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<title>Pan–Tompkins algorithm</title>
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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Pan–Tompkins algorithm</span></span>
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<p>The <b>Pan–Tompkins algorithm</b><sup id="cite_ref-PanTompkins_1-0" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> is commonly used to detect <a href="QRS_complexes" class="mw-redirect" title="QRS complexes">QRS complexes</a> in electrocardiographic signals (<a href="ECG" class="mw-redirect" title="ECG">ECG</a>). The QRS complex represents the ventricular <a href="Depolarization" title="Depolarization">depolarization</a> and the main spike visible in an ECG <a href="Signal" title="Signal">signal</a> (see figure). This feature makes it particularly suitable for measuring <a href="Heart_rate" title="Heart rate">heart rate</a>, the first way to assess the heart health state. In the first derivation of <a href="Einthoven" title="Einthoven">Einthoven</a> of a physiological heart, the QRS complex is composed by a downward deflection (Q wave), a high upward deflection (R wave) and a final downward deflection (S wave).
</p><p>The Pan–Tompkins algorithm applies a series of filters to highlight the frequency content of this rapid heart depolarization and removes the background <a href="Noise_reduction" title="Noise reduction">noise</a>. Then, it squares the signal to amplify the QRS contribution, which makes identifying the QRS complex more straightforward. Finally, it applies adaptive thresholds to detect the peaks of the filtered signal. The algorithm was proposed by Jiapu Pan and Willis J. Tompkins in 1985, in the journal IEEE Transactions on Biomedical Engineering.<sup id="cite_ref-PanTompkins_1-1" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The performance of the method was tested on an annotated arrhythmia database (MIT/BIH<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-PhysioNet_3-0" class="reference"><a href="#cite_note-PhysioNet-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>) and evaluated also in presence of noise. Pan and Tompkins reported that the 99.3 percent of QRS complexes was correctly detected.<sup id="cite_ref-PanTompkins_1-2" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
</p>
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<div class="mw-heading mw-heading2"><h2 id="Pre-processing">Pre-processing</h2></div>
<div class="mw-heading mw-heading3"><h3 id="Noise_cancellation">Noise cancellation</h3></div>
<p>As a first step, a <a href="Band-pass_filter" title="Band-pass filter">band-pass filter</a> is applied to increase the <a href="Signal-to-noise_ratio" title="Signal-to-noise ratio">signal-to-noise ratio</a>. A filter bandwidth of 5-15 <a href="Hertz" title="Hertz">Hz</a> is suggested to maximize the QRS contribute and reduce muscle noise, baseline wander, powerline interference and the <a href="P_wave_(electrocardiography)" title="P wave (electrocardiography)">P wave</a>/<a href="T_wave" title="T wave">T wave</a> frequency content.<sup id="cite_ref-PanTompkins_1-3" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> In the original algorithm proposed in 1985, the band-pass filter was obtained with a <a href="Low-pass_filter" title="Low-pass filter">low-pass filter</a> and a <a href="High-pass_filter" title="High-pass filter">high-pass filter</a> in cascade to reduce the computational cost and allow a real-time detection, while ensuring a 3 <a href="Decibel" title="Decibel">dB</a> passband in the 5–12 Hz frequency range, reasonably close to the design goal.
