Angioplasty induced myocardial ischaemia prolongs the signal-averaged P-wave duration in single vessel coronary artery disease.

Aims The P-wave duration (PWD) has been shown to prolong in conditions associated with elevated left ventricular end-diastolic and left atrial pressures, which also increase during transient coronary artery occlusions such as angioplasty. The aim of this study was to investigate the effects of angioplasty-induced myocardial ischaemia on signal averaged PWD in patients undergoing coronary angioplasty. Methods Eighty-four consecutive adult patients with single-vessel coronary artery disease undergoing elective coronary angioplasty were included. Duration of the P wave before and during coronary angioplasty were evaluated using signal averaged P-wave analysis. Patients were classified in groups according to the artery occluded, as left anterior descending (LAD) Group, right coronary artery (RCA) Group or Others Group (which included obtuse marginal, circumflex or diagonal). Results Patients included in the LAD, RCA and Others groups were similar with respect to clinical characteristics. The mean PWD at baseline was similar in all lesions (P>0.05), whereas mean PWD at inflation was significantly longer in LAD Group compared with RCA (126.1 +/- 9.5 ms vs 118.7 +/- 10.4 ms, P=0.007) and Others (126.1 +/- 9.5 ms vs 116.3 +/- 8.6 ms, P<0.001). The PWD during balloon inflation was significantly prolonged in all groups compared with baseline levels (LAD Group 126.1 +/- 9.6 ms vs 109.7 +/- 8.0 ms; RCA Group 118.7 +/- 10.4 ms vs 108.3 +/- 8.4 ms and Others Group 116.3 +/- 8.6 ms vs 109.7 +/- 6.0 ms, all P values <0.001). Conclusion Signal-averaged PWD significantly increases during single-vessel coronary angioplasty. This increase is more pronounced for LAD lesions. However, the clinical implications of P-wave prolongation during balloon angioplasty and the value of PWD as a measure of ischaemia remains to be clarified.     

Correlation of remote ST segment depression and coronary anatomy during acute coronary occlusion

BACKGROUND: The appearance of remote ST segment depression (RSTD) on an electrocardiogram (ECG) is associated with more extensive infarction and a worse clinical outcome than when RSTD is absent. OBJECTIVE: To determine whether RSTD predicts coronary anatomy during acute coronary occlusion. It was hypothesized that RSTD is associated with the occlusion of a proximal lesion, an extensive artery and an artery without distal collateralization. PATIENTS AND METHODS: In 113 consecutive patients with single vessel disease undergoing percutaneous transluminal coronary angioplasty (PTCA), 12-lead ECGs (recorded at baseline and during balloon inflation) and angiographical data were analyzed independently. Patients with ST segment elevation in the primary territory and RSTD (greater than 1 mm ST depression at 80 ms after the J point) (group A) were compared with patients without RSTD (group B). Proximal lesions were defined as lesions located in the segments proximal to the acute marginal branch, first diagonal artery or first obtuse marginal branch. An extensive right coronary artery (RCA) was one that supplied the posterolateral wall; an extensive left anterior descending (LAD) artery was one that supplied the inferoapical wall; and an extensive circumflex artery was one that supplied the posterior descending artery. RESULTS: Fifty-four patients (48%) had PTCA of the proximal vessels, 43 patients (38%) had extensive target vessels and 11 patients (9.7%) had collaterals. Target vessels included 33% in RCA, 44% in LAD artery and 23% in circumflex artery. Forty-five patients (40%) developed RSTD during balloon inflation (group A). Patients in group A were more likely to have extensive vessels on the angiogram than those in group B (group A 49%, group B 31%; P=0.05). None of the patients in group A had collaterals to the culprit artery, while 16% of patients in group B did (P=0.003). The two groups were not significantly different with respect to the number of proximal lesions (group A 58%, group B 42%; P=0.08). Analysis performed according to the target artery revealed that RSTD was associated with occlusion of an extensive RCA during RCA occlusion (extensive RCA in group A 100%, group B 57%; P=0.006). For the LAD artery, RSTD was associated with proximal lesions (group A 74%, group B 41%; P=0.02) and absence of collaterals (group A 100%, group B 74%; P=0.01). CONCLUSIONS: During acute coronary occlusion, the presence of RSTD on 12-lead ECG was specific for the absence of collaterals. The presence of RSTD during RCA occlusion was strongly associated with an extensive RCA, suggestive of posterolateral wall ischemia. During LAD artery occlusion, the presence of RSTD was associated with proximal occlusion, which resulted in ischemia of the LAD artery and the major diagonal artery territories.     

