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Trigeminal cardiac reflex in post-operative spheno-orbital meningioma
Published in Cut Adeya Adella, Stem Cell Oncology, 2018
A 48-year-old female presented with left proptosis bulbi as the chief complaint. This happened since six years. She could no longer see through her left eye, but its movement was still good. There was no history of headache, vomiting spit, convulsion, or one-sided paresis. She was diagnosed as having left spheno-orbital meningioma, and required a craniotomy tumour removal. A cranio-orbitozygomatic approach was used. She was transferred to intensive care for post-operative care with a stable haemodynamic profile. Six hours postoperatively, her HR suddenly decreased (baseline 80-88) to 55-60 beats per minute (31% decrease). The ECG showed sinus rhythm. The MABP also decreased to 52 mmHg (baseline 80 mmHg; 35% decrease). Post-operative haemoglobin was 11 g/dL, central venous pressure was 12 mmHg, and other laboratory findings were normal. Her oxygen saturation was 100%, and no hypercarbia occurred. She was suspected of suffering TCR. Intravenous administration of atropine (2 mg) abolished the reflex, and HR and MABP slowly increased to normal.
Electrocardiogram
Published in Kayvan Najarian, Robert Splinter, Biomedical Signal and Image Processing, 2016
Kayvan Najarian, Robert Splinter
An important disease that is often detected in the frequency domain is sinus tachycardia. A sinus rhythm of higher than 100 beats per minute is called sinus tachycardia. Similar conditions often occur as a physiological response to physical exercise or physical stress, but, in diseased cases, the condition results from congestive heart failure. More specifically, if the sinus rhythm is irregular such that the longest PP or RR intervals exceed the shortest interval by 0.16 s, the situation is diagnosed as sinus arrhythmia. This condition is very common in all age groups but more common in teenagers and preteens who may have never considered having a heart disease. One potential origin for the sinus arrhythmia may be the vagus nerve, which regulates respiration as well as heart rhythm. The nerve is active during respiration and through its effect on the sinus node, causes an increase in heart rate during inspiration and a decrease during expiration.
Mathematical Techniques Applied to Clinical Surveillance
Published in John R. Zaleski, Clinical Surveillance, 2020
Both Figures 4.12 and Figure 4.13 show the dominant signal frequency to be approximately 1.4 Hz–1.4 cycles per second. There is a secondary frequency of lesser dominance at approximately 2.8 Hz. The dominant frequency of 1.4 Hz translates into a heart rate frequency of approximately 84 beats per minute (bpm)—in the range of normal sinus rhythm. The principal frequencies determined in both Figure 4.12 and Figure 4.13 show that, despite the artifact, the frequency is centered about the primary or principal value of 84 bpm. The power spectral density identifies the dominant frequencies in a signal by the peaks of the PSD function at a specific value of frequency. In this way, the underlying frequencies of the time-series data can be determined.
Feature extraction of ECG signal
Published in Journal of Medical Engineering & Technology, 2018
Shanti Chandra, Ambalika Sharma, Girish Kumar Singh
Electrocardiogram (ECG) is the recording of electrical activity of the heart. Analysis of ECG signal is very important to diagnose a cardiac patient. During the analysis of an ECG signal, various features are extracted, viz., the P wave, QRS complex, T wave, etc., that are depicted in Figure 1. In this figure, P wave, QRS complex and T wave indicate the depolarisation of atria, depolarisation of ventricles and repolarisation of ventricles, respectively. Any change in these components (i.e. amplitude, duration and shape) can indicate an arrhythmia. Duration between onset points of two consecutive P waves is defined as one heartbeat. However, duration of two consecutive R-peak points is considered as one beat duration (one cardiac cycle) because R-peak detection is much simpler than detection of P-peaks/waves. Heart rate is the number of heart beats in one minute. Detection of R-wave is very important to measure the heart rate and detection of other features. The heart rate between 60 and 100 beats/min is considered as a normal heart rate or normal sinus rhythm (NSR). However, the heart rate less than 60 beats per minute is called bradycardia, and greater than 100 beats per minute is known as tachycardia [1].
Calibration of Electrocardiograph (ECG) Simulators
Published in NCSLI Measure, 2018
Steven Yang, Brenda Lam, Chris M. N. Ng
Conventional 12-lead ECG uses ten electrodes on the patient’s limbs and across the chest to measure the electrical potential of the heart. During each heartbeat, a healthy heart has an orderly progression of depolarization and repolarization. The major components of a heart beat can be graphically identified from the ECG output, which is generally called the normal sinus rhythm. An example of a single normal sinus heart beat is shown in Figure 1. Distinctive peaks and durations contain important information for medical diagnosis. They are identified as P wave, QRS complex, and T wave, which represent atrial depolarization, ventricular depolarization and ventricular repolarization, respectively. For a heartbeat of 60 beats per minute (BPM), the time duration from P to T is around 560–640 ms, and the time duration from Q to S is around 80–100 ms.