Evaluation of a pharmacist-led penicillin allergy de-labelling ward round: a novel antimicrobial stewardship intervention

BACKGROUND

Antibiotic allergy labels (AALs), reported by up to 25% of hospitalized patients, are a significant barrier to appropriate prescribing and a focus of antimicrobial stewardship (AMS) programmes.

METHODS

A prospective audit of a pharmacist-led AMS penicillin allergy de-labelling ward round at Austin Health (Melbourne, Australia) was evaluated. Eligible inpatients with a documented penicillin allergy receiving an antibiotic were identified via an electronic medical report and then reviewed by a pharmacist-led AMS team. The audit outcomes evaluated were: (i) AMS post-prescription review recommendations; (ii) direct de-labelling; (iii) inpatient oral rechallenge referral; (iv) skin prick testing/intradermal testing referral; and (v) outpatient antibiotic allergy clinic assessment.

RESULTS

Across a 5 month period, 106 patients were identified from a real-time electronic prescribing antibiotic allergy report. The highest rate of penicillin allergy de-labelling was demonstrated in patients who were referred for an inpatient oral rechallenge with 95.2% (n = 21) successfully having their penicillin AAL removed. From the 22 patients with Type A reactions, 63.6% had their penicillin AAL removed. We demonstrated a significant decrease in the prescribing of restricted antibiotics (defined as third- or fourth-generation cephalosporins, fluoroquinolones, glycopeptides, carbapenems, piperacillin/tazobactam, lincosamides, linezolid or daptomycin) in patients reviewed (pre 42.5% versus post 17.9%, P = 0.0002).

CONCLUSIONS

A pharmacist-led AMS penicillin allergy de-labelling ward round reduced penicillin AALs and the prescribing of restricted antibiotics. This model could be implemented at other hospitals with existing AMS programmes.

P2842Sequential application of horizontal and vertical orientation on radiofrequency ablation lesions produced by thermocool smarttouch SF catheter

Background

Ablation lesions represent a complex interaction between the ablation catheter configuration and tissue anatomy. An understanding of each variable can assist in determination of the optimal lesion set. One such variable is the catheter orientation. With an irrigated radiofrequency ablation catheter with 6 pores (6P) near the distal tip, lesion surface area and volumes are smaller in the horizontal catheter orientation compared to the vertical catheter orientation. This finding is explained by the 6P irrigation catheter design, where irrigation fluid is discharged from six ports around the circumference of the electrode. Introduced in 2015, the ThermoCool SmartTouch® SF catheter has a 56-pore (56P) distribution to provide high density low volume irrigation settings. Irrigation catheters create smaller lesions in horizontal orientation compared to vertical orientation, however this has not been studied for the 56P irrigated catheter.

Purpose

Evaluate the impact of catheter orientation with sequential application of 56P catheter.

Methods

Ablation lesions were created on additive-free chicken model in a saline bath heated to 37°C using the 56P catheter under standard flow rate (8cc/min) conditions. Ablation energy of 20W and 30W was delivered twice for 30 seconds with 3 minutes interval between applications. Contact force (CF) of 5, 10, 15, and 20g was applied with the following conditions: horizontal catheter orientation followed by horizontal (HH), vertical by vertical (VV), horizontal by vertical (HV), and vertical by horizontal catheter orientation (VH). Measurements were obtained by lesion dissection through the midpoint by 3 independent operators. Kruskal-Wallis test was used for comparison of lesion depth, surface area and volume.

Results

Ninety-six lesions were analyzed. No coagulum or steam pops were included in the analysis. The minimum and maximum lesion depth, surface area and volume were 1.5 & 6.0 mm, 14.1 & 117.7mm2, 47.1 & 471.0 mm3 respectively. There was no significant difference in the lesion depth, surface area or volume in HH, VV, HV or VH orientation at different CF with 20W and 30W. (Fig 1)

Figure 1

Conclusion

Unlike other irrigated catheters, catheter orientation with sequential application with different CF and power did not impact lesion depth, surface area and volume with 56P catheter. This finding could be considered useful in situations where the catheter orientation could be challenging owing to tissue anatomy to achieve adequate lesion size.

