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H Stoeckle

Publications and source records attributed to H Stoeckle.

At least 19 recordsLinked to original sources
PubMed1999

Double pulse transthoracic defibrillation in the calf using percent fibrillation cycle length as spacing determinate.

Recent studies have found that when multiple pulses of energy are used for defibrillation with implantable electrodes, the spacing between these pulses is better determined as a percentage of the fibrillation cycle length (CL), rather than as a fixed function of time. Here, this concept is further tested in the transthoracic defibrillation of calves, which are approximately the size of heavy humans. Eleven 90-110 kg calves (101 +/- 6 kg) were used in evaluating the effectiveness in achieving transthoracic ventricular defibrillation of ten double pulse waveforms (two 50 A 4-ms rectangular monopulses) having leading edge-to-edge spacings of 4 ms (a 50 A 8-ms rectangular monopulse) and 50, 60, 70, 80, 90, 100, 110, 120, 130 percent fibrillation CL, respectively. In each of these waveforms, the total time when 50 A current was flowing (on time) was 8 ms. Our results show an unequivocal adverse interaction between the pulses, when the spacing is around 60%-70% fibrillation CL; but that the two pulses combined to defibrillate as effectively as a single 8-ms pulse when the spacing is around 110%-130% fibrillation CL. Electrocardiographic analysis suggests that the adverse interaction is due to a refibrillation phenomenon. This study confirms that double pulses can interact and have a negative effect on defibrillation efficacy. Our data suggests that the mechanism of this interaction involves the second pulse reinitiating fibrillation when the pulse separation is in a critical range of values. Our results are also compatible with the hypothesis that the spacing of multiple pulses is better determined as a percentage of the fibrillation CL than as absolute time, although more study is necessary to fully test this hypothesis.

Animals↗
PubMed1989

Superiority of biphasic shocks in the defibrillation of dogs by epicardial patches and catheter electrodes.

Currently available internal cardiac defibrillators use a uniphasic, truncated exponential waveform morphology of about 6 msec in duration at an energy level of 23 to 33 joules. To determine if improved defibrillation could be achieved with a different waveform morphology, we implanted 4.5 cm2 titanium patches to the left and right ventricle of 28 dogs. After ventricular fibrillation was induced, defibrillation was attempted using 7, 12, 13, or 17 joules. A 5 msec rectangular uniphasic waveform morphology was compared with a 10 msec rectangular biphasic waveform with the lagging 5 msec pulse of half the amplitude of the leading 5 msec. In an additional seven dogs, a transvenous bipolar catheter was placed with the distal electrode in the right ventricular apex and the proximal electrode in the superior vena cava. Biphasic and uniphasic shocks were compared at 14 joules. In the patch-patch system, the biphasic waveform was superior to the uniphasic waveform at 7 joules (67% versus 35%, p less than 0.001) and at 12 joules (93% versus 78%, p less than 0.001). No statistically significant differences were achieved at 13 joules or 17 joules. In the catheter electrode system with a delivered energy of 14 joules, the biphasic waveform was more effective than the uniphasic waveform (87% versus 27%, p less than 0.001). Manufacturers of automatic implantable defibrillators should consider this information in the design of future automatic implantable defibrillators.

Animals↗
PubMed1987

Transluminal balloon dilatation for discrete subaortic stenosis.

Ten children, 10 weeks to 18 years old, with discrete subaortic stenosis (DSS) underwent transluminal balloon dilatation of the subaortic obstruction. The DSS was visualized by 2-dimensional echocardiography and cineangiography. Six patients had a thin discrete "membrane" immediately below the aortic valve (group I) and 4 patients had a thicker fibromuscular ring about 1 cm below the aortic valve (group II). In group I, the mean gradient decreased from 82 +/- 49 mm Hg (range 35 to 164) to 22 +/- 15 mm Hg (range 5 to 40); in group II, it decreased from 155 +/- 18 mm Hg (range 132 to 177) to 85 +/- 44 mm Hg (range 60 to 150). Three patients had follow-up cardiac catheterization 1 year later. Their mean gradient soon after the procedure was 37 +/- 23 mm Hg. On follow-up, it was still 37 +/- 19 mm Hg, indicating persistence of relief of the obstruction. Because of the high residual gradient in group II, 3 patients had surgical relief of the obstruction. The degree of aortic regurgitation present before the dilatation in all 10 patients did not change after the procedure. The mechanism of relief of the obstruction was by tearing of the subaortic membrane. Our data suggest that relief of subaortic obstruction is more favorable in the thin, membranous DSS.

