Functional characteristics of a new coronary perfusion balloon: Comparison with the flowtrack 40 in closed chest swine

This study was designed to compare a new investigational coronary perfusion balloon (Wave, Scimed Life Systems Inc.) with that of an approved, widely used, current generation device (Flowtrack 40, Advanced Cardiovascular Systems). Domestic swine were anesthetized with pentobarbital and instrumented using standard percutaneous technique. Left ventricular contractile function (dP/dt) was monitored using a micromanometer while intracoronary and surface ECGs were also recorded. Eight target vessels were studied (4 LAD and 4 Cx) in random order. The perfusion balloons were kept inflated for 10 min. Complete coronary occlusion with a standard angioplasty balloon produced marked decreases in mean aortic pressure, left ventricular developed pressure, peak + dP/dt, peak -dP/dt, and significant ST segment elevation in both intracoronary and surface ECG at 30 seconds. Neither the Wave or Flowtrack 40 produced any change in heart rate or mean aortic pressure. Both catheters caused a drop in left ventricular developed pressure immediately after balloon inflation. At 10 min, however, there was a small but significant decrease only with the Flowtrack 40. Similarly, peak + dP/dt was slightly depressed during Flowtrack 40 inflation at 10 min but not with the Wave catheter. Both catheters produced ST segment elevation on the surface and intracoronary electrocardiographic records. These changes were significantly greater with the Flowtrack 40 system. Thus, both the Flowtrack 40 and Wave perfusion balloons are effective in preventing ischemia during coronary occlusion in swine; however, the latter system may be more effective in this model. © 1995 Wiley-Liss, Inc.     

Repeated coronary artery occlusions during routine balloon angioplasty do not induce myocardial preconditioning in humans

Objectives.The purpose of the present study was to assess whether brief, repeated coronary artery occlusions during balloon angioplasty induce a myocardial ischemic protective effect.Background.In animals, brief coronary artery occlusions preceding a more prolonged occlusion result in reduced infarct size. Whether myocardial protection against ischemia could also occur in humans during angioplasty remains controversial.Methods.Thirteen patients with a proximal left anterior descending coronary artery stenosis with no angiographic collateral circulation underwent percutaneous transluminal coronary artery balloon angioplasty. Three 120-s balloon inflations separated by a 5-min equilibrium period were performed. For each inflation, intracoronary ST segment modifications, septal wall thickening (M-mode echocardiography), left ventricular pressures and time derivatives were measured at baseline and at 30, 60 a d 90 s after balloon inflation and 120 s after balloon deflation.Results.Intracoronary electrocardiographic analysis showed that the time course of the maximal ST segment elevation was identical at each inflation, as were wall motion changes assessed by the decrease in septal wall thickening. For the first and last inflations, peak positive dP/dt decreased significantly by 13 ± 9% (mean ± SD) and 14 ± 13%, whereas peak negative dP/dt increased by 23 ± 15% and 22 ± 10%, respectively (all p < 0.01 from baseline values). The relaxation time constant, tau, was altered similarity during the different inflations, from 44 ± 6 to 74 ± 13 ms and from 57 ± 13 to 77 ± 13 ms (all p < 0.001) for the first and last inflations, respectively. Left ventricular endiastolic pressure increased to the same level after each inflation. In contrast to other hemodynamic variables, tau and left ventricular end-diastolic pressure did not return to baseline values in between the inflations, which may be due to myocardial stunning.Conclusions.In patients with proximal left anterior descending coronary artery stenosis and no evidence of collateral circulation, brief periods of ischemia, such as those used during routine coronary balloon angioplasty, do not provide any protection against myocardial ischemia.     

