Vectorelectrocardiography in coronary artery disease

Continuous ST-segment monitoring by either continuous 12-lead ECG or continuous vectorcardiography provides reliable information regarding ST changes in patients with ongoing myocardial ischemia with or without concurrent chest pain. ST-segment monitoring enables the clinician to continuously follow the dynamic changes that characterize unstable angina and acute myocardial infarction syndromes. It provides important information for risk stratification in unstable coronary syndromes and helps in differentiating between extra-cardiac chest pain and acute coronary disease. The use of VECG for detection of perioperative myocardial damage is promising but much work still needs to be done to clarify the prognostic and clinical value of VECG in this setting.     

Early diagnosis and exclusion of acute myocardial infarction by two hours' vector-ECG and determination of either myoglobin or CK-mb. BIOMACS-study. BIOchemical Markers in Acute Coronary Syndromes

This retrospective study assesses the early diagnostic potential of a combination of multilead continuous vectorcardiography (VCG) and biochemical markers (myoglobin, troponin-t and CK-mb mass) in patients with chest pain who present with suspected acute myocardial infarction (AMI), but without ST-elevation on resting 12-lead ECG on admission. Within a multicenter study 56 patients admitted for chest pain (< 12 h) and with a non-diagnostic 12-lead ECG on admission and a VCG recording were included. Venous blood samples were drawn on admission and the continuous VCG was monitored for 2 h. The results were related to the clinical diagnosis of AMI. Neither the biochemical markers nor VCG alone permitted the diagnosis or exclusion of AMI at admission. However, if either analysis of myoglobin on admission or 2 h of VCG recording were positive, they would have a sensitivity for detection of AMI of 100% and specificity of 69%. In a subset of patients with more than 4 h delay since start of chest pain, CK-mb could replace myoglobin and give a sensitivity of 100% and a specificity of 81%. Determination of myoglobin or CK-mb at admission and VCG monitoring for 2 h can reliably confirm or exclude AMI within 2 h. This combination seems useful for early stratifications of patients in chest pain or coronary care units.     

Computer-assisted electrocardiography in structured diagnosis of acute myocardial infarction

The purpose of this study was to investigate the applicability of computerized electrocardiogram interpretation in classifying patients with suspected acute myocardial infarction. Computerized acquisition and analysis of the 12-lead electrocardiogram can increase the consistency and reduce the workload of patient classification. The serial electrocardiograms of 311 consecutive patients with suspected myocardial infarction were studied and a new computerized myocardial infarction (CMI) electrocardiographic classification was developed and compared with one commercially available and two manual codes. Statistically, there was almost no correlation between the four ECG codes. Compared with the WHO enzymatic criteria, the sensitivity of the CMI code toward detecting definite and possible infarction was 69.2% and 29.8% with a specificity of 62.1% and 79.7%, respectively. In subjects without previous infarction (n = 214) the sensitivity of the CMI code for definite enzymatic infarction was 71.9% and specificity 77.6%. Substituting the CMI for the Minnesota code had no effect on patient classification by the WHO MONICA criteria in 78% of patients with first infarction. Judged by cardiac macromolecular leakage, all electrocardiographic classifications of possible infarction were poorly correlated with myocardial tissue injury. We have developed a new computerized coding system to detect electrocardiographic myocardial infarction. The structure of the code allows interactive redefinition of criteria to meet user-defined needs. However, because of the weak relationship between electrocardiographic and biochemical criteria of myocardial injury, the role of ECG in the diagnostic classification of acute ischemic syndromes should be re-evaluated.     

Early Diagnosis and Exclusion of Acute Myocardial Infarction by Two Hours' Vector-ECG and Determination of Either Myoglobin or CK-mb

This retrospective study assesses the early diagnostic potential of a combination of multilead continuous vectorcardiography (VCG) and biochemical markers (myoglobin, troponin-t and CK-mb mass) in patients with chest pain who present with suspected acute myocardial infarction (AMI), but without ST-elevation on resting 12-lead ECG on admission. Within a multicenter study 56 patients admitted for chest pain (&lt;12 h) and with a non-diagnostic 12-lead ECG on admission and a VCG recording were included. Venous blood samples were drawn on admission and the continuous VCG was monitored for 2 h. The results were related to the clinical diagnosis of AMI. Neither the biochemical markers nor VCG alone permitted the diagnosis or exclusion of AMI at admission. However, if either analysis of myoglobin on admission or 2 h of VCG recording were positive, they would have a sensitivity for detection of AMI of 100% and specificity of 69%. In a subset of patients with more than 4 h delay since start of chest pain, CK-mb could replace myoglobin and give a sensitivity of 100% and a specificity of 81%. Determination of myoglobin or CK-mb at admission and VCG monitoring for 2 h can reliably confirm or exclude AMI within 2 h. This combination seems useful for early stratifications of patients in chest pain or coronary care units.     

