Sleep Disordered Breathing and Arrhythmia Burden in Pacemaker Recipients

Background: Sleep disordered breathing (SDB), a common condition among patients with permanent pacemaker (PM), is associated with greater incidence of cardiac arrhythmias. Scarce availability of sleep laboratories and the high costs of nocturnal‐attended polysomnography limit the routine screening of patients with PM for SDB. We investigated whether a novel PM that utilizes variations in transthoracic impedance to record the fluctuations in breathing pattern and minute ventilation could be used to screen patients for SDB. Methods: Twenty patients who underwent dual‐chamber PM implantation were studied. The Talent 3 DR PM (SORIN Group Italy S.r.l., Milan, Italy) calculates apnea‐hypopnea index (AHI) by computing minute ventilation signal derived from transthoracic impedance measurements. Within a month after PM implantation, an in‐home respiratory monitoring was performed to evaluate the accuracy of PM‐derived AHI. Patients were followed for mean ± standard deviation, 487 ± 166 days. The PM was checked at each follow‐up visit to retrieve the information about recurrent arrhythmias. Results: Eleven patients were diagnosed with SDB by an in‐home respiratory monitoring. An AHI derived from an in‐home respiratory monitoring was similar to pacemaker‐derived AHI (27 ± 14 vs 16 ± 13 events/hour, P = 0.15). The cumulative incidence of cardiac arrhythmias, including atrial fibrillation, extrasystolic beats, sustained and nonsustained ventricular tachycardia, and supraventricular tachycardia was similar in patients with and without SDB. Conclusion: SDB is highly prevalent in patients with permanent pacemaker. Screening for SDB with Talent 3 DR PM may facilitate diagnosis and treatment of SDB. (PACE 2010; 33:1462–1466)     

Utilization of Defibrillators and Resynchronization Therapy at the Time of Evaluation at a Heart Failure and Cardiac Transplantation Center

Background: Internal cardioverter defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce mortality, but are underutilized in routine clinical practice. The use of these devices in patients at the time of an initial evaluation at an advanced heart failure and cardiac transplantation center is unknown. Methods: We retrospectively analyzed consecutive patients who were enrolled in a database examining parameters of cardiopulmonary exercise testing in chronic heart failure (CHF) patients at the time of an initial outpatient evaluation at a tertiary care center. Rates of ICD and CRT use in eligible patients were determined. Results: Two hundred two patients had an average age of 54 ± 13 years and an average peak oxygen consumption (pVO₂) of 12.5 ± 4.5 mL/kg/min. Of 97 patients eligible for an ICD only, 57% had an ICD at the time of evaluation. Sixty‐four percent of ICD‐eligible male patients had an ICD compared to 36% of ICD‐eligible female patients (P = 0.015). Of 105 patients meeting criteria for CRT, 54% had a CRT device. There was no difference between CRT use in eligible male and female patients. Conclusions: ICDs and CRT are underutilized in patients with severe CHF at the time of evaluation at a tertiary care center despite young age, objective functional limitation, and active consideration for advanced CHF therapies. Female patients have lower rates of ICD use than male patients. (PACE 2010; 988–993)     

Chemical synthesis and purification of proteins: a methodology

Classical stepwise solid-phase peptide synthesis (SPPS) has been used successfully for the synthesis of proteins up to 150 residues in length, although usually with poor yields and homogeneity. The major limitation has been the inability to separate chromatographically similar deletion and truncated impurities from the target sequence. We have developed a highly effective protocol for stepwise SPPS and‘one-step’purification of small proteins. To demonstrate the effectiveness of the methodology we synthesised the 101 residue chaperonin 10 protein from Rattus norvegicus (Rat Cpnl0) using three different chemical protocols. Highly homogeneous Rat Cpnl0 was obtained using an optimised synthetic strategy and one-step purification procedure (method C), involving (i) HBTU/HOBt activation, (ii) N-(2-chlorobenzyloxy-carbonyloxy)succinimide as capping agent and (iii) the incorporation of a reversible Fmoc-based chromatographic probe, derivatised with a lipophilic group for fast one-step RP purification, to give an overall yield of 9.6%. Analysis by ESI-MS indicated that the product was virtually free of deletion impurities, while RP-HPLC under four different conditions and CZE indicated that the protein was 100 and 84% pure, respectively. The spontaneous folding of Rat Cpnl0 into its biologically active form was found to correlate well with the degree of purity as assessed by chromatography, ESI-MS and sequencing, since 29 (A), 55 (B) and 81% (C) of correctly folded heptameric structure was obtained. The degree of homogeneity was also reflected in the ability of purified Rat Cpnl0 to facilitate the refolding of yeast enolase. © Munksgaard 1996.     