</p><p>For a signal sampled at a frequency of 200 Hz, Pan and Tompkins suggested the filters with the following <a href="Transfer_function" title="Transfer function">transfer functions</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle H(z)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
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<mi>H</mi>
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<annotation encoding="application/x-tex">{\displaystyle H(z)}</annotation>
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</math></span><img src="./b3c5a542a7eaa29c58fb64cbeb5133ce98ac4f4b.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:4.961ex; height:2.843ex;" alt="{\displaystyle H(z)}" loading="lazy"></span> in an updated version of their article:<sup id="cite_ref-PTerrata_4-0" class="reference"><a href="#cite_note-PTerrata-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>
</p>
<ul><li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle H(z)={(1-z^{-5})^{2} \over (1-z^{-1})^{2}}}">
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<annotation encoding="application/x-tex">{\displaystyle H(z)={(1-z^{-5})^{2} \over (1-z^{-1})^{2}}}</annotation>
</semantics>
</math></span><img src="./9b5d98c4a674546c3fa0931be8999a090b8305e3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:19.185ex; height:6.676ex;" alt="{\displaystyle H(z)={(1-z^{-5})^{2} \over (1-z^{-1})^{2}}}" loading="lazy"></span> for a second-order low-pass filter with a gain of 36 and a processing delay of 5 <a href="Sampling_(signal_processing)" title="Sampling (signal processing)">samples</a>;</li>
<li><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle H(z)={(-1/32+z^{-16}-z^{-17}+z^{-32}/32) \over (1-z^{-1})}}">
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<annotation encoding="application/x-tex">{\displaystyle H(z)={(-1/32+z^{-16}-z^{-17}+z^{-32}/32) \over (1-z^{-1})}}</annotation>
</semantics>
</math></span><img src="./7e5d5b1be2908f3cdec355d14e3055598bf28a39.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:41.907ex; height:6.676ex;" alt="{\displaystyle H(z)={(-1/32+z^{-16}-z^{-17}+z^{-32}/32) \over (1-z^{-1})}}" loading="lazy"></span>for a high-pass filter with a unity gain and a processing delay of 16 samples.</li></ul>
<div class="mw-heading mw-heading3"><h3 id="Derivative_step">Derivative step</h3></div>
<p>As a third step, a derivative filter is applied to provide information about the slope of the QRS. For a signal sampled at 200 Hz, Pan and Tompkins suggested the following <a href="Transfer_function" title="Transfer function">transfer function</a>:<sup id="cite_ref-PTerrata_4-1" class="reference"><a href="#cite_note-PTerrata-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup>
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle H(z)=0.1(-z^{-2}-2z^{-1}+2z^{1}+z^{2})}">
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<annotation encoding="application/x-tex">{\displaystyle H(z)=0.1(-z^{-2}-2z^{-1}+2z^{1}+z^{2})}</annotation>
</semantics>
</math></span><img src="./7a2245f62167bdef4e8fd38019d2f40383985559.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:36.63ex; height:3.176ex;" alt="{\displaystyle H(z)=0.1(-z^{-2}-2z^{-1}+2z^{1}+z^{2})}" loading="lazy"></span>for a 5-point derivative filter with gain of 0.1 and a processing delay of 2 samples.
</p>
<div class="mw-heading mw-heading3"><h3 id="Squaring_and_integration">Squaring and integration</h3></div>
<p>The filtered signal is squared to enhance the dominant peaks (QRSs) and reduce the possibility of erroneously recognizing a T wave as an R peak. Then, a moving average filter is applied to provide information about the duration of the QRS complex. The number of samples to average is chosen in order to average on windows of 150 ms.<sup id="cite_ref-PanTompkins_1-4" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The signal so obtained is called integrated signal.
</p>
<div class="mw-heading mw-heading2"><h2 id="Decision_rules">Decision rules</h2></div>
<div class="mw-heading mw-heading3"><h3 id="Fiducial_mark">Fiducial mark</h3></div>
<p>In order to detect a QRS complex, the local peaks of the integrated signal are found. A peak is defined as the point in which the signal changes direction (from an increasing direction to a decreasing direction). After each peak, no peak can be detected in the next 200 ms (i.e. the lockout time). This is a physiological constraint due to the <a href="Refractory_period_(physiology)" title="Refractory period (physiology)">refractory period</a> during which ventricular depolarization cannot occur even in the presence of a stimulus.<sup id="cite_ref-PanTompkins_1-5" class="reference"><a href="#cite_note-PanTompkins-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading3"><h3 id="Thresholds">Thresholds</h3></div>
<p>Each fiducial mark is considered as a potential QRS. To reduce the possibility of wrongly selecting a noise peak as a QRS, each peak amplitude is compared to a threshold (<i>Threshold<sub>I</sub></i>) that takes into account the available information about already detected QRS and the noise level:
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Threshold_{I}=NoiseLevel_{I}+0.25(SignalLevel_{I}-NoiseLevel_{I})}">
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<annotation encoding="application/x-tex">{\displaystyle Threshold_{I}=NoiseLevel_{I}+0.25(SignalLevel_{I}-NoiseLevel_{I})}</annotation>
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</math></span><img src="./bdd8b30d0f179ed0e46613b37fb8301fd62ea358.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:65.316ex; height:2.843ex;" alt="{\displaystyle Threshold_{I}=NoiseLevel_{I}+0.25(SignalLevel_{I}-NoiseLevel_{I})}" loading="lazy"></span>
</p><p>where <i>NoiseLevel<sub>I</sub></i> is the running estimate of the noise level in the integrated signal and <i>SignalLevel<sub>I</sub></i> is the running estimate of the signal level in the integrated signal.