Adolescent↗
PubMed1987

Is the effectiveness of cardiac ventricular defibrillation dependent upon polarity?

Studies involving 240 fibrillation-defibrillation episodes via epicardial patch electrodes in 21-27-kg dogs and 480 transthoracic episodes in 100-kg calves are reported. In dogs, 120 episodes involving shocks by a 3.7-A, 5-ms unidirectional rectangular wave of one polarity were interlaced with 120 similar episodes of the reverse polarity. When the upper right ventricular patch was positive with respect to the left ventricular apex patch, 85% of the episodes yielded defibrillation; 78% defibrillated with the reverse polarity. In one series in calves, 120 episodes involving shocks by a 42-A, 4-ms unidirectional rectangular wave of one polarity were interlaced with 120 similar episodes involving the reverse polarity. In a second series, 59-A, 4-ms shocks were employed. In the 42-A series, 38% of the episodes were successful when the upper right electrode was positive with respect to the electrode over the apex, and 28% were successful with the reverse polarity. Corresponding results in the 59-A series were 80% and 68%, respectively. On an unpaired basis, the three p values were 0.19, 0.14, and 0.04, respectively. On a paired basis, all three comparisons yielded significant differences (p less than 0.05). We conclude that in these cases, at least, there is a moderate dependence upon electrode polarity and that our results appear to warrant clinical studies.

Animals↗
PubMed1984

Transluminal balloon coarctation angioplasty: experience with 27 patients.

Transluminal balloon angioplasty (BA) was performed in 27 consecutive patients with coarctation of the aorta (COA), including 7 infants with preductal COA, 7 patients with restenosed COA after surgical repair, and 13 older children and 1 adult with unoperated COA. The patients were 4 days to 27 years old. The balloon was positioned across the COA and inflated sequentially to pressures of 100 and 120 psi, each inflation lasting for 5 to 10 seconds. Peak systolic pressure gradient (PSG) across the COA was recorded and an aortogram was performed before and immediately after BA. PSG also was recorded during follow-up studies performed in 13 patients 3 to 24 months after BA. BA was performed without complications in each patient. Immediately after BA, the mean PSG was reduced from 49 +/- 21 to 10 +/- 7 mm Hg (p less than 0.01), and the mean COA diameter increased from 3.9 +/- 1.4 to 9.6 +/- 3.6 mm (p less than 0.01). After a follow-up period of 3 to 24 months, the mean PSG remained low (15 +/- 11 mm Hg) and the mean COA diameter increased to 10.5 +/- 4.6 mm. BA can be performed safely. It can be a useful palliative treatment in seriously ill infants with COA.

Adolescent↗
PubMed1984

Defibrillation of 100 kg calves with asymmetrical, bidirectional, rectangular pulses.

The effectiveness in reversing ventricular fibrillation of 30 s duration of asymmetrical, bidirectional, rectangular waveforms in which the lagging half-cycle has the same duration but lower amplitude than the leading portion of the waveform was evaluated in a 2160-episode study involving anaesthetised calves. An additional 480-episode auxiliary study involved the interlacing of unidirectional and bidirectional wave episodes. The leading half-cycles of the 18 bidirectional waveforms evaluated were 35 A at 8 and 16 ms, 50 A at 4 and 8 ms, and 70 A at 2 and 4 ms. Associated with each of the six leading half-cycle configurations were lagging half-cycles having reverse current levels of 1/8th, 1/4th, and 1/2 of the leading half-cycle current amplitudes. Six waveforms were successful in 97% or more of the transthoracic episodes. Of these, three were 100% successful. Our data, when combined with those from earlier unidirectional and symmetrical, bidirectional, rectangular waveform studies, suggest that a broad category of bidirectional rectangular shocks are superior to the most favourable unidirectional rectangular shock.