P波特征与冠状动脉旁路移植术后心房颤动关系的Meta分析

目的 通过Meta分析综合评价冠状动脉旁路移植术前12导联心电图P波时限、信号平均心电图P波时限及P波离散度与冠状动脉旁路移植术后心房颤动（房颤）的关系.方法 通过进行文献质量评价,应用RevMan 4.3软件进行敏感性和异质性分析后计算综合效应.结果 13篇文献符合纳入标准.Meta分析结果显示,冠状动脉旁路移植术后发生房颤患者的术前12导联心电图P波时限和信号平均心电图P波时限均比未发生房颤患者长.加权均数差（WMD）分别为3.69ms,95%CI 1.93～5.44 12.23ms,95%CI 4.82～19.63.术前P波离散度两组之间差异无统计学意义.术后P波离散度的增加是否是术后房颤的独立预测因子未获得综合效应.结论 术前12导联心电图P波时限和信号平均心电图P波时限延长与术后房颤高发有关,P波离散度的增加与术后房颤的关系有待进一步研究.     

Evaluation of very low amplitude intra-QRS potentials during the initial minutes of acute transmural myocardial ischemia

Introduction

Low-level electrocardiographic changes from depolarization wavefront may accompany acute myocardial ischemia. The purpose of this study was to assess the changes of microvolt amplitude intra-QRS potentials induced by elective percutaneous coronary interventions (PCI).

Methods

Fifty-seven patients with balloon inflation periods ranging from 3.1 to 7.3 minutes (4.9 ± 0.7 min) were studied. Nine leads continuous high-resolution ECG before and during PCI were recorded and signal-averaged. Abnormal intra-QRS at microvolt level (μAIQP) were obtained using a signal modeling approach. μAIQP, R-wave amplitude and QRS duration were measured in the processed ECG during baseline and PCI episodes.

Results

The mean μAIQP amplitude significantly decreased for each of the standard 12 leads at the PCI event respect to baseline. Left anterior descending artery (LAD) occlusion resulted in a decrease μAIQP in both the precordial leads and the limb leads, while right coronary (RCA) and left circumflex (LCx) arteries occlusions mainly affected limb leads. R-wave amplitude increased during PCI in RCA and LCx groups in lead III but decreased in the precordial leads, while the amplitude decreased in the LAD group in lead III. The average duration of the QRS augmented in groups RCA and LCx but not in the LAD group.

Conclusions

Abnormal intra-QRS potentials at the level of μV provide an excellent tool to characterize the very-low amplitude fragmentation of the QRS complex and its changes due to ischemic injuries. μAIQP shows promise as a new ECG index to measure electrophysiologic changes associated with acute myocardial ischemia.     

Body surface mapping during percutaneous transluminal coronary angioplasty. QRS changes indicating regional myocardial conduction delay

Using a radiotransparent electrode array, body surface maps (BSMs) were constructed based on simultaneous recordings from 62 leads on the entire thorax before, during, and after balloon inflation during percutaneous transluminal coronary angioplasty (PTCA). Twenty-five patients were studied, and 30 angioplasties were performed; 20 patients had one-vessel disease, and five patients had two-vessel disease. In total, 15 dilations in the left anterior descending artery (LAD), seven in the right coronary artery (RCA), and eight in the left circumflex artery (LCx) were studied. For each patient, the BSM and the QRS integral map before, during, and after the inflation was compared by subtraction of recordings "during-minus-before" inflation and "before-minus-after" inflation. The subtraction was performed on the results of the QRS integral maps. The conclusions derived from the inspection of the BSMs and the difference maps show specific changes in the QRS complex during ischemia related to the corresponding ischemic segment in 21 of 25 patients in the three groups. An area of positive potentials remained present on the BSM during dilation, indicating a depolarization wave front. For the LAD group, positive potentials were seen on the anterior thorax and, for the RCA group, on the lower part of the thorax. By subtraction analysis, these changes were extracted and presented as difference maps. For the LCx group, the BSM revealed no changes in pattern but the difference map showed a difference vector pointing in a anteroposterior direction. A regional myocardial conduction delay was hypothesized as the most likely cause for the results.     

