Long-term Reproducibility of Response to Noninvasive Programmed Cardiac Stimulation in Spontaneous, Sustained Ventricular Tachycardia Treated with Amiodarone Therapy

A total of 73 noninvasive serial electrophysiological studies were carried out in 12 patients with spontaneous sustained ventricular tachycardia, inducible in spite of chronic treatment with amiodarone, in order to verify the effect of this drug on the long-term reproducibility of the test. A ventricular tachycardia was induced in 72 of 73 times; in 59% of cases, the clinical form was induced. In 8 of 12 patients, two or more types or morphologies of ventricular tachycardia could be induced. The induction modes (driving rate and number of extrastimuli) changed considerably in different studies. During a follow-up of 12 ± 6 months, 5 out of 12 patients had spontaneous relapses. We observed no differences between these patients and the others regarding inducibility, types and morphologies of the induced tachycardias, or induction modes. Therefore, when ventricular tachycardia is inducible in spite of chronic amiodarone therapy, it is always inducible during follow-up, even if a great intrapatient change of type and the morphology of induced tachycardias and induction modes is observed. However, since similar electrophysiological features are present in patients with and without spontaneous recurrence of ventricular tachycardia, serial electrophysiological studies are of little value in predicting the clinical outcome.     

Complete Epicardial Resynchronization Device Implantation in a Patient Who Underwent a Replacement of Mitral and Tricuspid Valve

A 71‐year‐old woman with severe nonischemic dilated cardiomyopathy and low ejection fraction with severe mitral regurgitation and tricuspid regurgitation and pulmonary hypertension underwent multiple valve repairs and cardiac resynchronization therapy implantation with epicardial shock leads. (PACE 2013; 36:e56–e58)     

Ventricular Cross Stimulation in a Dual Chamber Pacing System: Phenomenon Analysis

Seven cases of ventricular cross stimulation from a group of 23 patients implanted with DDD devices are presented. In two patients the phenomenon was observed at the moment of DDD programming at nominal values, and in five other patients it was reproduced by increasing the atrial output voltage up to ten volts. In all 23 patients cross stimulation disappeared permanently within 24 hours after implantation. From the onset of cross stimulation to its end, atrial and ventricular threshold voltages were unchanged, while the atrial and ventricular impedances significantly decreased. These results suggest that an important role in the phenomenon occurs by impedance variation at the interface between the pulse generator and body tissue.     

Opioid pathways exert a tonic restraint in the guinea-pig isolated colon: changes after chronic sympathetic denervation

Abstract— We have studied the effects of naloxone on acetylcholine and noradrenaline release in the guinea-pig isolated distal colon, and have assessed the effect of naloxone on electrically-induced contractions of the longitudinal muscle and non-adrenergic, non-cholinergic (NANC) relaxations of the circular muscle coat. Naloxone dose-dependently increased resting and electrically-evoked acetylcholine release and electrically-evoked noradrenaline release. Naloxone was more potent in increasing resting acetylcholine release in colonic specimens obtained after chronic sympathetic denervation. Naloxone (1 μm ) did not affect electrically-induced contractions of the longitudinal muscle, while it enhanced NANC relaxations of the circular muscle. The effects observed with naloxone in the present experiments suggest that opioid pathways exert a tonic restraint on neurotransmission in the guinea-pig colon. After suppression of the adrenergic inhibitory tone, the functional relevance of opioid pathways seems to be increased.     

Modulation of all-trans retinoid acid pharmacokinetics in acute promyelocytic leukaemia by prolonged interferon-α therapy

Summary. Continuous treatment with all-trans retinoid acid (ATRA) induces accelerated drag catabolism which is considered responsible for acquired resistance to ATRA. We studied the effect of interferon-o:2a (IFN) on ATRA pharmacokinetics in two patients with acute promyelocytic leukaemia (APL) in complete remission maintained by alternating 15d of IFN and 15 d of ATRA. Day 15 ATRA levels obtained during IFN + ATRA treatment were significantly higher than those observed in patients maintained on ATRA alone. In one patient IFN was discontinued and day 15 ATRA levels decreased to those observed in patients scheduled for maintenance with ATRA alone. In our two patients IFN substantially reduced the induction of ATRA catabolism, indicating a potential role for IFN in modulating ATRA pharmacokinetics.     

Conformation of linear homo-oligoprolines

A conformational analysis of Piv-l-Pro-d-Pro-OMe was performed in the solid state using i.r. absorption and X-ray diffraction. The tertiary amide bond is in the trans conformation, whereas the tertiary peptide bond is in the cis conformation. The sequence of the, ø angles is F, F*. The preferred conformations of the pivaloylamino group, the pyrrolidine rings, and the ester moiety are also discussed.     

Computed Tomography During Experimental Balloon Dilatation For Calcific Aortic Stenosis. A Look into the Mechanism of Valvuloplasty

Thin-slice contiguous computed tomographic scanning was performed in four postmortem hearts with calcific aortic valve stenosis (mean weight: 583 ± 78 g; mean age: 65 ± 10 years) before, during, and after balloon valvuloplasty. Balloons of increasing diameter (15–19 mm single balloons, and 3 × 12-mm trefoil-shaped balloon) were positioned across the aortic valve and manually inflated to pressures of 3 to 4 atmospheres. During inflation of the 3 × 12-mm balloon a larger residual orifice, potentially free for blood passage, was observed in the two cases with bicuspid valves and in one case with a fused tricuspid valve, while the reverse was noted in one case with a tricuspid valve without fusion. In most cases valvular orifice enlargement only occurred with larger diameter balloons. After valvuloplasty aortic valve area increased from 0.72 (range 0.20–0.95) cm² to 2.36 (range 0.95–3.14) cm². The smallest orifice enlargement after dilatation occurred in case 1, where valvular calcified deposits had the largest volume and the highest computed tomographic attenuation value. In each patient macroscopic changes (fracture of nodular calcifications, commissural splitting, tearing of the central raphe) were noted. No calcium dislodgement or aortic ring damage was observed. In autopsy specimens computed tomography provided accurate evaluation of aortic valve morphology, extent of valve calcification, balloon-leaflet relationship during inflation, and effects of the dilatation on valve leaflets and commissures. Advances in computed tomographic cardiovascular imaging may achieve similar results in the clinical setting, and allow a more rational, individualized approach to the valvuloplasty procedure. (J Interven Cardiol 1988:1:2)     

PREPARATION AND CONFORMATIONAL STUDY OF CLUPEINE FRAGMENTS*

Fragments of clupeines YI, YII, and Z of divergent chain length and different amino acid composition were prepared by digestion with thermolysin and a mixture of carboxypeptidases A and B, and their conformational preferences examined as a function of pH, added salts, presence of a helix-supporting solvent, and temperature. All these highly basic oligopeptides adopt an essentially unordered conformation in aqueous solution. 2-Chloroethanol supports in various amounts the onset of the right-handed α-helical form in the carboxypeptidase fragments.