Online detection of myocardial ischemia by near infrared spectroscopy with a fiberoptic catheter.

BACKGROUND: The interruption of myocardial O2-supply in acute myocardial ischemia causes differences in coronary venous O2-content. In this study, the oxygenation status of coronary sinus blood is detected in myocardial ischemia by near infrared (NIR) spectroscopy. METHOD: For the intravascular application, a new fiberoptic catheter is developed. After calibration of the catheter by perfusion of blood with standardized gas mixtures in an in vitro experiment, the in vivo application was performed in 12 domestic pigs. The catheter was placed into coronary sinus and an anterior ischemia was induced by temporary occlusion of LAD. NIR graphs and hemodynamic data were obtained for 90 min ischemia and 90 min reperfusion time. RESULTS: Main NIR-spectroscopic differences between oxygenated and de-oxygenated hemoglobin took place in O2-concentrations less than 30%. Coronary sinus NIR spectra of hemoglobin-oxygen binding showed significant, reproducible differences between pre-ischemia, LAD-occlusion and reperfusion. NIR graphs also show variations related to CO2-concentration, pH and temperature. CONCLUSION: The intravascular application of NIR spectroscopy could be a reliable tool in detection and follow-up of acute myocardial ischemia and infarction.     

Detection of left ventricular regional myocardial ischaemia in dogs by intraventricular conductance catheter

Nine adult mongrel dogs were instrumented with ultrasonic microcrystals to measure left ventricular basal anteroposterior diameter and midwall myocardial segment length near the cardiac apex. Pneumatic cuff occluders were positioned around the left circumflex coronary artery near its origin and around the left anterior descending coronary artery two thirds of the way along its length. A pressure microtransducer was implanted into the left ventricle. Ten days after instrumentation the animals were anaesthetised with morphine chlorhydrate and pentobarbital sodium. An eight electrode catheter was advanced into the left ventricle to measure ventricular apical and basal regional and total electrical conductance. Minor ischaemia caused by occlusion of the left anterior descending artery was detected only by the electrode pair located near the apex, as decreased local ejection fraction. Major ischaemia caused by left circumflex artery occlusion was detected by both apical and basal electrode pairs and by total conductance, the three conductance signals indicating reduced ejection fractions compared with control values. The basal diameter signal indicated that basal regional motility changed only during major ischaemia, thus confirming the specificity of the changes in the basal conductance signals. The apical segment length signal confirmed the altered motility indicated by the apical conductance signal. These results suggest that regional wall motion abnormalities may be detected by the use of a multielectrode conductance catheter.     

Intracoronary administration of saralasin: effects on cardiac arrhythmias induced by ischaemia and reperfusion in the anaesthetised dog.

OBJECTIVE: The aim was to study (1) the effects of intracoronary saralasin, an angiotensin II receptor antagonist, on ischaemia induced and reperfusion induced regional cardiac noradrenaline release and ventricular arrhythmias; and (2) the implication of angiotensin II in coronary constriction during myocardial ischaemia. METHODS: Eighteen adult mongrel dogs, weight 22.6(SD 1.1) kg, anaesthetised with sodium pentobarbitone, were used for the study. The left anterior descending coronary artery was ligated for 60 min and then reperfused for 30 min. Saralasin (60 micrograms.kg-1, n = 9) or its vehicle (Ringer lactate, n = 9) was injected into the artery at the beginning of the occlusion period. Two epicardial veins, one running parallel to the left anterior descending coronary artery and the other parallel to the circumflex coronary artery, were cannulated for the measurement of their respective blood flows and of noradrenaline, lactate, and creatine kinase release. RESULTS: Saralasin decreased the incidence of ventricular fibrillation during coronary occlusion (from 44% in the vehicle treated group to 0% in the saralasin treated group, p = 0.0412). This effect was accompanied by significant vasodilatation in both epicardial veins during myocardial ischaemia. Neither the increases in noradrenaline, lactate, and creatine kinase release nor the incidence and duration of the ventricular arrhythmias following reperfusion were modified by the administration of saralasin. CONCLUSIONS: Intracoronary saralasin in the early phase of myocardial ischaemia increases the epicardial venous blood flow significantly, suggesting that angiotensin II is implicated in coronary constriction during ischaemia. This haemodynamic effect is accompanied by a significant decrease in the incidence of ventricular fibrillation. However, the renin-angiotensin system does not appear to be implicated in the reperfusion induced noradrenaline release nor in the incidence of the ventricular arrhythmias.     