Differentiation between left circumflex and right coronary artery occlusions: studies on ST-segment deviation during percutaneous transluminal coronary angioplasty

To distinguish between acute occlusion of the right coronary artery (RCA) and the left circumflex artery (LCx) by electrocardiography, we studied ST-segment deviation during balloon inflation in percutaneous transluminal angioplasty. The composite electrocardiographic criteria based on ST-segment deviations increased the diagnostic specificity: that is, the finding of inferior infarction (ST-segment elevation in leads II, III, aVF) without lateral infarction (ST-segment elevation in leads V5,6) was highly suggestive of RCA occlusion (sensitivity and specificity: 35 of 43 cases, 81.4%; and 33 of 36 cases, 91.7%), whereas ST-segment elevation in leads V5,6 (LCx: 23 of 36 cases; 63.9%, RCA: 5 of 43 cases; 11.6%) or isolated ST-segment depression in leads V2-4 (LCx: 9 of 36 cases; 25.0%, RCA: none of 43 cases) was highly suggestive of LCx occlusion. These results indicate that the composite electrocardiographic criteria were useful in predicting the artery involved in acute myocardial infarction, although any single criterion was not sensitive or specific enough to differentiate right from left circumflex coronary artery occlusion.     

Neurocardiac Responses to Acute Coronary Balloon Occlusion in Humans

Both cardioinhibitory and sympathoexcitutory responses to transient coronary artery occlusion have been ascribed to activation of cardiac sensory receptors. Using autoregressive modeling, the power spectrum of heart rate variability was determined from continuous ECG records before, during (120 sec) and following coronary balloon occlusion in 17 patients with isolated single vessel coronary artery stenosis; 11 with left anterior descending (LAD) stenoses and 6 with either right coronary artery (RCA; n = 3) or circumflex (Cfx; n = 3) stenoses. There were no significant changes in heart rate or its variance either during balloon occlusion or following releuse for both the LAD and RCA/Cfx groups. However, during LAD occlusion there was a significant 27% increase in the low frequency (LF) power (60.5 ± 15.1 to 82.3 ± 25.4 b/min²/Hz; P < 0.05) and a 37% decrease in the high frequency (HF) power (28.9 ± 13.2 to 18.3 ± 9.7 b/min²/Hz;P < 0.05). An insignificant, but directionally opposite, trend was seen for the LF power during RCA/Cfx occlusions. Neither the presence nor absence of intracoronary collaterds, beta blockade, inflation induced ischemia, or history of previous myocardial infarction appeared to influence the effect of balloon inflation on either LF or HF values. The autospectral changes seen during transient LAD occlusion had not returned to control values within 30 minutes of balloon release. Thus, transient occlusion of an LAD artery stenosis elicits a shift in cardio-sympathovagal balance towards heightened sympathetic modulation of sinus node activity.     

Continuous monitoring of coronary venous oxygen saturation during PTCA and its relation to electrocardiographic ST changes]

The purpose of this study was to investigate change in coronary venous oxygen saturation (CSO2-Sat) during percutaneous transluminal coronary angioplasty (PTCA) and to compare the results with those of standard 12-lead ECGs (s-ECG) and epicardial ECG induced using an intracoronary guidewire (ic-ECG). CSO2-Sat was measured continuously in 10 patients undergoing PTCA; 5 patients with lesions in the left anterior descending coronary artery (LAD), one with lesions in the left circumflex artery (LCX), and 4 with right coronary artery (RCA) lesions. The results were as follows: 1. In all 6 patients with stenotic lesions in the left coronary artery, CSO2-Sat decreased by 5 to 22% immediately after balloon inflation. Significant changes in ic-ECG (ST deviation > or = 0.1 mV) were observed in 5 of the 6 patients, while significant changes in s-ECG (ST deviation > or = 0.1 mV) were observed in only 3 of the 6 patients. The s-ECG did not seem to be sensitive enough to represent myocardial ischemia in the LCX. 2. The interval from the balloon inflation to the significant change was shorter for CSO2-Sat than for the ECGs in 4 of the 5 patients with LAD lesions, except Case 4. The recovery time of CSO2-Sat to the basal level on balloon deflation was longer than the recovery times of ic-ECG and s-ECG. 3. There was no significant change in the CSO2-Sat in 3 of the 4 patients undergoing PTCA for RCA lesions, while significant changes were observed in the ic-ECG and s-ECG in all 4 patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