Acknowledgement/Funding

UVA Health System

Receptor homodimerization plays a critical role in a novel dominant negative P2RY12 variant identified in a family with severe bleeding

Essentials Three dominant variants for the autosomal recessive bleeding disorder type-8 have been described. To date, there has been no phenotype/genotype correlation explaining their dominant transmission. Proline plays an important role in P2Y12R ligand binding and signaling defects. P2Y12R homodimer formation is critical for the receptor function and signaling.

SUMMARY

Background Although inherited platelet disorders are still underdiagnosed worldwide, advances in molecular techniques are improving disease diagnosis and patient management. Objective To identify and characterize the mechanism underlying the bleeding phenotype in a Caucasian family with an autosomal dominant P2RY12 variant. Methods Full blood counts, platelet aggregometry, flow cytometry and western blotting were performed before next-generation sequencing (NGS). Detailed molecular analysis of the identified variant of the P2Y12 receptor (P2Y12R) was subsequently performed in mammalian cells overexpressing receptor constructs. Results All three referred individuals had markedly impaired ADP-induced platelet aggregation with primary wave only, despite normal total and surface P2Y12R expression. By NGS, a single P2RY12:c.G794C substitution (p.R265P) was identified in all affected individuals, and this was confirmed by Sanger sequencing. Mammalian cell experiments with the R265P-P2Y12R variant showed normal receptor surface expression versus wild-type (WT) P2Y12R. Agonist-stimulated R265P-P2Y12R function (both signaling and surface receptor loss) was reduced versus WT P2Y12R. Critically, R265P-P2Y12R acted in a dominant negative manner, with agonist-stimulated WT P2Y12R activity being reduced by variant coexpression, suggesting dramatic loss of WT homodimers. Importantly, platelet P2RY12 cDNA cloning and sequencing in two affected individuals also revealed three-fold mutant mRNA overexpression, decreasing even further the likelihood of WT homodimer formation. R265 located within extracellular loop 3 (EL3) is one of four residues that are important for receptor functional integrity, maintaining the binding pocket conformation and allowing rotation following ligand binding. Conclusion This novel dominant negative variant confirms the important role of R265 in EL3 in the functional integrity of P2Y12R, and suggests that pathologic heterodimer formation may underlie this family bleeding phenotype.

In vitro and in vivo anti-leukemia activity of CHR-2845, a cell-targeted HDAC inhibitor for use in monocytic leukemia

e14579

Background: Histone deacetylase inhibitors alter gene expression and induce apoptosis in a wide range of cancer cells including those derived from human leukemias. CHR-2845 is a novel hydroxamic acid derivative histone deacetylase inhibitor (HDACi) which is a selective substrate for the intracellular carboxylesterase hCE-1, whose expression is restricted to cells of the monocyte- macrophage lineage. Methods: We studied the in vitro and in vivo anti-leukemia activity of CHR-2845 using cell proliferation assay, annexin V binding assay, cell cycle analysis, western blot and in vitro primary leukemia cell culture. Results: Both U937 and THP1 cells express high levels of hCE-1 whereas the myeloid cell line, HL60, does not. In comparison to vorinostat, CHR-2845 showed increased anti-proliferative potency (IC50) against monocytic cell lines (THP1, 30 nM vs 700 nM and U937, 30 nM vs 475 nM), compared to a myeloid cell line (HL60, 700nM vs 470 nM). In a broad panel of leukemic cell lines, the potency of CHR-2845 over vorinostat correlated completely with hCE-1 expression. In monocytic cell lines, CHR-2845 induced more apoptosis than vorinostat (THP1: 45±5% vs 11±1% and U937: 23±14% vs 6±1%), as measured by flow cytometry using Annexin V. Biochemical assessment of histone H3 and H4 protein acetylation by Western blot also indicateed that CHR-2845 is at least 10 times more potent than vorinostat in monocytic cell lines but not in HL-60 cells. This increase in histone acetylation was associated with increased phosphohistone H2AX, indicating formation of double-strand DNA breaks induced by this compound. These data for CHR-2845 and vorinostat on apoptosis and histone acetylation in THP1 and U937 versus HL60 cells, confirmed the selectivity of this novel compound for cells of the monocytic lineage. We also studied the anti-leukemia activity of CHR-2845 in primary leukemia cells from 8 patients with acute or chronic myelomonocytic leukemia. CHR-2845 decreased proliferation and induced apoptosis more than an equivalent dose of vorinostat in some of the patients we studied. Conclusions: These results indicated that CHR-2845 has potential to be efficacious in the treatment of patients with monocytic leukemia.