The functional significance of coronary collateral circulation during sudden coronary occlusion]

The functional significance of the coronary collateral circulation remains controversial. It has been suggested that collateral circulation possibly helps prevent myocardial ischemia. Seventeen target lesions in 15 patients were studied to determine the relationship between the extent of the coronary collateral circulation and the degree of ventricular dysfunction during percutaneous transluminal coronary angioplasty (PTCA). During the first balloon inflation, diastolic indices such as left ventricular end-diastolic pressure, max negative dP/dt and the time constant of early relaxation were measured immediately before and at 60 sec following balloon inflation. During the second inflation, the contralateral and ipsilateral collateral circulations were evaluated. The latter was graded as follows: 0 = none; I = filling of side branches only; II = partial filling of the epicardial segment; and III = complete filling of the epicardial segment. Following balloon inflation, a significant increase was noted in the time constant of early relaxation in patients with grade 0 collateral circulation (40 +/- 7 to 47 +/- 7 msec: p < 0.01) and grade II collateral circulation (52 +/- 12 to 56 +/- 13 msec: p < 0.05). The percent increase in the time constant of early relaxation of patients with grade 0 and I collateral circulations exceeded that of patients with grade II (p < 0.05) or grade III collateral circulation (p < 0.05). Left ventricular end-diastolic pressure was elevated in all groups during PTCA. There was no significant difference in the percent increase of left ventricular end-diastolic pressure (LVEDP) between the 4 groups. However, LVEDP before PTCA was higher in patients with grade III collateral circulation than in patients in the other groups. Max negative dP/dt did not change significantly in any group. In conclusion, collateral circulation helps prevent myocardial ischemia during acute coronary occlusion, which is most precisely shown by the time constant of early relaxation. The degree of this protective function of collateral circulation seems to vary.     

Limitation of myocardial ischemia by collateral circulation during sudden controlled coronary artery occlusion in human subjects: a prospective study

We have shown improvement in collateral filling immediately after sudden controlled coronary occlusion in human subjects undergoing elective coronary angioplasty. It has been suggested but not proved that collateral circulation can limit myocardial ischemia. We prospectively studied 23 patients with isolated left anterior descending (n = 14) or right coronary (n = 9) disease and normal left ventriculograms during elective coronary angioplasty. A second arterial catheter was used for injection of the contralateral artery to assess collateral filling before balloon placement and during coronary occlusion by balloon inflation. Left ventriculography was performed during another inflation. Grading of collateral filling was as follows: 0 = none, 1 = filling of side branches only, 2 = partial filling of the epicardial segment, 3 = complete filling of the epicardial segment. Indexes of myocardial ischemia included percent of the left ventricular perimeter showing new hypocontractility and the sum of ST segment elevation measured on a simultaneous 12-lead electrocardiogram recorded during each inflation. Collateral filling during balloon occlusion and indexes of ischemia were assessed at 30 to 40 sec into inflation. Aortic pressure and heart rate did not correlate with the percent hypocontractile perimeter nor the sum of ST segment elevation. There was a significant correlation between the grade of collateral filling during inflation and both percent hypocontractile perimeter (r = -.85) and the sum of ST segment elevation (r = -.87). Anginal pain occurred in all patients with grade 0 or 1 collateral filling but in only 36% of patients with grade 2 or 3 collaterals. In conclusion, collateral circulation limits myocardial ischemia as assessed by the extent of new ventricular asynergy and electrocardiographic changes during coronary occlusion in patients.     

Myocardial protection by coronary autotransfusion during angioplasty

Coronary autologous blood perfusion may protect the myocardium against ischemia during arterial occlusion due to balloon inflation. During balloon inflation, arterial blood was perfused via the balloon catheter in 19 patients with single proximal severe left anterior descending artery stenosis and normal left ventricular function. Blood was perfused using a contrast medium injector at a flow rate of 40 ml/min. The balloon was maintained inflated for 60 seconds at 6 atmospheres. Two inflations were performed with perfusion and 2 without. Myocardial ischemia was assessed by ST elevations on both the peripheral and intracoronary ECGs, changes in left ventricular systolic and end diastolic pressures and peak positive and negative dP/dt. A positive response was obtained in 11 patients. In 5 patients, the myocardial ischemia induced by dilatation was not alleviated by the perfusion and in 3 patients ischemia was increased by perfusion. In conclusion, ischemia is inconsistently reduced by autologous blood perfusion and its adverse effect in some patients could limit its use.     

