Advanced Pathophysiology: Hypoplastic Left Heart Syndrome (HLHS)
Client’s Presenting Complaints, Symptoms, and History
Hypoplastic left heart syndrome is a malformation on the left side of the heart. In this situation, several symptoms appear in a child, including poor feeding habits, rapid and difficult breathing, cyanosis, namely, skin color turning to grayish-blue, as well as having cold limbs. Besides, the child also may suffer from congenital immune deficiency syndrome, where the body fails to adequately protect itself from diseases and infections.
HLHS occurs in 7 to 9% of neonates who are diagnosed with a heart disease condition during the first year of birth. According to National Birth Defects Prevention Network, in every 4,344 live birth in America, one of them suffers from HLHS (Feinstein et al., 2012; Ming-Sing, 2014). That could mean about 960 children per annum. The disease accounts for about 25% of deaths happening in the first week of life (Feinstein et al., 2012; Ming-Sing, 2014).
Inadequate development of the left ventricle at the time of birth leads to the occurrence of HLHS, which could happen under varying degrees of mitral valve, aorta artresia, or hypoplasia. For systematic perfusion, children born with HLHS rely on patent ductus arteriosus. The patients demonstrate a sole cardiovascular physiology that requires systematic as well as pulmonary vascular resistance to come under manipulation. Such a procedure helps to attain a balanced circulation containing sufficient systematic oxygen delivery. As the capillary beds of both the pulmonary and systematic vascular are supplied from a single vessel, their corresponding resistance determines the relative blood flow allocation to the systematic and pulmonary circulations. After birth, pulmonary vascular resistance (PVR) goes into a gradual decrease for some days.
This situation causes an increase in the pulmonary blood flow, and consequently, rises the right ventricle’s volume load. Although the infant may experience rising systematic oxygen saturation, there is a sufficient risk of continuous congestive heart failure. Again, the possibility of decreased systemic perfusion becomes visible due to the small size and inadequate functioning of left-sided cardiac structures. Numerous left-sided obstructions lead to the reduced aortic blood flow as well as consequent reduction in coronary artery flow. The stream is dependent on retrograde flow at the time of diastole from the patent ductus arteriosus heading into the undersized ascending aorta.
Functional unit of disease process. The left ventricle chamber of the heart receives oxygen-saturated blood from the left atrium and pumps it through the aorta to the rest of the body. In case of HLHS, this function is threatened because of the fact that the oxygen-saturated blood mixes with unsaturated one. Further, the entirely blood saturated pulmonary venous headed to the left atrium do not gain access to the left ventricle as a result of hypoplasia, mitral valve stenosis, or atresia. These circumstances force the blood from venous to cross atrial septum. In many cases, patent foramen ovale becomes available whereby it appears small and partly obstructive. The above condition causes the mixture of the saturated and de-saturated blood. Right ventricle ought to pump the mixed blood to both systematic and pulmonary circulations.
The connection between them is parallel as opposed to series, with the ductus arteriosus. Exit from the right ventricle could be headed to lungs through pulmonary arteries branch, or to other parts of the body through ductus arteriosus. The blood amount flowing into every circulation depends on each circuit’s resistance. Therefore, at birth, the pulmonary artery takes the blood to the lungs as opposed to the body.
Homeostasis, stress, compensation, and adaptation. In patients with HLHS, the right ventricle is under some systematic pressure as well as blood loading volume. Examination of HLHS specimen identifies condensed cardiac extra-cellular, which could contribute to myocyte spillage and suboptimal ventricular function. Myocyte homeostasis changes are characterized by the increase in apoptosis and continuous net loss of the myocyte. This situation leads to ventricular dysfunction. The right ventricle is stressed as it pumps blood to the entire body, which is a function of the left ventricle. The right ventricle has to adapt after hemi-Fontan medication whereby, there is volume reduction from the perspective of ejection fraction, as well as preserved stroke quantity.
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Genetic components. Sometimes, families with history of cardiac defects have increased chances of having offspring suffering from HLHS. The deficiency also is associated with abnormal facies, cardiac defects, cleft palate, thymic hypoplasia and hypocalcemia. The defects are propagated through a chromosomal deletion in the 22q11 (McHugh, Hillman, Gurka, & Gutgesell, 2010). Furthermore, children having the genotype MTHFR 677TT are at higher risks of contracting cardiac defects. The gene regulates homocystine, and its presence together with low levels of folate develops a possibility of cardiac defects.
