1. Introduction
oronary artery disease is one of the most common cardiovascular disorders with a high mortality rate worldwide [1]. Research has shown that the incidence of coronary artery disease, including acute coronary syndrome, in Iran is the same as in developed countries. Today, this disease mostly develops before 45 in men and before the age of 50 in women [2]. This disease is the leading cause of death in Iran, accounting for 38% of deaths. According to research, 378 deaths occur due to heart disease in Iran every day [3, 4]. In Iran, the third leading cause of disability is ischemic heart disease [5]. However, mortality from cardiovascular diseases, including coronary heart disease, has decreased compared to the last 40 years due to improved surgical and diagnostic techniques [6]. The most critical and specific clinical symptoms of patients with acute coronary syndrome include sweating, shortness of breath, increased heart rate, blood pressure fluctuations, anxiety, suffocation, and imminent death [1].
There are different diagnostic methods for examining patients with cardiovascular problems. Coronary angiography is the choice method for confirming or rejecting coronary artery disease and gathering information to decide on the need for pharmacological treatment, angioplasty, or bypass surgery [7]. Angiography is a definitive and gold standard method for the diagnosis of coronary artery disease [8]. According to the latest data from the American Heart Association, one million patients in the United States undergo invasive and diagnostic heart tests annually. About 16000 to 18000 angiography cases are performed annually in Iran [9].
Cardiovascular angiography is a stressful procedure for patients. About 80% of patients reported anxiety before angiography. Also, 50% of patients reported fear and anxiety caused by angiography as more distressing than chest pain [10]. Anxiety is important for these patients because they already have elevated blood catecholamines, adrenocortical hormones, prolactin, and cortisol. Also, anxiety increases their respiration rate, heart rate, cardiac output, and blood pressure. Anxiety can also increase the myocardium’s need for oxygen before and during angiography, leading to ischemic pain and irregular heart rhythms. As a result of this process, more pressure is applied to the heart that will cause angiography disorders and difficulty in definitive diagnosis [11, 12].
Pharmacological and non-pharmacological methods can be used to alleviate anxiety. Despite the therapeutic effects of drugs, because of their side effects, the use of pharmaceutical methods is less considered by patients today. Various non-pharmacological methods are used as adjunctive and even alternative therapies because of the lack of side effects and risks [1]. Numerous studies have been conducted in the country and abroad in using non-pharmacological methods to influence various variables in angiography, such as pain, overt and covert anxiety, physiological indicators, and angiographic results. Each of these studies reported the benefits and effects of non-pharmacological methods. Hasavari et al. reported in their research that foot reflexology massage is a safe nursing intervention. It is useful, applicable, and cost-effective in reducing the anxiety of angiography candidates [13]. 
Abdi Joybari et al. reported that non-pharmacological interventions such as aromatherapy inhalation with orange essential oil reduce the overt anxiety of patients undergoing coronary angiography [14]. Pourmoohd et al. reported in their research that music could reduce the level of anxiety in patients before angiography, and this non-pharmacological method could be used as an easy and low-cost method [15]. Mansourzadeh et al. reported in their study that acupressure had a positive effect on reducing anxiety before angiography [16].
One of the non-pharmacological and non-invasive interventions is distraction. It may occur through the senses of sight, hearing, touch, movement, and imagination. Various methods such as music, study, games, sports, cartoons, jokes, meeting relatives and family, and doing some daily activities such as painting and sewing and rhythmic breathing are some of these methods [17]. 
Rhythmic breathing is one of the distraction methods and is a solution to increase the oxygen uptake available in cardiovascular patients [18]. Rhythmic breathing is simple, inexpensive, and patients have welcomed the non-invasive method and reduce pain. Rhythmic breathing comes in many forms, including hey ho, looking at an object and counting the numbers 2, 3, and 4 during the inhale and exhale, blowing with a straw into a glass full of water, and breathing slowly with a regular rhythm [19]. Performing this method of treatment by the nurse as the person who is most available to the patient and also as a person who has a professional and caring role in this field will help to operationalize the role of nurses in assisting patients in improving their condition through non-pharmacological methods [20]. 
