(V.) Signal detection by PowerLab system - instruction (VII.) Examination of pulse by palpation Physiology I - practicals Dep. of Physiology, Fac. of Med., MU, 2015 © Michal Hendrych, Tibor Stračina Pulse (pulsus) • Mechanical manifestation of heart activity • Mechanical wave (pulse wave) arises after each contraction of LV and propagates along the arterial wall Ejection phase of systole (open aortal valve) Diastole (closed aortal valve) Aortal valve contracts behind the pressure wave Aortal wall stretches in forward direction Pressure (pulse) wave STK DTK Palpation of pulse • Where: • A. radialis • A. carotis • A. femoralis • A. brachialis • A. poplitea How: • A. tibialis posterior • A. dorsalis pedis Palpation of pulse • Where: • A. radialis • A. carotis • A. femoralis • A. brachialis • A. poplitea • A. tibialis posterior • A. dorsalis pedis http://docplayer.cz/docs-images/40/13777908/images/page_5.jpg a. carotis a. radialisa. femotalis a. poplitea a. tibialis posterior a. dorsalis pedis aorta abdominalis a. brachialis a. axillaris a. subclavis How: Examination of pulse • Frequency: number of pulses per one minute = pulse rate • Qualities: regularity, compressibility • According qualities, we can describe: • Pulsus regularis • Pulsus irregularis • Pulsus celer (Corrigan´s pulse: P. celer, altus, frequens) • Pulsus tardus • Pulsus durus – hardly compressible pulse – hypertension • Pulsus mollis – easily compressible pulse – hypotension • Pulsus magnus – high amplitude of pulse • Pulsus parvus – small amplitude of pulse • Pulsus filiformis – threadlike pulse – circulatory failure Heart rate • Physiological values: 60 – 100 beats per minute (BPM) at rest • Tachycardia: increased heart rate (> 100 at rest) • Bradycardia: decreased heart rate (< 60 at rest) • Arrhythmia: an abnormality in the heart's rhythm, or heartbeat pattern. The heartbeat can be too slow, too fast, have extra beats, skip a beat, or otherwise beat irregularly Heart rate vs. pulse frequency • Heart rate (HR) is a number of cardiac cycles per minute • computed from ECG • Pulse frequency is a number of pulse cycles per minute • Computed from sphygmography, blood pressure or by palpation of artery • Usually: heart rate = pulse frequency Modulation of HR by autonomic nervous system (ANS) • ANS modulates heart automaticity by modulation of SA node activity • Parasympathetic system – vagus nerve – „nervi retardantes“ • Via M2 receptors • Negative chronotropic effect • Decreased tonus of vagus nerve = increased HR • Sympathetic system – sympathetic cardiac nerves – „nervi accelerantes“ • via β1 receptors • Positive chronotropic effect • Increased sympathetic activity = increased HR • Sympathetic and parasympathetic systems are active simultaneously, but in different intensity… Baroreflex • Short-time control of arterial pressure • Mean arterial pressure (MAP) is detected by baroreceptors in aortic arch and carotic sinus • stretch-receptors (mechanoreceptors) • Afferent fibres: vagus nerve (n. X.) and n. glosopharingeus • Centre: rostral part of nucleus solitarius in medulla oblongata • Efferent pathways: • Cardiac branch: n. vagus (+ SS) – heart rate changes • Peripheral (vascular) branch: sympathetic vascular innervation – changes of total peripheral resistance (TPR) • Mechanism: ↓MAP ↓afferentation from baroreceptors processing • ↓vagus activity and ↑sympathetic activity • ↑HR and ↑TPR (MAP = HR * SV * TPR) • ↑MAP … and conversely in case of MAP increase Baroreflex Respiratory sinus arrhythmia (RSA) • Changes of heart rate in accordance with breathing: increase of HR during inspirium, decrease of HR during expirium • The most evident in young people, associated with vagal activity • RSA disappears with HR increase (stress, exercise, high age) ECG BP respiration time [s] Mechanisms of RSA formation: • Baroreflex: during inspiration – ↓ intrathoracic pressure → ↑venous return (due to ↑ pressure gradient) → ↑systolic volume → ↑MAP → baroreflex (2 s lag) → ↓HR → ↑ (balance of) MAP • Central origin: irradiation of respiratory centre to kardiomotoric centre in the medulla oblongata • Bainbridge reflex: ↑venous return during inspirium – stretch of atria – activation of stretch-receptors – stimulation of n. vagus – stimulation of SA node • Local source: mechanical stretch of SA node accelerates its depolarization (weak RSA is presented in transplanted heart) • Another reflexes influencing vagal activity, chemoreflex (oscillation of pCO2, pO2, pH) Zdroje obrázků • Slide 6 - https://www.pinterest.com/pin/144537469264742090/ [cited 31.8.2015] • Slide 6 - http://www.angiologist.com/general-medicine/pulse-palpation-andpulse-location/ [cited 31.8.2015] • Slide 12 - http://corposcindosis.wikia.com/wiki/File:Baroreflex.jpg [cited 31.8.2015] • Slide 14 - http://www.cardiachealth.org/postural-orthostatic-tachycardiasyndrome-pots [cited 31.8.2015]