Supraventricular Tachycardia Associated With Repeat Cesarean Section Under Spinal Anesthesia

Supraventricular tachycardia (SVT) is the most common tachyarrhythmia of pregnancy. Catecholamine surges, the use of vasoactive agents during delivery, and increased cardiac output during pregnancy are the most common contributing factors to developing SVT. SVT is usually benign in presentation but can lead to more serious arrhythmias in patients with a history of mitral stenosis secondary to rheumatic heart disease. When an SVT is detected, organic heart causes should be ruled out first. Symptoms of SVT include shortness of breath, palpitations, syncope, sweating, chest pain, and dizziness. In patients who are refractory to pharmacologic management and hemodynamically unstable, electrical cardioversion has proven to be efficacious and safe in all trimesters. The initial treatment for hemodynamically stable patients is to attempt vagal maneuvers, such as carotid sinus massage or Valsalva maneuver. If the SVT does not convert to normal sinus rhythm, treatment with adenosine or beta-blockers may be initiated. Treatment with atenolol and verapamil should be avoided due to their teratogenic effects.

Tests for the identification of reflex syncope mechanism

INTRODUCTION

Treatment efficacy of reflex syncope is mainly related to the mechanism underlying syncope rather than its etiology or clinical presentation. The predominant mechanism underlying reflex syncope can be assigned to hypotensive or to bradycardic phenotypes.

AREAS COVERED

Methodology and diagnostic criteria of the most useful tests for the identification of hypotensive and bradycardic phenotypes are discussed. Diagnostic tests for the hypotensive phenotype include office blood pressure measurement with active standing test, home, and wearable blood pressure monitoring, 24-h ambulatory blood pressure monitoring and tilt table test. Diagnostic tests for the bradycardic phenotype include carotid sinus massage, tilt table test and prolonged ECG monitoring.

EXPERT OPINION

In reflex syncope, the documentation of bradycardia/asystole during a syncopal episode does not rule out the possibility that a preceding or parallel hypotensive reflex plays an important role. Similarly, even when a hypotensive mechanism is established, the possibility of an associated cardioinhibitory reflex should be investigated. Investigating the mechanism of reflex syncope is mandatory in patients with severe recurrent episodes, with the final aim to develop a personalized treatment strategy. Recent trials have demonstrated the benefits of personalized mechanism-based therapy, thus highlighting the importance of a comprehensive assessment of the mechanisms underlying syncope.

Bedside Carotid Sinus Massage for Syncope Evaluation With Bifascicular Block and First-Degree Atrioventricular Block

Symptomatic bifascicular block (BFB) with a reversible high-grade atrioventricular block (AVB) is an overlooked cause of syncope with differing diagnostic and therapeutic approaches. We present a case of a 79-year-old gentleman with multiple episodes of cardiac syncope. Initial electrocardiogram revealed a left bundle branch block and first-degree AVB worsened by bedside carotid sinus massage (CSM) obviating the need for electrophysiologic (EP) studies or continuous electrocardiographic monitoring for further evaluation. This case highlights the importance of CSM as a useful clinical tool in addition to EP studies and internal loop recorder (ILR) placement for assessment and appropriateness of permanent pacemaker (PPM) implantation. It also sheds light on the differing management protocols between EP studies and ILR evaluation versus empiric PPM implantation for patients with cardiac syncope secondary to BFB and AVB.

Comparison of Various Vagal Maneuvers for Supraventricular Tachycardia by Network Meta-Analysis

BACKGROUND

Vagal maneuvers (VagMs) are recommended as the first-line treatment of supraventricular tachycardia (SVT). However, the optimal type of VagMs remains unproven.

AIM

This study aims to compare the effectiveness and adverse events amongst VagMs on SVT via network meta-analyses (NMAs).

METHODS

We systematically searched randomized controlled trials (RCTs) that involved adults with SVT and compared VagMs without language restrictions. We determined the initial and final responses of conversion rate to sinus rhythm and adverse events. Risk of bias (RoB) was appraised by Cochrane revised tool, and contribution matrix was calculated. NMAs were synthesized using frequentist random-effects model and presented as relative risk (RR) with 95% CI. The order of probability was presented as surface under the cumulative ranking curve analysis (SUCRA). Sensitivity analysis was performed using both Bayesian and frequentist approach with fixed- or random-effects models. Certainty of evidence (CoE) was rated by using the Grading of Recommendations, Assessment, Development, and Evaluations methodology.