Left bundle-branch block associated with acute inferior wall myocardial infarction.

The electrocardiographic manifestations of left bundle-branch block associated with acute inferior wall myocardial infarction are presented. The classic features of uncomplicated left bundle-branch block are modified in the following manner. The QRS complex is diminished in amplitude, and the S-T segment and T wave reflect primary changes: a coved, elevated S-T segment and an inverted, symmetrical T wave. These changes occur in leads orientated to the infarcted surface.     

Evaluation erweiterter Diagnostikverfahren bei der präklinischen Versorgung kardialer Notfälle

In our study we tested 2 different rapid assays for cardiac troponin t (TropT^®-rapid assay, diagnostic cut-off 0,2 ng/ml and TropTsensitive^®-rapid assay, diagnostic cut-off 0,1 ng/ml) in 75 chest pain patients. Additional to the emergency ECG (3-lead) we acquired a 12-lead ECG. The TropT^®-rapid assay showed a sensitivity of 11% (specifity 94,3%). The TropT sensitive^®-rapid assay showed a sensitivity of 62% (specifity 100%). In patients with acute myocardial infarction 12-lead ECG showed a sensitivity of 82% (3-lead ECG 24%). An risk-orientated check-up for thrombolysis contraindications should be done to identify risk-patients. Further education of emergency physicians in 12-lead ECG should be done.     

Minimal influence of anaesthesia and abdominal surgery on computerized vectorcardiography recordings

Myocardial infarction still represents a major cause of morbidity and mortality following surgical procedures. Continuous computerized on-line vector-ECG has previously been shown to be useful in the detection of myocardial ischaemia, in acute myocardial infarction and unstable angina pectoris and for ischaemia monitoring after PTCA procedures. This method was presently tested for the possible influence of anaesthesia and surgery during cholecystectomy under general anaesthesia (n = 9), and during inguinal hernia repairs using a spinal block (n = 5). The patients had no history, symptoms or signs of ischaemic heart disease. Analyses of vectorcardiographic changes were made in relation to predefined standardized anaesthetic and surgical procedures, all of which potentially could influence the vector-ECG. Three vectorcardiographic trend parameters were studied: QRS-vector difference, ST-vector magnitude and ST-change vector magnitude. The overall vectorcardiographic changes were minimal and smaller than vectorcardiographic changes previously reported during myocardial ischaemia and infarction. Since anaesthetic and surgical procedures per se had only minor effects on the vector ECG recordings, it is concluded that continuous computerized on-line vectorcardiography will not be skewed by these procedures. Hence, vectorcardiography has the potential of becoming a new monitor for the detection of perioperative myocardial ischaemia.     

Reversible electrocardiographic changes in severe acute asthma.

Previous reports have documented the occurrence of reversible electrocardiographic changes including right axis deviation, P pulmonale, right bundle-branch block, and ST-segment and T-wave abnormalities in patients with acute attacks of asthma. In a further systematic study, the electrocardiographs of 63 patients admitted with severe acute asthma have been evaluated. The most consistent change was an abnormally vertical P-wave axis in 78% of the patients. P pulmonale was present in 22% and right ventricular enlargement in only one patient. Right axis deviation, right bundle-branch block, and rhythm abnormality were not present in any patient. In 11%, ST-segment or T-wave abnormalities suggesting myocardial ischaemia were noted. These abnormalities persisted for up to nine days and were unexplained. Other ECG abnormalities in acute asthma may reflec positional changes of the heart due to overdistension of the lungs. All ECG changes resolved after clinical improvement.     

Vectorcardiography is superior to conventional ECG for detection of myocardial injury after coronary surgery

OBJECTIVE: The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. DESIGN: VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. RESULTS: Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. CONCLUSION: VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.     

