M Ali Ostovan, R Mollazadeh
congenital absence of pericardium, pericardium, straight back syndrome
M Ali Ostovan, R Mollazadeh. Congenital Absence of Pericardium and Straight Back Syndrome: Do They Have Similarities?. The Internet Journal of Cardiology. 2006 Volume 4 Number 2.
The straight back syndrome, consisting of loss of normal upper thoracic spinal curvature is not an uncommon entity. In contrary congenital defects of the pericardium is a rare disease (1/10000 autopsies).In this report we present a case presented with chest pain whom after initial work up was presumed to have congenital absence of pericardium but further investigation uncovered the diagnosis as straight back syndrome. Here in we review the literature for the possible similarities between these two entities and the possible reason for our first misdiagnosis.
The straight back syndrome, consisting of loss of normal upper thoracic spinal curvature associated with cardiac murmurs which was previously considered a form of ‘pseudo heart disease' ,has been attributed to squashing of the heart in the reduced anteroposterior diameter of the chest1.On the other hand complete or partial absence of the pericardium is an uncommon congenital anomaly with various complications and presentations 2.Herein we report a young girl who presented with chest pain and dyspnoea,whom we thought to have congenital absence of pericardium primarily but later found to suffer from straight back syndrome.
A 16-year-old girl with no previous cardiac problems came to the outpatient clinic with ill-defined chest pain. She declared that she had this pain for many months. She complained of dyspnoea but not easy fatigability. Her cardiac examination was completely normal. Her electrocardiogram showed poor R wave progression. Postero-anterior chest -X ray showed cardiac levoposition with borderline cardiac size (Figure1).
Unusual echocardiographic views (Figure2) and paradoxical septal motions (Figure3) during transthoracic echocardiography augmented the suspicion of congenital absence of pericardium, so magnetic resonance imaging was performed. Contrary to our expectation, pericardial contour was intact (Figure 4).
RA: Right Atrium, RV: Right Ventricle, LA: Left Atrium, LV: Left Ventricle
A thorough physical re – examination revealed flat back; a lateral chest x-ray confirmed the presence of obliteration of thoracic kyphosis of the spine.
Except for one report of coexistence of congenital absence of pericardium and straight back syndrome3, these two entities seem to be unrelated. Herein we review the literature for their similarities and differences
Congenital pericardial absence is due to premature atrophy of the left common cardiac vein with insufficient blood supply to the pleuropericardium leading to its agenesis. Male/female ratio is 3:1 .This entity was described in the context of different syndromes4,5,6,7. HLA typing in straight back syndrome indicates that it is inherited as an autosomal dominant condition and suggested that the antigenic determinants may be located on chromosome 61.
Congenital absence of the pericardium is an uncommon finding ((1/10,000 in autopsies) comprise partial left (70%), partial right (17%) or total bilateral (extremely rare) pericardial absence2). Most patients are asymptomatic are discovered incidentally during cardiac surgery for an unrelated condition or at postmortem examination. Symptomatic patients may experience non-exertional paroxysmal stabbing chest pain 8. However homolateral cardiac displacement and augmented heart mobility impose an increased risk for traumatic aortic dissection9. Partial left sided defects can be complicated by cardiac strangulation caused by herniation of the left atrial appendage, atrium or ventricle through the defect (chest pain, shortness of breath, syncope, or sudden death). About 30% of patients have additional congenital abnormalities4,5,6,7.Partial absence of pericardium is often associated with other cardiac anomalies including atrial septal defect ,bicuspid aortic valve ,mitral valve stenosis, patent ductus arteriosus , tetralogy of Fallot or pulmonary malformation. Coexistence with recurrent pulmonary infections2 and endocarditis10 are also reported.
On the contrary, straight back syndrome usually comes to attention due to cardiac murmurs. Referring diagnosis include atrial septal defect, pulmonic stenosis and rheumatic heart disease. In one study half the patients were asymptomatic; others had dyspnea after brisk effort, palpitation and atypical chest pain11.
In patients suffering from pericardial absence clinical examination may show a significantly displaced apical impulse, which may be palpated in the anterior or midaxillary line. Basal ejection murmurs, apical midsystolic clicks and murmurs may also be found. Increased splitting of the second heart sound may be due to the presence of a right bundle branch block that is frequently associated with this defect12.
