Hemodynamic and echocardiographic assessment of the effects of diltiazem during transient occlusion of the left anterior descending coronary artery during percutaneous transluminal coronary angioplasty

Treatment of acute right coronary artery occlusion during anesthesia

PURPOSE

Perioperative coronary artery occlusion is a potentially dangerous complication causing myocardial infarction and circulatory collapse. We report a case showing severe ST segment depression in leads II and V5 during anesthesia. Diltiazem and nifedipine, but not nitroglycerine, partially improved the ST changes which were normalized by a percutaneous cardiopulmonary system (PCPS).

CLINICAL FEATURES

A 71-yr-old man with cerebrovascular disease was scheduled for coronary artery bypass grafting (CABG). Past medical history included myocardial infarction due to right coronary artery (RCA) occlusion. Both the femoral artery and vein were cannulated percutaneously before operation and the PCPS was prepared as a back-up system. Depression of the ST segments in leads V5 and II was observed following heparinization. Although hemodynamic stability was maintained with continuous infusion of catecholamines, the ST changes were not improved by intravenous nitroglycerine. Intravenous diltiazem followed by nasal nifedipine partially improved the ST changes. The changes were normalized after induction of PCPS. No neurological complications were observed. The postoperative coronary angiography confirmed the total occlusion of RCA.

CONCLUSION

Calcium channel blockers were more effective than nitroglycerine in treating perioperative ST depression. However, none of them produced complete reversal of the ischemic changes which were normalized with PCPS.

Alteration of left ventricular diastolic function during coronary angioplasty-induced ischemia: a color M-mode Doppler study

OBJECTIVES

The aim of this study was to assess the effects of ischemia on diastolic function by analyzing flow propagation velocity with color M-mode Doppler echocardigraphy.

BACKGROUND

Color M-mode Doppler echocardiography has been proposed as a method of assessing left ventricular filling.

METHODS

Color M-mode Doppler echocardiography and measurement of hemodynamic data were performed simultaneously at baseline and during angioplasty-induced ischemia. Tau was compared with flow propagation velocity. Late diastolic indexes, left ventricular pressure and flow cessation time were also investigated.

RESULTS

During ischemia, left ventricular relaxation rate (tau) increased, whereas flow propagation velocity decreased, from (mean +/- SD) 46.8 +/- 10 ms to 72.6 +/- 18.3 ms and from 59.8 +/- 15.8 cm/s to 30 +/- 8 cm/s, respectively (all p < 0.0001). The maximal slowing of flow propagation velocity was observed 20 to 30 s after the beginning of the inflation, coexisting with a notch on the ascending limb of the negative rate of rise of the left ventricular pressure (dP/dt) curve. Flow propagation velocity was correlated with tau both at baseline (r = 0.53, p < 0.05) and during inflation (r = 0.53, p < 0.03). Left ventricular end-diastolic pressure increased during ischemia from 13.5 +/- 8 mm Hg at baseline to 27.5 +/- 7 mm Hg, while a premature cessation of the entering flow occurred -13.8 +/- 23 ms before the next Q wave onset, compared with 4.5 +/- 19.6 ms after the Q wave onset at baseline (all p < 0.0001).

CONCLUSIONS

The analysis of flow propagation velocity showed that early filling is highly dependent on left ventricular relaxation rate, particularly through the phenomenon of asynchrony. During ischemia, the premature cessation of late filling is associated with increased diastolic pressures.

Identifying and tracking a guide wire in the coronary arteries during angioplasty from X-ray images

During angioplasty, a guide wire (GW) is routinely placed in the coronary artery. Balloon inflation during angioplasty causes transient occlusion of the coronary artery and regional dysfunction. Thus, it is of major importance to monitor myocardial function, which may be impaired during this period. Since the GW moves with the coronary arteries, information regarding myocardial function can potentially be extracted from the GW motion. An algorithm is suggested which is a step toward such monitoring. The algorithm presented is a semiautomatic procedure for identifying and tracking the GW using specific characteristics of the GW. This algorithm is based on working in limited active windows. A preprocessing stage which enhances the GW by the use of a modified Laplacian filter or a modified Marr-Hildreth filter is introduced. The second stage of the algorithm is the tracking of the GW, which is based on fitting a second-degree polynomial to the GW using the Hough transform in each window. To further improve the results further modifications of the basic algorithms that were taken. A single set of parameters, which enabled good tracking for a large number of images taken during angioplasty, was fitted to the final algorithm.