Acute myocardial infarction with a non-diagnostic electrocardiogram. Case presentation and overview

The clinical presentation of a young hypertensive White man with acute high lateral non-transmural myocardial infarction (MI) is documented. This diagnosis was established on the grounds of a history of chest pain, elevated serial serum enzyme levels, technetium-99m pyrophosphate ('hot-spot') scintigraphy, exercise thallium-201 ('cold-spot') scanning, left ventricular cine angiography and selective coronary arteriography. Daily resting 12-lead ECGs failed to demonstrate unequivocal features of acute non-transmural subendocardial MI. The diagnostic difficulties facing the clinician in a case of acute MI associated with a non-diagnostic ECG are stressed, and the ECG features of acute subendocardial MI are reviewed.     

Intermittent complete left bundle branch block during general anesthesia

We report a case of intermittent complete left bundle branch block (CLBBB) which occurred during general anesthesia. An 83-year-old female was scheduled for upper lobectomy of the right lung under general anesthesia. Her preoperative 12-lead ECG showed atrial fibrillation and ST-depression in V4-6. Anesthesia was induced with propofol and pentazocine, and maintained with 0.5-1.5% isoflurane, 0-50% nitrous oxide in oxygen under close monitoring and appropriate respiratory management. The operation was performed uneventfully. Several minutes after the end of surgery, on converting her into the supine position from the left lateral decubitus position, widened QRS complexes, later diagnosed as CLBBB, appeared on ECG. At that time, heart rate was 92 beats x min(-1). After the administration of esmolol hydrochloride, heart rate decreased rapidly in a few minutes and ECG returned to normal conduction from CLBBB. We diagnosed this as rate-dependent intermittent CLBBB. Although intermittent CLBBB continued until the next day, the patient was asymptomatic and cardiac enzymes were within normal ranges. The intermittent CLBBB, which occasionally occurs during anesthesia, makes the diagnosis of myocardial ischemia and acute myocardial infarction difficult. The present case suggests that esmolol can be used effectively and safely to distinguish CLBBB as a benign disorder from myocardial ischemia in a patient with CLBBB.     

Acute myocardial infarction complicated by shock: outcome analysis based on initial electrocardiogram

Objectives. To assess the relation between initial ECG findings, presence of risk factors, coronary angiography findings, and clinical outcomes in patients with acute myocardial infarction complicated by cardiogenic shock (CS). Design. Data from a total of 5572 acute myocardial infarction patients admitted to the four tertiary hospitals during a period of 3 years were analyzed. CS on admission was present in 358 patients (6.4%). They were divided into four groups based on the admission ECG: ST-segment elevation (STEMI), ST-segment depression (STDMI), bundle branch block (BBBMI), and other ECG acute myocardial infarction. Results. CS developed most frequently among BBBMI patients (in 12.1% of all BBBMIs, p < 0.001 vs. STEMI), followed by STEMI (6.7%), STDMI (4.4%), and other ECG acute myocardial infarction (2.3%). The risk of CS development was similar in patients with left bundle branch block (LBBB) (13.3%) and right bundle branch block (RBBB) (11.2%). The one-year mortality was highest among RBBBMI patients (66.7%, p < 0.001), followed by LBBBMI (48.6%), other ECG (47.1%), STEMI (41.7%), and STDMI patients (38.1%). Conclusions. RBBB on admission ECG is associated with the highest risk of CS development, frequent left main coronary artery affection, and unsuccessful revascularization. It is also an independent predictor of one-year mortality.     

Postoperative 12-lead ECG predicts peri-operative myocardial ischaemia associated with myocardial cell damage

