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Transcript
Physiologic anatomical peculiarities of the heart and blood vessels in children. Percussion of theDoc. heart. Nykytyuk S.O. Timeline for development of the heart Paired endocardial tubes form in cardiogenic region of splanchnic mesoderm Fuse to form a single heart tube Ectoderm - blue Mesoderm - red Endoderm - yellow Four layers contribute to the wall of the heart tube Lumen of heart Constrictions & expansions foreshadow adult heart Development of the septae of the heart • The single heart tube is divided into four definitive chambers by internal partitioning during weeks 4-7 1. Interatrial 2. Atrioventricular 3. Interventricular 4. Ventricular outflow tract • Many congenital heart defects arise during septation Fetus Neonate Fetal and neonatal circulatory systems: shunts and changes at birth 1. Fetal foramen ovale shunts blood from right to left atrium •Adult remnant is fossa ovalis 2. Fetal ductus arteriosus shunts 90% of blood from pulmonary trunk to aorta •Adult remnant is ligamentum arteriosum 3. Fetal ductus venosus shunts 50% of blood from umbilical vein to inferior vena cava by passing liver •Adult remnant is ligamentum venosum Differences in circulatory systems Prenatal: • • • • Little pulmonary blood flow Gas exchange via placenta Nutrient delivery to fetus through placenta Right to left shunting of blood in heart Postnatal: • Functional pulmonary respiration and gas exchange • Loss of placental circulation • Occlusion of right to left shunt in heart and fetal anastomoses Congenital heart defects • Most common type of congenital malformations • Incidence of nearly 1% of live births • Causes elusive, multifactoral: single gene & chromosome defects, environmental factors, viruses, toxins, alcohol, drugs • Specific etiology unknown in many cases but most arise during critical period of heart dev. 20-50 days after fertilization • Well tolerated before birth because of fetal shunts • Most produce symptoms postnatally DIAGNOSTIC EVALUATION 1. 2. 3. 4. Anamnestic Physical examination: inspection palpation percussion auscultation( although the latter is the most significant) FIGURE 26–1 Fetal circulation. Blood leaves the placenta and enters the fetus through the umbilical vein. The ductus venosus, the foramen ovale, and the ductus arteriosus allow the blood to bypass the fetal liver and lungs. After circulating through the fetus, the blood returns to the placenta through the umbilical arteries. From Ladewig, P. W., London, M. L., Moberly, S., & Olds, S. B. (2002). Contemporary Maternal-Child Nursing Care (8th ed,. p. 51 ). Upper Saddle River, NJ: Prentice Hall. Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 26–2 A, Fetal (prenatal) circulation. B, Pulmonary (postnatal) circulation. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Normal pressure gradients and oxygen saturation levels in the heart chambers and great vessels. The ventricle on the right side of the heart has a lower pressure during systole than the left ventricle because less pressure is needed to pump blood to the lungs than to the rest of the body. FIGURE 26–3 Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. THE PECULIARITIES OF INTRAUTERINE CIRCULATION. Superior vena cava Pulmonai artery Plumonary vein Descending aorta Inferior vena cava Postnatal circulation. Spumoni artery Pulmonary vein Ligamentum teres Transitional circulation in the newborn. 1. 2. 3. 4. 5. • The mechanism of transition of the cardiovascular system to the extrauterine functioning is as follows. The infant's first breath raises p02, which causes dilatation of the pulmonary arterial blood vessels and allow blood to flow freely to the lungs. Now the pulmonary blood pressure is decreased. The umbilical arteries constrict in response to higher p02 levels, and the cord is cut. The umbilical arteries turn into the lateral umbilical ligaments. Circulation through the umbilical vein ends. Later, the umbilical vein becomes the round ligament. As the venous duct closes, the systemic blood pressure rises. Later the venous duct turns into the venous ligament. These changes in pressures cause blood flow through the arterial duct to reverse its direction, thus changing one of the "righttoleft" shunts. The arterial duct then constricts (also in response to higher pC«2 levels), preventing blood flow through it by the end of the first day. It will later become the arterial ligament. 1. Since there is now an increased blood flow to the lungs, there must be an increased flow from the lungs through the pulmonary veins and to the left atrium. 2. The increased pressure of this blood against the oval foramen forces it to close against the interatrial septum. This reverses the other "right-to-left" shunt (the site of the old oval foramen will later become the oval fossa). 3. The above changes make it possible for blood to flow to the newborn lungs for gas exchange and return to the heart for distribution to the body. All foetal vessels (umbilical arteries and veins, venous and arterial ducts) first functionally and then anatomically adapt to adult circulation by obliteration. The results of the normal transition are as follows. 1.Decrease in pulmonary blood pressure with 2.Resultant increase in pulmonary blood flow. 3.Closure of the oval foramen. 