An Electrocardiographic and Acoustic Cardiographic Study of Acute Coronary Occlusion During Percutaneous Coronary Intervention
Doctor of Philosophy
University of California, San Francisco, 2008
Ventricular dysfunction, as measured by a rise in ventricular filling pressure or abnormal wall motion on echocardiogram, has often been observed without or prior to ST changes during ischemia. However, these conventional measurement methods for ventricular function are either invasive or not readily available at the bedside.
The overall aim of this dissertation has been to investigate whether, using acoustic cardiography, the appearance or increased intensity of diastolic heart sounds, a non-invasive measurement of ventricular function, may (a) augment the detection of ischemia when combined with ST changes and (b) occur earlier than ST changes or angina during ischemia induced by coronary occlusion during PCI.
A prospective observational study was performed with a convenience sample of 80 patients referred for non-urgent cardiac catheterization with possible PCI. Acoustic and ECG data were gathered simultaneously and continuously before and during cardiac catheterization and PCI.
Among the 80 patients, 24 patients received PCI and developed ST changes > 2 SD in ≥ 2 contiguous leads during coronary occlusion. Diastolic heart sounds occurred in all patients who met the standard ST-T wave criteria for ischemia; in two-third of patients without ST changes; and in about 90% of patients without angina during coronary occlusion. All patients who did not have diastolic heart sounds during coronary occlusion in PCI did not have ST changes that met the standard ST-T wave criteria. Our study showed that the combined use of diastolic heart sounds and ST-T wave criteria improved the sensitivity to predict myocardial ischemia by 31.6% but reduced the specificity by 22.2%. The absence of diastolic heart sounds was shown to be helpful to rule out the presence of myocardial ischemia.
Electrocardiographic ST-T changes were the earliest sign of ischemia during coronary occlusion and they were also the first to resolve after balloon deflation. Anginal symptoms were either the last event in the ischemic cascade or, in 90% of patients, did not occur during coronary occlusion. The monitoring of changes in diastolic heart sounds along with ECG monitoring at the bedside may improve the early detection of myocardial ischemia.
Barbara J. Drew, RN, FANN, PhD