Pediatric Anesthesia ISSN 1155-5645
REVIEW ARTICLE
Anesthesia and the pediatric cardiac catheterization suite: a review Jennifer E. Lam, Erica P. Lin, Ryan Alexy & Lori A. Aronson Department of Anesthesia/Cardiac Anesthesia, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
Keywords congenital heart disease; cardiac catheterization; anesthesia; children; sedation; complications Correspondence Dr. Jennifer E. Lam, Department of Anesthesia, Cardiac Anesthesia, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 2001, Cincinnati, OH 45229-3026, USA Email: [email protected] Section Editor: C. Dean Kurth Accepted 4 September 2014 doi:10.1111/pan.12551
Summary Advances in technology over the last couple of decades have caused a shift in pediatric cardiac catheterization from a primary focus on diagnostics to innovative therapeutic interventions. These improvements allow patients a wider range of nonsurgical options for treatment of congenital heart disease. However, these therapeutic modalities can entail higher risk in an already complex patient population, compounded by the added challenges inherent to the environment of the cardiac catheterization suite. Anesthesiologists caring for children with congenital heart disease must understand not only the pathophysiology of the disease but also the effects the anesthetics and interventions have on the patient in order to provide a safe perioperative course. It is the aim of this article to review the latest catheterization modalities offered to patients with congenital heart disease, describe the unique challenges presented in the cardiac catheterization suite, list the most common complications encountered during catheterization and finally, to review the literature regarding different anesthetic drugs used in the catheterization lab.
Introduction Innovations have shifted the scope of pediatric cardiac catheterization from a diagnostic tool towards therapeutic intervention (1,2). Advances in cardiac imaging and novel devices offer patients a wider range of nonsurgical options, possibly postponing or replacing surgical intervention. However, data from the Pediatric Perioperative Cardiac Arrest registry show that nearly one-third of cardiac arrests occur in children with congenital heart disease (CHD), of which 17% occur during cardiac catheterization (3). Thus, the anesthesiologist practicing in the catheterization suite must be familiar with CHD and the unique limitations that are specific to this environment. The cath lab The cardiac catheterization suite is a challenging environment. The physical isolation from additional anesthesia resources combined with limited functional space that hinders access to the patient can make emergency resuscitation more difficult (4). Medications and airway © 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
devices should be within easy reach. Expandable breathing circuits and intravenous tube extensions are often needed. Cardiac catheterization, especially cine fluoroscopy, delivers some of the highest doses of radiation with no known safe dose to mitigate cancer risk (5–8). Dosimeters should be worn to monitor cumulative radiation exposure. Personnel should adhere to three radiation safety principles to reduce occupational exposure: (i) maintain maximal distance from the source, (ii) minimize exposure time, and (iii) use proper shielding (e.g. wrap-around lead apron, thyroid collar, protective eyewear) (4). Mobile lead screens add further protection. Goals of catheterization Diagnostic catheterizations provide additional understanding of a patient’s anatomy, hemodynamics, myocardial function and/or responsiveness to medications and respiratory interventions. Hemodynamic data is often acquired in room air when dissolved oxygen is negligible and therefore not included in subsequent calculations of flow and resistance. If supplemental oxygen 127
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Anesthesia and pediatric cardiac cath
