Persistent left superior vena cava
Gh. Cerin, C Coman, V. Montericcio, C. Santambrogio, P. Cioffi.
San Donato Hospital,“E Malan” Cardiovascular Center University of Milan, Italy. |
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Case report Summary
This case illustrate the echocardiographic diagnosis of persistent left superior vena cava in an asymptomatic 36 year old man who underwent a routine exam for a physical fitness programme.
Pitfalls and limitations of colour and pulsed Doppler are also discussed.
Patient history prior to current observation :A 36 year old male was attended our Echo Lab for a routine exam necessary for a physical fitness programme. He was completely asymptomatic and clinical examination including cardiovascular system, together with ECG and the chest X-rays were normal.
Transthoracic M mode measurements (fig. 1) showed normal dimensions of the cavities.
Clinical findings on admission, evolution and outcome :Parasternal long axis and apical 3 chamber view (fig. 2 showed the presence of an abnormal tubular structure, with a diameter of approximately 18 mm, situated behind the posterior mitral leaflet, apparently within the left atrium.
The colour Doppler study showed the presence of a low velocity flow inside it. An intra venous (IV) contrast study with saline bubbles demonstrated opacification of the tubular structure, and subsequent filling of the right ventricle (fig. 3).
The echocardiographic study was considered very suggestive for the diagnosis of a congenital systemic venous anomaly; in particular for the persistence of left superior vena cava.
A TOE study was then done in order to get a clearer anatomical picture and precise the place of opening of this tubular structure into the right heart.
The TOE exam in 4 chamber view (fig. 4) confirmed the presence of a vascular structure situated outside the lateral left atrial wall and superior aspect of the left atrial appendage.
Colour Doppler and PW studies demonstrated the presence of a venous flow pattern in the vascular structure. A contrast study (fig. 5) demonstrated the filling of the venous structure, the connection of this with the coronary sinus and opening of it into the right atrium.
The echocardiographic diagnosis suggested by these findings was of persistent left superior vena cava.
The TOE echo exam was then continued with a study of the aorta. Surprisingly the TOE showed a double vascular structure at the level of descending aorta, that on CD and PW study demonstrated the presence of an arterial flow pattern (fig. 6).
This led to angiographic studies being done to clarify these contradictory echo data.
Angiography (fig. 7) confirmed the presence of only one vena cava, which was left sided, and opened into the right atrium. The aorta (fig. 8) was normal.
Discussion & Conclusions :This case is interesting for two reasons. Firstly the fortuitous diagnosis of a case of persistent left superior vena cava by echo and secondly the pitfalls and limitations of colour and pulsed Doppler, which in this case gave poor spatial resolution. The arterial flow present in the aorta, having a higher velocity than the flow in the left vena cava, acted from the physical point of view, as an obstacle, abolishing recording of the low velocity flow present in the vena cava. This is not the first time that we have seen this phenomenon in our laboratory, where there is a high velocity flow, a low velocity flow and a short distance from the TOE probe and the target. Such situations can generate confusion and need careful analysis and interpretation of the data.
Persistence of the left superior vena cava (SVC) is the most common thoracic venous anomaly. It is a persistent remnant of a vessel that is present as a counterpart of normal right-sided SVC in early embryological development but normally disappears. It occurs in 2-5% of all congenital cardiac abnormalities. The diagnosis is often missed if the lesion is not looked for carefully. Drainage into the coronary sinus is well tolerated, whereas drainage into the left atrium produces a right to left shunt and may be associated with brain abscesses and/or embolisation secondary to intravenous therapy administered via the left arm (1,2). A persistent left SVC can interfere with normal development of the left ventricle and is strongly associated with obstruction to left ventricular inflow and outflow tracts (2).
A pulmonary artery catheter passed through the persistent left SVC, after being inserted into the left subclavian or jugular vein, gives a characteristic, diagnostic, X-ray picture. Even so this can be missed if the catheter goes into the normal (right) SVC. The diagnosis can be confirmed by many non-invasive tests, or it may be diagnosed incidentally at thoracic surgery or autopsy. However echocardiography is the method of choice in the diagnosis of persistent left SVC because it can be used at the patient’s bedside and allows easy detection of the drainage site. When there is no associated congenital cardiac anomality, persistent left SVC it is usually asymptomatic and haemodynamically insignificant. In our laboratory we have seen 5 patients with this venous abnormality on echo, and all of them were asymptomatic (3).
However persistence of left superior vena cava has important clinical implications in certain situations (4):
1. Implantation of transvenous pacemaker.
2. Placement of pulmonary artery catheter for intra-operative or intensive care unit monitoring without fluoroscopy.
3. Systemic venous cannulation for extracorporeal membrane oxygenation.
4. Systemic venous cannulation for cardiopulmonary by-pass.
5. Partial or total cavo-pulmonary anastomoses
6. Orthotopic heart transplantation and endomyocardial biopsies.
References :1. Voci P, Lizi G, Agati L Diagnosis of left superior vena cava by multiplane transoesophageal echocardiography. Cardiologia 1995, apr, 40(4):273- 5.
2. Agnoleti G, Annechiono F, Preda L, Borghi A.
Persistence of left superior vena caval vein: can it potentiate obstructive lesions of the left ventricle? Cardiol Young 1999, may, 9(3): 285-90
3. Sarodia BD, Stoller JK, Persitence left superior vena cava: case report and literature review. Respir Care 2000, Apr 45(4):411-6.
4. Bartram U, Van Praagh S, Levine JC, Hines M, Bensky AS, Van Praagh R. Absent right superior vena cava in visceroatrial situs solitus. Am J Cardiol. 1997,Jul 80 (2):175-83. |
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