Reproducibility of the Dobutamine-Atropine Echocardiography Stress Test

To assess the reproducibility of dobutamine-atropine echocardiography testing, two studies (1 to 20 days apart [mean 3.3 days]) were performed in 23 patients with stable effort angina pectoris or chest pain. During the study, 20 (87%) patients were receiving beta blockers alone or combined with nitrates or calcium antagonists. Dobutamine was infused at doses of 10 μg/kg per minute every 3 minutes up to a maximum of 40 μg/kg per minute and this maximal dose was continued for 6 minutes. In patients not achieving 85% predicted maximal heart rate or myocardial ischemia, atropine (0.25–1 mg) was added and dobutamine continued for another 3 minutes, until either an adequate heart rate was achieved or the test was considered positive. During dobutamine infusion, electrocardiographic, echocardiographic, and blood pressure monitoring were obtained in each patient. Side effects including tremor, nausea, palpitation, dizziness, headache, and nonsustained ventricular tachycardia occurred in three patients. The same symptoms, but no ventricular tachycardia, developed during the same stage of the second test. Angina pectoris (eight patients), electrocardiographic changes (six patients), and ischemic wall-motion abnormalities (six patients) were observed at the same stage of the two tests. The mean values of heart rate, blood pressure, and rate-pressure product were comparable for each stage in duplicate tests. Our data show that pharmacological stress echocardiography using dobutamine-atropine has good reproducibility and provides a useful tool for assessing disease progression and the effects of therapeutic interventions in patients with coronary artery disease.     

Evaluation of Postinfarction Viable Myocardium at Jeopardy by Dobutamine Echocardiography and Myocardial Contrast Echocardiography

Both myocardial contrast echocardiography (MCE), obtained by intracoronary injection of sonicated Ioxaglate, and dobutamine echocardiography (DE) were performed before and after percutaneous transluminal coronary angioplasty (PTCA) in a patient with recent myocardial infarction, an occluded infarct related artery (IRA) and collateral flow. An opposite response to low and high dose dobutamine (increase and decrease in regional contractility, respectively) suggested the presence of viable myocardium at jeopardy in the infarcted area. This myocardial area was exclusively perfused by collateral circulation (demonstrated by MCE) supplied by an angiographically normal left coronary artery. After PTCA, right coronary artery flow was re-established and angiographically demonstrated collateral flow disappeared. MCE showed a normal right coronary artery perfusion bed and relevant overlap areas after left coronary MCE injection. Dobutamine echocardiography performed after PTCA demonstrated persistence of viability, but disappearence of myocardial ischemia.     

Synthetic peptides including acidic clusters as substrates of yeast casein kinase-2

The synthesis is reported of a series of glutamyl peptide analogs of the model substrate H-Ser-Glu-Glu-Glu-Glu-Glu-OH of casein kinase-2 (CK-2). A convenient HPLC method for the separation of slightly different acidic peptides is also reported. The site specificity of yeast casein kinase-2 (Y-CK2) is examined with the aid of synthesized peptide substrates.     

