Further contributing to the bleeding risk is the presence of arteriolar dilation and increased tissue vascularity. This is felt to be secondary to increased release of endothelium-derived nitric oxide and prostaglandins in response to increased wall sheer stress in the setting of increased blood viscosity. Although patients with cyanosis have an increased risk for bleeding, this is not protective against thrombosis.
In the setting of cyanosis, these patients develop secondary erythrocystosis. Secondary erythrocytosis develops as a compensatory response to chronic hypoxia and results from overproduction of erythropoietin. This results in increased whole blood viscosity resulting from increased red blood cell mass and decreased plasma volume. The end result is decreased flow in the small arterioles and capillaries.
This is further exacerbated in the setting of iron deficiency and dehydration. Iron-deficient red blood cells are less deformable and have been found to be one of the strongest independent predictors of thrombosis in the setting of Eisenmenger syndrome. In the perioperative setting, preoperative fasting might exacerbate symptoms of hyperviscosity and increase the risk of cerebrovascular thrombosis. Thus, adequate hydration with intravenous fluids must be maintained, particularly in fasting patients. Careful preoperative assessment of the coagulation system is essential, and replacement of coagulation factors and platelets should be considered in patients undergoing moderate or major surgery.
In addition, iron deficiency should be corrected preoperatively if the procedure is not urgent. It is important to note, however, that in the setting of secondary erythrocytosis with increased hemogloblin and decreased plasma volume, standard techniques to measure International Normalized Ratio and activated partial thromboplastin time may be unreliable. Because of these changes, the concentration of citrate in the sampling tube must also be adjusted.
In most centers, the anticoagulant in the tube can be adjusted by the following formula: anticoagulant in sampling tube 3. Right-sided and left-sided heart failure are common complications of both corrected and uncorrected CHD. Increases in atrial natriuretic peptide, renin, aldosterone, and norepinephrine have been observed in adults with CHD many years after surgical correction, even in asymptomatic patients. Abnormal cardiac autonomic nervous system regulation and altered hemodynamics contribute to the development of heart failure in these patients.
Atrial and ventricular dysrhythmias are common in adults with CHD.
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Dysrhythmias arise in patients who have undergone previous curative or palliative surgery as a primary consequence of the underlying congenital defect or secondary to surgical repair. The most common form of tachyarrhythmia observed is intraatrial reentrant tachycardia originating from the right atrium. Atrial tachyarrhythmias are often resistant to pharmacological treatment and can result in rapid hemodynamic deterioration. Ventricular dysrhythmias are most frequently encountered in patients who have significantly decreased right or left ventricular function.
Other risk factors include previous ventriculotomy, earlier surgical era, or older age at initial surgery. Patients who were repaired late are exposed to longer periods of cyanosis, volume overload, and pressure overload. As a result, they have increased myocardial fibrosis and associated slowing of conduction and an increased risk for dysrhythmias. Acute hypoxemia can provoke ventricular dysrhythmias because subendocardial myocardial perfusion is already impaired in hypertrophied myocardium.
Some patients will require a permanent pacemaker to treat bradycardia secondary to postoperative atrioventricular block. The management of patients with pacemakers and intracardiac defibrillators has been reviewed elsewhere. The preoperative evaluation of patients with CHD undergoing noncardiac surgery should use a multidisciplinary approach that includes the participation of anesthesiologists, cardiologists, intensivists, and surgeons. Guidelines of the task force for the organization of delivery systems for adults with CHD recommend that patients with moderate or complex CHD should be managed in a regional adult congenital heart disease center.
Therefore, the anesthesiologist should be familiar with the patient's specific anatomy and physiology as determined from echocardiographic and cardiac catheterization results. This knowledge is useful to anticipate intraoperative events that may precipitate acute changes in the magnitude or direction of intracardiac shunts or modulate flow through systemic to pulmonary shunts. If recent examination results are not available, a preoperative echocardiogram may be indicated. Many adults with CHD undergoing noncardiac surgery have undergone previous cardiac surgery and are familiar with anesthesia.
Some may present with anxiety, physical limitations, and associated anomalies or syndromes the most common is trisomy Adults with CHD are more likely to be living with their parents and to develop a variety of psychosocial issues. Premedication with anxiolytics and hypnotics must be undertaken very cautiously because hypoventilation and hypercapnia may produce deleterious increases in pulmonary vascular resistance, particularly, in patients with underlying pulmonary hypertension or systemic to pulmonary shunts.
However, patients with chronic hypoxemia retain a normal ventilatory response to hypercarbia as well as to opioid analgesics.
The American Heart Association has recently published updated guidelines for the prevention of infective endocarditis. As result, only patients with cardiac conditions associated with the highest risk for adverse outcomes should continue following antibiotic prophylaxis before surgery: patients with previous endocarditis, unrepaired cyanotic CHD, including palliative shunts and conduits; completely repaired congenital heart defects with prosthetic material or device, whether placed by surgery or by catheter intervention, during the first 6 months after the procedure; repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device which inhibit endothelialization.
