Use of monophasic action potential recordings during routine coronary-artery bypass surgery as an index of localised myocardial ischaemia

An electrogram was recorded from the angioplasty catheter guide wire when coronary blood flow was interrupted in 20 patients undergoing percutaneous transluminal coronary angioplasty. Monophasic action potentials were recorded from the right ventricular septum together with the routine electrocardiogram. The patients were studied during angioplasty for lesions in the left anterior descending (12), circumflex (3), and right coronary arteries (6). ST elevation in the electrogram recorded in the left anterior descending and circumflex systems was usually more obvious than that in the electrocardiogram. Signals obtained from the right coronary artery were of very low amplitude and registered only minimal ST changes. The ST elevation developed in the electrogram during insertion of the catheter before inflation of the balloon in 11 of the 15 patients undergoing angioplasty of the left system. In eight of the patients showing pre-inflation ST elevation the ST shift lessened after successive inflations. Monophasic action potential recordings were obtained during 45 balloon inflations in 19 patients. In those patients undergoing angioplasty for lesions of the circumflex coronary artery the monophasic action potential showed no change during balloon inflation. In patients undergoing angioplasty for the right coronary artery the mean normalised duration at 60 seconds' occlusion was 99.6 (1.5)% of control. Of a total of 25 occlusions in the patients undergoing angioplasty for the left anterior descending coronary artery 19 showed shortening of less than 5%, five showed shortening between 5 and 10%, and one showed a shortening of 16.4% in the monophasic action potential. The QT interval was satisfactorily measured in the electrogram during 36 balloon inflations, and in 24 of these it was also measured in the electrocardiogram. QT changes in the electrogram tended to be the opposite of those in the electrocardiogram. When changes in RR interval were minimal (less than 20 ms) during the balloon inflation 14 of 17 electrograms showed QT prolongation but only one of 12 electrocardiograms showed prolongation. Conversely one of 17 electrograms showed shortening compared with eight of 12 electrocardiograms. There was angiographic evidence of the development of collaterals in six of 15 patients undergoing angioplasty of the left system. ST segment elevation in both the electrogram and electrocardiogram was less pronounced in these patients than in those without evidence of the development of collaterals. ST segment changes recorded from the angioplasty guide wire provide a more sensitive index of ischaemia than the surface 12 lead electrocardiogram, and fall in ST segments on balloon deflation is a prognostic index of a good angiographic result in the left anterior descending and circumflex arteries, but not in the right coronary artery.

https://heart.bmj.com/content/heartjnl/62/5/342.full.pdf

The epicardial electrogram: a quantitative assessment during balloon angioplasty incorporating monophasic action potential recordings.

