Congenital Heart Defects

Causes of CHF in CHD

1. Pulmonary Volume Overload - Too much blood flow 2. Pulmonary Venous Congestion - Left Side Obstruction Prevent Lung Draining

Atrial Septum Formation

1. Septum Primum descends from the top of the Atrium and the space below it is termed the Ostium Primum 2. The Septum Primum extends downward into the Endocardial Cushion (causing the Ostium Primum to disappear) and the Ostium Secundum forms near the top of the Septum Primum 3. The Septum Secundum extends downward, midway through the Atrium and below it is the Foramen Ovale

Anomalies Assoicated with Tetralogy of Fallot

1. Ventricular Septa Defect due to Septum Misalignment 2. Subvalvular Pulmonic Stenosis because of obstruction of the Infundibular Septum 3. An overriding (dextroposed) aorta that receives blood from both ventricles. 4. Right ventricular hypertrophy due to the high pressure load of the pulmonic stenosis.

Abbot Classification Groups

ACYANOTIC - Does not have abnormal communication between the two cirulations CYANOTIC - There is a permanent Right-to-Left shunt CYANOSE TARDIVE - An initial Left-to-Right shunt with late reversal of flow

How does squatting relieve Cyanosis?

ARTERIAL SYSTEM: Increased arterial resistance = Increased Aortic Pressure = Increased Ventricular Pressure = Increased Oxygenated Blood Flow = Decreased cyanosis VENOUS SYSTEM: Decreased venous return = Decreased blood to Right Ventricle = Decreased Deoxygenated blood sent to Left Ventricle = Decreased Cyanosis

Cause of Too Little Pulmonary Flow

An obstruction of flow into or out of the Right Ventricle (Tetrology of Fallot)

Transposition of the Great Arteries

Aorta originates from the Right Ventricle and Pulmonary Artery originates from the Left Ventricle. Creates two circulations that, instead of being in series, are in parallel. The Embryonic veins bring blood to the Right Atrium, it goes to the Right Ventricle and is pumped right back out into the Aorta. The left atrium meanwhile receives blood from the Pulmonary veins, gives it to the Left Ventricle, which pumps it back to the lungs via the Pulmonary Trunk.

Too Little Pulmonary Flow - Cause, Effect, Symptom

CAUSE: Anomalies that restrict Pulmonary Flow (Tetrology of Fallot) EFFECT: Systemic Hypoxemia SYMPTOM: Cyanosis, Polycythemia (Increased HCT) and Finger Clubbing, Brain Strokes/Abscesses (Blood is too thick)

Postductal Coractation - Cause, Effect, Symptoms

CAUSE: Develops postnatally. Likely the result of muscular ductal tissue extending into the aorta during fetal life. When the ductal tissue constricts, following birth, the ectopic tissue within the aorta also constrict. EFFECT: Blood flows from the Aorta into the Pulmonary Trunk SYMPTOMS: Differential Upper Limb/Lower Limb Blood Pressures, CHF if sever

Preductual Coractation - Cause, Effect, Symptoms

CAUSE: Occurs when an Intracardiac anomaly during fetal life decreases blood flow through the left side of the heart and Aortic Isthmus, resulting in hypoplastic development of the Aorta EFFECT: Reduced Aorta Blood Pressure following the Coarctation results in blood flow from the Pulmonary Artery to the Aorta, resulting in the blood that reaches the lower limbs having a lower Oxygen concentration SYMPTOMS: Differential Upper Limb/Lower Limb Blood Pressures, Lower Limb Cyanosis, Congestive Heart Failure

Two Clinical Consequences of CHDs

CHF Systemic Hypoxia

Classifications of Congential Heart Diseases - Two Major Categories and Causes for Each

CYANOTIC - Reduced Pulmonary Flow or Mixing of Oxygenated and Deoxygenated Blood ACYANOTIC - Increased Pulmonary Blood Flow or Obstruction of Blood Flow from Ventricles

Mechanism By Which Pulmonary Venous Congestion Occurs in Coarctation of the Aorta

Coarctation of the Aorta impedes blood flow out of the Aorta → Left End Diastolic Ventricular Pressure is Elevated → Left Ventricular Hypertrophy Develops → Elevation of Atrial Pressure → Elevation of Pulmonary Venous Pressure ??

Transposition of the Great Arteries Symptoms

Compatible with life in uterus as the Ductus Arteriosus and Foramen Ovale allow for mixing of deoxygenated blood and oxygenated blood. After birth though, these will close and the baby will die. The only chance at survival requires either an Atrial Septal Defect, a Ventricular Septum Defect or a Patent Ductus Arteriosus. You could also give the baby Prostaglandins so as to keep its Ductus Arteriosus open.