is administered, calculations must account for dissolved oxygen. Thus, communication between the anesthesiologist and cardiologist is crucial. Pulmonary flow (QP) and systemic flow (QS) can be calculated using the Fick principle, which states that flow is equal to the patient’s oxygen consumption divided by the difference in oxygen content across the vascular bed in question (Table 1). In patients without shunting, QP equals QS. Shunt defects, however, alter the QP:QS ratio. Pulmonary and systemic vascular resistances (PVR, SVR) are similarly calculated using Poiseuille’s equation, which relates resistance to vascular pressure divided by volumetric flow rate (Table 1). It should be noted, however, that this calculation is based on laminar vs turbulent flow and assumes a normal blood viscosity. Traditionally, oxygen consumption (VO2) is calculated based on heart rate, gender and age (from 3 to 40 years) using the LaFarge equation, but is less accurate in children 10 kg in conjunction with transesophageal echocardiography. More recent advancements in the field include transcatheter valve replacement. In CHD, these valves are most commonly placed in failing pulmonary bioprosthetic valves or right ventricle to pulmonary artery conduits. Large femoral sheaths are often needed for device deployment, and the resulting vascular access site may be closed by a percutaneous suture delivery device. Complications Causes for cardiac catheterization adverse events can be classified into eight main categories (Table 2) that can be further subdivided into minor and major events. Generally, minor events include those that are transient and resolve with or without treatment. The spectrum of major events includes death, cardiac arrest, hypotension
Table 1 Hemodynamic calculations using cardiac catheterization data Hemodynamic variable
Equation
Normal values
Oxygen consumption
VO2 ¼ ðCO CaO2 Þ ðCO CvO2 Þ
Age, heart rate, gender dependenta
Flow Pulmonary
QP ¼
VO2 ðSPV O2 SPA O2 Þ Hgb 1:36 10
QS ¼
VO2 ðSAO O2 SMV O2 Þ Hgb 1:36 10
Systemic
Shunt flow ratio
Resistance Pulmonary
Systemic
QP SAO O2 SMV O2 ¼ Qs SPV O2 SPA O2 PVR ¼
PAP LAP OP
SVR ¼
AoP RAP QS
(lmin1m2) 3.5–5 3.5–5
1:1
(Woods unit) Newborns: 8–10 Older children: 1–3 Newborns: 10–15 Older children: 15–30
VO2 oxygen consumption; CO cardiac output; CaO2 arterial oxygen content; CvO2 venous oxygen content; QP pulmonary flow; QS systemic flow; SO2 oxygen saturation; PV pulmonary vein; PA pulmonary artery; Ao aorta; MV mixed venous; PVR pulmonary vascular resistance; PAP pulmonary artery pressure; LAP left atrial pressure; SVR systemic vascular resistance; AoP aortic pressure; RAP right atrial pressure. a LaFarge equation for VO2: Boys VO2 ¼ 138:1 ½11:49 loge ðage in yearsÞ þ 0:378 ðheart rateÞ Girls VO2 ¼ 138:1 ½17:04 loge ðage in yearsÞ þ 0:378 ðheart rateÞ
128
© 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
J.E. Lam et al.
Anesthesia and pediatric cardiac cath
or oxygen desaturation significant enough to require treatment or surgical intervention, or that result in neurologic complications, and/or permanent injuries. With the exception of isolated airway difficulties, it remains difficult to delineate what percentage of adverse events can be purely attributed to anesthesia or sedation. Vascular complications (32.4%) followed by arrhythmias (23%) are the most common pediatric cardiac catheterization complications (11). Thrombosis at the access site has an incidence of 0.8–8% (12–14). The Congenital Cardiac Catheterization Outcomes Project (C3PO) reviewed 3855 cases from six institutions over a 15-month period and determined that interventional cases carry the highest risk of adverse events (20%) when compared with diagnostic (10%) and biopsy (4%) studies (15). Data from an expanded C3PO registry with a cohort of 8905 cases over 36-months showed an incidence of life-threatening events to be 2.1% (16). Unsurprisingly, high severity adverse events occur with significantly greater frequency in interventional cases (11,15). Furthermore, the risk of cardiac arrest in children undergoing cardiac catheterization is higher when compared with pediatric non-cardiac surgery, with a single-center survey citing incidences of 0.96
Table 2 Classification of complications Classification Death Hemodynamic
Arrhythmia
Vascular Bleeding
Relating to catheter manipulation
Relating to interventional procedure Other
Examples
Cardiac arrest Hypotension Hypoxia Metabolic acidosis Bradycardia Supraventricular tachycardia Ventricular tachycardia/fibrillation Atrioventricular block Junctional rhythm ST-segment derangements Vascular thrombosis: arterial and venous Perforation, tears, avulsion Hematoma at catheterization site At other sites: hemothorax, retroperitoneal Cardiac perforation Cardiac tamponade Air embolus Wire complication: break, fixation, knot Device embolization Balloon rupture Respiratory events Infection Drug reactions Cerebral hypoperfusion/infarction Imaging equipment malfunction