Peri-operative myocardial ischaemia is the single most important risk factor for an adverse cardiac outcome after non-cardiac surgery. The present study examines whether intermittent 12-lead ECG recordings can be used as an early warning tool to identify patients suffering from peri-operative myocardial ischaemia and subsequent myocardial cell damage. Fifty-five vascular surgery patients at risk for or with a history of coronary artery disease were monitored for peri-operative myocardial ischaemia using intermittent 12-lead ECG recordings taken pre-operatively and at 15 min, 20 h, 48 h, 72 h and 84 h postoperatively. The effectiveness of the 12-lead ECG was gauged by examining concordance with continuous 3-channel Holter monitoring and capturing peri-operative myocardial ischaemia by serial analyses of creatine kinase myocardial band isoenzyme and cardiac troponin T and I. The incidence of peri-operative myocardial ischaemia detected by 12-lead ECG was 44% and was identifiable in most patients (88%) 15 min after surgery. The incidence of peri-operative myocardial ischaemia detected by continuous monitoring was 53%, with the most severe episodes occurring intra-operatively and during emergence from anaesthesia. The concordance of the 12-lead method with continuous monitoring was 72%. The concordance of creatine kinase myocardial band isoenzyme activity with the 12-lead method was 71% and with Holter monitoring 57%. The concordance of mass concentration of creatine kinase myocardial band with 12-lead ECG recordings was 75%, and the corresponding value for Holter monitoring was 68%. The concordance of cardiac troponin T and I levels with the 12-lead method was 85% and 87%, respectively, and concordance with Holter monitoring was 72% and 66%, respectively. The postoperative 12-lead ECG identified peri-operative myocardial ischaemia associated with subsequent myocardial cell damage in most patients undergoing vascular surgery.     

Bundle branch block and acute myocardial infarction. Treatment and outcome

OBJECTIVE: To study early diagnosis, treatment and outcome in patients with bundle branch block and clinically suspected acute myocardial infarction. DESIGN: A prospective multicenter study including 14 Swedish coronary care units. The study included 257 consecutive patients with bundle branch block and clinical suspicion of acute myocardial infarction. RESULTS: Left bundle branch block was present in 62% of patients and right bundle branch block in 38%. Thrombolytic treatment of acute myocardial infarction in the left and right bundle branch block was 16% and 36%, respectively. Of those undergoing thrombolytic therapy, 20% of patients with left and 13% with right bundle branch block did not develop an acute myocardial infarction. Patients with left bundle branch block had higher mortality rates than those with right bundle branch block. After one year there was no difference in mortality rates between patients with and those without acute myocardial infarction on admission. CONCLUSION: Patients with bundle branch block and suspected acute myocardial infarction receive suboptimal treatment. Thus better diagnostic regimes are needed to identify those patients with bundle branch block and acute myocardial infarction who are suitable for thrombolytic treatment.     

Bundle Branch Block and Acute Myocardial Infarction: Treatment and Outcome

Objective - To study early diagnosis, treatment and outcome in patients with bundle branch block and clinically suspected acute myocardial infarction. Design - A prospective multicenter study including 14 Swedish coronary care units. The study included 257 consecutive patients with bundle branch block and clinical suspicion of acute myocardial infarction. Results - Left bundle branch block was present in 62% of patients and right bundle branch block in 38%. Thrombolytic treatment of acute myocardial infarction in the left and right bundle branch block was 16% and 36%, respectively. Of those undergoing thrombolytic therapy, 20% of patients with left and 13% with right bundle branch block did not develop an acute myocardial infarction. Patients with left bundle branch block had higher mortality rates than those with right bundle branch block. After one year there was no difference in mortality rates between patients with and those without acute myocardial infarction on admission. Conclusion - Patients with bundle branch block and suspected acute myocardial infarction receive suboptimal treatment. Thus better diagnostic regimes are needed to identify those patients with bundle branch block and acute myocardial infarction who are suitable for thrombolytic treatment.     

Vectorcardiography is Superior to Conventional ECG for Detection of Myocardial Injury after Coronary Surgery

Objective - The reliability of conventional scalar ECG for diagnosis of perioperative myocardial infarction (PMI) in cardiac surgery has been questioned. For the diagnosis of myocardial infarction in general vectorcardiography (VCG) is superior to ECG. Therefore, the usefulness of conventional VCG and computerized analysis of spatial VCG changes for diagnosis of PMI were studied. Design - VCG registrations were obtained from 218 patients undergoing coronary surgery. The spatial QRS vector loop area of each VCG registration was calculated and the loop area before surgery compared with the loop area after surgery. Conventional VCG criteria for myocardial infarction and set values for loop area reduction were related to sustained elevation of plasma troponin-T and clinical course. Results - Both conventional VCG criteria and spatial changes translated better than Q-waves on scalar ECG into elevation of biochemical markers of myocardial injury and impaired clinical course. Conclusion - VCG appears superior to conventional ECG as regards detection of myocardial injury in coronary surgery. Computerized programs have facilitated the registration and the interpretation of VCG and this methodology deserves further evaluation in cardiac surgery.     

