Aorta Surgery

 

General           

 

Disorders in the chest will often manifest with abdominal symptoms. It is always wise to examine the chest when evaluating any abdominal complaint. An aneurysm is a localised dilation of a blood vessel, particularly the aorta or a peripheral artery. Aortic aneurysms can develop anywhere along the length of the aorta but 75% are located in the abdominal aorta. Saccular aneurysms represent localised out pocketings of the aortic wall, whereas fusiform aneurysms are characterised by a circumferential widening of the aorta. Most aortic aneurysms are fusiform. The most common cause of aneurysm is arteriosclerosis, which may weaken the aortic wall causing it to expand. The treatment of fusiform aneurysms differs from saccular aneurysms (more common in the brain - reverse of aortic aneurysms) as it is not always possible to clip a fusiform one. It is really just a dilation of the normal vessel rather that a balloon-like structure off the side of a normal vessel. Closure of the main or parent vessel is an accepted form of treatment for many aneurysms.

 

Hypertension and cigarette smoking contribute to the degenerative process, and there is a familial occurrence of abdominal aortic aneurysms. Trauma, arteritis syndromes, syphilis and congenital connective tissue disorders (eg Marfan's syndrome) can all lead to the formation of aneurysm. Tertiary syphilis tends to affect particularly the ascending aorta. Tertiary syphilis typically causes aneurysms of the aortic root and ascending aorta. Aortic insufficiency and inflammatory stenosis of the coronary artery ostia are common symptoms following upon this condition (sequelae).

 

Traumatic aneurysms

 

Traumatic aneurysms most frequently follow blunt chest trauma and are typically located at the  descending thoracic aorta at the point where it becomes fixed to the posterior thoracic cage. Such aneurysms are false aneurysms - contain haematomas that have developed from blood leaked through the traumatically torn aorta wall. These severe blunt chest injuries should be excised. Very often unless in an emergency (no symptoms in many cases but if diagnosed) may not be operated on because the risk/benefit to patient is unfavourable. The aneurysm can be left for some time - measured in years. The growth rate is about 5% size/year).

 

Abdominal aortic aneurysms

 

Around 90% of abdominal aortic aneurysms begin below the renal arteries, commonly extending distally into either or both of the iliac arteries. Abdominal aortic aneurysms may cause pain (lumbosacral region). Pain usually steady with abdominal pulsation. These often become huge and may even rupture without any antecedent symptoms. Palpation often reveals the abnormally wide abdominal aorta. But even large aneurysms may be difficult to detect. Rapidly enlarging aneurysms with imminent rupture are frequently tender.

 

Natural history of abdominal aortic aneurysms is closely related to size. Rupture is uncommon when they are less than 5cm wide but more so if greater than 6cm wide. Elective surgery is recommended for all those >6cm unless there is a major medical contraindication to surgery. Elective surgery is also generally recommended for aneurysms 4-6cm for good surgical risks - suitable candidates with the mortality rate at 2%.

 

Surgical repair

 

The excision (complete removal) of the aneurysm and its replacement with a synthetic conduit (synthetic graft) may have to be carried into either or both iliac arteries if the aneurysm involves them. Extension of the aneurysm above renal arteries necessitates their re-implantation onto the synthetic graft. Many patients have generalised arteriosclerosis, so cardiovascular status should be assessed before surgery. High-risk cardiac patients might need coronary artery (see Coronary Artery Bypass Graft - CABG) problems attended to before any surgery for an aneurysm.

 

The rupture of an abdominal aneurysm is highly lethal usually preceded by excruciating pain in lower abdomen and back with tenderness of the aneurysm. Depending on severity of bleeding, hypovolemic (low volume) shock and death may rapidly follow. Rupture or threatened rupture of abdominal aneurysm is a surgical emergency. Operative risk for rupture is about 50%.

