lecture 7 - aortic and pericardial disease Flashcards
Aortic Dissection: Introduction
Epidemiology
Rare – incidence in the UK is 3-4 per 100,000 person-years • Mean age at presentation 63 years • M:F = 2:1
Aortic Dissection: Introduction Pathophysiology
- Disruption of the middle layer (tunica media) of the wall of the aorta due to bleeding within it
- Initial tear in the inner layer (tunica intima) found in 90% of cases
- False lumen can extend for a variable distance in either direction, typically anterograde
- Blood in false lumen can track through the intimal flap back into the true lumen or through the tunica adventitia
Aortic Dissection: Clinical Classification Aortic Dissection: Risk Factors
Along with the DeBakey classification, the Stanford classification is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management. The Stanford classification divides dissections into:
type A: A affects ascending aorta and arch
accounts for ~60% of aortic dissections
surgical management
may result in:
coronary artery occlusion
aortic incompetence
rupture into pericardial sac with resulting cardiac tamponade
type B: B begins beyond brachiocephalic vessels
accounts for ~40% of aortic dissections
dissection commences distal to the left sub-clavian artery
medical management with blood pressure control
Along with the Stanford classification, the DeBakey classification is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management. The DeBakey classification divides dissections into:
type I: involves ascending and descending aorta (=Stanford A) type II: involves ascending aorta only (=Stanford A) type III: involves descending aorta only (=Stanford B)
Aortic Dissection: Clinical Classification Aortic Dissection: Risk Factors
Increased aortic wall stress • Hypertension – present in 72% of patients (IRAD) • Cocaine (and other stimulant) use • Direct trauma, including coronary intervention • Deceleration or torsional injury • Weight lifting • Coarctation of the aorta
Aortic media abnormalities • Genetic – Marfan syndrome, Ehlers-Danlos syndrome, Turner syndrome, bicuspid aortic valve disease • Vasculitis – giant cell arteritis, Takayasu arteritis, rheumatoid arthritis, syphilitic aortitis • Other – pregnancy, polycystic kidney disease, infections involving aortic wall
Aortic Dissection: Symptoms
• Typically severe “tearing” pain in chest and/or back: – usually retrosternal (anterior) with type A and inter-scapular (posterior) with type B dissection – abrupt onset and maximal at onset – may migrate as dissection progresses – may disappear – can radiate anywhere
• May be associated with
symptoms of complications
Aortic Dissection Signs
• Pulse deficit, including – radio-radial delay – different BP readings in both arms • May be associated with signs of complications
Aortic Dissection: Complications
Cardiac
• Acute aortic regurgitation
• Myocardial ischaemia or infarction (usually RCA infarct)
• Pericardial effusion (haemopericardium) ± tamponade
• Heart failure
• Syncope
Others
• Ischaemic stroke, acute paraplegia
• Pleural effusion, aortopulmonary fistula
• Mesenteric ischaemia, gastrointestinal haemorrhage
• Renal infarction, acute renal failure
• Limb ischaemia
Aortic Dissection: Diagnosis
• Blood tests – not useful for definitive diagnosis
– D-dimer - level less than 500 ng/mL may rule out aortic dissection
(NPV 96%) but use may be limited to low-risk group
– Smooth muscle myosin heavy chain – diagnostic accuracy poorer
than definitive imaging
• Imaging – needed to confirm diagnosis and guide management
– chest x-ray – not diagnostic (Sensitivity of mediastinal widening = 39%)
– TTE – inferior accuracy compared to other imaging
– TOE
– Spiral CT
– MRI
Aortic Dissection: Definitive Imaging
TOE Bedside Cardiac info, Availability, Operator dependent
(Sedation), 98% sensitive, 95% specific.
Spiral CT - v available but contrast and radiation. - 100% sensitivity, 98% specificity.
MRI - good cardiac info, poor availability, some patients precluded due to contrast,. 98% specific and sensitive.
Aortic Dissection: Treatment General (all patients)
• Manage in high-dependency unit
– cardiac monitoring
– arterial line
– urinary catheter
• Analgesia
– e.g. IV morphine
• BP control
– IV beta blocker, IV calcium antagonist or IV sodium nitroprusside
– Aim for systolic BP 100-120 mmHg or lowest possible for end-organ perfusion
Aortic Dissection: Treatment Definitive (type A dissection)
• Surgical emergency
• Mortality increases by 1-2% per hour after onset of symptoms without
surgery
• Surgery involves excision of intimal tear, obliteration of entry into false
lumen proximally and reconstruction of aorta with synthetic graft
• Operative mortality 7-36% depending on centre
Aortic Dissection: Treatment Definitive (type B dissection)
• Medical therapy (i.e. tight BP control and serial imaging)
• Consider surgery or endovascular stenting if:
– complicated course, e.g. occlusion of major aortic branch with
critical end-organ ischaemia
– ongoing extension of dissection (ongoing pain)
– aneurysmal expansion
– Marfan syndrome
Aortic Dissection: Prognosis
• In-hospital mortality 27.4%
• Type A dissection
– mortality 40% in first 24 hours without surgery
– survival at 1 year after surgery 96%
• Type B dissection
– survival at 1 year on medical therapy 85%
IRAD
describe the pericardium
• The pericardium is a double layered fibroserous sac that envelops the heart • Inner serosal layer is called visceral pericardium (or epicardium) • Outer fibroserous layer is called parietal pericardium and divided into: – outer fibrous layer – inner serous layer with microvillous surface specialised for secretion of pericardial fluid • Pericardial cavity normally contains 15- 25 ml of pericardial fluid • Blood supply comes from internal mammary arteries
what is pericarditis
- = inflammation of the pericardium
* can occur with or without pericardial effusion
