New electrocardiographic criteria for predicting the site of coronary artery occlusion in inferior wall acute myocardial infarction

In patients with inferior wall acute myocardial infarction (AMI), the site of the culprit lesion is an important determinant of outcome. Patients with right ventricular infarction have a poor prognosis, whereas those with occlusion of the left circumflex coronary artery (LCx) have a good prognosis. Therefore, we assessed whether standard 12-lead electrocardiograms obtained on admission could identify the site of coronary artery occlusion, (i.e., a site proximal to the origin of the right ventricular branch of the right coronary artery [RCA], a site distal to the origin of the right ventricular branch of the RCA, or a site in the LCx). The ratio of ST depression in lead V3 to ST elevation in lead III (V3/III ratio) was evaluated immediately before coronary angiography in 152 patients with a first inferior wall AMI confirmed by coronary angiography within 12 hours after the onset of symptoms. For occlusion of the proximal RCA, distal RCA, and LCx, V3/III ratio was 0.2+/-0.3, 0.8+/-0.5, and 2.5+/-2.5 (p = 0.0001), respectively. The V3/III ratio <0.5 identified proximal RCA occlusion, 0.5 相似文献   

In-hospital outcome of elderly patients with acute inferior myocardial infarction and right ventricular involvement

BACKGROUND: There are some specific high-risk subgroups of patients with acute inferior myocardial infarction, such as older patients and those with right ventricular involvement. However, the clinical implications of right ventricular infarction in elderly subjects have not been studied previously. METHODS AND RESULTS: To determine the clinical impact of right ventricular involvement in elderly patients with inferior myocardial infarction, we studied the in-hospital outcome of 198 consecutive patients > or = 75 years of age with a first acute inferior myocardial infarction according to the presence of ECG or echocardiographic criteria of right ventricular infarction. In patients with right ventricular involvement (41%), in-hospital case fatality rate was 47% (mainly because of nonreversible low cardiac output cardiogenic shock) compared with 10% in patients without right ventricular involvement (P<.001). Patients with right ventricular involvement also had a significantly higher incidence of cardiogenic shock (32% versus 5%), which was independent of left ventricular ejection fraction, complete AV block (33% versus 9%), and interventricular septal rupture (9% versus 0%). After adjustment for age, sex, diabetes, shock on admission, left ventricular systolic dysfunction, and complete AV block, right ventricular infarction remained a powerful independent predictor of in-hospital death (adjusted odds ratio, 4.0; 95% confidence interval, 1.3 to 14.2). CONCLUSIONS: Elderly patients with acute inferior myocardial infarction have a substantially increased risk of death during hospitalization when right ventricular involvement is present. The poorer outcome is due mainly to the high incidence of cardiogenic shock and its infrequent reversibility.     

The relationship between the electrocardiographic pattern with TIMI flow class and ejection fraction in patients with a first acute anterior wall myocardial infarction

AIMS: The aim of this study was to assess the value of the electrocardiogram in predicting the patency of the left anterior descending artery and left ventricular ejection fraction in patients with a first acute anterior wall myocardial infarction at discharge from the coronary care unit. METHOD: We included 116 consecutive patients with an acute anterior myocardial infarction who had undergone coronary angiography and left ventriculography before discharge from the coronary care unit (7th to 10th day). The ST segment, either elevated or isoelectric (< 1 mm), and the T wave (positive or negative) in precordial leads V2-V4 were analysed and compared to the TIMI flow from each patient. RESULTS: Out of 69 patients with negative T waves, 38 (55%) had TIMI flow 3 compared with 20 (29%) and 11 (16%) with TIMI flow 2 and 0-1, respectively; and out of 47 patients with positive T waves seven (15%) had TIMI flow 3, 17 (36%) TIMI flow 2 and 23 (49%) TIMI flow 0-1 (P < 0.001). Out of 63 patients with an isoelectric ST segment, 35 (55%) had TIMI flow 3, 18 (29%) TIMI flow 2 and 10 (16%) TIMI flow 0-1, and out of 53 with ST segment elevation, 10 (19%) had TIMI flow 3, 19 (36%) TIMI flow 2 and 24 (45%) TIMI flow 0-1 (P < 0.001). When both parameters were analysed together, we found that in 46 patients with both isoelectric ST segments and negative T waves, 30 (65%) had TIMI flow 3 compared with two of 30 (7%) patients with ST segment elevation and positive T waves (P < 0.001). Patients with isoelectric ST segments had a better degree of left ventricular ejection fraction (57.8 +/- 14.1%) than patients with ST segment elevation (41.7 +/- 13%) (P < 0.001). Patients with positive and negative T waves had a similar left ventricular ejection fraction (49 +/- 18.1% vs 51 +/- 14%). CONCLUSION: We concluded that patients with a first acute anterior myocardial infarction and an electrocardiogram pattern of an isoelectric ST segment and a negative T wave have a higher incidence of a patent left anterior descending coronary artery than similar patients with ST segment elevation and a positive T wave. An isoelectric ST segment is also related to better left ventricular function.     

