TILT TESTING INFORMATION AND PROTOCOLS

Transcription

1 TILT TESTING INFORMATION AND PROTOCOLS For technicians and doctors June 2008 Dr Nicola Cooper Consultant in Acute Medicine & Geriatrics

2 TILT TESTING This information has been compiled for technicians and doctors working in the tilt testing service at the Leeds Teaching Hospitals NHS Trust. Overview Introduction to tilt testing Indications Contraindications The Leeds tilt test protocol Responses to tilt testing Writing the report Carotid sinus massage in the tilt lab Autonomic function tests in the tilt lab Referrals Further resources and contacts Supervising consultants Introduction to tilt testing Tilt testing is used to investigate syncope (pronounced sin-cope-ee). Syncope comes from the Greek to interrupt and it is a common medical problem. Syncope occurs when there is transient global cerebral hypoperfusion (in other words, not enough blood to the brain). This can be either due to low blood pressure or a heart problem. In Leeds we follow the European Society of Cardiology guidelines on the investigation and management of syncope. These can be found at In a nutshell, when a person presents with one or more blackouts, the main way to diagnose the problem is by a careful history. The history (including an eye-witness account) is everything! The ESC guidelines say that the initial evaluation should include: History Examination (of the heart in particular) 12-lead ECG Lying and standing blood pressure In a significant proportion of patients, the diagnosis will be obvious after the initial evaluation (especially if an expert has done it) and no tests are needed. If the person has no structural heart disease (ie no cardiac history, no murmurs and a normal ECG - and in young people no family history of sudden cardiac death) then the chances of syncope being due to a cardiac arrhythmia are slim. In fact, in one study, a normal ECG virtually excluded an arrhythmia as the cause of syncope. 2

3 Tilt testing is used as a first line test in unexplained syncope when a cardiac arrhythmia is unlikely. In the over 50 s carotid sinus massage may be indicated as well. Tilt testing is also used when the diagnosis is suspected, but it would be helpful to prove it in certain patients. There are 4 main types of syncope: Neurally mediated Orthostatic (postural) hypotension - OH Cardiac arrhythmias Structural eg aortic stenosis or HOCM By far the most common cause of syncope is neurally mediated. Cardiac arrhythmias account for around 20% of all syncope. In older people, low blood pressure and orthostatic hypotension are much more common than neurally medicated syncope. What is neurally mediated syncope? The term refers to a fainting reflex which is triggered in certain people. Neurally mediated syncope includes vasovagal syncope (normal fainting), situational syncope (people who faint in certain situations eg unpleasant stimuli) and carotid sinus hypersensitivity. Orthostatic hypotension is when the blood pressure falls immediately on standing, due to impaired autonomic reflexes. It is common in old people, often exacerbated by drugs, or can be due to diseases eg diabetes. There is another common pattern in older people, often termed the elderly dysautonomic pattern - this is a slow fall in BP after standing which goes undetected on normal lying and standing BPs. Older people with this problem commonly faint without typical warning symptoms. The next page has a summary diagram of the ESC guidelines on the investigation of syncope. Technicians and doctors are encouraged to read the full guideline. 3

4 Summary of the ESC guidelines Is it syncope? (The history may suggest another diagnosis). No Other treatment Yes Initial evaluation Obvious diagnosis in a large proportion of patients - treat. Suspected diagnosis Unexplained syncope Cardiac syncope likely - do relevant heart tests eg monitor, Echo, Reveal device, electrophysiology etc Neurally mediated syncope likely - do tilt test + CSM (autonomic function tests where relevant) Unexplained means after evaluation by an expert clinician. Investigate only if recurrent or single but serious (eg injury or whilst driving) - do neurally medicated syncope tests first. Treat any diagnosis. If the initial tests are all negative, re-evaluate the patient and think about other syncope tests. CSM = carotid sinus massage. 4