Studies have been conducted in Iran and abroad on the effect of the respiratory technique on various dependent variables such as pain and anxiety. This effect indicates the positive impact of this non-pharmacological and non-invasive method on these variables. Borzo et al. aimed to determine the effect of rhythmic breathing on pain intensity and analgesia received by patients after orthopedic surgery. They reported that rhythmic breathing as a non-pharmacological and non-invasive method could reduce the pain and number of analgesics patients received after orthopedic surgery [21]. Seraji and Vakilian concluded that breathing technique reduces labor pain, and these alternative methods could be used instead of drugs associated with side effects [22]. Farzin-Ara also showed in his research that rhythmic breathing reduces pain after orthopedic surgery [23].
Another non-pharmacological and non-invasive method recently used in medicine is the use of virtual reality (VR). The term virtual reality, which was introduced almost two decades ago, is an entirely new term in the health industry. Its use has developed significantly in recent years and will undoubtedly become part of everyday life vocabulary. Virtual reality is a new technology that, in a graphical environment, the user not only feels a physical presence in the virtual world but can also interact constructively with that environment. This technology delivers extremely high-quality 3D images on its screen [24]. 
The results of the research show that virtual reality as a new tool, on the one hand, is used in various types of rehabilitation, neuroscience therapies, mental disorders to treat pain, stress, fear, and common anxiety. On the other hand, it has received a lot of attention in modern medical education, such as surgery education. Therefore it can find its place in medicine, psychiatry, and other fields [24]. In healthcare, virtual reality techniques have a wide range of applications from diagnosis, treatment, counseling, and rehabilitation to hospital design [25]. 
Ali Akbari, in his research, concluded that virtual reality technology could play an effective role in improving and reducing psychological symptoms, especially stress [24]. Researchers also compared relaxation techniques with virtual reality technology and traditional relaxation techniques in people with anxiety. The results show that the relaxation method combined with virtual reality technology has more positive effects on reducing anxiety, mood, and ultimately better life quality [26]. Management of anxiety, control of nausea and vomiting in chemotherapy, control of pain in burns, treatment of fears, and rehabilitation of patients with brain injury are some of the benefits of using virtual reality for patients [27]. Virtual reality technology is pain-free and non-invasive. By creating a distraction, it can be used indefinitely and without the need for re-costing and does not require much training of personnel; besides, its cost is less than methods such as hypnosis and medication [28].
Coronary angiography causes a lot of anxiety for the patient [29, 30], which, in some cases, leads to the patient refusing to perform this procedure [31]. Bagheri et al. also reported in their research that anxiety has a direct and positive role in the recurrence of heart attack [32]. The effects of anxiety on angiography patients, before and during the procedure, are significant. It can lead to ischemic pain and arrhythmias and ultimately disrupts the patient’s diagnostic and therapeutic process. Also, anxiety causes more discomfort for patients compared to chest pain. There is no specific action for patients’ anxiety before the procedure, so the implementation of this study is necessary. Besides, there are few studies by the researcher on the application of virtual reality as a new medical technology and breathing technique, and none of them in the field of nursing care have studied the effects of rhythmic breathing and virtual reality on anxiety at the same time. Therefore, the present study was conducted to compare virtual reality and rhythmic respiration on anxiety in patients undergoing coronary angiography in Ali Ibn Abitaleb Hospital in Zahedan City in 2019.
2. Materials and Methods
This study is a randomized, single-blind clinical trial. We performed a comparative analysis of rhythmic breathing and virtual reality on the anxiety of patients undergoing coronary angiography at Ali Ibn Abitaleb Hospital in Zahedan City in 2019. Research samples were selected in two stages. First, angiography candidates admitted to CCU and PCCU were selected by the available sampling method. Using color cards, we randomly assigned patients into three groups of rhythmic breathing, virtual reality, and control. The sample size was calculated based on Majidi et al. study [29] with a 95% confidence level, 90% statistical power. Using the sample size formula to compare the means due to the three groups of the study, we multiplied the number by 1.4, which was obtained as 20 people for each group. To ensure the sample size’s adequacy, we selected 30 people in each group and a total of 90 people as a sample size.
