Tag: ECG

Diagnostic value of 24-h ECG recording in Long COVID patients with postural orthostatic tachycardia syndrome

Abstract:

Background: Cardiovascular autonomic dysfunction (CVAD) is a major complication for a large proportion of Long COVID (LC) patients. The main phenotype of CVAD is postural orthostatic tachycardia syndrome (POTS), commonly observed as a sequalae of COVID infection, thus defining a subset of LC patients. POTS is a cardiovascular autonomic disorder characterized by an excessive heart rate (HR) increase and symptoms of orthostatic intolerance when assuming upright posture, occurring predominantly in young and middle-aged women. Since the start of COVID-19 pandemic it has been observed that up to 30% of patients with post-COVID-19 syndrome develop POTS with such symptoms as tachycardia, orthostatic intolerance, fatigue, and cognitive impairment. The heterogeneity of POTS symptoms makes the diagnosis and appropriate management of POTS more difficult and one of the first steps for clinicians is to develop and test relevant diagnostic methods for POTS.
Methods: Patients with persistent symptoms, 3 months after an acute SARS-CoV-2 infection were referred to the multi-disciplinary LC unit at a hospital in Sweden. Consecutive patients seen at this unit from 2021 to 2022 underwent a 24-h ECG recording. LC patients with POTS verified by active standing test and/or head-up tilt testing were prospectively enrolled in the study database and were compared with LC patients without POTS according to 3 specific analyses based on 24-h ECG recording : (1) cardiac autonomic activity expressed by heart rate variability, HRV (SDNN and RMSSD in ms) parameters, (2) awakening HR increase (HR mean 10 min before vs. 30 min after awakening) and (3) HR spikes (number/h if at least over than 30 bpm and at least during 30 s). Control group consisted of healthy subjects from 24-h ECG recordings database (HRV analysis) of a hospital in France. Data were expressed as mean (± standard deviation, SD) and frequencies (%).
Results: A total of 120 LC patients (mean age: 42.7 +/-9.97 y, 88% women) and 100 healthy subjects (mean age: 46.4 +/-10.2 y, 82% women) were included. LC with POTS (42%) was associated with (1) a decrease in most HRV parameters (mean SDNN: 86.8 +/-24.3 vs. 108.7 +/-24.1 ms, p=0.03), and the most reduced components were those related to the parasympathetic tone (mean RMSSD: 34,5 +/-20.4 vs. 45.6 +/-22.1 ms, p=0.04), (2) an abrupt and sustained increase in HR during the first 30 min after awakening (+30%, p<0.05) and (3) a higher number of HR spikes per h (1.4 +/-0.8 vs. 0.8 +/-0.7/h, p<0.001) compared with healthy subjects (HRV) and LC patients without POTS (awakenings and HR peaks) respectively.
Conclusion: A triple analysis of 24-h ECG recordings revealed presence of autonomic dysfunction in LC patients with POTS compared with those without POTS. This novel analysis may be introduced in the clinic for screening and therapy monitoring.

Source: D Hupin and others, Diagnostic value of 24-h ECG recording in Long COVID patients with postural orthostatic tachycardia syndrome, EP Europace, Volume 25, Issue Supplement_1, June 2023, euad122.626, https://doi.org/10.1093/europace/euad122.626 (Full text available as PDF file)

Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome

Abstract:

Patients with chronic fatigue syndrome (CFS) often complain of an inability to maintain activity levels and a variety of autonomic-like symptoms that make everyday activity intolerable at times. The purpose of the study was to determine if there were differences in vagal activity at fixed breathing rates in women with CFS.

Twelve women with the diagnosis of CFS between the ages of 32 and 59 years volunteered for the study. Healthy women, who were between the ages of 30 and 49, served as controls. Full signal electrocardiograph and respiratory signals were collected during a paced breathing protocol of three fixed breathing rates (8, 12 and 18 breaths/min) performed in the sitting and standing postures. Vagal activity was analyzed by means of heart rate spectral analysis to determine the subject’s response to specific breathing rates and postures. Heart rate variability was used as a non-invasive method of measuring the parasympathetic component of the autonomic nervous system.

Using this method, although there was significantly less vagal power in the sitting versus the standing postures for both groups, the overall vagal power was significantly lower (p < 0.034) in the CFS group versus healthy controls. Vagal power was also significantly lower (p < 0.01 to p < 0.05) at all breathing rates in both postures except while standing and breathing at 18 breaths/min. Knowledge of the differences in vagal activity for CFS patients may allow stratification for the analysis of other research variables.

 

Source: Sisto SA, Tapp W, Drastal S, Bergen M, DeMasi I, Cordero D, Natelson B. Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome. Clin Auton Res. 1995 Jun;5(3):139-43. http://www.ncbi.nlm.nih.gov/pubmed/7549414

 

Sympathetic overactivity in subjects complaining of unexplained fatigue

Abstract:

Theoretical and practical considerations suggest that in subjects complaining of fatigue, in the absence of evident organ dysfunction, an alteration in the autonomic nervous system might be present as a functional correlate.

Autoregressive spectral analysis of R-R interval variability from a surface ECG, was used in healthy control subjects (n = 24, age 45 +/- 4 years) and in subjects complaining of unexplained fatigue (n = 53, age 46 +/- 9 years) to obtain quantitative indices of the state of the sympathovagal balance, both at rest and during a mental stimulus (mental arithmetic), capable of enhancing sympathetic drive. Sympathetic and vagal modulations were inferred from the normalized powers of the low frequency and high frequency spectral components respectively.