5 Indications Indications for tilt testing are described in the diagram above. In addition, tilt testing is sometimes useful for: Differentiating syncope with myoclonic jerks from seizures Evaluating patients with unexplained falls (which are often due to brief syncope) Assessing recurrent pre-syncope symptoms Demonstrating the benign nature of the condition to patients who need reassurance about their syncope When the particular cardiovascular response during syncope may be useful in deciding treatment Contraindications Contraindications to tilt testing include: Patient refusal Morbid obesity (technicians cannot tilt safely) Unable to stand for long periods due to pain Pregnancy Recent (within 6 months) myocardial infarction or stroke/tia A known tight stenosis anywhere (eg heart valve, LV outflow obstruction, coronary or carotid/cerebrovascular artery) In atrial fibrillation, the accuracy of beat-to-beat blood pressure monitoring may be impaired and this should be taken in to account when considering a tilt test. In Leeds we do not provide a tilt test service for patients under the age of 16. The Leeds tilt test protocol There are various tilt testing protocols in use (eg the Newcastle and Italian protocols). In Leeds we use our own protocol using lower body negative pressure, this is based on extensive previous research. Tilt testing aims to reproduce what happens when a person has neurally mediated or OH syncope at home - but we monitor his or her physiology to help us confirm the diagnosis and choose the right treatment. It is an extremely safe test provided the contraindications are observed. There are no reported deaths during tilt testing in the world literature. In the Leeds tilt test protocol: Patients are asked whether they need to empty their bladder and that any support stockings are removed before the test The test is explained 5

6 Patients lay supine for 15 minutes and the monitoring equipment is attached Patients are tilted at o upright for 20 minutes If the test end points have not yet been reached, then -20mmHg lower body negative pressure is applied for 10 minutes If the test end points have not yet been reached, then -40mmHg lower body negative pressure is applied for a further 10 minutes If the test end points have not yet been reached, the test ends here. Lower body negative pressure is a way of fooling the body in to thinking it has been standing for a long time - without taking a long time. Ideally, tilt testing should be carried out in a quiet room with dim lights and the patient should fast for 2 hours before the test. The test can be supervised by technicians, but it is recommended that a doctor should be available nearby (eg in the next door clinic) should any problem or query arise. The following monitoring is carried out during a tilt test: Continuous non-invasive beat-to-beat blood pressure Intermittent blood pressure (either Dynamap or manual) every 5 minutes Continuous 3-lead ECG Continuous end-tidal CO 2 using nasal cannulae and a capnograph The blood pressure and heart rate during the test should be documented every 2 minutes. If the end-tidal CO 2 goes below 30 mmhg (4.0 kpa), this should be documented as it indicates hyperventilation which is important know about. A crash trolley and resuscitation equipment should be available in the same room as the tilt test. The reason for this is that rarely patients may develop arrhythmias. For example, young people with neurally mediated syncope (especially situational syncope) tend to get transient asystole. But remember - this is what is happening to them at home when they faint anyway. If the patient is laid flat immediately then he or she will recover. Tilt test end points The tilt test should be stopped and the patient laid flat immediately when: Systolic blood pressure falls below 80 mmhg - or is falling rapidly Heart rate falls below 50 /min - or is falling rapidly Heart rate rises above 170 /min Acute arrhythmia Hyperventilation leading to an end-tidal CO 2 of less than 20 mmhg if not able to bring it under control Patient distress or discomfort 6

7 The end of the protocol has been reached Responses to tilt testing A positive tilt test is when the patient s syncopal or pre-syncopal symptoms are reproduced and accompanied by hypotension, bradycardia (relative or otherwise) or both. Heart rate and blood pressure changes in isolation should not prompt a diagnosis of neurally mediated or OH syncope. (However - in elderly patients this may not apply as they tend to get few warning symptoms). Anyone can faint during a tilt test. Just because the test is positive does not mean that is the reason for a person s blackouts. In the same way, sometimes a person with neurally mediated syncope may have a negative tilt test. This is because there is no such thing as a perfect test. All tests have something called a sensitivity (ability to pick up true diagnoses) and a specificity (ability to rule out non-diagnoses). Therefore a tilt test must always be interpreted in the light of the clinical evaluation. The interpretation of the tilt test and treatment plan afterwards is the responsibility of the referring doctor (as is advice about driving). However, the technician s report is key to understanding what the tilt test result means for the patient. There are several different possible positive responses to a tilt test. The same patient may have different responses at different times: Vasodepressor - the blood pressure falls but the heart rate does not fall by more than 10% from its peak. Cardio-inhibitory type A or cardio-inhibition without asystole - the heart rate falls to less than 40 /min for more than 10 seconds but asystole of more than 3 seconds does not occur. Cardio-inhibitory type B or cardio-inhibition with asystole - there is asystole of more than 3 seconds. Mixed - a mixture of a vasodepressor response and cardio-inhibitory type A response. Excessive heart rate rise - a heart rate that rises both at the onset of upright position and throughout its duration before syncope (greater than 130 /min). This is known as POTS (postural orthostatic tachycardia syndrome) and more can be read about this in the further resources. Chronotropic incompetence is another response in which there is no heart rate rise during the tilt test (ie less than 10% from baseline). Writing the report The technician s report is key in the further management of the patient. The referring clinician should be sent the typed tilt test service report sheet and a copy of the handwritten blood pressure and pulse record during the test. 7