The inclusion criteria included stability of hemodynamic status (no cardiac dysrhythmia, arterial blood oxygen saturation more than 80%), being 25 to 60 years old, alertness, first-time coronary angiography, no hearing or vision impairment, no mental disorders, non-drug addiction, no hypothyroidism, and no respiratory problems. The intervention in the virtual reality and rhythmic breathing groups was performed so that candidates for angiography were studied before entering the angiography room. 
First, the patient completed the demographic and disease information form. The patient also completed the level of overt anxiety with the Spielberger State-Trait Anxiety Inventory (STAI). In cases that the patient was illiterate or unable to complete the inventory, the questionnaire was completed by asking the patient and by an uninformed researcher of the intervention technique. The intervention was performed about an hour before the patient entered the angiography room. In the rhythmic breathing group, the breathing technique was explained to each patient. The breathing technique was Sukha Pranayama. The patients were asked to sit in a chair and fully relax their bodies, then closed their eyes and asked to think of nothing but the process of breathing. We asked the patient to inhale and exhale regularly and slowly through the nostrils and consciously use all parts of the lungs (top, middle, and base) during Sukha Pranayama exercises. They inhale energy into their lungs and expel stress in exhale. During the intervention, we tried to control the participants’ breathing by providing verbal instructions. The inhalation and exhalation phase each lasted 5 seconds, a total of 10 seconds of the respiratory cycle. The number of breaths was 6 breaths per minute. This breathing technique was performed for 5 consecutive minutes [33].
In the virtual reality group, the intervention consisted of showing calming images for patients using a virtual reality camera for 5 minutes [28]. The patient’s anxiety level was measured pre-intervention, half an hour, and one hour after the intervention. The patients in the control group received routine care before angiography, and their anxiety was measured. The information was collected in a two-part form prepared by the researcher (responsible author) with the help of a researcher unaware of the intervention techniques. This form consisted of demographic and disease information and STAI. 
The demographic and disease information form included 5 items of age, marital status, education, ethnicity, and underlying disease. The STAI includes separate self-assessment scales to measure state anxiety. This scale contains 20 expressions scored on a 4-point Likert scale (very low/low/high/very high). Each of these expressions is assigned a score between 1 and 4. A score of 4 indicates a high level of anxiety, which includes 10 phrases on this scale (3, 4, 6, 7, 9, 12, 13, 14, 17, 18) and 10 other phrases to score (1, 2, 5, 8, 10, 11, 15, 16, 19, 20), a high rating for each phrase indicates no anxiety. The range of scores is between 20 and 80. Higher scores indicate more anxiety of the person completing the questionnaire. 
STAI is a standard questionnaire that has been used in many studies in Iran and abroad to measure the severity of anxiety [34]. In 1993, Mehram conducted a study to standardize the Spielberger test, the reliability of which was declared as 0.9 based on the Cronbach alpha for the norm group on the state anxiety scale, and this rate was 0.94 in the criterion group [35]. Rabiee et al. and Rouhi et al., in the preliminary study, calculated the reliability of the Spielberger test as 89% and 90%, respectively [36, 37]. 
In the present study, the confirmation of reliability was measured by the internal consistency method. So that during the preliminary studies, this tool was completed on 20 people at a time, and then their reliability was calculated using the Cronbach alpha (α=0.92). The collected data were entered into SPSS version 16. Descriptive statistics were used to describe the obtained data. The mean of quantitative variables was evaluated in the study groups by repeated measures analysis of variance. The paired t test was used to assess the mean of quantitative variables before and after the intervention in groups. Analysis of variance was used for quantitative variables, and Chi-square (X2) test was used for qualitative variables to investigate the uniformity of contextual variables in the groups. The level of significance in the present study was considered less than 0.05.