We observed in patients, at rest, a prevailing low frequency component of R-R variability (patients low frequency = 73 +/- 11, control subjects 51 +/- 10 normalized units, P < 0.05). The responsiveness to mental arithmetic was reduced in patients as compared with controls. Systolic blood pressure variability did not differ. This suggested a selective imbalance in autonomic control of the sinoatrial node, characterized by sympathetic predominance as well as by vagal withdrawal, at rest.

The possibility of discriminating patients from control subjects on the basis of simple non-invasive functional markers might provide a better understanding of the mechanisms, clinical evolution and outcome of conditions such as the chronic fatigue syndrome, which lack ordinary evidence of disease, but comprise, as physiopathological correlate, a quantitative alteration of autonomic control.

 

Source: Pagani M, Lucini D, Mela GS, Langewitz W, Malliani A. Sympathetic overactivity in subjects complaining of unexplained fatigue. Clin Sci (Lond). 1994 Dec;87(6):655-61. http://www.ncbi.nlm.nih.gov/pubmed/7874856

 

Repetitively negative changing T waves at 24-h electrocardiographic monitors in patients with the chronic fatigue syndrome. Left ventricular dysfunction in a cohort

Abstract:

This study surveys the occurrence of repetitively negative to flat T waves, alternating with normal upright T waves in 24-h electrocardiographic recordings from a subspecialty infectious diseases outpatient practice during the years 1982 to 1990. Patients with normal resting electrocardiogram in the assayed leads, but with repetitively inverted to isoelectric abnormal T waves at Holter monitors, were considered to have abnormal readings.

A total of 300 patients had undergone a 24-h Holter monitor. This group included 24 individuals with chronic fatigue syndrome (CFS). This population was restricted to individuals 50 years old or younger, and the patients with CFS are compared with the patients without CFS.

One of the more striking differences between the two groups was the difference in abnormal Holter readings. The patients with CFS all had abnormal Holter readings, while 22.4 percent patients without CFS had abnormal readings (p < 0.01). We further report the occurrence of mild left ventricular dysfunction in 8 of 60 patients in continuing studies of this population with CFS, younger than 50 years old, and with no risk factors for coronary artery disease.

All 60 patients with CFS showed repetitively flat to inverted T waves alternating with normal T waves. Stress multiple gated acquisitions (MUGAs) (labeled erythrocytes with stannous pyrophosphate) were abnormal in eight patients with CFS. Although resting ejection fractions (EFs) were normal (mean, 60 percent), with increasing work loads (Kilopon meters [Kpms]), gross left ventricular dysfunction occurred. The fatigue of patients with CFS may be related to subtle cardiac dysfunction occurring at work loads common to ordinary living.

 

Source: Lerner AM, Lawrie C, Dworkin HS. Repetitively negative changing T waves at 24-h electrocardiographic monitors in patients with the chronic fatigue syndrome. Left ventricular dysfunction in a cohort. Chest. 1993 Nov;104(5):1417-21. http://www.ncbi.nlm.nih.gov/pubmed/8222798

 

Cardiac function at rest and with exercise in the chronic fatigue syndrome

Abstract:

To evaluate a possible cardiac pathophysiology of the chronic fatigue syndrome, we compared the resting cardiac function and exercise performance of 41 patients to those of an age-matched and sex-matched normal control group.

Persistent fatigue following an acute apparently viral illness was the major complaint of all patients; none had specific cardiac symptoms nor abnormal physical findings. Electrocardiographic spatial patterns were normal in the patients, and there were no differences in the body surface sum of positive T-wave integrals between the patients (240 microV.x 10(2) +/- 107 microV.s x10(2)) and control (244 microV.x 10(2) +/- 108 microV.s x 10(2) subjects. Twenty-four hour ambulatory ECGs revealed no differences in sinus rates and incidences of ventricular dysrhythmias in the two populations. Left ventricular dimensions and systolic fractional shortening values were also similar in both groups; moreover none of the patients had segmental wall motion abnormalities.

On graded exercise testing, 20 of 32 normal subjects achieved target (85 percent of age-maximum) heart rates, compared to four of 31 patients (p less than 0.001). The duration of exercise averaged 12 +/- 4 minutes for the normal subjects and 9+/- 4 minutes for the patients (p less than 0.01). The temporal profile of exercise heart rates was dissimilar in the two groups, with patients’ rates consistently and progressively less than those of normal subjects. Peak heart rate averaged 152 +/- 16 beats per minute for the normal group vs 124 +/- 19 beats per minute for the patients (p less than 0.0001); in age-related terms, respectively, 82 +/- 6 percent of the maximum heart rate vs 66 +/- 10 percent (p less than 0.0001).

Thus, patients with chronic fatigue syndrome have normal resting cardiac function but a markedly abbreviated exercise capacity characterized by slow acceleration of heart rate and fatigue of exercising muscles long before peak heart rate is achieved.

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Source: Montague TJ, Marrie TJ, Klassen GA, Bewick DJ, Horacek BM. Cardiac function at rest and with exercise in the chronic fatigue syndrome. Chest. 1989 Apr;95(4):779-84. http://www.ncbi.nlm.nih.gov/pubmed/2924607