Ventricular Septal Defect (VSD)

Overview

Definition

A ventricular septal defect Ventricular Septal Defect Tetralogy of Fallot (VSD) is a malformation of the interventricular septum (IVS) resulting in an abnormal communication Communication The exchange or transmission of ideas, attitudes, or beliefs between individuals or groups. Decision-making Capacity and Legal Competence between the left ventricle (LV) and the right ventricle (RV). This defect may present in isolation, or be a part of another anomaly, such as tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot.

Classification

There are 4 main subtypes of VSD based on location along IVS:

1. Membranous (75% of cases):
   • Also called perimembranous or conoventricular
   • Most common subtype
   • Located at distal conal septum (just inferior to aortic valve Aortic valve The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle. Heart: Anatomy)
   • In proximity to bundle of His Bundle of His Small band of specialized cardiac muscle fibers that originates in the atrioventricular node and extends into the membranous part of the interventricular septum. The bundle of his, consisting of the left and the right bundle branches, conducts the electrical impulses to the heart ventricles in generation of myocardial contraction. Heart: Anatomy
2. Muscular (20%):
   • Located along trabeculated muscular septum
   • Classified as anterior, mid-muscular, apical, or posterior
   • Common in premature infants Premature infants A human infant born before 37 weeks of gestation. Sudden Infant Death Syndrome (SIDS)
   • May be multiple
   • Most likely to undergo spontaneous closure
3. Inlet (5%):
   • Also called AV canal defect
   • Located around tricuspid annulus (inlet)
   • Always accompanies other endocardial cushion Endocardial cushion A fetal heart structure that is the bulging areas in the cardiac septum between the heart atria and the heart ventricles. During development, growth and fusion of endocardial cushions at midline forms the two atrioventricular canals, the sites for future tricuspid valve and bicuspid valve. Development of the Heart defects
   • Will not close spontaneously
4. Supracristal (5%):
   • Also called outlet defect
   • Located inferior to pulmonic valve at right ventricular outflow tract
   • More common in Asian population
   • Will not close spontaneously

Epidemiology

• The most common congenital Congenital Chorioretinitis heart defect (CHD): 25% of all CHDs
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: 5–50/1,000 live births
• Increased risk:
  • Family history Family History Adult Health Maintenance: 3x increase
  • Maternal factors:
    • Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity
    • Diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus
    • Alcohol use → muscular VSD

Etiology

Exact mechanism is unknown. Genetic syndromes:

• Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21) ( Trisomy 21 Trisomy 21 Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down syndrome (Trisomy 21))
• Patau’s syndrome ( Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 13)
• Edwards’ syndrome ( Trisomy Trisomy The possession of a third chromosome of any one type in an otherwise diploid cell. Types of Mutations 18)

Pathophysiology and Clinical Presentation

Pathophysiology

Physiologic changes occur based on the size of the defect and the resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing across which the blood has to flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure.

• Small VSD:
  • < 4 mm
  • Minimal left-to-right shunting due to high resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing within defect
  • Maintains RV pressure to normal
  • Rarely causes heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR)
• Moderate VSD:
  • 4–6 mm
  • Left-to-right shunt
  • Higher resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing (smaller defect) → pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy pressure < 50% of systemic pressure → least amount of change within ventricles and pulmonary circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  • Lower resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing (larger defect) → pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy pressure is > 50% of systemic pressure → pulmonary congestion and LV remodeling
• Large VSD:
  • > 6 mm
  • Very little resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing to flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure across defect
  • Left-to-right shunt equalizes pressure between RV and LV
  • After birth, as fetal pulmonary vascular resistance Resistance Physiologically, the opposition to flow of air caused by the forces of friction. As a part of pulmonary function testing, it is the ratio of driving pressure to the rate of air flow. Ventilation: Mechanics of Breathing (PVR) decreases → increased pulmonary blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure → pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension → RV hypertrophy Hypertrophy General increase in bulk of a part or organ due to cell enlargement and accumulation of fluids and secretions, not due to tumor formation, nor to an increase in the number of cells (hyperplasia). Cellular Adaptation
  • Eisenmenger’s syndrome can occur once RV pressure is higher → right-to-left shunting and cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination

Clinical presentation

Age of presentation is usually around 2 months, unless a larger defect is present which becomes symptomatic within weeks of birth.

