Vascular bypass

Last updated
Vascular bypass
Other namesVascular graft
Specialty Vascular surgery, Cardiac surgery

A vascular bypass is a surgical procedure performed to redirect blood flow from one area to another by reconnecting blood vessels. Often, this is done to bypass around a diseased artery, from an area of normal blood flow to another relatively normal area. It is commonly performed due to inadequate blood flow (ischemia) caused by atherosclerosis, as a part of organ transplantation, or for vascular access in hemodialysis. In general, someone's own vein (autograft) is the preferred graft material (or conduit) for a vascular bypass, but other types of grafts such as polytetrafluoroethylene (Teflon), polyethylene terephthalate (Dacron), or a different person's vein (allograft) are also commonly used. Arteries can also serve as vascular grafts. A surgeon sews the graft to the source and target vessels by hand using surgical suture, creating a surgical anastomosis.

Contents

Common bypass sites include the heart (coronary artery bypass surgery) to treat coronary artery disease, and the legs, where lower extremity bypass surgery is used to treat peripheral vascular disease.

Medical uses

Cardiac bypass

Cardiac bypass is performed when the arteries that bring blood to the heart muscle (coronary arteries) become clogged by plaque. [1] [2] Such a condition may cause chest pain from angina pectoris or a heart attack. Dimensional aspects, material selection, and manufacturing methods influence mechanistic behaviours of artificial grafts and chosen to receive artery-like behaviour [3]

Leg (lower extremity) bypass

In the legs, bypass grafting is used to treat peripheral vascular disease, acute limb ischemia, aneurysms and trauma. While there are many anatomical arrangements for vascular bypass grafts in the lower extremities depending on the location of the disease, the principle is the same: to restore blood flow to an area without normal flow. [ citation needed ]

For example, a femoral-popliteal bypass ("fem-pop") might be used if the femoral artery is occluded. A fem-pop bypass may refer to the above- or below-knee popliteal artery. Other anatomic descriptions of lower extremity bypasses include:

Hemodialysis access

An arteriovenous graft serving as a fistula for hemodialysis access Blausen 0050 ArteriovenousGraft.png
An arteriovenous graft serving as a fistula for hemodialysis access

A vascular bypass is often created to serve as an access point to the circulatory system for hemodialysis. Such a bypass is referred to as an arteriovenous fistula if it directly connects a vein to an artery without using synthetic material.[ citation needed ]

Cerebral artery bypass

In the skull, when blood flow is blocked or a damaged cerebral artery prevents adequate blood flow to the brain, a cerebral artery bypass may be performed to improve or restore flow to an oxygen-deprived (ischemic) area of the brain. [5]

There are two main types of cerebral artery bypass: direct and indirect. Direct revascularization is also known as EC-IC bypass because it involves directly connecting an extracranial artery outside the brain to an intracranial artery inside the brain. This is also sometimes called STA-MCA bypass because the superficial temporal artery and the middle cerebral artery are the most commonly used arteries for the surgery. [6] STA-MCA bypass surgery has been shown to be ineffective in reducing the risk of ischemic stroke in an international, randomized clinical trial [7] led by clinical scientist Dr. Henry Barnett. Indirect revascularization involves placing part of an artery, in the case of EDAS (encephaloduroarteriosynangiosis), or part of a muscle, in the case of EMS (encephalomyosynangiosis), on the surface of the brain and allowing it to revascularize the brain through new vessel growth. Both types of indirect revascularization typically take 3-6 months to see effects. [8]

When several arteries are blocked and several bypasses are needed, the procedure is called multiple bypass. The number of bypasses needed does not always increase the risk of surgery, which depend more on the patient's overall health.

Evaluation

Prior to constructing a bypass, most surgeons will obtain or perform an imaging study to determine the severity and location of the diseased blood vessels. For cardiac and lower extremity disease, this is usually in the form of an angiogram. For hemodialysis access, this can be done with ultrasound. Occasionally, a CT angiogram will take the place of a formal angiogram.[ citation needed ]

Contraindications

The lack of an adequate venous conduit is a relative contraindication to bypass surgery, and depending on the area of disease, alternatives may be used. Medical conditions such as ischemic heart disease or chronic obstructive pulmonary disease that increase the risk of surgery are also relative contraindications. For coronary and peripheral vascular disease, lack of "runoff" to the distal area is also a contraindication because a vascular bypass around one diseased artery to another diseased area does not solve the vascular problem.[ citation needed ]