Protective effect of collateral vessels during coronary angioplasty

To assess the potential protective role of collateral vessels 27 patients undergoing angioplasty of the left anterior descending coronary artery were studied by intravenous digital subtraction left ventriculography. Fifteen patients had no collateral vessels (group 1) and 12 had some degree of collateral supply (group 2). During balloon inflation ST segment elevation in group 1 (4.9 mm) was significantly greater than that in group 2 (0.9 mm). Similarly the reduction in left ventricular ejection fraction was significantly greater in group 1 (24%) than in group 2 (12%). Both the size of ST segment elevation and the fall in ejection fraction correlated inversely with the extent of the collateral supply (r = -0.680 and r = -0.446 respectively). During balloon occlusion of the anterior descending coronary artery the percentage shortening of the anterior and apical segments fell in both groups but apical shortening fell to a lesser extent in group 2. An additional reduction in anterobasal contraction was confined to group 1. Electrocardiographic and ventriculographic manifestations of ischaemia produced by balloon inflation during angioplasty are less pronounced when collateral vessels are present. This suggests that the collateral circulation can protect myocardium at risk of ischaemia after coronary occlusion.     

Protective effect of collateral vessels during coronary angioplasty.

To assess the potential protective role of collateral vessels 27 patients undergoing angioplasty of the left anterior descending coronary artery were studied by intravenous digital subtraction left ventriculography. Fifteen patients had no collateral vessels (group 1) and 12 had some degree of collateral supply (group 2). During balloon inflation ST segment elevation in group 1 (4.9 mm) was significantly greater than that in group 2 (0.9 mm). Similarly the reduction in left ventricular ejection fraction was significantly greater in group 1 (24%) than in group 2 (12%). Both the size of ST segment elevation and the fall in ejection fraction correlated inversely with the extent of the collateral supply (r = -0.680 and r = -0.446 respectively). During balloon occlusion of the anterior descending coronary artery the percentage shortening of the anterior and apical segments fell in both groups but apical shortening fell to a lesser extent in group 2. An additional reduction in anterobasal contraction was confined to group 1. Electrocardiographic and ventriculographic manifestations of ischaemia produced by balloon inflation during angioplasty are less pronounced when collateral vessels are present. This suggests that the collateral circulation can protect myocardium at risk of ischaemia after coronary occlusion.     

Does intracoronary infusion of Fluosol-DA 20% prevent left ventricular diastolic dysfunction during coronary balloon angioplasty?

Distal intracoronary infusion of the perfluorochemical Fluosol-DA 20% has been shown to prevent systolic dysfunction during coronary artery balloon occlusion in coronary angioplasty. To assess its effect on global diastolic dysfunction, a randomized, single-blind, crossover protocol comparing intracoronary infusion of Fluosol or no infusion (control) was performed during 60 s balloon inflations in 10 patients (mean age 67 years) undergoing coronary angioplasty. Assessment of global systolic and diastolic function was obtained with high fidelity micromanometer measurements of left ventricular pressure. Eighteen pairs of balloon inflations (Fluosol versus control) were analyzed. Patients reported significantly less severe chest pain during inflations accompanied by Fluosol compared with control. However, during coronary balloon occlusion, no significant differences in the changes from baseline values were observed between Fluosol and control with regard to ventricular relaxation, including the time constant of early ventricular relaxation (tau) and maximal rate of fall in left ventricular pressure (maximal negative dP/dt). No differences between Fluosol and control were observed in terms of the increase in end-diastolic pressure or minimal diastolic pressure during balloon inflation. Mean systolic pressure decrease from baseline values was greater during control than during Fluosol inflations (-9.0 +/- 3.3 mm Hg, p = 0.013), but no significant difference was observed in the change in maximal rate of rise in left ventricular pressure (maximal positive dP/dt). These results suggest that Fluosol does not preserve global left ventricular diastolic function during coronary balloon occlusion, possibly because of its limited oxygen delivery capability relative to arterial blood.     