Postnatal development of intestinal endocrine cell populations in the water buffalo

The frequency and distribution of 11 endocrine cell populations were studied in the intestine of differently aged buffalo, grouped on the basis of diet: 2-d-olds (suckling), 5-mo-olds (weaning) and 5-y-olds (ruminant adult diet). The endocrine cell populations were identified immunocytochemically using antisera against 5-hydroxytryptamine (5-HT), somatostatin, gastrin, cholecystokinin (CCK), COOH-terminal octapeptide of gastrin/CCK, neurotensin, motilin, gastric inhibitory polypeptide (GIP), secretin, glucagon/glicentin (GLU/GLI) and polypeptide YY (PYY). In adult buffalos the regional distribution of endocrine cells is similar to that of other adult ruminants. During postnatal development, these cell types showed the following changes in their frequency and distribution: (1) 5-HT, neurotensin and gastrin/CCK immunoreactive cells (i.c.) showed a decrease in frequency with age; (2) somatostatin i.c. frequency remained stable with age; (3) motilin, GIP, secretin and CCK i.c. showed a slight increase in frequency with age; (4) GLU/GLI and PYY i.c. decreased in frequency with age in the small intestine, caecum and proximal colon and an increase in frequency in the rectum. It was hypothesised that the endocrine cell types, whose presence and localisation is substantially stable in all examined ages, probably contain substances that are strictly necessary for intestinal function. In contrast the hormones contained in the cell populations that decreased with age, are probably involved in physiological needs during the milk and weaning diet or play a role in intestinal growth.     

Low‐Risk Profile for Malignant Ventricular Arrhythmias and Sudden Cardiac Death after Surgical Ventricular Reconstruction

Background: Although it has been recently demonstrated that there was no significant difference in total survival and clinical outcomes between patients who underwent coronary artery bypass grafting (CABG) with or without surgical ventricular reconstruction (SVR), the question of whether or not SVR decreases the arrhythmic risk profile in this population has not been clarified yet. Objective: To determine the real incidence of sudden cardiac death (SCD) and sustained ventricular tachycardia/ventricular fibrillation (sustained VT/VF) in patients following CABG added to SVR and to define their clinical and echocardiographic parameters predicting in‐hospital and long‐term arrhythmic events (SCD + sustained VT/VF). Methods: Pre‐ and postoperative clinical and echocardiographic values as well as postoperative electrocardiogram Holter data of 65 patients (21 female, 63 ± 11 years) who underwent SVR + CABG were retrospectively evaluated. Results: Mean follow‐up was 1,105 ± 940 days. At 3 years, the SCD‐free rate was 98% and the rate free from arrhythmic events was 88%. Multivariate logistic analysis identified a preoperative left ventricular end‐systolic volume index (LVESVI) > 102 mL/m² (odds ratio [OR] 1.4, confidence interval [CI] 1.073–1.864, P = 0.02; sensitivity 100%, specificity 94%) and a postoperative pulmonary artery systolic pressure (PASP) > 27 mmHg (OR 2.3, CI 1.887–4.487, P = 0.01; sensitivity 100%, specificity 71%) as independent predictors of arrhythmic events. Conclusions: Our and previous studies report a low incidence of arrhythmic events in patients following SVR added to CABG, considering the high‐risk profile of the study population. A preoperative LVESVI > 102 mL/m² and a postoperative PASP > 27 mmHg had a good sensitivity and specificity in predicting arrhythmic events. (PACE 2010; 33:1054–1062)     

Catheter Induced Distal Intra-Hisian Right Bundle Branch Block in a Patient with Persistent Proximal Intra-Hisian Complete A-V Block

We describe a patient with complete intra-Hisian A-V block and narrow QRS who developed catheter-induced right bundle branch block during an electrophysiological study. Selective His bundle pacing was performed during complete intra-Hisian A-V block and right bundle branch block pattern; the distal His bundle pacing normalized the QRS complex, while a more proximal His bundle stimulation showed a right bundle branch block configuration with the persistence of the proximal intra-Hisian lesion responsible for the complete A-V block. These electrophysiological findings suggest that the catheter-induced right bundle branch block in our patient was due to a focal lesion in the distal part of the main His bundle. To our knowledge, this is the first report of documented multilevel lesions within the His bundle in man.