European Journal of General Medicine Medical Investigations Society ISSN: 1304-3897 Vol. 6, Num. 3, 2009, pp. 144-149

European Journal of General Medicine, Vol. 6, No. 3, July-September, 2009, pp. 144-149

Article

Heart rate fluctuations and late ventricular potentials in depression patients without clinical cardiovascular disease

Aydın Akyüz¹ , Salih Çolak¹ , M. Uğur Es² , Zeki Kılıçkap³

¹ Sivas Anatolia Hospital, Departmant of Cardiology, Sivas.
² Sivas Anatolia Hospital, Departmant of Cardiovasculer Surgery, Sivas
³ Sivas Numune Hospital, Departmant of Psychiatry, Sivas

Correspondence Address: MD. Aydın Akyüz Özel Sivas Anadolu Hastanesi
ayakyuz@mynet.com

Code Number: gm09032

Abstract

Keywords: Heart rate fluctuations, late ventricular potentials and depression

Introduction

There has been contradictory results about associa-tion between major depression and cardiovascular diseases. Further research is needed to determine how depression increases risk for cardiac morbidity and mortality ^[1],[2],[3]. Increased cardiovascular mortal-ity and morbidity in depression patients was demon-strated in several studies and depression was defined as an independent risk factor ^[4],[5],[6]. Various other studies in which depression was seen with decreased heart rate fluctuations were also reported ^[7],[8],[9], but some studies showed no difference between depres-sive and healthy individuals ^[10],[11].

It is said that these fluctuations indicating an increased sympathetic and decreased parasympathetic effect in depression patients are concurrent with arrhythmic events and increased mortality particu-larly in patients with a known organic heart dis-ease ^[8],[12]. However, there are no studies on late potential criteria and increase in the prevalence of arrhythmic events in untreated with antidepres-sant therapy depressive patients without an organic disorder. Therefore, we investigated parameters of heart rate fluctuations and late ventricular potentials changes in untreated with antidepressant therapy de-pressive patients without clinical cardiovascular dis-ease in this study.

Materials and Methods

Characteristics of the Patients and Control Groups

Patients were chosen from individuals who were not receiving any sorts of anti-depressants, but were diagnosed with depression by the psychiatry clin-ic and planned to begin drug treatment. Patients with hypertension, diabetes mellitus, coronary arte-rial disease, congestive heart failure, valvular heart disease, myocarditis, thyroid dysfunction, anemia, menstruation, chronic obstructive pulmonary disease were excluded from the study. Patients using drugs which might affect the autonomous system were also excluded from the study. Patients with previous ar-rhythmic event anamnesis were not included in the study. Consecutive 32 depression patients and 29 healthy individuals were included in the study. We recruited the healthy individuals according to physi-cal and physicologycal examination by medical doctor (cardiologist and psychiatrist).

Patients were aged between 32 and 64 (mean: 41 ± 14 years), and consisted of 18 male, 14 females. Healthy individuals were aged between 29 and 65 (mean: 39±15 years), consisting of 15 males, 14 females [Table - 1].

Diagnosis of Major Depression

Beck's depression inventory was used under the su-pervision of a psychiatrist in order to determine depression patients. Patients who received 17 points or more defined as depressive. Beck's depression in-ventory was developed to determine the depression risk and to measure the level and intensity of de-pressive signs ^[13]. This method is applicable both to psychiatric patients and healthy groups, and it has a self-assessment scale. It contains a total of 21 self -assessment sentences. Patients answer by marking on the scale and they fill out on their own. Each item is scored increasingly from 0 to 3, and the total score is obtained by adding these up. Total ranges in be-tween 0-63 ^[13] and the validity and security cutting point of the scale is accepted to be 17 ^[14].

Heart Rate Fluctuations and Analysis of the Late Ventricular Potentials

Cardioscan 12 channel, 10 wire digital holter re-corder was used to obtain 24-hour recordings of the patients outside the hospital. The signal averaged electrocardiogram (SAECG) program of this device was also used with its 3 channel(orthogonal lead), 7 wire recorder, and late potential analyses were per-formed. Recordings that lasted 23 hours ± 35 minutes were used for Holter analyses. Recordings lasting 35±5 minutes were used in a quite setting for late potential analyses. Heart rate fluctuations and late potential criteria were evaluated using a computer with Cardioscan software. SDNN (standard deviation of normal to normal intervals, 24-Hour normal values < 50 ms), SDNN index( average of the standard devia-tion of normal to normal intervals, 24-Hour normal values < 30 ms), SDANN (the standard deviation of the 5-minute average NN intervals, 24-Hour normal values < 40 ms), pNN50 (the percent of R to R in-tervals differing > 50 ms from the preceding one, 24-Hour normal values < 0.75%) and rMSSD (the root mean squared of successive differences, 24-Hour nor-mal values < 15) parameters were used for time-area parameter ^[15],[16].

Ectopic beats or beats originating from outside the sinus were excluded from these analyses. We did not recruit indivudials and patients having frequent atrial and ventricular ectopic beat (> 10 beat/hour) in both groups. Each heart beat was marked as normal or abnormal. Distances from one normal beat to the other were calculated. In practice, measurements can be performed as short measurements ranging from 5 minutes to 1 hour, in addition to 24-hour measure-ments. However the frequently used method is the one that is 24 hours long. Long and short RR interval fluctuations were measured in the time-area method. Measurements of the frequency-area method were performed by calculating Power Spectral Density. It is calculated from High frequency (HF), low fre-quency (LF), very low frequency (VLF) and the LF/HF rate. While HF represents parasympathetic power, VLF and LF determines sympathetic activation. There is significant correlation between frequency-area and time-area parametersn (HF and rMSSD and pNN50, LF and SDNN index, VLF and SDNN index, ULF and SDNN and SDANN) ^[15],[16].