If a patient is deemed to be too high-risk to undergo a bypass, he or she may be a candidate for angioplasty or stenting of the relevant vessel.[ citation needed ]

Techniques

Standard techniques

Dogma in vascular bypass technique says to obtain proximal and distal control. This means that in a vessel with flow through it, a surgeon must have exposure of the furthest and nearest extents of the blood vessel in which the bypass is being created, so that when the vessel is opened, blood loss is minimized. After the necessary exposure, clamps are usually used on both the proximal and distal end of the segment. Exceptions exist where there is no blood flow through the target vessel at the area of proposed entry, as is the case with an intervening occlusion.[ citation needed ]

If the organ perfused by an artery is sensitive to even temporary occlusion of blood flow, such as in the brain, various other measures are taken.[ citation needed ]

ELANA

In neurosurgery, excimer laser assisted non-occlusive anastomosis (ELANA) is a technique use to create a bypass without interrupting the blood supply in the recipient blood vessels. This reduces the risk of stroke or a rupture of an aneurysm.

Risks and complications

Several complications can arise after vascular bypass. [9]

Risks of the bypass:[ citation needed ]

General risks of surgery:[ citation needed ]

Recovery

Immediately following coronary artery or neurosurgical vascular bypass surgery, patients recover in an intensive care unit or coronary care unit for one to two days. Provided that recovery is normal and without complications, they can move to a less intensively monitored unit such as a step-down unit or a ward bed. Depending on the extent of the surgery, recovery from a leg bypass may start from a step-down or ward bed. Monitoring immediately after bypass surgery focuses on signs and symptoms of bleeding and graft occlusion. If bleeding is detected, treatment can range from transfusion to reoperation. Later on in the hospital course, common complications include wound infections, pneumonia, urinary tract infection, and graft occlusion. [10]

At discharge, patients are often prescribed oral painkillers, and should be prescribed a statin and an anti-platelet medication if not contraindicated and their bypass was performed for atherosclerosis, (e.g., peripheral vascular disease or coronary artery disease). Some patients start feeling normal after one month, while others may still experience problems several months after the procedure. [10]

During the first twelve weeks after most bypass operations, patients are advised to avoid heavy lifting, house work, and strenuous recreation like golf, tennis, or swimming while their surgical wounds heal, particularly the sternum after coronary bypass. [10] [11]

Part of the recovery after any bypass surgery includes regular visits to a physician to monitor the patient's recovery. Normally a follow-up visit with a surgeon is scheduled for two to four weeks after surgery. The frequency of these visits gradually lessens as the patient's health improves. [10]

For vascular bypass operations performed for atherosclerosis, the operation does not cure the metabolic problem that led to the vascular disease. Lifestyle changes that include quitting smoking, making diet changes, and getting regular exercise are required to cure the underlying condition. [10] [12]

Related Research Articles

<span class="mw-page-title-main">Coronary artery disease</span> Reduction of blood flow to the heart

Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the cardiac muscle due to build-up of atherosclerotic plaque in the arteries of the heart. It is the most common of the cardiovascular diseases. Types include stable angina, unstable angina, and myocardial infarction.

<span class="mw-page-title-main">Angioplasty</span> Procedure to widen narrow arteries or veins

Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty (PTA), is a minimally invasive endovascular procedure used to widen narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis.

<span class="mw-page-title-main">Coronary artery bypass surgery</span> Surgical procedure to restore normal blood flow to an obstructed coronary artery

Coronary artery bypass surgery, also known as coronary artery bypass graft, is a surgical procedure to treat coronary artery disease (CAD), the buildup of plaques in the arteries of the heart. It can relieve chest pain caused by CAD, slow the progression of CAD, and increase life expectancy. It aims to bypass narrowings in heart arteries by using arteries or veins harvested from other parts of the body, thus restoring adequate blood supply to the previously ischemic heart.

<span class="mw-page-title-main">Angiography</span> Medical imaging technique

Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is performed by injecting a radio-opaque contrast agent into the blood vessel and imaging using X-ray based techniques such as fluoroscopy.

<span class="mw-page-title-main">Interventional radiology</span> Medical subspecialty

Interventional radiology (IR) is a medical specialty 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.