RESULTS

Fourteen RCTs with 2,180 patients were enrolled. Small portion of mixed estimates was contributed from high overall RoB studies. Compared with carotid sinus massage (CSM), the modified Valsalva maneuver (MVM) was the most effective VagM after initial performance [SUCRA: 0.9992, RR: 5.47 (1.77-16.93)] and at the end of study [SUCRA: 1.0000, RR: 3.62 (2.04-6.39), CoE: high]. The standard VM did not elicit better conversion rate to the sinus rhythm than CSM at the initial response [SUCRA: 0.4395, RR: 1.97 (0.63-6.15)] and at the end of the study [SUCRA: 0.4795, RR: 1.64 (0.94-2.87), CoE: moderate]. The SUCRA value of CSM at the initial and final responses was the least one amongst three VagMs (0.0613 and 0.0205, respectively). Adverse events amongst three VagMs were similar (CoE: low). Sensitivity analyses yielded consistent results.

CONCLUSION

We recommended MVM as the first choice of VagM for rhythm conversion before the pharmacological management of SVT.

Reproducibility of carotid sinus massage

AIMS

The reproducibility of carotid sinus massage (CSM) is debated. The aim of this study was to assess the reproducibility according to the methodology and diagnostic criteria defined by the guidelines on syncope of the European Society of Cardiology.

METHOD

Among 2800 patients with syncope who underwent CSM in the years 2005-2019, 109 patients (62 males; mean age 76 ± 10 years) had performed a second CSM after a median of 28 months. Carotid sinus hypersensitivity (CSH) was diagnosed when CSM elicited a pause of >3 s and/or a fall in systolic blood pressure >50 mm Hg without reproduction of spontaneous symptoms. Carotid sinus syndrome (CSS) was established when spontaneous symptoms were reproduced in the presence of bradycardia and/or hypotension.

RESULTS

The reproducibility of CSM was 78% for 18 CSS patients, 41% for 29 CSH patients, and 77% for 62 negative patients. The corresponding interrater agreement was good for CSS (kappa = 0.66), moderate for negative CSM (kappa = 0.42), and poor for CSH (kappa = 0.30). Combining CSH and negative tests, their reproducibility rose to 90% with kappa = 0.66.

CONCLUSION

CSS but not CSH has a good reproducibility. About half of patients with CSH had a negative response at the second test, thus suggesting a great overlap between them.

Initial and Sustained Response Effects of 3 Vagal Maneuvers in Supraventricular Tachycardia: A Randomized, Clinical Trial. J Emerg Med. 2019;57:299-305. [PMID: 31443919 DOI: 10.1016/j.jemermed.2019.06.008]

BACKGROUND

For acute termination of supraventricular tachycardia (SVT), vagal maneuvers, including the standard Valsalva maneuver (sVM), modified Valsalva (mVM) maneuver, and carotid sinus massage (CSM), are first-line interventions. There is no criterion standard technique.

OBJECTIVE

This prospective, randomized study was aimed at analyzing the success rates of these 3 vagal maneuvers as measured by sustaining sinus rhythm at the fifth minute and SVT termination.

METHODS

We conducted this prospective, randomized controlled study in an emergency department (ED). We enrolled all the patients who were admitted to the ED and diagnosed with SVT. We randomly assigned them to 3 groups receiving sVM, mVM, and CSM and recorded the patients' responses to the vagal maneuvers and SVT recurrence after vagal maneuvers.

RESULTS

The study was completed with 98 patients. A total of 25 (25.5%) instances of SVT were initially treated successfully with vagal maneuvers. The success rate was 43.7% (14/32 cases) from mVM, 24.2% (8/33) for sVM, and 9.1 % (3/33) for CSM (p < 0.05). At the end of the fifth minute, only 12.2% (12/98) of all patients had sinus rhythm. Sinus rhythm persisted in 28.1% (9/32) of patients in the mVM group, 6.1% (2/33) of patients in the sVM group, and 3% (1/33) in the CSM group at the fifth minute (p < 0.05).

CONCLUSION

mVM is superior to the CSM maneuver in terminating SVT and maintaining rhythm. We conclude that it is beneficial to use mVM, which is more effective and lacks side effects.

The accuracy of anatomical landmarks for locating the carotid sinus

BACKGROUND

carotid sinus massage (CSM) is a valuable clinical test for carotid sinus syndrome (CSS) and relies on accurately locating the carotid sinus (CS).

