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 donÕt 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 ÒevidentialÓ. 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 ÔActuaryÕ) 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 ÒopinionÓ. 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 ParkinsonÕs Disease or Multiple Sclerosis (both
conditions) - that requires cessation of employment. Pension through ill health.
Point (f) is a
burden to ÒseekÓ 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 ÔplayedÕ.
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. ItÕs 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?