Absence of myocardial ischemia during sudden controlled occlusion of coronary arteries in patients with well-developed collateral vessels

OBJECTIVE: To determine whether the presence of well-developed collateral vessels (visualized by baseline angiography) prevents myocardial ischemia associated with electrocardiographic ST-segment deviation or anginal pain during subsequent coronary balloon occlusion. METHODS: Study patients with stable effort angina but without complete coronary obstruction were divided into two groups on the basis of whether myocardial ischemia was observed during the first minute of coronary balloon occlusion in order to compare the degrees of collateral development at baseline. Patients in group A (n = 47) had electrocardiographic ischemic ST-segment deviations or angina, or both, during balloon inflation, whereas patients in group B (n = 13) had neither. RESULTS: The incidences both of poor anterograde perfusion with TIMI grade 1 or 2 (77 versus 38%, P < 0.05) and of well-developed collateral vessels (Rentrop grade 3) in the perfusion territory of the target vessel for coronary angioplasty (77 versus 15%, P < 0.01) were higher for patients in group B than they were for those in group A. The incidence of no myocardial ischemia during balloon inflation among the patients with well-developed collateral vessels was higher than that among those without (59 versus 7%, P < 0.01). The prediction of the absence of myocardial ischemia during balloon inflation according to whether well-developed collateral vessels were present had the sensitivity 77% (10 of 13) and the specificity 93% (40 of 43) for the study patients. CONCLUSION: Absence of myocardial ischemia (revealed by electrocardiographic changes or angina during transient coronary balloon occlusion) was associated with presence of well-developed collateral vessels (Rentrop grade 3; visualized by baseline angiography), suggesting that the patients with well-developed collateral vessels have a low risk of developing acute myocardial infarction or hemodynamic instability upon abrupt closure of the culprit coronary artery.     

Neurally mediated depressor hemodynamic response induced by intracoronary catheter balloon inflation in pigs

OBJECTIVES: To assess whether intracoronary catheter balloon inflation triggers a neurally mediated hemodynamic response that interacts with the ischemia-induced myocardial dysfunction. METHODS: Forty-eight chloralose anesthetized pigs underwent a 60 s intraluminal catheter balloon inflation of the proximal left anterior descending (LAD) coronary artery before and after one of these treatments: disruption of LAD pericoronary nerves with phenol (n=6), bilateral stellectomy (n=8), bilateral cervical vagotomy (n=6), atropine (n=5), and ganglionic blockade with hexamethonium (n=10). In 13 other pigs, we assessed the reproducibility of two balloon inflations spaced 15 min (n=6) or 60 min (n=7). The ECG, left ventricular (LV) pressure, and LV dP/dt were recorded during each intervention. Right ventricular (RV) pressure, RV dP/dt, and aortic blood flow were also measured in a subset of pigs. RESULTS: Balloon inflation induced an early (10 s) and reproducible (ANOVA, P<0.001) drop in systolic pressure and peak dP/dt; a decrease in aortic blood flow; a rise in end-diastolic pressure; and elevation of the ST segment. Pericoronary denervation, stellectomy and ganglionic blockade attenuated (P<0.001) the drop in LV parameters during coronary inflation, but atropine and vagotomy did not. CONCLUSIONS: A depressor hemodynamic response subserved by pericoronary nerves worsens the LV dysfunction induced by brief coronary catheter balloon inflation in anesthetized pigs. Cholinergic fibers do not appear to play a major role.     

