Dual Source CT after Left Main Coronary Artery Stenting in a Patient with Arrhythmias

Stephan Achenbach, MD1 ; Ulrike Ropers, MD1 ; Dieter Ropers, MD1; Katharina Anders, MD2; Axel Küttner, MD2; Willi Kalender, PhD3; Werner Bautz, MD2; Werner G. Daniel, MD1
 |  2006-11-16

1Department of Internal Medicine 2 (Cardiology), University of Erlangen-Nuremberg, Erlangen, Germany
2Institute for Diagnostic Radiology, University of Erlangen-Nuremberg, Erlangen, Germany
3Institute for Medical Physics, University of Erlangen-Nuremberg, Erlangen, Germany


History

A 63 year old male patient with known chronic occlusion of the left anterior descending coronary artery and previous bypass surgery (internal mammary artery graft to left anterior descending coronary artery 15 years previously) experienced an acute coronary syndrome (non-ST elevation myocardial infarction). A high grade stenosis of the left main coronary artery was found. Percutaneous coronary intervention (PCI) and stent placement (Taxus® 5.0/12 mm) of the left main coronary artery was performed to restore blood flow to the left circumflex coronary artery and an intermedi- [ 1A ] Angiography of the right coronary artery (arrow). ate branch [Fig. 1]. The left internal mammary artery bypass graft and right coronary artery were found patent at the time of angiography and left main intervention. Several days after stent placement, the patient experienced non-typical chest pain at rest and a Dual Source CT scan was performed to investigate stent patency. During the DSCT scan, the patient developed arrhythmias (supraventricular ectopic beats). Image reconstruction was performed in systole (300 ms after R-wave), and half-scan reconstruction (heart rate independent 83 ms temporal resolution) was used.

Diagnosis

In the systolic reconstructions, the heart, coronary arteries, and the bypass graft were visualized free of motion artifacts [Fig. 3-5], in spite of the presence of arrhythmias throughout data acquisition. The left main coronary artery stent was depicted in axial and frontal multiplanar reconstructions and could clearly be demonstrated to be free of acute thrombotic occlusion or restenosis [Fig. 3]. In addition, reconstructions of the arterial bypass graft and of the right coronary artery showed both vessels free of significant stenosis. Diffuse disease had remained in the left circumflex coronary artery after the percutaneous intervention, and these stenoses were also demonstrated by DSCT, without change to the angiographic finding [Fig. 4 and 5]. Thus, a repeat invasive coronary angiogram was not necessary.


Comments

In spite of arrhythmias during scanning, Dual Source CT was able to rule out the presence of in-stent narrowing or occlusion of the newly implanted left main coronary artery stent. In addition, patency of the internal mammary artery bypass graft and absence of new stenosis in the right coronary artery could be demonstrated.
 

Fig. 3: Reconstruction of the left main coronary artery stent in a frontal (Fig. 3A) and axial plane (Fig. 3B) and in a curved multiplanar reconstruction that shows the stent and the left circumflex coronary artery (Fig. 3C); (large arrow: patent stent, small arrows: diffuse disease in left circumflex coronary artery, compare to Fig. 1D).

Fig. 4: Curved multiplanar reconstruction of the right coronary artery (Fig. 4A) (arrow, no significant stenosis) and of the left main and left anterior descending coronary artery (Fig. 4B) (known to be occluded; arrows =LAD, arrowhead =distal segment of IMA bypass graft and anastmosis to LAD).

Fig. 5A, 5B: 3-dimensional reconstruction of the heart and coronary arteries. The patent internal mammary artery graft to the left anterior descending coronary artery can clearly be appreciated.

Examination Protocol

Scanner SOMATOM Definition Dual Source CT
Scan area Aortic arch to diaphragm
Scan length 137 mm
Scan direction cranio-caudal
Heart rate highly irregular between 48 and 90 bpm
kV 120 kV
Effective mAs 380 mAs/rot.
Temporal Resolution 83 ms
Rotation time 330 ms
Slice collimation 2x64x0.6 mm
Slice width 0.6 mm
Pitch 0.22
Reconstruction increment 0.3 mm
Kernel B26f
Contrast 370 mg iodine/ml (Ultravist, Schering AG)
Volume 65 ml
Flow rate 5 ml / s
Start delay 23 sec