A High performance electronic nose system for the recognition of myocardial infarction and coronary artery diseases

https://doi.org/10.1016/j.bspc.2020.102247Get rights and content

Highlights

  • An electronic nose has been made and the breaths of cardiovascular diseases patients were analyzed.

  • The MI patients were separated from the healthy subjects and SCAD patients with a classification accuracy rate of 97.19%.

  • The SCAD patients were separated from the healthy control subjects with a classification accuracy performance of 81.48%.

  • The proposed study could be a guide study in the field of diagnosis of cardiology diseases by using electronic nose.

Abstract

Electronic noses are devices that detect the number and level of chemicals in an odor. This is accomplished by means of chemical gas sensors in the device’s structure. The device recognizes the odors that were introduced to it via the software. When we breathe air, several gas exchanges take place in our lungs (e.g., O2-CO2 at the alveola-capillary level). Some gases in our blood are presented with our breath. The detection of these gases can provide information about our health. Nowadays, many diseases can be diagnosed with very high accuracy by using an electronic nose. Despite advances in diagnoses and treatments, cardiovascular disease is still the leading cause of mortality worldwide. Coronary artery disease is the leading cause of cardiovascular mortality and morbidity. The ability to diagnose coronary artery disease from the breath will accelerate the diagnosis, and thus, the initiation of treatment, which may save many lives. This study, involved an investigation of whether or not diseases (e.g., myocardial infarction, stable coronary artery disease) can be diagnosed from exhaled respiratory air using an electronic nose. This involved collecting data on exhaled breath from 33 patients diagnosed with myocardial infarction that underwent a primary percutaneous coronary intervention, 22 patients with stable coronary artery disease and 26 patients without heart disease. An electronic nose containing 19 gas sensors was manufactured for this study. The respondents’ breath was collected in a sterile manner. The statistical features including mean, skewness, kurtosis and derivative variance were extracted from the breath samples. These features were classified for the entire database using the support vector machine classifier by selecting 66 % as a training set and 34 % as a test set. The breath from the myocardial infarction patients were separated from that of the healthy individuals and the stable coronary artery disease patients with a classification accuracy rate of 97.19 %. The breath from the stable coronary artery disease patients were separated from the breath of the healthy control subjects with a classification accuracy rate of 81.48 %. The results reveal that the proposed method has great potential for myocardial infarction, stable coronary artery disease and healthy subjects when the electronic nose is used to record the exhaled respiratory air of the participants.

Introduction

An electronic nose is a device that uses electrochemical sensors to determine the proportions of volatile chemicals dissolved in the air. Electronic noses contain a variety of gas sensors. They are also commonly used commercially. An extensive number of studies have been conducted recently to determine the freshness [1,2], spoilage [3,4], quality [5,6] and type [7,8] of various foods and beverages using an electronic nose. Electronic noses can also determine indoor air quality [9], and detect air pollution and toxic gases [10,11]. They are also used for environmental monitoring and to detect odors in the cosmetic and fragrance industry [12,13].

In recent years, the detection of disease by the electronic nose has attracted considerable attention. The attraction of an electronic nose diagnosis is the time and cost savings, as well as the ability to take samples from the patient in a non-invasive manner. Many studies have been conducted on diagnosing diseases using an electronic nose. More specifically, lung cancer disease was diagnosed with high accuracy [14,15]. The breath of 10 lung cancer patients was successfully separated from the breath of 10 chronic obstructive pulmonary disease (COPD) patients and 10 healthy individuals [16]. Asthma has been diagnosed [17]. The breath of 30 COPD patients was successfully separated from the breath of 20 asthma patients with 96 % success and 20 healthy smokers with 66 % success [18]. Breath samples of 18 children with obstructive sleep apnea syndrome and 10 healthy children were classified with 64 % accuracy [19]. The urine samples of type 2 diabetic mellitus patients and healthy control groups were separated from each other with 94 % success [20]. The breath of 27 decompensated heart failure (DHF) patients, 25 compensated heart failure (CHF) patients and 28 healthy individuals (control group (CON)) were classified with respective accuracies of 76 % DHFCON, 87 % DHFCHF and 85 % CONCHF by considering 10 times the body odors from their skin with the e-nose [21]. In another study, the exhaled breaths of 10 DHF patients, 16 CHF patients, and 13 healthy subjects were classified with accuracies of 91 % for DHFCHF, 97 % for CHFCON and 100 % for DHFCON, respectively [22].