Assessment of left ventricular performance during percutaneous transluminal coronary angioplasty: a study by intravenous digital subtraction ventriculography

Left ventricular performance during percutaneous transluminal coronary angioplasty was assessed in 52 patients by intravenous digital subtraction ventriculography. After injection of contrast into the right atrium ventriculograms were obtained before and during balloon inflation. In 37 patients they were also obtained after the procedure. A 12 lead electrocardiogram was monitored throughout. During balloon inflation the left ventricular ejection fraction fell (from 73% to 57%) in all but one patient; the decreases in patients with single vessel or multivessel disease were similar. The fall in left ventricular ejection fraction during percutaneous transluminal coronary angioplasty of the left anterior descending artery (19%) was significantly greater than that during balloon inflation in the right coronary (10%) or circumflex (8%) coronary arteries. It also reduced anterobasal, anterior, and apical segmental shortening while right coronary percutaneous transluminal coronary angioplasty affected inferior and apical segments. In 33 (63%) patients the ST segment was altered during balloon inflation. The fall in left ventricular ejection fraction correlated significantly with the magnitude of both ST segment elevation (r = 0.637) and ST depression (r = 0.396). Left ventricular ejection fraction and regional wall motion returned to baseline values after the procedure. Balloon inflation during percutaneous transluminal coronary angioplasty produces considerable abnormalities of global and regional left ventricular performance and this indicates the presence of myocardial ischaemia, which may not be apparent on electrocardiographic monitoring. Intravenous digital subtraction ventriculography is useful for monitoring left ventricular performance during controlled episodes of coronary occlusion produced by balloon inflation.     

The efficacy of intermittent coronary sinus occlusion in the absence of coronary artery collaterals

The purpose of this study was to evaluate the efficacy of time-controlled intermittent coronary sinus occlusion (ICSO) in preserving regional and global mechanical function during acute ischemia in an animal preparation without significant arterial collateral vessels. Seventeen (eight control, nine ICSO) swine heart preparations undergoing extracorporeal coronary perfusion in situ were subjected to ligation of the left anterior descending coronary artery (LAD) distal to the first major diagonal branch. Data were obtained before and immediately after coronary artery ligation in both animal groups. ICSO, 15 sec of occlusion alternating with 5 sec of release, was then begun in the treatment group. Additional data were obtained in both control and treatment groups at 15 min intervals for 1 hr starting immediately after coronary artery ligation. Global left ventricular function was assessed by shifts in left ventricular end-diastolic pressure and left ventricular dP/dt with left ventricular systolic pressure maintained at about 100 mm Hg. Regional mechanical function was evaluated with transmurally placed ultrasonic crystals. Pressure was also measured directly in the coronary sinus and LAD distal to the ligature. Regional myocardial blood flow was measured in the ischemic bed using 9 micron diameter radiolabeled microspheres injected before, immediately after, and 60 min after coronary artery ligation in both treated and control animals. LAD mean pressure measured distal to the ligation (less than 16 mm Hg) and ischemic bed myocardial blood flow (less than 0.01 ml/g/min) confirmed the absence of significant arterial-arterial collaterals in this preparation. Mean coronary sinus pressure increased significantly (p less than .001) in treated animals during ICSO (e.g., 11.2 +/- 1.6 to 66.2 +/- 10.0 mm Hg at 15 min after coronary ligation). Mean LAD pressure distal to the coronary ligature also increased during ICSO (14.2 +/- 1.2 to 26.8 +/- 1.6 mm Hg), with a similar but delayed rate of pressure rise. No significant differences in left ventricular end-diastolic pressure or left ventricular dP/dt were noted between control or treated animals after coronary ligation. Ischemic bed systolic wall thickening, present before coronary ligation, was not present after occlusion and was not improved during intermittent coronary sinus occlusion in the treatment group. We conclude that in an animal preparation without significant collateral circulation, intermittent coronary sinus occlusion is incapable of restoring regional or global left ventricular mechanical function during conditions of acute ischemia.     

Assessment of left ventricular performance during percutaneous transluminal coronary angioplasty: a study by intravenous digital subtraction ventriculography.