Coronary vein flow velocity changes during transluminal balloon angioplasty: a study using the Doppler guide wire

The coronary flow velocity changes in the great cardiac and middle cardiac veins, induced by intracoronary administration of nitroglycerine, adenosine, and during percutaneous transluminal coronary angioplasty, were evaluated in 12 patients with significant coronary stenoses, using the Doppler wire (Flowire). Optimal spectral signals of the time-averaged peak flow velocity were obtained in 10 patients. Nitroglycerine produced no significant flow velocity changes (P = 0.13). Adenosine caused a significant augmentation of flow velocity compared to baseline (P = 0.003). During balloon inflation, venous flow velocity decreased (P = 0.007); however, the venous outflow did not cease. A pronounced venous hyperemic response, following balloon deflation, was also documented. The utility of continuous vein flow velocity monitoring with the Flowire, during high-risk and complicated coronary interventions remains to be elucidated.

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 equilibration 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 and 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 similarly 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 end-diastolic 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.

Role of calcium channel blockers in reducing acute ischaemia and preventing restenosis in PTCA

Calcium channel blockers (calcium antagonists) are widely used before, during and after percutaneous transluminal coronary angioplasty (PTCA). When administered during PTCA, calcium channel blockers may be beneficial in decreasing regional ischaemia in patients with proven or suspected variant angina, as a result of their cardioprotective effects, their ability to enhance collateral flow, and their antispastic effects at the epicardial level. More recently, the agents have also proven to be effective in patients who have developed "no-reflow' phenomenon during PTCA. Preliminary findings suggest that calcium channel blockers may also have potential benefits when administered after angioplasty. The combined results of 5 studies, evaluating a total of 919 patients, showed a trend towards angiographic reduction in restenosis. These observations are of interest but may be due to reporting bias. In conclusion, calcium channel blockers are effective in reducing ischaemia induced by PTCA. These agents may, thus, be appropriate in high risk patients. Further large studies examining the effects of calcium channel blockers on restenosis are required to confirm the observations available to date.

Clinical effects and utility of intracoronary diltiazem

Coronary artery spasm is a known complication of coronary interventions, for which intracoronary nitroglycerin (ICN) is the treatment of choice. Some forms of intense spasm are resistant to ICN. Calcium channel antagonists are also known to be effective for coronary artery spasm, including nitroglycerin-resistant spasm. Here we describe a protocol for the clinical use of intracoronary diltiazem (ICD). By this protocol, ICD can be safely given without disturbing the clinical status of patients. ICD (2.5 mg) given slowly over 1 minute produced no vasodilitation of normal vessel segments but did produce significant dilatation of stenotic segments above and beyond the effects of nitrates. Mean minimum lumen diameter increased 18%, from 0.89 +/- 0.06 mm to 1.06 +/- 0.07 mm (mean +/- SEM, P < 0.001). ICD produced clinically insignificant changes in systolic blood pressure, diastolic blood pressure, heart rate, and PR, QRS, and QT intervals. This protocol has been employed to safely use ICD to relieve both nitroglycerin-resistant epicardial artery spasm and nitroglycerin-resistant distal microvascular spasm (the no-reflow phenomenon).

Effects of acute, transient coronary occlusion on global and regional right ventricular function in humans

OBJECTIVES

The aim of this study was to investigate the changes in right ventricular function during acute coronary occlusion produced by inflating a coronary angioplasty balloon catheter.

BACKGROUND

Alterations in right ventricular function are well known to occur in patients with acute myocardial infarction or ischemic cardiomyopathy. However, the changes in right ventricular function resulting from acute, transient coronary occlusion of each of the major coronary arteries have been scantily studied, perhaps because of serious limitations of currently available technology.

