100 Questions in Cardiology - Part 8 doc

FFuurrtthheerr rreeaaddiinngg Hardman SMC, Cowie M. Fortnightly review: anticoagulation in heart disease. BMJ 1999; 331188 : 238–244 (website version at www.bmj.com.) The Stroke Prevention in Atrial Fibrillation Investigators. Predictors of thromboembolism in atrial fibrillation I. Clinical features of thrombo- embolism in atrial fibrillation. Ann Intern Med 1992; 1 11166 : 1–5. The Stroke Prevention in Atrial Fibrillation Investigators. Predictors of thromboembolism in atrial fibrillation II. Echocardiographic features of patients at risk. Ann Intern Med 1992; 111166 : 6–12. 150 100 Questions in Cardiology 72 How sensitive are transthoracic and transoesophageal echocardiography for the detection of thrombus in the left atrium? Suzanna Hardman and Martin Cowie The ability of echocardiography to detect left atrial clot is determined by the sophistication of the equipment, the ease with which the left atrium and left atrial appendage can be scanned and the skill and experience of the operator. Historically, at best, the sensitivity of two dimensional transthoracic echo- cardiography for detecting left atrial thrombus has been of the order of 40–65%, with the left atrial appendage visualised in under 20% of patients even in experienced hands. This compared with a reported sensitivity of 75–95% for visualising left ventricular thrombi from the transthoracic approach. More recent data, from a tertiary referral centre using the new gener- ation transthoracic echocardiography, suggest the left atrial appendage can be adequately imaged in 75% of patients and that within this group 91% of thrombi identified by trans- oesophageal echocardiography will also be visualised from the transthoracic approach. Although encouraging, the extent to which these figures can be reproduced using similar equipment by the generality of units remains to be established. Available data for the sensitivity of transoesophageal echo- cardiography in detecting left atrial and left atrial appendage thrombus consistently report a high positive predictive value. The largest series of 231 patients identified thrombus ranging from 3 to 80mm in 14 patients: compared with findings at surgery this produced a sensitivity of 100%. But these findings need to be interpreted with considerable caution and are unlikely to be ap- plicable to all users of the technique. The study was carried out in a tertiary referral centre with a particular interest and long-standing investment in the technique and the nine observers involved in reporting the data all had extensive experience. Nonetheless, transoesophageal echocardiography is undoubtedly the investi- gation of choice for imaging the left atrium and left atrial appendage. 100 Questions in Cardiology 151 FFuurrtthheerr rreeaaddiinngg Aschenberg W, Schiuter M, Kremer P et al. Transoesophageal two- dimensional echocardiography for the detection of left atrial appendage thrombus. J Am Coll Cardiol 1986; 77 : 163–6. Manning WJ, Weintraub RM, Waksmonski CA et al. Accuracy of trans- oesophageal echocardiography for identifying left atrial thrombi. A prospective intraoperative study. Ann Intern Med 1995; 112233 : 817–22. Omran H, Jung W, Rabahieh R et al. Imaging of thrombi and assessment of left atrial appendage function: a prospective study comparing trans- thoracic and transoesophageal echocardiography. Heart 1999; 8811 : 192–8. Schweizer P, Bardos P, Erbel R et al. Detection of left atrial thrombi by echocardiography. Br Heart J 1981; 4 455 : 148–56. 152 100 Questions in Cardiology 73 What are the roles of transthoracic and transoesophageal echocardiography in patients with a TIA or stroke? Diana Holdright Approximately 80% of strokes are ischaemic in origin, of which 20–40% have a cardiac basis. TIAs have a cardiac cause in ~15% of cases. Common cardiac abnormalities associated with neuro- logical events include atrial fibrillation, mitral valve disease, left atrial enlargement, left ventricular dilatation, prosthetic valve abnormalities and endocarditis. Clinical examination and simple tests (CXR and ECG) should indicate cardiac abnormality in these situations. The aim of echocardiography is to confirm the presence of important predisposing cardiac abnormalities and in younger patients, typically <50 years, to look for rare cardiac causes that might not be detected by other means. This latter group includes atrial septal aneurysm and patent foramen ovale (PFO) which, although somewhat controversial, are associated with an increased risk of stroke in patients without other detectable abnormalities. Consequently, echocardiography is particularly useful in patients