Ebook Bedside cardiology: Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Bedside cardiology: Part 2
Ebook Bedside cardiology: Part 2
Second HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2f the retrograde flow of the blood column in the aorta or pulmonary artery by the closed lensed valves set the vibration of the cardiohemic system. The high frequency components of this vibration produce the S2.SplittingPhysiological Splitting (Fig. 15-1)Left ventricular ejection begins and complete Ebook Bedside cardiology: Part 2s earlier than right ventricle. Thus, aortic component (A2) occurs 10 to 15 ms earlier than the pulmonary component (P2). One cannot appreciate two coEbook Bedside cardiology: Part 2
mponents unless the split is more than 30 50 ms. This causes the S2 single during expiration. where the split is less than 15-20 ms.In inspiration, thSecond HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2ed because of the effect of inspiration on the aortic and pulmonary hang out time.Hang-out time is defined as the interval between the end of the ventricular ejection and closure of the semilunar valve. This lime is longer in pulmonary artery' than the aorta. Pulmonary hang out lime may be up to 60 Ebook Bedside cardiology: Part 2to 70 ms, whereas aortic hang-out time may be below 20 to 30 ms. Semilunar valve is closed only when the pulmonary artery or aortic diastolic pressureEbook Bedside cardiology: Part 2
crosses that of the respective ventricle. Pulmonary vasculature is more compliant than the systemic vasculature, pulmonary vascular resistance is oneSecond HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2ssure building up in the pulmonary artery than in the aorta for this cross nv»r rt-'iiT I116Bedside CardiologyA2 p?Expiation fywiy polluteInspiration >" ng postureExpirationSđtng postureFig. 15-1: Physiological splitting of S2. (A) During inspiration, P2 is delayed and A2 occurs earlier. Inspiratory Ebook Bedside cardiology: Part 2 shifting of P2 is more than shifting of A2; (B) In lying down posture, due to increased preload, $2 may appear as persistently splitted, due to audibEbook Bedside cardiology: Part 2
ly wide expiratory splitting; (C) In sitting posture, expiratory splitting narrows down and becomes audibly single. Thus proper assessment of 52 splitSecond HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2he pressure curve is called incisura, which coincides with S2. Hang-out time can also be defined as the distance between the ventricular pressure curve and the aortic or pulmonary incisura. Actual cusp apposition occurs before the incisura. Due to inertia, the forward flow continues. Duration of thi Ebook Bedside cardiology: Part 2s forward flow determines the hang-out time and depends on the vascular capacitance, vascular resistance and the recoil property of the aorta vs pulmoEbook Bedside cardiology: Part 2
nary artery.During inspiration, there is increased pulmonary vascular capacitance resulting in longer pulmonary artery hang-out time and increased venSecond HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2ation I'OIICIJCtnfforhz'irai'ti' nracemv U’ht/'h tc troncmirtửrl in nnlmAtnn'Second Heart Sound (S2) 117Hangout intervalFig. 15-2: Hang-out interval, which is defined as the interval between the end of the ventricular ejection and closure of the semilunar valve. It is up to 70 ms for P2 and 30 ms fo Ebook Bedside cardiology: Part 2r A2ventricular stroke volume is decreased with shortening of ejection time, resulting in early A2.Pathological Splitting (Table 15-1)Pathological splEbook Bedside cardiology: Part 2
ining of S2 may be related to either the wideness of (he split or the effect of respiration on it.TABLE 15-1Pathological splitting of S2A.Persistent sSecond HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration of Ebook Bedside cardiology: Part 2 of respirations.Pi-*rcictAiit nnnfivi'd cnlittinn mpanc imrmol incniratrmr «.’irt/»ninn nil thi»Second HeartSound (S2)MechanismDuring the closure of the semilunar valves, clapping of the leaflets docs not produce (he sound. Sudden deceleration ofGọi ngay
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