METHODS

A newly designed, mobile, multiwire gamma camera, in combination with generator-produced tantalum-178, affords high count rate first-pass radionuclide angiography and is thus ideal for studying right ventricular function at the bedside. Accordingly, 46 patients underwent first-pass radionuclide angiography at baseline and during transient coronary occlusion induced by a coronary angioplasty balloon catheter.

RESULTS

A significant, albeit modest, decrease in global right ventricular ejection fraction occurred during occlusion of the left anterior descending (from 42.9 +/- 9.3% to 39 +/- 8.7%, p < 0.05) and left circumflex (from 44 +/- 9.1% to 38.8 +/- 7.9%, p = 0.03) coronary arteries, but diagonal artery occlusion caused no significant change in right ventricular ejection fraction. Occlusion of the right coronary artery proximal (but not distal) to the acute marginal branch caused a significant decrease in right ventricular ejection fraction (from 42.6 +/- 4.7% to 35.7 +/- 7.2%, p < 0.01). Although occlusion of the left anterior descending, left circumflex and proximal right coronary arteries all caused significant deterioration in regional right ventricular function, only proximal right coronary occlusion caused right ventricular dilation (p < 0.005).

CONCLUSIONS

Significant impairment of right ventricular function occurs during transient occlusion of the left anterior descending, left circumflex and proximal right coronary arteries, but only occlusion of the latter causes acute right ventricular dilation, probably as a result of ischemia.

Use of intracoronary ultrasonography in assessing pharmacotherapy for myocardial ischemia

Intracoronary ultrasonography can provide morphologic and physiologic information on coronary vasomotor responses to pharmacotherapy. Preliminary studies indicate a high correlation between dimensions determined by 2-dimensional echocardiography, angiography, and pathology. Similarly, the emerging data on intracoronary Doppler flow velocity responses beyond atherosclerotic obstructions before, during, and after coronary balloon occlusion will provide further insights into myocardial oxygen supply and its responses to pharmacotherapy during controlled myocardial ischemia.

Quantification of left ventricular performance during transient coronary occlusion at various anatomic sites in humans: a study using tantalum-178 and a multiwire gamma camera

To study the functional significance of transient coronary occlusion on systolic and diastolic left ventricular function relative to the anatomic site of occlusion, first-pass radionuclide angiography with a mobile multiwire gamma camera using tantalum-178 (dose activity less than or equal to 84 mCi/elution) was performed in 46 patients undergoing balloon coronary angioplasty. First-pass images were acquired immediately before angioplasty and during the last 30 s of a 60-s balloon inflation in 23 left anterior descending arteries, 18 right coronary arteries, 8 circumflex arteries and 3 diagonal coronary arteries. Occlusion of the left anterior descending artery resulted in significant decreases in left ventricular ejection fraction (54.6 +/- 12.7% to 32.3 +/- 10.6%, p = 0.0001) and peak filling rate (2.48 +/- 0.68 to 1.75 +/- 0.64 end-diastolic volumes/s, p = 0.0001), accompanied by severe abnormalities in regional function and left ventricular dilation. Right coronary artery occlusion caused inferior hypokinesia, but did not significantly change left ventricular ejection fraction (48.5 +/- 12.4% vs. 45.8 +/- 12.5%, p = NS) or peak filling rate (2.05 +/- 0.81 vs. 2.09 +/- 0.81 end-diastolic volumes/s, p = NS). Circumflex artery occlusion resulted in mild wall motion deterioration and a borderline decrease in ejection fraction (54.7 +/- 11.4% to 50.5 +/- 12%, p = 0.057). Diagonal artery occlusion did not cause significant changes in left ventricular ejection fraction or filling rate. The decrease in left ventricular ejection fraction during coronary occlusion was 9 +/- 25% and 27 +/- 22%, respectively, in those arteries with and without collateral supply (p = 0.052). These data provide strong evidence for the critical importance of the left anterior descending artery and the secondary role of the other coronary arteries in maintaining global systolic and diastolic left ventricular function and suggest a protective role of collateral vessels during coronary occlusion.

