Tetrology of Fallot in an infant - Nursing Case Study
Pathophysiology
• Primary mechanism: Tetralogy of Fallot is characterized by four heart defects. The most important is a ventricular septal defect (VSD), a hole in the wall separating the two lower heart chambers. This allows oxygen-poor blood to mix with oxygen-rich blood, reducing the overall oxygen supply.
• Secondary mechanism: Another crucial defect is pulmonary stenosis, a narrowing of the pulmonary valve and outflow tract or area below the valve, which obstructs blood flow from the right ventricle to the pulmonary artery. This increases pressure in the right heart chamber and forces more deoxygenated blood into the left heart chamber.
• Key complication: If untreated, these defects can lead to cyanosis (blue skin from lack of oxygen), heart failure, and other complications such as arrhythmias and endocarditis. Early surgical intervention can significantly improve the prognosis.
Patient Profile
Demographics:
6 months old, Male, Infant
History:
• Key past medical history: Born with Tetralogy of Fallot, no surgical intervention yet
• Current medications: Diuretics for heart failure management, Propranolol to control symptoms of Tet spells
• Allergies: No known allergies
Current Presentation:
• Chief complaint: Cyanosis, Difficulty in feeding, Rapid breathing
• Key symptoms: Increasing cyanosis especially during feeding or crying, poor weight gain, fatigue, sweating, irregular heartbeats
• Vital signs: Increased heart rate (150 bpm), Low oxygen saturation level (80%), Rapid respiratory rate (40 breaths per minute), Low body weight (6 kg for a 6-month-old baby), Normal body temperature
Section 1
Change in Patient Status:
The baby's cyanosis has noticeably worsened, now appearing even without crying or feeding. His breathing has become increasingly labored, with a respiratory rate of 50 breaths per minute, and his oxygen saturation has dropped to 75%. Furthermore, the baby has become lethargic and is showing signs of poor perfusion such as cool extremities and delayed capillary refill of 3 seconds. The baby's heart rate remains elevated at 155 bpm, and new intermittent periods of bradycardia have been noted, possibly indicating worsening heart failure or the onset of arrhythmias.
The infant's worsening condition and signs of poor perfusion suggest that his Tet spells are becoming more severe and frequent, likely due to the progressive narrowing of his pulmonary valve and outflow tract. This clinical picture indicates an urgent need for surgical intervention to correct the defects, as the baby's body is increasingly unable to compensate for the lack of oxygenated blood. The medical team must also be vigilant for the development of any new complications, such as endocarditis or brain abscess, which can arise due to the continuous flow of deoxygenated blood into the systemic circulation.
Section 2
New Diagnostic Results:
The infant's latest echocardiogram confirms the initial diagnosis of Tetralogy of Fallot and reveals significant pulmonary stenosis and a large ventricular septal defect. These findings correlate with the baby's worsening cyanosis and increased work of breathing. His blood gas analysis shows a PaO2 of 50 mmHg, indicating severe hypoxemia, and his hematocrit has risen to 65%, suggesting the body's attempt to compensate for chronic hypoxia by producing more red blood cells.
An EKG presents with signs of right ventricular hypertrophy, consistent with the baby's structural heart defects, and intermittent periods of bradycardia, which might be due to increasing heart failure or the onset of arrhythmias. These diagnostic results, along with the baby's deteriorating clinical status, support the urgency for surgical intervention. The medical team needs to engage in collaborative, multidisciplinary planning for the impending surgery while continuing to monitor for further deterioration or new complications.
Section 3
Change in Patient Status:
The infant's condition continues to deteriorate, despite the attempts to stabilize him in preparation for surgery. His oxygen saturation levels have fallen to 75%, and he has become increasingly lethargic. His breathing is labored, with intercostal and subcostal retractions, and a respiratory rate of 60 breaths per minute. His heart rate is also elevated, now at 180 beats per minute, with decreased peripheral pulses.
On auscultation, a harsh systolic murmur is heard over the left upper sternal border, along with crackles in the lung bases, suggesting fluid accumulation secondary to the worsening heart failure. The baby's skin is cool and mottled, and capillary refill time has increased to 4 seconds, indicating poor peripheral perfusion. Despite the high hematocrit, the baby's pallor and cyanosis have worsened, with central cyanosis now evident.
These findings suggest that the baby is entering a "tet spell" or hypercyanotic episode. This is a medical emergency, requiring immediate intervention to increase pulmonary blood flow and reduce right to left shunting. The medical team needs to reassess the current management plan, and consider the need for immediate palliative surgery to improve the baby's oxygenation and hemodynamic stability, before definitive surgical repair can be considered.
Section 4
New Diagnostic Results:
Despite the initial regimen of oxygen, morphine and beta-blockers, the infant's condition has not improved. An echocardiogram was performed which showed an overriding aorta, pulmonary stenosis, ventricular septal defect, and right ventricular hypertrophy - confirming the diagnosis of Tetralogy of Fallot. The pulmonary stenosis was found to be severe, causing a significant obstruction to the outflow of blood from the right ventricle to the lungs.
Laboratory results showed an elevated white blood cell count of 20,000/mm3, indicative of a possible infection. An arterial blood gas (ABG) analysis showed a PaO2 of 45 mmHg, confirming the hypoxemia. The PaCO2 was normal, indicating that the baby's respiratory system is compensating for the reduced oxygen by increasing his respiratory rate. However, the elevated heart rate and the presence of crackles on auscultation suggest that the compensatory mechanisms are nearing their limit. These results provide the medical team with valuable information to guide the management of the infant's condition.
The combination of the echocardiogram and laboratory results underscore the need for immediate intervention. The medical team must now decide between continuing aggressive medical management or proceeding with palliative surgery to alleviate the obstruction and improve the baby's oxygenation and overall clinical status.
Section 5
Change in Patient Status:
As the infant's condition continues to deteriorate, he is becoming increasingly lethargic. His skin color has become blue-tinged, particularly around the lips and fingertips, indicative of worsening hypoxemia. Despite the compensatory increase in respiratory rate, the PaO2 has dropped to 40 mmHg and the infant's heart rate has increased to 170 beats per minute.
New Complications:
A new complication has arisen in the form of fever, with a temperature of 38.5°C, further suggesting an infection. Another worrying sign is the sudden decrease in urine output to less than 1 mL/kg/hour, indicating potential renal impairment due to poor perfusion. With the combination of worsening hypoxemia, possible infection, and renal impairment, the medical team now faces a critical decision point. They must balance the urgency of surgical intervention against the risks associated with operating on a critically ill, potentially septic infant.