ECG Variables Research Articles

Atrial fibrillation after coronary artery bypass surgery: P wave signal averaged ECG, clinical and angiographic variables in risk assessment

Background: Atrial fibrillation (AF) is a commonly encountered arrhythmia and occurs in up to 40% of patients after coronary artery bypass surgery (CABG). The preoperative signal averaged ECG (SAECG) P wave may be useful indicator of AF after CABG. We prospectively analyzed the predictive value of SAECG P wave compared to clinical variables. Methods: Fifty-three patients with coronary artery disease undergoing first elective CABG were enrolled. All patients had P wave specific SAECG, standard 12 lead ECG, ejection fraction and left atrial posteroanterior diameter from the echocardiogram within the 24 h before surgery. From the SAECG P wave, filtered P wave duration was measured. Lead II P wave duration, left atrial enlargement and left ventricular hypertrophy were determined from standard ECG. Patients were continuously monitored during their postoperative period and serial ECGs were taken. Results: During an observation period of up to 16 days, 19 (35.8%) patients developed AF 2.8±1.3 days after CABG. Patients with AF more often had left atrial enlargement (LAE) on ECG ( P=0.041) and right coronary artery (RCA) lesion ( P=0.0034). The filtered P wave duration on the SAECG was significantly longer in the AF patients than those without AF (129.7±13.2 ms versus 113.9±9.0 ms, P=0.001). Logistic regression analysis identified independent predictors, estimated adjusted relative risk (95% confidence interval) of AF: with LAE, the relative risk was 2.72 (1.13–5.82), RCA lesion, the relative risk was 3.06 (1.45–6.45) and SAECG P wave duration >122.3 ms, the relative risk was 4.58 (2.11–9.97). The occurrence of AF was predicted by electrocardiographically determined left atrial enlargement with a sensitivity of 36%, specificity of 88%, positive predictive accuracy of 63%, negative predictive accuracy of 71%. If presence of right coronary artery lesion was evaluated these values were 63%, 79%, 63%, 79% subsequently. P wave duration >122.3 ms had a sensitivity of 68%, specificity of 88%, positive predictive accuracy of 76%, negative predictive accuracy of 83%. If both P wave >122.3 ms and presence of right coronary artery lesion were combined, these values were 47%, 94%, 81%, 76% subsequently. Conclusion: The predictors of AF after CABG were left atrial enlargement on standard 12 lead ECG, RCA lesion and SAECG P wave duration. Among these predictors, SAECG P wave duration was the best predictor of AF after CABG.

Standard 12‐Lead and 24‐Hour Ambulatory Electrocardiographic Abnormalities in Survivors of Tachyarrhythmic Cardiac Arrest

BackgroundThe aim of the present work was to compare the accuracies of variables obtained from a standard 12‐lead ECG and a 24‐hour ambulatory ECG in discriminating between patients with and patients without tachyarrhythmic cardiac arrest after a previous myocardial infarction.MethodsQTc interval and QTc dispersion measured from a 12‐lead ECG and an analysis of ventricular premature depolarization, nonsustained ventricular tachycardia, and heart rate variability from a 24‐hour ECG were compared in survivors of tachyarrhythmic cardiac arrest (n = 57) and in postmyocardial infarction control patients without a history of arrhythmic events and an arrhythmic‐free survival in a 2‐year follow‐up (n = 57). The groups were matched for age, gender, left ventricular ejection fraction, and the usage of beta‐blocking medication.ResultsQTc dispersion (103 ± 44 vs 71 ± 32 ms, P < 0.001) and the QTc interval maximum, defined as the longest QTc interval in any of the 12 leads of ECG (508 ± 52 vs 459 ± 42 ms, P < 0.001), were longer in the cardiac arrest survivors than in the controls. The standard deviation of R‐R intervals, a measure of heart rate variability, was lower in the cardiac arrest survivors (86 ± 38 vs 108 ± 32 ms, P < 0.001), who had also experienced more commonly ≥; 10 ventricular premature depolarizations/hour (61% vs 35%, P < 0.01) on the 24‐hour ECG. In a stepwise multiple regression analysis, the QTc interval maximum and the standard deviation of R‐R intervals were the most significant independent variables that differed between the groups (P = 0.0002, P = 0.0023, respectively). Their combination yielded a high positive predictive accuracy (91%).ConclusionsSimple measurement of the maximum QTc interval from a standard 12‐lead ECG performs equally well or even better than the other more time‐consuming 12‐lead or 24‐hour ambulatory ECG variables in discriminating between patients with a history of tachyarrhythmic cardiac arrest and patients without a history of ventricular tachyarrhythmias after a remote myocardial infarction.

