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)