Left ventricular performance during percutaneous transluminal coronary angioplasty was assessed in 52 patients by intravenous digital subtraction ventriculography. After injection of contrast into the right atrium ventriculograms were obtained before and during balloon inflation. In 37 patients they were also obtained after the procedure. A 12 lead electrocardiogram was monitored throughout. During balloon inflation the left ventricular ejection fraction fell (from 73% to 57%) in all but one patient; the decreases in patients with single vessel or multivessel disease were similar. The fall in left ventricular ejection fraction during percutaneous transluminal coronary angioplasty of the left anterior descending artery (19%) was significantly greater than that during balloon inflation in the right coronary (10%) or circumflex (8%) coronary arteries. It also reduced anterobasal, anterior, and apical segmental shortening while right coronary percutaneous transluminal coronary angioplasty affected inferior and apical segments. In 33 (63%) patients the ST segment was altered during balloon inflation. The fall in left ventricular ejection fraction correlated significantly with the magnitude of both ST segment elevation (r = 0.637) and ST depression (r = 0.396). Left ventricular ejection fraction and regional wall motion returned to baseline values after the procedure. Balloon inflation during percutaneous transluminal coronary angioplasty produces considerable abnormalities of global and regional left ventricular performance and this indicates the presence of myocardial ischaemia, which may not be apparent on electrocardiographic monitoring. Intravenous digital subtraction ventriculography is useful for monitoring left ventricular performance during controlled episodes of coronary occlusion produced by balloon inflation.     

Clinical characteristics of coronary artery spasm: electrocardiographic, hemodynamic and arteriographic assessment

We studied the clinical characteristics of 153 patients with angina pectoris associated with coronary artery spasm (CAS). The study was designed to investigate the relationship of CAS to ST segment deviation and to the site of fixed stenosis, and hemodynamic alteration during a spastic event. Analysis of coronary arteriograms and multilead electrocardiograms obtained simultaneously from 170 events of CAS by the use of radioluscent carbon-fiber electrodes resulted in 58 events with ST elevation which were related to total occlusion of major coronary arteries due to CAS; another 54 events with ST depression, in which the affected coronary arteries demonstrated severe but incomplete occlusion, or total occlusion but were visualized via collateral vessels; and remaining 58 events without ST deviation showing mild occlusion. The results indicate a close correlation between magnitude of CAS and ST segment deviation. CAS occurred at the site of pre-existing fixed stenosis including minor plaque defect in 133 patients and at apparently normal site in 20 patients. In the former group, only four patients had triple vessel disease, while 95 had nonsignificant fixed lesion. In the latter group, 10 patients had minor lesion distant from the site of CAS. Thus, CAS is closely related to fixed stenosis, which may have but a limited role as a cause of CAS. Hemodynamic measurements during spastic events were obtained from 49 patients including 41 events with spasm of the left anterior descending artery (LAD) and 21 events with spasm of the right coronary artery (RCA). The onset of an increase in left ventricular (LV) filling pressure and a reduction in LV dP/dt preceded ST segment deviation in all events. The first hemodynamic variable manifested in the spastic event was the reduction of LV contraction dP/dt in the majority of patients. The increase of LV filling pressure was greater in LAD spasm than RCA spasm (11 +/- 6 mmHg vs 7 +/- 4 mmHg, P less than 0.0125) and in events with ST elevation than with ST depression (11 +/- 5 mmHg vs 6 +/- 5 mmHg, p less than 0.001). Right ventricular functional impairment was mild in most patients during CAS. The study indicates that mechanical impairment precedes electrical impairment during CAS and that LAD spasm with ST elevation represents the most severe LV dysfunction.     