© 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
per 100 catheterization procedures vs 0.8 per 100 surgeries, respectively (17). Identifiable risk factors for lifethreatening adverse events include age
REVIEW ARTICLE
Anesthesia and the pediatric cardiac catheterization suite: a review Jennifer E. Lam, Erica P. Lin, Ryan Alexy & Lori A. Aronson Department of Anesthesia/Cardiac Anesthesia, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
Keywords congenital heart disease; cardiac catheterization; anesthesia; children; sedation; complications Correspondence Dr. Jennifer E. Lam, Department of Anesthesia, Cardiac Anesthesia, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 2001, Cincinnati, OH 45229-3026, USA Email: [email protected] Section Editor: C. Dean Kurth Accepted 4 September 2014 doi:10.1111/pan.12551
Summary Advances in technology over the last couple of decades have caused a shift in pediatric cardiac catheterization from a primary focus on diagnostics to innovative therapeutic interventions. These improvements allow patients a wider range of nonsurgical options for treatment of congenital heart disease. However, these therapeutic modalities can entail higher risk in an already complex patient population, compounded by the added challenges inherent to the environment of the cardiac catheterization suite. Anesthesiologists caring for children with congenital heart disease must understand not only the pathophysiology of the disease but also the effects the anesthetics and interventions have on the patient in order to provide a safe perioperative course. It is the aim of this article to review the latest catheterization modalities offered to patients with congenital heart disease, describe the unique challenges presented in the cardiac catheterization suite, list the most common complications encountered during catheterization and finally, to review the literature regarding different anesthetic drugs used in the catheterization lab.
Introduction Innovations have shifted the scope of pediatric cardiac catheterization from a diagnostic tool towards therapeutic intervention (1,2). Advances in cardiac imaging and novel devices offer patients a wider range of nonsurgical options, possibly postponing or replacing surgical intervention. However, data from the Pediatric Perioperative Cardiac Arrest registry show that nearly one-third of cardiac arrests occur in children with congenital heart disease (CHD), of which 17% occur during cardiac catheterization (3). Thus, the anesthesiologist practicing in the catheterization suite must be familiar with CHD and the unique limitations that are specific to this environment. The cath lab The cardiac catheterization suite is a challenging environment. The physical isolation from additional anesthesia resources combined with limited functional space that hinders access to the patient can make emergency resuscitation more difficult (4). Medications and airway © 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
devices should be within easy reach. Expandable breathing circuits and intravenous tube extensions are often needed. Cardiac catheterization, especially cine fluoroscopy, delivers some of the highest doses of radiation with no known safe dose to mitigate cancer risk (5–8). Dosimeters should be worn to monitor cumulative radiation exposure. Personnel should adhere to three radiation safety principles to reduce occupational exposure: (i) maintain maximal distance from the source, (ii) minimize exposure time, and (iii) use proper shielding (e.g. wrap-around lead apron, thyroid collar, protective eyewear) (4). Mobile lead screens add further protection. Goals of catheterization Diagnostic catheterizations provide additional understanding of a patient’s anatomy, hemodynamics, myocardial function and/or responsiveness to medications and respiratory interventions. Hemodynamic data is often acquired in room air when dissolved oxygen is negligible and therefore not included in subsequent calculations of flow and resistance. If supplemental oxygen 127
J.E. Lam et al.
