The following sections discuss imaging for some of the more common selected acquired cardiovascular diseases, including trauma, coronary artery abnormalities, myocarditis/cardiomyopathy, and systemic vasculopathy and vasculitides.

Cardiovascular injuries are one of the most common causes of death secondary to trauma, only second to injuries to the central nervous system [46, 47]. Prompt identification and management of critical injuries is paramount to improve survival rate [47]. Cardiovascular trauma can be classified into two major categories: penetrating and blunt thoracic injury. Pediatric cardiac trauma is most commonly due to blunt mechanisms, and these are more frequently secondary to motor vehicle accidents and falls [46, 48,49,50,51]. We will focus our discussion on blunt thoracic injury.

Pediatric traumatic chest injuries differ as compared to adults. Children have increased thoracic cage flexibility and compressibility allowing higher deformity of the chest cage. Also, children have increased mobility of the cardiomediastinal structures [50]. These features lead to an increased risk for pulmonary contusions, but less commonly fractures, and, even rarer, aortic injury. Nonetheless, there is approximately 27–40% mortality rate after cardiac injury in children [50].

The mechanisms of injury to the cardiovascular structures due to blunt thoracic injury include direct impact to the precordium with compression of the heart between the sternum and the spine, blast injury, injury due to fractures, or tension pneumothorax. Other mechanisms are due to indirect forces secondary to abdominal trauma, with shearing or displacement of the cardiovascular structures, force injuries transmitted from lower extremity injuries, or due to cardiovolemic change with increased vascular pressure transmitted to the heart [46, 47].

Patients with chest trauma may present with an abnormal ECG and/or abnormal cardiac enzymes [46, 47]. Findings on radiographs can include pneumopericardium, pericardial effusion with enlargement of the cardiac contour, hydrothorax, hemothorax, pneumothorax, and mediastinal widening, suggesting a hematoma or vascular injury. Echocardiography can demonstrate pericardial effusion, signs of cardiac tamponade, valve dysfunction, or wall motion abnormalities [46, 47]. Contrast-enhanced CT is the gold standard and first-line imaging modality in traumatic cardiovascular injury. Spectrum of CT imaging findings include pneumopericardium, pericardial effusion or hemopericardium, pericardial rupture, myocardial contusion, myocardial tears, cardiac tamponade, cardiac herniation, valve injuries, vascular injuries, or signs of pressure change with right heart strain [52]. Other findings include mediastinal hematomas and other non-cardiovascular findings such as rib or sternal fractures, lung and pleural space findings (Fig. 9), or abdominal or lower extremities injures, translating into cardiovascular injuries [47].

Traumatic non-cardiovascular findings. a Anteroposterior chest radiograph in a 9-year-old boy obtained in the trauma bay demonstrates a mild widening of the upper mediastinum with hazy ill-defined increased paramediastinal opacification. The patient is intubated with a feeding tube in place. External devices are obscuring details. b A 12-year-old girl where an axial contrast-enhanced computed tomography (CT) shows a large mediastinal hematoma (arrow) and consolidations/atelectasis in the dependent aspects of both lungs. c A 10-year-old boy with a contrast-enhanced CT showing a large mediastinal hematoma (asterisk) with active bleed (arrow). Cases courtesy of Dr. David Manson from The Hospital for Sick Children, Toronto, Canada

Pericardial effusion may occur after acute traumatic injury and in this setting, any pericardial effusion should be considered hemopericardium until proven otherwise [52]. Hemopericardium is usually associated with cardiac chamber rupture and has a high mortality rate, but also can be due to aortic root injury, a myocardial contusion or coronary artery dissection (Fig. 10) [46]. Pericardial rupture is rare, seen in about 0.3–0.5% after traumatic injury, and is usually secondary to fractures or deceleration forces [52]. CT can show discontinuity of the pericardium with focal dimpling, pneumopericardium, an empty pericardial sac, cardiac contour or cardiac chamber constriction or deformity, or cardiac luxation [46].

