Journal of the American College of Cardiology
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J. Am. Coll. Cardiol. · Mar 1988
Randomized Controlled Trial Comparative Study Clinical TrialSequential pulse defibrillation in humans: orthogonal sequential pulse defibrillation with epicardial electrodes.
A newly described sequential pulse technique, using four mesh electrodes positioned to approximate a true orthogonal system around the heart, was compared with a single pulse system using two of these same electrodes, which were located in positions that would be used for an automatic implantable defibrillator. The influence of electrode size was also assessed. The minimal energy necessary for defibrillation (defibrillation threshold) was determined intraoperatively in 21 volunteer patients undergoing accessory pathway ablation of Wolff-Parkinson-White syndrome. ⋯ Defibrillation thresholds were determined in three groups of patients: 1) those with four small mesh electrodes (6 cm2), 2) those with two small and two large (13 cm2) mesh electrodes, and 3) those with four large mesh electrodes. In all cases, the average minimal energy needed for sequential pulse defibrillation was less than that required for single pulse defibrillation in the same patients with the same electrodes (four small, 24.8 +/- 24.7 J single versus 6.7 +/- 8.3 J sequential; two small plus two large, 11.4 +/- 15.0 J single versus 2.7 +/- 1.4 J sequential; four large, 8.1 +/- 5.3 J single versus 3.9 +/- 2.6 J sequential). Using the 6 cm2 electrodes for single pulse defibrillation energies delivered at greater than 45 J in two patients failed to defibrillate the heart.(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Am. Coll. Cardiol. · Mar 1988
Sonospirometry: a new method for noninvasive estimation of mean right atrial pressure based on two-dimensional echographic measurements of the inferior vena cava during measured inspiration.
A noninvasive method of estimating mean right atrial pressure would be useful in evaluating hemodynamics and calculating pulmonary pressures by Doppler echocardiography. An electronic pressure gauge was built and tested for measurement of inspiratory pressures during two-dimensional echocardiography to quantitate the diameter of the inferior vena cava. Thirty-one studies were made in 27 alert, informed, consenting patients with an in-place pulmonary artery catheter having right atrial ports. ⋯ In this segment, the inspiratory pressure required to decrease the inferior vena cava diameter to greater than or equal to 85% of the difference between its maximal (suspended full inspiration) and minimal (over the entire inspiratory maneuver) values was similar or equal to the mean right atrial pressure (measured from the pulmonary artery catheter) (r = 0.87, SEE = 2.9 mm Hg). Minimal inferior vena cava diameter was directly related to mean right atrial pressure (r = 0.56); the minimal to maximal inferior vena cava diameter ratio was inversely related to mean right atrial pressure (r = -0.57). Maximal inferior vena cava diameter and the absolute (measured) amount of inferior vena cava diameter decrease correlated weakly with mean right atrial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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J. Am. Coll. Cardiol. · Feb 1988
Ectopic automatic atrial tachycardia in children: clinical characteristics, management and follow-up.
Ectopic automatic atrial tachycardia, an uncommon type of supraventricular tachycardia in children and adults, has been reported to be resistant to medical therapy, and surgical or cryoblation has been recommended. This report describes 10 infants and children (median age 6 months; range birth to 7.5 years) with automatic atrial tachycardia and their management and follow-up. Digoxin alone was unsuccessful in controlling tachycardia in all 10 patients but decreased the tachycardia rate by 5 to 20% in 8. ⋯ Thus, intravenous propranolol and amiodarone were effective in acutely suppressing automatic ectopic atrial tachycardia and predicted the response to long-term oral therapy. One patient had persistent tachycardia after surgical ablation of the high right atrial ectopic focus, and another patient had unsuccessful catheter ablation of the high right atrial ectopic focus (25 J). During follow-up (10 to 28 months), ectopic atrial tachycardia resolved completely in four patients and was well controlled in four patients.
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J. Am. Coll. Cardiol. · Jan 1988
Noninvasive evaluation of aortic stenosis severity utilizing Doppler ultrasound and electrical bioimpedance.
Aortic valve area was calculated noninvasively in 30 patients with aortic stenosis undergoing cardiac catheterization. Continuous wave Doppler ultrasound was employed to estimate the mean transvalvular pressure gradient. The mean left ventricular outflow tract flow velocity and cross-sectional area were determined from pulsed Doppler and two-dimensional ultrasound recordings. ⋯ Bioimpedance cardiac output measurements agreed with the average of Fick and indicator dye estimates (r = +0.90, SEE = 0.52). Valve area estimates utilizing continuous wave Doppler ultrasound and electrical bioimpedance were superior (r = +0.91, SEE = 0.12) to estimates obtained utilizing the continuity equation (r = +0.76, SEE = 0.29) and were more reliable in the detection of patients with severe aortic stenosis (9 of 11 versus 6 of 11). These data show that 1) electrical bioimpedance methods accurately estimate cardiac output in the presence of aortic stenosis; 2) the hybridized bioimpedance-Doppler ultrasound method yields accurate estimates of aortic stenosis area; and 3) the speed, accuracy and cost-effectiveness of aortic stenosis evaluation may be improved by this hybridized approach.
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J. Am. Coll. Cardiol. · Jan 1988
Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure.
The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. ⋯ The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.