Electrocardiographic changes during low-dose, short-term therapy of cutaneous leishmaniasis with the pentavalent antimonial meglumine.

The pentavalent antimonial (Sb5+) meglumine is the drug of choice for the treatment of cutaneous leishmaniasis (CL) in Brazil. Although the cardiotoxicity of high-dose, long-term Sb5+ therapy is well known, the use of low-dose, short-term meglumine has been considered to be safe and relatively free from significant cardiac effects. In order to investigate the cardiotoxicity of low-dose, short-term therapy with meglumine in cutaneous leishmaniasis, 62 CL patients treated with meglumine were studied. A standard ECG was obtained before and immediately after the first cycle of treatment (15 mg Sb5+ kg-1 day-1). The electrocardiographic interpretation was carried out blindly by two investigators using the Minnesota Code. There were no significant differences in qualitative ECG variables before and after meglumine treatment. However, the corrected QT interval was clearly prolonged after antimonial therapy (420.0 vs 429.3 ms, P < 10(-6)). QTc augmentation exceeded 40 ms in 12 patients, 7 of whom developed marked QTc interval enlargement (500 ms) after meglumine therapy. This previously unrecognized cardiac toxicity induced by short-term, low-dose antimonial therapy has potentially important clinical implications. Since sudden death has been related to QTc prolongation over 500 ms induced by high-dose antimonial therapy, routine electrocardiographic monitoring is probably indicated even in CL patients treated with short-term, low-dose meglumine schedules. Until further studies are conducted to establish the interactions between pentavalent antimonials and other drugs, special care is recommended when using meglumine in combination with other medications, in particular with drugs that also increase the QTc interval.

Assessment of QT dispersion for prediction of mortality or arrhythmic events after myocardial infarction: results of a prospective, long-term follow-up study.

Risk stratification by means of analysis of QT dispersion (QTD) in the 12-lead surface ECG is under intense investigation in various patient populations. The aim of the present prospective study was to evaluate the prognostic value of QTD and other ECG variables reflecting dispersion of ventricular repolarization in comparison with established risk stratifiers during long-term follow-up in a large cohort of post-myocardial infarction patients treated according to contemporary therapeutic guidelines. In 280 consecutive infarct survivors, the 12-lead ECG was optically scanned and digitized for analysis of QTD (QTmax-QTmin) and 25 other repolarization variables, including recently developed and validated parameters such as the T peak-to-T end interval and the area under the T wave. In addition, a variety of established risk stratifiers were assessed. After a mean follow-up period of 32+/-10 months, 30 patients reached one of the prospectively defined study end points (death, ventricular tachycardia, or resuscitated ventricular fibrillation). Comparisons between event and nonevent patients by means of Kaplan-Meier event probability analyses revealed that none of the ECG dispersion variables were of discriminative value. In contrast, variables such as left ventricular ejection fraction (P=0.007), mean 24-hour heart rate (P=0.022), or heart rate variability (P=0.007) proved to be potentially useful risk stratifiers in this patient population. On multivariate analysis, only LVEF, heart rate variability, and a history of thrombolysis were independent predictors of outcome. Determination of QTD from the surface ECG even when performed with the best available methodology failed to predict subsequent risk in this large series of infarct survivors.

Lidocaine increases the ventricular fibrillation threshold during bupivacaine-induced cardiotoxicity in pigs

Ventricular fibrillation (VF) is a cause of death in bupivacaine-induced cardiovascular toxicity. We have examined the therapeutic effects of lidocaine on the threshold for bupivacaine-induced VF in in situ beating swine hearts. Twenty-four animals were allocated to one of three groups: 0.25% bupivacaine, 1% lidocaine or 0.25% bupivacaine with 1% lidocaine were infused into the left anterior descending coronary artery in increasing doses of 0, 1, 2, 4, 8 and 16 ml h-1 for 15 min, respectively. ECG and haemodynamic variables were monitored continuously during infusion. Regional myocardial function in the area supplied by the left anterior descending coronary artery was assessed using the sonomicrometry technique. VF did not occur in the lidocaine group. VF developed at higher infusion rates in animals given bupivacaine with lidocaine (in one animal at an infusion rate of 8 ml h-1 and in seven at 16 ml h-1) compared with animals given bupivacaine alone (in one at an infusion rate of 4 and in seven at 8 ml h-1). Although regional myocardial function decreased with increases in the infusion rate in each group, the depressant effects of the bupivacaine solution (medial inhibitory infusion rate of systolic shortening: IR50 = 2.43 (0.43) ml h-1) were significantly greater than those of the lidocaine solution (IR50 = 5.83 (0.87) ml h-1), but did not differ from those of the bupivacaine with lidocaine solution (IR50 = 3.54 (0.56) ml h-1). This study indicates that a combination of lidocaine and bupivacaine increased the threshold for bupivacaine-induced VF without further depressing myocardial contractility.

