Prevalence

ASDs ( Fig. 1 ) comprise 6% to 10% of all CHD, affect women and girls more than men and boys. More than 75% of all ASDs are ostium secundum types, arising from enlargement of the foramen ovale, reabsorption of the septum primum, or inadequate growth of the septum resulting in a secundum type.

ASD. A communication between the left and right atria is shown. Ao, aorta; IVC, inferior vena cava; LA, left atrium; LV, left ventricle; MPA, main pulmonary artery; MV, mitral valve; RA, right atrium; RV, right ventricle; SVC, superior vena cava; TV, tricuspid valve.

( Courtesy of the Centers for Disease Control and Prevention, Bethesda, MD; https://www.cdc.gov/ncbddd/heartdefects/AtrialSeptalDefect-graphic2.html .)

Overview and Anesthetic Implications

Left-to-right shunts in patients with ASD cause increased right heart (RH) circulation and possible RH dilation leading in some to arrhythmias (atrial fibrillation in up to 23% of adults) and placing the patient at risk of atrially originating embolism. Volume overload of the RH can eventually cause right ventricular dilation. Increased pulmonary blood flow may eventually lead to pulmonary congestion and pulmonary hypertension. Noxious stimuli, hypothermia, acidosis, hypoxia, and hypercarbia associated with surgery can worsen pulmonary hypertension and right-to-left shunting.

Although most solo ASDs will have a predominantly left-to-right shunt, it is possible for patients to have right-to-left shunt when pulmonary vascular resistance (PVR) increases above systemic vascular resistance (SVR), causing a risk of paradoxic embolus. It is therefore vital to remove all air bubbles from intravenous lines in order to prevent stroke. The effects of anesthesia on SVR increase the likelihood of a right-to-left (hypoxic) shunt.

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  Concerns:

  
  
  
  
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    Right heart over circulation

    
    
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    Arrhythmias

    
    
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    Pulmonary hypertension

    
    
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    Hypoxic shunt

    
    
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    Paradoxic embolus

  
  

Prevalence

VSDs are the most common lesion, found in approximately 30% of patients with CHD. ^, VSDs ( Fig. 2 ) are often diagnosed after discovery of a pansystolic murmur. Small VSDs are rarely clinically significant. Upwards of 40% resolve spontaneously during childhood, specifically muscular VSDs. ^, Larger VSDs, which produce significant shunting, may require repair as early as infancy or may not be discovered until they become clinically significant later in life.

VSD. Examples of conoventricular, perimembranous, inlet, and muscular ventricular defects creating a communication between the left and right ventricles are shown. AoV, aortic valve; PV, pulmonary valve.

( Courtesy of the Centers for Disease Control and Prevention, Bethesda, MD; https://www.cdc.gov/ncbddd/heartdefects/images/vsd_simple-lg.jpg .)

Overview and Anesthetic Implications

Patients with VSD often have a volume-overloaded left heart, leading to left atrial and ventricular dilation. Up to 5% of patients with VSDs has a conduction defect, sometimes requiring a pacemaker. Many VSDs that require closure are now occluded with devices in the catheterization laboratory. However, larger or more complex VSDs require surgical intervention. Most adult patients with clinically significant VSDs will have had either device closure or surgical repair before adulthood. Because of significant shunting with larger VSDs, patients who have been repaired may already have developed pulmonary overcirculation resulting in a residual pulmonary hypertension and right ventricular hypertrophy, or Eisenmenger syndrome. This state of higher right-sided cardiac pressures puts the patient at risk for paradoxic embolus. Patients who remain unrepaired may present with biventricular hypertrophy as compensation for dramatic over circulation.

Along with SVR decreases owing to anesthesia, noxious stimuli, hypoxia, and hypercarbia may lead patients with pulmonary hypertension to have a decrease in Qp:Qs and therefore subsequent oxygen desaturation secondary to right-to-left shunting. Conversely, in patients with large, unrestricted VSDs who have an increased SVR, hyperoxia and hypocarbia may result in pulmonary overcirculation under anesthesia and subsequent hypotension and pulmonary edema. However, most adults with unrepaired VSDs do not have lesions large enough to cause significant hemodynamic instability. It should be noted that all patients with unrepaired VSDs are at risk for endocarditis before repair.

