Eur J Cardiothorac Surg 1999;16:679-682
© 1999 Elsevier Science NL
Atrioventricular septal defect following blunt chest trauma
Mário Jorge Amorim,
Jorge Almeida,
Albino Santos,
Pedro Teixeira Bastos
Center of Thoracic Surgery, S. João Hospital, Oporto, Portugal
Corresponding author. Tel.: +351-2-550-2417; fax: +351-2-550-2254
e-mail: mjamorim.casa{at}teleweb.pt
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Abstract
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The authors describe an acquired atrioventricular septal defect that has resulted from a blunt chest trauma. Besides being an uncommon traumatic heart injury, this case has the particularities of the non-involvement of other adjacent anatomical structures and the long delay between the accident and the occurrence of the myocardial rupture.
Key Words: Acquired atrioventricular septal defect • Blunt cardiac trauma • Echocardiography in the evaluation of blunt chest trauma
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1. Introduction
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The possibility of a traumatic cardiovascular lesion must be always considered when we are dealing with a patient who has suffered a violent closed chest trauma. To discharge this possibility a close clinical evaluation, EKG monitoring and echo examinations are mandatory in the management of these patients [1].
Myocardial concussion characterized by an elevation of specific myocardial creatine phosphoquinase enzymes (CPK MB) without detectable structural or functional cardiac injury is the most common lesion. However, major and life-threatening injuries of cardiac and vascular structures can occur and should be carefully screened in the victims of blunt chest trauma. Echocardiography, including transthoracic (TTE) and transesophageal (TEE) approaches [2,3], is the leading tool in the evaluation of the nature and extension of such traumatic cardiac lesions.
The authors report a case of a traumatic atrioventricular (AV) septal defect in a 16-year-old male resulting from of a violent car crash. Besides being an uncommon lesion, this case has the particularities of the long delay on the emerging of the defect and the fact that the neighbor structures have been spared.
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2. Case report
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A 16-year-old Caucasian male, who had suffered a violent car crash with multiple organ trauma, was admitted to the intensive care unit (ICU). The patient was in coma (8 in Glasgow scale). A right hemopneumothorax, extensive bilateral pulmonary contusion, mediastinal hematoma and multiple bone fractures were diagnosed on the initial evaluation. On the evidence of a mediastinal hematoma in the tomographic study a TTE and a TEE were also performed and no cardiac lesion or pericardial effusion were evident.
Eleven days after the admission, on the suspicion of a cardiac tamponade, a TTE showed a large pericardial effusion. A pericardiocentesis was performed with drainage of 500 ml of blood. Two days later, however, a new TTE showed recurrence of the pericardial effusion. Despite the fact that no structural abnormalities had been identified by echocardiography it was decided to perform an exploratory sternotomy. During the procedure a large (1100 ml) loculated serohematic effusion was drained. The only cardiac lesion detected was a contusion of the left atrial appendage.
No cardiac conduction disturbances or other arrhythmias were reported during his stay in the ICU. Having totally recovered from the pleuro-pulmonary and neurological lesions the patient was discharged from the hospital 48 days after the admission date.
On a follow-up observation 35 days after the discharge the patient complained of fatigue and dyspnea. Clinical examination revealed a new cardiac, grade IV/VI, harsh holosystolic murmur with a normal EKG. A TTE was performed and an anomalous flux between the left ventricle and the right atrium led to the suspicion of a traumatic atrioventricular rupture a diagnosis later confirmed by TEE (Fig. 1). Cardiac catheterization showed a mildly elevated pulmonary arterial pressure (35/10, mean 20 mm Hg) with a left to right shunt calculated at 2.2:1. The left ventriculography confirmed the abnormal left ventricle to right atrium communication.
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Fig. 1. Transesophageal echocardiogram of the AV defect. The arrow points to the site of the defect. On the Doppler image a turbulent flow is observed inside the right atrium. LA, left atrium; LV, left ventricle; RA, right atrium, RV, right ventricle.
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Considering the symptoms on the setting of a significant left to right shunt the patient was referred for surgical correction. At surgery the heart was exposed through a midline sternotomy. A 1-cm defect was seen in the atrial component of the AV septum just above the insertion of the septal leaflet of the tricuspid valve (Fig. 2). The defect was closed with a Gore Tex® patch under TEE control. The postoperative period was complicated by complete AV block and a DDD pacemaker was implanted before hospital discharge.
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Fig. 2. Anatomical view of the AV septum through right atriotomy. A defect about 1 cm large is observed above the septal leaflet of the tricuspid valve (a tweezers is inserted through the defect).
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On follow-up consultation three months after surgery the patient had no cardiac symptoms, no heart murmur was audible and no anomalies were detected by TTE. The EKG showed now the presence of sinus rhythm with a normal AV conduction.
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3. Discussion
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Rupture of the AV septum is an uncommon traumatic lesion. In the few cases reported in medical literature the diagnosis was made at autopsy [4], at cardiac catheterization [5,6] or non-invasively by echocardiography [7–9].
The AV septum, a small area of the membranous portion of the ventricular septum that separates the left ventricle from the right atrium, is in close proximity to the septal tricuspid, the aortic sinus and the atrioventricular conduction system. This intimate relationship explains the usual involvement of one or more of these structures on traumatic lesions of AV septum.
The septal rupture is considered to occur due to compression of the ventricular septum in end-diastole (immediately following atrial contraction) or during isovolumetric systole, when the cardiac valves are closed and the ventricles are filled with blood. Parmley et al. [10] postulate that septal injury causes initial edema, followed by liquefaction necrosis and appearance of a true defect. This sequence of events could explain the delay in the occurrence of the septal defect. According to the published papers, the time elapsed between the accident and the diagnosis of the rupture has varied between hours or days [5–10].
Like the previous reported cases of traumatic AV rupture, this case also occurred in a young male in the context of a violent chest trauma. However, our report presents some singularities that deserve to be enhanced:
- To the best of our knowledge this is the first case of traumatic AV rupture diagnosed in a living without involvement of the neighboring anatomical structures. All the previous cases of AV rupture diagnosed antemortem report associated lesions of the conduction system [5,8,9] , the tricuspid valve [6,7], or the aortic sinus [8].
- Another particularity is the long delay between the acute accident and the time of the myocardial AV rupture. Although we cannot precise the date, we know that it occurred somewhere between the second and the third month after the accident as no cardiac murmur was reported at the time the patient was discharged from the hospital.
Spontaneous recover of the AV conduction suggests that the complete AV block resulted from surgical mechanical trauma.
We conclude alerting for the necessity of a careful medical survey of patients who have been victims of a violent blunt chest trauma even if no major cardiac lesions were detected in the acute phase of the accident.
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References
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Received June 29, 1999;
received in revised form September 13, 1999;
accepted October 5, 1999.
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Abstract
1. Introduction
