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Invisible cardiac lesion
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invisible cardiac lesion

Case from: Stephen N. Darty, Anna Lisa Crowley

Institution:  Duke University Medical Center, Durham, NC, USA

clinical presentation:

A 43 year old female with a past medical history significant for hypertension and mild rheumatoid arthritis and no known cardiac disease experienced the sudden onset of chest pain, malaise, and pre-syncope at an airport.  Paramedics were alerted and she was found to have inferior ST- segment elevations on an ECG (see figure 1). The patient was immediately taken to the nearest cardiac catheterization laboratory and was found to have no significant coronary artery lesions.  Her peak CK-MB was in the 50s and her peak Troponin was 15. A transthoracic echocardiogram demonstrated an inferior wall motion abnormality and a left ventricular ejection fraction of 35-45% (see figure). Her symptoms and inferior ST segment elevations subsequently resolved. She was diagnosed with coronary vasospasm and treated with diltiazem, carvedilol, aspirin, clopidogrel, nitroglycerin, simvastatin, and lisinopril. After discharge, she participated in cardiac rehabilitation but reported low energy and fluid retention that was managed with low-dose diuretics. 

 

She did not have recurrent chest pain until seven months after the initial discharge when she had another episode of chest pain with pre-syncope. She reported to another outside hospital.  Her ECG demonstrated inferior ST-segment elevation with Q-waves.  She emergently underwent coronary angiography and, again, had no significant coronary artery disease.  Her peak CKMB was noted to be in the 60s. She was again presumed to have coronary vasospasm and her diltiazem dose was increased. Since her 2nd hospital discharge, the patient reported no further chest pain, but endorsed low energy and edema that resolved with diuretics. She did, however, develop significant anxiety about her condition so presented to our institution for a second opinion.


 


 Fig1.

  


Fig2

 


Fig 3.

 

Fig 4.

 

A cardiac MRI was ordered to evaluate for scar burden and etiology of heart failure.  Initial functional images were performed on a 3.0 T MRI system using steady state free precession (SSFP) cine images with a 6mm slice thickness and temporal resolution <40msec (Figures 5-10).  These images demonstrated an inferior wall motion abnormality with a quantitative LVEF of 40%.


   

 Fig 5                                                                   Fig 6

 

 
Fig 6

 

Fig 7                                                                  Fig 8

 

Fig 9                                                                     Fig 10.

 

Upon completion of non-contrast SSFP functional imaging gadolinium contrast was administered and free breathing single-shot SSFP delayed enhancement images were acquired with an inversion time set high (875 msec) for intracardiac thrombus detection (per departmental protocol) in the short axis (Fig 11) and 2 chamber view (Fig 12).  These sequences demonstrated a hypointense mass on the aortic valve.

 

Fig 10.                                                            Fig 11. 

 

Post contrast, the aortic valve was again imaged with SSFP sequences.  Surprisingly the lesion noted on the SSFP DE-CMR images were not demonstrated on the SSFP cines (Figures 12-13).

 

Fig 12.                                                            Fig 13.


Free breathing single-shot null inversion time images were then performed (Fig 14-15) for detection of myocardial infarction and fibrosis. In addition to the transmural myocardial infarction (which corresponds to ECG and functional imaging) an etched lesion now appears on the aortic valve in the same region noted on high TI images acquired earlier (Fig 10-11).

 

 

 Fig 14                                                                 Fig 15.


The cardiac MRI technologist localized the lesion from the single shot techniques with a SSFP functional image (Fig 16) that is slightly off axis for the left ventricle, but purposefully dissects the lesion.  This still does not demonstrate any abnormality

 

Fig 16.


Fast Gradient Echo imaging (FGRE) imaging techniques were then used.  FGRE techniques generally are lower in signal to noise and temporal and spatial resolution, but offer a T1 weighted cine image rather than the T2/T1 weighted cine images produced by SSFP imaging. FGRE imaging nicely demonstrates a mass on the right coronary cusp of the aortic valve at the ostium of the right coronary artery (Fig 17-18).  This lesion was presumed to intermittently embolize and/or occlude the right coronary artery causing the patient’s inferior myocardial infarction.  

 

 

Fig 17.

 

Fig 18.


A differential diagnosis for the mass was thrombus, vegetation from infective endocarditis, or non-bacterial Libman-Sacks endocarditis. A white blood cell count and ESR were normal and blood cultures were negative. The diagnosis of endocarditis was excluded (both bacterial and non-bacterial). The patient was referred for surgical resection of the mass due to recurrent embolization despite anticoagulation.


Intraoperative TEE demonstrates the mass on the right coronary cusp of the aortic valve (fig 19 in long axis and fig 20 in short axis) which was subsequently resected with preservation of the native aortic valve.

 

 Fig 19.


Fig 20.

 


Surgical pathology revealed the mass to be an atypical fibroelastoma.


 

Perspective:


Primary tumors of the heart are rare and in most cases benign.  While the nature of the tumor may be benign, it’s effects on the heart can cause symptoms of right and left sided heart failure as well as myocardial infarction [1].  Papillary fibroelastomas are the third most common benign primary cardiac tumor and are often found by echocardiography alone[2].  Cardiac MRI can provide additional insight and tissue characterization in detection and characterization of primary cardiac tumors.  Utilizing additional pulse sequences that offer different T1 and T2 tissue characteristics is important in not only helping to understand the composition of masses, but also in identification.  In this case T1 weighted delayed enhancement and T1 weighted FLASH sequences were vital to discovering this mass which was not seen on SSFP T2/T1 weighted pulse sequences.  MRI is not limited by poor acoustic windows and can also be helpful in patients when the diagnosis is unclear. 

 

 

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References:



 Case prepared by Associate Editor: Stephen Darty

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