<span class="mw-page-title-main">Ischemia</span> Restriction in blood supply to tissues

Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism. Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue i.e. hypoxia and microvascular dysfunction. It also implies local hypoxia in a part of a body resulting from constriction.

<span class="mw-page-title-main">Aortoiliac occlusive disease</span> Medical condition

In medicine, aortoiliac occlusive disease is a form of central artery disease involving the blockage of the abdominal aorta as it transitions into the common iliac arteries.

<span class="mw-page-title-main">Cardiac catheterization</span> Insertion of a catheter into a chamber or vessel of the heart

Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.

<span class="mw-page-title-main">Carotid endarterectomy</span> Surgical procedure

Carotid endarterectomy is a surgical procedure used to reduce the risk of stroke from carotid artery stenosis. In endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms and thickens the inner layer of the artery, or intima, hence the name of the procedure which simply means removal of part of the internal layers of the artery.

<span class="mw-page-title-main">Carotid artery stenosis</span> Medical condition

Carotid artery stenosis is a narrowing or constriction of any part of the carotid arteries, usually caused by atherosclerosis.

The intra-aortic balloon pump (IABP) is a mechanical device that increases myocardial oxygen perfusion and indirectly increases cardiac output through afterload reduction. It consists of a cylindrical polyurethane balloon that sits in the aorta, approximately 2 centimeters (0.79 in) from the left subclavian artery. The balloon inflates and deflates via counter pulsation, meaning it actively deflates in systole and inflates in diastole. Systolic deflation decreases afterload through a vacuum effect and indirectly increases forward flow from the heart. Diastolic inflation increases blood flow to the coronary arteries via retrograde flow. These actions combine to decrease myocardial oxygen demand and increase myocardial oxygen supply.

<span class="mw-page-title-main">Subclavian steal syndrome</span> Medical condition

Subclavian steal syndrome (SSS), also called subclavian steal steno-occlusive disease, is a constellation of signs and symptoms that arise from retrograde (reversed) blood flow in the vertebral artery or the internal thoracic artery, due to a proximal stenosis (narrowing) and/or occlusion of the subclavian artery. This flow reversal is called the subclavian steal or subclavian steal phenomenon, regardless of signs/symptoms being present. The arm may be supplied by blood flowing in a retrograde direction down the vertebral artery at the expense of the vertebrobasilar circulation. It is more severe than typical vertebrobasilar insufficiency.

<span class="mw-page-title-main">Endovascular aneurysm repair</span> Surgery used to treat abdominal aortic aneurysm

Endovascular aneurysm repair (EVAR) is a type of minimally-invasive endovascular surgery used to treat pathology of the aorta, most commonly an abdominal aortic aneurysm (AAA). When used to treat thoracic aortic disease, the procedure is then specifically termed TEVAR for "thoracic endovascular aortic/aneurysm repair." EVAR involves the placement of an expandable stent graft within the aorta to treat aortic disease without operating directly on the aorta. In 2003, EVAR surpassed open aortic surgery as the most common technique for repair of AAA, and in 2010, EVAR accounted for 78% of all intact AAA repair in the United States.

The following outline is provided as an overview of and topical guide to cardiology, the branch of medicine dealing with disorders of the human heart. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in cardiology are called cardiologists.

<span class="mw-page-title-main">Coronary ischemia</span> Medical condition

Coronary ischemia, myocardial ischemia, or cardiac ischemia, is a medical term for abnormally reduced blood flow in the coronary circulation through the coronary arteries. Coronary ischemia is linked to heart disease, and heart attacks. Coronary arteries deliver oxygen-rich blood to the heart muscle. Reduced blood flow to the heart associated with coronary ischemia can result in inadequate oxygen supply to the heart muscle. When oxygen supply to the heart is unable to keep up with oxygen demand from the muscle, the result is the characteristic symptoms of coronary ischemia, the most common of which is chest pain. Chest pain due to coronary ischemia commonly radiates to the arm or neck. Certain individuals such as women, diabetics, and the elderly may present with more varied symptoms. If blood flow through the coronary arteries is stopped completely, cardiac muscle cells may die, known as a myocardial infarction, or heart attack.

