Year : 2021  |  Volume : 24  |  Issue : 4  |  Page : 514--515

Describing right ventricular dysfunction: Diagnostic accuracy studies and sources of bias

Chitra Rajeswari Thangaswamy, Rajkumar Sundararaj, Satyen Parida, Ajay Kumar Jha 
 Department of Anaesthesiology and Critical Care, JIPMER, Puducherry, India

Correspondence Address:
Satyen Parida
Department of Anaesthesiology and Critical Care, JIPMER, Puducherry

How to cite this article:
Thangaswamy CR, Sundararaj R, Parida S, Jha AK. Describing right ventricular dysfunction: Diagnostic accuracy studies and sources of bias.Ann Card Anaesth 2021;24:514-515

How to cite this URL:
Thangaswamy CR, Sundararaj R, Parida S, Jha AK. Describing right ventricular dysfunction: Diagnostic accuracy studies and sources of bias. Ann Card Anaesth [serial online] 2021 [cited 2022 Jan 23 ];24:514-515
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To the Editor,

We compliment Singh et al. for their recent publication on the role of portal venous pulsatility fraction as a test to identify right ventricular (RV) dysfunction in patients undergoing cardiac surgery. However, we have the following contentions with regard to the manuscript.[1] The limitations in this study relate to spectrum or selection bias, lack of rater blinding, and limited working definition of positive and negative test results.

Firstly, this clinical study seems to suffer from spectrum or selection bias. Selection bias occurs when the patients of a study are not archetypal of the population to which the test mainly relates. If the population that is tested in a particular study embodies those patients who have a high frequency of a distinct ailment, it could result in a high feasibility that the dysfunction is present in most of those tested. For example, in the current study there is no mention of the case spread of the patients. If there were, for instance, a substantial number of mitral valve stenosis patients with a higher propensity for development of RV dysfunction, there is the feasibility that the test (portal venous pulsatility fraction) will be found positive in excess of the population that might have the ailment assessed (in this case, RV dysfunction), than that would be present for other types of cardiac surgeries. Often, spectrum bias will boost the sensitivity of a test and enhance the value of the clinical test. Thus, in the absence of reporting of the case spread, it is totally possible that spectrum bias could have influenced the findings of this study.

Secondly, the study seems to lack pertinent rater blinding. Hence, researchers may have a disposition to select a positive or negative effect based on cognizance of the ramifications of the gold standard test, other auxiliary data, past knowledge, or their own tastes. Thus, the feasibility of communicating a positive judgement for the portal venous pulsatility fraction might have been crucially changed by other constituents, such as for example, subject history, which lie beyond the results of the particular test. Thus, the validity of the particular test under consideration may again be aggrandized.

Lastly, many tests lack a pertinent threshold or cut-off score to denote either a positive or negative result. Modifying the cut-off point that dictates whether a test is positive or negative, can crucially affect the sensitivity and specificity of a test. For the study findings to be applied to clinical cases, workable elucidation of positive and negative test results on dichotomous tests need to be reproducible. The authors' findings of portal vein PF value of ≥45% indicating RV dysfunction seems to be at sharp variance with the earlier studies conducted by Shih et al. and Denault et al. that obtained cut-offs of 87.8% and 75.35%, respectively, raising questions about the fidelity of the parameter to accurately predict RV dysfunction in all clinical situations.[2],[3]

The issues outlined above indicate some latent biases accompanying the clinical special tests and their diagnostic accuracy, in this case, the portal venous pulsatility fraction, that the authors have undertaken.

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Conflicts of interest

There are no conflicts of interest.


1Singh NG, Kumar KN, Nagaraja PS, Manjunatha N. Portal venous pulsatility fraction, a novel transesophageal echocardiographic marker for right ventricular dysfunction in cardiac surgical patients. Ann Card Anaesth 2020;23:39-42.
2Shih CY, Yang SS, Hu JT, Lin CL, Lai YC, Chang CW. Portal vein pulsatility index is a more important indicator than congestion index in the clinical evaluation of right heart function. World J Gastroenterol 2006;12:768-71.
3Denault AY, Beaubien-Souligny W, Elmi-Sarabi M, Eljaiek R, El-Hamamsy I, Lamarche Y, et al. Clinical significance of portal hypertension diagnosed with bedside ultrasound after cardiac surgery. Anesth Analg 2017;124:1109-15.