Cardiac Arrhythmias and Left Ventricular Function in Respiratory Failure from COPD: Discussion (Part 2)
Actually PFR, which is the only predictive variable in our model for VPC, is inversely related to the arrhythmia score (Table 6). A mild left ventricular diastolic dysfunction could thus be a hallmark of COPD patients at risk for VPC. This dysfunction can be attributed to silent myocardial ischemia or to left ventricular dependence from a right ventricle that is overloaded. The latter hypothesis has not been investigated, at present, because equilibrium-gated radionuclide angiocardiography is not very well suited to assess right ventricular performance. The former hypothesis is connected to the definition of the ar-rhythmogenic role of hypoxia in a minority of COPD patients. It is likely that hypoxia, directly or by increasing the sympathetic activity, affects the performance of the left ventricle and increases the risk of VPC in patients affected by RF and a coexisting coronary disease. Eventually, aging itself might account for some impairment of the left ventricular diastolic relaxation. The sensitivity of the ventricular relaxation to so many factors makes PFR an early indicator of diastolic dysfunction in the presence of normal or near normal LVEF in both coronary artery disease and RF. This might account for the superiority of PFR upon LVEF as a prediction of ventricular arrhythmias in the present study. ventolin inhaler
Our results confirm that the left ventricular systolic function, as reflected by LVEF and PER, usually is normal in COPD patients. This finding is particularly interesting, as most previous observations were carried out on younger people with shorter histories of COPD. Our data suggest that left ventricular ejection phase indices are fairly normal regardless of the duration of COPD.