</p><p>The threshold is automatically updated after detecting a new peak, based on its classification as signal or noise peak:
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle SignalLevel_{I}=0.125PEAK_{I}+0.875SignalLevel_{I}}">
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<annotation encoding="application/x-tex">{\displaystyle SignalLevel_{I}=0.125PEAK_{I}+0.875SignalLevel_{I}}</annotation>
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</math></span><img src="./9e6a252460e9b3887eee1b4bc1d06b011c0f64fc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:51.564ex; height:2.509ex;" alt="{\displaystyle SignalLevel_{I}=0.125PEAK_{I}+0.875SignalLevel_{I}}" loading="lazy"></span>(if <i>PEAK<sub>I</sub></i> is a signal peak)
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle NoiseLevel_{I}=0.125PEAK_{I}+0.875NoiseLevel_{I}}">
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<annotation encoding="application/x-tex">{\displaystyle NoiseLevel_{I}=0.125PEAK_{I}+0.875NoiseLevel_{I}}</annotation>
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</math></span><img src="./359bbda3adbd1a6dd4ffc93f68aae8f85843dccf.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:50.429ex; height:2.509ex;" alt="{\displaystyle NoiseLevel_{I}=0.125PEAK_{I}+0.875NoiseLevel_{I}}" loading="lazy"></span>(if <i>PEAK<sub>I</sub></i> is a noise peak)
</p><p>where <i>PEAK<sub>I</sub></i> is the new peak found in the integrated signal.
</p><p>At the beginning of the QRS detection, a 2 seconds learning phase is needed to initialize <i>SignalLevel<sub>I</sub></i> and <i>NoiseLevel<sub>I</sub></i> as a percentage of the maximum and average amplitude of the integrated signal, respectively.
</p><p>If a new <i>PEAK<sub>I</sub></i> is under the <i>Threshold<sub>I</sub></i>, the noise level is updated. If <i>PEAK<sub>I</sub></i> is above the <i>Threshold<sub>I</sub></i>, the algorithm implements a further check before confirming the peak as a true QRS, taking into consideration the information provided by the bandpass filtered signal.