3. Results 
In this study, the number of patients for each group was considered 30, which did not decrease until the end of the research. Finally, the research and data analysis was performed on 90 patients. The Shapiro-Wilk test results showed that the research data have a normal distribution, so parametric tests were used to analyze the data. The Shapiro-Wilk results are reported for the normality of anxiety-related data (Statistic=0.48, P=0.09, df=90). An equality test of variance was also performed, and the results showed equality of variance (df=2, P=0.12, Levene’s statistic=0.005). To use the analysis of variance test, the repeated measures of the test assumptions such as the qualitative nature of the independent variable, the equivalence of the variance of the sum of the subjects’ scores, and homogeneity of variances should be established. Based on Mauchly’s test of sphericity, the assumption of the equality of variances within the subjects has been observed (P=0.39).
Results of this study showed that patients in the three groups are homogeneous in terms of demographic characteristics so that the mean±SD age of the virtual reality group was 49.96±8.10 years, of the rhythmic breathing 50.56±8.16 years, and the control group 51.36±8.11 years (Table 1).


Mean±SD scores of patients’ anxiety in the virtual reality group in the pre-intervention, half an hour, and one hour after the intervention were 57.56±7.82, 41.10±7.17, and 42.30±7.46, respectively. As can be seen, this mean was lower than half an hour and one hour after the intervention compared to the pre-intervention. The mean±SD scores of patients’ anxiety in the rhythmic breathing group before the intervention, half an hour, and one hour after the intervention were 57.10±6.49, 47.63±5.49, and 47.46±6.14, respectively. As can be seen, these scores were lower than half an hour and one hour after the intervention compared to the pre-intervention. But in the control group, the mean±SD scores of anxiety scores in the pre-intervention, half an hour, and one hour after the intervention were 56.33±6.74, 55.80±6.41, and 55.93±6.47, respectively. 
There was no change in the different measurement time points (Table 2).


The results showed a significant interaction between time and group, meaning that the pattern of changes in the mean score of patients’ anxieties in three measurement points from before the intervention to one hour after the intervention was different between the three groups of virtual reality, rhythmic breathing, and control (P=0.001). At the moment of pre-intervention, none of the groups were significantly different from each other. Half an hour later, all three groups were significantly different from each other, meaning that the virtual reality group and the rhythmic breathing group were significantly different from the control group. The virtual reality group was significantly different from the rhythmic breathing group (P=0.001). 
About one hour after the intervention, all three groups were significantly different from each other, meaning that the virtual reality group and rhythmic breathing group were significantly different from the control group (P=0.001), and the virtual reality group was significantly different from the rhythmic breathing group (P=0.011). In the virtual reality group, pairwise comparisons showed that the mean score of anxiety at times 1 to 2 (P=0.001), 1 to 3 (P=0.001), and 2 to 3 (P=0.02) were significantly different from each other. In the control group, pairwise comparisons showed that the mean score of anxiety in any of the three measurement time points was not significantly different from each other (P=1) (Table 3). 


4. Discussion
This study aimed to compare the effect of virtual reality and rhythmic breathing on anxiety in patients undergoing coronary angiography in Ali Ibn Abitaleb Hospital in Zahedan City in 2019. Because of the high prevalence of cardiovascular diseases, new diagnostic and therapeutic methods have been developed to reduce the mortality of these diseases. Studies show that the mortality rate following cardiovascular diseases has been reduced by 50% using new diagnostic and treatment methods [9]. However, these methods cause problems such as anxiety. The results of the present study showed that the mean score of overt anxiety of angiography candidate patients in all three groups in the pre-intervention was moderate. 