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Experimental discordant hepatic xenotransplantation in the recipient with liver failure: implications for clinical bridging trials

BACKGROUND

Clinical xenotransplantation might start with bridge-to-bridge trials. Situations where hyperacute rejection is avoided would provide opportunities for the initiation of bridging trials. Patients with liver failure have a diminished capacity to initiate antibody and complement-induced injury of xenogeneic endothelium. Hyperacute rejection of a liver xenograft manifests as a coagulopathy. We examined the ability of a recipient with liver failure to hyperacutely reject a liver xenograft in the dog-to-pig model in the immediate postoperative period.

STUDY DESIGN

Liver failure in pigs was induced with galactosamine. Canine livers were transplanted into pigs with liver failure and into healthy pigs. The postoperative course was monitored for 1 hour for histologic changes in the xenograft, changes in platelet counts, and whole blood clotting with Sonoclot analysis. In vitro assays with pig serum and canine hepatic sinusoidal endothelial cells were used to assess the effect of liver failure on serum cytotoxicity and xenoreactive antibody levels.

RESULTS

All untreated pig recipients of liver xenografts died from a coagulopathy. Recipients with liver failure manifested no signs of coagulopathy, and had minimal change in platelet counts or Sonoclot (Sienco Inc., Morrison, CO) tracings. Liver xenograft biopsies from recipients with liver failure showed no evidence of the tissue injury that characterized the biopsies of control recipients. Serum from pigs was less cytotoxic to the canine hepatic sinusoidal endothelium after induction of liver failure. The xenoreactive antibody levels and repertoire were similar in the pig serum before and after liver failure was induced. CH50 (total complement) levels were diminished in pigs after the induction of liver failure.

CONCLUSIONS

Liver xenotransplantation used in bridging trials in recipients with liver failure might not face the barrier of hyperacute rejection.

Catheter ablation of ventricular tachycardia in patients with structural heart disease using cooled radiofrequency energy: results of a prospective multicenter study. Cooled RF Multi Center Investigators Group

OBJECTIVES

The purpose of this multicenter study was to evaluate the safety and efficacy of a radiofrequency (RF) catheter ablation system with internal saline irrigation.

BACKGROUND

Catheter ablation of ventricular tachycardia (VT) associated with structural heart disease is more difficult than ablation of idiopathic VT. The larger size of responsible reentrant circuits contributes to the difficulty in achieving an adequate ablation lesion with conventional techniques. Recently, cooling of the ablation electrode by saline irrigation has been shown to increase RF lesion size.

METHODS

The patient population included 146 patients who participated in the Cooled RF Ablation System clinical trial and underwent an attempt at ablation of VT occurring in the presence of structural heart disease. The duration of follow-up was 243 +/- 153 days.

RESULTS

Catheter ablation was acutely successful, as defined by elimination of all mappable VTs, in 106 patients (75%). In 59 patients (41%), no VT of any type was inducible after ablation. Twelve patients (8%) experienced a major complication. After catheter ablation, 66 patients (46%) developed one or more episodes of a sustained ventricular arrhythmia.

CONCLUSIONS

The results of this study demonstrate that catheter ablation of all mappable forms of sustained VT can be performed with high initial success and a moderate incidence of major complications (8%).

Social support, relationship quality, and well-being among pregnant adolescents

This study examined the role of social support and relationship quality on the well-being of pregnant adolescents. Sixty-seven Black and 43 White single pregnant teens participated in the study. The reciprocal exchange of support between parents and teens was correlated with increased mastery and life satisfaction and decreased depression and anxiety. However, the reciprocal exchange of support with friends did not correlate with well-being. A high quality relationship with a significant other was associated with increased self-esteem among pregnant teens dating the father of their child. This study extends the adolescent pregnancy literature by considering the reciprocal exchange of support and relationship quality with the partner.

Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy. Although these findings may be affected by imprecision of the data, the study suggests that manipulation of the timing of insemination during the cycle cannot be used to affect the sex of offspring.

School importance and dropout among pregnant adolescents

PURPOSE

This study examined the relationship of psychological well-being, social support, and demographic variables to school importance and school dropout among pregnant teens.

METHOD

Fifty-one Caucasians and 68 African-Americans (mean age = 16.7 years, mean weeks pregnant = 23) were recruited from two Baltimore area prenatal teen clinics. The adolescents completed questionnaires measuring depression, self-esteem, mastery, parental and friend support, demographic characteristics (i.e., age, marital status, ethnicity, socioeconomic status), school importance, and status.