Late potential criteria were carried out again using the software found in the same device. QRS waves were filtrated at 40-250 Hz bi-directionally in this device. Total period of filtrated QRS, the period of terminal QRS below 40mVs, and the root of the mean squared voltage of QRS in the final 40 ms were studied. Recordings with noise values above 0.7 microvolts were excluded from the study. SAECG is a noninvasive technique detecting the high-frequency, low-amplitude signals found at the end of the QRS complex and called late potentials. It is accepted that these signals are recorded from the slow con-duction sites of the ventricular myocardium and that these sites constitute a substrate for reentrant ven-tricular arrhythmias. As for criteria, duration of the filtrated QRS complex is significant if 1) longer than 114-120 ms 2) signals in the last 40 ms are below 20 microvolt (mV) 3) the period below 40mVs is longer than 38 ms ^[17], and the late potential is considered positive if 2 out of these 3 criteria are present.

Statistical Analysis

The unpaired t test was used in the comparison of the parametrical variables, and chi-square test was used when comparing the categorical variables of both groups. p< 0.05 was considered significant.

Results

There were no statistical differences between the two groups in terms of age and sex. [Table - 1]. However the rate of smoking and the level of educa-tion and body mass index was significantly higher in the group of patients with depression (p= 0.049, p=0.039, p= 0.020, respectively). Maximum, mean and minimum heart rate (beat/min) values were higher in the depression group. (p= 0.008; p= 0.002; p= 0.003, respectively) There were no statistical differ-ences between the two groups in terms of systolic and diastolic blood pressure (p= 0.197, p= 0.661 respectively).

There were no significant differences in the QT and QTc values between the two groups, respectively (p= 0.16; p= 0.14, respectively). While two of the time- area parameters, the SDNN and SDNN index, showed a significant decrease (p= 0.001) in the depression group compared with the control group, the oth-ers, i.e. rMSSD (p= 0.662) and pNN50 (p= 0.205), showed no significant changes. Although VLF, LF, LF/HF tended to increase and HF tended to decrease in the depression group, no statistical difference was found between VLF (p= 0.181) and LF (p= 0.290) and HF (p= 0.195) and LF/HF (p= 0.679) values, which are the frequency-area parameters. The sympathetic activity increase was higher in the depression group (p= 0.006), but there was also a parasympathetic activity decrease (p= 0.001) [Table - 2]. There were no statistical differences between the late potential values of both groups [Table - 3].

Discussion

Increased sympathetic activity is associated with in- creased corticotrophin response to stress ^[18],[19] .Cortisone's synergy with hypertriglyceridemia, hy-percholesterolemia and hypertension are known. There is also norepinephrine secretion in depression. Catecholamines increase the heart rate and blood pressure by increasing myocardial oxygen consump-tion. Serotonin also plays an important role in depres-sion. Its effects on increasing thrombocyte activation are known. Increase in thrombocyte aggregation was demonstrated in depression ^[20]. And also major de-pressive disorder is associated with decreased nitric oxide production ^[21] and elevated plasma IL-6 level,a good predictor of future risk for both cardiovascu-lar disease and osteoporosis ^[22].

Decreased heart rate fluctuation parameters mean a reduction in parasympathetic tonus and an increase in sympathetic tonus. It is known that major depressive diseases increase the prevalence of cardiovascular diseases ^[1],[2],[3]. Increased cardiovascular mortality and morbidity in depression patients was demonstrated in several studies and depression was defined as an in- dependent risk factor ^{[1],[2],[3],[4],[5]}. In certain studies, it was stated that HRF of depressives is not different from those of healthy individuals ^[10],[11]. Similar to the above mentioned studies ^[4],[5],[6], significant changes in the values of heart rate fluctuations were determined in our results. It has been determined in several studies that reduced heart rate fluctuations indicate a bad prognosis, particularly when seen concurrent with organic heart disorders ^[4],[5],[6].

High heart rate fluctuations occur in people with a healthy heart. Heart rate fluctuations are decreased in coronary heart diseases and congestive heart fail-ures ^[3]. The rate of smoking in our study group was seen with a higher prevalence than the control group. It is known that smoking is a positive risk factor for coronary heart disease and that it leads to an increase in sympathetic tonus. Its effects on heart rate fluctuations were not evaluated in this study. Besides, body mass indexes were also higher than those of the control group. Our study has some confounding factors above mentioned such as smoking and body mass index. There are no studies on late potential in untreated with antidepressant therapy depressive patients with-out an organic disorder ^[23]. Further studies are required on this issue. According to our results, the late ventriculer potential positivity is not present in our depression patients without any clinical cardio-vascular diseases. All patients with previous arrhyth-mic event anamnesis were excluded from this study. Thus, we did not consider depression to be a risk factor for arrhythmic events through this mechanism. However, some of the heart rate fluctiation param-eters were reduced. Consequently, we concluded that the use of heart rate fluctuation parameters useful in depression pa-tients without any clinical cardiovascular disease and not receiving any sorts of antidepressants in clinical practice. Whereas, the use of late potentials has no practical benefit.

References

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