Except for the conditions listed above, antibiotic prophylaxis is no longer recommended for other forms of CHD. Adults with CHD who have undergone complete anatomic repair and have no evidence of late functional deterioration can be managed by using conventional approaches. In contrast, patients with more complex CHD and moderate to major surgery will require specific intraoperative management. In addition to direct examination of the patient, standard conventional noninvasive monitoring including pulse oximetry, electrocardiogram, arterial blood pressure, capnography and temperature are used in all patients.
Pulse oximetry is perhaps uniquely important in the management of CHD. For example, decreases in arterial saturation can signify increases in pulmonary vascular resistance, increases in right to left shunting, or decreases in pulmonary blood flow through systemic to pulmonary shunts. In contrast, increases in left to right shunting may not be detected by pulse oximetry and arterial oxygen saturation may be maintained even if systemic cardiac output is severely compromised.
The capnogram is altered, and end tidal carbon dioxide concentrations underestimate Paco 2 in the case of right to left shunting.
MEF2C loss-of-function mutation contributes to congenital heart defects
Knowledge of the anatomy and physiology of specific palliative repairs is important for choosing appropriate monitoring. For example, congenital defects that are associated with inadequate pulmonary blood flow e.
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In patients with a classic Blalock-Taussig shunt end to side anastomosis of the subclavian and pulmonary arteries arterial pressure and Spo 2 cannot be measured on the ipsilateral side. A Glenn shunt or bidirectional cavopulmonary anastomosis consists of an end to side anastomosis of the divided superior vena cava to pulmonary artery. Total cavopulmonary connection Fontan circulation is established when the pulmonary and systemic circulations are totally separated by diverting all the systemic venous return to the pulmonary artery, usually without interposition of a subpulmonic ventricle.
These alterations in intracardiac anatomy complicate the placement of central venous catheters in palliated adults, and the anatomical variations must be considered when interpreting values obtained from central venous monitoring. For example, in patients with a Fontan circulation, central venous pressure reflects mean pulmonary artery pressure.
In patients with an intraatrial baffle e. Vascular access may also be difficult because many of these patients have already undergone previous vessel catheterization.
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Invasive arterial pressure monitoring can be essential in managing patients with Eisenmenger syndrome, intracardiac or systemic to pulmonary shunts undergoing major surgery who are also sensitive to sudden changes in preload, and systemic and pulmonary vascular resistance. Finally, transesophageal echocardiography might be useful in adults with CHD undergoing noncardiac surgery to monitor intravascular volume status and ventricular function. In the presence of complex CHD, transesophageal echocardiography should be performed by an individual familiar with CHD.
There are no evidence-based recommendations to guide the anesthetic management of patients with CHD undergoing noncardiac surgery. Advanced Cardiovascular Surgery. New York; Crane and Stratlon Total Cavopulmonary anastomosis versus conventional modified Fontan procedure. Ann Thorac Surg ; Modified Fontan operation for univentricular heart and complicated congenital lesions. J Thorac Cardiovasc Surg.
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A palliative approach to complete transposition of great arteries. JAMA ; — Kaye MP. Anatomic correction of transposition of great arteries. Mayo Clin Proc ; — Rapid two stage arterial switch for transposition of great arteries and intact interventricular septum beyond neonatal period. Circulation ; 80 Suppl 1 : — Long term results after atrial repair of transposition of great arteries in early infancy. Transposition of great arteries and intact ventricular septum, anatomical repair in the neonate.
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Natural history of common congenital heart diseases
Cite article How to cite? If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Congenital heart defects can present at different ages with clinical signs and symptoms ranging from cyanosis to cardiovascular collapse or congestive heart failure CHF depending on the anatomy and physiology of the lesion.
Long-term survivors are at risk for a number of postoperative complications. This chapter examines congenital heart defects and begins with a review of fetal and neonatal cardiac physiology, followed by a discussion of specific lesions and their diagnosis and management organized by clinical presentation. A brief discussion of pediatric murmurs follows, and this chapter concludes with a discussion of common surgical procedures for repairing congenital heart defects and associated complications.
Congenital heart defects occur in approximately 8 in births and range from benign to life-threatening. Congenital heart disease is usually classified based on physiology presence or absence of cyanosis, with or without persistent fetal circulation or on the nature of the anatomic defect shunt, obstruction, transposition, or complex defect. Most textbooks separate cyanotic from acyanotic lesions. Acyanotic lesions include those that result in pulmonary overcirculation such as ventricular septal defect VSD , atrial septal defect ASD , patent ductus arteriosus PDA , and atrioventricular AV canal, as well as those with restricted pulmonary or systemic blood flow such as pulmonary stenosis, aortic stenosis, and aortic coarctation.
It is often more useful to organize congenital heart disease by clinical presentation Table A Distinct clinical presentations are discussed further in later sections, including the pathophysiology, clinical features and treatment, and individual defects within each group. Discussion of murmurs and arrhythmias included in this chapter is limited to those related to congenital heart disease. This div only appears when the trigger link is hovered over.
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