Porth's Essentials of Pathophysiology, 4e

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Circulatory Function

U N I T 5

with anterior and posterior leaflets moving together; slow early diastolic filling of the ventricle; and left atrial enlargement. A. What is the probable cause of this woman’s symptoms? B. Explain the pathologic significance of the slow early diastolic filling, distended left atrium, and palpitations. C. Given the echocardiographic data, what type of cardiac murmur would you expect to find in this woman? D. Which circulation (systemic or pulmonary) would you expect to be affected as this woman’s mitral valve disorder progresses? 3. A 4-month-old male infant is brought into the pediatric clinic by his mother. She reports that she noted over the past several weeks that her baby’s lips and mouth and his fingernails and toenails have become a bluish-gray color. She also states that he seems to tire easily and that even nursing seems to wear him out. Lately, he has had several spells where he has suddenly turned blue, has had difficulty breathing, and has been very irritable. During one of these spells he turned limp and seemed to have passed out for a short time. An echocardiogram reveals a thickening of the right ventricular wall with overriding of the aorta, a large subaortic ventricular septal defect, and narrowing of the pulmonary outflow with stenosis of the pulmonary valve. A. What is this infant’s probable diagnosis? B. Describe the shunting of blood that occurs with this disorder and its relationship to the development of cyanosis. C. The mother is instructed to place the infant in the knee–chest position when he has one of the spells in which he becomes blue and irritable. How does this position help to relieve the cyanosis and impaired oxygenation of tissues? D. The surgical creation of a shunt between the aorta and pulmonary artery may be performed as a palliative procedure for infants with marked hypoplasia of the pulmonary artery, with corrective surgery performed later in childhood. Explain how this procedure increases blood flow to the lungs.

SUMMARY CONCEPTS (continued)

R E V I EW E X E R C I S E S 1. A 40-year-old man presents in the emergency department complaining of substernal chest pain that is also felt in his left shoulder. He is short of breath and nauseated. His blood pressure is 148/90 mm Hg and his heart rate is 110 beats/minute. His ECG shows an ST-segment elevation with T-wave inversion. He is given aspirin, morphine, and oxygen. Blood tests reveal elevated CK-MB and troponin I. A. What is the probable cause of the man’s symptoms? B. Explain the origin of the left arm pain, nausea, and increased heart rate. C. What is the significance of the ST-segment changes and elevation in CK-MB and troponin I? D. Relate the actions of aspirin, morphine, and oxygen to the treatment of this man’s condition. 2. A 50-year-old woman presents with complaints of paroxysmal nocturnal dyspnea and orthopnea, palpitations, and fatigue. An echocardiogram demonstrates a thickened, immobile mitral valve ■■ Congenital heart defects are commonly classified according to anatomic site (e.g., atrial or ventricular septal), hemodynamic alterations (shunting of blood), and their effect on pulmonary blood flow and tissue oxygenation (noncyanotic, cyanotic). ■■ Hemodynamic alterations may produce shunting of blood from the right to the left or from the left to the right side of the heart, with the direction and degree of shunt depending on the size and position of the defect that connects the two sides of the heart and the difference in resistance between the two sides of the circulation. Left-to- right shunts typically increase the volume of the right side of the heart and pulmonary circulation, and right-to-left shunts transfer deoxygenated blood from the right side of the heart to the left side, diluting the oxygen content of blood that is being ejected into the systemic circulation and causing cyanosis. ■■ Kawasaki disease is an acute vasculitis of young children that affects the skin, brain, eyes, joints, liver, lymph nodes, and heart.The disease can produce aneurysmal disease of the coronary arteries and is the most common cause of acquired heart disease in young children.

R E F E R E N C E S

1. Gaziano TA, Gaziano JM. Global burden of cardiovascular disease. In: Bonow R, Mann DL, Zipes DP, et al., eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine . 9th ed. Philadelphia, PA: Saunders Elsevier; 2012:1–22. 2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy . 6th ed. Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams & Wilkins; 2010:144–148.