I. Effects of chronic chest disease on right heart structure and function In patients with restrictive lung disease, right ventricular hypertrophy was estimated to be present in 50% of them (Figure15) (Shivkumaret al., 1994). Despite these changes in the structure of the right ventricle, myocardial systolic function is generally conserved in pulmonary hypertension associated with chronic lung disease (Vizza et al., 1998). Concentric RV hypertrophy can predate resting hypoxia in patients with stable COPD (Vonk-Noordegraaf et al., 2005). The normally thin-walled compliant RV is hypertrophied to moderate the rising intraluminal pressure and ultimately decreases wall stress. Increased RV thickness is …show more content…
Effects of chronic chest disease on cardiac mechanics Chronic chest disease may affect right and left ventricular function by changing intrathoracic pressure. Lung hyperinflation may increase RA pressure and subsequent reduction in venous return and RV pre-load (Fessler, 1997). In COPD patients, hyperinflation has been directly correlated with reduced atrial chamber size, global right ventricular dysfunction, and reduced left ventricular filling (Watz et al., 2010). Alveolar hypoxia is a strong stimulus for pulmonary vasoconstriction. It operates at the endothelial level and is one of the most important pathways leading to development of PH in chronic lung diseases. Alveolar hypoventilation precipitates acute pulmonary vasoconstriction in some regions of the lungs and vasodilatation in others, causing physiological shunt. Hypoxia causes pulmonary vasoconstriction leading to an increase in PVR. Two mechanisms are hypothesized to underpin this phenomenon. Vasoconstriction is achieved either through activation of a vasoconstrictor pathway or inactivation of a vasodilator pathway, or alternatively via the effects of hypoxia on the vascular smooth muscle (Sylvester et al.,