Role of the Atrial Rate as a Factor Modulating Ventricular Response during Atrial Fibrillation

Background: During atrial fibrillation (AF), RR interval histograms show different populations of predominant RR (pRR) intervals. These pRR intervals have been suggested to be multiples of the refractory period of the atrioventricular (AV) node or caused by the existence of a dual AV node physiology. In this study, the hypothesis that pRR intervals are related to the dominant atrial fibrillatory rate is tested. Methods: In this study, Holter electrocardiogram signals from 55 patients with persistent AF were analyzed. Number and position of pRR intervals were detected and compared with mean and standard deviation of the dominant atrial cycle length (DACL). In addition, effects of an enhancement of vagal activity and rate‐control treatments (β‐blockers and verapamil) were evaluated. Results: In all patients with more than one pRR interval and in 47% with one pRR interval, RR interval populations were statistically related with multiples of the DACL. During night activities and during β‐blockers treatment, mean ventricular rate was decreased (P < 0.01). This change was associated with a variation in the percentage of occurrences of each pRR (P < 0.01), whereas no statistical differences were present in the mean DACL or in the position of pRR intervals. A variation of the DACL due to verapamil was associated with a consistent modification in the position of the pRR intervals. Conclusion: The relation between pRR and multiples of the DACL during AF suggests that more probable RR intervals are caused by different conduction ratios of the atrial rate. (PACE 2010; 33:1510–1517)     

Left Ventricular Diastolic Dysfunction in Atrial Fibrillation: Predictors and Relation with Symptom Severity

Left Ventricular Diastolic Dysfunction in Atrial Fibrillation Background: Left ventricular diastolic dysfunction (LVDD) is common in the general population, but its prevalence in atrial fibrillation (AF), predictors for LVDD in AF and the association between LVDD and AF‐related symptom severity has not been well studied. Methods: In 124 consecutive patients (mean age 61 ± 11years, 60% male) with paroxysmal (n = 70) or persistent AF (n = 54) referred for AF catheter ablation, LVDD was evaluated according to current guidelines using transthoracic echocardiography. AF‐related symptom severity was quantified using the European Heart Rhythm Association score. Results: LVDD was present in 46 patients (37%). In uni‐ and multivariable regression analysis, age (OR 1.068 per year, 95% CI 1.023–1.115, P = 0.003) and persistent AF (OR 2.427 vs. paroxysmal AF, 95% CI 1.112–5.3, P = 0.026) were associated with LVDD. LVDD was found in 11% with mild AF symptoms (n = 27) as opposed to 44% in patients with moderate–severe AF symptoms (n = 97, P = 0.002). Thus, the OR for moderate–severe AF symptoms was 6.368 (1.797–22.568, P = 0.004) in the presence of LVDD. Conclusions: LVDD (1) occurs frequently in AF, (2) is associated with advancing age and AF progression and (3) is correlated with symptom severity in AF. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1073‐1077, October 2012)     

Asystole with Syncope Secondary to Hyperventilation in Three Young Athletes

We describe three athletes who had syncope after (case 1) or during (cases 2, 3) hyperventilation. During the episode, ECG showed prolonged sinus arrest. Clinical data and noninvasive investigations were normal and the phenomenon was not reproducible. Electrophysiological study after autonomic blockade allowed a prolonged intrinsic heart rate in case 1, and abnormal corrected sinus node recovery time in cases 1 and 2. During follow-up, symptomatic sinus arrest provoked by deep inspiration occurred in case 3. These cases document prolonged asystole of unknown etiology, secondary to hyperventilation, and probably caused by different vagally-mediated mechanisms.     

Ultrastructural and histochemical study on the interrenal cells of the male stickleback (Gasterosteus aculeatus, Teleostea), in relation to the reproductive annual cycle

The steroidogenic interrenal cells in the adrenal homologue of the male stickleback ( Gasterosteus aculeatus ) were studied in relation to the reproductive cycle by means of histological and ultrastructural observations, and using histochemical methods for the localisation of 3β-hydroxysteroid dehydrogenase (3βHSD) and 17β-hydroxysteroid dehydrogenase (17βHSD). To determine the various stages of the reproductive cycle, the testes were also examined by histological and histochemical methods (3βHSD). The results indicate that in this teleost the interrenal cells can undergo a cycle in which phases characterised by different cytological aspects are observed. During this cycle there is a renewal of organelles, in particular mitochondria and SER. Periodic degenerative processes are also found. Organelle cytology showed that the cell cycle has at least 3 different aspects during the year. An analogy with some cytological aspects of the adrenal zonation in mammals is possible. It is postulated that the interrenal gland activity could substitute or supplement androgen production by the testes.     