Validation of ECG Variables of Dispersion of Ventricular Repolarization by Direct Myocardial Repolarization Measurements in the Human Heart

Validation of ECG Variables of Dispersion of Ventricular Repolarization by Direct Myocardial Repolarization Measurements in the Human Heart

Validation of ECG variables of dispersion of ventricular repolarization by direct myocardial repolarization measurements in the human heart

Validation of ECG variables of dispersion of ventricular repolarization by direct myocardial repolarization measurements in the human heart

Prognostic value of residual ischaemia assessed by exercise electrocardiography and dobutamine stress echocardiography in low-risk patients following acute myocardial infarction.

Risk stratification after uncomplicated myocardial infarction is major clinical problem. In particular, the prognostic value of residual inducible ischaemia is still controversial. We compared the relative prognostic value of exercise ECG and dobutamine stress echocardiography performed in the early post-infarction period. Four hundred and six patients (53 female) aged 57 +/- 9 years, undergoing maximal exercise ECG and dobutamine stress echocardiography within 10 days of an uncomplicated myocardial infarction off therapy, were prospectively followed-up for 8.8 months. Age, sex, diabetes, smoking habit, hypertension, dyslipidaemia, infarct location, thrombolysis and resting wall motion score index were taken into account among clinical variables. Prognostic correlations were made vs spontaneous events (cardiac death, non-fatal reinfarction and unstable angina requiring hospitalization) whilst patients undergoing revascularization (by means of percutaneous transluminal coronary angioplasty or coronary artery bypass surgery) at the time of the procedure were censored. One hundred and twenty-seven events occurred during the follow-up: 41 (10%) were spontaneous (five deaths, 12 reinfarctions and 24 unstable angina) and 86 procedural (27 angioplasty and 59 bypass surgery). Spontaneous events were not predicted by any clinical, exercise ECG or dobutamine stress echocardiography variable, but the negative predictive value of both tests was excellent (91% and 90% respectively). With a multivariate Cox analysis, male gender, positive low-workload (< 100 W) exercise ECG (P < 0.0001), positive low-dose dobutamine stress echocardiography (P < 0.0001) and rest-stress wall motion score index variation (P < 0.001) were found to predict cumulative cardiac events with an independent and additive value. Dobutamine stress echocardiography was significantly more sensitive (P < 0.05) and less specific (P < 0.01) in predicting the outcome of patients with anterior infarction, whilst exercise ECG was significantly more sensitive (P < 0.05) in patients with non-Q wave infarction. (1) Spontaneous events are poorly predicted by provocative tests in low-risk patients after uncomplicated myocardial infarction. (2) However, both exercise ECG and dobutamine stress echocardiography can predict a favourable outcome with a very high negative predictive value. (3) Dobutamine stress echocardiography should be considered a secondary option in cases where the exercise ECG is equivocal or when the location of ischaemia is a relevant issue. (4) The possibility that the two tests have a differential utility depending on the infarct location and type (Q wave vs non-Q wave) may be clinically relevant and deserves further evaluation.

Evaluation of QT interval length, QT dispersion and myocardial m-iodobenzylguanidine uptake in insulin-dependent diabetic patients with and without autonomic neuropathy.

