Author + information
- Alberto Palazzuoli, MD, PhD∗ ( and )
- Gaetano Ruocco, MD
- ↵∗Cardiovascular Diseases Unit, Department of Internal Medicine, Hospital Le Scotte, University of Siena, Viale Bracci, Siena 53100, Italy
Although the relationship between pulmonary hypertension and right ventricular dysfunction is load dependent, the 2 parameters can have a different time course and evolution. Increased pulmonary pressure can also occur independent of pulmonary vascular resistance. Thus, there is an increased interest in determining the precise score able to detect either incremental pulmonary vascular resistance or right ventricular systolic dysfunction. Accordingly, Haddad et al. (1) proposed a diagnostic screening that includes several clinical and echocardiographic parameters. The current scoring system appears useful and easily applicable in clinical practice, but in our opinion, it does not include some important items. With regard to the right ventricular adaptations due to increased afterload, we currently recognize 2 distinct right ventricular patterns: first, an adaptive pattern consisting of concentric remodeling (a high mass-to-volume ratio), increased myocardial wall thickness, preserved systolic function, and increased filling pressure; and, second, a maladaptive pattern consisting of eccentric hypertrophy (low mass-to-volume ratio), an increase in right ventricular free wall, and concomitant systolic dysfunction (2). This aspect appears underestimated in the paper and deserves specific consideration and application in the proposed method.
The authors focused their score on echocardiographic measurements of right chambers size; unfortunately, this technique has some important limitations. Indeed, with this method, it is not possible to analyze the whole right ventricular wall, its regional abnormalities, and the right ventricular outflow tract in patients with pulmonary arterial hypertension. Measuring the tricuspid annulus plane systolic excursion is an accurate parameter for longitudinal ventricular function evaluation related to poor outcome (3); however, it does not provide precise information about the true right ventricular ejection fraction, segmental and global kinesis, and dyssynchrony between the left and right ventricular chambers. Early right heart adaptation to pulmonary hypertension considers right ventricular outflow tract and pulmonary valve morphology and dimensions; in both cases, echocardiography is not able to assess them. Although advances in echocardiographic assessment could allow an indirect evaluation of right cardiac function with right ventricular fractional area change and right ventricular myocardial performance index, these measurements are performed in 2 dimensions and have the same limitations as the physician-related point of view, patient-related acoustic window, and incomplete right heart visualization. In our opinion, a complete study of the right heart should comprise hemodynamic, functional, and structural alterations; in accord with this approach, the score should be integrated with other echocardiographic parameters: systolic pulmonary pressure and mean pulmonary pressure estimation by tricuspid and pulmonary valve in a noninvasive index screening, appears much more important than right atrial area measurement that simply reflects the severity of tricuspid regurgitation.
The score should be also extended with another diagnostic tool that provides more information about right heart structure and function such as cardiac magnetic resonance. Magnetic resonance gives more precise information about right ventricular size morphology and enlargement; furthermore, this examination is able to precisely calculate right ventricular ejection fraction and regional parietal alterations. Right heart analysis by magnetic resonance provides the physician with other important prognostic data on the dyssynchrony between the left and right ventricular chambers (4). In accord with the REVEAL registry score, both the 6-min walking test and B-type natriuretic peptide testing are predictive of mortality in pulmonary hypertension (5). The current method also excluded functional parameters such as the 6-min walking test or cardiopulmonary exercise testing, both of which demonstrated a good relationship with outcome. Finally, in our opinion, too much importance has been attributed to systemic blood pressure values that are a simply a surrogate of a reduced filling amount into left chambers size and reflects decreased output due to both left ventricular mismatch and reduced blood flow from the venous pulmonary system.
We believe that the proposed scoring needs to be extended with the above-cited pulmonary pressure measurement and magnetic resonance data, leading to a more complete evaluation of right ventricular shape, systolic function, and pressure. In our opinion, this application will be able to identify both right and left ventricular adaptation, helping physicians to decide whether to subject patients with pulmonary hypertension to a more aggressive treatment and possibly to lung transplantation before pulmonary resistance irreversibility occurs.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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