4.Constriction of the arterial duct. 5.End of flow through the umbilical vein. • Failures of this transition are such life-threatening disorders • as persistent foetal circulation or persistent pulmonary hypertension. The heart and blood vessels • Blood vessels. • The arteries of the child are relatively wider than in adults. • The capillaries are particularly wide in infancy. • Contrarily, the veins of young children are relatively narrow. • (In adults the diameter of the veins are twice as wide as the diameter of the arteries). The heart. • The mass of the heart is relatively greater in children than in adults. • In the newborn the weight of the heart is 0.9 % of the body weight, • while in adults it is only 0.5 %. • The initial weight of the heart (17-24 g) • doubles to 6-7 months, • triples between one and two years • , increases fourfold in the fifth year of life, • six fold in the tenth year, • and eleven fold by 16 years of age an increase in the heart weight • lags behind an increase in the body weight. The energy of cardiac growth is higher in the first year of life, between 7 and 14 years it slows down, and again increases at puberty, it means, cardiac growth keeps to the general laws of the bodily growth. • The mass of heart is bigger in boys than in girls. • The right and left ventricles have approximately the equal size in newborn, thickness of their wall is about 5 mm. The atria and main vessels have a relatively larger size in comparison with the ventricles than those in adults. • The growth of the left part of the heart, especially the left ventricle, is more intensive after birth, than the right part. It is caused by an increase of vascular resistance and arterial pressure. • The growth of the heart is accompanied with tissue differentiation. The histological features of the cardiac muscle of children are as follows. 1. Slenderness of muscular fibres, their closer congregation. 2. Poor development of connective tissue. • 3. Muscular cells in newborns and infants are shorter and much thinner than those of adults. 4. Muscle cell nuclei have an elongated oval configuration. 5. The total amount of nuclei is greater than in adults. • The elastic tissue is poorly developed, abundant Automatism Phases of active potential • • • • • 0 – depolarization 1 – beginning rapid repolarization 2 – slowly repolarization or plateau 3 – ending rapid repolarization 4 – rest period. Conductive system of heart 2 – SA node; 3 – Bachman tract; 4 – tracts of Bachman, Venkebach, Torel 6 – AV node 7 – Hiss bungle 8 – right leg of Hiss bungle 9 – anterior brunch of left leg of Hiss bungle 10 – posterior brunch of left leg of Hiss bungle 11 - Kent bungle 12 – Jams bungle Cardiac cycle Systole • 1. period of tension • asynchrony contraction • isometric contraction • (all valves are closed) • 2. period of ejection • protosphigmic interval (opening of semilunear valves) • fast ejection • slow ejection Cardiac cycle Diastole • 1. Period of relaxation • protodiastolic interval (closing of semilunear valves) • phase of isometric relaxation (opening of AV-valves is end of this phase) • 2. Period of filling • phase of rapid filling • phase of slow filling • phase of filling by help of atrium systole Hypoxemia in the infant • below 95% pulse oximetry. • cyanosis results from hypoxemia • perioral cyanosis indicates central hypoxemia • acrocyanosis does not. Response to Hypoxemia • acute: HR increases • chronic: bone marrow produces more RBC to increase the amount of Hgb available for oxygen transport. • Hct>50 is called polycythemia. • increased blood viscosity increases risk of thromboembolism. Cardiac Functioning • 02 requirements are high the first few weeks of life • normally, HR increases to provide adequate oxygen transport • infant has little cardiac output reserve capacity • cardiac output depends almost completely on HR until the heart is fully developed (age 5 yr). Compliance in the infant • in infancy, muscle fibers are less developed and organized • results in less functional capacity or less compliance • less compliance means the infant is unable or less able to distend or expand the ventricles to achieve an increase stroke volume in order to compensate for increased demands. Severe Hypoxemia • children respond with bradycardia • cardiac arrest generally results from prolonged hypoxemia related to respiratory failure or shock • in adults, hypoxemia usually results from direct insult to the heart. • therefore, in children, bradycardia is a significant warning sign of cardiac arrest. GATHERING COMPLAINT • The child of older age can present his/her complaints by himself/herself: • Pain on the area of heart . In this case it is necessary to specify: • character of pain – sharp, blunt, burning, stabbing. • Time when it appears – at night, in the afternoon, constant, after • neuro-psychological stress or physical exercises or in a state of • Rest. • connection of pain with position of the patient – change in pain • • • • • • • • • • • While getting up, in position on the left or right side. . Irradiation of the pain – especially to the left hand. . probable change after taking medicines , ect. Cardiac dyspnea which leads to take deep breath, stop during climbing ,sometimes with groaning. Perceptible heartbeat ( in a state of rest or during physical Excertion. Complaints of general character: rise in temperature, fatigue, weakness, Headache, loss of memory, loss of appetite , loss of body weight,ect. When younger cnugren and especially cnugren of the breast feeding Are ill, gathered complaints are less informative as parents usually notice • Attentive relatives can specify certain Is orders such as: • Sudden shout ,anxiety of child , which atternates with long periods of • Flaccidity , flabbiness and pallor. • Improper sucking: • . A child starts sucking breast , but after short time baby stops. • . Signs of weariness and dyspnea. • . after resting for a while child again starts sucking, but for a • Short time. • The anamnesis of disease • while gathering anamnesis of disease it is necessary to ask the parents in dletails about the dynamics of disease from the moment it started: when and which symptoms appeared first , how they changed (for example if the parents • know about presence of noise , it is necessary to ascertain its features- time of appearance, what noise , its changes, ect.), what are the additional symptoms. • • • • • The anamnesis of life • Gathering anamnesis of life has special significance for cardiovascular • Diseases, in childhood the cardiac pathology can be of congenital genesis or • May develop as complications after various diseases which results to destruction of the myocardium. • Obstetric anamnesis should be carried out very attentively: toxicosis • Of pregnancy, nephropathy, toxoplasmosis, infectious diseases of mother , • Professional exposure to harmful conditions – all this can cause CHD. • • . • • • • • • • As complication of severe and chronic infections, allergic diseases. The most common cause of heart diseases in school children is rheumatic fever. Assuming the probability of rheumatic fever. It is necessary to clarify the following questions : . presence of chronic infection or frequent acute diseases in the upper Respiratory tract ( chronic tonsillitis, qulnsy). . family anamnesis , possibility of hereditary rheumatic fever . if rheumatic fever is repeated, it is necessary to ask in details about its Time , course and previous treatment Inspection examining the chest point of maximum impulse, or apical pulse, respiratory function general physical growth and development presence of all pulses (especially the femoral pulses), distended neck veins, peripheral cyanosis, edema ASSESSMENT OF HEART DISORDERS IN CHILDREN History Physical assessment general appearance pulse, blood pressure, & respirations Hypoxemia in the infant below 95% pulse oximetry. cyanosis results from hypoxemia perioral cyanosis indicates central hypoxemia acrocyanosis does not. Response to Hypoxemia acute: HR increases chronic: bone marrow produces more RBC to increase the amount of Hgb available for oxygen transport. Hct>50 is called polycythemia. increased blood viscosity increases risk of thromboembolism. Compliance in the infant in infancy, muscle fibers are less developed and organized results in less functional capacity or less compliance less compliance means the infant is unable or less able to distend or expand the ventricles to achieve an increase stroke volume in order to compensate for increased demands. clinical symptoms Generalised moderate peripheral cyanosis in a shocked new born with vasomotor instability and poor lung expansion. clinical symptoms A‘ blue baby' There is severe peripheral and central cyanosis. Post-mortem revealed Fallot's tetralogy. Note the malformed low-set ear. clinical symptoms Severe peripheral and central cyanosis Convulsion was produced by increased hypoxia after prolonged crying. Postmortem revealed atresia of the pulmonary artery and a single ventricle. clinical symptoms “pitting” edema Main clinical symptoms in patient with cardiovascular disorders Cardialgies, tachycardia, dyspnea, abdominal pains, heart enlargement, decrease of tones' sonority, rigidity of cardiac rhythm, rhythm of gallop, apical systolic murmur, considerable cardiomegaly, mitral or aortic configuration of the heart at X-ray of the chest, blood circulation's insufficiency, stability or slow progress of heart disturbances, combined ECG-disorders (the disorders of automatism, conductivity, excitability, processes of de-and repolarization), echocardiographic disorders, decreased of myocardium contractive ability, objectively confirmed by the instrumental investigations. Palpation point of maximum impulse (presence of vibratory thrills and pericardial friction rubs) Assessing the quality and symmetry of all pulses (rate, rhythm, volume, and character (alternative, large, swift, dicrotic, intermittent, labile, small, slow, soft, tense, rhythmic, rapid, pulse deficit, pulse flutter, tension of the pulse, full (weak) pulse ) ) Determine blood pressure. Pulse Tachycardia is a puls rate more than 160 bpm in an infant and more than 100 bpm at 3 years of age.Tachycardia is particulary significant if it persist during sleep, when the possibility of exitement is removed. Abnormal pulse pattent that tend to occur in children with heart disorders are shown in Table 1. Abnormal Pulse patterns Pulse patterns Water hammer Description Very forceful and