Inferior ST segment depression as a useful marker for identifying proximal left anterior descending artery occlusion during acute anterior myocardial infarction

To determine whether or not ST segment deviation on admission electrocardiograms can identify patients with anterior acute myocardial infarction due to proximal left anterior descending artery occlusion, the magnitude and location of ST segment elevation or depression were compared between patients with proximal left anterior descending artery occlusion (group A, n = 47) and those with distal left anterior descending artery occlusion (group B, n = 59). ST segment depression in each of the inferior leads was significantly greater in group A than in group B. The incidence of ST segment depression > or = 1 mm in each of the inferior leads (II; 81% vs 27%, III; 85% vs 54%, aVF; 87% vs 47%, P < 0.01) was significantly higher in group A than in group B. In addition, the incidence of ST segment depression > or = 1 mm in all of the inferior leads was significantly greater in group A than in group B (77% vs 22%, P < 0.01). In group A, maximal ST segment elevation was more frequent in lead V2 alone (43% vs 14%, P < 0.01). Group A had greater ST segment elevation in lead aVL than group B, and the incidence of ST segment elevation > or = 1 mm in lead aVL was significantly higher in group A than in group B (66% vs 47%, P < 0.05). ST segment depression > or = 1 mm in all of the inferior leads was most valuable for identifying group A patients (77% sensitivity and 78% specificity). In contrast, the maximal ST segment elevation in lead V2 alone or ST segment elevation > or = 1 mm in lead aVL had a low diagnostic value (43% sensitivity and 86% specificity, 66% sensitivity and 53% specificity, respectively). In conclusion, this study indicates that analysis of ST segment deviation in the inferior leads is useful for identifying patients with acute anterior myocardial infarction due to proximal left anterior descending occlusion.     

Effect of reperfusion on biventricular function and survival after right ventricular infarction

BACKGROUND: Although the salutary effects of reperfusion in patients with left ventricular infarction are well documented, the benefits in patients with acute right ventricular infarction are less clear. METHODS: To determine whether primary angioplasty improves right ventricular function and the clinical outcome in patients with right ventricular infarction, we performed echocardiographic studies before and after angioplasty in 53 patients with acute right ventricular infarction. RESULTS: Complete reperfusion, defined as normal flow in the right main coronary artery and its major right ventricular branches, was achieved in 41 patients (77 percent), leading to prompt and striking recovery of right ventricular function (mean [+/-SE] score for free-wall motion, 3.0+/-0.1 at base line and 1.4+/-0.1 at three days; P<0.001). Twelve patients (23 percent) had unsuccessful reperfusion, defined as the failure to restore right ventricular branch flow, with or without patency of the right main coronary artery. Unsuccessful reperfusion was associated with lack of recovery of right ventricular function (score for free-wall motion, 3.2+/-0.2 at base line and 3.0+/-0.9 at three days; P= 0.55), as well as persistent hypotension and low cardiac output (in 83 percent of the patients, vs. 12 percent of those with successful reperfusion; P=0.002) and a high mortality rate (58 percent, vs. 2 percent for those with successful reperfusion; P=0.001). CONCLUSIONS: In patients with right ventricular infarction, complete reperfusion of the right coronary artery by angioplasty results in the dramatic recovery of right ventricular performance and an excellent clinical outcome. In contrast, unsuccessful reperfusion is associated with impaired recovery of right ventricular function, persistent hemodynamic compromise, and a high mortality rate.     

Use of changes in ST segment elevation for prediction of infarct artery recanalization in acute myocardial infarction