1. Effects of acute myocardial ischemia and reperfusion in conscious animals.- Instrumentation techniques for measurements of regional myocardial function in conscious animals.- Relationship between reduction in regional blood flow and myocardial function.- Adjustment to global LV ischemia.- Adjustment to regional myocardial ischemia.- Effects of reperfusion.- Enzyme leakage from ischemic myocardium.- Summary.- References.- 2. Early changes in wall thickness and epicardial wall motion during coronary angioplasty in man. Similarities with in vitro and in vivo model.- Echocardiographic changes in wall thickness.- Changes in epicardial wall motion.- Regional marker motion.- Analysis of pressure-derived indexes during systole and diastole.- Results.- Changes in regional epicardial wall motion.- Changes in global left ventricular function.- Discussion.- Early wall motion changes during acute ischemia.- Wall motion abnormalities in chronic ischemia.- References.- 3. Intracoronary electrocardiogram during transluminal coronary angioplasty.- and methods.- Results.- Discussion.- References.- 4. Clinical, electrocardiographic and hemodynamic changes during coronary angioplasty. Influence of nitroglycerine and nifedipine.- Methods.- Results.- Ischemic tolerance.- Ventricular function.- Discussion.- Summary.- References.- 5. Wall thickening and motion in transient myocardial ischemia: Similarities and discrepancies between different models of ischemia in man (Prinzmetal's angina, coronary angioplasty, Dipyridamole test).- Echocardiographic markers of ischemia.- The clinical model of transmural vasospastic ischemia and coronary angioplasty.- Evaluating the site of myocardial ischemia before coronary angioplasty: a role for the Dipyridamole-echocardiography test.- References.- 6. Effect of prolonged balloon inflations on hemodynamics and coronary flow with respect to balloon position in patients undergoing coronary angioplasty.- Methods.- Results.- Coronary sinus flow.- Coronary sinus flow and hemodynamics.- Collateral flow.- Discussion.- Flow during occlusion.- Reactive hyperemia.- Coronary sinus flow and hemodynamics.- Implications.- References.- 7. Myocardial release of hypoxanthine and lactate during coronary angioplasty: A quickly reversible phenomenon, but for how long?.- Patients and methods.- PTCA technique.- Lactate measurements.- Hypoxanthine determination.- Flow measurements.- Statistical analysis.- Results.- Coronary hemodynamic measurements.- Lactate and hypoxanthine metabolism.- Discussion.- Use of purine release as a marker for ischemia during transluminal occlusion in man.- Metabolism during reperfusion.- Summary.- References.- 8. Role of potassium in the genesis of arrhythmias during ischemia. Evidence from coronary angioplasty.- Electrolytes in the ischemic myocardium.- Calcium.- Sodium.- Hydrogen ion.- Potassium.- Shortening of the action potential during myocardial ischemia.- Changes in the plasma potassium during myocardial ischemia.- Conclusion.- References.- 9 "Collateralpressure" (occlusion pressure) during coronary angioplasty in coronary artery disease.- Methods.- Results.- The relation between the collateral pressure (OP) and the amount of visible collaterals (study 1).- The influence of Nifedipine on the collateral pressure (study 2).- The relation between the collateral pressure and the occurrence of restenosis (study 3).- Discussion.- Summary.- References.- 10. Assessment of the dynamic and functional characteristics of collateral flow observed during sudden controlled coronary artery occlusion.- Methods.- Study patients.- Cardiac catheterization and angioplasty protocol.- Study protocol.- Results.- Changes in collateral filling during coronary occlusion (Fig. 5).- Hemodynamics.- Indices of myocardial ischemia with reference to collateral flow.- Discussion.- The coronary collateral circulation is a dynamic circulation.- Can collateral circulation limit ischemia?.- Present study.- Clinical implications.- Summary.- References.- 11. Left ventricular cineangiography during coronary angioplasty.- Selection of the patients.- Left ventricular cineangiography procedure during PTCA.- Results.- Left ventricular pressures.- Left ventricular volumes and ejection fraction.- Left ventricular diastolic function.- Segmental wall motion.- Reversibility of the ischemic changes.- Comments.- References.- 12. Left ventricular filling during acute ischemia.- Methods.- Results.- Left ventricular relaxation.- Left ventricular stiffness.- Left atrial contraction.- Discussion and conclusions.- References.- 13. Ejection filling diastasis during transluminal occlusion in man. Consideration on global and regional left ventricular function..- Study population and protocol.- Methods.- Analysis of pressure derived indices during systole and diastole.- Analysis of regional and global left ventricular function.- Ejecting dynamics.- Filling dynamics.- Diastasis.- Statistical analysis.- Results.- Global left ventricular function during systole and diastole.- Regional indexes of left ventricular ejection and filling and regional pressure-radius length relations.- Regional pressure-radius length relation.- Discussion.- Myocardial ischemia, transient asynergy and altered relaxation.- Uncoordinated segmental contraction as a cause of impaired filling dynamics.- Determinants of filling dynamics.- Role of the asynchronous contraction.- Effect of coronary occlusion on left ventricular chamber stiffness and regional diastolic pressure-radius relations.- Significance of the upward shift in pressure-volume and pressure-radius relations.- Comparison with animal models of acute low-flow ischemia.- Mechanism of increased myocardial stiffness.- Conclusion: PTCA as an ischemic model?.- Early wall motion during acute ischemia: how to interpret?.- Are there clinical implications in chronic ischemia?.- Are there clinical implications for the PTCA procedure?.- References.