 

Thoracic aortic aneurysms - includes those that extend from descending thoracic aorta into the upper abdomen (thoracoabdominal aneurysms). This accounts for 25% of all aortic aneurysms. The enlarging aorta result in symptoms relating to pressure against, or erosion of, adjacent structures. Pain is common especially in the back where the aorta contacts the spine or the thoracic cage. Common symptoms are cough, wheezing, haemoptysis (expectoration of blood) from tracheal or bronchial compression or erosion, dysphagia (swallowing difficulties) from oesophageal compression, or hoarseness from compression of left recurrent laryngeal nerve. Horner's syndrome is a combination of small pupils (miiosis), sunken eye (erophthalmos) and drooping upper eyelid (phosis), due to paralysis of sympathetic nerve in the region of the neck. This and abnormal chest wall pulsations may be signs of thoracic aneurysms. However, as with abdominal aortic aneurysms, thoracic aneurysms may become huge while remaining asymptomatic.

 

One particularly common form of thoracic aneurysm involves widening of the proximal aorta and the aortic root, causing aortic insufficiency (annuloaortic ectosia). About 50% of patients have Marfan's syndrome (a connective tissue disorder) which affects heart valves and aortic tissue and has various skeletal abnormalities including long finger, arachnodactyly - extreme length of fingers and toes, high-arched palate and dislocation of lens.

 

Thoracic aneurysm should be resected if >=7cm. But elective surgical repair is recommended for aneurysms >=6cm in patients with Marfan's syndrome which are more prone to rupture. Repair consists of resection and replacement with a synthetic conduit. A particular satisfactory result is the Bentall repair - the use of a composite graft. Involved with proximal aorta and aortic annulus (especially if complicating aortic insufficiency). See Port-Access. This consists of resection of the dilated ascending aorta down to aortic annulus (or ring of blood vessels that surrounds the valve), with excision of the coronary arteries around a button of aortic wall. A composite graft (synthetic conduit into which a prosthetic aortic valve has been inserted at one end) is then sewn into place between the transected aorta distally and the aortic annulus proximally. The coronary arteries are then re-implanted into the graft. Recently, some surgeons have been using a homograft of the proximal aorta and aorta valve instead of synthetic materials. Mortality for elective repair of thoracic aneurysms is 10 - 15%, although risk increases significantly in complicated aneurysms - involvement of aortic arch or thoracoabdominal aorta.

 

Aneurysms are often asymptomatic. Often they are detected on chest X-ray as a mass. Computer Tomography (CT) or Magnetic Resonance Imaging (MRI) scan is used to detect the exact location and size. If rapid growing, pressure can be put on the surrounding structures in the chest causing pain. Aneurysms can be located in the aortic root or the ascending aorta near the aortic valve. They frequently also involve the aortic valve. The damaged section of blood vessel extends down to the annulus or ring of the blood vessel that surrounds the valve. Once the annulus is weakened, the valve cannot maintain tight seal and valve becomes incompetent or regurgitant - it leaks. Aneurysms in this location are referred to as having Annuloaortic Ectosia.

 

Peripheral arterial aneurysms

 

These can arise in any of the aortic branches usually as a result of arteriosclerosis. Trauma, arteritis and infections (mycotic aneurysm) are less frequent causes. The popliteal arteries (behind the knee) are the most common peripheral arterial aneurysms. They are mostly bilateral (70%) and are frequently associated with abdominal aortic aneurysms (particularly when bilateral). They rarely rupture but may serve as a focus for abrupt thrombotic occlusion of the involved popliteal artery, jeopardising the foot on the affected side. A thrombus within the aneurysm may lead to distal embolism. Arteriography is used to establish diagnosis and assess the circulation distal to the aneurysm. A surgical resection with graft replacement of excised segment is advisable.

 

Aneurysms of the iliac and femoral arteries are less frequent but should be excised when detected. An upper extremity aneurysm is rare. The subclavian artery is sometimes associated with cervical ribs and may diminish in size if this rib is removed, although the aneurysm may require primary resection. Splanchnic (inward, visceral) artery aneurysms are also infrequent. The most common is the splenic artery. Less common sites are the hepatic and superior mesenteric arteries. None of these are usually diagnosed until rupture. They should be repaired if symptomatic but asymptomatic repair is based on age, surgical risks, size and location. Mycotic aneurysms occur at sites of localised bacterial or fungal infections in aortic or arterial walls. They are usually the result of metastatic infection from septicaemia - most common cause of which is infectious endocarditis. Infection may spread to blood vessel walls from contiguous sepsis or trauma.