BACKGROUND: The role of the ECG in evaluating reperfusion status after thrombolytic treatment in acute myocardial infarction is not clear. Dramatic ST segment changes have been observed during recanalization of an infarct-related artery, but ST criteria have not been definitively established for prediction of coronary artery patency. Differences in ST segment changes in relation to infarct localization have not been evaluated, and further investigation is required into reciprocal ST depression, which provides information independent from ST elevation. Therefore, the aim of this study was to evaluate how early changes in ST segment elevations and depressions predict vessel patency after fibrinolysis for patients with anterior and inferior/lateral infarcts. METHODS AND RESULTS: Two hundred patients with a Pardee wave in the ECG and chest pain of less than 6 h duration were given thrombolytic treatment. The result of the therapy was assessed simultaneously with coronary angiography. Patients were divided into two groups: I (50 patients) without recanalization (TIMI grade 0, 1 or 2), and II (150 patients) with successful recanalization (TIMI grade 3). Before and after therapy, analysis of the 12 lead ECG included maximum ST elevation measurement (H1, H2 respectively), the sum of ST elevations (sigma H1, sigma H2), the sum of ST segment depressions (sigma h1, sigma h2), and the ratios of ST segment changes (R1 = H2:H1, R2 = sigma H2:sigma H1, R3 = sigma h2:sigma h1). The mean interval from the first to the second ECG was 3.5 +/- 1 h. Successive values of R1 and R2 were examined to find that which best distinguished between the two groups. The best values for prediction of reperfusion were: (1) For anterior wall infarct [table: see text] (2) For inferior and lateral infarct [table: see text] In 13 patients with a complete right or left bundle branch block in the first or second ECG, the result of treatment was predicted in 11 patients using criteria for factor R1 and in 12 patients using criteria for R2. Analysis of ST segment depressions revealed a significant correlation between normalization of ST segment depressions and elevations (R3 vs R1: r = 0.60, P < 0.05; R3 vs R2 r = 0.59, P < 0.05). Multivariate discriminant analysis showed an independent value of R3 for discrimination between the two groups, but only in patients with inferior/lateral infarcts. The overall accuracy of the common algorithm in predicting reperfusion was significantly better in patients with inferior/lateral infarcts (Chi2 test, P = 0.0078). When separate algorithms were used, there was no significant difference between patients with anterior or inferior/lateral infarcts because of the significant improvement in prediction of reperfusion in patients with anterior infarcts (McNemar's test: P = 0.041). CONCLUSIONS: We conclude that analysis of ST segments on the standard 12-lead ECG offers valuable help in the early identification of successful recanalization of infarct-related arteries after thrombolytic therapy in patients with acute myocardial infarction. Use of the ratio of ST segment normalization according to the separate criteria for anterior and inferior/lateral infarcts gives the test a high sensitivity and specificity, even in the presence of interventricular conduction disturbances.     

Impaired regional fatty acid uptake and systolic dysfunction in hypertrophied right ventricle

Little information is available regarding the determinants of systolic contractile function of the hypertrophied right ventricle (RV). The purpose of this study was to clarify the relationship between myocardial metabolism and contractile function in the hypertrophied RV due to pulmonary hypertension (PH). METHODS: Iodine-123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and 99mTc-sestamibi (MIBI) SPECT were performed to calculate the RV-to-left ventricle (LV) tracer uptake ratio (RV/LV) in 21 patients with PH (6 with primary PH and 15 with chronic thromboembolic PH). The patients also underwent electron-beam CT to assess RV ejection function (RVEF) and percentage systolic wall thickening (%SWT) and right heart catheterization to measure mean pulmonary arterial pressure (mPAP). RESULTS: There were significant positive correlations between mPAP and MIBI-RV/LV (r = 0.89, p < 0.001) and between mPAP and BMIPP-RV/LV (r = 0.86, p < 0.001). However, 8 patients showed lower BMIPP-RV/LV than MIBI-RV/LV, indicating the impairment of myocardial fatty acid uptake in the RV. These patients had lower RVEF and %SWT compared to those with normal myocardial fatty acid uptake (RVEF = 28% +/- 10% compared to 40% +/- 9% and %SWT = 33% +/- 27% compared to 74% +/- 30%, respectively; p < 0.05 for both comparisons). Although mPAP did not differ between the groups, the RVEF-mPAP and %SWT-mPAP regression lines drawn from the patients with impaired myocardial fatty acid uptake were located below the lines from the patients with normal myocardial fatty acid uptake, suggesting disproportionately decreased RV myocardial contractility for a given mPAP in patients with impaired myocardial fatty acid uptake. The patients with the impaired fatty acid uptake in the RV had a significantly higher death rate (log-rank test, p < 0.05). CONCLUSION: The results from this preliminary study suggest that myocardial fatty acid uptake is impaired in the failing hypertrophied RV due to PH.     