1. An association has been reported between QT interval abnormalities and cardiovascular autonomic neuropathy in diabetic patients. The QT interval abnormalities reflect local inhomogeneities of ventricular recovery time and may be related to an imbalance in cardiac sympathetic innervation. Sympathetic innervation of the heart can be visualized and quantified by single-photon emission-computed tomography with m-[123I]iodobenzylguanidine. In this study we evaluated cardiac sympathetic integrity by m-[123I]iodobenzylguanidine imaging and the relationship between both QT interval prolongation and QT dispersion from standard 12-lead ECG variables and m-[123I]iodobenzylguanidine uptake in insulin-dependent diabetic patients. 2. Three patient groups were studied, comprising six healthy control subjects, nine diabetic patients without cardiovascular autonomic neuropathy (CAN-) and 12 diabetic patients with cardiovascular neuropathy (CAN+). Resting 12-lead ECG was recorded for measurement of maximal QT interval and QT dispersion. The QT interval was heart rate corrected using Bazett's formula (QTc) and the Karjalainen approach (QTk). Quantitative measurement (in counts/min per g) and visual defect pattern of m-[123I]iodobenzylguanidine uptake were performed using m-[123I]iodobenzylguanidine single-photo emission-computed tomography. 3. Global myocardial m-[123I]iodobenzylguanidine uptake was significantly reduced in both diabetic patient groups compared with control subjects. The visual defect score of m-[123I]iodobenzylguanidine uptake was significantly higher in CAN+ diabetic patients than in control subjects and in CAN- patients. This score was not significantly different between control subjects and CAN- patients. QTc interval and QT dispersion were significantly increased in CAN+ diabetic patients as compared with control subjects (QTc: 432 +/- 15 ms versus 404 +/- 19 ms, P < 0.05; QT dispersion: 42 +/- 10 versus 28 +/- 8 ms, P < 0.05). QT dispersion was also significantly longer in CAN- diabetic patients than in control subjects (41 +/- 9 ms versus 28 +/- 8 ms, P < 0.05). QTc interval was significantly related to global myocardial m-[123I]iodobenzylguanidine uptake and defect score in diabetic patients (r = -0.648, P < 0.01, and r = 0.527, P < 0.05, respectively). There was no correlation between QT dispersion and both m-[123I]iodobenzylguanidine uptake measures. 4. In conclusion, these findings suggest that m-[123I]iodobenzylguanidine imaging is a valuable tool for the detection of early alterations in myocardial sympathetic innervation in long-term diabetic patients without cardiovascular autonomic neuropathy. Insulin-dependent diabetic patients with cardiovascular autonomic neuropathy have a delayed cardiac repolarization and increased variability of ventricular refractoriness. The cardiac sympathetic nervous system seems to be one of the determinants of QT interval lengthening, but does not appear to be involved in dispersion of ventricular recovery time. It is assumed that QT dispersion is based on more complex electrophysiological mechanisms which remain to be elucidated.

Value of QT dispersion in the interpretation of exercise stress test in women.

Exercise testing in women is associated with a high incidence of false-positive ECG changes and should be combined with an imaging study. The QT dispersion (QTD), recorded as the difference between maximum and minimum QT intervals on a 12-lead ECG, is sensitive to myocardial ischemia and may improve the accuracy of exercise testing in women. Exercise ECGs were analyzed in 64 women who had undergone exercise ECG and coronary angiography for clinical indications: 20 patients with normal exercise stress test and nonsignificant (< or = 50% diameter narrowing of a major epicardial coronary artery) coronary artery disease (CAD) on angiography (true-negative; TN group), 20 patients with positive exercise stress tests (> or = 1 mm ST-segment depression or reversible perfusion defects) and significant CAD (true-positive; TP group), and 24 patients with positive exercise stress tests but no significant CAD (false-positive; FP group). The exercise QTD was 45+/-15 ms in TN, 80+/-23 ms in TP (P<.0001 versus TP), and 41+/-14 ms in FP (P=NS versus TN and <.0001 versus TP) groups. A stress QTD of > 60 ms had a sensitivity of 70% and specificity of 95% for the diagnosis of significant CAD compared with 55% (P<.05) and 63% (P<.01), respectively, for > or = 1 mm ST-segment depression during stress. When QTD of > 60 ms was added to ST-segment depression as a condition for positive test, the specificity increased to 100%. Exercise QTD is an easily measurable ECG variable that significantly increases the accuracy of exercise testing in women.

Reproducibility of the ST-segment depression/heart rate analysis of the exercise electrocardiographic test in asymptomatic middle-aged population

The findings of this study on reproducibility of the exercise ECG variables in 61 asymptomatic middle-aged subjects give further support to the clinical utility of the ST HR hysteresis. The results also indicated that the observed change in the exercise ECG variable between repeated measurements must be large to make the clinician confident that a real diagnostic change has occurred.