Coronary sinus potassium concentration recorded during coronary angioplasty.

Coronary sinus potassium concentration was measured continuously in two patients undergoing angioplasty of a significant stenosis of the left anterior descending coronary artery. After each coronary occlusion there was a transient rise in coronary sinus plasma potassium concentration caused by washout of potassium which had accumulated in the extracellular fluid during the short period of ischaemia. There were no significant changes in the surface electrocardiogram and the patients experienced no chest pain. Changes in coronary sinus potassium concentration provide a sensitive and early indication of myocardial ischaemia in man.     

Intermittent coronary sinus occlusion after coronary arterial ligation results in venous retroperfusion

Coronary sinus occlusion retards necrosis of ischemic myocardium. To test the hypothesis that coronary sinus occlusion induces retrograde venoarterial flow, the coronary arteriovenous pressure gradient and the coronary arterial oxygen saturation were measured distal to a left anterior descending coronary artery ligature in dogs. In parallel, we constructed a mathematical model of known coronary physiology to characterize pressure and flow patterns during coronary sinus occlusion. In dogs, coronary sinus occlusion produced a systolic pressure gradient between the coronary artery and the coronary sinus of -20 +/- 9 mm Hg (higher venous pressure, p less than 0.0001) and a positive diastolic gradient of 3 +/- 5 mm Hg (lower venous pressure p less than 0.01). An average reduction in the oxygen saturation in the ligated coronary artery of 20 +/- 13% was also observed (p less than 0.005) consequent to admixture of venous (desaturated) blood. By graded inflation of the coronary sinus balloon, it was demonstrated that desaturation of arterial blood typically occurs above a coronary sinus systolic pressure of 40-50 mm Hg. The mathematical model indicates the possibility of venoarterial pressure gradients and reversal of flow at the microcirculatory level during coronary sinus occlusion. These studies provide evidence that retrograde flow into the ischemic zone occurs in association with intermittent coronary sinus occlusion. Thus, alternating flow over the ischemic territory may be the mechanism of myocardial salvage during intermittent coronary sinus occlusion.     

The effects of myocardial perfusion with perfluorochemical substances

The effects of coronary arterial perfusion with a perfluorochemical substance (perfluorotributylamine) on the segmental myocardium of the beating heart were studied in 12 open chest anesthetized dogs. Following 10 min of left anterior descending coronary artery occlusion, perfusion of the coronary artery with the perfluorochemical returned myocardial function and metabolism toward control states, although myocardial diastolic properties as well as coronary venous PCO2 and lactate were not restored completely within 7 min after reperfusion. Perfluorochemicals may be of clinical importance in protecting the ischemic myocardium because of their oxygen carrying capacity together with favorable physiochemical properties for protection of the microcirculation.     

Vascular anomaly - left anterior descending artery originating from right coronary sinus

A case of a patient with congenital anomaly of coronary blood vessels with left anterior descending artery starting from right coronary sinus is presented. The patient was operated on due to symptoms of myocardial ischaemia by carrying out an off-pump coronary artery bypass graft to left anterior descending artery and obtuse marginal artery, with a very good outcome.     

Tissue and coronary venous pH in ischemic canine myocardium

Summary: The relationship between changes in myo-cardial tissue pH and local coronary venous pH during and after transient occlusion of the left anterior descending artery was investigated in 6 open chested an-esthesized dogs. Tissue pH was recorded with a needle pH electrode, and coronary venous pH with a specially designed catheter tip pH electrode. Myocardial tissue pH fell steadily after coronary occlusion, and had fallen by 0.107±0.043 pH units (mean±SD, n=12 occlusions) after 150 s. On reperfusion there was a further small fall in tissue pH to 0.138±0.035 units before tissue pH returned to control. In contrast, the fall of coronary venous pH during ischemia was small (0.15±0.027 after 150 s, n=12 occlusions). Within 5 s of reperfusion, a large fall in venous pH occurred, reaching a maximum of 0.150±0.072 at 20–30 s after reperfusion. During ischemia changes in tissue pH are poorly represented by changes in coronary venous pH. The size of the early change of venous pH during the reperfusion washout of retained metabolites is a better estimate of the fall of tissue pH. Measurement of metabolites in the coronary sinus of man during the washout after the end of an ischemic intervention such as atrial pacing is superior to measurements performed during pacing in providing biochemical evidence of myocardial ischemia.     