A 12-year-old boy with hemopericardium. Axial contrast-enhanced computed tomography of the thorax demonstrates high density pericardial fluid (asterisk) consistent with hemopericardium. Note also a small mediastinal hematoma (arrow) and consolidation/atelectasis of the posterior lungs, more confluent on the left. Courtesy of Dr. David Manson from The Hospital for Sick Children, Toronto, Canada

Cardiac tamponade results from accumulation of pericardial fluid or hemopericardium, compressing the heart and leading to a decrease in cardiac output, or due to a mediastinal hematoma. Imaging findings include hemopericardium, jugular vein congestion, dilatation of the inferior vena cava and renal veins, and periportal low attenuation fluid [46]. There may be late onset of cardiac tamponade with minor blunt chest trauma in children [53].

The myocardium can be injured from direct impact of the heart against the osseous structures, or due to shearing forces [47]. Myocardial concussions show no anatomic or cellular injury, but echocardiography can show focal wall motion abnormalities. Myocardial contusions cause anatomic or tissue injury, and can lead to myocardial infarction and elevated cardiac enzymes. Imaging findings can include pneumopericardium, signs of congestive heart failure with pulmonary edema and lung opacities [46]. Echocardiography shows focal increased myocardial echogenicity and systolic hypokinesia [46]. Associated findings include traumatic valvular injuries and ventricular septal defects. Due to its position in the chest, the right ventricle free wall is more frequently injured [46, 47]. Right ventricular injury can cause contractility impairment, and hypovolemia can cause decreased left ventricular preload output.

Myocardial tears are an uncommon cause of immediate death after blunt trauma and are a cause of cardiac tamponade and fatal arrhythmias [47, 54]. CT can show focal discontinuity and active contrast extravasation into the pericardial space [47, 55].

Posttraumatic left ventricular aneurysm, although rare, has been described in children, along with other findings, such as interventricular septal aneurysm and traumatic VSD [48]. Patients can present with features of heart failure, emboli, arrhythmias, and palpitations [48]. Traumatic VSDs are the most frequent traumatic septal injury [47]. These usually occur within a site of a myocardial contusion, near the cardiac apex, in the muscular portion of the interventricular septum [46]. Traumatic VSDs can be seen early immediately after trauma due to mechanical compression, or late when edema disrupts the muscle perfusion with eventual perforation. Traumatic VSD and ventricular aneurysm have also been described in children after blunt injury due to child abuse [56].

Valvular injury can also occur, and due to the higher pressure of the left cardiac chambers, the mitral and aortic valves are at increased risk of injury with valve cusp avulsion or tear [47, 52].

Coronary artery injuries are unusual, seen in approximately 2% after traumatic blunt thoracic injuries. When this occurs, the left anterior descending artery is more frequently injured [47, 57].

Aortic injury is rarely seen in children due to the increased elasticity of the pediatric arterial structures, but can be seen in about 0.05–7.4%, and approximately 90% of children with aortic injury are older than 10 years of age [51, 58]. These are associated with a high mortality rate of about 85% [58]. Aortic injuries frequently occur at the level of the ligamentum arteriosum and include an intimal tear (type I), an intramural hematoma (type II), an aortic pseudoaneurysm (type III) (Fig. 11), and aortic rupture (type IV) [59]. Other findings can include a periaortic hematoma, intimal flaps, vessel wall irregularity or caliber change, vessel occlusion, or active contrast extravasation [60]. In children, an aortic laceration can be seen in less than 0.1% after blunt thoracic injury [50, 61,62,63]. Traumatic aortic dissection may not be as uncommon in childhood or adolescence, with a study reporting aortic dissection in up to 42% [64]. Pulmonary artery trunk injury is very rare [47].