Changes in cardiac output during air ambulance repatriation.

To measure, with the use of suprasternal Doppler ultrasound, the hemodynamic changes in patients and volunteers during air ambulance repatriation. Unblinded prospective observational study. Chartered air ambulances for the international repatriation of patients. Six medical crew members and seven patients transported back to hospitals in the UK. The measurement of non-invasive blood pressure, ECG, heart rate, oxygen saturation and hemodynamic variables with suprasternal Doppler. There was a drop in systolic and mean arterial blood pressure in the patient's group once in the air. Oxygen saturation dropped in both groups once at cruising altitude. Heart rate remained unchanged. Stroke distance and minute distance increased significantly in the patient's group and non-significantly in the volunteers. Peak velocity increased significantly in the patient's group. There was an overall reduction of systemic vascular resistance during take off and once at cruising altitude. Hemodynamic changes happen during air ambulance transportation in fit and healthy volunteers and patients alike. These may be due to a combination of hypobaric hypoxia and gravitational forces. It is necessary to establish if these changes have short- or long-term effects in the critically ill.

Late Potentials Detected by Digital Holter ECG: Reproducibility, Lead Systems, and Effects of Physical Activity

Background: We sought to assess reproducibility, effects of various lead systems, and influence of physical activity on the results of signal‐averaged ECG obtained from the digital Holter system. Late potentials are routinely recorded using specially designed electrocardiographic devices. It has been shown recently that late potentials can also be recorded and analyzed from Holter tapes, which enables to examine possible dynamic changes of late potentials in relation to transient ischemia and spontaneous ventricular arrhythmias. However, there are some technical limitations of the signal‐averaged ECG analysis from Holter tapes that may be overcome by the use of digital, solid‐state Holter recorders where the ECG signal is acquired directly by the computer system and analyzed in real time.Methods: The signal‐averaged ECG was recorded at rest from XYZ leads and from lead system suggested by the manufacturer (Holter leads), and during moderate physical activity in 34 postin‐farction patients, using a new solid‐state Holter recorder. From each of these 20 minutes of recording, four consecutive ECG segments, lasting 5 minutes, were averaged, combined into vector magnitude, and analyzed using a Butterworth bidirectional filter between 40 and 250 Hz.Results: Reproducibility of signal‐averaged ECG was high; the P values (ANOVA) ranged from 0.93–0.99. Of the individual signal‐averaged ECG variables, reproducibility of the total QRS duration was superior to that of the terminal QRS measurements (the standard deviations of the mean relative errors were 6.3% vs 22.3% and 24.4%, respectively). There were no signifcant differences in signal‐averaged ECG variables when results obtained using orthogonal XYZ leads were compared with those obtained from Holter leads. Modest physical activity (slow walk) did not alter significantly signal‐averaged ECG variables. The values of the total QRS duration were more consistent than the terminal QRS measurements when two lead confgurations and recordings obtained during rest and physical activity were compared.Conclusions: Reproducibility of signal‐averaged ECG analysis obtained from a digital Holter system is high, the results are similar using XYZ or Holter leads, and the signal‐averaged ECG can be recorded and analyzed during minor physical activity.

Gender-dependent variability of signal-averaged electrocardiogram in acromegaly.

Ventricular late potentials are obtained by signal-averaged surface electrocardiography. Late potentials in normal subjects may be influenced by physiological elements such as gender, height and body mass index. Considering that growth hormone (GH) hypersecretion is able to markedly alter different anthropometric variables, we studied the relation between these elements and the late potentials of 22 acromegalic patients. Males registered higher absolute QRS duration and LAS40 (low-amplitude signal) and, on the opposite, lower RMS40 (root mean square) in comparison to females; QRS duration and LAS40 seem to depend, however, on the different anthropometric variables, since their normalization with height and lean body mass (LBM) abolishes gender-dependent differences. On the contrary, the persistence, among males, of lower RMS40 in respect to females even after normalization for height, LBM and insulin-like growth factor 1 values makes it likely that the latter ECG variable is independent of the anthropometric ones and from the disease's activity. Moreover, males appear to be more vulnerable to GH heart-harming activity.