RESULTS

Most adolescents were enrolled in school or had graduated (69.7%), were receiving at least passing grades (78.7%), and perceived finishing high school as very important (76.7%). Blacks were more likely to say school was important (p < 0.001), were less likely to drop out (p < 0.01), and received higher grades (p < 0.01) than whites. Dropouts had lower family incomes than current school attenders and graduates (p < 0.05). One measure of psychological well-being (mastery, p < 0.01) was positively correlated with school importance. Social support did not correlate with school importance or dropout.

CONCLUSIONS

These findings suggest that dropping out of school among pregnant teens may be more strongly related to sociocultural factors than to individual characteristics such as emotional support and psychological well-being. Overall, this study reveals a positive picture of educational continuation and performance during pregnancy, with most adolescents recognizing the importance of education and remaining in school.

Pregnancy complications in natural family planning users

A multicenter cohort study was designed to assess pregnancy outcome among natural family planning (NFP) users, and provide the opportunity to address complications in NFP users by planning status and by timing of conception with respect to day of ovulation. There were 877 singleton births in this sample. Complications evaluated were abnormal vaginal bleeding, urinary tract infection, vaginal infection, hypertension of pregnancy, proteinuria, glycosuria, and anemia. There was no significant difference in the mean age, number of prenatal visits or birth weight among optimally and non-optimally timed pregnancies or for planned and unplanned pregnancies. There were higher incidences of "parity 2 or more" and current smokers in the non-optimally timed pregnancies and lower incidences of prior pregnancy loss and "currently employed" in the non-optimally timed pregnancies. There was little difference in pregnancy complications with respect to pregnancy timing, with the exception of a significant increased risk of vaginal bleeding late in pregnancy among non-optimally timed conceptions (11.5%) compared to optimally timed pregnancies (5.2%, RR = 2.2, 95% CI 1.3-3.7). More differences were observed in pregnancy complication rates by planning status. Unplanned pregnancies were associated with significantly more late pregnancy bleeding, vaginal infections, proteinuria, glycosuria and medication use than planned pregnancies. Unplanned pregnancies had lower incidences of maternal anemia. Complications of pregnancy were low in this NFP population, irrespective of planned versus unplanned status. Women with planned pregnancies had even fewer complications during pregnancy than women with unplanned conceptions, suggesting that women using NFP to plan their reproduction may be at particularly low risk.

Effects of timing of conception on birth weight and preterm delivery of natural family planning users

OBJECTIVE

Various birth defects and untoward perinatal outcomes have been claimed to be associated with pregnancies conceived by gametes aged in vivo before fertilization. Thus, these outcomes were systematically assessed in pregnancies occurring in natural family planning (NFP) users. Our international multicenter cohort study of NFP pregnancies (n = 877) is by far the largest systematic study designed to assess pregnancy outcome and is of sufficient power to allow us to address the concern of low birth weight (< 2500 g) and preterm delivery (< 37 weeks gestation).

STUDY DESIGN

In addition to gathering baseline medical data, evaluation was performed at 16 weeks, 32 weeks and at term. Data were collected in a systematic cohort fashion, verified by the five collaborating international recruiting centers, and analyzed by investigators in the US. Most recruiting center principal investigators are obstetrician-gynecologists and, if not, have integral relationships with such specialists. Standard criteria could thus be applied within and among centers. In our cohort, birth weight was recorded accurately at delivery. Almost all of the deliveries occurred in hospitals; thus, data should be quite reliable. Neonatal examination for anomalies was usually conducted immediately after delivery, when birth weight was recorded.

RESULTS

Analysis of risk factors for low birth weight and preterm delivery showed that this population had a low risk profile. Low birth weight infants (< 2500 g) and preterm deliveries were increased among women with a history of either prior low birth weight or preeclampsia in the index pregnancy. However, mean birth weight was unaffected by the timing of conception vis à vis ovulation or pregnancy history. Mean birth weight for the 877 singleton NFP pregnancies was 3349.6 g. The risk of preterm delivery was increased among older women who drank alcohol, but there were no significant effects of timing of conception vis à vis ovulation on preterm delivery. Results held when analysis was stratified according to whether NFP was being used for contraception or to achieve pregnancy.