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  Concerns:

  
  
  
  
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    Left heart overcirculation and dilation

    
    
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    Right heart overcirculation

    
    
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    Arrhythmias

    
    
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    Eisenmenger syndrome

    
    
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    Pulmonary hypertension

    
    
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    Hypoxic shunt

    
    
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    Paradoxic embolus

    
    
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    Endocarditis

  
  

Prevalence

Of all valvular CHD lesions, bicuspid aortic valve is by far the most common, encompassing almost 2% of the general population and accounting for more than half of patients requiring aortic valve replacement before age 70.

Overview and Anesthetic Implications

The 2 main subcategories of congenital valvular heart disease are obstructive and stenotic, although both may be present. For example, patients born with bicuspid aortic valve will often develop both aortic valve stenosis and regurgitation in adulthood. Often there is no need for operation in childhood, but eventually many valvular diseases require surgical intervention.

Obstructive lesions, such as aortic stenosis or pulmonary atresia ( Fig. 3 ), place the patient at increased risk of perioperative morbidity and mortality. Severity of the lesion and symptoms including but not limited to congestive heart failure determine the timing of need for surgical repair. As the obstructive lesion worsens, the ventricle hypertrophies, leading to increased dependence on atrial contraction for contribution to left ventricular end diastolic volume. Therefore, sinus rhythm and preload are both vital to maintaining cardiac output, and adequate SVR is required for coronary perfusion to avoid myocardial ischemia. ^, Regurgitant valve lesions require that the patient be maintained in a normal to high heart rate in order to maintain cardiac output and forward flow, and bradycardia should be avoided. In addition, a normal or mildly reduced SVR is needed for adequate end-organ perfusion, and providers should prevent hypertension.

Pulmonary atresia with intact ventricular septum. An atretic pulmonary valve with intact ventricular septum leading to a small right ventricle is shown. PDA, patent ductus arteriosis; PFO, patent foramen pvale; VS, ventricular septum.

( Courtesy of the Centers for Disease Control and Prevention, Bethesda, MD; https://www.cdc.gov/ncbddd/heartdefects/images/PulmonaryAtresia-intact-600px.jpg .)

Although both types of valvular lesions present unique anesthetic implications, often the patients have already had surgical repair and will therefore have another additional set of perioperative risks for the consideration by the anesthesia provider. For patients who have undergone valve repair, risks for noncardiac surgery include inadequate repair with a residual lesion, leaflet perforation, perivalvular pseudoaneurysm, annular dilation leading to regurgitation, hematoma, and endocarditis. Patients who have valve replacement in lieu of repair will have an entirely different set of implications for the perioperative period. Regardless of autograft, homograft, or mechanical valve replacement, complications include valve dysfunction and endocarditis. Furthermore, mechanical valves have additional risks, such as thromboembolism and need for anticoagulation, leading to bleeding. Other rarer cardiac valve lesions include Ebstein anomaly, which is characterized by a downwardly displaced, often dysplastic tricuspid valve, and atrialization of a portion of the right ventricle. These lesions often need surgical repair as well as lifelong follow-up with cardiology owing to risk of arrhythmias, including Wolff-Parkinson-White syndrome and sudden cardiac death in adulthood.

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  Concerns:

  
  
  
  
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    Obstructive lesions:

    
    
    
    
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      Maintenance of sinus rhythm

      
      
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      Ventricular hypertrophy

      
      
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      Maintenance of SVR for coronary perfusion

    
    
    
    
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    Regurgitant lesions:

    
    
    
    
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      Maintenance of normal/fast heart rate

      
      
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      Reduction of SVR to maintain normal flow

    
    
    
    
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    After valve surgery

    
    
    
    
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      Inadequate repair

      
      
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      Postrepair complications: hematoma, aneurysm

      
      
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      Endocarditis

    
    
    
    
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    After valve replacement

    
    
    
    
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      Thromboembolism

      
      
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      Bleeding secondary to anticoagulation

      
      
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      Endocarditis

    
    

  
  

Prevalence

Coarctation of the aorta ( Fig. 4 ) is a common defect seen in 6% to 8% of patients with CHD and in 0.06% to 0.08% of the general population; it is more common in men and boys than in women and girls. It may be isolated but often occurs with other cardiac and vascular lesions, including VSD, bicuspid aortic valve, mitral valve stenosis, and circle of Willis aneurysms. ^, The most common genetic cause of coarctation of the aorta is Turner syndrome, characterized by XO sex chromosomes and often associated with left-sided heart defects. First-degree relatives of patients with coarctation of the aorta have a 10-fold increase in risk of having an obstructive left-sided lesion.