Attenuation of myocardial ischemia during coronary occlusion by ultrashort-acting beta adrenergic blockade

To assess the effect of the ultrashort-acting beta blocker esmolol on ischemia induced by acute coronary occlusion, we studied 16 patients undergoing coronary angioplasty. Doppler echocardiography and ECG monitoring were performed continuously before, during, and after balloon occlusion in the drug-free state and during esmolol infusion. Fourteen of the 16 patients had ST segment elevation during balloon inflation. However, maximal ST segment elevation (2.1 +/- 1.5 mm vs 1.7 +/- 1.3 mm, p less than 0.001) and duration of ST segment elevation (68 +/- 20 seconds vs 54 +/- 19 seconds, p less than 0.05) were both significantly reduced during esmolol infusion. Furthermore, the decrease in ejection fraction seen during drug-free balloon occlusions was significantly blunted during esmolol infusion. In the baseline state ejection fraction decreased from 55% to 38% (p less than 0.05) during coronary occlusion compared with a decrease from 52% to 49% (p = NS) during esmolol infusion. In addition, esmolol appeared to delay the onset of segmental wall motion abnormalities after coronary occlusion, occurring at a mean of 40 seconds after balloon inflation versus a mean of 31 seconds in the absence of beta blockade (p less than 0.05). Thus the use of ultrashort-acting beta blockade appears to diminish the extent and delay the onset of myocardial ischemia during acute coronary occlusion.

Effect of gallopamil on myocardial ischaemia during percutaneous transluminal coronary angioplasty

This report summarises selected preliminary results from an ongoing study designed to investigate the effect of the calcium antagonist gallopamil on myocardial ischaemia during percutaneous transluminal coronary angioplasty (PTCA). To date, 12 adult males with coronary artery disease and significant proximal stenosis of the left anterior descending coronary artery (LAD) have been randomly assigned to gallopamil or placebo under double-blind conditions. Patients with recent myocardial infarction, apparent collateralisation of the LAD, myocardial failure, sinoatrial or atrioventricular block, severe hepatic disease or renal failure were excluded from the study. PTCA was performed using at least 2 balloon inflations, each of 2 minutes' duration. Gallopamil 0.4 mg or placebo (normal saline) were administered during the 10-minute interval between the 2 inflations. Blood samples were taken simultaneously from the coronary sinus and the femoral artery before and immediately after each inflation. Lactate concentration and the relative amount of activated neutrophils were selected for trend analysis. Furthermore, ECG changes were analysed by calculating the sum of the absolute ST-segment deviations (80 msec after J point, maximal T deviation) of leads I, II, III, V2, V4 and V6. In the presence of gallopamil, the degree of ST-segment/T-wave changes induced by balloon inflation was reduced. Additionally, gallopamil attenuated myocardial lactate release and appeared to prevent the increase in activated neutrophils observed during control inflations. These preliminary results suggest a beneficial effect from intracoronary administration of gallopamil during PTCA, achieved by attenuation of the ischaemic reaction during coronary occlusion.

Myocardial protection by intravenous diltiazem during angioplasty of single-vessel coronary artery disease

The possible cardioprotective effect of diltiazem during ischemia caused by percutaneous transluminal coronary angioplasty was tested. Electrocardiograms and myocardial lactate, hypoxanthine and urate production were determined in 26 patients with a stenosis in the left anterior descending artery without angiographically demonstrable collaterals. Measurements took place before angioplasty, after each of 4 occlusions and 15 minutes after the last balloon inflation. Patients were randomly given placebo or DL-diltiazem (0.4 mg/kg as a bolus intravenously, followed by an infusion of 15 mg/hr). During angioplasty the ST-segment elevation for the anterior wall leads V2, V4 and V6, and the intracoronary lead was similar for both groups, as was lactate release. Diltiazem significantly reduced cardiac hypoxanthine release immediately after angioplasty from 63 to 88% (p less than 0.05). The drug diminished urate production after the last dilatation by 82% (p less than 0.05). In conclusion, intravenous infusion of diltiazem reduced cardiac adenosine triphosphate breakdown during angioplasty as shown by diminished hypoxanthine and urate production. In contrast, diltiazem was unable to attenuate ST-segment elevation and lactate release.