Cardiopulmonary effects of medetomidine in heartworm-infected and noninfected dogs

Summary Medetomidine, an investigational drug indicated for clinical use as a short-term chemical restraint in dogs, was evaluated for its cardiopulmonary effects, in 10 naturally heartworm-infected (HW+) and 10 noninfected (hw−) Beagles. The drug was randomly administered IV (30 μg/kg of body weight) and IM (40 μg/kg) in single injections to all dogs. Heart rate, respiratory rate, ecg, blood gas tensions, blood pH, central venous and arterial pressures were measured at 0, 15, 30, 60, 90, 120, and 180 minutes. Medetomidine induced an immediate significant (P ≤ 0.001) increase in mean arterial blood pressure followed by decreased blood pressure that remained below normal throughout the study in both groups, irrespective of route of administration. Medetomidine increased central venous pressure, over time, for both groups and both routes of administration. Heart and respiratory rates were significantly (P ≤ 0.001) decreased after medetomidine administration and remained reduced for the duration of the study in all dogs. The ecg variables were not significantly different between groups or between routes of administration. The HW+ dogs tended to have higher mean Pao2 than did HW− dogs at several postinjection determination times, particularly when the drug was administered IM. The Pao2; decreased during the first 30 minutes in both groups and tended to increase gradually thereafter. The pH decreased over time for both groups and both routes. A significant (P ≤ 0.05) decrease in pH was seen in the HW− dogs, compared with HW+ dogs at each measuring time for both routes. The Paco2 did not significantly change for groups or routes. In general, bradycardia was the predominant cardiovascular effect seen after medetomidine administration in all dogs, irrespective of route. Lowering of blood pressure and heart rate (after a transient blood pressure increase) was synchronized with sedation in these dogs. The overall clinical response with regard to cardiopulmonary effects in HW+ dogs was similar to that in HW− dogs.

Electrocardiographic characteristics indicating a risk of irreversibly impaired myocardial function in chronic aortic regurgitation

In order to define which of selected ECG variables could indicate irreversibly impaired myocardial function in chronic aortic regurgitation 54 patients were stratified according to normal (≥50%; Group A, n = 41) or subnormal radionuclide left ventricular ejection fraction (LVEF < 50%; Group B, n = 13) late after aortic valve replacement. Preoperatively, Group B patients had a significantly greater QRS duration, greater R-peak time (RPT) prolongation in I, V 5 or V 6, greater RPT relative to the S-peak time of the maximum S in V 1, V 2 or V 3 (R-peak delay) and a greater negative T-wave in I or V 6, as compared with Group A. These ECG variables together with preoperative angiocardiographic LVEF and end-systolic volume index were subjected to stepwise linear discriminant analysis. The maximum RPT, angio-LVEF and the maximum RPT relative to the S-peak time of the maximum S in V 1, V 2 or V 3 emerged as the most promising variables. Of of Group A patients 82.9% and 84.6% of Group B patients were correctly classified by the three variables. If applied separately, APT prolongation or the presence of the R-peak delay in the left-sided leads, although less sensitive, have reasonably high specificity as risk indicators of irreversibly impaired chamber function, their positive predictive value being 60 and 62.5%, respectively. In conjunction with preoperative LVEF the diagnostic contribution of the two ECG variables amounts to the greatest overall separation of postoperatively preserved from irreversibly impaired systolic function.

Electrocardiographic Changes in Pericardial Effusion

To investigate the association between ECG changes and the presence of pericardial effusion. The ECG changes associated with pericardial effusion described in textbooks are based only on small series of human cases and data from animals. These changes include low QRS voltage, electrical alternans, P wave changes, and T wave inversion. All patients who had undergone 2 temporally separate echocardiographic and ECG examinations, with 1 echocardiographic examination indicating the presence and the other indicating the absence of pericardial effusion were identified (n = 46). These patients were age- and sex-matched to 46 patients without effusion (control subjects). Pericardial effusion was classified echocardiographically as small (n = 28), moderate (n = 13), and large (n = 5). The ECG variables were independently measured by two investigators blinded to effusion status. When 2 temporally separate ECGs for 46 patients were obtained in a repeated-measures fashion (1 obtained during the absence and the other during the presence of effusion; median time interval, 1.24 months), only the mean heart rate in patients with sinus rhythm (98 beats per minute increasing to 106 beats per minute) and the percentage of patients with QRS voltage of less than 0.5 mV (10 percent increasing to 22 percent) were associated with the development of effusion. A weak correlation (r = 0.296) was noted between QRS voltage and effusion size. Electrical alternans occurred only in one of the five patients with a large effusion but in no others. In addition, when the ECGs indicating effusion from the 46 patients were compared with the ECGs from their age- and sex-matched control subjects, differences in heart rate (106 beats per minute vs 80 beats per minute, respectively) and small changes in QRS voltage were associated with effusion status. No ECG variable was sensitive for the detection of pericardial effusion. In both repeated-measures and case-control comparisons, ECG findings are two few, subtle, insensitive, and nonspecific to be useful as indicators of the presence of pericardial effusion.