 

Mycotic aneurysms of cerebral arteries are particularly hazardous complications of infectious endocarditis, often resulting in intracranial haemorrhages. Surgery is the only cure for an aortic aneurysm. But timing is based on relative risk of surgery vs relative risk of rupture. Rupture will occur when weakened wall of blood vessel finally tears, much as a stretched-out elastic band will finally snap under pressure. The risk of rupture is determined by the location and size of the aneurysm (>6cm diameter considered surgical candidates) and rate of recent growth of the aneurysm since onset of symptoms (chest pain) associated with aneurysm. If surgery is not yet deemed necessary, then a medically treated combination of diet, exercise and medication is used to reduce blood pressure. This is aimed at preventing further weakening while avoiding inherent risk of surgery. Surgery may be required if not responding to medical management.

 

Types of Aortic Aneurysms Aneurysms of Ascending Aorta

 

Most common type. Low risk associated with repair of these aneurysms (around 2% mortality rate) and high probability of eventual rupture makes elective surgery recommended. Procedure involves replacement of the damaged section with Dacron tube graft. In cases where aortic valve is also damaged, surgeon uses a combination Dacron tube graft and valve replacement. Operation commonly referred to as a Bentall-DeBono procedure (after the two pioneering surgeons).

 

Aneurysms of the Aortic Arch

 

This requires temporary suspension of cardiopulmonary bypass, process known as circulatory arrest. This is required to replace section of aorta attached to the brachiocephalic (innominate) artery - the left common carotid artery and the left subclavian artery. Damage to the aortic arch is usually accompanied by damage to the ascending aorta. Repair both sections with a single Dacron graft.

 

Aneurysms of the Descending Aorta

 

When aneurysm located in the descending aorta, radically different operative approach is required. Whenever possible a medical, non-operative approach is preferred for patients with small aneurysms in the descending aorta. If surgery is required, the incision is made in the left side and may be extended into the diaphragm and abdomen. Cardiopulmonary bypass is usually only required to support the lower half of the body The damaged section of the aorta is then replaced with a Dacron tube graft. The replacement can extend into sections of the abdominal aorta. This procedure is only performed with patients for whom medical treatment has failed and the aneurysm has enlarged, as there is a risk of spinal cord injury - the blood supply to the spinal cord stems from the descending aorta.

 

Aneurysms of the Ascending Aorta, the Aortic Arch and the Descending Aorta

 

In some patients the entire length of the aorta - both ascending and descending - is enlarged and requires surgical repair. Rare condition. For such individuals two separate operations are performed and is referred to as the "Elephant Trunk Procedure". The name comes from the trunk-like nature of the Dacron graft. The first on the ascending aorta and the aortic root and the second on the descending aorta. The first operation is on the ascending aorta and aortic arch and initially follows the standard operative procedure. Repair is effected to the ascending aorta followed by repair to the aortic arch. In many patients the damage to the ascending aorta extends into the aortic annulus or the ring surrounding the aortic valve. The aortic valve is replaced at the same time as the ascending aorta (Dacron tube graft with valve attachment). A cardio-pulmonary bypass (heart-lung machine) is used. This is responsible for both oxygenating the blood and maintaining blood pressure.

 

The surgeon enters the chest through a median sternotomy incision which opens the full length of the breastbone. The heart is stopped and the patient remains in a hypothermic state throughout the operation. Major aortic surgery requires a special version of cardiopulmonary bypass. In standard bypass the blood is diverted to the heart-lung machine through cannulae (or tubes) placed in the aorta and other major blood vessels.

 

In aortic surgery the blood flow is diverted through cannulae placed in the femoral artery of the leg instead of the aorta. This special arrangement permits the operation on the aorta while blood flow is diverted to the heart-lung machine, sustaining circulation throughout the body.