Exercise-induced T-wave normalization predicts recovery of regional contractile function after anterior myocardial infarction

AIMS: We investigated the ability of T-wave pseudonormalization and ST-segment elevation, which are demonstrated in infarct-related leads during submaximal exercise testing, to predict late recovery of contractile function. METHODS: We studied 88 consecutive patients (73 males, mean age 59 +/- 8 years) with anterior infarction, persistent T-wave inversion and a documented lesion of the proximal segment of the left anterior descending coronary artery. They all underwent 2D-echocardiography on admission, 4 weeks as well as 6 months after myocardial infarction to evaluate the dysfunction score and the ejection fraction. Submaximal (75% of maximal predicted heart rate) exercise testing was performed in 80 patients 2 weeks after myocardial infarction following discontinuation of treatment. RESULTS: During exercise testing, 59 of the 88 patients showing negative T-waves on the resting electrocardiogram exhibited pseudonormalization (group A) in at least three adjacent precordial leads, whilst 29 (group B) did not. Patients of group A more frequently exhibited an early creatine kinase peak (41% vs 24%, P < 0.05) and residual angiographic perfusion (97% vs 69%, P < 0.05). The dysfunction score did not change in group B (from 19 +/- 7 to 22 +/- 4), but decreased in group A (from 18 +/- 4 to 11 +/- 6 P < 0.05). The ejection fraction was similar in the two groups on admission (group A: 48 +/- 7%, group B: 45 +/- 10%), but was significantly different at 4-week (52 +/- 99 vs 42 +/- 11%, P < 0.05) and 6-month follow-up (58 +/- 9 vs 44 +/- 10%, P < 0.01). The concomitant presence of ST-segment elevation and T-wave normalization showed the highest positive predictive value for left ventricular function recovery (100%). CONCLUSIONS: T-wave normalization induced by submaximal exercise test is frequently associated with residual perfusion to the infarct area and predicts progressive improvement in regional wall motion, especially if associated with ST-segment elevation. Therefore, these electrocardiographic findings may be used as easily obtainable markers of residual viability that predict late recovery in contractile function.     

Randomized trial of direct coronary angioplasty versus intravenous streptokinase in acute myocardial infarction

OBJECTIVES: The objective of this study was to obtain preliminary data on the relative clinical utility of direct coronary angioplasty compared with that of intravenous thrombolytic therapy for patients with acute myocardial infarction. BACKGROUND: The relative merits of intravenous thrombolytic therapy and direct coronary angioplasty as treatment for acute myocardial infarction are incompletely understood, and randomized trials of these treatments have been extremely limited. METHODS: One hundred patients with ST segment elevation presenting to a single high volume interventional center within 6 h of the onset of chest pain were randomized to receive either streptokinase (1.2 million U intravenously over 1 h) or immediate catheterization and direct coronary angioplasty. Patients were excluded for age > or = 75 years, prior bypass surgery, Q wave infarction in the region of ischemia or excessive risk of bleeding. All patients were then treated with aspirin (325 mg orally/day) and heparin (1,000 U intravenously/h) for 48 h until catheterization was performed to determine the primary study end point, namely, infarct-related artery patency at 48 h. Secondary end points were in-hospital death, left ventricular ejection fraction at 48 h and time to treatment. RESULTS: There was no difference in the baseline characteristics of the two treatment groups. Overall patient age was 56 +/- 10 years, 83% of patients were male, 11% had prior infarction, 40% had anterior infarction and 97% were in Killip class I or II. Although time to treatment was delayed in the angioplasty group (238 +/- 112 vs. 179 +/- 98 min, p = 0.005), there was no difference in 48-h infarct-related artery patency or left ventricular ejection fraction (patency 74% vs. 80%; ejection fraction 59 +/- 13% vs. 57 +/- 13%; angioplasty vs. streptokinase, p = NS for both). There were no major bleeding events, and the mortality rate with angioplasty (6%) and streptokinase (2%) did not differ (p = NS). CONCLUSIONS: These results suggest that intravenous thrombolytic therapy might be preferred over coronary angioplasty for most patients because of the often shorter time to treatment.     

Incidence of right ventricular asynergy in patients with coronary artery disease

The effects of coronary artery disease on patterns of left ventricular contractility have been thoroughly investigated. In contrast, little is known about the incidence of right ventricular dysfunction induced by this disease. To evaluate the frequency of right ventricular asynergy, biplane right ventricular cineangiograms were obtained in 26 patients. Seven segmental axes of shortening were analyzed in each end-systolic and end-diastolic frame and normalized as percent decrease (or increase) in axis from end-diastolic length. Of 26 patients, 8 (Group I) served as normal (control) subjects. The remaining 18 patients had significant coronary artery disease; 6 of these (Group II) had no significant disease of the right coronary artery, whereas 12 (Group III) had significant obstruction of this artery. Four patients in Group II had a previous anteroseptal myocardial infarction, and six in Group III had a previous inferior myocardial infarction. There was a progressive decrease in segmental axes of shortening from Group I to II and from Group II to II, but the decrease was not significant at the level P less than 0.01. Only one patient in Group II had frank dyskinetic segmental motion of the interventricular septum (this patient had had a previous anteroseptal myocardial infarction), whereas two patients in Group III had dyskinetic segmental motion of the free right ventricular wall (both had previous inferior myocardial infarction). Therefore, coronary artery disease seldom produces significant right ventricular asynergy. Abnormal septal motion is associated with previous anteroseptal myocardial infarction; however, dyskinetic motion of the free right ventricular wall occurs only in patients with a right coronary arterial lesion and previous inferior myocardial infarction.     