OBJECTIVE

in this study, we sought to examine the accuracy of using anatomical landmarks for locating the CS.

METHODS

consecutive patients (n = 20) were recruited prospectively. Two clinicians, trained in CSM, were asked to locate the CS using anatomical landmarks. A point on the skin overlying the CS was then marked by a vascular technician using ultrasound. Accuracy of techniques was compared using intra-class correlation coefficients and Bland-Altman statistics.

RESULTS

anatomical landmarks underestimated the CS location by 1.5 ± 1.3 cm. Error extremes ranged from 4 cm below to 2 cm above CS using anatomical landmarks. A moderate correlation between ultrasound and anatomical landmarks was found, r = 0.371 (P = 0.031).

CONCLUSION

this is the first study to characterise the accuracy of standard anatomical landmarks used in CSM. Results suggest that the point of maximal pulsation has the lowest associated error. Future work should examine CSM yield across this and a range of other methodological factors.

Carotid sinus syndrome: Progress in understanding and management

Carotid sinus syndrome (CSS) is a disease of the autonomic nervous system presenting with syncope, especially in older males who often have cardiovascular disease. The aetiology is unknown and epidemiological data is limited. Forty new patients/million population have been estimated to require pacing for CSS and these patients represent ∼9% of those presenting syncope to a specialist facility. CSS is defined as a response to carotid sinus massage (CSM) that includes reproduction of spontaneous symptoms. Cardioinhibitory CSS shows 3s asystole on CSM and vasodepressor CSS shows >50 mmHg fall in blood pressure (BP), there are mixed forms. The methodology of CSM requires correct massage in the supine and upright with continuous ECG and BP. Assessment of the vasodepressor component implies the ‘method of symptoms’ using atropine to prevent asystole. Carotid sinus hypersensitivity (CSH) is a related condition where CSM is positive in an asymptomatic patient. CSH cannot be assumed to respond to pacing. CSS patients present syncope with little or no warning. If no cause is revealed by the initial evaluation, CSM should be considered in all patients >40 years. CSM carries a small risk of thromboembolism. Therapy for cardioinhibitory CSS is dual chamber pacing, which is most effective in patients with a negative tilt test. Syncope recurrence is ∼20% in 5 years in paced patients. Therapy for the vasodepressor component of CSS, as pure vasodepression or mixed, where tilt testing will likely be positive, is often unrewarding: alternative therapeutic measures may be needed including discontinuation/reduction of hypotensive drugs.

Neuroautonomic evaluation of patients with unexplained syncope: incidence of complex neurally mediated diagnoses in the elderly

Background

The incidence of syncope increases in individuals over the age of 70 years, but data about this condition in the elderly are limited. Little is known about tilt testing (TT), carotid sinus massage (CSM), or supine and upright blood pressure measurement related to age or about patients with complex diagnoses, for example, those with a double diagnosis, ie, positivity in two of these three tests.

Methods

A total of 873 consecutive patients of mean age 66.5±18 years underwent TT, CSM, and blood pressure measurement in the supine and upright positions according to the European Society of Cardiology guidelines on syncope.1 Neuroautonomic evaluation was performed if the first-line evaluation (clinical history, physical examination, electrocardiogram) was suggestive of neurally mediated syncope, or if the first-line evaluation was suggestive of cardiac syncope but this diagnosis was excluded after specific diagnostic tests according to European Society of Cardiology guidelines on syncope, or if certain or suspected diagnostic criteria were not present after the first-line evaluation.

Results

A diagnosis was reached in 64.3% of cases. TT was diagnostic in 50.4% of cases, CSM was diagnostic in 11.8% of cases, and orthostatic hypotension was present in 19.9% of cases. Predictors of a positive tilt test were prodromal symptoms and typical situational syncope. Increased age and a pathologic electrocardiogram were predictors of carotid sinus syndrome. Varicose veins and alpha-receptor blockers, nitrates, and benzodiazepines were associated with orthostatic hypotension. Twenty-three percent of the patients had a complex diagnosis. The most frequent association was between vasovagal syncope and orthostatic hypotension (15.8%); 42.9% of patients aged 80 years or older had a complex diagnosis, for which age was the strongest predictor.

Conclusion

Neuroautonomic evaluation is useful in older patients with unexplained syncope after the initial evaluation. A complex neurally mediated diagnosis is frequent in older people. Our results suggest that complete neuroautonomic evaluation should be done particularly in older patients.