In straight back syndrome decrease in antero-posterior chest dimensions due to loss of thoracic kyphosis. Other findings in order of frequency are: palpable pulmonary artery pulsation, ejection systolic murmurs in pulmonic area, palpable impulse in left lower sternal border, accentuation and delay in tricuspid valve closure, exaggerated inspiratory splitting of the second heart sound, increase in amplitude of aortic and pulmonary closure. None of patients had thrill in pulmonic area nor did any of them have diastolic murmurs11.Apical systolic click and murmurs are usually due to coexistent mitral valve prolapse 13.
Electrocardiographic manifestations of pericardial absence are: bradycardia, right bundle branch block, poor R-wave progression secondary to leftward displacement of the precordial transitional zone, and prominent P-waves in the mid-precordial leads which denote right atrial overload8.
ECG manifestations of straight back syndrome are right bundle branch block in V1 and small terminal r waves in aVR 11.
Chest –X ray
Chest X-ray findings due to pericardial absence are levoposition of the heart, flattening and elongation of the left ventricular border, and a lucent area between the diaphragm and the heart, or aorta and pulmonary artery due to lung interposition.
Surprisingly patients with straight back syndrome may have some findings in the Chest X ray: pancake appearance simulating cardiomegaly, levoposition of heart, prominence of the main pulmonary artery13. In all patients both the antero-posterior diameter and the ratio of antero-posterior to transthoracic diameter were below the normal mean 11. On the lateral chest radiograph the distance from the middle of the anterior border T8 to a vertical line connecting T4 and T12 was found to be significantly reduced compared to controls, and a value less than 1·2 cm is the established criteria for straight back1.
Due to pericardial absence heart forms a “teardrop” appearance due to elongated atria and relatively bulbous ventricles because of suspension of the heart from its basal pedicle14. Findings in order of decreasing frequency are: unusual windows (a higher and more lateral window is required), cardiac hypermobility (cardioptosis), abnormal swinging motion, paradoxical or flat systolic motion of the ventricular septum with normal systolic thickening 15. Right ventricular overload with reduction in right atrial dimension may be evident with decreased tricuspid valve excursion. Increased diastolic wave velocities in both the superior vena cava and pulmonary veins on Doppler examination with decreased caval systolic wave velocity suggest accentuation of changes in systemic over pulmonary venous return16 (esp. in partial defects).
Echocardiograms were normal in 36% and abnormal in 64% of patients (mitral valve prolapse (MVP) in (58%) and bicuspid aortic valve in (6%)) of patients with straight back syndrome13. Strong association of MVP with this syndrome was proposed previously17.One of the important issues on the long-axis view of tomographic echocardiography is the aorto-septal angle of patients with straight back syndrome which was wide and thought to be due to clockwise rotation of the heart rather than right ventricular enlargement18.
ECG -gated MRI and spiral chest CT-scan are two other diagnostic tools to diagnose pericardial absence19.ECG gated T1 weighted spin echo magnetic resonance image is highly sensitive and is capable of demonstrating the absence of the preaortic pericardial recess in pericardial absence which is present in normal hearts8,19.
Complete cases of pericardial absence require no intervention unless complications occur. Patients with debilitating symptoms may benefit from pericardioplasty. However, in partial defects, when herniation occurs or is threatened, extension of the defect by the pericardiectomy, or pericardioplasty may be preformed2,8 but in straight back syndrome therapy is directed toward specific coexisting conditions (e.g. MVP).
Although congenital absence of the pericardium and straight back syndrome seem to be unrelated, it is important to know their similarities: usually asymptomatic, basal systolic murmurs, right bundle branch block in ECG, levoposition of heart in postero-anterior chest X-ray. Furthermore we want to propose that echocardiography of the patient with straight back syndrome could have abnormal view and paradoxical septal motion probably due to clockwise rotation of heart. Not knowing these issues lead us to misdiagnose patient as congenital absence of pericardium primarily.
R.Mollazadeh, Nemazee Hospital, Shiraz, Iran E mail: firstname.lastname@example.org Tel: +98 917-313-3749 Fax: +98-711-6261089 P.O. Box: 71435-1414