Anesthesia and pediatric cardiac cath
is administered, calculations must account for dissolved oxygen. Thus, communication between the anesthesiologist and cardiologist is crucial. Pulmonary flow (QP) and systemic flow (QS) can be calculated using the Fick principle, which states that flow is equal to the patient’s oxygen consumption divided by the difference in oxygen content across the vascular bed in question (Table 1). In patients without shunting, QP equals QS. Shunt defects, however, alter the QP:QS ratio. Pulmonary and systemic vascular resistances (PVR, SVR) are similarly calculated using Poiseuille’s equation, which relates resistance to vascular pressure divided by volumetric flow rate (Table 1). It should be noted, however, that this calculation is based on laminar vs turbulent flow and assumes a normal blood viscosity. Traditionally, oxygen consumption (VO2) is calculated based on heart rate, gender and age (from 3 to 40 years) using the LaFarge equation, but is less accurate in children 10 kg in conjunction with transesophageal echocardiography. More recent advancements in the field include transcatheter valve replacement. In CHD, these valves are most commonly placed in failing pulmonary bioprosthetic valves or right ventricle to pulmonary artery conduits. Large femoral sheaths are often needed for device deployment, and the resulting vascular access site may be closed by a percutaneous suture delivery device. Complications Causes for cardiac catheterization adverse events can be classified into eight main categories (Table 2) that can be further subdivided into minor and major events. Generally, minor events include those that are transient and resolve with or without treatment. The spectrum of major events includes death, cardiac arrest, hypotension
Table 1 Hemodynamic calculations using cardiac catheterization data Hemodynamic variable
Equation
Normal values
Oxygen consumption
VO2 ¼ ðCO CaO2 Þ ðCO CvO2 Þ
Age, heart rate, gender dependenta
Flow Pulmonary
QP ¼
VO2 ðSPV O2 SPA O2 Þ Hgb 1:36 10
QS ¼
VO2 ðSAO O2 SMV O2 Þ Hgb 1:36 10
Systemic
Shunt flow ratio
Resistance Pulmonary
Systemic
QP SAO O2 SMV O2 ¼ Qs SPV O2 SPA O2 PVR ¼
PAP LAP OP
SVR ¼
AoP RAP QS
(lmin1m2) 3.5–5 3.5–5
1:1
(Woods unit) Newborns: 8–10 Older children: 1–3 Newborns: 10–15 Older children: 15–30
VO2 oxygen consumption; CO cardiac output; CaO2 arterial oxygen content; CvO2 venous oxygen content; QP pulmonary flow; QS systemic flow; SO2 oxygen saturation; PV pulmonary vein; PA pulmonary artery; Ao aorta; MV mixed venous; PVR pulmonary vascular resistance; PAP pulmonary artery pressure; LAP left atrial pressure; SVR systemic vascular resistance; AoP aortic pressure; RAP right atrial pressure. a LaFarge equation for VO2: Boys VO2 ¼ 138:1 ½11:49 loge ðage in yearsÞ þ 0:378 ðheart rateÞ Girls VO2 ¼ 138:1 ½17:04 loge ðage in yearsÞ þ 0:378 ðheart rateÞ
128
© 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
J.E. Lam et al.
Anesthesia and pediatric cardiac cath
or oxygen desaturation significant enough to require treatment or surgical intervention, or that result in neurologic complications, and/or permanent injuries. With the exception of isolated airway difficulties, it remains difficult to delineate what percentage of adverse events can be purely attributed to anesthesia or sedation. Vascular complications (32.4%) followed by arrhythmias (23%) are the most common pediatric cardiac catheterization complications (11). Thrombosis at the access site has an incidence of 0.8–8% (12–14). The Congenital Cardiac Catheterization Outcomes Project (C3PO) reviewed 3855 cases from six institutions over a 15-month period and determined that interventional cases carry the highest risk of adverse events (20%) when compared with diagnostic (10%) and biopsy (4%) studies (15). Data from an expanded C3PO registry with a cohort of 8905 cases over 36-months showed an incidence of life-threatening events to be 2.1% (16). Unsurprisingly, high severity adverse events occur with significantly greater frequency in interventional cases (11,15). Furthermore, the risk of cardiac arrest in children undergoing cardiac catheterization is higher when compared with pediatric non-cardiac surgery, with a single-center survey citing incidences of 0.96
Table 2 Classification of complications Classification Death Hemodynamic
Arrhythmia
Vascular Bleeding
Relating to catheter manipulation
Relating to interventional procedure Other
Examples
Cardiac arrest Hypotension Hypoxia Metabolic acidosis Bradycardia Supraventricular tachycardia Ventricular tachycardia/fibrillation Atrioventricular block Junctional rhythm ST-segment derangements Vascular thrombosis: arterial and venous Perforation, tears, avulsion Hematoma at catheterization site At other sites: hemothorax, retroperitoneal Cardiac perforation Cardiac tamponade Air embolus Wire complication: break, fixation, knot Device embolization Balloon rupture Respiratory events Infection Drug reactions Cerebral hypoperfusion/infarction Imaging equipment malfunction
© 2014 John Wiley & Sons Ltd Pediatric Anesthesia 25 (2015) 127–134
per 100 catheterization procedures vs 0.8 per 100 surgeries, respectively (17). Identifiable risk factors for lifethreatening adverse events include age
