{"id":5675,"date":"2025-12-13T17:37:51","date_gmt":"2025-12-13T22:37:51","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/?post_type=chapter&#038;p=5675"},"modified":"2025-12-13T17:53:48","modified_gmt":"2025-12-13T22:53:48","slug":"congenital-heart-defects","status":"web-only","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/chapter\/congenital-heart-defects\/","title":{"raw":"7p30  Congenital Heart Defects","rendered":"7p30  Congenital Heart Defects"},"content":{"raw":"<h1><strong>Congenital Heart Defect Definition:\u00a0<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Abnormal heart formation<\/strong> during <strong>embryonic development<\/strong> in the <strong>uterus<\/strong><\/li>\r\n \t<li><strong>Multiple causes<\/strong> (discussed later)<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Physiological consequences:<\/strong><\/h1>\r\n<ul>\r\n \t<li><strong>Defective heart \u2192 decreased function<\/strong>\r\n<ul>\r\n \t<li><strong>\u2193 Stroke volume<\/strong><\/li>\r\n \t<li><strong>\u2193 Cardiac output<\/strong><\/li>\r\n \t<li>Meets definition of <strong>congestive heart failure (CHF)<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Physiological consequences<\/strong>\r\n<ul>\r\n \t<li><strong>\u2193 Oxygenated blood delivery<\/strong> to tissues<\/li>\r\n \t<li><strong>Delayed growth and development<\/strong><\/li>\r\n \t<li><strong>Poor weight gain<\/strong><\/li>\r\n \t<li><strong>\u2193 ATP production<\/strong> \u2192 impaired <strong>mitosis<\/strong><\/li>\r\n \t<li><strong>Digestion requires energy<\/strong> \u2192 feeding intolerance<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1>Signs and Symptoms:<\/h1>\r\n<ul>\r\n \t<li><strong>Feeding difficulties<\/strong>\r\n<ul>\r\n \t<li><strong>Pulmonary edema<\/strong> makes <strong>breathing + nursing<\/strong> difficult<\/li>\r\n \t<li><strong>Poor feeding<\/strong> in infants and toddlers<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Respiratory manifestations<\/strong>\r\n<ul>\r\n \t<li><strong>Orthopnea<\/strong> (worse breathing when lying flat)<\/li>\r\n \t<li><strong>Fluid pooling in lungs<\/strong><\/li>\r\n \t<li><strong>Frequent waking<\/strong> due to dyspnea<\/li>\r\n \t<li><strong>Tripod position \/ squatting<\/strong>\r\n<ul>\r\n \t<li>Leaning forward improves <strong>breathing<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Other signs:\r\n<ul>\r\n \t<li><strong>Cough<\/strong><\/li>\r\n \t<li><strong>Rapid respirations<\/strong><\/li>\r\n \t<li><strong>Grunting<\/strong><\/li>\r\n \t<li><strong>Nasal flaring<\/strong><\/li>\r\n \t<li><strong>Wheezing<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Diagnostic findings<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Cardiomegaly<\/strong><\/li>\r\n \t<li><strong>Arterial blood gases (ABGs)<\/strong> \u2192 assess <strong>hypoxia<\/strong><\/li>\r\n \t<li><strong>Heart sounds<\/strong>\r\n<ul>\r\n \t<li><strong>Murmurs \/ swooshing<\/strong><\/li>\r\n \t<li>Causes:\r\n<ul>\r\n \t<li><strong>Valve stenosis<\/strong><\/li>\r\n \t<li><strong>Valve regurgitation<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Hemodynamic measures<\/strong>\r\n<ul>\r\n \t<li><strong>Central venous pressure (CVP)<\/strong><\/li>\r\n \t<li><strong>Pulmonary capillary wedge pressure (PCWP)<\/strong><\/li>\r\n \t<li>Assess <strong>left ventricular strength<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Clinical signs<\/strong>\r\n<ul>\r\n \t<li><strong>Hypoxia<\/strong><\/li>\r\n \t<li><strong>Cyanosis<\/strong> (blue discoloration)<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Epidemiology - FYI:<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>8 per 1,000 births<\/strong> in <strong>Canada<\/strong><\/li>\r\n \t<li>Occur early in <strong>embryogenesis (first 4 weeks)<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Risk factors:<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Alcohol exposure<\/strong><\/li>\r\n \t<li><strong>Drug exposure<\/strong><\/li>\r\n \t<li><strong>Viral infections<\/strong>\r\n<ul>\r\n \t<li><strong>Rubella (German measles)<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Sexually transmitted infections<\/strong>\r\n<ul>\r\n \t<li><strong>Syphilis<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Genetic conditions<\/strong>\r\n<ul>\r\n \t<li><strong>Down syndrome<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Maternal diabetes<\/strong><\/li>\r\n \t<li>Other developmental defects may occur:\r\n<ul>\r\n \t<li><strong>Cleft palate<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Categories of Congenital Heart Defects:<\/strong><\/h1>\r\n<h1><strong>1. Ventricular and Atrial Septal Defects:<\/strong><\/h1>\r\n<ul>\r\n \t<li><strong>Ventricular septal defect (VSD)<\/strong>\r\n<ul>\r\n \t<li><strong>Hole in interventricular septum<\/strong><\/li>\r\n \t<li>Size and location vary<\/li>\r\n \t<li>Causes <strong>left-to-right shunt<\/strong>\r\n<ul>\r\n \t<li><strong>Left ventricle = higher pressure<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Consequences:\r\n<ul>\r\n \t<li><strong>Loss of oxygenated blood<\/strong><\/li>\r\n \t<li><strong>\u2193 Stroke volume<\/strong><\/li>\r\n \t<li><strong>\u2193 Cardiac output<\/strong><\/li>\r\n \t<li><strong>Acyanotic (pink baby)<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Risk:\r\n<ul>\r\n \t<li>Pulmonary hypertension \u2192 possible <strong>shunt reversal<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li><strong>Atrial septal defect (ASD)<\/strong>\r\n<ul>\r\n \t<li><strong>Hole between atria<\/strong><\/li>\r\n \t<li><strong>Left-to-right shunt<\/strong><\/li>\r\n \t<li>Similar effects:\r\n<ul>\r\n \t<li><strong>\u2193 Stroke volume<\/strong><\/li>\r\n \t<li><strong>Acyanotic<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>2.\u00a0 Valvular Defects:<\/strong><\/h1>\r\n<ul>\r\n \t<li>Most commonly affected:\r\n<ul>\r\n \t<li><strong>Aortic valve<\/strong><\/li>\r\n \t<li><strong>Pulmonary valve<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Types:\r\n<ul>\r\n \t<li><strong>Stenosis<\/strong> (narrowing)<\/li>\r\n \t<li><strong>Incompetence \/ regurgitation<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Consequences:\r\n<ul>\r\n \t<li><strong>Heart hypertrophy<\/strong><\/li>\r\n \t<li><strong>Heart failure<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Treatment:\r\n<ul>\r\n \t<li><strong>Valve replacement<\/strong>\r\n<ul>\r\n \t<li><strong>Mechanical valve<\/strong><\/li>\r\n \t<li><strong>Bioprosthetic (pig) valve<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<strong>Mitral and Aortic Valve Prolapse (floppy valve) Regurgitation Examples<\/strong>\r\n<ol>\r\n \t<li><strong> Mitral Regurgitation (Mitral Insufficiency):<\/strong><\/li>\r\n<\/ol>\r\n<ul>\r\n \t<li><strong>Definition:<\/strong>\u00a0The\u00a0<strong>mitral valve<\/strong>\u00a0leaks, causing\u00a0<strong>blood to flow backward<\/strong>\u00a0from the\u00a0<strong>left ventricle<\/strong>\u00a0into the\u00a0<strong>left atrium<\/strong>\u00a0during ventricular contraction (systole).<\/li>\r\n \t<li><strong>Effects:<\/strong>\r\n<ul>\r\n \t<li><strong>Volume overload<\/strong>\u00a0in the\u00a0<strong>left atrium<\/strong>.<\/li>\r\n \t<li>Increased\u00a0<strong>dilation<\/strong>\u00a0and\u00a0<strong>hypertrophy<\/strong>\u00a0of the\u00a0<strong>left ventricle<\/strong>\u00a0as it compensates.