Coronary recanalization by elective angioplasty prevents ventricular dilation after anterior myocardial infarction

OBJECTIVES: In a prospective study we evaluated whether late recanalization of the left anterior descending coronary artery (LAD) affects ventricular volume and function after anterior myocardial infarction. BACKGROUND: Persistent coronary occlusion after anterior myocardial infarction leads to ventricular dilation and heart failure. METHODS: We studied 73 consecutive patients with acute anterior myocardial infarction as a first cardiac event; all had an isolated lesion or occlusion of the proximal LAD. Six patients died before hospital discharge. The 67 survivors were classified into two groups: group I (patent LAD and good distal flow, n = 40) and group II (LAD occlusion or subocclusion, n = 27). The 20 patients in group I who had significant residual stenosis and all patients in group II underwent elective percutaneous transluminal coronary angioplasty (PTCA) within 18 days of myocardial infarction. The procedure was successful in 17 patients in group I (group IB) and in 16 patients in group II (group IIA): in the remaining 11 patients of group II, patency could not be reestablished (group IIB). Left ventricular volumes, ejection fraction and a dysfunction score were measured by echocardiography on admission, before PTCA, at discharge and after 3 and 6 months. RESULTS: Although cumulative ST segment elevation was similar in groups I and II, ejection fraction and dysfunction score were significantly worse in group II. However, ventricular function and volumes progressively improved in group IIA, whereas group IIB exhibited progressive deterioration of function (dysfunction score [mean +/- SD] increased from 21 +/- 6 to 25 +/- 8, p < 0.05; ejection fraction decreased from 43 +/- 10% to 37 +/- 11%, p < 0.05); and end-systolic volume increased from 34 +/- 10 to 72 +/- 28 ml/m2, p < 0.05). Patients in group IIB also had worse effort tolerance, higher heart rate at rest, lower blood pressure and significantly greater prevalence of chronic heart failure. CONCLUSIONS: Delayed PTCA of an occluded LAD can frequently restore vessel patency. Success appears to be associated with better ventricular function and a lack of chronic dilation. Large randomized studies are warranted to evaluate the effect of delayed PTCA on late mortality.     

The biochemical inhibition mode of bredinin-5''-monophosphate on DNA polymerase beta

PURPOSE: To determine electrocardiographic features associated with myocardial salvage following reperfusion therapy in patients with inferior myocardial infarction. PATIENTS AND METHODS: Ninety-two consecutive patients with acute inferior myocardial infarction were treated with reperfusion therapy in a tertiary care center. Several features were measured on the presenting electrocardiogram, including the presence or absence of ST depression in the chest leads and the total magnitudes of ST elevation or depression, and were then evaluated for their association with myocardial salvage. Myocardial salvage (% of left ventricle) was the difference between myocardium at risk and final infarct size. Tomographic myocardial perfusion imaging with technetium-99m sestamibi was performed acutely to measure myocardium at risk and repeated prior to hospital discharge to measure final infarct size. RESULTS: The amount of myocardium at risk of infarction in the 92 patients was 19.1%+/-11.3% (range 1% to 68%), and the final infarct size was 10.6%+/-10.0% (range 0% to 45%). Thus, myocardial salvage in the 92 patients was 8.5%+/-8.4% (range -11% to 35%) of the left ventricle, or 0.51+/-0.38 (range 0.0 to 1.0) when expressed as a fraction of the myocardium at risk (salvage index). The presence or absence of anterior ST depression was the only one of seven electrocardiographic variables that was associated with myocardial salvage. Myocardial salvage was significantly greater in patients with anterior ST depression compared with those without it (10.6%+/-9.0% versus 5.9%+/-6.7%, P=0.025). Myocardium at risk was significantly greater in patients with anterior ST depression compared with those without the depression (22.8%+/-12.2% versus 14.6%+/-8.3%, P=0.0006), and infarct size tended to be larger (12.1%+/-10.4% versus 8.7%+/-9.4%, P=0.10). Myocardial salvage as a fraction of the myocardium at risk (salvage index) was similar between the two patient groups (0.52+/-0.37 versus 0.50+/-0.39, P=NS). CONCLUSION: The presence of anterior ST depression during inferior myocardial infarction identifies a group of patients with the potential for greater myocardial salvage with reperfusion therapy. Such patients derive greater absolute benefit from reperfusion therapy because they have a larger amount of myocardium at risk, although their response to therapy (salvage index) is not intrinsically different.     