CONCLUSIONS

Our data do not appear to show striking differences between 877 NFP pregnancies and the general obstetric population. The timing of conception vis à vis ovulation does not exert significant effects on the birth weight or preterm delivery of resulting pregnancies, a reassuring finding for NFP users.

Further evidence that infection is an infrequent cause of first trimester spontaneous abortion

A previous cohort study found no clinical evidence that infection occurred more often in subjects experiencing pregnancy loss compared with those experiencing successful pregnancy [Simpson et al. (1996) Hum. Reprod., 11, 668-672]. Given these surprising findings, we conducted a similar analysis on another cohort also followed prospectively. Using couples practising natural family planning for conception or contraception, information on clinical evidence of infection was gathered beginning with week 5 of gestation. Information on fever and signs of overt infection was specifically sought by interview and physical examination. Frequencies of urinary, vaginal and other infections in subjects experiencing pregnancy loss were 11.1, 9.5 and 8.7% respectively, not significantly different from rates in subjects having liveborns (10.1, 10.2 and 10.3% respectively). Thus, no association between clinical infection and early pregnancy loss (< or = 16 weeks) was observed. Cohort studies utilizing biologically based assays are awaited because extant data do not provide evidence that clinically evident infections play major roles in first trimester pregnancy losses.

Normocalcemic hyperparathyroidism associated with relatively low 1:25 vitamin D levels post-renal transplant can be successfully treated with oral calcitriol

Since endogenous 1:25 vitamin D (1:25VD) is principally involved with involution of secondary hyperparathyroidism post-renal transplant we correlated 1:25VD levels with intact PTH in 82 random patients with a serum creatinine of < 2 mg/dl and with normal hepatic function. All patients studied were normocalcemic with normal phosphorus and received azathioprine, cyclosporin A and prednisone. Of considerable interest, of the 42 patients studied after 2 years post-transplant, there were 8 (19%) patients with intact PTH of more than twice the upper limit of normal (normal 10-65 pg/ml) and other 15 (36%) with PTH levels above normal. Secondly, in no patient did we see 1:25VD above normal (normal 15-60 pg/ml) despite levels of PTH of > 200 pg/ml. Of concern, 20% of 73 patients had 1:25VD deficiency (< 15 pg/ml). This may not have been previously appreciated because of the number of patients studied. Like previous investigators, we failed to understand why 1:25VD levels were relatively low. There was no correlation between 1:25VD and serum creatinine. Of 25 patients with a serum creatinine of 1.4 or less, there were 10 patients (40%) with 1:25VD of less than 20 pg/ml. Since persistently high PTH can contribute to bone demineralization, which is not uncommon post-transplant, we treated 8 patients with small doses of oral 1:25VD (rocaltrol). In less than 6 months PTH levels returned to normal in 7 of the 8 patients. The current studies clearly indicate that asymptomatic hyperparathyroidism is common even after 2 years post-renal transplant. Monitoring for PTH and 1:25VD will help prevent bone disease post-transplant now that rocaltrol is available.

Efficacy of the symptothermal method of natural family planning in lactating women after the return of menses

This study was designed to determine the efficacy of the symptothermal method of natural family planning during lactation. Although the method appears to give a reasonable reflection of fertility potential over time, it overlaps with the profound influence of lactation in both ovulation suppression and the delay of luteal phase adequacy. Further analysis is planned to attempt to identify those particular mucus signs and symptoms that are helpful during the transition from lactational amenorrhea to normal cycling.

Splenic infarction complicating pediatric liver transplantation: incidence and CT appearance

In children it is often necessary to ligate the splenic artery and the main collateral supply to the spleen during liver transplantation. The complication of splenic infarction has been observed on postoperative CT in such patients. The purpose of our study was to determine the incidence and CT appearance of splenic infarction and to correlate its occurrence with a vascular cause related to the operative procedure. During a 2 year period, 26 of 94 (28%) children receiving liver transplants developed splenic infarction as shown by CT. Infarction generally occurred within 2 weeks of transplantation. Computed tomography demonstrated variable portions of splenic involvement with hypodense lesions. Twenty-two of 39 (56%) patients whose splenic artery was ligated developed splenic infarctions. Only 4 of 55 (7%) patients whose splenic artery was left intact had splenic infarctions on postoperative CT. We conclude that there is an increased incidence of splenic infarction in pediatric liver transplant recipients. The incidence of infarction is related to ligation of the splenic artery and collateral pathways.

