Vascular bypass

Vascular bypass
Vascular bypass
Other names	Vascular graft
Specialty	Vascular surgery, Cardiac surgery
	[ edit on Wikidata]

Last updated May 31, 2023

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.

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:

"fem-fem" - femoral to femoral bypass, e.g. from right to left. Used when there is no inflow to one femoral artery (i.e., the iliac artery on the receiving side is diseased) but there is aortic flow.
"aorto-bifem" - aortic to both femoral arteries. Used when there is disease at the aortic bifurcation, known as Leriche syndrome, or in both iliac arteries.
"ax-bifem" - axillary artery to both femoral artery bypass. Either axillary artery can be used as the origin of the bypass. Used when patient cannot tolerate a more invasive and higher risk aorto-bifem, or when removing an infected aortic graft such as an EVAR device.
"fem-tib" - femoral to one of the three tibial arteries (Anterior, Posterior or Peroneal). Used for disease of the femoral and tibial arteries, this procedure is used most frequently in people with diabetes, which tends to create disease in the tibial arteries rather than the more proximal arteries.^[4]
a "DP" bypass - any vascular bypass where the target is the dorsalis pedis artery on the dorsum of the foot. It is used in similar situations to those described for the fem-tib bypass.

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.

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]

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.

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.

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.

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.

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.

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.^[6]

Risks of the bypass:

Acute graft occlusion is the occlusion (blockage) of a vascular bypass graft shortly after the bypass is performed. Its causes, which are distinct from those of chronic graft occlusion, include technical failure (e.g. anastomotic stricture, incomplete valve lysis in non-reversed vein) and thrombosis. It is rare, but almost always requires reoperation.

General risks of surgery:

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.^[7]

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.^[7]

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.^[7]^[8]

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.^[7]

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.^[7]^[9]

Related Research Articles

<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. A deflated balloon attached to a catheter is passed over a guide-wire into the narrowed vessel and then inflated to a fixed size. The balloon forces expansion of the blood vessel and the surrounding muscular wall, allowing an improved blood flow. A stent may be inserted at the time of ballooning to ensure the vessel remains open, and the balloon is then deflated and withdrawn. Angioplasty has come to include all manner of vascular interventions that are typically performed percutaneously.

Arteriosclerosis is the thickening, hardening, and loss of elasticity of the walls of arteries. This process gradually restricts the blood flow to one's organs and tissues and can lead to severe health risks brought on by atherosclerosis, which is a specific form of arteriosclerosis caused by the buildup of fatty plaques, cholesterol, and some other substances in and on the artery walls. It can be brought on by smoking, a bad diet, or many genetic factors.

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.

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.

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.

Peripheral artery disease (PAD) is an abnormal narrowing of arteries other than those that supply the heart or brain. PAD can happen in any blood vessel, but it is more common in the legs than the arms.

<span class="mw-page-title-main">Vascular surgery</span> Medical specialty, operative procedures for the treatment of vascular disorders

Vascular surgery is a surgical subspecialty in which vascular diseases involving the arteries, veins, or lymphatic vessels, are managed by medical therapy, minimally-invasive catheter procedures and surgical reconstruction. The specialty evolved from general and cardiovascular surgery where it refined the management of just the vessels, no longer treating the heart or other organs. Modern vascular surgery includes open surgery techniques, endovascular techniques and medical management of vascular diseases - unlike the parent specialities. The vascular surgeon is trained in the diagnosis and management of diseases affecting all parts of the vascular system excluding the coronaries and intracranial vasculature. Vascular surgeons also are called to assist other physicians to carry out surgery near vessels, or to salvage vascular injuries that include hemorrhage control, dissection, occlusion or simply for safe exposure of vascular structures.

Restenosis is the recurrence of stenosis, a narrowing of a blood vessel, leading to restricted blood flow. Restenosis usually pertains to an artery or other large blood vessel that has become narrowed, received treatment to clear the blockage and subsequently become renarrowed. This is usually restenosis of an artery, or other blood vessel, or possibly a vessel within an organ.

A pseudoaneurysm, also known as a false aneurysm, is a locally-contained hematoma outside an artery or the heart due to damage to the vessel wall. The injury passes through all three layers of the arterial wall, causing a leak, which is contained by a new, weak, "wall" formed by the products of the clotting cascade. A pseudoaneurysm does not contain any layer of the vessel wall.

<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.

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.

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.

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.

Coronary ischemia, myocardial ischemia, or cardiac ischemia, is a medical term for a 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.

Endoscopic vessel harvesting (EVH) is a surgical technique that may be used in conjunction with coronary artery bypass surgery. For patients with coronary artery disease, a physician may recommend a bypass 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, often from the patient's leg or arm. 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.

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.

References

↑ "What Is Coronary Artery Bypass Grafting". www.nhlbi.nih.gov. National Institutes of Health — National Heart, Lung, and Blood Institute. Retrieved 11 November 2016.
↑ "Bypass Surgery, Coronary Artery" . Retrieved 8 April 2010.
↑ 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
↑ 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.
↑ "What is Cerebral Bypass Surgery?". mayvfieldclinic.com. Mayfield Brain and Spine. Retrieved 8 April 2010.
↑ "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.
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.
↑ "Life After Bypass Surgery" . Retrieved 8 April 2010.
↑ "Heart Bypass Surgery" . Retrieved 8 April 2010.

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[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.

[AHA-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.

[MayField-5] "What is Cerebral Bypass Surgery?". mayvfieldclinic.com. Mayfield Brain and Spine. Retrieved 8 April 2010.

[6] "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.

[NIHafter-7] 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.

[ehealth-8] "Life After Bypass Surgery" . Retrieved 8 April 2010.

[9] "Heart Bypass Surgery" . Retrieved 8 April 2010.

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