Pediatric emergency medicine trisk 928
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cardiac injury will have neither symptoms nor abnormal physical examination
findings, and therefore a high index of suspicion is required when the mechanism
of injury makes cardiac injury possible.
FIGURE 115.5 Bedside ultrasound showing large pericardial effusion surrounding the heart.
Pericardial tamponade may initially be difficult to diagnose because of
associated injuries obscuring the clinical signs and symptoms. Patients may
present with distant heart sounds, low blood pressure, poor perfusion, a narrow
pulse pressure, or electromechanical dissociation. Pulsus paradoxus, blood
pressure falling more than 10 mm Hg during inspiration, occurs in less than onehalf of patients with pericardial tamponade and should not be relied on to make
the diagnosis.
Management
The evaluation for suspected blunt cardiac injury includes EKG, serum cardiac
troponin, echocardiography, and observation with continuous cardiac monitoring.
A 12-lead EKG may show ST-T-wave changes or arrhythmias. The combination
of a normal EKG and negative troponin is highly sensitive for ruling out
myocardial contusion or other significant blunt cardiac injury. For patients with
an abnormal EKG, elevated cardiac enzymes, or new findings on physical
examination, echocardiography should be performed.
There is no specific therapy for myocardial contusion, other than treatment of
any resultant arrhythmia and circulatory support as necessary. More significant
blunt cardiac injuries, such as disruption of the atria, ventricle, or valves require
emergent surgical repair.
In the unstable patient in whom pericardial tamponade is suspected, treatment
includes control of the airway, intravascular volume resuscitation, and immediate
pericardiocentesis ( Fig. 115.6 ). Bedside US may assist in both diagnosis and
management and can often be performed concurrently with the physical
examination. A US showing a large pericardial effusion in the clinical context of
tamponade physiology should be sufficient to proceed with pericardiocentesis;
additional findings, including diminished or paradoxical septal wall motion and
poor cardiac output, may be evident to the more experienced sonographer.
Pericardiocentesis is performed by inserting a 20-gauge spinal needle below
the xiphoid process at a 45-degree angle toward the left shoulder ( Fig. 115.7 ).
Dynamic US guidance can help assure proper placement of the needle.
Continuous EKG monitoring can be used as well, as a current should be noted on
the EKG monitor if the needle touches the heart. Blood aspirated from the
pericardial sac can be differentiated from intracardiac blood because pericardial
blood is defibrinated and does not clot. Alternatively, pigtail catheters can be
placed into the pericardial sac over a guidewire for continual drainage of blood
using commercially available equipment kits designed for this purpose. Even
though patients may show transient improvement after removal of blood from the
pericardial sac, the patient should be taken to the operating room immediately for
a pericardial window or other surgical intervention (see Chapters 130 Procedures,
section on Pericardiocentesis , and 131 Ultrasound ).
For the stable patient with suspected pericardial tamponade, echocardiogram is
the study of choice. CXR may show an enlarged heart and an EKG may show
low-voltage QRS waves. While these patients will also require pericardiocentesis,
consultation with the pediatric trauma surgery team, cardiac surgeon, and/or
interventional cardiologist to perform this in the operating room or cardiac
catheterization laboratory is recommended provided the patient’s clinical
condition allows time for these resources to be mobilized.
FIGURE 115.6 Algorithm for the evaluation and diagnosis of pericardial tamponade.
FIGURE 115.7 Pericardiocentesis is performed by inserting a 20-gauge spinal needle below
the xiphoid process at a 45-degree angle toward the left shoulder.
Disposition
In one study, all children who developed heart failure or life-threatening cardiac
arrhythmias during their hospital course initially presented to the ED either in
shock or with an arrhythmia. Based on this, patients with suspected isolated
myocardial contusion can be monitored in the ED or hospital. If no arrhythmias
develop on EKG, they can be safely discharged home. Children with any
arrhythmia require admission to a bed with continuous cardiac monitoring. More
significant cardiac injuries necessitate admission to an intensive care unit, with
interventional cardiologists or cardiac surgeons available to provide emergent
interventions as needed.
INJURIES OF THE AORTA AND GREAT VESSELS
CLINICAL PEARLS AND PITFALLS