<\/li>\r\n \t<li>Reduced\u00a0<strong>forward flow<\/strong>\u00a0into the systemic circulation, leading to\u00a0<strong>poor tissue and organ perfusion<\/strong>.<\/li>\r\n \t<li>Possible\u00a0<strong>pulmonary congestion<\/strong>\u00a0due to\u00a0<strong>backward flow<\/strong>\u00a0into the pulmonary veins, resulting in\u00a0<strong>pulmonary edema<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<ol start=\"2\">\r\n \t<li><strong> Aortic Regurgitation (Aortic Insufficiency):<\/strong><\/li>\r\n<\/ol>\r\n<ul>\r\n \t<li><strong>Definition:<\/strong>\u00a0The\u00a0<strong>aortic valve<\/strong>\u00a0leaks, allowing\u00a0<strong>blood to flow backward<\/strong>\u00a0from the\u00a0<strong>aorta<\/strong>\u00a0into the\u00a0<strong>left ventricle<\/strong>\u00a0during ventricular relaxation (diastole).<\/li>\r\n \t<li><strong>Effects:<\/strong>\r\n<ul>\r\n \t<li><strong>Volume overload<\/strong>\u00a0in the\u00a0<strong>left ventricle<\/strong>.<\/li>\r\n \t<li>Similar\u00a0<strong>dilation<\/strong>\u00a0and\u00a0<strong>hypertrophy<\/strong>\u00a0as the ventricle struggles to handle increased volume.<\/li>\r\n \t<li><strong>Decreased effective blood ejection<\/strong>\u00a0into systemic circulation.<\/li>\r\n \t<li>Blood\u00a0<strong>backups into the pulmonary circulation<\/strong>, causing\u00a0<strong>pulmonary edema<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<strong> Common Consequences:<\/strong>\r\n<ul>\r\n \t<li>Both <strong>mitral<\/strong> and <strong>aortic valve prolapse<\/strong> conditions <strong>reduce blood supply<\/strong>\u00a0to tissues and organs.<\/li>\r\n \t<li>The\u00a0<strong>backward flow<\/strong>\u00a0increases pressure in the pulmonary circulation.<\/li>\r\n<\/ul>\r\nThese are\u00a0<strong>potentially life-threatening<\/strong>, especially if untreated, leading to\u00a0<strong>heart failure<\/strong>.\r\n<h1>3.\u00a0 Aortic Stenosis:<\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>\u2193 Stroke volume<\/strong><\/li>\r\n \t<li><strong>\u2191 Left ventricular workload<\/strong><\/li>\r\n \t<li><strong>Pathologic hypertrophy<\/strong><\/li>\r\n \t<li>\u2192 <strong>Left-sided CHF<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>4.\u00a0 Tetralogy of Fallot (cyanotic defect):<\/strong><\/h1>\r\n<ul>\r\n \t<li><strong>Four abnormalities<\/strong>\r\n<ol>\r\n \t<li><strong>Pulmonary stenosis<\/strong><\/li>\r\n \t<li><strong>Right ventricular hypertrophy<\/strong><\/li>\r\n \t<li><strong>Ventricular septal defect<\/strong><\/li>\r\n \t<li><strong>Overriding (dextropositioned) aorta<\/strong><\/li>\r\n<\/ol>\r\n<\/li>\r\n \t<li>Pathophysiology:<\/li>\r\n<\/ul>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Right-sided pressure &gt; left<\/strong><\/li>\r\n \t<li><strong>Right-to-left shunt<\/strong><\/li>\r\n \t<li><strong>Deoxygenated blood enters systemic circulation<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<ul>\r\n \t<li>Outcome:<\/li>\r\n<\/ul>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Severe cyanosis<\/strong><\/li>\r\n \t<li><strong>\u201cBlue baby\u201d<\/strong><\/li>\r\n \t<li>Requires <strong>surgical repair<\/strong><\/li>\r\n \t<li>Often <strong>heart transplant consideration<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Acyanotic and Cyanotic Congenital Heart Defects:<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li>Progress to <strong>congestive heart failure<\/strong><\/li>\r\n \t<li>Classified as:\r\n<ul>\r\n \t<li><strong>Acyanotic (\u201cpink baby\u201d)<\/strong><\/li>\r\n \t<li><strong>Cyanotic (\u201cblue baby\u201d)<\/strong> \u2192 more severe<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Body's Compensatory Responses<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li>Activation