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Eur J Cardiothorac Surg 2006;30:814-815
© 2006 Elsevier Science NL

Letters to the Editor

Reply to Lavi and Lavi

Clinic for Cardiovascular Surgery, University Hospital Zürich, Switzerland

Received 22 August 2006; accepted 23 August 2006.

^_* Corresponding author. Address: Clinic for Cardiovascular Surgery, University Hospital Zürich, Rämistr. 100, CH-8091 Zürich, Switzerland. Tel.: +41 1 255 11 11; fax: +41 1 255 44 46. (Email: andre.plass{at}usz.ch).

Key Words: 64-Slice computed tomography • Coronary angiography • Coronary artery disease • Cardiovascular surgeon

All comments of Lavi and Lavi [1] are very well taken and debatable.

Already mentioned in the article and also by Lavi and Lavi, the evaluation of the MSCT examination can be influenced by the radiologist who is the inter-station between the patients’ examination and the final evaluation by the cardiac surgeon. At present there is no standardized protocol of a complete examination procedure for cardiac surgeons. The radiologist is pre-selecting the images which then already tend to a certain diagnosis.

A possible improved protocol would be the presentation of MSCT images in a way that the reader can choose different images of interest which he is able to scroll through himself.

It is possible that the mixture of patients with diseased and not diseased coronary arteries can improve the accuracy of the MSCT because of the easier evaluation of healthy arteries. However, the identification of valvular disease was not a guarantee for normal coronary arteries. Eleven of the 40 patients of the study group with coronary artery disease also had valvular disease. This means that the identification of valvular disease was not equivalent with no coronary artery disease.

The 10 patients of the control group with no coronary artery disease but with valvular disease were probably easier identifiable. However, also these coronary arteries partly showed wall irregularities and calcifications.

We believe that screening for coronary artery disease with MSCT will play an important role in the future which should be taken into account for the overall accuracy.

The statement ‘There was no need to administer B blockers’ by Lavi and Lavi is not applicable for this study. Before the start of this study we discussed the application of beta blockers. Although the administration of B blocker for certain patients would have been helpful, it was decided not to add any additional medication. Also for older patients with cardiac disease, for example aortic valve disease combined with coronary artery disease, there is always a potential risk to administer additional B blockers and a medical specialist is necessary for monitoring.

Thirty-seven patients of the study group and five patients of the control group already were on B blockers before the MSCT-examination whereas four of the study group and two of the control group still had higher heart rates than 75 beats/min (bpm) during the MSCT. Overall, nine patients (six of the study group, three of the control group) had a heart rate higher then 75 bpm.

In 5 of the 11 patients with reduced image quality segments was caused at least one segment because of motion artefacts. Three of these patients had a heart rate above 75 bpm.

The 64-MSCT is using a 1-segment algorithm for MSCT examinations to a heart rate of 65 bpm. For a heart rate higher than 65 bpm, a 2-segment algorithm is used whereas to the heart rate of 75 bpm the image quality shows normally no motion artefacts. If the heart rate is higher than 75 bpm the probability for motion artefacts increases which does not mean that automatically motion artefacts will appear. Motion artefacts depend on several factors, i.e., a stable and not moving anatomical position of the heart in the chest and regular heart rate during the ECG gate examination.

It can be assumed that all cardiac surgeons are familiar with coronary angiographies. It is not only a diagnostic tool, but also necessary for the preoperative planning of a CABG.

There was no specific training for the readers. However, both surgeons were already familiar with examinations and evaluations of the 16-MSCT which was necessary for a previous study. However, what criteria should apply for an experienced examiner can be discussed. Also a defined training for MSCT examination for cardiac surgeons as well as for cardiologists should be discussed seriously.

Lavi and Lavi also mentioned additional data which can be collected by a cardiac CT and would be valuable for cardiovascular surgeons.

Indeed, we already elaborated on this matter in the discussion part of this publication [2]. Especially the possibility to diagnose valve pathologies including the identification and quantification of calcifications and morphologic abnormalities are very useful [3]. Additionally, preoperative planning with MSCT for minimally invasive surgeries will be of increased importance in the future [4]. The value for preoperative planning for redo surgeries has already been described in several papers [5].

References

1. Lavi R, Lavi S. Coronary artery imaging with 64-slice computed tomography from cardiac surgical perspective (letter to the editor (LTTE)). Eur J Cardiothorac Surg 2006;30:813-814.[Free Full Text]
2. Plass A, Grunenfelder J, Leschka S, Alkadhi H, Eberli FR, Wildermuth S, Zund G, Genoni M. Coronary artery imaging with 64-slice computed tomography from cardiac surgical perspective. Eur J Cardiothorac Surg 2006;30:109-116.[Abstract/Free Full Text]
3. Gilkeson RC, Markowitz A, Sachs P. Evaluation of the cardiac surgery patient with MSCT. J Thorac Imaging 2005;20(4):265-272.[CrossRef][Medline]
4. Herzog C, Wimmer-Greinecker G, Schwarz W, Dogan S, Moritz A, Fichtlscherer S, Vogl TJ. Progress in CT imaging for the Cardiac surgeon. Semin Thorac Cardiovasc Surg 2004;16(3):242-245.[Medline]
5. Aviram G, Sharony R, Kramer A, Nesher N, Loberman D, ben-Gal Y, Graif M, Uretzky G, Mohr R. Modification of surgical planning based on cardiac multidetector computed tomography in reoperative heart surgery. Ann Thorac Surg 2005;79(2):589-595.[Abstract/Free Full Text]

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