at both ends of the age scale. Older patients are more likely to have cardiac abnormalities that could give rise to stroke/TIA and young patients frequently have apparently normal hearts, but echocardiography (especially trans- oesophageal) may indicate the presence of an atrial septal aneurysm or PFO. The pick-up rate of transthoracic echocardiog- raphy is extremely low in patients with a normal clinical exami- nation, CXR and ECG, making it a poor screening test. Conversely, the yield in patients with clinical abnormalities or an abnormal ECG/CXR is high and may give useful information for risk strat- ification beyond simply confirming a clinical diagnosis, for example left atrial size and the presence of spontaneous contrast. Transoesophageal echocardiography should be reserved for “younger” patients (empirically <50 years) with unexplained stroke/TIA, for patients in whom the transthoracic study is unclear, and for older patients with repeated unexplained stroke/TIA. Transoesophageal echocardiography is particularly useful for looking at the left atrium, atrial septum, left atrial appendage, mitral valve and thoracic aorta, abnormalities of which may give 100 Questions in Cardiology 153 rise to stroke/TIA. There is a tendency to over-report more subtle abnormalities (e.g. slight mitral valve prolapse) that may not be clinically relevant. FFuurrtthheerr rreeaaddiinngg Nighoghossian N, Perinetti M, Barthelet M et al. Potential cardioembolic sources of stroke in patients less than 60 years of age. Eur Heart J 1996; 1177 : 590–4. Pearson AC, Labovitz AJ, Tatineni S et al. Superiority of trans- oesophageal echocardiography in detecting cardiac source of embolism in patients with cerebral ischaemia of uncertain aetiology. J Am Coll Cardiol 1991; 1 177 : 66–72. 154 100 Questions in Cardiology 74 Which patient with a patent foramen ovale should be referred for closure? Diana Holdright A patent foramen ovale (PFO) occurs in approximately one quarter of the population. It is a vestige of the fetal circulation, with an orifice varying in size from 1 to 19mm, allowing right-to- left or bidirectional shunting at atrial level and the potential for paradoxical embolism. The development of better imaging techniques (e.g. transoesophageal echocardiography, contrast agents) and the fact that 35% of ischaemic strokes remain unex- plained has generated interest in the potential for paradoxical thromboembolism through a PFO. Studies of patients with cryptogenic stroke give a higher incidence of PFO (up to 56%) 1 than in a control population, suggesting, but not proving, causality. Stroke due to paradoxical embolism involves the passage of material across a PFO, at a time when right atrial pressure exceeds left atrial pressure, to the brain. In one study the incidence of venous thrombosis as the sole risk factor for presumed embolic stroke in patients with PFOs was 9.5% and was clinically silent in 80% of patients, 2 adding support to the concept of paradoxical embolism. The detection of venous thrombosis is not without difficulty and venous thrombi may resolve with time, such that a negative study does not exclude prior thrombosis. There is evidence that PFOs allow right-to-left shunting under normal physiological conditions, during coughing, straining and similar manoeuvres and especially in patients with raised right heart pressures and tricuspid regurgitation. There are no completed prospective trials comparing aspirin, warfarin and percutaneous closure to guide management of patients with an ischaemic stroke presumed to be cardioembolic in origin. Opinion is divided in the case of a single ischaemic lesion on MR imaging and an isolated PFO – there is no evidence in favour of any particular strategy. Aspirin therapy is an uncomplicated option, and easier and safer than life-long warfarin. If there is evidence of more than one ischaemic lesion, no indication for warfarin (e.g. a procoagulant state), preferably a history of a Valsalva manoeuvre or equivalent immediately preceding the stroke and no alternative cause for the stroke then I would consider percutaneous closure, which has rapidly 100 Questions in Cardiology 155 developed as a highly effective and technically straightforward procedure for closure of PFOs and many atrial septal defects. RReeffeerreenncceess 1 Cabanes L, Mas JL, Cohen A et al. Atrial septal aneurysm and patent foramen ovale as risk factors for cryptogenic stroke in patients less than 55 years of age. Stroke 1993; 2244 : 1865–73. 2 Lethen H, Flachskampf FA, Schneider R et al. Frequency of deep vein thrombosis in patients with patent foramen ovale and ischemic stroke or transient ischemic attack. Am J Cardiol 1997; 8800 : 1066–9. 