Pedagogical disambiguation: Emergency Medicine Lecture Notes and Evidence Based emergency medicine principles with regular review and updates.
Acute Pulmonary Oedema or Acute heart failure syndrome (AHFS) spectrum can be divided into 5 groups as regards therapeutic management
- 3 cases per 100 000 people per year; up to 25% missed diagnosis ante-mortem. ‘Typical’ case is 60-80 years old, M>F 3:1, with hypertension. Overall in-hospital mortality 27%.
- Inherited disease (especially younger patients < 40 yrs)
- Marfan’s syndrome (fibrillin gene mutations), Ehlers-Danlos syndrome type IV (collagen defects), Turner syndrome, annulo-aortic ectasia and familial aortic dissection.
- Aortic wall stress
- Hypertension (72%), previous cardiovascular surgery, bicuspid or unicommisural aortic valve, aortic coarctation, iatrogenic, infection (syphilis), arteritis such as Takayasu’s or giant cell, aortic dilatation / aneurysm, wall thinning, ‘crack’ cocaine or Ecstasy (abrupt catecholamine-induced hypertension).
- Reduced resistance aortic wall
- Increasing age, pregnancy + Marfan’s or enlarged aortic root.
European Society of Cardiology. Diagnosis and management of aortic dissection. Eur Heat J 2001;22:1642-81. [PDF Reference]
Clinical Presentation (incidence % and likelihood ratios)
- Severe or ‘worst ever’ (90%), abrupt (84-90%; LR+ 1.6, LR- 0.2), sharp (64%) or tearing (50%) retrosternal or interscapular pain, migrating (16%), down the back (46%), maximal at onset (not crescendo build up, as in an AMI).
- Aortic incompetence (32%), cardiac tamponade, myocardial ischaemia (but only 2-5% of ECG’s mimick AMI + incidence of AMI is 800 x that of aortic dissection!).
- Different BP >20 mmHg in arms, or missing pulse (15-30%; LR+ 5.7).
- Pleural rub or effusion, haemothorax.
- Altered consciousness, syncope (13 %), hemiplegia (5%), paraplegia. Any focal neurology (17%; LR+ 6.6-33).
- Abdominal pain (43% descending, 22% ascending), intestinal ischaemia, bowel infarct.
- Oliguria, haematuria.
- Widened mediastinum (56-63%), abnormal aortic contour (48-71%), aortic knuckle double calcium sign >5mm (9-14%), pleural effusion (L>R; 16%), tracheal shift, left apical cap. ‘Normal’ in 11-16%.
- Limited prospective data suggest D-dimer is useful to risk stratify and ‘rule out’ if negative (< 0.1 µg/mL has NPV 100%; <500 ng/mL NPV 95% / LR- 0.07 in first 24 hours).
- Perhaps consider particularly if access to imaging is limited (i.e. in rural / remote areas).
- Also may help ‘rule-in’ if >1600 ng/mL within the first 6 hours (note: this was only in patients already with a suspected dissection, NOT in all chest pain patients in general).
- Transthoracic 75% diagnostic Type A (ascending), 40% descending (Type B).
- Transoesophageal (TOE). Much higher sensitivity (97-99%) / specificity, though operator-dependent, needs sedation / intubation, and is less available. Useful in ICU / perioperative.
- Helical CT
- Most useful screen for widened mediastinum etc, with sensitivity 83- >98%. Multiplane/slice scanners may even negate additional need for TOE or aortography to plan operative management.
- MRI / MRA
- Excellent sensitivity and specificity, but limited by availability.
- Was the traditional ‘gold standard’, delineating aortic incompetence and branch vessel involvement, but in fact lacks sensitivity.
- Ascending Type A:
- Immediate blood pressure control prior to transfer for operation using IV beta blocker (propranolol, esmolol or labetalol) combined with SNP (or GTN) as vasodilators aiming for SBP 100-120 mmHg, and surgery or endovascular stenting.
- Descending Type B:
- Medical control of BP with beta blockers, with surgery or endovascular stent grafting for selected patients with an unfavourable outlook.
Eggebrecht H et al. Endovascular stent-graft placement in aortic dissection: a meta-analysis. Eur Heart J 2006;27:489-98. [Reference]