ST segment response to acute coronary occlusion: coronary hemodynamic and angiographic determinants of direction of ST segment shift

To assess the relationship between the direction of ST segment response to transient coronary occlusion and collateral function, we studied 25 patients with diagnostic ST segment changes during transient occlusion of the proximal left anterior descending artery (LAD). Electrocardiographic leads I, II, V2, and V5; left ventricular filling, aortic, and distal coronary pressures; and great cardiac vein flow were measured during percutaneous transluminal coronary angioplasty (PTCA) of the LAD. During a 1 min LAD balloon occlusion, 16 patients had reversible ST elevation (group I) and nine patients had ST depression (group II). The ST responses in individual patients were consistent during repeated occlusions, and ST depression never preceded ST elevation. Angiography before PTCA showed less severe LAD stenosis in group I (69 +/- 15%) than in group II (88 +/- 10%; p less than .01) and collateral filling of the LAD in no group I patient but in six of nine patients in group II (p less than .01). During LAD occlusion, determinants of myocardial oxygen demand (left ventricular filling pressure, aortic pressure, heart rate, and double product) were similar in both groups. Group I patients, however, had lower distal coronary pressure (25 +/- 8 vs 41 +/- 16 mm Hg) and residual great cardiac vein flow (33 +/- 14 vs 51 +/- 22 ml/min) and higher coronary collateral resistance (3.1 +/- 2.1 vs 1.5 +/- 0.8 mm Hg/ml/min) than group II patients (all p less than .05). In patients with ST elevation during LAD occlusion, stenosis before PTCA was less severe, visible collaterals were not present, and hemodynamic variables during LAD occlusion reflected poorer collateral function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Deleterious cardiac effects of captopril during acute myocardial ischaemia in the dog.

OBJECTIVE: The aim was to evaluate the effects of the angiotensin converting enzyme inhibitor captopril on acute myocardial ischaemia. METHODS: Seventeen anaesthetised open chest dogs were randomised to 3 minute angioplasty balloon occlusions of the left circumflex coronary artery before and after intravenous infusion of captopril (n = 8) or placebo (n = 9). RESULTS: There was apparent worsening of ischaemia during balloon inflation after captopril infusion, when compared with control inflation, as suggested by further ST segment elevation of 1.8 (SD 1.8) mm, p less than 0.03, and by further lowering of regional myocardial pH [-0.05(0.05), p = 0.06], and peak positive and peak negative dP/dt [-439(337)mm Hg.s-1, p less than 0.008; -470(316) mm Hg.s-1, p less than 0.004, respectively]. The increase in ischaemia occurred despite reduced double product after captopril administration. Regional myocardial blood flow in the ischaemic artery distribution was lower during post captopril balloon occlusion [-0.1(0.06) ml.min-1.g-1, p less than 0.005] than during control balloon inflation, while coronary vascular resistance increased by 161(172)% (range 45 to 497%, p less than 0.04). There were no significant differences in ST segments, pH, haemodynamic variables, or blood flow during balloon inflations before and after saline infusion. CONCLUSIONS: Despite lower myocardial metabolic demands, acute intravenous administration of captopril was associated with increased ischaemia during transient coronary artery occlusion.     

Marked alternans of the elevated ST segment during occlusion of the left anterior descending coronary artery in percutaneous transluminal coronary angioplasty: clinical background and electrocardiographic features.

To investigate the clinical background and the electrocardiographic features of marked alternans of the elevated ST segment during coronary angioplasty, we examined 12-lead electrocardiograms recorded continuously during occlusion of the left anterior descending coronary artery by balloon inflation in 41 patients. The incidence of marked ST alternans was 27% of 41 patients and 15% of 117 balloon occlusions. The incidence decreased progressively from the first to the third occlusion. The time course of ST alternans was determined. Compared with patients without ST alternans, patients with ST alternans had a shorter history of angina, less severe stenosis of the target lesion before coronary angioplasty, more leads showing ST elevation during occlusion, higher ST elevation during occlusion and lower incidence of previous myocardial infarction in the left anterior descending coronary arterial area. ST alternans recorded on the surface electrocardiogram may thus be considered a marker of acute severe and extensive myocardial ischemia.     

