Pseudo Heart Disease: 1/5 Norman Bethune Faculty of Medicine, Jilin University, China

Transcription

1 Pseudo Heart Disease: 1/5 Case 060: Pseudo Heart Disease Author: Affiliation: Zhang Shu Norman Bethune Faculty of Medicine, Jilin University, China A 17 year-old girl presented to the Clinic because of sudden blackouts. The loss of consciousness was transient and happened twice recently: Once after going to the toilet passing urine 6 o clock in the morning and another after a 3-hour train ride standing up. Each episode lasted 2 3 minutes and accompanied by nausea, perspiration, and pallor but not by incontinence or convulsion. These symptoms disappeared with rest. The patient recalled palpitation, chest discomfort and shortness of breath after exercise since more than 10 years ago. Last year, she had a similar blackout after an exhaustive physical education lesson. She went to a local hospital several times because of these episodes but no abnormalities were found on examination and no treatment was given. Otherwise she had no other complaints and experienced no limitations to activities of daily living. Her menstrual history was normal; she was not on any long-term medication; had no allergy; and both her parents and grand parents were alive and well. Physical examination revealed an adolescent girl looking her age. Her cheeks were rosy and the mucous membrane on the inner aspect of her eyelids was pink. Body temperature was 36.5, BP 90/60mmHg, pulse rate 76/min, respiration 16/min. She was bright, alert, and in good spirit. It was noticed that her thorax was flattened in the anterior-posterior dimension but her lungs were clear to auscultation. Heart size was normal by percussion and heart rate was 76/min and regular. A grade 2/6 systolic murmur was heard over the 2 nd and 3 rd interspace along the left sternal border. No other abnormal signs were present. 1. What are the possible diagnoses? This teenage girl gave a typical history of syncope. From her history and physical findings the more likely causes of her attacks include Micturition syncope: a vasovagal phenomenon. Orthostatic hypotension: from prolonged standing and, less likely, from hypovolemia and dysautonomia. Cardiac outflow obstruction: from aortic stenosis and possibly from hypertrophic cardiomyopathy. Hypoglycemia.

2 Pseudo Heart Disease: 2/5 Epilepsy. Other less likely but still important possibilities include: Arrhythmias. Hypersensitive carotid sinus. Massive pulmonary embolism. Intracranial space occupying lesion. Hysteria. Progress of the Case Investigations were ordered and results of CBC, urinalysis, myocardial enzyme markers, ECG, cranial CT, EEG, and pulmonary function tests were normal. Echocardiography showed widened main pulmonary artery, and mild tricuspid and pulmonary regurgitation. Her chest X-rays appear below: 2. What are the abnormalities seen in these chest x-rays? In the PA film the cardiothoracic ratio is 0.58 (upper limit of normal is 0.5), suggesting cardiomegaly. The heart looked flattened with a prominent main pulmonary artery. There is a slight scoliosis of the thoracic spine. In the lateral film the most striking feature is loss of normal dorsal curvature of the thoracic spine and obliteration of the retrosternal and retro-cardiac spaces. The anteroposterior diameter of the thorax is markedly decreased such that the ratio of the anteroposterior to lateral diameter of the thorax is only 0.32.

3 Pseudo Heart Disease: 3/5 3. What is the most likely diagnosis in this patient? The patient s presentation and her chest X-ray are consistent with a diagnosis of Straight Back Syndrome. 4. What is the Straight Back Syndrome? The Straight Back Syndrome (SBS) is a developmental abnormality in which there is loss of normal kyphotic curvature of the thoracic spine. The thoracic vertebral column is straight and a degree of pectus excavatum may be found in some patients. As a consequence the anteroposterior diameter of the thorax becomes narrower and the heart and great vessels are squashed and shifted leftward. Many of these patients were referred for cardiological assessment because of heart murmurs and subsequently found to have no organic heart disease. That is why the syndrome was called pseudo-heart disease when first reported. Subsequent investigations do find a significant number of patients with SBS have mitral valve prolapse. The cause of the disease is unknown; an autosomal dominant pattern of inheritance with incomplete penetrance has been suggested. 5. What are the clinical features of SBS? History Most common complaints are palpitation, non-cardiac chest pain, and dyspnea following exertion. These symptoms can occur either alone or in combination. Syncope is less common. Some patients are asymptomatic. Often referred by other physicians for consultation because of heart murmurs, clicks, and x-ray signs of cardiomegaly. Mostly seen in young adults; symptoms may first appear between teenage and middle-age. Family history may be positive. Physical signs Lean and lanky in body habitus. Loss of thoracic kyphosis, straightness of thoracic spine, and decrease in anteroposterior diameter of thorax when inspected from the side. Pectus excavatum or thoracic lordosis may be present.

4 Pseudo Heart Disease: 4/5 Left parasternal pulsations are visible and palpable, particularly during expiration, in some patients. Low grade systolic murmurs and non-ejection clicks are common but not systolic thrill. Laboratory investigations ECG abnormalities are non-specific if present. Chest x-ray often shows leftward shift of the heart and pseudo-cardiomegaly with prominent pulmonary artery in the PA view. Lateral view confirms straightness of thoracic spine and decrease in anteroposterior diameter of the thorax, which can be defined as a ratio of anteroposterior to transverse diameter of less than 0.35 in Chinese men and less than 0.36 in Chinese women). (The anteroposterior diameter of the thorax is measured on the lateral radiograph from the posterior border of the sternum perpendicular to the anterior surface of the 8 th thoracic vertebral body; the transverse diameter is measured at the level of the diaphragms of the PA chest x-ray.) Echocardiogram can be normal but mitral valve prolapse is found in more than 50% of patients. Pulmonary function test is normal in most instances but mild restrictive function may be found in some. Tracheal compression has also been reported in a small number of patients. 6. What is the treatment of SBS? Treatment depends entirely on the severity of presenting complaints and must be individualized. For patients with only mild symptoms that do not interfere with daily activity, a watchful approach is appropriate, particularly in juvenile subjects. Moderate increases in physical training to improve exercise capacity may be all that is needed to alleviate symptoms. The anteroposterior thoracic diameter of pubertal teenagers may improve as they grow older. If the symptoms are incapacitating however, surgical correction of underlying skeletal abnormalities may be contemplated. The type of surgery requires expert assessment of the underlying deformity and may include sternoplasty, sternal division, correction of pectus excavatum, or other decompressive procedures. Further Readings Grillo HC et al. Tracheal compression caused by straight back syndrome, chest wall

5 Pseudo Heart Disease: 5/5 deformity, and anterior spinal displacement: Techniques for relief. Annals of Thoracic Surgeons 2005;80: Cai Hongbin. Two Cases of Straight Back Syndrome. Journal of Chinese Modern Medicine 2005;10: Chen WW et al. Familial occurrence of mitral valve prolapse: Is this related to the straight back syndrome? British Heart Journal 1983;50: Davies MK et al. The straight back syndrome. Quarterly Journal of Medicine 1980;49: De Leon AC Jr. et al. The Straight back syndrome: Clinical cardiovascular manifestations. Circulation 1965;32: Rawlings MS. The straight back syndrome: A new heart disease. Disease of the Chest 1961;39: