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Biomedical subjects

N Zafrir

Publications and source records attributed to N Zafrir.

At least 37 records · Page 2Linked to original sources
PubMed1994

Isolated mid-anterior myocardial infarction: a special electrocardiographic sub-type of acute myocardial infarction consisting of ST-elevation in non-consecutive leads and two different morphologic types of ST-depression.

UNLABELLED: We describe eight patients with a distinct electrocardiographic pattern of anterior wall myocardial infarction characterized by three main features: (1) a pattern of 'transmural ischemia' (ST-elevation with positive T-wave) in non-consecutive leads: a VL and V2, and two different types of ST-depression; (2) a pattern of 'true reciprocal changes' (ST-depression and negative T-wave) in III and a VF; (3) a pattern of 'sub-endocardial ischemia' (ST-depression with positive T-wave) in V4-5, while ST in V3 was either isoelectric or depressed. We characterize the electrocardiographic features and correlate them with the echocardiographic, radionuclide, and angiographic data. All patients admitted to the coronary care unit from January 1990 to April 1992 with evolving acute myocardial infarction were evaluated prospectively. Patients whose admission electrocardiogram met the description above were included. The electrocardiographic evolution, echocardiographic, Technetium MIBI tomography, and coronary angiography are described. Of 471 patients with acute anterior wall myocardial infarction, admitted to the coronary care unit during the study period, eight patients met the inclusion criteria (1.7% of acute anterior wall myocardial infarction). Echocardiographic studies revealed mid-anterior hypokinesis in two patients, anterior and apical hypokinesis in one, and no wall motion abnormality in four patients. Technetium MIBI tomography, done in five patients, was consistent with mid-anterior or midanterolateral infarction without involvement of the septum or apex. Coronary angiography, performed in seven patients, demonstrated significant obstruction of the first diagonal branch in all of the patients. In four patients, the diagonal occlusion was the only significant coronary lesion in the left coronary artery. CONCLUSION: Most of the anterior myocardial infarctions also involve the septal and apical regions. Anterior wall myocardial infarctions limited to the mid-anterior or mid-anterolateral wall, without apical or septal wall involvement are relatively rare. This study describes a special electrocardiographic form of anterior wall acute myocardial infarction. This distinct electrocardiographic pattern represents true mid-anterior wall myocardial infarction, caused by occlusion of a first diagonal branch of the left anterior descending coronary artery. The septal and apical regions are not involved because the blood supply via the left anterior descending artery is not interrupted.

Coronary Angiography↗
PubMed1993

Prediction of arrhythmic events after acute myocardial infarction using two methods for late potentials recording.

One hundred consecutive patients recovering from an acute myocardial infarction underwent, prior to home discharge, signal-averaged electrocardiography (ECG), left ventriculography, and 24-hour Holter ECG recording. The signal-averaged ECG was recorded and analyzed using two procedures: the orthogonal bipolar XYZ lead configuration with a bidirectional filter; and a precordial unipolar lead configuration with a nonrecursive digital filter. An abnormal signal-averaged ECG was seen in 40% of patients with the XYZ system and in 30% of patients in the precordial method, abnormal ejection fraction (< 40%) in 24% of patients and high grade ectopy activity in 22%. During the 24-month follow-up period, 12 patients (12%) had an arrhythmic event defined as either sudden death (11 patients) or sustained ventricular tachycardia (1 patient). Neither the signal-averaged ECG with the XYZ configuration, the abnormal ejection fraction, nor the high grade ectopy were able to statistically predict a higher arrhythmic event rate. The signal-averaged ECG with the precordial configuration was able to statistically predict a higher arrhythmic event rate, P < 0.03; odds ratio = 3.96. The combination of the orthogonal XYZ configuration signal-averaged ECG with the ejection fraction (P < 0.01, odds ratio = 7.33), or with ejection fraction and Holter monitoring (P < 0.06, odds ratio = 6.17) was able to predict a higher arrhythmic event rate. The combination of the precordial configuration signal-averaged ECG with the ejection fraction (P < 0.002, odds ratio = 14.4), or with ejection fraction and Holter monitoring (P < 0.06, odds ratio = 10) was able to better predict a higher arrhythmic event rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The incidence of atrial arrhythmias during inferior wall myocardial infarction with and without right ventricular involvement.

The atrial arrhythmia profile during inferior wall acute myocardial infarction (AMI) has not been systematically examined with respect to right ventricular (RV) involvement. To this end, 62 consecutive patients with first inferior wall AMI and no other conditions known to increase susceptibility for rhythm disturbances were studied by 24-hour Holter monitoring during the first and tenth day of infarction. Based on radionuclear ventriculography performed on day 2 of infarction, patients were allocated to two groups: group A--36 patients (58%) with right ventricular ejection fraction (RVEF) less than 40% (mean +/- SD, 31 +/- 6%) and group B--26 patients (42%) with normal (greater than 40%) RVEF (mean +/- SD, 47 +/- 5%). There were no significant differences between the two groups with respect to age, sex, or left ventricular (LV) function. In the group as a whole, ectopic activity in the different categories of atrial arrhythmias was significantly higher during the first day than on the tenth day of infarction. Comparing the two groups, 33 patients (92%) in group A had a mean hourly frequency of one or more atrial premature contractions (APCs) during the first day of infarction compared with 18 patients (69%) in group B (p less than 0.001). Atrial and supraventricular tachycardia were recorded more frequently in group A patients (16 of 36 [44%] versus 8 of 26 [31%]) as well as atrial fibrillation (AF) (7 of 36 [19%] versus 1 of 26 [4%]). Quantitative analysis showed a similar trend for a higher rate of ectopic events in group A patients. Ectopic activity was neither influenced by LVEF nor by age or sex.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1992

S-T segment depression in right-sided precordial leads during acute inferior wall infarction.

Right-sided chest leads (V3-V4R) were recorded in the early stages of first inferior wall acute myocardial infarction (AMI) in 100 consecutive patients. Nine patients (9%) presenting with S-T segment depression (greater than 1 mm) in these leads were subsequently studied by echocardiography and radionuclear angiography. In this group, there were 5 patients with intact right ventricular (RV) function and 4 other patients with clinical findings compatible with RV infarction. We suggest that one should not rule out RV involvement when S-T segment depression rather than elevation is seen in the right precordial leads in the presence of inferior wall AMI. An individual assessment for RV infarction is recommended when this pattern is apparent on the ECG.

Aged↗
PubMed1990

The impact of right ventricular infarction on the prevalence of ventricular arrhythmias during acute inferior myocardial infarction.

To determine the impact of RV infarction on the prevalence and complexity of ventricular arrhythmias during inferior AMI, 57 patients with no prior MI were studied by 24-hour Holter monitoring on the first and tenth days of AMI. Based on radionuclear studies, patients were allocated into two groups: (1) group A, 21 patients (37 percent) with normal RVEF (greater than or equal to 40 percent); and (2) group B, 36 patients (63 percent) with depressed RVEF (less than 40 percent). There were no significant differences between the groups regarding age and LVEF. Values of RVEF were 47 +/- 6 percent and 31 +/- 6 percent, respectively (p less than 0.05). The RVEF had no influence on the prevalence and complexity of early and late arrhythmias. Stratification of patients in group B into two subgroups based on the extent of RV dysfunction did not reveal any differences in the occurrence of all forms of ectopy (when both groups were matched to group A). Therefore, patients with inferior AMI, with or without RV infarction, have a similar prevalence of arrhythmias. Ventricular ectopic beats may be related to the severity and spread of LV involvement, rather than to RV dysfunction.

Arrhythmias, Cardiac↗
PubMed1989

Evaluation of ventricular function with first-pass iridium-191m radionuclide angiocardiography.

Iridium-191m would appear to be a highly useful agent for first-pass radionuclide angiocardiography (FPNA), with its very short half-life (4.96 sec), dual photopeaks (65 and 129 keV), and high injectable activity levels (greater than 100 mc). In order to compare 191mIr FPNA to current methods used to define cardiac function, 20 patients referred for cardiac catheterization were studied. Count rate data, right ventricular (RV), and left ventricular ejection fraction (LVEF), LV and diastolic volume (EDV), and end diastolic long axis (AXIS) were evaluated. Count rate data using 191mIr FPNA was consistently better than similar data obtained by 99mTc FPNA. There were acceptable correlations between 191mIr and 99mTc FPNA RVEF (r = 0.848), 191mIr FPNA and contrast angiography LVEF (r = 0.944), LVEDV (r = 0.917), and LV AXIS (r = 0.866). The data thus suggests that 191mIr FPNA has great potential in the evaluation of cardiac function.