Jamshidi also reported that most of the studied samples had moderate overt anxiety [9]. Tel et al. also showed that patients who are candidates for angiography have moderate to severe degrees of anxiety before angiography [38]. Because of the high percentage of this rate and the effect of anxiety on the patient’s performance, special attention should be paid to this issue and consider appropriate strategies to reduce anxiety. In most cases, the use of aggressive methods leads to a degree of anxiety tolerance by the patient. Stress leads to an increase in physiological factors in the body and thus puts the cardiovascular system at risk [39]. If these changes occur during cardiac catheterization, they can cause cardiac dysrhythmias and coronary artery spasm [40].
 Because of the concerns over anxiety before angiography and the benefit of virtual reality and rhythmic breathing, studies have been conducted in the country and abroad on various dependent variables such as pain and anxiety. The results indicate the positive effect of these non-pharmacological and non-invasive methods on these variables. The results showed that reducing the mean anxiety of the research samples during the intervention in the virtual reality and rhythmic breathing group was significantly more than the control group. Morris Linzette et al. showed that virtual reality had a positive effect on anxiety [41]. In a study aimed at determining the impact of video information on angiography patients’ anxiety, Jamshidi et al. reported that training using video technology could improve the outcome of angiography and patients’ anxiety [8]. Fuji et al. also reported that guided visualization effectively reduces anxiety in patients undergoing coronary angiography [42]. Mohammadi et al. also reported that group training effectively reduces patients’ overt anxiety. Abdi Joybari et al., in a study, showed that aromatherapy with orange is effective in reducing the overt anxiety of angiography candidates [14]. These results are consistent with the results of the present study. Borzo et al. aimed to determine the effect of rhythmic breathing on pain intensity and analgesia received by patients after orthopedic surgery reported that rhythmic breathing as a non-pharmacological and non-invasive method could reduce pain and the number of analgesics received by patients after orthopedic surgery [21]. Seraji and Vakilian concluded that breathing technique reduces labor pain, and these alternative methods can be used instead of drugs associated with side effects [22]. Farzin Ara also showed in his research that rhythmic breathing leads to a reduction in pain after orthopedic surgery [23]. 
The results of the present study also showed that rhythmic breathing and virtual reality as methods of distraction are effective to reduce the overt anxiety of angiography patients. Nurses working in cardiac care departments can use these easy, low-cost, and uncomplicated methods to reduce anxiety before angiography, depending on environmental conditions and facilities.
5. Conclusion
The results of the present study showed that the use of virtual reality and rhythmic breathing techniques as non-invasive, low cost, uncomplicated, and easy to implement methods is effective in reducing the overt anxiety of angiography candidates. Considering the importance of anxiety and its effects on the angiographic outcome, using these methods is recommended to nurses working in cardiac care departments to reduce patients’ anxiety before coronary angiography.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles are considered in this article. The participants were informed of the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information and were free to leave the study whenever they wished, and if desired, the research results would be available to them. The Ethics Committee of Zahedan University of Medical Sciences and the National Committee for Ethics in Biomedical Research approved the study (Code: IRZAUMS.REC.1397.435). The research also has been registered in the International Center for Clinical Trials of Iran (IRCT20150106020581N3). 

Funding
This research was extracted from the MA. thesis of Faezeh Pouryousef at Critical Care Nursing in Nursing & Midwifery School approved by the Ethics Committee of Zahedan University of Medical Sciences (No: 9184). The study was supported financially by the Vice-Chancellor for Research.

Authors' contributions
Conceptualization and supervision: Fariba Yaghoubinia, Faezeh Puryousef; Methodology: Ali Navidian, Omid Rafizadeh; Investigation, writing – original draft, and writing – review & editing: All authors; Data collection: Faezeh Puryousef; Data analysis: Fariba Yaghoubinia; Funding acquisition and resources: Fariba Yaghoubinia, Ali Navidian.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors express their gratitude to the Vice-Chancellor for Research of Zahedan University of Medical Sciences. We also appreciated the officials and the staff of Ali Ibn Abi Taleb Hospital and the patients.


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