Neutrophil depletion does not prevent myocardial dysfunction after brief coronary occlusion

Recent evidence suggests that oxygen free radicals generated during ischemia or reperfusion may contribute to myocardial dysfunction after brief coronary occlusion ("myocardial stunning"). Because neutrophil leukocytes represent a potential source of oxygen radicals, the concept of whether depletion of neutrophils could attenuate myocardial stunning after 10 min of ischemia was examined. In 16 anesthetized dogs, the left anterior descending coronary artery was perfused by an extracorporeal circuit, either with (n = 8) or without (n = 8) neutrophil filters in the perfusion line. The group with filters had near total absence of neutrophils in blood perfusing the left anterior descending coronary artery territory (16 +/- 8 versus 1,826 +/- 399/microliters in the control group). Systolic myocardial shortening and end-systolic pressure-segment length relations were recorded during rest conditions and during incremental intracoronary infusion of dobutamine (5 to 15 micrograms/min) before and after 10 min of coronary flow occlusion. Before coronary occlusion, systolic myocardial shortening at rest was similar in control (15.4 +/- 1.7%) and neutropenic (12.4 +/- 2.2%) groups. Dobutamine (15 micrograms/min) resulted in increased shortening in both control (18.2 +/- 1.4%, p less than 0.01) and neutropenic (15.8 +/- 1.5%, p less than 0.05) groups and in a leftward shift of the end-systolic pressure-length relation. During coronary occlusion, collateral coronary flow to the left anterior descending coronary artery territory was not significantly different in the control (0.10 +/- 0.03 ml/min per g) and neutropenic (0.18 +/- 0.06 ml/min per g) groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Selective ECG synchronised suction and retroinfusion of coronary veins: first results of studies in acute myocardial ischaemia in dogs

STUDY OBJECTIVE--The aim of the study was to test an intermittent ECG synchronised suction device which was added to a coronary vein retroinfusion system (selective suction and retroinfusion = SSR) in order to transport oxygenated fluid more efficiently into ischaemic myocardium. DESIGN--The suction period preceding the retrograde pumping period was sufficient to allow the coronary veins to empty upstream of the retroinfusion catheter tip, thus facilitating the refilling of the veins by the retrogradely pumped oxygenated fluid. Subepicardial oxygen partial pressure measurements and determination of post mortem infarct size were used to study the efficacy of SSR treatment in an open chest infarct model. SUBJECTS--15 beagle dogs were subjected to occlusion of the left anterior descending coronary artery for up to 5 h. MEASUREMENTS AND MAIN RESULTS--Using oxygenated Ringer lactate solution for SSR treatment (given 30 min to 5 h after occlusion of the left anterior descending artery), mean subepicardial PO2 in the ischaemic myocardium of SSR treated dogs increased by 7-12 mm Hg. Mean infarct size was reduced to 5.6(SD 3)% of left ventricle in SSR treated dogs (n = 4) compared to 27(14)% in controls (n = 4). Expressed as percent of volume at risk, mean infarct size was reduced by 84% in SSR treated dogs. CONCLUSIONS--These data suggest that intermittent suction increased the efficacy of coronary venous retroinfusion in acute myocardial ischaemia.     

Unusual congenital coronary anomaly and myocardial ischaemia

Angiography was used to diagnose a rare congenital coronary anomaly with myocardial ischaemia in a woman with typical angina. All three coronary arteries arose from a solitary coronary ostium in the right aortic sinus; the left anterior descending coronary artery followed a septal course, the circumflex coronary artery ran behind the ascending aorta, and the right coronary artery followed a normal course. No significant coronary lumen narrowing was found. Transoesophageal echocardiography confirmed the anomalous origin and course of the aberrant coronary arteries. An exercise test reproduced angina, and ECG changes and myocardial perfusion study showed an anterior reversible defect. In contrast to previous reports, myocardial ischaemia was associated with the septal (intramuscular) course of the left anterior descending coronary artery; there was no other significant coronary artery disease.


Keywords: congenital heart defects; myocardial ischaemia; angiography; echocardiography     

Diastolic retroperfusion of acutely ischemic myocardium.