Coronary angioplasty : a controlled model for ischemia

Objective —To examine the incidence and severity of myocardial ischaemia provoked in the course of perfusion scintigraphy by coronary vasodilators using endocardial recordings of steady state monophasic action potentials as an independent marker of early localised myocardial ischaemia. Patients —31 men undergoing routine cardiac catheterisation for investigation of chest pain were studied. Setting —A tertiary cardiac referral centre. Design —Single site monophasic action potentials were recorded from the left or right ventricle or both (50 recording sites) during intravenous infusion of dipyridamole (0·015 mg/kg/min) for four minutes. Heart rate was held constant with atrial pacing at 20% above the patient9s resting rate. Technetium-99m hexakis-2-methoxy-2-methylpropyl-isonitrile (MIBI) was administered four minutes after dipyridamole, and single photon emission tomographic imaging was performed an hour later. Rest images were obtained the next day (two day, two dose protocol). Recordings were divided into three groups based on the scintigraphic perfusion characteristics and coronary anatomical data for the action potential recording site: group 1—recordings from areas with a normal perfusion pattern (n = 30), group 2—recordings from areas with a perfusion defect and subtended by significantly narrowed coronary arteries without obvious angiographic collateral supply (n = 10), and group 3—recordings from areas with a perfusion defect and subtended by occluded arteries with angiographically evident collaterals from adjacent vessels (n = 10). Results —There were changes in the duration of the monophasic action potential indicative of ischaemia—that is, shortening of duration of steady state action potential—in 18 of the 20 recordings from areas of abnormal perfusion. Peak changes were apparent eight minutes from the start of the dipyridamole infusion. Mean (SEM) values for duration of the action potential between control and peak effect at eight minutes were 276·5 (5·3) ms ν 276·6 (5·4) for group 1 (NS), 289·6 (4·7) ms ν 278·4 (4·9) ms for group 2 (p Conclusions —These data provide strong evidence for the presence of myocardial ischaemia in regions of reversible perfusion defects induced by dipyridamole. This study also shows that such ischaemia is more intense and more likely to be seen when myocardial viability is dependent on collateral circulation.

https://heart.bmj.com/content/heartjnl/68/7/21.full.pdf

Vasodilator myocardial perfusion imaging: demonstration of local electrophysiological changes of ischaemia.

/pdf/monophasic-action-potential-new-uses-for-an-old-technique-2eqqj9o1sj.pdf

Monophasic action potential. New uses for an old technique

The electrophysiological and mechanical events that follow transient therapeutic coronary artery balloon occlusion were analyzed in five patients. A marked (mean, 60 msec) decrease in the repolarization time of the left ventricular ischemic zone (assessed indirectly from endocardial monophasic action potential [MAP] recordings) ensued within 6 to 10 beats of occlusion. Abnormalities in left ventricular relaxation occurred almost simultaneously and preceded contraction abnormalities. A shift in the ST segment in the electrocardiogram (ECG) usually followed within the next 5 to 10 beats. An increase in heart rate (approximately 10 beats per minute) appeared last in the sequence of events. Angina was a variable parameter, frequently absent. Thus, intracavitary recordings of the electrical and mechanical changes are sensitive indicators of the early ischemic changes that follow coronary occlusion, and may be used to assess the effects of therapeutic interventions on events resulting from a myocardial perfusion deficit.

Study of electrophysiological ischemic events during coronary angioplasty.

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Study of electrophysiological ischemic events during coronary angioplasty.