156 100 Questions in Cardiology 75 How should I investigate the patient with collapse? Who should have a tilt test, and what do I do if it is positive? RA Kenny and Diarmuid O’Shea Investigation of a patient with collapse The history from the older patient may be less reliable, however a careful history often allows syncopal episodes to be classified into broad diagnostic categories (Table 75.1). Elderly patients may have amnesia for their collapse. A witness history, available in only 40–60% of cases, can thus be invaluable. Witnessed features of prodrome (i.e. pallor, sweating, loss of consciousness or fitting) and clinical characteristics after the event can all help in building a diagnostic picture. Physical examination should include an assessment of blood pressure in the supine and erect position, a cardiovascular examination to look for the presence or absence of structural heart disease (including aortic stenosis, mitral stenosis, outflow tract obstruction, atrial myxoma or impaired left ventricular function) and auscultation for carotid bruits. The 12- lead electrocardiogram (ECG) remains an important tool in the diagnosis of arrhythmic syncope. Up to 11% of syncopal patients have a diagnosis assigned from their ECG. More importantly those with a normal 12-lead ECG (no QRS or rhythm distur- bance) have a low likelihood of arrhythmia as a cause of their syncope and are at low risk of sudden death. Thus the history and physical examination can guide you as to the more appropriate diagnostic tests for the individual patient and would include the following: • ECG • 24 hour ECG • 24 hour BP • Carotid sinus massage – supine and erect (only if negative supine) • External loop recorder • Electrophysiological studies • Head up tilt test • CT head and EEG if appropriate • Implantable loop recorder 100 Questions in Cardiology 157 TTaabbllee 7755 11 CClliinniiccaall ffeeaattuurreess ssuuggggeessttiivvee ooff aa ssppeecciiffiicc ccaauussee ooff ssyynnccooppee DDiiaaggnnoossttiicc ccoonnssiiddeerraattiioonn SSyymmppttoomm oorr ffiinnddiinngg NNeeuurraallllyy mmeeddiiaatteedd Carotid sinus syncope Syncope with head rotation Vasovagal syncope After pain, unpleasant sight or sound Prolonged standing Athlete after exertion Situational Micturition, cough, swallow, defecation Orthostatic On standing Post-prandial After meals C Caarrddiiooggeenniicc Structural heart disease – aortic Syncope on exertion and mitral stenosis Ischaemic heart disease NNoonn ccaarrddiioovvaassccuullaarr Seizures Witness fitting Cerebrovascular disease Associated with vertigo, dysarthria, diplopia or other motor and sensory symptoms of brain stem ischaemia Subclavian steal Syncope with arm exercise Modified from Kenny RA ed., Syncope in the older patient. Chapman and Hall Medical 1996. 158 100 Questions in Cardiology Who should have a tilt test? Kenny et al in 1986 were the first to demonstrate the value of head up tilt testing in the diagnosis of unexplained syncope. 1 There is a broad group of hypotensive syndromes and conditions where head up tilt testing should be considered – patients with recurrent syncope or presyncope and high risk patients with a history of a single syncopal episode (serious injury during episode, driving) where no other cause for symptoms is suggested by initial history, examination or cardiovascular and neurological investigations. Tilt table testing may also be of use in the assessment of elderly patients with recurrent unexplained falls and in the differential diagnosis of convulsive syncope, orthostatic hypotension, postural tachycardia syndrome, psychogenic and hyper- ventilation syncope and carotid sinus hypersensitivity. What do you do if you make a diagnosis of vasovagal syncope on history and head up tilt test? As a result of the complexity of the aetiology of vasovagal syncope and the lack of a single well evaluated therapeutic intervention there are many treatments available. These have recently been reviewed, 2 and the following algorithm for management of vaso- vagal syncope suggested (Algorithm 75.1). RReeffeerreenncceess 1 Kenny RA, Ingram A, Bayliss J et al. Head-up tilt: a useful test for investigating unexplained syncope. Lancet 1986; ii : 1352–4. 2 Parry SW, Kenny RA. The management of vasovagal syncope. Q J Med 1999; 9 922 : 697–705. F Fuurrtthheerr rreeaaddiinngg Kenny RA, O’Shea D, Parry SW. The Newcastle protocols for head-up tilt table testing in the diagnosis of vasovagal syncope and related disorders. Heart 2000; 8833 : 564–9. 100 Questions in Cardiology 159 [...]