The Mechanisms and Importance of Tricuspid Regurgitation and Hepatic Pulsations in Dilated Cardiomyopathy: A Review

Secondary tricuspid regurgitation is a common finding in dilated cardiomyopathy, being present in up to 90% of patients studied with Doppler echocardiography. It appears to be primarily due to annular dilatation and loss of the sphincter-like action of the tricuspid annulus during systole. Apical displacement of the papillary muscle and increased chordal tension may also contribute to mal-coaptation of the tricuspid leaflets in systole. Hepatic pulsations generally occur late in dilated cardiomyopathy, indicating hepatic congestion due to progressive biventricular failure. These are thought to result from secondary tricuspid regurgitation and transmission of the regurgitant v wave to the liver. Careful pulsed-Doppler studies of the timing of hepatic pulsations in dilated cardiomyopathy often show them to be presystolic, rather than systolic, suggesting that a mechanism other than tricuspid regurgitation may be responsible. (ECHOCARDIOGRAPHY, Volume 8, March 1991)     

Circadian Variations of Heart Rate and STIMT Interval: Adaptation for Nighttime Pacing

In order to determine the optimal pacing rate for pacemaker patients at night, 150 normal subjects with regular sinus rhythm and free of manifest heart disease, were studied using 24-hour Holter monitoring. Minimum and average heart rates were analyzed on an hourly basis. The study group was divided into six age groups, 25 subjects each, ranging from 20-29 years to 60-69 years. The minimum heart rate during the night was found to be lower than 65 ppm for all groups. The youngest subjects showed the largest variation in the minimum heart rate. The results suggest that an automatic lowering of the pacing rate during the night would allow for longer periods of sinus rhythm, thereby improving hemodynamic performance and reducing pacemaker power consumption. Suitable sensors for automatic lowering of the pacing rate include inbuilt 24-hour clock systems and the QT interval that lengthens during sleep.     

Assessment of Long-Term Stability of Chronic Ventricular Pacing Thresholds in Steroid-Eluting Electrodes

Sixteen patients with Medtronic 4003 steroid-eluting electrodes implanted in the ventricular position were followed over 5 years. In each patient a special type of Medtronic 2443 pacemaker was implanted to allow programming of output at 1.35 V. Chronic threshold values in these patients measured at an output of 1,35 V were stable over the first 18 months of follow-up. Mean values were: 0.06 ± 0.03 msec at 6 months and 0.08 ± 0.02 msec at 18 months; these did not differ from each other significantly. However, during the period from 18 to 36 months postimplantation, a significant increase in mean pacing threshold was observed: 0.08 ± 0.02 msec at 18 months postimplantation versus 0.14 ± 0.05 msec at 36 months (P < 0.01), After 36 months, the chronic pacing threshold remained stable until the end of the 5-year follow-up period. Further long-term study of chronic threshold behavior of steroid-eluting electrodes measured at low amplitudes is warranted.     

β-ENDORPHIN: SYNTHESIS AND RADIORECEPTOR BINDING ACTIVITY OF βh-ENDORPHIN-(1–27) AND ITS ANALOGS

β_h-Endorphin-(1–27) (I), [Ac-Tyr¹]-β_h-endorphin-(1–27) (II), [Gln⁸]-β_h-endor-phin-(1–27) (III), and [Ac-Tyr¹, Gln⁸]-β_h-endorphin-(1–27) (IV) were synthe sized by the solid-phase method. The binding potency of I-IV to rat brain membrane preparations was measured by radioreceptor binding assay. The relative potencies were: β_h-endorphin, 100; I, 30; II, 0.04; III, 90; IV, 0.07.     

A comparison of vincristine and doxorubicin infusional chemotherapy with methylprednisolone (VAMP) with the addition of weekly cyclophosphamide (C-VAMP) as induction treatment followed by autografting in previously untreated myeloma

In a sequential nonrandomized study, 204 consecutive unselected patients aged < 70 years received induction chemotherapy with infusional vincristine and adriamycin with oral methyl prednisolone (VAMP; n =75) or with additional cyclophosphamide, C-VAMP ( n =129). 38/129 C-VAMP patients also received verapamil during induction as part of a controlled trial with the aim to overcome drug resistance. A median of five courses (range 1–11) of chemotherapy were required before maximal response was attained and this was similar in both groups. An over-all response rate of 71% was noted at the end of induction. The complete remission (CR) rate with C-VAMP was 24%, which was significantly higher ( P =0.04) than the CR rate with VAMP alone (8%). The addition of verapamil did not alter the response rate of C-VAMP. Compliance to VAMP was overall 83% and not affected by the addition of cyclophosphamide. The proportion of patients going on to receive high-dose chemotherapy and an autograft was the same for VAMP and C-VAMP treated patients (71%). The median overall survival (OS) and progression-free survival (PFS) for the whole group were 4.4 years and 2.0 years and no difference in outcome was observed between the different treatment groups. Therefore the addition of weekly cyclophosphamide to VAMP induction therapy has significantly improved the response rates of previously untreated myeloma patients. C-VAMP was not more toxic and did not compromise the chances of receiving an autograft. Verapamil was without influence on any parameters in this study.