How to misuse echo contrast

Primary intracardiac tumours are rare [1], there are however several entities that can mimic intracardiac tumours. These entities include for example thrombi, mediastinal masses, metastatic lesions, vegetations, hiatal hernia, or variants of normal anatomy [2–6]. Contrast echocardiography has in recent years emerged as a modality to improve the diagnostic capacity of transthoracic echocardiography (TTE) for intracardiac masses. Thrombi are predominantly avascular, most benign cardiac tumors are relatively avascular, whereas malignant tumors are predominantly vascularised [7, 8]. The vascularity of a mass, as assessed by contrast echocardiography, may therefore represent a feature that could help differentiate various conditions. We present a case where TTE, however, completely misdiagnosed what appeared as a left atrial tumour after use of transpulmonary echo contrast.

A standard TTE exam completely misdiagnosed the left atrial mass. In contrast, TEE provided a sure way to make the correct diagnosis. The TEE images from mid-esophageal view were, however, of very poor quality presumably because of the hiatal hernia.

Probably the first report of visualisation of a hiatal hernia by TTE came from Nishimura and co-workers more than 20 years ago [9]. There have been several case reports since then in the echocardiography literature [10–21], and one larger series where the echofeatures of 20 patients with large hiatal hernias were reported [22]. The present report is to our knowledge the first where intravenous injection of transpulmonary echo contrast was performed. This was in our case not helpful, on the contrary it reinforced the misdiagnosis of tumour because of what appeared to be irregular contrast uptake within the cardiac structure.

The ingestion of carbonated beverages has been shown to be a method of differentiating hiatal hernia from tumour in TTE diagnostics, where the structure goes from being echodense to an echo-free space because of the gas in the carbonated beverage [18]. This approach was recently refined by Smelley and Lang who suggested a novel cocktail containing a carbonated beverage mixed with 1.5 ml of activated Definity contrast media [19]. The use of TEE for correct diagnosis has been suggested previously [17]. In addition, Cardiac MRI has in recent years emerged as an excellent tool in diagnosing space-occupying lesions within or in the proximity of the heart [23, 24], and has the advantage over CT of not including ionizing radiation or nephrotoxic contrast media. Cardiac MRI could therefore play an important role when TTE and/or TEE are not conclusive.

Contrast echocardiography has been suggested to improve the diagnostic capacity of TTE when it comes to differentiating intracardiac masses [7, 8], the evidence for this suggestion is however quite slim. The only reasonably large study was performed by Kirkpatrick and co-workers, who in a series of 16 patients with cardiac masses investigated this hypothesis [8]. Highest pixel intensity was found in patients with malignant tumour growth, lowest in patients with thrombus, and benign tumours in the middle. The overlap in pixel intensity was rather significant. One reason why initial incorrect diagnosis was made in the present case was the illusion of the structure being vascularised, thus implying tumour, after injection of echo contrast.

The U.S. Food and Drug Administration issued on October the 10th 2007 a "black box" warning for perflutren-containing contrast agents, which caused considerable controversies within the echocardiography community [25]. This warning was later relaxed [26]. Three recent large retrospective studies have disputed the suggestion that using the current generation echo contrast would pose a hazard to the patient [26–28]. Kusnetzky and co-workers reported single-centre data on 18.671 consecutive studies and found no increased acute mortality in patients who had received a contrast agent [27]. Main et al. reported data from a multicenter registry that included 4.300.966 consecutive patients [26]. Their finding was that patients who had received echo contrast actually had a lower mortality rate compared to those who had not received contrast. Dolan et al. compared 23.659 patients from three U.S. medical centres who had received echo contrast with 5.900 controls who had not received contrast, and found no increased mortality or nonfatal myocardial infarct in patients who had received contrast [28]. These studies clearly show that using echo contrast in stable patients does not pose a significant risk. This knowledge must be weighted against the hazards of a non-diagnostic echocardiography examination, and the potential risks accompanied by alternative tests.

In conclusion, this case report highlights the mixed information that use of echo contrast may yield and the importance of TEE for accurate diagnosis.

Written informed consent was obtained from the patient for publication of this case report.