Tetralogy of Fallot - Definition, Mechanism, Shunt

DEFINITION: A group of cardiac malformations that result from a single defect. MECHANISM: During looping, the aorta invades the space of the pulmonary trunk, resulting in narrowing of the latter. The cushions then do not close correctly, causing a ventricular septal defect. SHUNT: Right-to-Left Shunt because not enough blood can be pushed out through the Pulmonary Valve and the Aorta accepts blood from both Ventricles

Ventriular Septal Defect - Definition, Types, Shunt, Symptoms

DEFINITION: Abnormal opening in the Ventricular Septum TYPES: Membranous - Most Common Muscular - Due to reabsorption of a portion of the muscular wall SHUNT: Left to Right SYMPTOMS: Asymptomatic if small but CHF if large due to Left-Heart Volume Overload

Atrial Septal Defect - Definition, Types, Shunt

DEFINITION: An opening in the Atrial Septum TYPES: Ostium Secundum Ostium Primum Sinus Venosus Defect SHUNT: Left-to-Right

Persistent of Truncus Arteriosus - Definition, Type, Cause

DEFINITION: Incomplete partitioning of the truncus arterioles by the spiral septum, thus leaving a common trunk for the origin of the aorta, pulmonary arteries and coronary arteries. TYPE: Type 1 is the most common and is the definition of the disease. CAUSE: Neural Crest Cell Defect

Coarctation of Aorta and Types

DEFINITION: Pathologic narrowing of the aortic lumen that can occur anywhere along its length SYMPTOMS: Hypertension in Upper Limbs; Hypotension in Lower Limbs; Possible Lower Limb Cyanosis TYPES: If there is a Patent Ductus Ateriosus, it is either a Preductal or Postductal Coarctation

Tetralogy of Fallot Symptoms

Dyspnea on exertion or when crying Passes out following exertion or feeding Convulsions due to Cerebral Hypoxemia Children alleviate symptoms by squatting

Ductus Arteriosus (Fetus vs. Newborn)

FETUS - Ductus Arteriosus allows for communication between the Pulmonary Trunk and Aorta. Blood from the Pulmonary Trunk can go into the Aorta, allowing it to bypass the fluid-filled lungs (Right-to-Left) NEWBORN - Ductus Arteriosus closes and becomes the Ligamentum Arteriosum

Systemic Venous Congestion Signs and Symptoms

Hepatomegaly (due to blood back up) Liver Tenderness Lower Extremity Edema Pleural Effusions Weight Gain in Child Distended Neck Veins

Common Features of CHD

History of early onset of cardiac symptoms Loud murmur with a thrill along the left sternal border (rushing of blood in the arteries?) Cyanosis with intense dyspnea on exertion early in childhood Failure of normal growth and development Rapid heart rate Pulmonary wheezing

Pharmacological Regulation of Ductus Arteriosus Closure

INDOMETHACIN - Antagonist of Prostaglandins, given to cause closure of Ductus Arteriosus PROSTAGLANDINS - Can prevent closure of the Ductus Arteriosus if the shunt is actually life-saving

Classication According to the Presence of Shunt

INITIAL LEFT-TO-RIGHT - Ventricular Septal Defect, Atrial Septal Defect, Patent Ductus Arteriosus, Persistent Trunus Arteriosus RIGHT-TO-LEFT - Tetralogy of Fallo NO SHUNT - Transposition of Great Vessels, Coarctation of the Aorta, Pulmonary Stenosis, Aortic Stenosis

Fetal vs. Newborn Ductus Arteriousus Blood Flow

In the fetus, the Ductus Arteriosus allows from blood flow from the Pulmonary Trunk to the Aorta. In newborns, however, because the pressure in the Aorta is higher, it causes blood flow from the Aorta to Pulmonary trunk, not the other way around.

Normal Heart Pressures

Left Atrium > Right Atrium Left Ventricle > Right Ventricle

Life-Threatening or Life Saving

Life-Threatening - Causes Congestive Heart Failure Life Saving - Slow closure of the Ductus Arteriosus shows symptoms of another Congensital Heart Defect (ex. Transposition of Great Arteries) that would otherwise have been fatal

Mechanisms for Faulty Embryonic Development

Misplaced structures Arrest in the progression of a normal structure from an early stage to a more advanced one

Mechanism By Which Pulmonary Volume Overload Occurs with a PDA

PDA causes excessive Pulmonary Venous Return → Left Ventricle volume overload → Ventricle fails to empty completely → Elevation of Ventricular End Diastolic Pressure → Increased pressure transmitted to Left Atrium Left Atrial filling pressure increases → Pulmonary Venous Hypertension occurs ??

