Norell, Michael Simon; (1990) Left ventricular performance during coronary angioplasty. Doctoral thesis (M.D), UCL (University College London).

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Abstract

Left ventricular (LV) performance during elective single vessel coronary angioplasty (PTCA) was assessed in 67 patients with intravenous digital subtraction ventriculography. Left ventriculography, following right atrial contrast injection, was well tolerated and produced images suitable for analysis in all cases. During balloon inflation, marked contractile abnormalities developed rapidly in ventricular segments subtended by the treated artery. The degree of contractile dysfunction was lessened in the presence of collateral vessels and was independent of short (20 secs) or long (60 secs) balloon inflation, and the presence or absence of additional coronary disease. During PTCA LV end-diastolic volume remained unchanged and LV end-systolic volume increased. However, ECG R wave amplitude decreased, supporting the view that during ischaemia LV volumes are independent of R wave amplitude. "Reciprocal" ECG changes were examined in patients with single vessel disease undergoing left anterior descending PTCA. Despite the development of inferior ST segment depression, inferior LV segmental contraction remained unaltered while inferobasal contraction was augmented. This confirms that these remote ECG changes did not indicate additional ischaemia but represented only an electrical phenomenon. In patients undergoing PTCA after successful thrombolysis for acute myocardial infarction, balloon occlusion was used to "reproduce" thrombotic coronary occlusion. A deterioration was apparent in global and regional LV performance during balloon inflation which may represent the extent of myocardium salvaged by thrombolytic therapy. In the 37 patients studied after PTCA, segmental contraction had returned to baseline values confirming that multiple balloon coronary occlusions of up to 60 seconds do not produce sustained abnormalities of LV contraction detectable by this method. PTCA allows a unique opportunity to examine the immediate effects of controlled coronary occlusion on LV performance. Intravenous digital subtraction ventriculography provides a valuable method with which to study these changes.

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