</p><p>In the filtered signal the peak corresponding to the one evaluated on the integrated signal is searched and compared with a threshold, calculated in a similar way to the previous step:
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Threshold_{F}=NoiseLevel_{F}+0.25(SignalLevel_{F}-NoiseLevel_{F})}">
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<annotation encoding="application/x-tex">{\displaystyle Threshold_{F}=NoiseLevel_{F}+0.25(SignalLevel_{F}-NoiseLevel_{F})}</annotation>
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</math></span><img src="./41c902c9ea2d083bb15142a99f635517125ee3ee.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:66.925ex; height:2.843ex;" alt="{\displaystyle Threshold_{F}=NoiseLevel_{F}+0.25(SignalLevel_{F}-NoiseLevel_{F})}" loading="lazy"></span>
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle SignalLevel_{F}=0.125PEAK_{F}+0.875SignalLevel_{F}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>S</mi>
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<annotation encoding="application/x-tex">{\displaystyle SignalLevel_{F}=0.125PEAK_{F}+0.875SignalLevel_{F}}</annotation>
</semantics>
</math></span><img src="./0fef202c7fb0182415fdc16d3e23990d967d51c8.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:52.771ex; height:2.509ex;" alt="{\displaystyle SignalLevel_{F}=0.125PEAK_{F}+0.875SignalLevel_{F}}" loading="lazy"></span>(if <i>PEAK<sub>F</sub></i> is a signal peak)
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle NoiseLevel_{F}=0.125PEAK_{F}+0.875NoiseLevel_{F}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>N</mi>
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<annotation encoding="application/x-tex">{\displaystyle NoiseLevel_{F}=0.125PEAK_{F}+0.875NoiseLevel_{F}}</annotation>
</semantics>
</math></span><img src="./50b596b81c475e210efd867ef4a0a2749007bac9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:51.636ex; height:2.509ex;" alt="{\displaystyle NoiseLevel_{F}=0.125PEAK_{F}+0.875NoiseLevel_{F}}" loading="lazy"></span>(if <i>PEAK<sub>F</sub></i> is a noise peak)
</p><p>where the final F stands for filtered signal.
</p>
<div class="mw-heading mw-heading3"><h3 id="Search_back_for_missed_QRS_complexes">Search back for missed QRS complexes</h3></div>
<p>The algorithm takes into account the possibility of setting too high values of <i>ThresholdI<sub>I</sub></i> and <i>ThresholdI<sub>F.</sub></i> A check is performed to continuously assess the RR intervals (namely the temporal interval between two consecutively QRS peaks) to overcome this issue. The average RR is computed in two ways to consider both regular and irregular heart rhythm. In the first method <i>RRaverage1</i> is computed as the mean of the last RR intervals. In the second method <i>RRaverage2</i> is computed as the mean of the last RR intervals that fell between the limits specified as:
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle RRlow=92\%RRaverage2}">
<semantics>
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<mi>R</mi>
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<mo>=</mo>
<mn>92</mn>
<mi mathvariant="normal">%<!-- % --></mi>
<mi>R</mi>
<mi>R</mi>
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<annotation encoding="application/x-tex">{\displaystyle RRlow=92\%RRaverage2}</annotation>
</semantics>
</math></span><img src="./75870f12d632613beb4dc83e049873b2772ab60f.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:26.982ex; height:2.676ex;" alt="{\displaystyle RRlow=92\%RRaverage2}" loading="lazy"></span>
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle RRhigh=116\%RRaverage2}">
<semantics>
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<mstyle displaystyle="true" scriptlevel="0">
<mi>R</mi>
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<mi>h</mi>
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<mi>h</mi>
<mo>=</mo>
<mn>116</mn>
<mi mathvariant="normal">%<!-- % --></mi>
<mi>R</mi>
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<annotation encoding="application/x-tex">{\displaystyle RRhigh=116\%RRaverage2}</annotation>
</semantics>
</math></span><img src="./6b14712836b40b2af0b67c10ff6c54132ad1f50c.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:29.255ex; height:2.676ex;" alt="{\displaystyle RRhigh=116\%RRaverage2}" loading="lazy"></span>
</p><p>If no QRS is detected in a window of 166% of the average RR (<i>RRaverage1</i> or <i>RRaverage2</i>, if the heart rhythm is regular or irregular, respectively)<i>,</i> the algorithm adds the maximal peak in the window as a potential QRS and classify it considering half the values of the thresholds (both <i>ThresholdI<sub>I</sub> and ThresholdI<sub>F</sub></i>). This check is implemented because the temporal distance between two consecutive beats cannot physiologically change more quickly than this.