Vessel harvesting is a surgical technique that may be used in conjunction with a coronary artery bypass graft (CABG). For patients with coronary artery disease, a vascular bypass may be recommended to reroute blood around blocked arteries to restore and improve blood flow and oxygen to the heart. To create the bypass graft, a surgeon will remove or "harvest" healthy blood vessels from another part of the body, either arteries from an arm or the chest, or veins from a leg. This vessel becomes a graft, with one end attaching to a blood source above and the other end below the blocked area, creating a "conduit" channel or new blood flow connection across the heart.

<span class="mw-page-title-main">Hybrid cardiac surgery</span>

A hybrid cardiac surgical procedure in a narrow sense is defined as a procedure that combines a conventional, more invasive surgical part with an interventional part, using some sort of catheter-based procedure guided by fluoroscopy imaging in a hybrid operating room (OR) without interruption. The hybrid technique has a reduced risk of surgical complications and has shown decreased recovery time. It can be used to treat numerous heart diseases and conditions and with the increasing complexity of each case, the hybrid surgical technique is becoming more common.

Blood vessel disorder generally refers to the narrowing, hardening or enlargement of arteries and veins. It is often due to the build-up of fatty deposits in the lumen of blood vessels or infection of the vessel wall. This can occur in various locations such as coronary blood vessels, peripheral arteries and veins. The narrowed arteries would block the blood supply to different organs and tissues. In severe conditions, it may develop into more critical health problems like myocardial infarction, stroke or heart failure, which are some of the major reasons of death.

<span class="mw-page-title-main">Femoropopliteal bypass</span> Leg artery surgical procedure

Popliteal bypass surgery, more commonly known as femoropopliteal bypass or more generally as lower extremity bypass surgery, is a surgical procedure used to treat diseased leg arteries above or below the knee. It is used as a medical intervention to salvage limbs that are at risk of amputation and to improve walking ability in people with severe intermittent claudication and ischemic rest pain.

<span class="mw-page-title-main">Arterial occlusion</span>

Arterial occlusion is a condition involving partial or complete blockage of blood flow through an artery. Arteries are blood vessels that carry oxygenated blood to body tissues. An occlusion of arteries disrupts oxygen and blood supply to tissues, leading to ischemia. Depending on the extent of ischemia, symptoms of arterial occlusion range from simple soreness and pain that can be relieved with rest, to a lack of sensation or paralysis that could require amputation.

References

  1. "What Is Coronary Artery Bypass Grafting". www.nhlbi.nih.gov. National Institutes of Health — National Heart, Lung, and Blood Institute. Retrieved 11 November 2016.
  2. "Bypass Surgery, Coronary Artery" . Retrieved 8 April 2010.
  3. Zia, A.W., Liu, R. & Wu, X. Structural design and mechanical performance of composite vascular grafts. Bio-des. Manuf. (2022). https://doi.org/10.1007/s42242-022-00201-7
  4. Aboyans, V.; Lacroix, P.; Criqui, M.H. (Sep–Oct 2007). "Large and Small Vessel Atherosclerosis: Similarities and Differences". Progress in Cardiovascular Diseases. 50 (2): 112–125. doi:10.1016/j.pcad.2007.04.001. PMID   17765473.
  5. "What is Cerebral Bypass Surgery?". mayvfieldclinic.com. Mayfield Brain and Spine. Retrieved 8 April 2010.
  6. "Direct Revascularization". Stanford Healthcare. Stanford Medicine. Retrieved 17 November 2023.
  7. Barnett, HJM; The EC/IC bypass study group (1985). "Failure of extracranial-intracranial arterial bypass to reduce the risk of ischemic stroke. Results of an international randomized trial". New England Journal of Medicine. 313 (19): 1191-1200. doi:10.1056/NEJM198511073131904. PMID   2865674.
  8. "Indirect Revascularization". Stanford Healthcare. Stanford Medicine. Retrieved 17 November 2023.
  9. "What Are the Risks of Coronary Artery Bypass Grafting?". nhlbi.nih.gov. National Institutes of Health — National Heart, Lung, and Blood Institute. Retrieved 11 November 2016.
  10. 1 2 3 4 5 "What To Expect After Coronary Artery Bypass Grafting". nhlbi.nih.gov. National Institutes of Health — National Heart, Lung, and Blood Institute. Retrieved 11 November 2016.
  11. "Life After Bypass Surgery" . Retrieved 8 April 2010.
  12. "Heart Bypass Surgery" . Retrieved 8 April 2010.