of:\r\n<ul>\r\n \t<li><strong>Sympathetic nervous system<\/strong><\/li>\r\n \t<li><strong>Renin\u2013angiotensin system<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Results:\r\n<ul>\r\n \t<li><strong>Tachycardia<\/strong><\/li>\r\n \t<li><strong>Peripheral vasoconstriction<\/strong><\/li>\r\n \t<li><strong>Pallor \/ cyanosis<\/strong><\/li>\r\n \t<li><strong>Pulse deficit<\/strong> (apical &gt; peripheral pulse)<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Chronic Hypoxia - Signs and Symptoms:<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Dyspnea<\/strong><\/li>\r\n \t<li><strong>Squatting \/ tripod posture<\/strong><\/li>\r\n \t<li><strong>Clubbing of fingers<\/strong><\/li>\r\n \t<li><strong>Poor exercise tolerance<\/strong><\/li>\r\n \t<li><strong>Poor tolerance to temperature extremes<\/strong><\/li>\r\n \t<li><strong>Delayed growth and development<\/strong><\/li>\r\n \t<li><strong>\u2191 Erythropoietin<\/strong> \u2192 <strong>\u2191 RBC production<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1><strong>Treatment:<\/strong><\/h1>\r\n<ul>\r\n \t<li style=\"list-style-type: none\">\r\n<ul>\r\n \t<li><strong>Surgical repair<\/strong><\/li>\r\n \t<li>Some defects may <strong>self-correct<\/strong><\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<h1>Summary:<\/h1>\r\n<ul>\r\n \t<li><strong>Congenital heart defects (CHDs)<\/strong> result from <strong>abnormal heart development early in embryogenesis<\/strong> (often within the first 4 weeks of pregnancy). They affect about <strong>8 in 1,000 infants in Canada<\/strong>.<\/li>\r\n \t<li><strong>Risk factors<\/strong> include <strong>alcohol and drug exposure, viral infections (e.g., rubella), STIs (syphilis), maternal diabetes, and genetic conditions (e.g., Down syndrome)<\/strong>.<\/li>\r\n \t<li>CHDs often cause <strong>\u2193 stroke volume and \u2193 cardiac output<\/strong>, leading to <strong>congestive heart failure<\/strong>.<\/li>\r\n \t<li>Reduced cardiac output results in <strong>poor oxygen delivery<\/strong>, causing <strong>delayed growth, poor weight gain, feeding difficulties<\/strong>, and <strong>low energy for metabolism and development<\/strong>.<\/li>\r\n \t<li><strong>Respiratory signs<\/strong> include <strong>pulmonary edema, dyspnea, orthopnea, rapid respirations, grunting, wheezing, nasal flaring<\/strong>, and use of <strong>tripod or squatting positions<\/strong> to ease breathing.<\/li>\r\n \t<li><strong>Clinical findings<\/strong> may include <strong>cyanosis (blue baby) or acyanosis (pink baby)<\/strong>, <strong>tachycardia, pulse deficits, clubbing of fingers<\/strong>, and <strong>poor exercise tolerance<\/strong>.<\/li>\r\n \t<li><strong>Diagnosis<\/strong> involves detecting <strong>murmurs<\/strong>, <strong>cardiomegaly<\/strong>, <strong>hypoxia (ABGs)<\/strong>, and abnormal <strong>cardiac pressures<\/strong>.<\/li>\r\n \t<li>Untreated defects can progress to <strong>heart failure<\/strong>; many require <strong>surgical repair<\/strong>, though some may self-resolve.<\/li>\r\n \t<li><strong>Major defect categories<\/strong>:\r\n<ul>\r\n \t<li><strong>Septal defects (ASD, VSD):<\/strong> Typically cause <strong>left-to-right shunts<\/strong>, reduced effective cardiac output, and are usually <strong>acyanotic<\/strong>.<\/li>\r\n \t<li><strong>Valvular defects:<\/strong> Most commonly <strong>aortic or pulmonary stenosis or regurgitation<\/strong>, leading to <strong>hypertrophy and heart failure<\/strong>.<\/li>\r\n \t<li><strong>Tetralogy of Fallot:<\/strong> A severe <strong>cyanotic defect<\/strong> with <strong>right-to-left shunting<\/strong>, resulting in significant hypoxia and requiring <strong>urgent surgical management<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>","rendered":"<h1><strong>Congenital Heart Defect Definition:\u00a0<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Abnormal heart formation<\/strong> during <strong>embryonic development<\/strong> in the <strong>uterus<\/strong><\/li>\n<li><strong>Multiple causes<\/strong> (discussed later)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Physiological consequences:<\/strong><\/h1>\n<ul>\n<li><strong>Defective heart \u2192 decreased function<\/strong>\n<ul>\n<li><strong>\u2193 Stroke volume<\/strong><\/li>\n<li><strong>\u2193 Cardiac output<\/strong><\/li>\n<li>Meets definition of <strong>congestive heart failure (CHF)<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Physiological consequences<\/strong>\n<ul>\n<li><strong>\u2193 Oxygenated blood delivery<\/strong> to tissues<\/li>\n<li><strong>Delayed growth and development<\/strong><\/li>\n<li><strong>Poor weight gain<\/strong><\/li>\n<li><strong>\u2193 ATP production<\/strong> \u2192 impaired <strong>mitosis<\/strong><\/li>\n<li><strong>Digestion requires energy<\/strong> \u2192 feeding intolerance<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1>Signs and Symptoms:<\/h1>\n<ul>\n<li><strong>Feeding difficulties<\/strong>\n<ul>\n<li><strong>Pulmonary edema<\/strong> makes <strong>breathing + nursing<\/strong> difficult<\/li>\n<li><strong>Poor feeding<\/strong> in infants and toddlers<\/li>\n<\/ul>\n<\/li>\n<li><strong>Respiratory manifestations<\/strong>\n<ul>\n<li><strong>Orthopnea<\/strong> (worse breathing when lying flat)<\/li>\n<li><strong>Fluid pooling in lungs<\/strong><\/li>\n<li><strong>Frequent waking<\/strong> due to dyspnea<\/li>\n<li><strong>Tripod position \/ squatting<\/strong>\n<ul>\n<li>Leaning forward improves <strong>breathing<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Other signs:\n<ul>\n<li><strong>Cough<\/strong><\/li>\n<li><strong>Rapid respirations<\/strong><\/li>\n<li><strong>Grunting<\/strong><\/li>\n<li><strong>Nasal flaring<\/strong><\/li>\n<li><strong>Wheezing<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Diagnostic findings<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Cardiomegaly<\/strong><\/li>\n<li><strong>Arterial blood gases (ABGs)<\/strong> \u2192 assess <strong>hypoxia<\/strong><\/li>\n<li><strong>Heart sounds<\/strong>\n<ul>\n<li><strong>Murmurs \/ swooshing<\/strong><\/li>\n<li>Causes:\n<ul>\n<li><strong>Valve stenosis<\/strong><\/li>\n<li><strong>Valve regurgitation<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>Hemodynamic measures<\/strong>\n<ul>\n<li><strong>Central venous pressure (CVP)<\/strong><\/li>\n<li><strong>Pulmonary capillary wedge pressure (PCWP)<\/strong><\/li>\n<li>Assess <strong>left ventricular strength<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>Clinical signs<\/strong>\n<ul>\n<li><strong>Hypoxia<\/strong><\/li>\n<li><strong>Cyanosis<\/strong> (blue discoloration)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Epidemiology &#8211; FYI:<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>8 per 1,000 births<\/strong> in <strong>Canada<\/strong><\/li>\n<li>Occur early in <strong>embryogenesis (first 4 weeks)<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Risk factors:<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Alcohol exposure<\/strong><\/li>\n<li><strong>Drug exposure<\/strong><\/li>\n<li><strong>Viral infections<\/strong>\n<ul>\n<li><strong>Rubella (German measles)<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Sexually transmitted infections<\/strong>\n<ul>\n<li><strong>Syphilis<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Genetic conditions<\/strong>\n<ul>\n<li><strong>Down