• Small VSD:
  • Usually asymptomatic
  • Incidental murmur
• Moderate/large VSD:
  • Poor feeding (sweating or fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia)
  • Poor weight gain
  • Shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Recurrent lung infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease
  • Infective endocarditis Infective endocarditis Infective endocarditis (IE) is caused by infection or inflammation of the inner lining of the heart (endocardium), most commonly affecting the heart valves. Endocarditis

Diagnosis

Physical examination

• General appearance:
  • Pallor
  • Failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive
• Precordial exam:
  • Displaced apex
  • Systolic thrill
  • Murmur:
    • Small VSD:
      • Harsh holosystolic
      • Grade 2 or 3
      • Left lower sternal border
    • Large VSD:
      • Systolic murmur with diastolic rumble (apex)
      • No murmur, if severe
• Signs of respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure:
  • Tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination
  • Grunting Grunting Physical Examination of the Newborn
  • Nasal flaring
  • Retraction
  • Hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage
• Signs of heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR):
  • Hepatomegaly
  • Tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children
  • S3 S3 Heart Sounds and S4 S4 Heart Sounds heart sounds Heart sounds Heart sounds are brief, transient sounds produced by valve opening and closure and by movement of blood in the heart. They are divided into systolic and diastolic sounds. In most cases, only the first (S1) and second (S2) heart sounds are heard. These are high-frequency sounds and arise from aortic and pulmonary valve closure (S1), as well as mitral and tricuspid valve closure (S2). Heart Sounds

Imaging

• Echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA) with color doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography): 
  • Confirmatory (can be done prenatally)
  • Evaluates:
    • Type and location
    • Size of defect
    • Extent of left-to-right shunt
    • Pulmonary arterial pressure Pulmonary Arterial Pressure Pulmonary Hypertension Drugs
• Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
  • Increased pulmonary vascularization
  • Cardiomegaly Cardiomegaly Enlargement of the heart, usually indicated by a cardiothoracic ratio above 0. 50. Heart enlargement may involve the right, the left, or both heart ventricles or heart atria. Cardiomegaly is a nonspecific symptom seen in patients with chronic systolic heart failure (heart failure) or several forms of cardiomyopathies. Ebstein’s Anomaly
• ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG):
  • Normal in smaller defects
  • Moderate-to-large defects may show LV and RV hypertrophy Hypertrophy General increase in bulk of a part or organ due to cell enlargement and accumulation of fluids and secretions, not due to tumor formation, nor to an increase in the number of cells (hyperplasia). Cellular Adaptation

Management

Management

The management of a VSD is based on the size of the defect and the clinical symptoms of the patient.

• Small VSD/asymptomatic infant:
  • Re-evaluate every 2 years, if murmur present.
  • Follow up yearly to assess development of symptoms.
  • Majority will close spontaneously.
• Asymptomatic moderate-to-large VSD:
  • Regular Regular Insulin follow-up with echocardiogram Echocardiogram Transposition of the Great Vessels to assess hemodynamic stability.
  • Surgically repair once LV dilation occurs.
• Symptomatic patient:
  • Mild:
    • Adequate growth with mild tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination
    • Medical management
  • Moderate:
    • Signs of failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive
    • Medical management with caloric intake
    • Bridge to surgical repair
  • Severe:
    • Symptoms of heart and/or respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure
    • Inpatient medical stabilization followed by immediate surgical repair
• Medical management:
  • Nutritional support
  • Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR) → diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication
  • Up-to-date vaccines
• Surgical management involves repairing defect with patch Patch Nonpalpable lesion > 1 cm in diameter Generalized and Localized Rashes, usually before age of 1.

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

• Excellent long-term survival
• Majority of small and asymptomatic moderate VSD spontaneously close.
• Complications post-surgical repair are rare

Clinical Relevance

The following conditions are associated with VSD and can cause or modify the disease:

• Heart failure Heart Failure A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (ventricular dysfunction), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as myocardial infarction. Total Anomalous Pulmonary Venous Return (TAPVR): large VSD may result in severe left-to-right shunt causing reduced LV stroke volume Stroke volume The amount of blood pumped out of the heart per beat, not to be confused with cardiac output (volume/time). It is calculated as the difference between the end-diastolic volume and the end-systolic volume. Cardiac Cycle, plus higher cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics from RV. This leads to pulmonary congestion and eventually right-sided heart failure Right-Sided Heart Failure Ebstein’s Anomaly.
• Failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive: suboptimal weight gain Suboptimal Weight Gain Failure to Thrive and growth in children. As with majority of CHDs, 1st presentation of VSD may be infant or child failing to meet necessary caloric requirement for growth due to increased demand of overworking heart.
• Endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis: growth of infectious vegetations on endothelium Endothelium A layer of epithelium that lines the heart, blood vessels (vascular endothelium), lymph vessels (lymphatic endothelium), and the serous cavities of the body. Arteries: Histology of heart. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with VSDs are at increased risk of developing it.
• Aortic insufficiency: inability of AV to remain shut during diastole Diastole Post-systolic relaxation of the heart, especially the heart ventricles. Cardiac Cycle, causing reversed flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure into LV. Due to low-pressure zone created in LV through VSD, AV prolapses and becomes insufficient.