The effectiveness of coronary venous retroperfusion treatment of an ischemic myocardial segment was assessed by measurements of regional and global myocardial function in 16 dogs. The left anterior descending coronary artery was acutely occluded for 75 minutes. After the first 30 minutes of occlusion, diastolic retroperfusion was instituted for 45 minutes by synchronized pumping of arterial blood from the brachial artery into the anterior interventricular coronary vein. Data collected in the preocclusion control period, during occlusion and the subsequent retroperfusion period included simultaneous measurement os ischemic and border zone myocardial forces, epicardial electrocardiographic S-T segments, intracoronary pressure, coronary blood flow and oxygen pressure (PO2) sampled distal to the site of occlusion. Retroperfusion resulted in significant improvement from the level of regional dysfunction observed after 30 minutes of occlusion: Ischemic zone myocardial force increased 106%, epicardial S-T elevation decreased 46%, normalized peripheral left anterior descending coronary arterial flow increased 50% and distal left anterior descending PO2 decreased 44%. These regional improvements were significant when compared with findings in an untreated series of 12 dogs with 75 minutes occlusion of the left anterior descending coronary artery. Diastolic-augmented coronary venous retroperfusion with arterial blood provided significant but not complete restoration of function in the ischemic segment. Therefore, in the earliest phase of acute myocardial infarction, retroperfusion might represent a useful temporary support to an otherwise inaccessible jeopardized zone of the heart. Regional retroperfusion may constitute an effective emergency procedure, particularly when the occlusive lesions are diffuse and other medical or surgical emergency procedures are inadvisable, unavailable or ineffective.     

Differential effects of left anterior descending coronary occlusion on left and right ventricular anterior wall thickening in the conscious pig.

OBJECTIVE: In humans, the left anterior descending coronary artery supplies the left ventricular wall, anterior septum and the paraseptal part of the right ventricular anterior wall. Our aim was to study the effects of acute left anterior descending coronary occlusion on wall thickening in the regions of the left and right ventricular anterior walls supplied by the artery, and in remote, non-ischaemic regions of both ventricles. METHODS: Systolic wall thickening (defined as percent thickening with respect to end diastolic wall thickness) was studied in eight conscious pigs every 15 s during 1 min of acute left anterior descending coronary occlusion by a cuff occluder, and every 30 s during 4 min of reperfusion. Pigs were instrumented with ultrasonic microcrystals measuring wall thickness in the anterior walls (left anterior descending artery territory) and lateral walls (left circumflex or right coronary artery territory) of both ventricles, and a left ventricular pressure microtransducer. RESULTS: During control and reperfusion, both anterior walls displayed similar systolic thickening. During coronary occlusion, the left ventricular anterior wall showed paradoxical systolic thinning (dyskinesia) whereas the right ventricular anterior wall showed only hypokinesia. CONCLUSIONS: In the presence of equal blood flow deprivation, the right ventricular anterior wall supplied by the left anterior descending coronary artery displays a significantly lesser degree of functional impairment than the left ventricular anterior wall supplied by the same artery. This differential effect may be due to mechanical unloading of the right ventricular anterior wall resulting from left ventricular anterior wall ischaemia. This afterload reduction due to decreased mechanical interaction between the two walls would allow the right ventricular anterior wall to express its contractile reserve in the form of systolic thickening.     

Contrasting effects of dopamine and dobutamine on myocardial release of norepinephrine during acute myocardial infarction

The effects of dopamine and dobutamine on release of norepinephrine from normal and ischemic myocardium were compared in 2 groups of open-chest anesthetized dogs. Both agents were infused intravenously at a rate of 10 micrograms/Kg/min for 2 hours, beginning 40 min after snare occlusion of the left anterior descending coronary artery. There were no major differences in hemodynamic responses between the 2 groups. Blood samples were taken simultaneously from the aorta, coronary sinus and the cardiac vein that ran parallel to the left anterior descending coronary artery before and after coronary artery occlusion. Plasma norepinephrine increased 40 min after the occlusion, with a net efflux in both coronary sinus and cardiac venous blood. Dopamine caused further increases in plasma norepinephrine. At 20 min after the beginning of dopamine infusion the coronary sinus concentration (4.09 +/- 1.36 ng/ml) was significantly greater than the arterial concentration (2.84 +/- 0.87 ng/ml). This transcardiac difference disappeared during continuous infusion 2 hours after coronary artery occlusion. Differences in norepinephrine concentration between the arterial and cardiac venous blood, however, were not significant. In contrast, plasma norepinephrine did not increase during dobutamine infusion in either the ischemic or non-ischemic bed. Thus, the results suggest that while these two agents have similar systemic hemodynamic effects, only dopamine increases myocardial release of norepinephrine from either ischemic or normal myocardium during acute myocardial infarction.     