8 The technician s report should include the information as outlined on the tilt test service report sheet (see next page). Key bits of information here are: The baseline BP and heart rate The change in BP and heart rate What the BP and heart rate was when the test was stopped Which tilt test end points (above) were reached However, one of the most important parts of the report is the free text observations of the technician supervising the test. Key bits of information here are: Whether the cardiac reflex response to head-up tilt was normal or not (see below*) At what point in the test the patient developed any symptoms If the patient did develop symptoms, are these the same as his or her usual symptoms before a blackout (the patient should be asked this at the end of the test) Whether there was hyperventilation or severe anxiety during the test If the patient had a blackout during the test but the blood pressure and heart rate were normal, a detailed description of what happened is extremely useful (as this could be psychogenic syncope) *The normal response when a person moves from supine to upright during a tilt test is for the heart rate to increase and the blood pressure to remain the same. Some people with blunted autonomic responses (or those who are paced) will not demonstrate an increase in heart rate, and this is useful to document. In older people there may be a transient drop in blood pressure on head-up tilt which recovers back to normal within seconds. This immediate postural hypotension would be missed on manual BP monitoring and is important to document. The free text observations are useful as a summary of what happened during the test. For example: after 20 minutes of head-up tilt, during which there was a stable BP and heart rate, the BP and heart rate fell quickly, associated with symptoms of feeling hot and dizzy. The BP, heart rate and symptoms resolved quickly after being laid flat. (This would be a typical scenario in someone with vasovagal syncope). Or: after head-up tilt, the BP was observed to fall gradually over 15 minutes without any symptoms until the systolic BP was 70 and then the patient said he felt queer and the test was stopped. Heart rate remained between 60 and 70 bpm throughout. (This would be a typical scenario in an older person with unexplained falls who is demonstrating a common dysautonomic pattern on tilt testing). The next page shows the tilt test service report sheet, with the key bits of information used to make a diagnosis highlighted. 8

9 LEEDS TEACHING HOSPITALS NHS TRUST NHS Tilt Test Service Cardio-Respiratory Unit 1st Floor Chancellor Wing St James s University Hospital Phone: / Fax: Patient: Address: DOB: Hospital no: NHS no: TILT TEST REPORT Test(s) performed: Test date: Referring consultant: Referrer s location: Billing category: The tilt test service takes many external referrals which it bills for. Leeds protocol: head-up tilt for 20 minutes, then with LBNP -20 mmhg for 10 minutes, then with -40 mmhg for a further 10 minutes, then end. Response to head-up tilt alone (nb - please see enclosed BP and heart rate record) Heart rate Systolic BP Diastolic BP Supine (predicted) Change (predicted) Response to head-up tilt and lower body negative pressure (LNBP) Describe which of the test endpoints were reached. Time to stop test mins Predicted: Average: Reason for stopping test Symptoms Max heart rate Heart rate at end of test BP at end of test bpm Average predicted: bpm mmhg Technician s report below This part is very important. The referrer needs to know what the heart rate and BP was when the decision was taken to stop the test. Technician s name: What symptoms the patient had, if any, and whether he or she says these are the same as in their usual collapses. Time to stop the test is important. The predicted or average time is the time it takes for a normal person to reach the test endpoints. This data is held in the tilt test lab. The referrer will compare the patient s time to the predicted time. 9