93例急性心肌梗死患者的心电图及冠脉造影分析

目的探讨急性心肌梗死患者心电图sT改变的导联与冠状动脉罪犯血管的关系。方法对93例急性心肌梗死患者心电图ST段改变与选择性冠状动脉造影结果进行对比分析。结果心电图V1-V4sT抬高伴Ⅱ、Ⅲ、aVFST段下移的罪犯血管主要为左前降支（LAD）,少数前壁心肌梗死伴下壁sT段抬高;Ⅱ、Ⅲ、aVFST抬高伴V1-V4 ST段下移的主要罪犯血管为右冠状动脉（RCA）,少部分为左回旋支（LCX）,极少部分为LAD;胸前导联T高尖与ST抬高导联不一致可排除LAD;高侧壁Ⅰ、AVLST段抬高多数罪犯血管为LCX。结论心电图ST改变的导联对急性心肌梗死罪犯血管能进行初步预测。     

Comparison of epicardial potential maps derived from the 12-lead electrocardiograms with scintigraphic images during controlled myocardial ischemia

Our aim was to cross-validate electrocardiographic (ECG) and scintigraphic imaging of acute myocardial ischemia. The former method was based on inverse calculation of heart-surface potentials from the body-surface ECGs, and the latter, on a single photon emission computed tomography (SPECT). A boundary-element torso model with 352 body-surface and 202 heart-surface nodes was used to perform the ECG inverse solution. Potentials at 352 body-surface nodes were calculated from those acquired at 12-lead ECG measurement sites using regression coefficients developed from a design set (n = 892) of body-surface potential mapping (BSPM) data. The test set (n = 18) consisted of BSPM data from patients who underwent a balloon-inflation angioplasty of either the left anterior descending coronary artery (LAD) (n = 7), left circumflex coronary artery (LCx) (n = 2), or the right coronary artery (RCA) (n = 9). Body-surface potential mapping distributions at J point for 352 nodes were estimated from the 12-lead ECG, and an agreement with those estimated from 120 leads was assessed by a correlation coefficient (CC) (in percent). These estimates yielded very similar BSPM distributions, with a CC of 91.0% ± 8.1% (mean ± SD) for the entire test set and 94.1% ± 1.4%, 96.7% ± 0.8%, and 87.4% ± 10.3% for LAD, LCx, and RCA subgroups, respectively. Corresponding heart-surface potential distributions obtained by inverse solution correlated with a lower CC of 69.3% ± 18.0% overall and 73.7% ± 10.8%, 84.7% ± 1.1%, and 62.6% ± 21.8%, respectively, for subgroups. Bull's-eye displays of heart-surface potentials calculated from estimated BSPM distributions had an area of positive potentials that qualitatively corresponded, in general, with the underperfused territory suggested by SPECT images. For the LAD and LCx groups, all 9 ECG-derived bull's-eye images indicated the expected territory; for the RCA group, 6 of 9 ECG-derived images were as expected; 2 of 3 misclassified cases had very small ECG changes in response to coronary-artery occlusion, and their SPECT images showed indiscernible patterns. In conclusion, our findings demonstrate that noninvasive ECG imaging based on just the 12-lead ECG might provide useful estimates of the regions of myocardial ischemia that agree with those provided by scintigraphic techniques.     