Myocardial uptake and release of lactate after high dose neurolept endotracheal intubation in coronary surgery.

To evaluate the relationship between the hemodynamic and ECG variables used in routine surveillance of coronary surgery and myocardial lactate metabolism, 23 middle-aged, male, beta 1-blocked patients about to undergo coronary surgery were monitored before and after endotracheal intubation with high dose (30 micrograms/kg) fentanyl-midazolam anesthesia. The induction of anesthesia was followed by a mean arterial pressure decrease (from 98 +/- 4 to 76 +/- 3 mm Hg) and heart rate increase (from 53 +/- 3 to 66 +/- 2 beats/min). After intubation the hemodynamic variables were stable except for a further, transient increase in heart rate (to 69 +/- 2 beats/min). The myocardial uptake of lactate decreased after intubation, from 48 +/- 5 mumol/min to a lowest level of 24 +/- 3 mumol/min. A lactate release was exhibited in 7/23 patients (30%). No ST-segment changes were observed. The correlation between the myocardial lactate uptake/release and hemodynamic or ECG variables was unimpressive or non-existent (r < or = 0.20). Thus, a reduced uptake and even a release of lactate occurred irrespective of the ST-segment, heart rate, or systemic or pulmonary artery pressures. In conclusion, endotracheal intubation in patients with coronary disease was consistently (17/23 patients) followed by a reduced myocardial uptake of lactate, in spite of high dose neurolept anesthesia and beta 1-blockade. This metabolic event was not consistently related to hemodynamic changes.

Ten-year experience with mitral valve replacement in the elderly

Limited data are available on mitral valve replacement in the elderly patient. Therefore we report our 10-year experience including predictors of perioperative mortality and subsequent long-term cardiac mortality in elderly patients with mitral valve replacement compared to younger patients. Of the 126 consecutive patients with mitral valve replacement, 26 were older (77 ± 4, group 1) and 100 were younger (62 ± 9, group 2) than 70 years. Bioprostheses were used more frequently in patients in group 1 (65% vs 7%, p < 0.0001). Of the 21 clinical, ECG, hemodynamic, and angiographic variables studied, patients in group 1 had higher pulmonary artery systolic pressure (57 ± 15 vs 48 ± 19, p < 0.05), fascicular block on ECGs (70% vs 33%, p < 0.005), and greater pump time on cardiopulmonary bypass (160 ± 75 vs 120 ± 50 minutes, p < 0.025). A trend toward a higher perioperative mortality rate was also seen in group 1 (27% vs 12%, p = 0.058). Predictors of perioperative mortality by multivariate analysis were the presence of aortic calcification and prolonged pump time on cardiopulmonary bypass in group 1 and coronary artery disease, female sex, elevated mean pulmonary artery pressure, and postoperative complete atrioventricular block in group 2. During a mean 4-year follow-up period, cardiac mortality and total mortality rates were 42% and 54%, respectively, for group 1 compared to 24% and 35%, respectively, for group 2. Predictors of cardiac mortality by multivariate analysis were aortic calcification, pacemaker implantation, elevated mean pulmonary artery pressure, decreased left ventricular ejection fraction, and smaller prosthetic valve size in group 1 and female sex, coronary artery disease, perioperative atrioventricular block, age, and elevated mean pulmonary artery pressure in group 2. Thus elderly patients with mitral valve replacement have higher perioperative mortality and subsequent cardiac mortality than younger patients. Further studies comparing mitral valve replacement with valve repair and valvuloplasty seem indicated.

Nortriptyline treatment of depressed cardiac transplant recipients

The safety of tricyclic antidepressants in cardiac transplant recipients has not been established. The author used nortriptyline to treat major depressive episodes in eight cardiac transplant recipients. Nortriptyline therapy was associated with increased QRS interval and heart rate but did not significantly affect other hemodynamic or ECG variables or cyclosporine dose requirements. It appears that nortriptyline may be used safely in depressed cardiac transplant patients.