An 8-year-old boy with aortic pseudoaneurysm. a Contrast-enhanced computed tomography of the chest demonstrates a pseudoaneurysm in the proximal descending aorta (arrows). Bilateral consolidation/atelectasis is also noted in both lungs posteriorly. b Lateral view of digital subtraction aortic angiography demonstrates a traumatic pseudoaneurysm in the proximal descending aorta. Cases courtesy of Dr. David Manson from The Hospital for Sick Children, Toronto, Canada

Cardiac luxation or herniation refers to disruption of the cardiac axis or displacement of the heart in the chest (Fig. 12) causing constriction or cardiac torsion. It is the most lethal complication secondary to pericardial rupture with a high mortality rate [46, 47]. Imaging findings include malposition of the heart, bowel herniating into the pericardial sac, or an empty pericardial sac with pneumopericardium [46, 47].

A 16-year-old boy with cardiac displacement due to diaphragmatic rupture. a Anteroposterior chest radiograph with electrodes over the thorax. (b) Coronal plane of a contrast-enhanced computed tomography (CT) with a chest tube in the left thorax and (c) CT in an axial plane. All images demonstrate displacement of the cardiomediastinal structures due to diaphragmatic rupture with herniation of the abdominal contents into the left hemithorax

Coronary artery assessment is one of the most common indications for urgent cardiac imaging. ECG-gated cardiac CT will almost always be the modality of choice in these situations. Some typical indications include infants with suspected anomalous left/right coronary artery from the pulmonary artery, children post cardiac arrest due to a suspected cardiac cause such as anomalous aortic origin of a coronary artery, patients with an underlying vasculopathy or vasculitis (particularly in Williams syndrome) presenting with new findings or symptoms, or in postoperative patients after coronary reimplantation with persistent ventricular dysfunction or turbulent coronary origin flow by Doppler (e.g., after arterial switch or Ross operations). Occasionally, tubes and devices can also compress or impinge on a coronary artery in postoperative patients with persisting ventricular dysfunction. A few pearls regarding specific scenarios follow.

Anomalous left coronary artery from the pulmonary artery is a classic differential consideration in an infant with ventricular dysfunction and heart failure, showing cardiomegaly and pulmonary venous congestion/edema on chest radiographs. The anomalous left coronary artery often arises from the undersurface of the main pulmonary artery (Fig. 13). Because of the lower pressure pulmonary circulation, there is “retrograde” flow from the left coronary artery into the main pulmonary artery, resulting in a left-to-right steal phenomenon and subsequent ischemia. Intrinsic left coronary artery ostial stenosis and right coronary artery, systemic, and bronchial collateralization can mitigate these effects to a degree [65]. The anatomy can often be diagnosed by echocardiography, but in select patients, feed-and-sleep cardiac CT may be required for confirmation of diagnosis.

A 9-week-old boy with anomalous origin of the left coronary artery from the pulmonary artery who presented in cardiogenic shock. a Anteroposterior chest radiograph shows moderate to severe cardiomegaly with pulmonary edema. An endotracheal tube is near the carina and a nasogastric tube is in the stomach. b-d Coronal (b) and sagittal (c) contrast-enhanced cardiac computed tomography maximum intensity projection and volume rendering technique reconstructions (d), show the left main coronary artery (LMCA) arising from the undersurface of the main pulmonary artery (MPA) (arrows). This patient also has a fine network of collaterals surrounding the LMCA. Note: the dilated left ventricle (LV) due to ischemic cardiomyopathy. Ao aorta, LA left atrium

One of the considerations after new cardiac arrest in older children and teenagers is anomalous aortic origin of a coronary artery. Sudden cardiac events in anomalous aortic origin of a coronary artery typically occur during exertion and more commonly are due to an anomalous left coronary artery from the right aortic sinus. Anomalous right coronary artery from the left aortic sinus is more prevalent overall, but less likely to be symptomatic [66]. A septal coronary course has historically been considered a relatively benign variant, but recently it has been shown that up to 50% of these patients may have inducible myocardial hypoperfusion [67]. Retroaortic and pre-pulmonic coronaries are still considered relatively benign. Some of the more important reporting elements include presence and length of any intramural segment, ostial morphology, and relationship to the aortic valve commissure and intercoronary pillar (Fig. 14).

