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No reports testing the efficacy of the use of the QT/RR ratio <1/2 for detecting a normal QTc interval were found in the literature. The objective of the present study was to determine if a QT/RR ratio <=1/2 can be considered to be equal to the normal QTc and to compare the QT and QTc measured and calculated clinically and by a computerized electrocardiograph. Ratios (140 QT/RR) of 28 successive electrocardiograms obtained from 28 consecutive patients in a tertiary level teaching hospital were analyzed clinically by 5 independent observers and by a computerized electrocardiograph. The QT/RR ratio provided 56 percent sensitivity and 78 percent specificity, with an area under the receiver operator characteristic curve of 75.8 percent (95 percentCI: 0.68 to 0.84). The divergence in QT and QTc interval measurements between clinical and computerized evaluation were 0.01 ± 0.03 s (95 percentCI: 0.04-0.02) and 0.01 ± 0.04 s (95 percentCI: -0.05-0.03), respectively. The QT and QTc values measured clinically and by a computerized electrocardiograph were similar. The QT/RR ratio <=1/2 was not a satisfactory index for QTc evaluation because it could not predict a normal QTc value.

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No reports testing the efficacy of the use of the QT/RR ratio <1/2 for detecting a normal QTc interval were found in the literature. The objective of the present study was to determine if a QT/RR ratio < or =1/2 can be considered to be equal to the normal QTc and to compare the QT and QTc measured and calculated clinically and by a computerized electrocardiograph. Ratios (140 QT/RR) of 28 successive electrocardiograms obtained from 28 consecutive patients in a tertiary level teaching hospital were analyzed clinically by 5 independent observers and by a computerized electrocardiograph. The QT/RR ratio provided 56% sensitivity and 78% specificity, with an area under the receiver operator characteristic curve of 75.8% (95%CI: 0.68 to 0.84). The divergence in QT and QTc interval measurements between clinical and computerized evaluation were 0.01 +/- 0.03 s (95%CI: 0.04-0.02) and 0.01 +/- 0.04 s (95%CI: -0.05-0.03), respectively. The QT and QTc values measured clinically and by a computerized electrocardiograph were similar. The QT/RR ratio < or =1/2 was not a satisfactory index for QTc evaluation because it could not predict a normal QTc value.

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The objective of the present investigation was to study the effects of a 60-s interval of venous congestion between two noninvasive measurements of arterial blood pressure (ABP) on the fluctuation of ABP, assessed by the standard deviation of the differences between two readings. ABP was measured in 345 successive patients, at rest, four times each. For 269 participants, one pair of readings was obtained with a 60-s interval and the other pair without an interval. For 76 patients, the first pair was read at the same interval, and the second pair had venous congestion interposed and there was no waiting interval. There was no increased ABP oscillation, either when there was no interval between ABP readings, or when venous congestion was interposed compared to pairs of ABP measurements performed with a 60-s interval. There was no increase in ABP oscillations when successive ABP readings were taken without an interval or even with venous congestion interposed. Contrary to the present belief, there seems to be no loss of reliability when blood pressure recordings are taken immediately one after another, in the clinical setting

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OBJECTIVE: To determine if the application of a continuous electrode paste band on precordial leads results in alteration of the electrocardiographic tracing as compared with an adequate amount of electrode paste, and if the former condition does not cause uniform morphologies from V1 to V6. METHODS: The amplitude and morphology of the electrocardiographic waves on the precordial leads in electrocardiographic tracings, which were performed with standard (control group) or excessive (continuous band) application of the electrode paste, were compared. RESULTS: None of the 106 patients studied showed uniformity of the QRS morphology from V1 to V6. The electrocardiographic alterations identified in the tracings performed with a continuous electrode paste band that showed statistical significance in relation to the control group were the following: inversion of the P wave in V1; inversion of the T wave in V1, V2, and V3; appearance of R' waves in V1 and V2; disappearance of S waves in V1; appearance of S waves in V5 and V6; alterations in the amplitude of almost all waves, in all leads. CONCLUSION: Application of a continuous electrode paste band in the precordial leads may cause significant alterations in the electrocardiographic tracing obtained.