Reproductive prognosis after abdominal metroplasty in bicornuate or septate uterus: a life table analysis

Summary. Reproductive prognosis after abdominal metroplasty was assessed in 73 women with a septate and 71 with a bicornuate uterus who underwent metroplasty at the First Obstetric and Gynecologic Clinic of the University of Milan between 1972 and 1985. The overall cumulative 5-year delivery rates were respectively 70% and 73% in women with septate and bicornuate uterus, rising constantly with time. The number of previous miscarriages did not affect the reproductive prognosis: the 5-year probability of giving birth was 64% and 75% in the women with septate uterus and respectively fewer than two or two or more previous miscarriages, and the corresponding values were 66% and 73% in the bicornuate uterus subgroup. The miscarriage rate (about 20%) was similar with both types of malformation.     

EFFECTS OF FLUVOXAMINE AND CITALOPRAM IN MAINTAINING ABSTINENCE IN A SAMPLE OF ITALIAN DETOXIFIED ALCOHOLICS

A 16-week, randomized study was performed to test the efficacyof two selective serotonin reuptake inhibitors (SSRIs) fluvoxamineand citalopram, in decreasing relapse and craving in alcoholics,and to investigate possible differences in their clinical profile.After detoxification, each of the 81 patients (55 males and26 females) was randomly assigned to one of three groups: 23subjects did not receive any pharmacological treatment, 25 weretreated with fluvoxamine, 150mg/day, and 33 with citalopram.20mg/day. All patients received standard cognitive-behaviouraltherapy. Craving was assessed twice a month using a 10-stepscale. Every intake of alcohol was considered a relapse andthe subject was taken out of the study. At the end of the study,both the fluvoxamine and citalopram groups showed a statisticallyhigher rate of continuous abstinence (63.6 and 60.7%, respectively)compared to the group without pharmacological treatment (30.4%).Relapse severity did not differ among the three groups. Onlycitalopram showed a significant effect on craving throughoutthe study period. This study confirmed the efficacy of SSRIsas an adjunct to psychotherapy to prevent relapse in alcoholics.The relationship between the effects of these SSRIs on abstinenceand craving, as well as the differences between their profiles,are discussed.     

Adaptive Rate Pacing Controlled by Right Ventricular Preejection Interval for Severe Refractory Orthostatic Hypotension

A 72-year-old African-American man with frequent recurrent syncope was found to have severe refractory orihostatic hypotension with concomitant supine hypertension. Pharmacotherupy was successful in controlling his supine hypertension but was unable to resolve his severe orihostatic hypotension. Temporary fixed rate tachypacing was only minimally effective in preventing syncope during upright tilt, while variable rate pacing based on degree of blood pressure fall was far superior. Following these observations, an adaptive rate pacing system controlled by right ventricular preejection interval was implanted (Precept DR Model 1200). The system adequately sensed the patient's fall in blood pressure when sitting or standing and augmented its rate accordingly, thus preventing syncope. While supine, the pacing rate fell to 60 ppm, thereby, avoiding an exacerbation of his concomitant supine hypertension. Over a 3-nionth follow-up period, he has had no further orthostatic or syncopal episodes. We conclude that adaptive rate pacing using right ventricular preejection interval may be an effective treatment for severe refractory orthostatic hypotension.     

Internal Cardioversion of Chronic Atrial Fibrillation in Patients

Transvenous internal cardioversion of chronic AF using a right atrium (RA) coronary sinus (CS) vector requires more energy than cardioversion of paroxysmal AF. Chronic AF is not terminated in 25% of patients using biphasic shocks up to 10 J. We therefore evaluated efficacy, safety, and tolerability of internal cardioversion using a "unipolar' configuration (RA to skin patch) and biphasic shocks in patients with long-lasting AF and different heart disease. In each patient, biphasic R have synchronous shocks were delivered between a large defibrillating surface area electrode in the RA and a skin patch in the left prepectoral position. Defibrillation protocol started with a test shock of 0.4 J. Shocks were repeated and increased until termination of AF or a maximum of 34 J. Sedation was used when the patient described the shock as painful. This study included 11 patients with a mean age of 67 ± 8 years (range 56–83). AF duration was ± 1 month in all patients with a mean duration of 11 ± 11 months (range 2–36). Underlying heart disease was present in all patients and the mean left atrial dimension was 43 ± 9 mm (range 26–57). AF was terminated in 10 of 11 patients (91 %) with a mean delivered energy of the successful shocks of 18.7 ± 8.7 J (median energy 16.9 J; range 7.3–32.5) and a mean leading edge voltage of 564 ± 129 V. The mean shock impedance at the defibrillation threshold was 71 ± 13 Ω, (range 59–103). A total of 131 shocks were delivered without any complication and proarrhythmia episodes. We conclude that low energy "unipolar" internal cardioversion is a simple, safe, and effective technique for termination of chronic AF in patients with heart disease. The procedure is often tolerated under light sedation.