 

Abdominal aortic aneurysm

 

Mostly the three fold increase in last 40 years due to upsurge in smoking since WWII. More people live longer so occurs more frequently. In America about 15,000 die each year as a result of ruptured abdominal aortic aneurysm compared to the 500,000 who die of heart attack. Relatively small numbers (3%). An abdominal aneurysm may rupture and cause sudden death but if detected early this silent danger can be eliminated by surgery in 95% of cases. The aneurysm is a bulging or ballooning of an artery wall. Usually occurs when arterial wall becomes weak or damaged by accumulation of cholesterol-containing fatty deposits (atherosclerosis).

 

Contributing factors include high blood pressure, smoking, male gender, age 55 or older, family history of abdominal aortic aneurysm. Once elasticity is reduced force of heartbeat can cause artery to slowly stretch and bulge. As with any aneurysm the danger is that the abdominal aortic aneurysm will leak or burst, causing life-threatening bleeding. The aorta is the largest artery in the body. An aneurysm usually develops beyond where the aorta branches to kidneys and above where it divides to supply blood to pelvis and legs. Normal diameter is within range of 3/4" to 1" (2 - 2.5cm). Small aneurysms (less than 2" = 5cm) rarely rupture. As they grow bigger than this the risk of rupture increases by 5% each year. They mostly enlarge silently causing no obvious problem - maybe pain in the back but mostly asymptomatic.

 

Careful examination can detect 70 - 80% of these - the sounds of turbulent blood flow over aorta's roughened surface. Palpation can determine if pulsating mass. Overweight reduces accuracy so ultrasound may be used. CT is also used but MRI not cost effective. Surgery almost always when diameter more than 2" (5cm). Incision into abdomen to open up aorta and remove cholesterol and fatty build-up. Surgeon implants a flexible tube (graft) to replace the enlarged artery. Recovery from elective surgery takes about 6 weeks (includes one week in hospital). Emergency repair of a ruptured aortic aneurysm is less successful - 62% die before reaching hospital. Of those who don’t die only 50% survive surgery (50 x 38 = 19% survivors overall).

 

As an alternative to abdominal surgery new procedure called endovascular surgery developed. Involves a collapsed graft passed up the femoral artery in leg into weakened aorta. Graft is secured by metallic stents - similar to balloon angioplasty. Graft is inflated to restore normal blood flow - graft takes pressure off outer aorta wall. This endovascular surgery may become safer and easier alternative to traditional surgery - especially for people at high surgical risk. Prevention and early detection are keys to avoiding death from an abdominal aortic aneurysm. A vasospasm is a contraction of the arteries in the brain that occurs after an aneurysm ruptures. It is believed to be a response to leakage of blood. If severe, this condition can result in a stroke even if patient has had the aneurysm successfully treated (aorta surgery and stroke claim? Interesting situation). Although vasospasm occurs in many patients there are many methods used for prevention and treatment. Initial method is to administer fluids through an intravenous catheter. Any vein but usually jugular in neck.

 

Medications like calcium channel blockers are helpful. Increased blood pressure can help if other measures do not improve the condition. Angiogram can be used to direct catheter into narrowed vessel to enlarge its diameter with special medication or mechanically with a balloon. Some case reports suggest patients with heart disease the use of intra aortic balloon counterpulsion devices may improve flow through the narrowed cerebral vessels. Most aneurysms (even non ruptured) should be considered for treatment. Some discovered because of pressure on surrounding nerves. For brain aneurysm (behind eye) if CT or MRI detected it in the first place then a formal cerebral angiogram would be next step. This is study of blood vessels in brain.

 

An arteriovenous malformation (AVM) is an abnormal association of arteries and veins which has less resistance than normal capillaries. More blood flows through such vessels and are more likely to develop an aneurysm. This can be an aneurysm on a vessel leading to the AVM or a vessel within the AVM. Either increases risk of haemorrhage but can be eliminated with proper treatment.