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PURPOSE: To determine the type of cardiac disease causing left bundle branch block (LBBB) in Porto Alegre, Brazil, and to assess the role of associated left axis deviation (-30 degrees or more in the frontal plane) in order to identify a specific etiology of LBBB. METHODS: Through reports from the assistant physicians or through examination of the patients, the underlying heart disease in 264 cases of LBBB was assessed. The chi-square test was used to determine a possible association between left anterior hemiblock LBBB and one or more specific type of underlying heart disease. RESULTS: Systemic arterial hypertension (30.7%), ischemic heart disease (30.3%), valvar heart disease (8.7%), cardiomyopathies (7.5%), idiopathic degenerative disease of the conduction system (1.6%) and miscellaneous heart diseases (1.2%) were the underlying heart diseases. The presence of LBBB did not indicate any specific type of cardiac disease. CONCLUSION: The causes of LBBB in Porto Alegre are the same as reported in the international medical literature. Upward and leftward deviation (> or = -30 degrees) of QRS axis in the frontal plane did not show statistical significant association with any type of underlying cardiac disease.

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PURPOSE: To search for the existence and degree of correlation between total 12 lead ECG amplitude and the sum of RaVL + SV3 > 28 mm (for men) or > 20mm (for women) and left ventricular hypertrophy (LV mass calculated by echocardiography > 215g for both sexes). METHODS: ECG and echocardiograms of 227 consecutive patients were examined and submitted to statistical analysis searching for correlation between total 12 lead ECG amplitude and Cornell criteria and LV mass (ASE formula modified by Devereux). RESULTS: Patients had ischemic heart disease, hypertension, valvular disease, cardiomyopathy or other less common heart diseases, or had no cardiac illness at all. There was statistically significant association of total 12 lead amplitude > 120mm and Cornell criteria with LV mass > 215g (p = 0.02 and p = 0.01 respectively). Total ECG amplitude showed 74.3% sensitivity, 42.6% specificity, and 52.4% accuracy. Cornell criteria showed values of 37.8%, 82.7% and 68.7% respectively. CONCLUSION: Total 12-lead amplitude presented limited diagnostic performance for detecting LV hypertrophy, as well as did ECG Cornell criteria, although the latter was more specific and more accurate.

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PURPOSE: To evaluate changes in the electrocardiogram (ECG) with incorrect positioning of the chest lead for V1, placed in the second and third right intercostal spaces. METHODS: Two hundred and five patients were studied after a conventional ECG, with the record of tracings where the chest electrode for V1 was placed at the second and third right intercostal spaces at the right sternal border. These tracings were then compared with the former one and changes observed in the P wave, QRS complex and T wave registered and submitted to statistical analysis. Patients age ranged from 6 to 89 years, mean 46. Whites comprised 79%, black 6% and mulattos 15%. Women totalized 62% and men 38% of the sample. Clinical diagnosis were arterial hypertension (50%), no apparent cardiac disease (41%), coronary atherosclerotic heart disease (4%), mitral valve prolapse and other organic heart disease (5%). RESULTS: Negativation or accentuation of negative terminal forces of P wave were present in 84% of the patients, alterations in the QRS complex in 75% of the cases, and in the T wave in 66% of the cases, with confidence intervals of 0.7898 to 0.8901; 0.6907 to 0.8092; and 0.6163 to 0.7437, respectively. CONCLUSION: Important changes in the ECG record may occur with high probability if the chest electrode for lead V1 is placed above the standard place.

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PURPOSE: To compare the accuracy of left atrial enlargement (LAE) diagnosis made by electrocardiographic criteria with those obtained using M-mode echocardiography. METHODS: We studied 273 patients age 17 to 87 (mean 49) years, 115 men, white 95.5%, black 3.5% mulattos 1%, with or without heart disease of different etiologies. The ECG criteria studied were: a) P terminal force in V1 > or = 0.04 mmx s; b) Pt force in V1 duration > 0.04s; c) Pt force in V1 depth > or = 1 mm; d) P wave notching in D2 with interpeak distance > or = 40ms; f) presence of atrial fibrillation. The gold-standard for LAE was left atrial dimension > 40 mm obtained by echocardiography. RESULTS: The percentage of correct diagnosis were: atrial fibrillation (88%), Morris index (75%), PtfV1 negativity > or = 1 mm (74%), notched P wave in D2 with interpeak distance > or = 0.04 s (70%), PtfV1 with duration > 0.04 s (64%) and P wave duration in D2 > 0.11s (46%). CONCLUSION: Conventional ECG has limited value for detecting LAE. A higher correlation was found between atrial fibrillation and changes in P wave in V1 and the echocardiographic LAE.

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Os autores fazem breves comentarios sobre alguns aspectos praticos de deteccao e do manejo da hipertensao arterial sistemica essencial

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