Coronary sinus pH during percutaneous transluminal coronary angioplasty: early development of acidosis during myocardial ischaemia in man

Coronary sinus pH was measured continuously in eight patients undergoing angioplasty to the left anterior descending coronary artery. A catheter tip pH sensitive electrode with a response time of less than 300 ms and an output of greater than or equal to 57 mV/pH unit was placed high in the coronary sinus. Recordings were obtained during a total of 24 balloon occlusions of the left anterior descending coronary artery varying in duration from 5 to 45 s. Continuous 12 lead surface electrocardiograms were recorded. During or after balloon inflation of greater than or equal to 12 s (n = 4) there was no change in coronary sinus pH or the electrocardiogram. During balloon inflation of greater than or equal to 15 s (n = 20) coronary sinus pH was unaltered but between 4 and 6 s after balloon deflation coronary sinus pH fell transiently by between 0.010 and 0.120 pH units before returning to the control value within 65 s. Ischaemic changes were seen on the electrocardiogram during 15 balloon occlusions. In individual patients the peak fall in coronary sinus pH was related to the duration of occlusion of the left anterior descending coronary artery. A rise in coronary sinus pH (alkalosis) was never seen. In man acidosis occurs in the myocardium after short periods (greater than or equal to 12 s) of ischaemia. The fall of pH precedes ischaemic changes on the surface electrocardiogram and occurs concurrently with the earliest reported changes in contractile function.     

Coronary sinus pH during percutaneous transluminal coronary angioplasty: early development of acidosis during myocardial ischaemia in man.

Coronary sinus pH was measured continuously in eight patients undergoing angioplasty to the left anterior descending coronary artery. A catheter tip pH sensitive electrode with a response time of less than 300 ms and an output of greater than or equal to 57 mV/pH unit was placed high in the coronary sinus. Recordings were obtained during a total of 24 balloon occlusions of the left anterior descending coronary artery varying in duration from 5 to 45 s. Continuous 12 lead surface electrocardiograms were recorded. During or after balloon inflation of greater than or equal to 12 s (n = 4) there was no change in coronary sinus pH or the electrocardiogram. During balloon inflation of greater than or equal to 15 s (n = 20) coronary sinus pH was unaltered but between 4 and 6 s after balloon deflation coronary sinus pH fell transiently by between 0.010 and 0.120 pH units before returning to the control value within 65 s. Ischaemic changes were seen on the electrocardiogram during 15 balloon occlusions. In individual patients the peak fall in coronary sinus pH was related to the duration of occlusion of the left anterior descending coronary artery. A rise in coronary sinus pH (alkalosis) was never seen. In man acidosis occurs in the myocardium after short periods (greater than or equal to 12 s) of ischaemia. The fall of pH precedes ischaemic changes on the surface electrocardiogram and occurs concurrently with the earliest reported changes in contractile function.     

Mechanism of remote myocardial ischaemia after coronary occlusion in open chest dogs

To determine whether or not the fall in coronary perfusion pressure after coronary occlusion is the cause of remote myocardial ischaemia, regional myocardial blood flow was measured using radiolabelled microspheres before and after left anterior descending (LAD) occlusion in the presence of a left circumflex artery stenosis in 22 anaesthetised dogs. Aortic pressure was maintained constant at the time of left anterior descending artery occlusion in 13 dogs (group 1) and proximal left circumflex artery pressure was held constant by a servocontrolled pump in nine dogs with a carotid artery-left circumflex artery shunt (group 2). Despite the maintenance of constant mean aortic pressure in group 1, remote posterior bed mean(SEM) endocardial flow fell from 0.69(0.05) to 0.43(0.07) ml.min-1.g-1 (p less than 0.05). In the dogs in which left atrial pressure rose to less than or equal to 9 mmHg after left anterior descending artery occlusion, remote bed endocardial flow did not fall significantly (0.66(0.07) to 0.56(0.11) ml.min-1.g-1; NS). In contrast, remote bed endocardial flow fell from 0.73(0.07) to 0.28(0.06) ml.min-1.g-1 (p less than 0.0001) after left anterior descending artery occlusion in the dogs in which left atrial pressure rose to greater than 9 mmHg. The fall in remote bed endocardial flow was prevented in group 2 dogs by maintaining proximal left circumflex artery pressure constant (0.95(0.08) to 0.86(0.09) ml.min-1.g-1; NS). An important mechanism for the development of remote myocardial ischaemia appears to be the fall in proximal coronary perfusion pressure at the time of coronary occlusion.     