Adolescent↗
PubMed1988

Significance of the magnitude of a QS wave deflection in evaluating the uninvolved muscle in anterior wall myocardial infarction.

The significance of dynamic changes of the QS wave magnitude, as demonstrated in the precordial leads, within the natural evolution of acute anterior wall myocardial infarction (AAMI) was assessed in 25 patients within two weeks of their admission to the intensive cardiac care unit. Two sets of tests, including 12-lead electrocardiogram and a full radionuclear study, were performed in two time periods: (1) within the first 48 hours of admission; and (2) between the 12th and 15th day after admission. Comparison and correlation between the electrocardiographic data, QS waves in leads V2 and V3 and in V1 to V6 (sigma QV2-3 and sigma QV1-6), and radionuclear regional ejection fractions of the noninfarcted posterior muscle (inferior, infero-apical, and posterolateral regions and posterior index) were done. Significant linear correlations were demonstrated between the electrocardiographic variant differences in percentages (sigma QV2-3 and sigma QV1-6) and the radionuclear variant differences, especially the posterolateral and the infero-apical regions, as well as the posterior radionuclear index (r between 0.5 and 0.75; p less than 0.01). In addition, almost all of the patients who showed deepening of QS waves in the precordial leads also showed an increase in regional ejection fractions in uninvolved myocardium, and vice versa. It is concluded that the dynamic changes of the QS wave magnitude in the precordial leads within the evolution of acute anterior myocardial infarction well reflect the changes of the posterior noninfarcted muscle contraction and therefore offers a simple, inexpensive, and indirect electrocardiographic method for evaluating changes in contraction patterns of noninfarcted myocardium.

Electrocardiography↗
PubMed1987

Short- and long-term dobutamine treatment in chronic ischemic heart failure.

This study was undertaken in order to characterize the short-term (1 hour) and long-term (72 hours) effect of dobutamine on hemodynamic and regional ejection fraction parameters measured by radionuclear angiography in patients with chronic congestive heart failure due to coronary artery disease. Baseline hemodynamic and radionuclear parameters were measured and then intravenous dobutamine (8.5 mu/kg/min) was administered. The above parameters were determined again after 1 hour and 72 hours of continuous dobutamine administration. Sixty minutes (short-term) after dobutamine administration heart rate and cardiac index increased significantly (p less than 0.001 for both) and peripheral resistance decreased concomitantly (p less than 0.005). Global left ventricular ejection fraction (LVEF) as measured by multigated equilibrium nuclear angiography (MUGA) increased from 21.8 +/- 10.6% to 25 +/- 13.5 (p less than 0.02). Count-based mean regional ejection fraction in the septal, inferoapical, posterolateral (45 degrees left anterior oblique view) and inferior apical and anterolateral (30 degree right anterior oblique gated first pass) regions increased also. At 72 hours (long-term) after continuous dobutamine infusion, heart rate and cardiac index were still significantly higher and peripheral resistance lower than in the control study. However, global and count-based regional ejection fraction decreased to control values in the right anterior oblique view (first-pass analysis) and the left anterior oblique view (MUGA). Global LVEF measured in the right anterior oblique view by first-pass technique was significantly higher than control in the long-term study (23 +/- 9.7 vs. 27.8 +/- 2.4; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

A simplified QRS scoring system for the estimation of the severity of acute inferior wall myocardial infarction.

Electrocardiographic assessment of the R/Q wave ratio (lead 2) of patients with a first acute inferior wall myocardial infarction (IWMI) offers important indirect quantitative information regarding the severity and extent of the myocardial damage. Eighty-eight consecutive patients with IWMI were investigated by echocardiography and radionuclear angiography. After measuring the R/Q ratio in lead 2 during the ST-wave stabilized stage of myocardial infarction, patients were separated into three groups--group 1 with an R/Q ratio greater than 2; group 2 with an R/Q ratio between 1 to 2; and group 3 with an R/Q ratio less than 1. Utilizing the information thus gathered from the electrocardiogram (ECG) offers a simple and efficient method for early prognosis which merits further investigation.