syndrome<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Maternal diabetes<\/strong><\/li>\n<li>Other developmental defects may occur:\n<ul>\n<li><strong>Cleft palate<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Categories of Congenital Heart Defects:<\/strong><\/h1>\n<h1><strong>1. Ventricular and Atrial Septal Defects:<\/strong><\/h1>\n<ul>\n<li><strong>Ventricular septal defect (VSD)<\/strong>\n<ul>\n<li><strong>Hole in interventricular septum<\/strong><\/li>\n<li>Size and location vary<\/li>\n<li>Causes <strong>left-to-right shunt<\/strong>\n<ul>\n<li><strong>Left ventricle = higher pressure<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Consequences:\n<ul>\n<li><strong>Loss of oxygenated blood<\/strong><\/li>\n<li><strong>\u2193 Stroke volume<\/strong><\/li>\n<li><strong>\u2193 Cardiac output<\/strong><\/li>\n<li><strong>Acyanotic (pink baby)<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Risk:\n<ul>\n<li>Pulmonary hypertension \u2192 possible <strong>shunt reversal<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>Atrial septal defect (ASD)<\/strong>\n<ul>\n<li><strong>Hole between atria<\/strong><\/li>\n<li><strong>Left-to-right shunt<\/strong><\/li>\n<li>Similar effects:\n<ul>\n<li><strong>\u2193 Stroke volume<\/strong><\/li>\n<li><strong>Acyanotic<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>2.\u00a0 Valvular Defects:<\/strong><\/h1>\n<ul>\n<li>Most commonly affected:\n<ul>\n<li><strong>Aortic valve<\/strong><\/li>\n<li><strong>Pulmonary valve<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Types:\n<ul>\n<li><strong>Stenosis<\/strong> (narrowing)<\/li>\n<li><strong>Incompetence \/ regurgitation<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Consequences:\n<ul>\n<li><strong>Heart hypertrophy<\/strong><\/li>\n<li><strong>Heart failure<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Treatment:\n<ul>\n<li><strong>Valve replacement<\/strong>\n<ul>\n<li><strong>Mechanical valve<\/strong><\/li>\n<li><strong>Bioprosthetic (pig) valve<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><strong>Mitral and Aortic Valve Prolapse (floppy valve) Regurgitation Examples<\/strong><\/p>\n<ol>\n<li><strong> Mitral Regurgitation (Mitral Insufficiency):<\/strong><\/li>\n<\/ol>\n<ul>\n<li><strong>Definition:<\/strong>\u00a0The\u00a0<strong>mitral valve<\/strong>\u00a0leaks, causing\u00a0<strong>blood to flow backward<\/strong>\u00a0from the\u00a0<strong>left ventricle<\/strong>\u00a0into the\u00a0<strong>left atrium<\/strong>\u00a0during ventricular contraction (systole).<\/li>\n<li><strong>Effects:<\/strong>\n<ul>\n<li><strong>Volume overload<\/strong>\u00a0in the\u00a0<strong>left atrium<\/strong>.<\/li>\n<li>Increased\u00a0<strong>dilation<\/strong>\u00a0and\u00a0<strong>hypertrophy<\/strong>\u00a0of the\u00a0<strong>left ventricle<\/strong>\u00a0as it compensates.<\/li>\n<li>Reduced\u00a0<strong>forward flow<\/strong>\u00a0into the systemic circulation, leading to\u00a0<strong>poor tissue and organ perfusion<\/strong>.<\/li>\n<li>Possible\u00a0<strong>pulmonary congestion<\/strong>\u00a0due to\u00a0<strong>backward flow<\/strong>\u00a0into the pulmonary veins, resulting in\u00a0<strong>pulmonary edema<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ol start=\"2\">\n<li><strong> Aortic Regurgitation (Aortic Insufficiency):<\/strong><\/li>\n<\/ol>\n<ul>\n<li><strong>Definition:<\/strong>\u00a0The\u00a0<strong>aortic valve<\/strong>\u00a0leaks, allowing\u00a0<strong>blood to flow backward<\/strong>\u00a0from the\u00a0<strong>aorta<\/strong>\u00a0into the\u00a0<strong>left ventricle<\/strong>\u00a0during ventricular relaxation (diastole).<\/li>\n<li><strong>Effects:<\/strong>\n<ul>\n<li><strong>Volume overload<\/strong>\u00a0in the\u00a0<strong>left ventricle<\/strong>.