In the diagnosis of HLHS, doctors averagely apply echocardiogram. The procedure makes use of high-pitched sound waves. The produced waves bounce off the infant’s heart constructing moving images that are displayed on an electronic monitor. In HLHS, the generated echocardiogram will show an aorta and a left ventricle that appear to be smaller than normal. Again, since the test can track blood flow, it is possible to notice the blood movement to the aorta from the right ventricle.
Medical and Surgical Treatment
Treating children suffering from HLHS will require several surgeries to be performed in their lifetime. The first operation ought to take place within first weeks of life. However, before the performance of the surgery prostaglandin, a drug used to maintain an open ductus arteriosus could be prescribed. This option allows blood to flow to other parts of the body. At that point, it could be necessary to determine whether the infant requires a breathing machine. The surgery occurs in three stages, including Norwood procedure, Glenn operation and Fontan procedure.
HLHS infant patients go through some difficult life experiences, and their parents are stressed on making the right decisions. This circumstance necessitates the need for nursing care for both the clients and their families. Nurses should be in a position to recognize as well as use ethical values related to both care delivery and informed consent.
Collaborative treatment. Nursing job requires the practitioners to collaborate with all relevant stakeholders. Namely, nurses should assist a physician treating the patient, the patient and one’s family. Nurses ought to collaborate with parents in the determination of crucial strategies for restoring a level of normalcy, hence promoting the child’s independence and well-being.
Health promotion and prevention. The disease does not have any known prevention mechanism. However, parents with a history of cardiac defects could seek advice from genetic counselors.
Psycho-Socio-Cultural Considerations. HLHS patients, similarly to other patients with heart defects, could experience co-morbid health malfunctions due to the disease. They could suffer organ failure in the long-run or even death.
In the article “Surgical Treatment of Pediatric Hypoplastic Left Heart Syndrome,” the authors overview the surgical process of the medication of the defects. Although the editorial evidently insists on the non-existence of HLHS cure, it argues that several staged reconstructions could contribute to improvement of health. The staged reconstructions include Norwood procedure, Blalock-Taussig shunt (MBTS), and Fontan which should be performed in phase one, two and three respectively (Ming-Sing, 2014). The article also advocates for a cardiac transplant, though with reservations due to the scarcity of neonatal organs donor.
Another study, “Hypoplastic Left Heart Syndrome: Current Considerations and Expectations,” focuses on changes in HLHS management, a diagnostic approach, as well as the outcomes of these procedures. According to the commentary, despite that the survival rate for patients aged five years was between 50% and 69%, today’s expectations of such children reaching adulthood stands at 70% (Feinstein et al., 2012). The indicators could be due to the improved stage three treatments. The article covers pre-stage one, neo-fetal and fetal management and assessment.
One more article is the “Nutrition Algorithms for Infants with Hypoplastic Left Heart Syndrome; Birth through the first Inter-stage Period.” The editorial considers the shortcomings of surgery stages and importance of nutrition for HLHS patients (Slicker et al., 2012). The research concludes that a proper feeding protocol shows maximum benefits while reducing EN risks during management of acutely ill patients, such as those of HLHS.
Clinical Practice Guidelines (CPG)
Current evidence-based CPG. With the left-side of the heart experiencing obstructions, regular blood flow becomes dependent on right-to-left stream via patent ductus arteriosus. This circumstance makes the infants duct-dependent. The clinical procedure administered involves a double lumen umbilical venous catheter insert. At a starting dose of 10ng/kg/minute, prostaglandin infusion is commenced. At this point, over-oxygenation of the child should be avoided. Next, oxygen saturation of above 75% is accepted. However, it should be reduced if the saturations go above 85%. After that, the nurse has to contact a pediatric cardiologist between midnight and 6.30 in the morning in case saturations stand below 75%, if not, one can be reached at 6.30 a.m. At the same time, the infant ought to continue at nil by mouth. In the case of assisted breathing, the practitioner should prevent over-ventilation. The objective is to maintain low to normal arterial pH.
Guideline critique. The guidelines appear to be the anticipated primary outcomes, and hence, may not be as accurate as could be expected.
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