 

Aneurysms of the Brain

 

Congenital saccular aneurysms of the intracranial arteries and particularly the "Circle of Willis" (berry aneurysms) may occur in isolation or association with other congenital anomalies (coarctation - narrowing or constriction of aortic arch causing hypertension in upper part of body) or polycystic kidneys. The "Circle of Willis" is a confluence of the major arterial channels supplying brain and is located in the base of brain. Since most aneurysms arise at branch points on the vessels this area is the common location in which to discover an aneurysm (branch points considered weak points - most likely location). A non-ruptured aneurysm in the brain carries between a 1- 3% per year risk of rupture. This is relatively low so no true "urgency" for surgical treatment of non-ruptured aneurysms unless they demonstrate enlargement (headaches, pressure on surrounding nerves giving rise to neurological deficits. It is best to obtain an angiogram.

 

Aneurysms of the brain are shown to be inherited in certain families. Usually a strong family history of several relatives suffering a subarachnoid haemorrhage or being discovered to harbour an aneurysm. Those with disorders of the kidneys or connective tissues (Marfan's syndrome) may be at higher risk for aneurysm development. Non-ruptured aneurysms may also be detected if they are associated with "warning leak" headache. Not truly non-ruptured but rupture is so small as to produce only a slight leakage of blood which results in minor headache.

 

Intracranial aneurysm is an abnormal increase in diameter (dilation) of a blood vessel. Occurs in all age groups but steadily increases for the over 25's. Most devastating consequence of intracranial aneurysm which often lead to severe disability or death result from their rupture and bleeding into space around brain. Major rupture often preceded by "warning leak" as a new or uncharacteristic headache. May also be detected prior to rupture due to pressure on surrounding nerves. Treatment before a catastrophic haemorrhage is much better than those treated after so need for adequate evaluation of patient suspected of harbouring an intracranial aneurysm is of paramount importance.

 

Non-ruptured intracranial aneurysms can be detected by non-invasive techniques such as MRI, CT and MRA (magnetic resonance angiography) or lumbar puncture. Formal cerebral angiography carried out if suspected. Microsurgical (microvascular) clipping as surgical procedure remains cornerstone of therapy for intracranial aneurysms. This is placing a clip around the neck of the aneurysm during an open operation. A less invasive technique which does not require an operation is neuroendovascular therapy. This uses microcatheters to deliver coils to the site of the enlarged blood vessel that occludes (closes up) the aneurysm from inside the blood vessel. Patients with a ruptured intracranial aneurysm should be treated as soon as possible, regardless of the securing method.

 

Insurance perspective

 

Disease of aorta is corrected by excision and surgical replacement with a graft. Thoracic and abdominal aorta is included in its isolation but not branches. Traumatic injury is excluded. How is traumatic injury defined? Could such an injury result in aortic disease though not directly injure the aorta itself? Weaken it and make it susceptible to rupture? A crash - chest impact injury? Rupture of aorta in contact with spine or thoracic cage?

 

Congenital heart defect. Such defects may not come to light until adulthood but perhaps before a condition becomes critical it is corrected. The problem created is simply that the non-critical condition isn't covered but if this develops into a critical condition (may or may not become critical if corrected) then such congenital defects are probably used as evidence of a pre-existing condition. See Atrial Septum Defect. No one is asked to confirm any such congenital problems? By definition they probably are not aware of them. This is the effect of no time limit - no fixed moratorium. Like Marfan's diseases - later in life may have an aortic aneurysm as a direct result of this congenital defect. Perhaps the congenital condition is recognised well before any aorta problems but it is a pre-existing condition. The medical history may provide something to interpret as “evidential”. Any claim will fail.

 

This type of surgery is necessary in the treatment of aneurysms. An injury may lead to a weakness that ultimately manifests as an aneurysm. This becomes an emergency but could be an Excluded Cause:

 

(a)     The consequences of intentional self-injury, the taking of alcohol or drugs or participation in any criminal act.

 

(b)     The consequences of war, invasion, act of foreign enemy, hostilities (whether war be declared or not), civil war, rebellion, revolution, insurrection, military or usurped power, or active participation in riot or civil commotion.

 

(c)     Bodily injury sustained while engaging in any pursuit which in the opinion of the Actuary for the time being of the Company (the ‘Actuary’) is hazardous.

 

(d)     Disablement as a result of pregnancy and occurring during pregnancy or within two months thereafter.

 

(e)     Disability after the date the Life Assured would normally retire or have retired but for disability, regardless of when the disability commenced.