<\/li>\n<li>Similar\u00a0<strong>dilation<\/strong>\u00a0and\u00a0<strong>hypertrophy<\/strong>\u00a0as the ventricle struggles to handle increased volume.<\/li>\n<li><strong>Decreased effective blood ejection<\/strong>\u00a0into systemic circulation.<\/li>\n<li>Blood\u00a0<strong>backups into the pulmonary circulation<\/strong>, causing\u00a0<strong>pulmonary edema<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><strong> Common Consequences:<\/strong><\/p>\n<ul>\n<li>Both <strong>mitral<\/strong> and <strong>aortic valve prolapse<\/strong> conditions <strong>reduce blood supply<\/strong>\u00a0to tissues and organs.<\/li>\n<li>The\u00a0<strong>backward flow<\/strong>\u00a0increases pressure in the pulmonary circulation.<\/li>\n<\/ul>\n<p>These are\u00a0<strong>potentially life-threatening<\/strong>, especially if untreated, leading to\u00a0<strong>heart failure<\/strong>.<\/p>\n<h1>3.\u00a0 Aortic Stenosis:<\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>\u2193 Stroke volume<\/strong><\/li>\n<li><strong>\u2191 Left ventricular workload<\/strong><\/li>\n<li><strong>Pathologic hypertrophy<\/strong><\/li>\n<li>\u2192 <strong>Left-sided CHF<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>4.\u00a0 Tetralogy of Fallot (cyanotic defect):<\/strong><\/h1>\n<ul>\n<li><strong>Four abnormalities<\/strong>\n<ol>\n<li><strong>Pulmonary stenosis<\/strong><\/li>\n<li><strong>Right ventricular hypertrophy<\/strong><\/li>\n<li><strong>Ventricular septal defect<\/strong><\/li>\n<li><strong>Overriding (dextropositioned) aorta<\/strong><\/li>\n<\/ol>\n<\/li>\n<li>Pathophysiology:<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Right-sided pressure &gt; left<\/strong><\/li>\n<li><strong>Right-to-left shunt<\/strong><\/li>\n<li><strong>Deoxygenated blood enters systemic circulation<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<ul>\n<li>Outcome:<\/li>\n<\/ul>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Severe cyanosis<\/strong><\/li>\n<li><strong>\u201cBlue baby\u201d<\/strong><\/li>\n<li>Requires <strong>surgical repair<\/strong><\/li>\n<li>Often <strong>heart transplant consideration<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Acyanotic and Cyanotic Congenital Heart Defects:<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li>Progress to <strong>congestive heart failure<\/strong><\/li>\n<li>Classified as:\n<ul>\n<li><strong>Acyanotic (\u201cpink baby\u201d)<\/strong><\/li>\n<li><strong>Cyanotic (\u201cblue baby\u201d)<\/strong> \u2192 more severe<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Body&#8217;s Compensatory Responses<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li>Activation of:\n<ul>\n<li><strong>Sympathetic nervous system<\/strong><\/li>\n<li><strong>Renin\u2013angiotensin system<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Results:\n<ul>\n<li><strong>Tachycardia<\/strong><\/li>\n<li><strong>Peripheral vasoconstriction<\/strong><\/li>\n<li><strong>Pallor \/ cyanosis<\/strong><\/li>\n<li><strong>Pulse deficit<\/strong> (apical &gt; peripheral pulse)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Chronic Hypoxia &#8211; Signs and Symptoms:<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Dyspnea<\/strong><\/li>\n<li><strong>Squatting \/ tripod posture<\/strong><\/li>\n<li><strong>Clubbing of fingers<\/strong><\/li>\n<li><strong>Poor exercise tolerance<\/strong><\/li>\n<li><strong>Poor tolerance to temperature extremes<\/strong><\/li>\n<li><strong>Delayed growth and development<\/strong><\/li>\n<li><strong>\u2191 Erythropoietin<\/strong> \u2192 <strong>\u2191 RBC production<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1><strong>Treatment:<\/strong><\/h1>\n<ul>\n<li style=\"list-style-type: none\">\n<ul>\n<li><strong>Surgical repair<\/strong><\/li>\n<li>Some defects may <strong>self-correct<\/strong><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h1>Summary:<\/h1>\n<ul>\n<li><strong>Congenital heart defects (CHDs)<\/strong> result from <strong>abnormal heart development early in embryogenesis<\/strong> (often within the first 4 weeks of pregnancy). They affect about <strong>8 in 1,000 infants in Canada<\/strong>.