P‐Wave Dispersion: A Novel Predictor of Paroxysmal Atrial Fibrillation

Background: The prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with paroxysmal atrial fibrillation (AF). Previous studies have demonstrated that individuals with a clinical history of paroxysmal AF show a significantly increased P‐wave duration in 12‐lead surface electrocardiograms (ECG) and signal‐averaged ECG recordings. Methods: The inhomogeneous and discontinuous atrial conduction in patients with paroxysmal AF has recently been studied with a new ECG index, P‐wave dispersion. P‐wave dispersion is defined as the difference between the longest and the shortest P‐wave duration recorded from multiple different surface ECG leads. Up to now the most extensive clinical evaluation of P‐wave dispersion has been performed in the assessment of the risk for AF in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease and in patients undergoing coronary artery bypass surgery. P‐wave dispersion has proven to be a sensitive and specific ECG predictor of AF in the various clinical settings. However, no electrophysiologic study has proven up to now the suspected relationship between the dispersion in the atrial conduction times and P‐wave dispersion. The methodology used for the calculation of P‐wave dispersion is not standardized and more efforts to improve the reliability and reproducibility of P‐wave dispersion measurements are needed. Conclusions: P‐wave dispersion constitutes a recent contribution to the field of noninvasive electrocardiology and seems to be quite promising in the field of AF prediction. A.N.E. 2001;6(2):159–165     

Two-dimensional echocardiography during percutaneous transluminal coronary angioplasty

In order to study myocardial and clinical events during transient coronary occlusion in humans, two-dimensional echocardiography was continuously performed in 15 patients undergoing 49 balloon inflations during percutaneous transluminal coronary angioplasty (PTCA). Transient segmental asynergy developed in all patients 8 +/- 3 seconds after balloon inflation and returned to baseline 19 +/- 8 seconds after balloon deflation. Segmental dyskinesis was seen in only 8 of 11 patients undergoing PTCA of the left anterior descending artery (LAD). A wall motion score, based on degree of asynergy of 13 segments of the left ventricle, was significantly higher during LAD than during right coronary artery inflation (7.9 +/- 1.3 vs 4.0 +/- 1.4, p less than 0.01). Left ventricular size index increased significantly during balloon inflation, from 179 +/- 9 to 196 +/- 10 mm (p less than 0.01). Four patients developed transient ST segment changes in the extremity leads of the ECG and five patients had angina pectoris. The very first sign of ischemia in three patients, who developed all of these symptoms together, was consistently asynergy, followed by ECG changes, and last, angina pectoris. Thus during PTCA, transient asynergy and left ventricular dilatation develop, which are often clinically silent.     

Inverted U wave in ergonovine-induced vasospastic angina

The relationship between inverted U wave in leads V5 and II and the location of myocardial ischemia was studied in 52 positive patients and in 50 negative patients with ergonovine provocation test. Development of a biphasic or negative U wave, or increased negativity of U wave (inverted U wave) was observed in 15 of 17 patients with spasm in only the right coronary artery (RCA), in 6 of 8 with spasm in only the left anterior descending artery (LAD), in 2 of 8 with spasm in only the left circumflex artery (LCx), and in 23 of 24 with spasm in two or more vessels. Of 52 positive patients in the ergonovine provocation test, 46 (88.5%) had inverted U wave. Of these, 17 (32.7%) had inverted U wave without discernible ST deviation. Of 50 negative patients, 2 had inverted U wave. Inverted U wave in lead V5 was frequently seen in patients with spasm of LAD, but this finding was not uncommon in spasm of RCA or LCx. On the other hand, inverted U wave in lead II was frequently seen in spasm of RCA and LCx, but not in spasm of LAD. These findings suggest that inverted U wave in lead V5 is not specific for myocardial ischemia due to spasm of LAD and that inverted U wave in lead II is specific for spasm of RCA and LCx.     

Acute myocardial infarction with simultaneous occlusions of two major coronary arteries in a young man

Simultaneous formation of the thrombi in two different coronary arteries is a very rare event. We present a 34-year-old man with acute myocardial infarction due to simultaneous occlusion of the two major coronary arteries. His only risk factor was smoking 40 cigarettes daily. Emergency arteriography revealed a total occlusion of the proximal left anterior descending artery (LAD) and the left circumflex coronary artery (LCx). We performed primary angioplasty to the LAD and instituted thrombolytic therapy to the LCx. During intra-aortic balloon pumping and medical treatment, the patient had no symptoms of angina. He underwent a second catheterization 4 weeks after primary angioplasty. After intravenous ergonovine provocation, coronary arteriography revealed diffuse vasospasm of the LAD and the LCx. These data suggest that habitual heavy smoking and coronary spasm may have been causatory factors for myocardial infarction in this case.     