10 Carotid sinus massage in the tilt lab Carotid sinus hypersensitivity (CSH) is a condition found in the over 40 s, especially men. The carotid body is located at the site of the carotid artery bifurcation in the neck. Pressure at this site causes a reflex slowing of the heart rate and fall in blood pressure. In people with CSH, this reflex is hypersensitive, and causes syncope - usually without a warning. Only rarely is there a history of syncope on head turning which gives a clue as to the condition. Carotid sinus massage (CSM) is therefore sometimes indicated as a test in syncope or unexplained falls (which are actually brief syncope). It may be requested in patients at the same time as a tilt test unless the tilt test is positive (by which the referring clinician means and fall in BP and/or heart rate in response to head-up tilt with associated symptoms). CSM should be performed by a doctor who will double-check any contraindications, explain the procedure again to the patient and deal with any potential complications. The informed consent for CSM, including an explanation of the potential complications, is the responsibility of the referring clinician. The referring clinician should also ensure that there are no contraindications to the procedure and this should be documented in the notes and/or referral letter. This is because the doctor present in the tilt lab will usually be a registrar who does not know the patient. When in doubt, the registrar should seek advice from either the referring clinician or the designated supervising cardiologist in the next door clinic. CSM is ideally performed in the tilt lab because in at least 30% of cases, a positive response is only present in the upright position. Further more, the blood pressure response is important to document, as some people get a transient significant fall in BP without a significant fall in heart rate. This can only be picked up by the beat-to-beat BP monitor (Finapres) in the tilt lab. Indications for CSM CSM is indicated in patients over the age of 40 with syncope or unexplained falls in which the history, clinical examination and relevant cardiology and neurology tests have not clearly identified a cause of the symptoms. Contraindications to CSM The contraindications to CSM are: Patient refusal Morbid obesity (technicians cannot tilt safely) Recent (within 6 months) myocardial infarction or stroke/tia Any previous adverse reaction to CSM Previous VF or VT A carotid stenosis of 50% or more (or a known tight stenosis elsewhere as in the contraindications for tilt testing) 10

11 The referring clinician is responsible for listening to the carotids to detect any bruit before requesting the test. If a carotid bruit is present then carotid Doppler ultrasonography should be performed prior to CSM. (It is known that the presence of a bruit does not correlate with the severity of any carotid stenosis, but this is the safe and pragmatic approach to practice that UK syncope services take). Potential complications of CSM Complications of CSM are rare. The main complication is transient neurological signs (TIA) or stroke. Studies report complication rates of between 0.17 and 0.45% - ie around 1 in If neurological signs develop the patient should be laid flat immediately and measures taken to rapidly restore the blood pressure to normal. Aspirin 300mg should be given if not contraindicated and the patient should be admitted. More rarely, CSM can give rise to transient atrial fibrillation. VT or VF never occurred in 16,000 CSMs in one study. How to do CSM CSM should be performed by a clinician who knows how to manage the potential complications. The patient lays supine for 5 minutes and the monitoring equipment is attached Still supine, the right side is massaged first (as up to 66% of subjects are positive on this side) CSM is performed at the site of maximal pulsation over the carotid sinus, which is located between the thyroid cartilage and the angle of the mandible Using the middle three fingers, firm pressure is applied and the sinus is massaged longitudinally for 5 seconds Massage should be discontinued if asystole of more than 3 seconds occurs The following monitoring is carried out during the test: Continuous non-invasive beat-to-beat blood pressure Continuous 3-lead ECG, capable of printing during CSM Intermittent blood pressure (either Dynamap or manual) at the start of the test to calibrate with the Finapres monitor If there is no significant change in BP or heart rate (see below) and no symptoms, then the left side is massaged supine. If supine CSM is negative on both sides then the procedure is repeated with the patient tilted upright at 11

12 60-70 o, again starting with the right side. At least 60 seconds should be left between each massage. If at any time CSM is positive then the procedure is terminated and the patient laid flat. After CSM the patient should lay flat for at least 10 minutes, which reduces the likelihood of neurological complications. Responses to CSM Carotid sinus hypersensitivity is diagnosed when CSM produces: More than 3 seconds asystole (cardio-inhibitory type) More than 50 mmhg fall in systolic BP (vasodepressor type) Both of the above (mixed type) And the patient has symptoms (dizziness or syncope) Recurrent syncope due to cardio-inhibitory carotid sinus hypersensitivity - in the absence of drugs which depress the sinus node or AV node conduction - is an indication for a dual chamber pacemaker. The heart rate response to CSM occurs immediately, but the BP response is maximal at 18 seconds after the start of CSM, returning to baseline at 30 seconds. The BP response is important to document. The results of CSM are documented as free text, enclosing the printout of the 3-lead ECG, with arrows to indicate the start of right or left, supine or upright CSM. Autonomic function tests in the tilt lab Autonomic function tests are sometimes requested for patients who may have autonomic neuropathy. This condition causes often profound postural hypotension. There are 2 parts to the autonomic function test provided by the tilt test service: Active standing test Valsalva manoeuvre Active standing test This is a simple lying and standing blood pressure test using the non-invasive beat-to-beat BP monitor (Finapres). It is more useful in evaluating symptoms of postural (orthostatic) hypotension than the tilt test because we want to assess the patient with his or her active muscle involvement during standing (the reasons for this are complex!) 12