<\/li>\n<li><strong>Risk factors<\/strong> include <strong>alcohol and drug exposure, viral infections (e.g., rubella), STIs (syphilis), maternal diabetes, and genetic conditions (e.g., Down syndrome)<\/strong>.<\/li>\n<li>CHDs often cause <strong>\u2193 stroke volume and \u2193 cardiac output<\/strong>, leading to <strong>congestive heart failure<\/strong>.<\/li>\n<li>Reduced cardiac output results in <strong>poor oxygen delivery<\/strong>, causing <strong>delayed growth, poor weight gain, feeding difficulties<\/strong>, and <strong>low energy for metabolism and development<\/strong>.<\/li>\n<li><strong>Respiratory signs<\/strong> include <strong>pulmonary edema, dyspnea, orthopnea, rapid respirations, grunting, wheezing, nasal flaring<\/strong>, and use of <strong>tripod or squatting positions<\/strong> to ease breathing.<\/li>\n<li><strong>Clinical findings<\/strong> may include <strong>cyanosis (blue baby) or acyanosis (pink baby)<\/strong>, <strong>tachycardia, pulse deficits, clubbing of fingers<\/strong>, and <strong>poor exercise tolerance<\/strong>.<\/li>\n<li><strong>Diagnosis<\/strong> involves detecting <strong>murmurs<\/strong>, <strong>cardiomegaly<\/strong>, <strong>hypoxia (ABGs)<\/strong>, and abnormal <strong>cardiac pressures<\/strong>.<\/li>\n<li>Untreated defects can progress to <strong>heart failure<\/strong>; many require <strong>surgical repair<\/strong>, though some may self-resolve.<\/li>\n<li><strong>Major defect categories<\/strong>:\n<ul>\n<li><strong>Septal defects (ASD, VSD):<\/strong> Typically cause <strong>left-to-right shunts<\/strong>, reduced effective cardiac output, and are usually <strong>acyanotic<\/strong>.<\/li>\n<li><strong>Valvular defects:<\/strong> Most commonly <strong>aortic or pulmonary stenosis or regurgitation<\/strong>, leading to <strong>hypertrophy and heart failure<\/strong>.<\/li>\n<li><strong>Tetralogy of Fallot:<\/strong> A severe <strong>cyanotic defect<\/strong> with <strong>right-to-left shunting<\/strong>, resulting in significant hypoxia and requiring <strong>urgent surgical management<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"author":1370,"menu_order":36,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["zoe-soon"],"pb_section_license":"cc-by-nc-sa"},"chapter-type":[],"contributor":[60],"license":[57],"class_list":["post-5675","chapter","type-chapter","status-web-only","hentry","contributor-zoe-soon","license-cc-by-nc-sa"],"part":55,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5675","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/users\/1370"}],"version-history":[{"count":6,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5675\/revisions"}],"predecessor-version":[{"id":5681,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5675\/revisions\/5681"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/parts\/55"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5675\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/media?parent=5675"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapter-type?post=5675"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/contributor?post=5675"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/license?post=5675"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}