Essential Revision Notes for MRCP Third Edition - PasTest

Essential Revision Notes for MRCPechocardiography) and direct pulmonary angiographycan be performed. Direct pulmonary angiographyhas now been largely replaced by CTangiography.Complications of cardiac catheterisationComplications are uncommon (approximately 5%,including minor complications); these include contrastallergy, local haemorrhage from puncture siteswith subsequent occurrence of thrombosis, falseaneurysm or arteriovenous (AV) malformation. Vasovagalreactions are common. Other complicationsare:• Coronary dissection (particularly the rightcoronary artery in women) and aortic dissectionor ventricular perforation• Air or atheroma embolism: in the coronary orother arterial circulations, with consequentischaemia or strokes• Ventricular dysrhythmias: can even cause deathin the setting of left main stem disease• Mistaken cannulation and contrast injection intothe conus branch of the right coronary arterycan cause ventricular fibrillation• Overall mortality rates are quoted at ,1/1000cases1.2.5 Exercise stress testingThis is used in the investigation of coronary arterydisease, in exertion-induced arrhythmias, and in theassessment of cardiac workload and conductionabnormalities. Exercise tests also give diagnosticand prognostic information post-infarction, and generatepatient confidence in rehabilitation after MI.Diagnostic sensitivity is improved if the test is conductedwith the patient having discontinued antianginal(especially rate-limiting) medication.The main contraindications to exercise testing includethose conditions where fatal ischaemia orarrhythmias may be provoked, or where exertionmay severely and acutely impair cardiac function.These include the following:• Severe aortic stenosis or HCM with markedoutflow obstruction• Acute myocarditis or pericarditis• Pyrexial or coryzal illness• Severe left main stem disease• Untreated congestive cardiac failure• Unstable angina• Dissecting aneurysm• Ongoing tachy- or bradyarrhythmias• Untreated severe hypertensionIndicators of a positive exercise test resultThe presence of each factor is additive in the overallpositive prediction of coronary artery disease:• Development of anginal symptoms• A fall in BP of .15 mmHg or failure to increaseBP with exercise• Arrhythmia development (particularlyventricular)• Poor workload capacity (may indicate poor leftventricular function)• Failure to achieve target heart rate (allowing forâ-blockers)• .1 mm down-sloping or planar ST-segmentdepression, 80 ms after the J point• ST-segment elevation• Failure to achieve 9 min of the Bruce protocoldue to any of the points listedExercise tests have low specificity in the followingsituations (often as a result of resting ST-segmentabnormalities):• Ischaemia in young women with atypical chestpains• Atrial fibrillation• LBBB• WPW syndrome• LVH• Digoxin or â-blocker therapy• Anaemia• Hyperventilation• Biochemical abnormalities such ashypokalaemia12