PTA vs. TGA

PTA - Absence of Neural Crest Cells results in the failure of the Aorticopulmonary Septum to form TGA - Neural Crest Cells are present but there is a failure of Spiralization of the Aorticopulmonary Septum

Ostium Primum

Portion of Septum Primum is missing, causing loss of the valve for the Foramen Ovale

Ostium Secundum

Portion of Septum Secundum is missing, creating an Ostium Secundum that is too large; MOST COMMON

[Ventriular Septal Defect Heart Pressures and O2 Sat]

Pressure in Left Ventricle is lowered and Pressure in Right Ventricle is heightened. Because the Right Ventricle is receiving Oxygenated blood from the Left Ventricle, the O2 Saturation is increased to 85% in the Right Venticle

Closure of Ductus Arteriosus

Prostaglandins are keeping the Ductus Arteriosus open. When the lungs inflate, High O2 causes release of Bradykinin that causes constriction of the vessels.

Pulmonary Edema

Pulmonary Hypertension also results in increasted Hydrostatic Pressure, pushing fluid out of Pulmonary Capillaries and into the Interstitial Space/Alveoli. The Veins and Lymphatic Ducts do not have the capacity to reabsorb all of this fluid, allowing Edema to be established.

[Ventriular Septal Defect X-Ray]

Pulmonary vessels and Left Atrium will be enlarged

Pathophysiology and Causes of Pulmonary Volume Overload

Putting too much blood into the arterial system of the lungs increases blood pressure, causing the Pulmonary System to become Hypertension CAUSES: Left-to-Right Shunts, including Post-Ductal PDA, ASD and VSD

Cyanosis

Results when the blood contains more than 5 grams of reduced Hb/100 mL. Recognizable by bluish tinge to the skin in areas with dense superficial capillary circulation.

Patent Ductus Arteriosus Symptoms

SMALL PDAS - Asymptomatic LARGE PDAS - Congestive Heart Failure, murmur

Coarctation of the Aorta with Closed Ductus Arteriosus

SYMPTOMS: Differential Blood Pressures based on where the Coarctation is (if in-between the Brachiocephalic and Left Subclavian, the Left Arm would be Hypotensive like the lower limbs)

Etiology of Congenital Heart Defects

Single Gene Defect Environmental Factors Maternal Ingestion of Toxic Substances (Lithium, Alcohol) Viral Exposure Unknown

Congenital Heart Defects

Structural abnormalities of the heart that are present at birth that may result in alteration of heart function

Foramen Ovale

Structure present in the fetus that allows for blood flow from the Right Atrium into the Left Atrium

Congestive Heart Failure - Groups of Signs and Symptoms

Symptoms stem from: Impaired Myocardial Function Pulmonary Congestion Systemic Venous Congestion

Impaired Myocardial Function Signs and Symptoms

Tachycardia Ventricular Dilation Extra Heart Sounds Diaphoresis Easily Fatigued Poor Exercise Tolerance and Irritability Poor Cardiac Output: Weak Pulse, Low BP

Pulmonary Congestion Signs and Symptoms

Tachypnea Hypoxia Dyspnea Inability to Feed Orthopnea Costal Retractions Wheezing, Rales

Causes of Systemic Hypoxemia in CHD and Examples

Too little Pulmonary Flow --> Tetrology of Fallot No Pulmonary-Systemic Exchange of Blood --> Transposition of Great Arteries

Sinus Venosus

Tops of Septum Secundum and Septum Primum are missing

If Cyanosis is severe at birth or soon after, it suggests:

Transposition of the Great Vessels Tetralogy of Fallot Tricuspid Atresia Severe Septal Defect Sever Pulmonary Stenosis

What are the most common anomalies?

Ventricular Septal Defect = 25-30% Atrial Septal Defect = 10-15% Patent Ducturs Arteriosus = 10-20%

Patent Ductus Arteriosus

When the Ductus Arteriosus fails to close after birth, resulting in a persistent connection between the aorta and the pulmonary trunk; higher pressure in the Aorta results in in a Left-to-Right Shunt [More common in females; associated with maternal Rubella Infection]

Consequences of Pulmonary Hypertension

With respect to the Pulmonary Arteries, in early stages the Muscularis becomes thicker, and in later stages, there is Interstitial Fibrosis. This increases the Diffusion Distance of Oxygen, resulting in RBC's passing near the Alveoli picking up less Oxygen. Fibrosis is irreversible so that even if the defect is fixed, the damage is done and transplants are required