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Electrocardiography-synchronized Multi–Detector Row CT of Right Ventricular Function

Department of Ultrasound, the First Affiliated Hospital, College of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, Zhejiang Province, People's Republic of China e-mail: zezhou_song{at}126.com

Editor:

I read with great interest the article by Dr Doan and colleagues (1), in the January 2007 issue of Radiology, which confirmed that retrospective electrocardiography (ECG)-synchronized multi–detector row computed tomography (CT) facilitates detection of right ventricular (RV) dysfunction, depending on pulmonary embolus location. The methods and interpretation of the results, however, raise several concerns:

Although the pulmonary vascular obstruction index failed to demonstrate a significant survival and nonsurvival difference, it has been shown that RV dysfunction may correlate well with the obstruction index (2), and assessment of RV dysfunction may provide more insight into the pathophysiologic consequences of pulmonary embolism (PE) than into the degree of pulmonary vascular obstruction (3). That is to say, the degree of pulmonary vascular obstruction could affect RV function to some extent and it should not be ignored. In the study by Dr Doan and colleagues (1), however, the degree of pulmonary vascular obstruction was not well described. Also, was there any relation of the differences between patients with central PE and those with peripheral PE regarding the degree of pulmonary vascular obstruction? Did it have any effect on the results of the study by Dr Doan and colleagues (1)?

In this study (1), the authors stated that retrospective ECG-synchronized multi–detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location. However, PE was classified according to two levels of thrombus occlusion: central (including central, interlobar, and lobar vessels) or peripheral (including segmental and subsegmental vessels), and it has been argued that patients with central emboli face a more grave prognosis than do patients with more peripherally located clots (4). Did the detection of RV dysfunction at retrospective ECG-synchronized multi–detector row CT depend on the differences of central, interlobar, and lobar vessels or segmental and subsegmental vessels?

In the studies relevant to the report by Dr Doan and colleagues (1), the RV dimension and volume are commonly referenced to similar left ventricular (LV) measurements and are expressed as an RV/LV ratio (1,3–6). However, LV dimension and volume could be affected by many factors even if acute PE is present. Therefore, the ratio of RV dimension and volume at acute PE and the normal value of RV dimension and volume may be more important than RV/LV ratio.

	References

TOP References References

 

1. Doan H, Kroft LJ, Huisman MV, van der Geest RJ, de Roos A. Right ventricular function in patients with acute pulmonary embolism: analysis with electrocardiography-synchronized multi–detector row CT. Radiology 2007;242:78–84.[CrossRef][Medline]
2. van der Meer RW, Pattynama PM, van Strijen MJ, et al. Right ventricular dysfunction and pulmonary obstruction index at helical CT: prediction of clinical outcome during 3-month follow-up in patients with acute pulmonary embolism. Radiology 2005;235:798–803.[Abstract/Free Full Text]
3. Ghuysen A, Ghaye B, Willems V, et al. Computed tomographic pulmonary angiography and prognostic significance in patients with acute pulmonary embolism. Thorax 2005;60:956–961.[Abstract/Free Full Text]
4. Wu AS, Pezzullo JA, Cronan JJ, Hou DD, Mayo-Smith WW. CT pulmonary angiography: quantification of pulmonary embolus as a predictor of patient outcome—initial experience. Radiology 2004;230:831–835.[Abstract/Free Full Text]
5. Quiroz R, Kucher N, Schoepf UJ, et al. Right ventricular enlargement on chest computed tomography: prognostic role in acute pulmonary embolism. Circulation 2004;109:2401–2404.[Abstract/Free Full Text]
6. Schoepf UJ, Kucher N, Kipfmueller F, Quiroz R, Costello P, Goldhaber SZ. Right ventricular enlargement on chest computed tomography: a predictor of early death in acute pulmonary embolism. Circulation 2004;110:3276–3280.[Abstract/Free Full Text]

Response

Halil Doan, MD ^*, Lucia J. M. Kroft, MD ^*, Menno V. Huisman, MD , and Albert de Roos, MD ^*

^* Department of Radiology, Leiden University Medical Center, C2-S, Albinusdreef 2, 2333 ZA Leiden, the Netherlands
Department of General Internal Medicine and Endocrinology, Leiden University Medical Center, C2-S, Albinusdreef 2, 2333 ZA Leiden, the Netherlands e-mail: A.de_Roos{at}lumc.nl

We appreciate the interest of Dr Ze-Zhou Song in our publication on RV function in patients with acute PE as assessed at multi–detector row CT (1).

We agree (as discussed in our article) that RV function may provide more information on prognosis than just the obstruction index. We speculate that abnormal RV function may prove to be a sensitive tool to assess the combined effects of vascular obstruction due to PE and the hemodynamic consequences of preexisting cardiopulmonary disease.

Furthermore, we agree that the use of a standardized and validated scoring system may help to further refine the relationship between RV dysfunction and the degree of vascular obstruction due to PE. In our study, we classified the patients as those with large central emboli versus those with smaller peripheral emboli, because our primary goal was to explore the relative value of different approaches to measure RV dimensions in two patient groups with contrasting severities of vascular obstruction. Further studies are required to investigate the relationship between RV function and a standardized scoring system.

Finally, we agree that the assessment of LV function may also add to risk stratification of patients with pulmonary emboli. Multiple factors may affect LV dysfunction, including the effects of right heart failure due to PE (2). Further studies are required to demonstrate the potential of cardiac multi–detector row CT for risk stratification in patients manifesting acute PE.

	References

TOP References References

 

1. Doan H, Kroft LJ, Huisman MV, van der Geest RJ, de Roos A. Right ventricular function in patients with acute pulmonary embolism: analysis with electrocardiography-synchronized multi–detector row CT. Radiology 2007;242:78–84.[CrossRef][Medline]
2. Belenkie I, Dani R, Smith ER, Tyberg JV. Ventricular interaction during experimental acute pulmonary embolism. Circulation 1988;78:761–768.[Abstract/Free Full Text]

This Article Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Song, Z.-Z. Articles by de Roos, A. Search for Related Content PubMed PubMed Citation Articles by Song, Z.-Z. Articles by de Roos, A.