A 12 -year-old boy with an anomalous origin of the left coronary artery from the right aortic sinus who suffered a cardiac arrest while playing basketball. a, b Multiplanar oblique contrast-enhanced cardiac computed tomography (CT) reconstructions show the anomalous origin of the left main coronary artery from the right aortic sinus arising at an acute angulation with an interarterial course. There is a very thin poorly opacified intramural segment (arrows) that crosses across the right-left aortic commissure. c Coronal cardiac CT reconstruction shows the interarterial portion in cross section (arrow), which is slit-like with loss of pericoronary fat, typical signs of an intramural segment

Concerns for coronary stenosis in infants with vasculopathy or in the postoperative setting after coronary reimplantation may necessitate an urgent cardiac CT for further evaluation. Even in small infants with high heart rates where the spatial and temporal resolution is limited, it is often worthwhile to attempt to visualize the coronaries before deciding if the more invasive gold-standard test of cardiac catheterization requiring general anesthesia should be pursued. This is particularly true in Williams syndrome due to the high risk of sudden death with sedation in these patients [68]. Williams syndrome is caused by an elastin gene mutation that causes arterial media wall thickening and stiffening due to smooth muscle hypertrophy and results in multifocal arterial stenoses. This classically manifests as a characteristic supravalvular aortic stenosis seen in up to 70% of patients, along with peripheral branch pulmonary artery stenoses that can affect 40–75% of patients. The coronaries can be involved in association with the supravalvular stenosis, separately via intrinsic focal ostial stenosis, or indirectly via aortic valve leaflet degeneration and supravalvular tethering in a phenomenon known as “coronary hooding” [69].

Coronary ostial stenosis is also a risk whenever the coronaries are reimplanted, such as after an arterial switch operation or Ross procedure. Urgent cardiac CT may be required in the immediate postoperative period when there is persistent ventricular dysfunction or coronary concerns by echocardiography. Visualization of the coronary origins by cardiac CT is often useful to show or exclude significant proximal coronary stenosis, kinking, or stretching. Coronary assessment by cardiac CT can be particularly successful after arterial switch operation, as in these patients the coronaries are typically reimplanted higher in the neoaorta, which is a region less susceptible to cardiac motion.

The diagnosis of viral myocarditis in the pediatric population can usually be made based on clinical, ECG, serologic, and echocardiographic findings alone. CMR is indicated when the diagnosis is in doubt and for potential prognostication [9] and can be obtained in the semi-urgent acute setting after patients are stable. The most important diagnosis to exclude is acute coronary ischemia; however, congenital cardiomyopathy and other rheumatologic, granulomatous, or neoplastic causes of myocardial inflammation can also rarely mimic typical viral myocarditis. This picture has been even more complicated with the recent rise of myocarditis due to coronavirus disease-19 (COVID-19), COVID-19 vaccine-adjacent myocarditis, and multisystemic inflammatory disease in children (MIS-C) myocarditis (± coronary involvement). Our understanding of COVID-19-related myocardial injury is continuing to evolve and a detailed review is beyond the scope of this article.

The modified Lake Louise diagnostic criteria for myocarditis are the presence of (1) myocardial edema via T2-mapping or T2-weighted images and (2) non-ischemic myocardial injury via T1-mapping or late gadolinium enhancement. Supportive criteria include evidence of pericarditis and findings of pericardial effusion or ventricular dysfunction [70]. An ischemic cause must be suspected when the late gadolinium enhancement pattern is subendocardial or transmural and confined to a coronary perfusion territory (Fig. 15). If there is any clinical possibility of either an ischemic cause or MIS-C, coronary magnetic resonance angiography should be included in the protocol. Using a gadolinium-enhanced, cardiac-gated, respiratory-navigated, 3D inversion recovery gradient echo (GRE) sequence for both coronary magnetic resonance angiography and late gadolinium enhancement can be very useful in this scenario [71,72,73].