Coarctation of the aorta. A coarct, or abrupt narrowing, of the aorta is shown.

( Courtesy of the Centers for Disease Control and Prevention, Bethesda, MD; https://www.cdc.gov/ncbddd/heartdefects/images/coarctationlayoutv2-575px.jpg .)

Overview and Anesthetic Implications

Aortic coarctation is characterized by a discrete narrowing of the aorta, usually adjacent to the location of the ductus arteriosus. Symptoms include precoarctation hypertension found in the upper extremities, hypotension in the lower extremities, and left ventricular hypertrophy on electrocardiogram. Long-term survival without repair is significantly reduced, because without surgical intervention, mortality is 75% by age 50. Untreated coarctation of the aorta can be associated with premature coronary artery disease, left ventricular dysfunction, aortic aneurysm/dissection, and cerebral vascular disease, despite development of significant collateral blood flow.

Although there is increased morbidity and mortality without intervention, surgical repair has its own set of associated complications, including most commonly restenosis, which is seen in up to 10% of patients. Other issues include aortic root aneurysm, aortic dissection, collateral vessel aneurysm, and less commonly, lower-extremity paralysis or other perfusion-related spinal cord injuries from aortic cross-clamp time during the procedure. Furthermore, age of the patient at time of repair also has implications for long-term outcomes and associated issues. Thus, 90% of patients repaired in childhood has no hypertension, but 50% of those repaired after age 40 has persistent hypertension.

Several considerations are needed when caring for patients with coarctation of the aorta during noncardiac surgery, starting with if the patient has had surgical repair. Issues such as hypertension, left ventricular hypertrophy, aortic root aneurysm, spinal cord hypoperfusion injuries, and other associated issues can influence the surgical plan and must be thoroughly investigated before noncardiac surgery. ^, The timing of the operation or intervention also heavily influences the types of likely sequelae, with later–in-life operations having more long-term issues, including coronary artery disease and long-standing hypertension. The type of repair also affects the possible long-term effects, with end-to-end anastomotic repair more frequently (3%) causing restenosis, but patch repair more commonly causing aortic root aneurysm. ^, Regardless of treatment, patients born with coarctation of the aorta have a lifelong increase in the risk of cerebral artery aneurysm. Therefore, all patients with coarctation should be followed long term by a congenital cardiologist.

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  Concerns:

  
  
  
  
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    Associated cardiac defects and genetic syndromes

    
    
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    Management of hypertension

    
    
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    Coronary artery disease

    
    
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    Cerebral vascular disease

    
    
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    Restenosis

    
    
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    Aortic root aneurysm

    
    
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    Aortic root dissection

    
    
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    Collateral blood vessels

    
    
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    Paraplegia

    
    
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    Spinal cord hypoperfusion injuries from repair

    
    
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    Age of patient at time of repair

  
  

Prevalence

The 10- and 20-year survival of patients receiving a Fontan shunt is greater than 90% and 84%, respectively. Because palliative surgery can be between 18 months and 2 years of age, but on average childhood to early teen years, patients will present as adults with palliated single-ventricle (Fontan) physiology for noncardiac surgery. The number of adults with univentricular physiology is increasing.

Overview and Anesthetic Implications

Congenital cardiac lesions that are not amenable to biventricular repair are palliated with Fontan physiology, resulting in total cavopulmonary connection (TCPC). In TCPC, the superior vena cava and inferior vena cava are directly connected to the pulmonary arteries (Glenn and Fontan anastomoses, respectively), which takes the circulation of patients with single-ventricle physiology from parallel to series. Several lesions may require Fontan palliation, including hypoplastic left heart syndrome (HLHS) ( Fig. 5 ), tricuspid atresia ( Fig. 6 ), double-outlet right ventricle, right ventricle hypoplasia, severe Ebstein anomaly, double-inlet right ventricle, and unbalanced atrioventricular canal (AVC). Regardless of the original lesion, the resulting physiology causes total dependence of cardiac output on passive pulmonary blood return. The 1 exception seen to this complete dependence occurs in patients with a fenestrated Fontan conduit. The fenestration allows augmentation of cardiac output by directly supplying additional volume to an underfilled ventricle.

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