Adult↗
PubMed1984

Left and right ventricular function in inferior acute myocardial infarction and significance of advanced atrioventricular block.

Of 139 consecutive patients with a first inferior acute myocardial infarction, 26 (19%) had advanced atrioventricular (AV) block and 113 (81%) did not. All were evaluated by 2-dimensional echocardiography (2-D echo) and radionuclide angiography. Patients with advanced AV block had lower radionuclide left ventricular (LV) ejection fraction (51 +/- 10 vs 58 +/- 11%, p less than 0.01), higher LV wall motion score on 2-D echo (5.6 +/- 2.6 vs 3.1 +/- 2.7, p less than 0.001), lower radionuclide right ventricular (RV) ejection fraction (32 +/- 15 vs 39 +/- 16%, p less than 0.001) and higher RV wall motion score on 2-D echo (3.4 +/- 1.7 vs 1.5 +/- 2, p less than 0.002) than did patients without AV block. The incidence rate of RV dysfunction was higher in patients with advanced AV block (78 vs 40%, p less than 0.02), and the mortality rate was also higher (although not significantly) in patients with advanced AV block (15 vs 6%). In conclusion, patients with inferior acute myocardial infarction and advanced AV block have larger infarct sizes (as seen on radionuclide angiography and 2-D echo) and lower RV and LV function than patients without AV block. This finding may explain the higher mortality rate observed in this group.

Adult↗
PubMed1983

Serial two-dimensional echocardiography in infective endocarditis of the pulmonic valve.

Infective endocarditis was diagnosed in a 15-yr-old patient following closure of a patent ductus arteriosus several weeks previously. Pulmonic valve vegetations were detected by both M-mode and two-dimensional echocardiograms. The serial echocardiographic examinations revealed the emergence of a vegetation on the pulmonic valve, a marked decrease in its size subsequent to pulmonary embolism, reemergence of a vegetation upon relapse of the disease and its resolution 4 mo later. The echocardiographic findings and their correlation to the various stages of the disease are described.

Adolescent↗
PubMed1981

Ventricular fibrillation complicating temporary ventricular pacing in acute myocardial infarction: significance of right ventricular infarction.

Five patients with acute myocardial infarction had ventricular fibrillation as a complication of indicated temporary pacing. All five patients had evidence of right ventricular infarction (three patients with postmortem confirmation). The presence of right ventricular infarction seems to be a contributing mechanism involved in the induction of ventricular fibrillation during temporary pacing for bradyarrhythmia complicating acute myocardial infarction.

Adult↗
PubMedDate not supplied

Prognostic utility of increased pulmonary thallium uptake in patients without ischemia.

BACKGROUND: Although the combination of increased pulmonary thallium uptake and ischemia has demonstrated prognostic utility, the value of pulmonary uptake independent of ischemia has not been evaluated critically. Accordingly, our purpose was to evaluate the prognostic utility of thallium lung uptake in patients who do not have stress-induced defects. METHODS AND RESULTS: We studied 184 patients who were divided into three groups. Patients with increased pulmonary uptake were grouped into either the normal perfusion (n = 48) or fixed defect (n = 44) scan group and were compared with a third group (n = 92) of control patients who had normal scans and no lung uptake. During a mean follow-up of 23 +/- 13 months, there were 13 cardiac events (death or myocardial infarction) and the incidence per year was 0.6%, 2%, and 12% in the control, normal, and fixed defect groups, respectively (p < 0.00001). Life table analysis demonstrated greater event-free survival rates in the control and normal groups compared with the group with fixed defects. A Cox regression analysis showed that the number of fixed defects (infarct segments) was the most important independent prognostic factor (p < 0.00001) for future cardiac events. CONCLUSION: In patients with increased pulmonary thallium uptake and no stress perfusion defects, the prognosis is similar to that of control patients. However, patients with infarct segments and lung uptake have a significantly worse prognosis.

Coronary Circulation↗