An 11-year-old boy with a myocardial infarction who presented in hypertensive crisis with cardiac dysfunction, initially suspected to be an infectious or inflammatory myocarditis. a Short-axis magnetic resonance 3-dimensional high-resolution late gadolinium enhancement reconstructions show irregular wall thickening and enhancement of the right coronary artery (arrow), suggestive of a coronary vasculitis. b There is also transmural late gadolinium enhancement in the left anterior descending (LAD) territory (arrowheads) with significant central subendocardial microvascular obstruction (short arrow), consistent with a myocardial infarction. The LAD itself was not able to be well visualized (not shown). c Subsequent right anterior oblique cardiac catheterization projection shows a wire bypassing a proximal LAD occlusion

Systemic vasculopathies and vasculitides may occasionally require acute imaging for complications of the disease. Of the inherited vasculopathies, the entities of connective tissue disorders most commonly present with acute complications. These include Marfan syndrome, Loeys-Dietz syndrome, and vascular Ehlers-Danlos syndrome. Loeys-Dietz syndrome is an autosomal dominant connective tissue disorder caused by dysregulation of transforming growth factor beta (TGF-β). Vascular features of Loeys-Dietz syndrome include aggressive arterial tortuosity and development of aneurysms (Fig. 16), which can occur beyond the aortic root (unlike Marfan syndrome). Loeys-Dietz syndrome has a higher risk of dissection and rupture, which can occur at smaller sizes. The vertebral tortuosity index, which is a ratio of the vertebral artery length to straight-line cranio-caudal length, is an imaging biomarker for cardiovascular prognosis in connective tissue disorders and is particularly useful for Loeys-Dietz syndrome [74]. Ehlers-Danlos syndrome encompasses a spectrum of genetic disorders with underlying defective collagen synthesis. Vascular Ehlers-Danlos syndrome mainly affects the large and medium systemic arteries. The vessels in vascular Ehlers-Danlos syndrome are extremely friable and very susceptible to the development of pseudoaneurysms and dissections regardless of size, making these children incredibly difficult to manage. Even minor trauma can lead to injury and any intervention can be complicated by additional aneurysms, rupture, or dissection [75].

A 4-year-old boy with Loeys-Dietz syndrome complicated by aortic dissection. a Contrast-enhanced computed tomography (CT) parasagittal-oblique volume rendering projection shows a dilated and tortuous aorta, along with severe tortuosity of the head and neck vessels, especially of the vertebral arteries. b, c Axial (b) and coronal (c) CT images 4 years later show an aortic dissection flap (arrows) extending from the ascending aorta to infrarenal abdominal aorta, consistent with a type-A dissection

The most common vasculitides to affect the pediatric population are Takayasu arteritis and Kawasaki disease. Takayasu arteritis is a chronic idiopathic granulomatous large vessel vasculitis that predominantly affects the aorta and major branches. It most commonly results in stenoses, but can also cause complete occlusions, aneurysms, and dissections. Childhood Takayasu has high morbidity with greater involvement of the abdominal aorta than in adults. Hypertension, which is mainly renovascular, is present in 70–80% of pediatric patients, and 10–35% of children have lower limb claudication [76]. Imaging will show vessel wall thickening, edema, and enhancement. Kawasaki disease is a small- and medium-sized vessel vasculitis that presents in early childhood. The most serious complication of Kawasaki disease is a coronary arteritis that can cause coronary aneurysms and lead to thrombus and stenoses. Myocardial infarction can occur even many years after the disease and concern for acute coronary syndrome may require acute cross-sectional imaging [77]. On long-term surveillance, the affected coronary arteries typically have persistent hyperenhancement, which could potentially be related to chronic luminal myofibroblastic proliferation and/or fibrosis.