Intravascular echocardiography (ICUS) diagnosis of post-traumatic coronary dissection involving the common trunk. A case report and review of the literature]

A case is reported in which a 31-years-old man experienced coronary artery dissection with an acute anterior myocardial infarction following blunt chest trauma in a car accident. Due to ECG signs of acute myocardial infarction a coronary angiography was performed showing an abrupt occlusion of the mid part of the left anterior descending artery and a linear filling defect in the proximal portion of the vessel. Additional detailed intravascular ultrasound was performed, revealing a long intimal tear involving the left anterior descending artery and the left main. The patient underwent immediate coronary artery bypass surgery. Two vein grafts were made from aorta to the left anterior descending artery and the circumflex artery, respectively. Repeat angiography was performed early after the operation; dissection of the left main and the left anterior descending artery was still visible and the grafts to the left descending artery and the circumflex were patent.     

Percutaneous approach to a stent-based ventricle to coronary vein bypass (venous VPASS): comparison to catheter-based selective pressure-regulated retro-infusion of the coronary vein.

AIMS: Percutaneous stent-based ventricle-to-coronary vein bypass (venous VPASS) is a new approach to chronic venous arterialization as a treatment modality in an otherwise no option patient with coronary artery disease. In this study, the efficacy of venous VPASS was compared with catheter-based selective pressure-regulated retro-infusion of arterial blood during acute ischaemia. METHODS AND RESULTS: In seven pigs, venous VPASS was established using a percutaneous ultrasound-guided puncture from the anterior cardiac vein to the left ventricle, with subsequent implantation of an ePTFE-covered stent graft. During left anterior descending artery (LAD) occlusion, coronary venous pressure in the distal anterior cardiac vein increased to 55+/-4 mmHg under conditions of venous VPASS compared with 78+/-5 mmHg during selective pressure-regulated retro-infusion. Significant preservation of regional myocardial function was observed during venous VPASS (67+/-6% baseline) and during selective retro-infusion (83+/-4%) compared with control LAD occlusion (0.4+/-2%). CONCLUSION: Percutaneous implantation of a PTFE covered stent (venous VPASS) was feasible and associated with significant preservation of regional myocardial function during acute ischaemia in pigs at reasonable levels of mean coronary venous pressure to avoid tissue damage during chronic application.     

Effects of pressure-controlled intermittent coronary sinus occlusion on regional ischemic myocardial function

Pressure-controlled intermittent coronary sinus occlusion has been reported to reduce infarct size in dogs with coronary artery occlusion, possibly because of increased ischemic zone perfusion and washout of toxic metabolites. The influence of this intervention on regional myocardial function was investigated in open and closed chest dogs. In six open chest dogs with severe stenosis of the left anterior descending coronary artery and subsequent total occlusion, a 10 minute application of intermittent coronary sinus occlusion increased ischemic myocardial segment shortening from 5.5 +/- 1.2 to 8.2 +/- 2.6% (NS) and from -0.1 +/- 2.1 to 2.3 +/- 1.2% (NS), respectively. In eight closed chest anesthetized dogs, intermittent coronary sinus occlusion was applied for 2.5 hours between 30 minutes and 3 hours of intravascular balloon occlusion of the proximal left anterior descending coronary artery. Standardized two-dimensional echocardiographic measurements of left ventricular function were performed to derive systolic sectional and segmental fractional area changes in five short-axis cross sections of the left ventricle. Fractional area change in all the severely ischemic segments (less than 5% systolic wall thickening) was -4.0 +/- 4.7% at 30 minutes after occlusion, and increased with subsequent 60 and 150 minutes of treatment to 13.1 +/- 3.3 and 7.0 +/- 3.3%, respectively (p less than 0.05). At the most extensively involved low papillary muscle level of the ventricle, regional ischemic fractional area change was increased by intermittent coronary sinus occlusion between 30 and 180 minutes of coronary occlusion from -0.4 +/- 0.1 to 14.4 +/- 4% (p less than 0.05), whereas a further deterioration was noted in untreated dogs with coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)