Diagnosis of perioperative myocardial infarction after coronary artery bypass.

The diagnosis of perioperative myocardial infarction (POMI) in patients undergoing coronary artery bypass is uncertain because the criteria of infarction are unclear. Fifty patients who underwent coronary artery bypass were evaluated preoperatively and postoperatively with serial ECGs, creatine phosphokinase (CPK), isoenzyme determinations, and technetium pyrophosphate myocardial scans. Clinical evaluation correlated with exercise testing and postoperative angiography supported the diagnosis in questionable cases. Thirty-five patients (70%) had no evidence of POMI by any criteria, and 2 patients (4%) had unequivocal evidence of infarction by all criteria. Our studies indicate the complexities of diagnosing POMI. We believe that the serially recorded ECG is the most useful diagnostic technique. CPK isoenzyme determinations may be useful but are difficult to interpret in the operative setting. Preoperative cardiac scans are necessary so as to avoid a high incidence of false-positive scans postoperatively. In doubtful cases, postoperative coronary arteriography and left ventricular angiography may provide the most definitive information.     

Akuter Hinterwandinfarkt bei einem Patienten mit Dextrokardie und zuvor unbekanntem Situs inversus

A 60-year-old male patient was admitted for suspected myocardial infarction. The standard ECG recording showed an atypical axis (-140°) and non-specific ST-segment elevation in the inferior leads. As the clinical presentation was highly suspicious for myocardial infarction, the ECG was recorded again in a mirror-image position. With this recording, inferior myocardial infarction was diagnosed in this patient who was subsequently found to have a complete situs inversus. Mirror-image inversion of the ECG can be a rapid and easy tool for diagnosing myocardial infarction in patients with atypical standard ECG.     

Significance of right bundle branch block in the diagnosis of myocardial ischemia in patients undergoing coronary artery bypass grafting.

BACKGROUND: Perioperative diagnosis of myocardial ischemia following cardiac surgical procedures remains a challenging problem. Particularly, the role of new conduction disturbances as markers of postoperative ischemia is still questionable. The goal of this study was to elucidate the diagnostic significance of new postoperative right bundle branch block (RBBB) for the detection of perioperative myocardial ischemia in patients undergoing elective coronary artery bypass grafting (CABG). METHODS: In 169 consecutive patients, three-channel Holter monitoring and serial assessment of serum enzymes were performed for 48 h, and 12-lead ECG repeated for up to 5 days postoperatively. Postoperative events were classified as either myocardial infarction (MI), transient ischemic events (TIE) or various conduction disturbances. RESULTS: Transient (n=9) or permanent (n=4) RBBB occurred in 13 patients (8%); 14 patients (8%) showed signs of perioperative MI and 18 patients (11%) evidence of TIE. Peak activity of creatine-kinase (CK, 561+/-135 vs. 316+/-19, P<0.05) and CK-MB (22.7+/-3.2 vs. 13.4+/-0.8, P<0.01) were higher in patients with RBBB than in patients without perioperative ischemic events. Peak CK-MB levels were significantly higher in patients with MI as compared to those with RBBB (33.4+/-7.6 vs. 22.7+/-3.2, P<0. 05). Patients with TIE had similar perioperative enzyme levels as patients with no events. CONCLUSION: It is concluded that the combined assessment of repeated 12-lead ECG, continuous Holter monitoring and enzyme analysis allows a reliable diagnosis of perioperative myocardial ischemia and conduction disturbances. The occurrence of new RBBB following elective CABG is indicative of perioperative myocardial necrosis and thus serves as a valuable tool for the diagnosis of new, perioperative ischemic events.     

Traumatic coronary artery dissection after blunt thoracic trauma--a case report

We present a case of cardiac infarction after blunt chest trauma. The 49-year-old patient suffered from severe angina and the ECG demonstrated a pattern of acute anterior wall myocardial infarction. Acute coronary angiography was performed showing complete occlusion of the left interventricular coronary artery due to dissection. An attempted revascularization by percutaneous transluminal coronary angioplasty failed and the patient was then submitted to bypass surgery. We conclude that possible heart injury should be considered in patients with blunt chest trauma to lead them to adequate therapy.