Left ventricular function during transient coronary occlusion: digital subtraction left ventriculograms during coronary angioplasty

The impact of transient myocardial ischemia on left ventricular function was examined by digital subtraction left ventricular angiography. Contrast medium was injected into the right pulmonary artery before, at 60 seconds of balloon inflation, and 10 minutes after balloon deflation. A total of 69 patients completed the study. In 52 patients, the left anterior descending artery (LAD) was involved, and in 17, the right coronary artery (RCA) was the focus. Ejection fraction (EF) declined by balloon inflation and returned to baseline value after deflation of the balloon. There was tendency toward a lower EF and wider akinetic area for LAD dilatation. The linear correlation between resting EF and EF during balloon inflation suggested that the effect of momentary coronary occlusion on left ventricular function appears to be additive to pre-existing left ventricular dysfunction, and resting ejection fraction is an important parameter for estimating the degree of diminished left ventricular function during myocardial ischemia.     

Detection of culprit coronary lesion location in pre-hospital 12-lead ECG

BackgroundPre-hospital 12-lead ECG interpretation is important because pre-hospital activation of the coronary catheterization laboratory reduces ST-segment elevation myocardial infarction (STEMI) discovery-to-treatment time. In addition, some ECG features indicate higher risk in STEMI such as proximal left anterior descending (LAD) culprit lesion location. The challenging nature of the pre-hospital environment can lead to noisier ECGs which make automated STEMI detection difficult. We describe an automated system to classify lesion location as proximal LAD, LAD, right coronary artery (RCA) and left circumflex (LCx) and test the performance on pre-hospital 12-lead ECG.MethodsThe overall classifier was designed from three linked classifiers to separate LAD from non-LAD (RCA or LCx) in the first step, RCA from LCx in a second classifier and proximal from non-proximal LAD in the third classifier. The proximal LAD classifier was designed for high specificity because the output may be used in the decision to modify treatment. The LCx classifier was designed for high specificity because RCA is dominant in most people. The system was trained on a set of emergency department ECGs (n = 181) and tested on a set of pre-hospital ECGs (n = 80). Both sets were based on a sequential sample starting with symptoms suggesting acute coronary syndromes. Culprit lesion location was determined from coronary catheterization laboratory reports. Inclusion criteria included STEMI interpretation by computer and culprit lesion with 70% or more narrowing. Algorithm accuracy was measured on the test set by sensitivity (SE), specificity (SP), and positive predictive value (PPV).ResultsSE, SP and PPV were 50, 100 and 100% respectively for proximal LAD lesion location; 90, 100 and 100% for all LAD; 98, 72 and 78% for RCA; and 50, 98 and 90% for LCx. Specificity and PPV were high for proximal LAD, LAD and LCx. Specificity and PPV are not as high for RCA by design since the RCA-LCx tradeoff favors high specificity in LCx.ConclusionAlthough our test database is not large, algorithm performance suggests culprit lesion location can be reliably determined from pre-hospital ECG. Further research is needed however to evaluate the impact of automated culprit lesion location on patient treatment and outcomes.     

Correspondence between left ventricular 17 myocardial segments and coronary arteries.

AIMS: The last guidelines recommend a standardized 17-segment model for tomographic imaging of the left ventricle. The aim of this study is to analyse the correspondence of the 17 left ventricular segments with each coronary artery by myocardial perfusion SPECT studies. METHODS AND RESULTS: Fifty patients selected for percutaneous revascularization of one coronary artery [24 left anterior descending (LAD), 15 right coronary artery (RCA), and 11 left circumflex (LCX)] were included. The (99m)Tc-labelled compound was injected immediately after the inflation of the balloon during percutaneous coronary angioplasty. At least 90 s of complete occlusion time was required. Maximal contour of regions of hypoperfusion corresponding to each coronary artery occlusion were delineated over the polar map of 17 segments. Nine segments corresponded to only one coronary artery: eight to LAD (basal anterior, basal anteroseptal, mid-anterior, mid-anteroseptal, apical anterior, apical septal, apical lateral, and apex) and one to LCX (basal anterolateral). Basal inferoseptal, mid-inferoseptal, and apical inferior segments could correspond to LAD or RCA. Basal inferior, basal inferolateral, mid-inferior, and mid-inferolateral segments could correspond to RCA or LCX, whereas the mid-anterolateral segment could correspond to LAD or LCX. CONCLUSION: The most specific segments (anterior, anteroseptal, and all apical segments except the infero-apical) correspond to LAD but no segment can be exclusively attributed to the RCA. Inferoseptal segments can be attributed to LAD or RCA, inferior and inferolateral segments to RCA or LCX, and mid-anterolateral segment to LAD or LCX.     