</p>
<div class="mw-heading mw-heading3"><h3 id="T_wave_discrimination">T wave discrimination</h3></div>
<p>The algorithm takes particularly into consideration the possibility of a false detection of T waves. If a potential QRS falls up to a 160 ms window after the refractory period from the last correctly detected QRS complex, the algorithm evaluates if it could be a T wave with particular high amplitude. In this case, its slope is compared to that of the precedent QRS complex. If the slope is less than half the previous one, the current QRS is recognized as a T wave and discarded, and it also updates the <i>NoiseLevel</i> (both in the filtered signal and the integrated signal).
</p>
<div class="mw-heading mw-heading2"><h2 id="Application">Application</h2></div>
<p>Once the QRS complex is successfully recognized, the heart rate is computed as a function of the distance in seconds between two consecutive QRS complexes (or R peaks):
</p><p><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\mathit {HR}}\ ({\text{bpm}})={60 \over {\mathit {RR}}\ ({\text{s}})}}">
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<annotation encoding="application/x-tex">{\displaystyle {\mathit {HR}}\ ({\text{bpm}})={60 \over {\mathit {RR}}\ ({\text{s}})}}</annotation>
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</math></span><img src="./8074dea7c09ef6d217b1800459b92a6627f8f0b5.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.671ex; width:20.961ex; height:6.009ex;" alt="{\displaystyle {\mathit {HR}}\ ({\text{bpm}})={60 \over {\mathit {RR}}\ ({\text{s}})}}" loading="lazy"></span>
</p><p>where bpm stands for beats per minute. The HR is often used to compute the <a href="Heart_rate_variability" title="Heart rate variability">heart rate variability</a> (HRV) a measure of the variability of the time interval between heartbeats. HRV is often used in the clinical field<sup id="cite_ref-HRVcirc_6-0" class="reference"><a href="#cite_note-HRVcirc-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> to diagnose and monitor pathological conditions and their treatment, but also in the <a href="Affective_computing" title="Affective computing">affective computing</a> research to study new methods to assess the emotional state of people.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Electrophysiology" title="Electrophysiology">Electrophysiology</a></li>
<li><a href="QRS" class="mw-redirect" title="QRS">QRS</a></li>
<li><a href="Heart_rate" title="Heart rate">Heart rate</a></li>
<li><a href="Heart_rate_variability" title="Heart rate variability">Heart rate variability</a></li>
<li><a href="Affective_computing" title="Affective computing">Affective computing</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
<div class="mw-references-wrap"><ol class="references">
<li id="cite_note-PanTompkins-1"><span class="mw-cite-backlink">^ <a href="#cite_ref-PanTompkins_1-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-PanTompkins_1-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-PanTompkins_1-2"><sup><i><b>c</b></i></sup></a> <a href="#cite_ref-PanTompkins_1-3"><sup><i><b>d</b></i></sup></a> <a href="#cite_ref-PanTompkins_1-4"><sup><i><b>e</b></i></sup></a> <a href="#cite_ref-PanTompkins_1-5"><sup><i><b>f</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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/* end https://en.wikipedia.org/ */
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<li id="cite_note-HRVcirc-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-HRVcirc_6-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFTask_Force_of_the_European_Society_Electrophysiology1996" class="citation journal cs1">Task Force of the European Society Electrophysiology (March 1996). "Heart Rate Variability". <i>Circulation</i>. <b>93</b> (5): <span class="nowrap">1043–</span>1065. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1161%2F01.CIR.93.5.1043">10.1161/01.CIR.93.5.1043</a>.</cite></span>
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<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite id="CITEREFNardelliValenzaGrecoLanata2015" class="citation journal cs1">Nardelli, Mimma; Valenza, Gaetano; Greco, Alberto; Lanata, Antonio; Scilingo, Enzo Pasquale (2015-10-01). "Recognizing Emotions Induced by Affective Sounds through Heart Rate Variability". <i>IEEE Transactions on Affective Computing</i>. <b>6</b> (4): <span class="nowrap">385–</span>394. <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FTAFFC.2015.2432810">10.1109/TAFFC.2015.2432810</a>. <a href="Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://hdl.handle.net/11568%2F765947">11568/765947</a></span>. <a href="ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/1949-3045">1949-3045</a>.</cite></span>
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