As stated previously, researchers have generally focused on the diagnosis of lung and respiratory diseases with the electronic nose. This is not where the electronic nose studies should end. Gas chromatography results provided by Machado et al. [23] illustrate that the human breath contains more than two hundred volatile organic compounds, most of which appear in the exhaled breath given by the diffusion of some organic compounds from the alveolar capillary to inhaled air in the lung [24]. This has been the starting point of our hypothesis. In our opinion, diseases that are currently detectable by blood tests are likely to be detected by the breath, despite similar or different chemical mechanisms in the blood.

In light of this hypothesis, we conducted our studies on myocardial infarction (MI). MI is the most important cause of mortality and disability worldwide [25]. Diagnosis is based on clinical features, electrocardiography (ECG) and elevated values of biochemical markers. The most common type of myocardial infarction is an atherosclerotic plaque rupture. Early diagnosis is particularly valuable for the MI group, so they can be revascularized early. The ST segment elevation observed on the ECG is essential for percutaneous coronary intervention (PCI) guidance in MI patients (ST elevation myocardial infarction (STMI)). In patients presenting chest pain, but no ST elevation in the ECG, this diagnosis can only be made by observing the elevation of the cardiac biomarkers. Diagnosis of nonST elevation myocardial infarction (NSTMI) can only be determined by measuring the level of troponin in the blood; this blood test takes approximately 45–60 min. Therefore, patients suspected of NSTMI experience a minimum delay of 1 h before starting their treatment.

It is very important to quickly diagnose a heart attack to begin treatment as soon as possible. Troponin is a protein released in the cardiac myocytes with impaired ischemic damage; it is also the main biochemical marker in the diagnosis of these patients. Troponin is not the only substance that is released. A significant portion of these other substances are eliminated by renal and hepatic clearance. However, some may be excreted by exhaled breath. This has yet to be scientifically determined.

The diagnosis of stable coronary artery disease (SCAD) is different from that of myocardial infarction. Non-invasive imaging methods for a SCAD diagnosis include: Exercise electrocardiography (ExECG), myocardial nuclear perfusion imaging, single-photon emission computed tomography and computed tomography. If necessary, the diagnosis can be confirmed and revascularization can be performed by coronary angiography (CAG). In this study, SCAD patients consisted of patients who were pre-diagnosed with non-invasive tests and confirmed by CAG; their serious lesions were revascularized with PCI.

In this study, we aimed to demonstrate that the breath of myocardial infarction patients, SCAD patients and healthy individuals, can successfully be separated with an electronic nose to a high accuracy.

Section snippets

Subjects and study design

Thirty-five patients who were directed to the coronary intensive care unit of the Cardiology Clinic from the Emergency Department of the Hitit University Erol Olçok Education and Research Hospital with a diagnosis of MI who underwent CAG for primary PCI, were included in the study. The STMI and NSTMI diagnoses were established by clinical features, ECG findings and elevated myocardial necrosis markers.

The inclusion and exclusion criteria were as follows. Our patient group was formed by patients

Results

In this study, we classified the MI, SCAD and healthy subjects using an electronic nose which recorded the exhaled respiratory air of the participants. The divide and conquer multi-class classification technique was used to determine the final label of the trials. In the first classification node, the trials of the MI patients and the rest of the trials were classified. As previously mentioned, the most effective features were determined after performing the forward feature selection method a

Discussion and conclusion

In this paper, we proposed a statistical features-based method for classifying MI, SCAD and healthy subjects using an electronic nose, which acquired the exhaled breath of the participants. Our approach was successfully applied to our dataset, which consists of 362 breath trials collected from 81 subjects. The experiments proved that the SVM has more capability than the k-NN and NN classifiers. It achieved average CA rates of 97.19 % and 81.48 % on the test data for MI versus the rest and the

CRediT authorship contribution statement

Bilge Han Tozlu: Conceptualization, Methodology, Software, Investigation, Resources, Writing - original draft, Writing - review & editing, Supervision, Project administration. Cemaleddin Şimşek: Conceptualization, Methodology, Writing - original draft, Writing - review & editing, Visualization. Onder Aydemir: Conceptualization, Methodology, Software, Validation, Formal analysis, Writing - original draft, Writing - review & editing, Visualization. Yusuf Karavelioglu: Conceptualization,

Declaration of Competing Interest

None.

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