Transient alterations of the QRS complex and ST segment during percutaneous transluminal balloon angioplasty of the left anterior descending coronary artery

Using continuous 3-lead electrocardiographic (ECG) recordings in 19 patients undergoing elective percutaneous transluminal coronary artery angioplasty (PTCA) of the left anterior descending (LAD) artery, this study described the dynamic changes of the ST segment and the R- and S-wave amplitudes that occur during transient myocardial ischemia. The waveforms from lead V2 were quantified at 10-second intervals during the length of the balloon inflation that produced the greatest extent of ST-segment deviation. The simultaneous changes that occurred in leads aVF and V5 were also observed, but not quantified. Measurements of R- and S-wave amplitudes were performed during maximal ischemia from both the PR- and the J-ST-segment baselines to determine which of these most nearly maintained its control position during ischemia. The results indicate that the R-wave amplitude is best determined from the PR-segment baseline (p = 0.0007), while the S wave is best determined from the J-ST-segment baseline (p = 0.03). However, only a portion of the QRS changes observed during PTCA could be accounted for by the baseline shift. There were additional QRS changes during ischemia in 11 of the patients (58%) suggestive of conduction disturbances in 3 endocardial sites: left septal, right septal and left anterosuperior. It is hypothesized that these changes may represent ischemia-induced delay in conduction ("periischemic block") previously thought to occur only with myocardial infarction.     

快速心房刺激对P波时限及离散度的影响

目的分析快速心房刺激对P波时限及离散度的影响.方法在74例射频消融术及82例经食管心房调搏检查中,用180ppm的S1S1刺激心房3min,在刺激前后立刻记录12导联同步心电图,通过心电图测出刺激前后的最大P波时限、最小P波时限及P波离散度,然后进行比较.结果射频消融组最大P波时限在心房刺激后比刺激前有显著性延长（p=0.002）,最小P波时限及P波离散度无显著性差异,食管心房调搏组最大P波时限及P波离散度在心房刺激后比刺激前有显著性增加（p=0.001）,最小P波时限无显著性差异.结论快速心房刺激能引起心房传导时间延长,非均质电活动的离散程度增加.最大P波时限及P波离散度是可以用来评价心房电重构的简便而无创的指标.     

Localization and quantification of myocardium at risk by myocardial perfusion SPECT during coronary artery occlusion

INTRODUCTION AND OBJECTIVES: The aim of this study was to analyze the distribution and extent of the myocardium at risk using polar maps obtained with myocardial perfusion SPECT. Myocardial perfusion of territories irrigated by the left anterior descending (LAD), right coronary (RCA) and left circumflex artery (CX) was studied with the help of a technetium-radiolabeled tracer during occlusion of the vessels in the course of percutaneous coronary angioplasty. PATIENTS AND METHOD: We studied 50 patients (24 LAD, 15 RCA and 11 CX). The 99mTc compound was injected immediately after inflation of the balloon, and the artery was occluded for approximately 90 seconds. Tomographic images were acquired, and polar maps showing the extent of the ischemic region (uptake < 50% of maximum) were generated. RESULTS: Mean percentage extent of the ischemic territory was 49.8 +/- 10.3% (minimum 35%, maximum 67%), for the proximal LAD, 39.8 (8.3%) (minimum 20%, maximum 51%) for the mid LAD, 20.3 (7.6%) (minimum 8.3%, maximum 35%) for the RCA, and 21.3 (10.8%) (minimum 10.2%, maximum 30%) for the CX. CONCLUSIONS: The contours and extent of the jeopardized myocardial territory found during coronary occlusion allowed us to generate polar maps that illustrated actual coronary risk. The distribution and extent of the areas at risk differed from those in polar maps generated by most current applications used with myocardial perfusion SPECT.