 

(f)      The failure of the Assured to seek or follow medical advice.

 

Points (a), (b) and (d) - no comment.

 

Point (c). This allows for an “opinion”. Interestingly, well after my challenge had began the Loss of Hearing condition was revoked. Slipped in unannounced. This involves permanent loss of hearing in BOTH ears. Mine is only partial and in ONE ear only. However, I have engaged in contact sport - but not since diagnosis - so presumably the hearing is implicated in the medical history and so must be an associated symptom (or manifestation).

 

Point (e) does not explicity state age 65 - pensionable age but range can be anything between 55 and 65 yet may still have an active mortgage. Also a disability may be a growing one that originally is a nuisance but transforms into one of serious consequence - examples are Parkinson’s Disease or Multiple Sclerosis (both conditions) - that requires cessation of employment. Pension through ill health.

 

Point (f) is a burden to “seek” advice - and follow it. This would presumably compromise smoking related issues or high blood pressure and concerns regarding weight control if advice was shown to be not followed. The question would be when advice should be sought. This must vary between individuals since a problem for one may not be a problem to another. Nevertheless an interpretation of failure to seek advice might become expedient in the event of a claim. A medical history entry might be construed as suggestive - in hindsight.

 

Be very careful: seeking medical advice may be construed as knowing of a condition. Even suspecting one. Why else would you be seeking it? Perverse? Certainly, but this demonstrates the cynical game being ‘played’.

 

Repair to damage is excluded but what of indirect weakness that results in an aneurysm? The damaged part is excised and a synthetic conduit placed between the two severed parts to effect the join. A graft. If an aneurysm spread into one of the branches in addition to the aorta itself then this would compromise the definition. Result. Claim would fail. Even though a critical condition of aorta? Aorta surgery is a critical illness but not if it spreads into branches. Why is the branching excluded. Is it too complicated? No. It’s the most common.

 

A situation may present whereby a non-critical aneurysm is of the isolated aorta and so does not require immediate surgery - growth rate is slow - but spreads into branches and becomes critical as it grows and spreads. So the transform of a non-critical condition into a critical one cannot be claimed as it develops and so becomes void. So both the non-critical and critical condition cannot be claimed. A traumatic aneurysm obviously would not be covered - by definition of a pre-existing condition. It may be medically prudent to leave alone. Condition requires surgery to be carried out but only after a much earlier diagnosis. An earlier condition that is known about and left for medical considerations will automatically be disqualified when it becomes critical. By definition. Some 90% of abdominal aneurysms begin below the renal arteries, commonly extending distally into either or both of the iliac arteries. This is probably the answer to the exclusions. It is the most common. Unless you know all this then aorta surgery looks good cover - but it isn't.

 

If predisposed to develop aorta aneurysm - will this result in claim problems? Would family history be regarded as non-idiopathic although the cause might not be identified. A familial connection may be sufficient grounds to construe a known reason. The other 50% appear to be idiopathic (absolutely no known reason). Smoking would almost certainly be linked to causative factors. The popliteal arteries (behind knee) are the most common peripheral arterial aneurysms. They are mostly bilateral (70%) and frequently associated with abdominal aortic aneurysms (particularly when bilateral). They rarely rupture but may serve as a focus for abrupt thrombotic occlusion of the involved popliteal artery, jeopardising the foot on the affected side (loss of limb but below/above knee?). If a lower leg limb is to be amputated then usual to be below the knee - if possible - to allow for a prosthesis to be attached. The claim requires above knee so a successful claim means no artificial leg possible. Would not elect to have so much leg removed if unnecessary.

 

Since most aneurysms arise at branch points on the vessels this area is the common location in which to discover an aneurysm. The branch points are considered weak points - the most likely location. Clearly the reason why the aorta and its branches are specifically EXCLUDED.

 

An non-ruptured aneurysm in the brain carries between a 1 - 3% per year risk of rupture. This is relatively low so no true "urgency" for surgical treatment of non-ruptured aneurysms unless they demonstrate enlargement. Headaches, pressure on surrounding nerves giving rise to neurological deficits - associated symptoms to disqualify before diagnosis?

 

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