Impaired relationship between Doppler echocardiographic parameters of diastolic function and left ventricular filling pressure during acute ischemia

The relationship between left ventricular filling pressure and Doppler echocardiographic parameters of diastolic mitral flow (MF) was evaluated in patients with ischemic heart disease during acute ischemia induced by percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending artery. Thirty-two patients were examined by simultaneous recordings of the Doppler MF signal and the mean pulmonary capillary wedge pressure (PCm) as an approximation of left ventricular filling pressure. At rest PCm was correlated with the early/late velocity integral ratio (Ei/Ai: r = 0.62: p less than 0.0001; n = 32). In 25 of 32 patients the recordings during PTCA could be evaluated. At the end of the inflation (duration: 69 +/- 24 seconds) PCm increased from 11.2 +/- 5.5 to 17.2 +/- 7.2 mm Hg (p less than 0.001), and total MF integral as an index of systolic ventricular function decreased by 14.9 +/- 12.8% (p less than 0.001). Inasmuch as both early and late velocity integrals were reduced during PTCA, the Ei/Ai ratio did not change significantly (1.41 +/- 0.51 to 1.34 +/- 0.60; NS). In a subgroup of inflations without ECG signs of ischemia, Ei was decreased without a concomitant decrease in Ai, thus leading to a decrease in the Ei/Ai ratio (1.36 +/- 0.43 to 1.17 +/- 0.31; p less than 0.05). Summarizing the events during PTCA, a steady increase in PCm was observed, whereas the Ei/Ai ratio was slightly decreased. Thus the observation at rest that an elevated PCm was associated with an elevated Ei/Ai was no longer valid during PTCA (Ei/Ai: r = 0.28; NS). A significant correlation was found between parameters of Doppler MF and PCm in patients with ischemic heart disease at rest. During PTCA this relationship was attenuated. Therefore noninvasive assessment of left ventricular filling pressures during acute ischemia by Doppler echocardiography does not seem feasible.

Effects of diltiazem and nifedipine on systemic and coronary hemodynamics and ischemic responses during transient coronary artery occlusion in patients

Diltiazem and nifedipine improve coronary blood flow and reduce peripheral determinants of myocardial oxygen demand through activation of similar but distinct cellular mechanisms. To identify differences during myocardial ischemia, systemic and coronary hemodynamics were measured continuously before and during brief periods of left anterior descending coronary balloon occlusion in 23 patients undergoing single-vessel angioplasty. Data were compared for two matched ischemic periods, one control and one "drug" period. In 13 patients, diltiazem, 10 mg (intravenous bolus with continuous 500 mg/min infusion), was given; in 10 patients, nifedipine, 10 mg sublingual, was given and after 15 minutes, ischemia was reinduced. Both drugs significantly reduced systolic and mean arterial pressure (for diltiazem, 108 +/- 15 to 93 +/- 10 mm Hg; and for nifedipine, 117 +/- 20 to 96 +/- 8 mm Hg, both p less than 0.01). Diltiazem significantly reduced heart rate-pressure product (with heart rate unchanged), while both drugs maintained the resting great vein blood flow (for diltiazem, 97 +/- 25 to 91 +/- 34 ml/min; for nifedipine, 115 +/- 49 to 98 +/- 58 ml/min, p = ns) with reduced arterial pressure. Coronary flow during occlusion was unchanged (for control versus diltiazem, 63 +/- 21 versus 59 +/- 14 ml/min; for nifedipine, 66 +/- 33 versus 73 +/- 38 ml/min, both p = ns). Neither drug improved collateral hemodynamics or resistance index during ischemia. Both diltiazem and nifedipine prolonged the time to ischemic ST segment alteration (for diltiazem, 27 +/- 10 to 40 +/- 16 seconds, p less than 0.05; for nifedipine, 24 +/- 14 to 38 +/- 14 seconds, p = ns) during transient coronary occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)