"Ischemia at a distance" during intermittent coronary artery occlusion: a coronary anatomic explanation

The mechanism of electrocardiographic ST segment changes during acute coronary occlusion was evaluated in 28 consecutive patients with single vessel coronary artery disease undergoing coronary angioplasty. Patients were continuously monitored with a six lead electrocardiogram. Twenty-three patients showed ST changes in the primary zone of occlusion, and 13 of these had additional ST changes in a remote zone. Ten of these 13 had unusually extensive arteries supplying the remote zone. The balloon occluded two adjacent normal arteries in two patients, and no coronary anatomic explanation was evident in one patient. Ten patients with striking primary zone ST changes showed no remote change. Seven had nonextensive primary zone arteries, and three others had abundant collateral vessels. Five patients showed no electrocardiographic changes in primary or remote zones. Four had collateral vessels, and one had left ventricular hypertrophy on the baseline electrocardiogram. It was concluded that remote electrocardiographic changes are probably due to occlusion of unusually extensive coronary arteries and are not simply reciprocal.     

Comparison of ST-segment deviation to scintigraphically quantified myocardial ischemia during acute coronary occlusion induced by percutaneous transluminal coronary angioplasty

This study compared ST-segment changes during acute coronary artery occlusion with measurements of ischemia by myocardial scintigraphy. Forty patients who were referred for elective prolonged percutaneous transluminal coronary angioplasty underwent 12-lead electrocardiographic recording before the procedure (baseline) and continuously during the entire balloon inflation (occlusion). For each patient, the summed ST-segment deviation was calculated as the maximal absolute difference, elevation or depression, between baseline and occlusion recordings in all 12 leads. Each patient underwent 2 myocardial scintigraphies, 1 with technetium-99m sestamibi injected during the balloon inflation and 1 on the following day as a control study. Ischemia that was induced by balloon occlusion was quantified in terms of extent and severity. Results for the entire study group showed that summed ST deviation correlated with extent (r = 0.59, p < 0.0001) and severity (r = 0.61, p < 0.0001) of ischemia. The location of maximal ST deviation differed for the 3 arteries. For occlusion of the left anterior descending artery, maximal ST deviation was elevated in lead V3. For occlusion of the left circumflex artery, maximal ST deviation was depressed in lead V2. Occlusion of the right coronary artery caused ST elevation in lead III and ST depression in lead V2. In conclusion, this study demonstrated a significant correlation between summed ST deviation and myocardial ischemia during coronary occlusion that is induced by percutaneous transluminal coronary angioplasty.     

Comparative effects of intracoronary vasodilators on restoring coronary perfusion during flow-reducing coronary stenosis in the dog

The effects of intracoronary injection of nitroglycerin, adenosine, nifedipine and prostacyclin on restoring coronary perfusion during flow-reducing partial coronary obstruction in anesthetized dogs were studied. Coronary obstruction was obtained by inflation of an intraluminal balloon to decrease coronary blood flow and rate of rise in left ventricular pressure (dP/dt) by approximately 30 to 40 and 10%, respectively. Nitroglycerin (0.01 to 10 micrograms/kg per min) increased coronary blood flow and distal coronary pressure and decreased stenosis resistance associated with improved left ventricular dP/dt depending on its dose. In contrast, adenosine (0.3 to 1.0 micrograms/kg per min) decreased coronary blood flow and distal coronary pressure and intensified stenosis resistance associated with depression of left ventricular dP/dt. Nifedipine and prostacyclin caused divergent effects on the coronary circulation related to each dose. Nifedipine (0.01 and 0.1 micrograms/kg per min) and prostacyclin (0.01 micrograms/kg per min) increased coronary blood flow and distal coronary pressure and reduced stenosis resistance. Nifedipine (1.0 micrograms/kg per min) and prostacyclin (0.3 micrograms/kg per min) did not increase coronary blood flow, but reduced distal coronary pressure and intensified stenosis resistance. Thus, the vasodilators produced different effects on restoration of coronary perfusion during pliable severe coronary stenosis. Nitroglycerin and lower doses of nifedipine and prostacyclin improved coronary perfusion due to selective or preferential dilation of large coronary arteries. Adenosine and higher doses of nifedipine and prostacyclin had deleterious effects on the coronary circulation due to potent arteriolar vasodilation.