... defibrillator is recognising the ventricular, and not atrial, pacing spike Modern systems have increasingly effective protection from external interference 100 Questions in Cardiology 171 81 What do I do about non-sustained ventricular tachycardia on a 24 hour tape? Simon Sporton The term non-sustained ventricular tachycardia (VT) is used conventionally to describe salvos lasting a minimum of four consecutive... asymptomatic nonsustained VT and inducible, non-suppressible VT following myocardial infarction However, many important questions 172 100 Questions in Cardiology remain about the prophylactic implantation of ICDs in such patients The decision to implant is easier if there is a history of presyncope or syncope Further reading Buxton AE, Marchlinski FE, Waxman HL et al Prognostic factors in 5 nonsustained ventricular... symptoms of dizziness and 7 syncope Chest 1990;77: 722–5 100 Questions in Cardiology 163 7 DiMarco P, Philbrick JT Use of ambulatory electrocardiographic 1 (Holter) monitoring Ann Intern Med 1990;113: 53– 68 8 Bass EB, Curtiss EI, Arena VC The duration of holter monitoring in 1 patients with syncope: is 24 hours enough? Arch Intern Med 1990;150: 1073 8 9 Linzer M, Pritchett ELC, Pontiueu M et al Incremental... symptomatic bradycardia Report of a working party of the British Pacing and Electrophysiology Group Br Heart J 6 1991;66: 185 –91 100 Questions in Cardiology 167 2 Andersen HR, Thuesen L, Bagger JP et al Prospective randomised trial of atrial versus ventricular pacing in sick-sinus syndrome Lancet 3 1994;344: 1523 8 3 Gregoratos G, Cheitlin MD, Conill A et al ACC/AHA guidelines for implantation of cardiac... ventricular pacing should be established rapidly although it is almost certainly wise to stabilise the patient first with an isoprenaline infusion (at a rate of 1-1 0micrograms/min, titrated against the heart rate) or external cardiac pacing There is experimental and clinical evidence to support the use of intravenous magnesium in the acute treatment of torsade A dose of 8mmol (administered over 1 0-1 5 minutes)... cardioversion, particularly with the increasing use of pacing techniques in the management of paroxysmal atrial fibrillation Some centres reprogramme or inactivate pacemakers prior to cardioversion The decision regarding this should be made on an individual basis, depending on the type of pacemaker, reason for implant, and pacing-dependency Patients needing cardioversion should have the paddles applied in a... loading Still symptomatic Still symptomatic ␤ Blocker/SSRI Still symptomatic/ cannot tolerate/ contraindicated Fludrocortisone and/or Midodrine Consider: tilt training, fluid therapy, anticholinergic, enalapril, oral theophylline Algorithm 75.1 Management of vasovagal syncope Still symptomatic 100 Questions in Cardiology 161 76 What are the chances of a 24 hour tape detecting the causes for collapse in. .. testing, the underlying cause of syncope remains unexplained and continues to pose a diagnostic problem The implantable loop recorder (ILR) is a new diagnostic tool to add to the strategies for investigation of unexplained syncope.12 It permits long term cardiac monitoring to capture the ECG during a spontaneous episode in patients without recurrence in a reasonable time frame It should be considered in. .. spontaneous remission making it a difficult diagnostic challenge Thus even after a thorough work up, the cause of syncope may remain unexplained in up to 40% of cases.4 Prolonged ambulatory monitoring is often used as a first line investigation Documentation of significant arrhythmias or syncope during monitoring is rare At best, symptoms correlating with arrhythmias occur in 4% of patients, asymptomatic... prolongation of the PR interval results in “trifascicular block” implying abnormal conduction through or above the remaining fascicle The concern is that conduction will fail in the remaining fascicle, i.e complete heart block will develop with a slow and unreliable ventricular escape rhythm Potential consequences include syncope and death There have been no randomised trials of pacing vs no pacing in patients . recurrences in patients with syncope. Am J Med 1 987 ; 88 33 : 700 8. 12 Kenny RA, Krahn AD. Implantable loop recorder: evaluation of unexplained syncope. Heart 1999; 88 11 : 431–3. 100 Questions in Cardiology. be ap- plicable to all users of the technique. The study was carried out in a tertiary referral centre with a particular interest and long-standing investment in the technique and the nine observers. echocardiography. Heart 1999; 88 11 : 192 8. Schweizer P, Bardos P, Erbel R et al. Detection of left atrial thrombi by echocardiography. Br Heart J 1 981 ; 4 455 : 1 48 56. 152 100 Questions in Cardiology 73 What