Effects of norepinephrine on right ventricular function in septic shock patients

OBJECTIVE: To study the effects of norepinephrine on right ventricular function in patients with hyperdynamic septic shock. DESIGN: Prospective, open study. SETTING: A 15 bed ICU in a university hospital. PATIENTS: 9 patients with hyperdynamic septic shock (SBP < 90 mmHg, Cl > or = 4 l.min-1.m-2, SVRI < or = 850 dynes.s.cm-5m-2 and oliguria). INTERVENTIONS: Plasma volume expansion was used to correct a suspected volume deficit and then, norepinephrine infusion was started and titrated to restore systemic blood pressure to the normal range (mean infusion rate: 1.1 +/- 0.2 mcg.kg-1.min-1). Norepinephrine was the only vasoactive agent used in these patients. MEASUREMENTS AND RESULTS: A modified Swan-Ganz catheter mounted with a fast response thermistor was inserted in each patient, allowing repeated measurements of RVEDVI and RVEF. At time of inclusion to the study, all but one patient had elevated MPAP (23 +/- 4 mmHg) and RVEF < or = 50%, and all patients had RVEDVI > or = 90 ml.m-2. During norepinephrine infusion, MAP increased from 51 +/- 9 to 89 +/- 10 mmHg (p < 0.0001), PVRI increased from 204 +/- 35 to 286 +/- 63 dynes.s.cm-5.m-2 (p < 0.05), and despite this increase in right ventricular afterload, no detrimental effect in RVEF (36 +/- 11 to 36 +/- 10%) or in RVEDVI (116 +/- 30 to 127 +/- 40 ml.m-2) was observed. A Frank-Starling relationship for the right ventricle was constructed by plotting an index of ventricular performance (RVSWI) against an index of ventricular preload (RVEDVI). A significant upward shift to the right of the relationship was observed during norepinephrine infusion. CONCLUSION: It was concluded that norepinephrine exerted a favourable effect on right ventricular function.     

Quantification of ischaemia induced vulnerability by precordial T wave alternans analysis in dog and human

OBJECTIVE: The aim was to examine the regional specificity of T wave alternans and the value of precordial ECG monitoring for non-invasive tracking of cardiac vulnerability during acute coronary artery occlusion and reperfusion in animals and humans. METHODS: The left ventricular ECG was monitored during two acute occlusions of the left anterior descending coronary artery and subsequent reperfusion in each of 61 chloralose anaesthetised dogs, and over 150,000 beats were analysed. In subgroups of these animals, lead II and precordial lead V5 were monitored or epicardial electrograms were recorded. In seven patients, lead II and precordial leads V1-6 were monitored during angioplasty. T wave alternans magnitude was quantified by complex demodulation. The same recording equipment and analytical methods were used in the clinical and experimental studies. RESULTS: A close temporal correspondence and linear correlation was found between T wave alternans magnitude--but not ST segment depression or ventricular premature beat incidence--and the incidence of spontaneous ventricular tachycardia and fibrillation during acute coronary artery occlusion and reperfusion. Epicardial electrograms showed alternans to be regionally specific, occurring in the ischaemic but not in the normal zones, and to predict spontaneous ventricular fibrillation and ventricular tachycardia (sensitivity = 79%, specificity = 86%). A significant linear relationship (r2 = 0.86, p < 0.01) between alternans magnitude detected in V5 and the left ventricular intracavitary lead indicates that the precordial leads could be used to assess cardiac vulnerability from the body surface. Lead V5 showed greater resolution than lead II. In humans, the precordial leads overlying the ischaemic zone were superior to lead II or Frank leads for alternans detection during both the occlusion and the reperfusion phases. In both animals and humans, alternation invariably occurred during the first half of the T wave, coinciding with the vulnerable period of the cardiac cycle and suggesting an important electrophysiological link to cardiac vulnerability. CONCLUSIONS: Alternans is regionally specific and is linearly projected to the precordium. Quantification of its magnitude in the precordial ECG may provide a non-invasive means for tracking cardiac vulnerability during acute myocardial ischaemia and reperfusion in both animals and humans.     

