Split S2 - wikipedia Split S2 Wiggers diagram of various events of a cardiac cycle, with 2nd heart sound at bottom. A split S2 is a finding upon auscultation of the S2 heart sound. It is caused when the closure of the aortic valve ( A ) and the closure of the pulmonary valve ( P ) are not synchronized normally. In a healthy person A is followed by P. Contents 1 Physiological split 1.1 Steps 1.2 Analysis of pressure 2 Pathological split 3 References Physiological split During inspiration, the chest wall expands and causes the intrathoracic pressure to become more negative ( think of a vacuum ). The increased negative pressure allows the lungs to fill with air and expand. While doing so, it also induces an increase in venous blood return from the body into the right atrium via the superior and inferior venae cavae, and into the right ventricle by increasing the pressure gradient ( blood is being pulled by the vacuum from the body and towards the right side of the heart ). Simultaneously, there is a reduction in blood volume returning from the lungs into the left atrium ( the blood wants to stay in the lungs because of the vacuum surrounding the lungs, and PVR is lower because of lung expansion ). Since there is an increase in blood volume in the right ventricle during inspiration, the pulmonary valve ( P component of S ) stays open longer during ventricular systole due to an increase in ventricular emptying time, whereas the aortic valve ( A component of S ) closes slightly earlier due to a reduction in left ventricular volume and ventricular emptying time. Thus the P component of S is delayed relative to that of the A component. This delay in P versus A is heard as a slight broadening or even `` splitting '' of the second heart sound ; though it is usually only heard in the pulmonic area of the chest because the P is soft and not heard in other areas. During expiration, the chest wall collapses and decreases the negative intrathoracic pressure ( compared to inspiration ). Therefore, there is no longer an increase in blood return to the right ventricle versus the left ventricle and the right ventricle volume is no longer increased. This allows the pulmonary valve to close earlier such that it overlaps the closing of the aortic valve, and the split is no longer heard. It is physiologically normal to hear a `` splitting '' of the second heart tone in younger people, during inspiration and in the `` pulmonary area '', i.e. the 2nd ICS ( intercostal space ) at the left edge of the sternum. Steps Chest wall expands during inspiration Intrathoracic pressure becomes more negative to form a vacuum Venous return from the body to the right heart increases, venous return from the lungs to the left heart decreases Analysis of pressure According to Harrison 's Principles of Internal Medicine, `` Normally, blood pressure falls during inspiration ( equal or less than 10 mmHg ), due to an increase in blood flow into the right ventricle with displacement of the interventricular septum to the left, decreasing left ventricular filling and cardiac output ''. The pressure in the right ventricle tries to open the pulmonary valve. The pressure in the pulmonary artery tries to close the pulmonary valve. Remember that the higher pressure will `` win ''. Hence, the closure of the pulmonary valve ( P ) will be delayed since the pressure in the right ventricle is increased in inspiration, opposing the pressure in the pulmonary artery and keeping it open longer than in expiration. The change in A is not that evident. Thus P appears after A in inspiration. Pathological split The different types of split S can be associated with medical conditions : Split during inspiration : normal. ( See above ) Wide splitting : seen in conditions that delay RV emptying ( pulmonic stenosis, RBBB ). Delay in RV emptying causes delayed pulmonic sound ( regardless of breath ) ; it is an exaggeration of normal splitting sounds. Split during expiration : Reverse splitting indicates pathology. Aortic stenosis, hypertrophic cardiomyopathy, left bundle branch block ( LBBB ), and a ventricular pacemaker could all cause a reverse splitting of the second heart sound. Split during both inspiration and expiration : If splitting does not vary with inspiration, it is termed a `` fixed split S '' and is usually due to a septal defect, such as an atrial septal defect ( ASD ). The ASD creates a left to right shunt that increases the blood flow to the right side of the heart, thereby causing the pulmonary valve to close later than the aortic valve independent of inspiration / expiration. A bundle branch block either LBBB or RBBB, ( although RBBB is known to be associated only with S1 split ), will produce continuous splitting but the degree of splitting will still vary with respiration. When the pulmonary valve closes before the aortic valve, this is known as a `` paradoxically split S ''. On physical exam, paradoxical splitting is appreciated as increased splitting on expiration relative to inspiration, versus normal splitting where inspiration will increase splitting. It is seen in conditions that delay left ventricular emptying ( e.g., aortic stenosis, left bundle branch block ). References Jump up ^ `` The Auscultation Assistant - Split S2 ''. Retrieved 2009 - 01 - 09. Jump up ^ `` casemed.case.edu ''. Retrieved 2009 - 01 - 09. Jump up ^ Loscalzo, Joseph ; Charles M. Wiener ; Bloomfield, Gerald T. ; Fauci, Anthony S. ; Braunwald, Eugene ; Dennis L. Kasper ; Hauser, Stephen L ; Longo, Dan L. ( 2008 ). Harrison 's principles of internal medicine : self - assessment and board review. McGraw - Hill Medical. ISBN 0 - 07 - 149619 - X. Question 29 disorders of the cardiovascular system Jump up ^ Mayra Perez ; Lindsay K. Botsford ; Winston Liaw ( 18 October 2007 ). Deja Review : Family Medicine. McGraw Hill Professional. pp. 28 --. ISBN 978 - 0 - 07 - 148568 - 5. Retrieved 11 November 2010. Jump up ^ Dan Longo. Principles of Internal Medicine. McGraw Hill Medical. pp. 1826 -- 1827. ISBN 978 - 0 - 07 - 174890 - 2. Jump up ^ Salvatore Mangione ( 2000 ). Physical diagnosis secrets. Elsevier Health Sciences. pp. 215 --. ISBN 978 - 1 - 56053 - 164 - 7. Retrieved 11 November 2010. Jump up ^ Ellen Chiocca ( 1 March 2010 ). Advanced Pediatric Assessment. Lippincott Williams & Wilkins. pp. 379 --. ISBN 978 - 0 - 7817 - 9165 - 6. Retrieved 11 November 2010. Symptoms and signs relating to the cardiovascular system ( R00 -- R03, 785 ) Chest pain Referred pain Angina Aerophagia Auscultation Heart sounds Split S2 S3 S4 Gallop rhythm Heart murmur Systolic Diastolic Continuous Pericardial friction rub Heart click Bruit carotid Pulse Tachycardia Bradycardia Pulsus tardus et parvus Pulsus paradoxus doubled Pulsus bisferiens Dicrotic pulse Pulsus bigeminus Pulsus alternans Pulse deficit Vascular disease Gangrene Other Palpitations Apex beat Cœur en sabot Jugular venous pressure Cannon A waves Hyperaemia Shock Cardiogenic Hypovolemic Distributive Septic Neurogenic Retrieved from `` https://en.wikipedia.org/w/index.php?title=Split_S2&oldid=763518637 '' Categories : Cardiology Hidden categories : Use dmy dates from November 2010 Talk Contents About Wikipedia Español Edit links This page was last edited on 3 February 2017, at 18 : 45. 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Question: causes of reverse splitting of second heart sound
Answer: Aortic stenosis