Animals↗
PubMed1982

Transthoracic defibrillation in 100-kg calves with sequentially applied pulses.

The effectiveness of up to five 50-A, 4-ms rectangular pulses (each nominally 50% successful) followed, when required, by up to six 70-A, 6-ms pulses applied at 15-s intervals in reversing ventricular fibrillation in 100-kg calves was studied in 600 episodes in which 50-A, 6-ms; 70-A, 3-ms; 70-A, 6-ms; 70-A, 12-ms; or 100-A, 6-ms prefibrillation shocks had been delivered 5 s before the induction of fibrillation and in another 600 episodes in which the prefibrillation shock was omitted. We found that 1) there was a modest adverse influence of the prefibrillation shock upon the outcome of the 50-A, 4-ms portion of the sequential shock effort; 2) The 50-A, 4-ms shocks remained reasonably successful throughout the five-shock sequence; 3) when the prefibrillation shock was omitted, the time intervals for a return of a ventricular complex and normal sinus rhythm in the postdefibrillation electrocardiogram increased rapidly with the number of shocks required for defibrillation; and 4) if defibrillation was not achieved with the five-shock sequence, a single 70-A, 6-ms shock was about 94% successful and the sequence of up to six shocks was 100% successful.

Animals↗
PubMed1979

Scaling current and energy with body weight: requirements for the transthoracic ventricular defibrillation of calves as they grow from 50 to 150 kg.

To test the hypothesis that the effectiveness of a shock in achieving ventricular defibrillation is relatively independent of body weight if electrode diameter is proportional to the one-third power and current is proportional to the two-thirds power of weight, we studied defibrillation rates in 10 calves as they increased weight. At 50 kg, each calf was subjected to 20 fibrillation-defibrillation episodes using 10.3-cm diameter electrodes and 32-amp, 4-msec rectangular pulses for defibrillation. Two days after the original study, each calf underwent 20 additional episodes involving 44-amp pulses. With the specified scaling of electrode diameter and pulse amplitude, the two studies were repeated at weight intervals of 25 kg as the animals grew. Six calves survived. In the study that started with 32-amp pulses, first-shock success values of 28%, 49%, 66%, 51% and 23% were found in the six surviving calves at 50, 75, 100, 125 and 150 kg, respectively. The corresponding values were 93%, 96%, 93%, 94% and 91% in the study that started with 44-amp pulses. While the results of the 32-amp study fail to support our initial hypothesis, those obtained in the 44-amp current study appear compatible with the hypothesis.

Animals↗
PubMed1977

Transthoracic ventricular defibrillation in the 100 kg calf with unidirectional rectangular pulses.

The effectiveness in reversing ventricular fibrillation of 30 seconds duration of unidirectional rectangular-wave shocks having pulse widths of 0.5 through 64 msec, pulse amplitudes of 35, 50, 70, 100, and 140 amp, and pulse energies of 109 through 1,660 J was studied in 3,303 transthoracic fibrillation-defibrillation episodes in 100 kg calves. A total of 38 animals were used in the study. Postdefibrillation electrocardiograms were recorded. Families of curves of percent successful defibrillation vs pulse duration, percent successful defibrillation vs pulse energy, duration of postdefibrillation complete block or standstill vs energy, and time required for a return to normal sinus rhythm vs energy were derived. The most effective waveform studied (70 amp--8 msec--862 J) yielded defibrillation on the initial attempt in 93% of 120 episodes. In general, the duration of complete block or standstill and the time required for a return to normal sinus rhythm increased with increasing pulse current and pulse energy.

Animals↗
PubMed1975

XO/XY mosaicism in a 2 year phenotypic male.

A 2-year-old male with bilateral undescended gonads, hypoplastic external auditory canals, large umbilical hernia and XO/XY chromosome mosaicism is described in this communication. Salient features of other similar cases, i.e. XO/XY mosaicism in phenotypic males, from the literature are summarized, showing the wide diversity of manifestations of this syndrome.

Disorders of Sex Development↗