Right ventricular function after aorto-coronary bypass surgery: with relation to the site of right coronary artery occlusion

Postoperative right ventricular function was evaluated serially by thermodilution techniques (REF-1, Edwards Laboratories) in patients who underwent aorto-coronary bypass surgery with uneventful postoperative recovery. The patients were divided into three groups depending on the location of critical stenosis of the right coronary artery. The stenosis was proximal to the right ventricular branch in group I (n = 13), distal to the right ventricular branch but proximal to the acute marginal branch in group II (n = 13) and distal to the acute marginal branch in group III (n = 11). Control (n = 20) consisted of the patients with no significant stenosis of the right coronary artery. Cardiac index, intracardiac pressures and amount of cathecolamin used during postoperative course showed no significant differences among the groups including control. With the use of cathecolamine after surgery, right ventricular ejection fraction (RVEF) rose and right ventricular volumes (RVEDV and RVESV) decreased in all the groups except for group I. These values in group I were unchanged. Thus, there were significant differences in RVEF, RVEDV and RVESV between group I and control. These results mean that right ventricular dysfunction may remain even long after occlusion of the proximal right coronary artery.     

Diagnosis of right ventricular infarction by overlap images of simultaneous dual emission computed tomography using technetium-99m pyrophosphate and thallium-201

The validity of dual energy single-photon emission computed tomography (SPECT) with technetium-99m pyrophosphate (Tc-99m PPi) and thallium-201 for the diagnosis of right ventricular (RV) infarction, and the clinical features of RV infarction, were investigated in 190 patients with acute myocardial infarction. Diagnosis of RV infarction was performed by Tc-99m PPi accumulation in the RV myocardium on thallium-201 and Tc-99m PPi over-lay images at the dual SPECT with simultaneous imaging taken 2 to 9 days after the onset of myocardial infarction. Thirty RV infarctions were found among the 190 patients with left ventricular infarction (15.8%): 29 (97%) in association with the inferior and 1 (3%) with the lateral infarction. Tc-99m PPi accumulation was mostly observed in the posterior wall of the right ventricle. A total occlusion or a severe stenosis of the right coronary artery was demonstrated angiographically in 92% of the patients with RV infarction. The prevalence of RV infarctions was significantly lower in patients who achieved successful early reperfusion than in those who did not (26.7 vs 68.4%, respectively, p < 0.01). However, a successful early reperfusion therapy could not significantly decrease the rate of RV involvement in patients without significant collateral flow (p < 0.01). Thus, dual isotope SPECT with Tc-99m PPi and thallium-201 can be used as a reliable method for the diagnosis of RV infarction.     

ST elevation during ergometric test: correlation with coronary angiography

BACKGROUND: ST elevation during ergometric stress test (EST) is relatively rare. Its prevalence depends upon the tested population but occurs more frequently in patients who have had myocardial infarction or variant angina. This phenomenon is very rare in patients with typical exertional angina and its pathogenesis is still unclear. MATERIAL AND METHODS: We studied a group of 75 consecutive patients with exertional angina who underwent EST and coronary angiography. A symptom limited EST was performed in the upright position on a cycloergometer with load increases of 25 watts every 3 minutes and 12 leads were monitored during all test. Coronary angiography was performed according to Judkins technique. From these patients, according to Froelicher's criteria, a group of 49 patients (age 32-68, mean 51.6 years), without myocardial infarction and/or left ventricular asynergy, was selected. RESULTS: All patients had a coronary artery disease (16 patients with 3 vessels, 11 patients with 2 vessels and 22 patients with 1 vessel disease). The EST was positive for ST depression in 31 patients (63.3%) and for ST elevation in 5 patients (10.1%), while 13 patients (26.6%) had a non diagnostic EST. The ST elevation occurs in V1-V2 and it was associated in all cases with a stenosis in the left anterior descending (LAD) artery. Therefore we divided the 19 patients with LAD stenosis into two subgroups: subgroups A (9 patients, mean age 49.6 years) with LAD stenosis > or = 90% and subgroups B with LAD stenosis between 70% and 90%. ST elevation occurs in 5 patients (55.5%) of subgroup A and in no patient of the subgroup B. Moreover, in the subgroup A ST elevation seems to be related to the anatomic localization of the stenosis: in fact it appears in 83.3% of patients with LAD stenosis located before the onset of the first diagonal branch. CONCLUSIONS: From these data it can be desumed that ST elevation in V1-V2 that occurs in patients with exertional angina and without myocardial infarction or variant angina is strongly predictive of a very important LAD stenosis.     