13 During an active standing test: The patient lays supine for 5 minutes and the monitoring equipment is attached The patient stands The BP and heart rate response is monitored The test ends after 2 minutes of standing The supine BP and heart rate is documented, then immediately upright, then every 30 seconds until 3 minutes has elapsed. Orthostatic hypotension is defined as a fall in systolic BP of at least 20 mmhg and/or diastolic BP of at least 10 mmhg within 3 minutes of standing. The lowest systolic BP in the upright position should be recorded. In some patients the BP can change rapidly, which is why the Finapres is used. Some patients have a significant immediate drop in BP which recovers very quickly and this is important to document. Valsalva manoeuvre The Valsalva manoeuvre is used to test whether a patient has a normal autonomic response. The patient is asked to blow in to the outer part of a 20 ml syringe attached to a mercury sphygmanometer He or she should blow so that the mercury is at 40 mmhg for 10 seconds During that time the BP and heart rate response is monitored The normal response is shown in the diagram below: 13

14 In a normal person, the effect of exhaling against an obstruction (the Valsalva manoeuvre) is as follows: Phase 1 - there is an initial rise in BP as blood is squeezed out of the thorax. Phase 2 - then the increased intrathoracic pressure causes a reduction in venous return and the BP falls. This stimulates the baroreceptor reflex (vasoconstriction and tachycardia) so the heart rate rises. Phase 3 - when the person stops exhaling the intrathoracic pressure suddenly drops and blood pools in the pulmonary vessels, so there is a transient further fall in BP. Phase 4 - BP returns to normal, but there is an overshoot because the compensatory baroreceptor reflex is still operating for a little bit longer. These phases are illustrated in the diagram. In a person with autonomic failure, the BP falls and remains low until the intrathoracic pressure is released. But there are no changes in heart rate and overshoot is absent. The best way to report the response to a Valsalva manoeuvre is to use the printout facility of the Finapres and mark the start and end of the exhalation. Autonomic function tests are only rarely requested in the tilt lab. Referrals The referral form for tilt testing can be found on the cardiology Intranet site. This form should be accompanied by a letter or a description of the patient s symptoms so that referrals can be screened by a consultant physician if the service requires this. A clinic letter alone is acceptable as a referral. Further resources and contacts For further reading and resources, please see the list below. There are a number of consultants with a special interest in syncope who can also be approached for general queries, further education or resources. They include Shona McIntosh, Nicola Cooper and the cardiologists listed below. Reading and resources: Benditt DG, Blanc JJ, Brignole M and Sutton R. The evaluation and treatment of syncope. A handbook for clinical practice. 2nd Edition. Eur Soc of Cardiology. Wiley-Blackwell, Oxford, (Would be worth getting a copy of this for the tilt test lab as this is the main syncope textbook). (The European Society of Cardiology guidelines on the investigation and management of syncope). Kenny RA, O Shea D, Parry SW. The Newcastle protocols for head-up tilt table testing in the diagnosis of vasovagal syncope, carotid sinus hypersensitivity and related disorders. Heart 2000: 83;

15 Parry SW and Kenny RA. Tilt table testing in the diagnosis of unexplained syncope. Q J Med 1999; 92: Bartoletti A, Alboni P, Ammirati F et al. The Italian Protocol : a simplified head-up tilt testing potentiated with oral nitroglycerin to assess patients with unexplained syncope. Europace 2000: 2; McIntosh SJ and Kenny RA. Carotid sinus syndrome in the elderly. Jou Royal Soc Med 1994: 87; Supervising consultants The tilt test lab will operate all day Wednesday and Thursday mornings. On Wed am the available consultant is Greg Reynolds, on Wed pm the available consultant is Rob Sapsford - both will be in the next door clinic. On Thurs am there will be a registrar in Acute Medicine in the tilt lab for training purposes and Dr Blaxhill will be the available consultant. Therefore any patients who might need carotid sinus massage should only be booked for Thursdays. The lab will need to ensure it has a list of dates when the Acute Medicine registrar is on nights or away. 15