Professor Richard Sutton from the Department of Cardiology, Imperial College speaks about Tilt testing remains a valuable asset.
Link to Article:
For more than 50 years, the head-up tilt test (TT) has been used to study heart rate/blood pressure adaptation to positional changes, model responses to haemorrhage, determine orthostatic hypotension, and analyze haemodynamic and neuroendocrine responses in congestive heart failure, autonomic dysfunction, and hypertension. Any of the participants in these studies encountered syncope as a result of the vasovagal reflex. As a consequence, tilt checking has become part of the clinical evaluation of syncope where the cause is unclear. As a consequence, clinical experience backs up TT's diagnostic importance. This is emphasized in evidence-based clinical practice guidelines, which provide recommendations for TT technique and analysis while also pointing out its weaknesses. As a result, TT continues to be a valuable therapeutic asset, one that has contributed greatly to our understanding of the pathophysiology of syncope/collapse and, as a result, has enhanced the treatment of syncopal patients.
The first paragraph is an introduction.
For more than half a century, physiologists and physicians have used the head-up tilt test (TT) to investigate heart rate and blood pressure adaptation to positional changes, to model responses to haemorrhage, to measure characteristics of orthostatic hypotension (OH), and to examine haemodynamic and neuroendocrine responses in congestive heart failure, autonomic dysfunction, and hypertension. Due to hypotension caused by TT (often followed by bradycardia/asystole), some participants suffered complete or near-total transient loss of consciousness (TLOC) during these studies. 1-4 As a result, starting in the late 1980s, TT was used in the clinical evaluation of syncope of unknown origin1 as a means of activating the vasovagal reflex in susceptible individuals by exposing them to a regulated orthostatic challenge in a healthy, monitored clinical laboratory setting. 0.5–8 However, Kulkarni et al.9 recently criticized the clinical usefulness of TT, promoting the less well-studied active stand test based on the assumption of lower cost and, possibly, greater convenience. Although recognizing TT's shortcomings, the aim of this analysis is to provide a counterpoint to Kulkarni et al.9's viewpoints by highlighting both TT's well-documented clinical importance and numerous practice guidelines' recommendations.
Tilt work is currently in progress:
When the past fails to offer a definitive reason for symptoms, a positive TT may be used to diagnose syncope/collapse.
ten, eleven If the history reveals a straightforward diagnosis, TT isn't necessary; however, TT may provide valuable patient education and reassurance, as well as pathophysiological proof of the underlying processes, which is crucial for choosing the right treatment. 12
Since its introduction into clinical practice, the approach and understanding of TT findings have grown.
1 Longer TTs, up to 2 hours at angles of 40–60 degrees, were used to cause vasovagal events in susceptible people at first. In order to improve test sensitivity, the test period was shortened, the head-up angle was specified as 60–80°, and other interventions were introduced. years 13–21 Drugs (e.g., isoproterenol, nitroglycerine, serotonin agonists) were administered alone or in combination with physical manoeuvres, such as carotid sinus massage. Several of these offensive steps increased TT sensitivity and are still used, but they may reduce specificity.
In a meta-analysis of 55 studies involving patients with unexplained syncope and asymptomatic controls without a history of syncope, Forleo et al.22 published a meta-analysis of patients with unexplained syncope and asymptomatic controls without a history of syncope. The authors omitted trials of less than ten patients and procedures with a tilt angulation of 60° or greater than 80°; the study included 4361 syncope patients (aged 41-17 years) and 1791 controls (aged 39-17 years). With a region under the curve of 0.84 [95 percent confidence interval (CI) 0.81–0.87], the overview receiver-operating curve showed strong overall ability to distinguish symptomatic patients from asymptomatic controls. Pharmacological protocols increased sensitivity but decreased specificity, as predicted. The highest diagnostic odds ratio (14.40; 95 percent CI 11.50–18.05) and sensitivity (66 percent; 95 percent CI 60–72 percent ) were found in tilt protocols that included nitroglycerine provocation.
The European Society of Cardiology (ESC)10 and the American College of Cardiology/American Heart Association/Heart Rhythm Society collaboration11 came to similar and closely coherent recommendations for TT in unexplained syncope after initial clinical assessment based on the preponderance of evidence and working independently (a few members of each group provided reviews of the other document). Furthermore, both groups suggested that when an autonomic disruption was suspected, TT (along with additional cardiovascular autonomic assessment, if necessary) could be the first step in the diagnostic process.