Abdominal organ cluster transplantation for the treatment of upper abdominal malignancies

Ten patients with primary malignant tumors of the biliary tract, duodenum, or stomach and with secondary involvement of the liver underwent removal of most or all of the stomach, liver, pancreas, spleen, duodenum, proximal jejunum, terminal ileum, and ascending and transverse colon. The void in the upper abdomen was filled with an organ cluster graft consisting of the liver, pancreas, duodenum, and variable segments of proximal jejunum. Eight of the ten patients are alive after 3 to 9 months, all with good liver and pancreas function, and most with satisfactory function of the gastrointestinal tract. One of the surviving patients was in the hospital for 4 months because of multiple enteric fistulas and infections; the other seven survivors were discharged after an average of 43 +/- 17.61 (SD) days. Recurrent tumor has not been proved in any of the surviving recipients and is suspected in only one. The study of such cases should provide insight and guidelines applicable to other visceral transplantation procedures that may be attempted in the future.

Clinical and electrophysiologic effects of amiodarone in patients with atrial fibrillation complicating the Wolff-Parkinson-White syndrome

The clinical and electrophysiologic effects of oral amiodarone were evaluated in 10 patients with a history of spontaneous atrial fibrillation and a rapid ventricular response, complicating the Wolff-Parkinson-White syndrome. Five patients developed ventricular fibrillation during an episode of atrial fibrillation. Seven patients underwent electrophysiology study and arrhythmia induction, both before and during chronic amiodarone treatment. During a mean 30 months of follow-up (range 8 to 59 months), no recurrences of atrial fibrillation or ventricular fibrillation were noted. One patient had recurrent supraventricular tachycardia and underwent surgery. One had serious and five had minor side effects. Arrhythmia suppression was associated with prolongation of the anterograde accessory pathway (+38%, p less than 0.01) and atrial (+34%, p less than 0.01) effective refractory periods. Amiodarone also slowed the ventricular response to induced atrial fibrillation, prolonging the mean (+90%, p less than 0.01) and minimum (+104%, p = 0.01) R-R intervals. Thus, amiodarone is a safe and effective alternative for arrhythmia prevention if surgery is inadvisable or is not desired by the patient.

Programmed electrical stimulation in healed myocardial infarction using a standardized ventricular stimulation protocol

The diagnostic accuracy of programmed electrical stimulation was prospectively assessed in 111 patients with myocardial infarction (MI) with or without a history of spontaneous ventricular arrhythmias. In 29 patients neither ventricular tachycardia (VT) nor episodes of 10 premature ventricular depolarizations per hour was documented. Fifty patients had documented nonsustained VT and 32 had sustained monomorphic VT. One and 2 extrastimuli (twice diastolic threshold, 2 ms in duration) were given during sinus rhythm and ventricular pacing at 100, 120 and 140 beats/min in the right ventricular apex (part I). When this protocol failed to induce a sustained monomorphic VT, a third extrastimulus was introduced (part II). Repetitive ventricular responses were induced in all patients, and in 15 (14%) polymorphic ventricular arrhythmias requiring DC shock were induced. Incidence of initiation of sustained monomorphic VT and polymorphic ventricular arrhythmias requiring DC shock was related to the clinical arrhythmia and the stimulation protocol. In patients with documented sustained monomorphic VT, a third extrastimulus only increased the incidence of sustained monomorphic VT (68% to 94%), whereas in patients with documented nonsustained VT and without VT the incidence of both polymorphic and monomorphic arrhythmias increased by 7 to 12%. Sustained monomorphic VTs induced in patients without such a history were faster (p less than 0.01), depended on site of MI (p less than 0.05) and were more often preceded by nonsustained polymorphic VT (p less than 0.01) than in patients with documented sustained monomorphic VT.(ABSTRACT TRUNCATED AT 250 WORDS)