bounding pulse (Corrigan's pulse)and capillary pulsation may be apparent even in the fingernails suggest cardial insufficiency, as in patient ductus arteriosus Pulsus alternant Dicrotic Adouble radial pulse for every apical beat, symptomatic of aortic stenosis Average pulse rates at rest (beats per minute) Newborn 6 months 1 year 2 years 3 years 140-160 130-135 120-125 110 105 4 years 5 years 6-7 years 10 years 12 years 100 98-100 90-85 78-85 70-75 The normal rate is not more then 10 % of average Blood pressure, mmHg Upper extremity Newborn systolic: 70-76 diastolic: 35 For children younger 12 months systolic: 76 + 2 x n (n is age in months) diastolic: 1/2-1/3 of systolic Lower extremity Newborn systolic: 70-76 diastolic:35 For children younger 9 months systolic: 76 + 2 x n (n is age in months) diastolic: 1/2-1/3 of systolic Blood pressure, mmHg Upper extremity 1 year systolic:90-100 diastolic: 60 For children older 1 year systolic: min. 90 + 2 x n (n is age in years) max. 100 + 2 x n (n is age in years) diastolic: 1/2-1/3 of systolic Lower extremity In children older 9-10 months the blood pressure is 5-20 mm Hg more than upper extremity Shock vs. Hypotension Shock State of insufficient perfusion to meet the metabolic demands of tissues Hypotension Physical sign characterized by a fall in systolic blood pressure (BP below normal values) Hypotension is a late sign of shock in children and it’s presence in children implies profound cardiovascular compromise Hypotension Blood Pressure Lowest acceptable systolic blood pressure Birth – 1 month: 60 mmhg 1 month – 1 year: 70 mmhg 1 year – 10 year: 70 + (2 X age in years) >10 years : 90 mmhg Normal systolic 80 + (2 x age in years) or fiftieth percentile Percussion Percussion is used mainly to determine the size of the heart by outlining its borders. Dullness is normally heard over the left area of the heart and partially over the right. Deviation from the expected finding may indicate cardiac enlargement or displacement and warrants further study. Border's of heart relative dullness Border Right Upper Left until 2 years •right parasternal line •the II rib •2 cm outward from left midclavicular line Transvers •6-9 cm Border Right Upper Border Right Border Right Upper Left older 12 years •the right sternal line •the III intercostals space •0.5 cm medially from left midclavicular line Transversal size •9-14 cm al size 7-12 years •Between the right parasternal line and the right sternal line Upper Left Transversa l size •the III rib •0.5 cm outward from left midclavicular line •9-14 cm Left Transversal size 2-7 years •right parasternal line •the II intercostals space •1 cm outward from left midclavicular line •8-12 cm Border's of heart absolute dullness Border Right Upper Left until 2 years •left sternal line •the II intercostal space •1.0-0.5 cm outward from left midclavicular line Transvers •2-3 cm al size Border Right Upper Left Transversa l size 7-12 years •left sternal line •the III intercostal space •Between the left midclavicular line and left parasternal line •5-5.5 cm Border Right Upper Left 2-7 years •left sternal line •the III rib •left midclavicular line Transversal size •4 cm Border Right Upper Left Transversal size older 12 years •left sternal line •the IV rib •left parasternal line •5-5.5 cm Clinical symptoms Tachycardia Bradycardia Pulsus alternans Pulsus bigeminus Increased rate Decreased rate Strong beat followed by weak beat Coupled rhythm in which beat is felt in pairs FIGURE 26–13 Clubbing of the fingers is one manifestation of a cyanotic defect in an older child. What neurologic signs may be associated with such a defect? Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Blue-or-tet-spells FIGURE 26–12 Place the infant who has a hypercyanotic spell in the knee–chest position. This position increases systemic vascular resistance in the lower extremities. Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. FIGURE 26–10 A child with a cyanotic heart defect squats (assumes a knee–chest position) to relieve cyanotic spells. Jane W. Ball and Ruth C. Bindler Child Health Nursing: Partnering with Children & Families © 2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Tests 1. What is the term of formation of the 4-chamber heart in the foetus? a) At 3 weeks of gestation; b) at 5 weeks of gestation; c)at 7 weeks of gestation; d)at 10 weeks of gestation; e)at 18 weeks of gestation. 2. In which of the following foetal vascular structures is oxygen content the lowest? a)The umbilical vein; b)the inferior vena cava; c)the left atrium; b) the umbilical arteries; e) the arterial duct; 3. The change from the foetal to newborn circulation is primarily accomplished by: a)clamping the umbilical cord; b)closure of the arterial duct; c)expansion of the lungs; e) closure of the umbilical arteries; 4. The heart's position in the chest and its relative dullness borders can be influenced by the following factors, except for: a)shape of the chest; b)level of the diaphragm; c)size of the spleen; d)size of the liver; e)meteorism; 5. Tachycardia can be noticed in all the conditions below, but: a)intoxication; b)hyperthermia; c)diseases of the cardiovascular system; d)hyperthyroidism; Answers: 1 - a; 2 - d; 3 - c; 4 - c; 5 - e; 6 - d, Thank you for attention