The term “cor pulmonale” is still very popular in the medical literature, but its definition varies and there is presently no consensual definition. Forty years ago an expert committee of the World Health Organization¹ defined cor pulmonale as “hypertrophy of the right ventricle resulting from diseases affecting the function and/or structure of the lungs . . .”. This pathological definition is in fact of limited value in clinical practice. It has been proposed to replace the term “hypertrophy” by “alteration in the structure and function of the right ventricle”. It has also been proposed to define clinically cor pulmonale by the presence of oedema in patients with respiratory failure. Finally, as pulmonary arterial hypertension is “the sine qua non” of cor pulmonale,² we believe that the best definition of cor pulmonale is : pulmonary arterial hypertension resulting from diseases affecting the structure and/or the function of the lungs; pulmonary arterial hypertension results in right ventricular enlargement (hypertrophy and/or dilatation) and may lead with time to right heart failure.

A new diagnostic classification of pulmonary hypertension was developed by a group of experts in 1998³ and is presented on table 1. In our opinion cor pulmonale corresponds to the third part of this classification (pulmonary hypertension associated with disorders of the respiratory system and/or hypoxaemia) and must be distinguished from pulmonary venous hypertension (part 2), and also from primary pulmonary hypertension (part 1) and from thromboembolic pulmonary hypertension (part 4).

This article reviews the current state of knowledge about pulmonary hypertension resulting from disorders of the respiratory system and/or from chronic hypoxaemia. We will only consider chronic cor pulmonale. Particular emphasis will be placed on chronic obstructive pulmonary disease (COPD) which is by far the main cause of cor pulmonale.