnose but is more common than aortic aneurysm rupture.
Thoracic aortic dissections are further characterized with the . Type A dissections involve the root and ascending aorta. These require prompt treatment, which currently is mostly surgical in nature. Type B dissections begin in the distal aortic arch beyond the left subclavian artery origin, and may often be addressed with pain medication and blood pressure control. If the type B aortic dissection results in poor circulation to the intestines, kidneys or legs it often requires urgent endovascular repair with endografts and/or fenestrations. If a type B aortic dissection has ruptured, or has features that indicate impending rupture, they are urgently repaired too.
Dissections can also arise in virtually any other artery. Carotid artery Dissection, for example, places patients at increased risk for stroke and may extend further into the blood vessels within the brain. Vertebral Artery Dissection are less common but also dangerous for similar reasons. Mesenteric Artery Dissection may limit the blood supply to the intestines. can decrease blood flow to the kidneys and contribute to hypertension. Peripheral Arterial Dissections can be found elsewhere in the arms and legs. These dissections can occur primarily due to focal traumas, underlying vascular disease, or as an extension of a larger, complex aortic dissection that tears further into these smaller branches.
Treatment of dissections depends on several factors, including the location, extent, how long it has been developing and whether it is limiting perfusion. Surgical approaches to dissections can include reconstructing the aorta, surgical bypass and surgical fenestration. Like other arterial disorders, endovascular approaches to dissection such as and percutaneous can be utilized- either primarily or in combination with surgery depending on the complexity of the dissection.
is an advanced focal form atherosclerosis, most often encountered in the aorta. It starts as a small plaque in the inner-most layer of the aorta called the intima, but the inflammatory process ulcerates and penetrates through this layer into the media. While PAU is considered a distinct entity, many think this is a precursor lesion to dissection or aneurysm. Along with Intramural Hematoma, Aneurysm and Dissection, PAU is recognized as one of several Acute Aortic Syndromes—a spectrum of related conditions correlated to potential aortic rupture. They thus have a high potential morbidity and mortality, and should at least be followed closely.
Acute or Active Bleeding can occur throughout the human body due to a variety of causes. Interventional Radiologists can address bleeding with embolization, usually with small plastic particles, glues or coils. Traumatic rupture of a blood vessel, for example, may be addressed this way if a patient is at risk of fatal bleeding. This has revolutionized medicine and interventional radiologists commonly treat refractory nose bleeds, excessive coughing of blood, intestinal bleeding, post-pregnancy bleeding, spontaneous intra-abdominal on intra-thoracic bleeding, bleeding related to trauma and post-surgical bleeding. In some instances where severe bleeding is anticipated, such as in complex surgery or the excision of a highly vascular tumor, Interventional Radiologists may embolize certain target blood vessels prior to the operation to prevent major blood loss.
Transplant Organs rely on healthy blood supply to survive. In some instances, the arteries that feed a transplant may narrow, typically where the donor vessel is sewn to the recipient. Interventional Radiologists evaluate the blood supply of these patient's and may use balloons or stents to open narrowed vessels and keep the transplant organ functional.

Venous disease

The veins of the human body are responsible for returning de-oxygenated blood back to the heart. Like a rock rolling down a hill, blood flows from the highest pressure to the lower venous pressure Unlike arteries, veins are thin walled and distensible, allowing them to accommodate large volumes of blood without significant changes in pressure. In fact, the venous system is so low pressure that veins have valves to keep blood from flowing backward. The motion of the human body helps pump blood through the veins- squeezing leg muscles while walking, for instance, helps push venous blood back up to the heart against the pull of gravity. Unfortunately, without this extra push some blood can sit stagnant in veins, leading to a multitude of clinical problems. The largest vein in the body is the vena cava. The superior vena cava drains blood from the top half of the body while the inferior vena cava drains blood from below the diaphragm. Elsewhere in the body, veins can be categorized into superficial, primarily associated with the skin and soft tissues, or deep veins, which drain muscles and organs.

Venous access

is a condition in which there is a progressive loss of kidney function. It has numerous recognized causes and risk factors. CKD affects approximately 14% of the world population, and over 600,000 people in the United States alone. There are five recognized stages of CKD, the fifth stage is also called End-Stage Renal Disease and invariably requires some form of renal replacement therapy.
Around the turn of the 20th century, breakthroughs in our understanding of renal physiology led many to believe that dialysis using artificial kidneys was a potential cure for renal disease. Over 100 years later, the only available curative, renal replacement therapy for CKD is kidney transplantation. However, many patients can live for decades utilizing dialysis.
Dialyzer technology initially outpaced the ability of clinicians to apply it to patients. In the 1920s, the first dialysis catheter was created using thin fragile glass tubes. Early methods required surgical incision to reach large vessels, which carried a large risk of major bleeding. The first somewhat permanent, reliable dialysis access, the Scribner Teflon Shunt, was invented nearly 40 years later and allowed a patient with kidney failure to survive 11 more years. As medicine and surgery have grown more sophisticated, more patients now live with chronic renal disease than ever before. The most common type of dialysis in the United States is hemodialysis, which can be performed through several types of vascular access. The Arteriovenous Fistula is the preferred method. are created surgically by directly connecting an artery and a vein, most commonly in the arm. An Arteriovenous Graft relies on the same principle but bridges the gap between the artery and vein with a medical-grade prosthetic shunt. Over time, altered flow mechanics can result in changes within the involved vessels. Vascular narrowing, thrombosis, aneurysms and pseudoaneurysms are commonly encountered complications over the life of an AVF or AVG. Interventional radiologists can use angiography to evaluate these structures and treat dysfunctional access with angioplasty, stenting, and thrombectomy. Most patients require regular evaluation and treatment to keep their access working. When possible, AVFs are preferred to AVGs due to their relatively lower complication rate and longer patency. The initiative works to promote physician and patient awareness about the benefits of first attempting hemodialysis through a fistula. There are a few devices that are being utilized by interventional radiologists to percutaneously create fistulas in a minimally invasive fashion.
Dialysis Catheters include temporary and tunneled large-bore central venous access lines placed for administering hemodialysis. When possible, these catheters are placed in the right internal jugular vein, but the left internal jugular and femoral veins may also be utilized. Temporary dialysis lines may be placed when patients are hospitalized and either too sick or at a high risk of bleeding. Permanent hemodialysis catheters are longer overall but a segment is tunneled through the skin of the chest, which lets the catheter lie flat and lowers the risk of infection.
Central Venous Access refers to a variety of intravenous catheters placed in patients requiring certain long-term medications. These are much smaller in diameter than dialysis lines, but are larger and longer than a standard intravenous line Examples include Hickman Catheters, Peripherally Inserted Central Cathethers, Tunneled small bore central venous catheters and Mediports. These lines differ in where they are inserted but are all placed under imaging guidance and adjusted so the end of the catheter sits in the vena cava adjacent to the heart. These catheter are designed to deliver strong medications, such as chemotherapy or prolonged courses of antibiotics, which are either dosed too frequently to keep placing new IVs or too irritating to small veins be injected through a standard IV.