Heart rate variability is a physiological feature indicating the influence of the autonomic nervous system on the heart rate. Association of the reduced heart rate variability due to myocardial ...infarction and the increased postinfarction mortality was first described more than thirty years ago. Many studies have unequivocally demonstrated that coronary artery bypass grafting surgery generally leads to significant reduction in heart rate variability, which is even more pronounced than after myocardial infarction. Pathophysiologically, however, the mechanisms of heart rate variability reduction associated with acute myocardial infarction and coronary artery bypass grafting are different. Generally, heart rate variability gradually recovers to the preoperative values within six months of the procedure. Unlike the reduced heart rate variability in patients having sustained myocardial infarction, a finding of reduced heart rate variability after coronary artery bypass surgery is not considered relevant in predicting mortality. Current knowledge about changes in heart rate variability in coronary patients and clinical relevance of such a finding in patients undergoing coronary artery bypass grafting are presented.
Abstract
Background
Heterophile antibodies are one of the most common causes of false-positive troponin.
Case summary
We report a case of a 53-year-old woman with false-positive troponin elevation ...and a clinical presentation understood and treated as non-ST-elevation acute coronary syndrome. Because of chronic basal elevation of troponin (at a ‘plateau’ level) and chest pain, the patient underwent several invasive coronary angiograms until false-positive increase of troponin due to heterophile antibodies was suspected. Borderline stenosis of a left circumflex coronary artery found on first coronary angiogram was a coincidental finding and heterophile antibodies in the patient’s serum were confirmed.
Discussion
This interesting case report aims to remind the clinicians about the possibility of false-positive troponin level due to laboratory analytical interference caused by heterophile antibodies. In this case, it is important to suspect false-positive troponin elevation, even when coronary artery disease is found. This rare and less mentioned and/or recognized cause of troponin elevation may lead to unnecessary invasive diagnostics and aggressive treatment of patients.
Aims
To assess the prevalence of left ventricular diastolic dysfunction in a population of patients with type 2 diabetes mellitus; to determine correlation of diastolic dysfunction with heart rate ...and its variability.
Methods
The study included 202 patients with type 2 diabetes mellitus. Echocardiography was performed with special reference to diastolic function, and heart rate variability was analysed using standard deviation of normal RR intervals, root mean square of successive differences and percentage of successive R–R intervals greater than 50 ms (pNN 50 %) in a 24-h electrocardiogram recording.
Results
Diastolic dysfunction is present in 79 % of type 2 diabetes mellitus patients: grade 1 in 52 %, grade 2 in 26 % and grade 3 in 1 % of patients. The subjects with grade 1 diastolic dysfunction had a statistically significantly higher heart rate variability compared with those with grade 2 diastolic dysfunction (LSD, post hoc test,
p
= 0.001). In the group with diastolic dysfunction, grade 2 reduced heart rate variability was recorded in 83 % of patients (37 and 7 % for grade 1 and normal diastolic function). An increase in the severity of diastolic dysfunction was associated with decreased heart rate variability and increased heart rate.
Conclusion
Progression of diastolic dysfunction is associated with a significantly greater prevalence of reduced heart rate variability, which is accompanied by increased heart rate.
Data regarding the autonomic control of heart rate in multiple sclerosis (MS) patients depending on the disease duration are lacking in the literature. The goal of this study was to evaluate ...differences in heart rate variability (HRV) in patients with MS according to the duration of the disease.
The study included 39 patients (23 female and 16 male; median age 42 years, range 34–53 years) with relapsing-remitting MS (RRMS) in stable phase and 39 age- and sex-matched healthy controls. RRMS patients were divided into two groups: group 1 with 21 patients within 5 years and group 2 with 18 patients with >5 years from the diagnosis of MS. HRV analysis was done with 24-h Holter ECG.
Patients with RRMS had a significantly lower overall HRV than controls: SDNN 91 ± 18 msec vs. 135 ± 24 msec,
p <0.001. RRMS patients with lower duration of disease (Group 1) had all higher HRV parameters except LF/HF ratio compared with RRMS patients with >5 years from the diagnosis of MS (Group 2): SDNN 94 ± 24 vs. 88 ± 21 msec,
p = 0.008; TP 2028 ± 1326 vs. 1683 ± 1017 ms
2,
p = 0.006.
Results of the study suggested that the autonomic control of heart rate depends on the disease duration in RRMS patients. Longer disease duration led to progressive impairment of cardiac autonomic balance in MS patients.
The goal of the study was to evaluate differences in heart rate variability (HRV) among post-myocardial infarction (MI) patients, depending on their participation in the Croatian war and on ...established diagnoses of post-traumatic stress disorder (PTSD).
The study included 34 male war veterans with diagnosed PTSD who had suffered a first MI and 34 age-matched post-MI patients without PTSD. Cardiac autonomic balance was evaluated through HRV analysis.
There were no differences in the mean R-R interval or overall HRV between the analyzed groups. Post-MI patients with PTSD had lower values for the square root of the mean of squared successive differences in R-R intervals (p = 0.02), the percentage of R-R intervals that were > or =50 milliseconds different from the previous interval (p = 0.03), and the high-frequency component (p = 0.03) but had higher values for the low-frequency component (p = 0.01) and the low-frequency/high-frequency ratio (p = 0.02), compared with post-MI patients without PTSD.
Post-MI patients with PTSD have higher sympathetic and lower parasympathetic heart rate modulation activity, compared with patients with MI and no PTSD.
Abstract The aim of study was to asses the heart rate variability (HRV) differences in 128 post-myocardial infarction (MI) patients based on initial treatment during acute phase of disease. The ...patients were divided into groups: group 1 patients who underwent primary PCI, group 2 patients who received fibrinolysis and group 3 patients who were treated conservatively. In comparison with groups 2 and 3, group 1 patients had all HRV analyzed parameters higher except for LF/HF ratio. The results of study suggest that patients who were treated by primary PCI had better preserved autonomic cardiac function compared with patients who received fibrinolysis or those who were treated conservatively in the acute phase of MI.
The level of autonomic dysbalance in the first months after acute ischemic cerebral stroke has not been thoroughly investigated, and the available data are uncomplete. The aim of this research is to ...establish the degree and dynamics of impaired cardiac autonomic balance recovery within the first six months following the acute ischemic cerebral stroke.
This prospective study included 78 patients who had suffered the first ischemic cerebral stroke and 78 sex and age-matched healthy subjects. We have analyzed heart rate variability (HRV) from a 24-hour Holter ECG. In the group of patients with ischemic cerebral stroke, HRV was measured after two and six months following the acute phase, respectively.
Two and six months after the acute ischemic cerebral stroke, all HRV variables, except low to high frequency ratio (LF/HF), were significantly lower in the group of stroke patients when compared to the control group. Furthermore, we found a significant increase in the overall HRV between months 2 and 6 after the acute phase of cerebral stroke; p = 0.03 for Standard deviation of all normal R-R intervals (SDNN) and p = 0.01 for Total power.
The results point to the gradual recovery of impaired cardiac autonomic balance in the patients with ischemic cerebral stroke within the first months following the acute phase. Nevertheless, HRV remains significantly lower even six months after the acute phase in comparison to healthy subjects.
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