Endothelin A receptor blockade causes adverse left ventricular remodeling but improves pulmonary artery pressure after infarction in the rat

BACKGROUND: Endothelin A (ETA) receptor antagonists have been shown to improve ventricular remodeling and survival in rats when started 10 days after infarction. Whether starting them earlier would have a more or less beneficial effect is uncertain. METHODS AND RESULTS: Rats surviving an acute myocardial infarction (MI) for 24 hours (n=403) were assigned to saline or the ETA receptor antagonist LU 127043 or its active enantiomer LU 135252 for 4 weeks. Chronic LU treatment had no effect on survival, with 46% of LU rats and 47% of saline-treated rats with large MI surviving to the end of the study. LU treatment led to scar thinning, further left ventricular (LV) dilatation, an increase in LV end-diastolic pressure, and an increase in wet lung weight (P<0.05). Despite this detrimental effect on LV function, LU led to a significant decrease in RV systolic (50+/-2 to 44+/-2 mm Hg, P<0.05 vs saline) and right atrial pressures. LU treatment also prevented the increase in pulmonary ET-1 found in saline-treated rats with large MI but did not modify the increase in cardiac ET-1 in hearts with large MI. CONCLUSIONS: The early use of the ETA receptor antagonists LU 127043 or its active enantiomer LU 135252 after infarction in the rat leads to impaired scar healing and LV dilatation and dysfunction. This is accompanied by a decrease in RV systolic and right atrial pressures and a decrease in pulmonary but not cardiac ET-1 levels. It would thus appear that the early use of ETA receptor antagonists after infarction may be detrimental.     

Effects of dichloroacetate in patients with congestive heart failure

BACKGROUND: Conventional approaches to management of congestive heart failure (CHF) rely on drugs that increase myocardial contractility or reduce ventricular afterload. These approaches often improve cardiac symptoms and survival, but may be associated with significant deleterious effects. An alternative approach is to enhance myocardial energy production. Dichloroacetate (DCA) stimulates pyruvate dehydrogenase activity and accelerates aerobic glucose, pyruvate, and lactate metabolism in myocardial cells. These alterations would be expected to improve myocardial function. HYPOTHESIS: The purpose of the investigation was to assess the efficacy of DCA in patients with left ventricular systolic dysfunction and to examine the mechanism by which improvement occurs. METHODS: A total of 25 patients (16 men, 9 women; age range 31-72 years, mean 59) with CHF and ejection fraction < or = 40% received an intravenous infusion of 50 mg/kg DCA over 15 min. Indices of systolic and diastolic function were obtained by two-dimensional and Doppler echocardiography performed at baseline, 30 min, and 60 min following completion of DCA infusion. RESULTS: Baseline ventricular ejection fraction was 27.3 +/- 9.1%; 17 patients (68%) had nonischemic cardiomyopathy. Heart rate increased after DCA infusion from 73.9 +/- 14.5 to 79.2 +/- 14.9 beats/min at 60 min; p = 0.02. Left ventricular diastolic and systolic volumes increased at 30 min compared with baseline (248.7 +/- 98.1 vs. 259.6 +/- 99.6; p = 0.04, and 180.1 +/- 80.4 vs. 192.2 +/- 84.9; p = 0.002, respectively), but stroke volume (49.2 +/- 19.1 vs. 48.9 +/- 18.1; p = 0.9) and ejection fraction (27.3 +/- 9.1 vs. 25.7 +/- 9.8; p = 0.2) were unchanged. Indices of diastolic function were also unchanged. CONCLUSION: Dichloroacetate infusion in patients with CHF is not associated with improvement in noninvasively assessed left ventricular function.     

Intravenous immunoglobulin inhibits IgE production in human B lymphocytes

This study sought to determine the prevalence of spontaneous reperfusion of an infarct-related artery (IRA) and associated myocardial salvage in the absence of thrombolysis or angioplasty. Twenty-one patients with acute myocardial infarction received only heparin and aspirin. At a median of 18 hours after presentation, 12 patients (57%) had angiographic patency of the IRA. Technetium-99m sestamibi was injected acutely on presentation and again at hospital discharge. Acute and final perfusion defect sizes were measured. Their difference, myocardial salvage, was calculated along with salvage index (myocardial salvage/acute defect). Comparing patients with a patent versus occluded IRA, myocardium at risk was similar (16% +/- 12% vs 12% +/- 9% left ventricle, p = NS); however, myocardial salvage (9% +/- 9% vs -2% +/- 7% left ventricle, p = 0.01), and salvage index (0.62 +/- 0.37 vs 0.19 +/- 0.33, p = 0.01) were greater in patients with spontaneous reperfusion. Resolution of chest pain was greater in patients with a patent IRA (100% vs 55%, p = 0.003). Spontaneous reperfusion of the IRA occurs frequently in patients with acute myocardial infarction and is associated with significant myocardial salvage.