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© 2004 European Association of Cardio-Thoracic Surgery
Acquired post-pneumonectomy dextrocardia
a Division of Cardiovascular Diseases, Mayo Clinic, 13400 E. Shea Blvd., Scottsdale, AZ 85259, USA
* Corresponding author. Tel.: +1-480-301-7078; fax: +1-480-301-8018 Received March 18, 2003; received in revised form June 1, 2003; accepted July 14, 2003
We present a case of severe acquired dextrocardia following right lung resection. On MRI, there was a 180° rotation of the heart along its vertical axis with anterior positioning of the left cardiac chambers and rightward direction of the apex.
Key Words: Dextrocardia; Pneumonectomy; Cardiac MRI
Dextrocardia is the mere presence of the heart in the right chest and may occur as a consequence of anatomical changes after pneumonectomy [1–5]. Dextrocardia may be in the form of dextroposition or dextroversion. Cardiac dextroposition is defined as the presence of the heart in the right hemithorax with normal alignment of the major axis of the heart. However, in dextroversion, the cardiac apex is to the right of midline and the major axis of the heart is aligned from the left shoulder toward the right hip [6]. In severe cases following pneumonectomy, a 60–90° counter-clockwise rotation of the heart may occur [3]. In most cases, however, the orientation of the cardiac chambers remains unchanged. We present a case of dextroversion following right lung resection with a 180° rotation of the heart along its vertical axis.
A 51-year-old male, with a history of right-sided pneumonectomy for Hodgkin's lymphoma, presented with cough, shortness of breath, and palpitations. The patient had undergone a pneumonectomy 30 years ago, followed by external beam radiotherapy and chemotherapy with no further recurrence. Since then, the patient experienced intermittent episodes of bronchitis that have progressively increased in frequency and severity as well as palpitations for the last 2 years. The remaining medical history was unremarkable. He is a lifelong non-smoker and his medications were limited to Ipratropium and Salmetrol inhalers. The patient's blood pressure was 145/80 mmHg; he was tachycardic at 110 BPM and had marked jugular venous distension. Chest examination revealed absence of breath sounds on the right with dullness to percussion and diffuse rhonchi on the left. Cardiac examination demonstrated a shifted apex and no murmurs. Moderate lower extremity edema was present. A chest X-ray revealed right-sided pneumonectomy and rightward displacement of the cardiac silhouette. Pulmonary function tests showed combined obstructive and restrictive lung disease. An ECG revealed prominent R waves in V1 and V2 indicating dextroposition, with non-specific ST-T wave changes inferiorly. Magnetic resonance imaging (MRI) demonstrated dextroversion of the heart with a 180° rotation of the heart along its vertical axis (Fig. 1). The cardiac apex was directed to the right, with anterior location of the left atrium and ventricle. The right atrium was posterior and was folded around the superior vena cava due to rotation of cardiac chambers, with distension of both vena cavae (Fig. 2). The right ventricle was posterior to the left ventricle at the apex and became anterior in position towards the base. The descending aorta remained to the left of the midline.
The patient was diagnosed with severe cardiac dextroversion and rotation following pneumonectomy. Right atrial compression by the vena cavae and the displacement caused by rotation accounted for the patient's volume overload. He responded well to diuretic therapy.
This case demonstrates an extreme form of the anatomical changes that occur following pneumonectomy. Obliteration of the post pneumonectomy space depends on both reabsorption and organization of the fluid it contains. Its diameter depends on the folding of the collapsed subcostal and mediastinal pleura [1]. The collapse of pleura depends on retraction of the intercostal space, elevation of the diaphragm, and hyperexpansion of the non-operated lung. The latter is the most important and manifests as mediastinal shift, which occurs though either rotation or transfer [1]. A right to left shift, following left pneumonectomy, occurs mostly through rotation with the aortic arch arranged in the sagittal plane. After right pneumonectomy, left to right displacement occurs mostly by transfer with subsequent dextroposition of the heart and arrangement of the aortic arch in a frontal plane [1]. In case of partial resection, the mediastinum is shifted more rightward after a right lower lobectomy, than after a right upper lobectomy. Conversely, after left upper lobectomy, mediastinal shifting is greater than with left lower lobectomy [7]. After right pneumonectomy, marked rightward and posterior deviation of the mediastinum and heart occurs to the extent that they may abut the right posterolateral chest wall [2]. This condition is also associated with recurrent pulmonary infections and malacia of the major airways due to compression of the trachea and bronchi by the great vessels [3]. A 60–90° counterclockwise rotation of the heart and great vessels (standard CT scan perspective, looking cephalad from the feet) has been described, causing a coronal orientation of the aortic arch and left pulmonary artery. However, this patient had a 180° counterclockwise rotation of his heart and great vessels. Morbidity and mortality of post-pneumonectomy changes is related to age of onset and frequency of respiratory infections, which is in turn related to the degree of mediastinal shift [3]. CT scan and MRI easily diagnose mediastinal shift and rotation as well as identify airway compression [7,8]. Surgical procedures to relieve airway obstruction have been resorted to in severe cases. Fixing of the pericardium to the sternum to realign the mediastinum to the midline, division of the aortic arch with graft placement, and anterior fixation of the pulmonary artery to relieve main bronchus compression are options. However, recurrent mediastinal shift has occurred and silastic prostheses can be placed in the right mediastinum to prevent or relieve mediastinal shift. Stenting of a functionally obstructed airway may be required to relieve obstruction [3]. The patient underwent the pneumonectomy for a potentially non-fatal condition many years ago allowing for these anatomical changes to take place. There was no damage to the contralateral lung with obstructive airway disease since the patient was a non-smoker and young at the time of the surgery. It is unclear when the anatomic changes took place either immediately following surgery or at a later date. However, given the patients long standing history of insidious symptoms, it is probably a gradual process that has occurred over time. His recent presentation is rather an acute on top of a chronic event in the form of an episode of mild heart failure probably precipitated by an infectious process. He responded well to conservative management and did not require any form surgical correction despite his severe anatomical changes.
ICVTS on-line discussion Author: Dr. Prabhakara Heggunje, Interventional Cardiology Fellow, William Beaumont Hospital, Department of Cardiology, 3601 W 13 Mile Road, Royal Oak, Michigan 48073, USA Date: 01-Dec-2003 Message: This is a very interesting case which demonstrates "L-loop" with the left ventricle being anterior and to the right of the right ventricle as a result of an acquired condition. MRI findings demonstrate normal visceral situs, but ambiguous atrial situs. A previous chest X-ray showing normal cardiac position is extremely helpful in such situations. This case report is useful for invasive cardiologists to be aware of possible complex cardiac anatomy in patients who have undergone lung surgery. Author: Dr. Surjya Das, Interventional Cardiology Fellow, William Beaumont Hospital, Department of Cardiology, 3601 W 13 Mile Road, Royal Oak, Michigan 48073, USA Date: 01-Dec-2003 Message: Very interesting case with wonderful MR images. I would appreciate the authors' clarification of dextroposition and dextroversion.
The authors wish to acknowledge Carlos Moreno and Marv Ruona for the technical assistance in preparing this article. doi:10.1016/S1569-9293(03)00146-4
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Abstract
1. Introduction