Dysrhythmias after direct-current cardioversion

The success rate of direct-current (DC) countershocks and postshock arrhythmias are of concern for the design of automatic devices. Results of 112 DC shocks for induced ventricular tachycardia/fibrillation (VT/VF) (n = 99) or atrial fibrillation (AF) were analyzed. Clinical and arrhythmia characteristics were related to the success rate of DC shocks as well as postshock arrhythmias. Sixty-one patients were men and 14 were women; mean age was 52 +/- 15 years. Coronary artery disease was present in 56 patients and cardiomyopathy in 4. The other patients had no apparent structural heart disease. The success rate of transchest DC shocks for VT and VF were identical. The first DC shock interrupted 80% of VT and VF episodes. All episodes were terminated by 4 or fewer DC shocks. A single DC shock changed morphologic pattern or rate of 4 episodes of VT. Asystole after VT/VF (1,900 +/- 960 ms) was longer than after atrial fibrillation (1,150 +/- 470 ms, p less than 0.01). VT/VF recurred (within 3 minutes) after 26 of 99 initially successful DC shocks, requiring repeat shocks in 2 cases. Sinus bradycardia (n = 18) or high degree atrioventricular block (n = 11) necessitated rate support pacing in 10 patients. Antiarrhythmic drugs did not prevent postshock tachycardias, but facilitated the development of bradycardias. In conclusion, reliable and continuous analysis of cardiac rhythm after discharge is mandatory to enable automatic devices to correct unsuccessful discharges or recurring VT/VF. In addition, demand pacing capability is desirable to prevent severe bradycardia after DC shocks in patients receiving antiarrhythmic drugs.

Importance of modes of electrical termination of ventricular tachycardia for the selection of implantable antitachycardia devices

Different implantable systems for electrical treatment of ventricular arrhythmias are available. Information about mode of termination of ventricular tachycardia (VT) helps to select the most appropriate electrical treatment for drug-resistant VT. During 158 electrophysiologic studies, the mode of termination of 215 episodes of VT was analyzed in 2 groups of patients. Group 1 consisted of 54 patients with documented monomorphic VT and group 2 of 46 patients with other documented or suspected ventricular arrhythmias. Eighty-two patients had coronary heart disease, 8 had other structural heart disease and 10 had idiopathic VT. Termination of VT was attempted using extrastimuli and overdrive pacing; direct-current (DC) shocks were given in case of syncopal VT. During 33 of 96 studies (34%) in group 1, DC shock was required to interrupt VT, compared with 45 of 62 studies (73%) in group 2 (p less than 0.001). This difference was a result of less frequent induction of immediately syncopal VT in group 1 (14 of 129 VTs, vs 40 of 86 in group 2, p less than 0.001). Non-syncopal VT could reliably and safely be terminated by pacing in 61%, irrespective of the clinical arrhythmia. Pacing-induced acceleration of VT occurred in 6% (single extrastimuli) to 36% (over-drive pacing) (mean 26%) of attempts. Subsequent DC shock was required in half of these cases. Immediate collapse after induction of VT was not related to the presence of heart disease, but was related to a combination of VT cycle length (shorter than 260 ms) and left ventricular ejection fraction (less than 40%). Antiarrhythmic drugs reduced the need for DC shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrophysiologic basis for the suppression by amiodarone of orthodromic supraventricular tachycardias complicating pre-excitation syndromes

Ten patients with refractory recurrent supraventricular tachycardia were found by electrophysiologic study to have bypass tracts and orthodromic atrioventricular reentrant tachycardia. All had failed to respond to conventional antiarrhythmic therapy and were therefore treated with oral amiodarone (1,600 to 2,000 mg/day for 2 weeks, then 800 to 1,200 mg/day for another 2 weeks with subsequent 200 to 600 mg/day maintenance doses). During or after the fourth week of therapy, electrophysiologic study was repeated. In 9 of 10 patients, supraventricular tachycardia could not be reinduced by programmed stimulation. In the remaining patient, nonsustained supraventricular tachycardia (greater than 10 beats, lasting less than 30 seconds) with a slower basic cycle length than that during the control period was provoked. Significant increases in the effective refractory period of the accessory pathway in both the anterograde (+26%, p less than 0.05) and retrograde (+40%, p less than 0.02) directions were noted, the magnitude of change being independent of the control effective refractory period. There were also significant increases in the effective refractory period of the right atrium (+24%, p less than 0.01) and the right ventricle (+15%, p less than 0.01) during long-term therapy with amiodarone. Over a mean follow-up period of 20 months, symptomatic control of the arrhythmia occurred in all patients; in only one patient treatment with amiodarone could not be continued because of side effects. These data establish the electrophysiologic basis for the effectiveness of amiodarone in the prophylactic control of refractory paroxysmal supraventricular tachycardia complicating the bypass tract syndromes.