The Journey

The Neonatal Heart

The neonatal heart is very different from the fully mature adult heart. First the neonatal heart has decreased myocardial contractile force, and the heart contains 50% reduction in myofibers and a greater quantity of non connective tissue. These myofibers are also aligned in a non linear pattern. Overall the neonatal heart is dependent of an accelerated heart rate and catecholamines rather than preload.

 

Cardiopulmonary Bypass (CPB)

The CPB is essential to congenital heart disease and pediatric cardiothoracic surgery. This was a huge advancement in postoperative care and in the betterment of recovery for patients. Management of CPB for congenital heart disease differs from that for adults because of the problems of aortopulmonary shunts, the immature cardiovascular system, and the eventual use of deep hypothermic circulatory arrest. During deep hypothermic circulatory arrest, the blood available in the systemic veins (generally the cavas vein) is drained to the oxygenator, which provides oxygen, removes carbon dioxide, and reduces the blood temperature. In the process, the oxygenated blood returns to the aorta by a system of pumps that generates continuous flow from the CPB to the patient. In general, CPB alters all physiological processes of the organism and may lead to organic dysfunction of different magnitudes. The morbidity associated with CPB is largely associated with damage to blood elements and proteins caused by blood gas alterations and the prosthetic surface interface.

 

Postoperative Care

Adequate monitoring during the postoperative period involves a combination of clinical or auxiliary methods for evaluating the surgical correction, myocardial function, and the relationship between systemic and pulmonary blood flow. Standard monitoring in the postoperative period is similar to that during anesthesia and surgery. Sometimes, depending on the clinical evolution, more sophisticated monitoring may be added to facilitate clinical diagnosis and treatment. Standard monitoring consists of ECG, direct arterial pressure,temperature probe, and central venous pressure. In the first stage of recovery the patient needs intense monitoring. In postoperative care of the pediatric patient, clinical evaluation must be complete and systematic. Consequently, complications can be foreseen, and catastrophic situations can be avoided. Care should be initiated while the child is still in the operating room, with special attention to rewarming to 36.5ºC, control of bleeding, ventilation, and acid-base and electrolyte balance. It is very important during this phase to stabilize cardiac function through maintaining correct intravascular volumes, adequate heart rate, and adequacy of myocardial contractility. Another important factor in postoperative care is a strong and effective ICU team and cardiac team.

 

Clinical Examination

Important clinical signals for the evaluation of cardiac output are perspiration, adequate level of consciousness, coloring and temperature of extremities, thermal gradient between knees and feet, central and peripheral thermal gradient, amplitude of peripheral pulse, capillary filling, arterial pressure, and urinary output. Accordingly, cardiac output is considered adequate when there is no cold perspiration or psychomotor agitation, the members of extremities are warm and colored, the feet are hotter than the knees, the central-peripheral thermal gradient is less than 4oC, the peripheral pulse is easily palpable, capillary filling is satisfactory, arterial pressure is within the normal limits for the age group, and urinary output is greater than l mL/kg/hour. It is important to remember that adequate peripheral vasodilatation only occurs after the fourth postoperative hour, with normal re-establishment of tissue perfusion around the sixth postoperative hour. Examining a patient can prevent and treat complications after surgery.

 

Low cardiac output

Low postoperative cardiac output is primarily caused by reduction in myocardial contractility caused by one of the mechanisms or factors above mentioned. The LCOS is a well-recognized, frequent post-operative complication with an accepted collection of hemodynamic and physiologic aberrations. Approximately 25% of children experience a decrease in cardiac index of less than 2 L/min/m2 within 6-18 hours after cardiac surgery. Post-operative strategies that may be used to manage patients as risk for or in a state of low cardiac output include the use of hemodynamic monitoring, enabling a timely and accurate assessment of cardiovascular function and tissue oxygenation; optimization of ventricular loading conditions; the judicious use of inotropic agents; an appreciation of and the utilization of positive pressure ventilation for circulatory support; and, in some circumstances, mechanical circulatory support. All interventions and strategies should culminate in improving the relationship between oxygen supply and demand, ensuring adequate tissue oxygenation.

 

Postoperative Fever

A fear in pediatric cardiac surgery for both the surgeon and the patient is postoperative fever, a common postoperative problem in pediatric cardiac surgery. Fever after surgery is most of the time benign and self limiting; however, fever that develops after the first 48 hours can be dangerous. Postoperative fever is generally related to the use of cardiopulmonary bypass(CPB), hypothermia, and post- perfusion syndrome. Noninfectious causes include, blood contact with the CPB circuit, presence of endotoxemia, and the development of ischemia reperfusion injury secondary to aortic cross- clamping. Trauma and the incidence of postpericardiotomy is also a noninfectious cause of postoperative fever. The next type of cause discussed by the article were nosocomial infections, common nosocomial infections are bloodstream infections, lower respiratory tract infections, and surgical site infections. The approach to postoperative fever is discussed next. A fever within the first 24 hours after surgery is an inflammatory response to CPB, which means it will usually resolve by itself. The presence of fever 48 hours after surgery is when an evaluation of the cause of the fever is appropriate, because it indicated a deep- seated infection that is dangerous to the patient. This evaluation includes a careful history, targeted physical examination, and additional tests and studies. History is also important to note when searching for the cause of a deep-seated infection. Young infants with a fever are more likely to have an infection. According to the article “Patients with poor nutrition or/and immunosuppressed are more likely to develop nosocomial infections”. Drug hypersensitivity is important to look at when searching for a cause of a fever as well. Preoperative care is also important to note since patients with a previous infection can carry several risks related to a postoperative infection. Continuous and careful examinations are important in postoperative care to ensure a fever’s cause and if an infection is present. Several tests should also be conducted.

Work Cited

Otavio Costa Auter, Joao et al. “PEDIATRIC CARDIAC POSTOPERATIVE CARE.” Revista    Do Hospital Das Clínicas, vol. 57, no. 3, 18 May 2001, doi:http://dx.doi.org/10.1590/S0041-87812002000300007 .

 

Gupta, Ajayk et al. “Approach to Postoperative Fever in Pediatric Cardiac Patients.” Annals of Pediatric Cardiology, vol. 5, no. 1, 2012, pp. 61–68. doi:10.4103/0974-2069.93714.

 

"Management of the Low Cardiac Output Syndrome Following Surgery for Congenital Heart Disease." Current Cardiology Reviews. U.S. National Library of Medicine, n.d. Web. 23 Jan. 2017.

​

​