According to recent criticisms by Kulkarni et al.9, TT, like any diagnostic test, may be misused. Nonetheless, comprehensive experience and evidence-based practice guidance guidelines provide clear direction for its proper use and indicate when TT is a valuable, efficient diagnostic tool. Other orthostatic stressors (e.g., active standing, squat-stand test) may be considered, but they have not received the same level of scrutiny as TT as possible clinical methods, with the exception of initial and classic OH and postural orthostatic tachycardia syndrome, where active standing is well known, validated by data, and thus by guidelines. ten, eleven
Tilt and syncope testing:
Tilt-table imaging was used to evaluate sensitivity to the vasovagal reflex in patients with TLOC of unknown etiology. If the medical history is classic and diagnostic of reflex syncope, such testing is not needed for diagnosis. However, this is not always the case, particularly in older patients whose histories may be incomplete due to retrograde amnesia. 23
From history taking, four characteristics of TLOC can be deduced: I a propensity to fall as an expression of loss of motor control; (ii) amnesia for the duration of the TLOC; (iii) irregular reactions to speech/touch; and (iv) a limited duration (less than 5 minutes).
I concussion; (ii) syncope; (iii) epileptic seizures; (iv) psychogenic spells resembling syncope [psychogenic pseudosyncope (PPS)] or seizures [psychogenic non-epileptic seizures (PNES)]; and (v) intoxication/metabolic disorder (strictly not TLOC because length is >5 minutes).
It is frequently, but not always, possible to distinguish between these diagnostic agents using a thorough medical history that includes eyewitness reports.
TT is the safest next step in some patients with persistent apparent syncope for whom prior attempts at diagnosis have failed, and recommendations support this approach.
ten, eleven If PPS, PNES, or mechanical falls due to orthostatic intolerance are all possibilities, findings during TT would almost certainly be diagnostic. Electroencephalography (EEG) is commonly used in conjunction with TT and is considered important in PPS/PNES. 24 In OH, TT allows for safe long-term blood pressure monitoring without the possibility of falling or injury that may occur during active stand or squat-stand tests. When it comes to recording immediate OH, however, TT is less successful than active standing, which is why the latter is recommended. ten, eleven
Several findings indicate that observed syncope/collapse associated with positive TT is comparable to spontaneous vasovagal syncope (VVS), but it should be noted that tilt-induced syncope is not the same as VVS. On implantable loop recorders (ILR), for example, bradyarrhythmias are more prominent than during TT. 6 VVS diagnosis varies from TT in that it is based on the patient's recognition of symptom replication (Figure 1). As a consequence, TT can be helpful in VVS diagnosis but not so much in therapy selection.
Tilt testing is an important and effective diagnostic method. The importance of it is endorsed by practice guidelines based on published and thoroughly vetted data. TT strengthens our comprehension of the pathophysiology of syncope/collapse and makes us to care for our patients. Active standing and ILR/ICMs can't replace TT; active standing is useful in certain types of OH but hasn't been shown to be useful in other syncope presentations, while ILR/ICMs are a useful addition to syncope workup.
R.S. is a consultant for Medtronic Inc., a member of Abbott Laboratories Inc.'s speakers bureau, and a stockholder in Edwards Lifesciences Corp. and Boston Scientific Inc. D.G.B. receives funding from the Dr Earl E Bakken Family for heart-brain research and reports consulting fees from Medtronic Inc. and Abbott Laboratories (SJM). Biotronik Inc. and Medtronic Inc. pay A.F. personal fees. Boston Scientific Inc., Medtronic Inc., and Abbott Laboratories have all provided H.A. research grants. NHLBI Grant RO1HL134674 has supported J.M.S. R.D.T. is funded by Medtronic for research, Theravance Biopharma for consulting, and Medtronic, Union Chimique Belge, and Novartis for lectures. Personal payments from Amarin, Boehringer Ingelheim, Sanofi Aventis, Respicardia, and Lundbeck were mentioned by B.O. There are no conflicts of interest declared by J.G.v.D., M.B., F.d.L., P.B.L., R.A.K., A.M., S.D.R., and V.R.