Complicated course of ischemic heart disease in a patient with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) can activate pathological routes which can lead to insulin resistance, development of atherosclerosis and hypertension. The combination of hypertension and OSA has an additive effect on the development of atherosclerosis. As a number of studies have revealed, that the incidence of OSA in patients with myocardial infarction is likely to be high.

METHODS AND RESULTS

We present a patient with acute myocardial infarction and no classical coronary artery disease risk factors: non-smoker, normal blood pressure, normal total and low-density lipoprotein cholesterol levels, borderline high-density lipoprotein cholesterol level, with good physical activity, no diabetes mellitus, no abdominal obesity, a negative family history. The only risk factor was untreated obstructive sleep apnea. The course of disease was complicated by subsequent in-stent restenosis and progression of atherosclerotic plaques, which led to the need for acute coronary artery bypass graft surgery complicated by consecutive in-anastomosis stenosis despite maximum cardiovascular therapy. One year of continuous positive airway pressure treatment was needed to stabilize his health condition, which is now stable for up to two years.

CONCLUSIONS

Given the complicated course of ischemic heart disease in patients with OSA, we believe that OSA diagnosis would be advisable each time these patients with symptoms of myocardial infarction, ischemic heart disease and OSA are examined. Even more important, however, is proper treatment of the OSA when it is present.

Segmental color Doppler myocardial imaging derived pre-ejection velocities are not clinically useful in the assessment of post-infarction scar transmurality

INTRODUCTION

The presence of a velocity in isovolumic contraction phase (Vivc) evaluated using tissue Pulse wave Doppler myocardial imaging (PWDMI) correlates with a transmural extent of scar after myocardial infarction. The possible clinical usefulness of Vivc evaluated using color Doppler myocardial imaging (CDMI) in detection of a scar after myocardial infarction extent in patients with coronary heart disease (CHD) and low LV systolic function remains to be clarified.

PATIENTS AND METHODS

57 patients with CHD (average LVEF 33.5±5%), examined echocardiographicaly (17-segment LV model, 689 segments evaluated) and by cardiac magnetic resonance. All segments were scanned for Vivc presence using CDMI. Vivc presence/absence was correlated with signs of a scar after MI in all segments and in akinetic segments separately.

RESULTS

We found significantly larger values of wall thickness (8.2±2,2 vs. 7.1±1.9, p<0.0001), significantly lower values of average late enhancement (LE) extent (1.32±1.78 vs. 1.66±1.98, p=0.041) and LE/wall thickness ratio (20.1±29.8 vs. 29.6±36.7, p=0.008) in segments with present Vivc. Vivc presence in a segment with an abnormal wall motion had a sensitivity of 72.9% and a specificity of 35.7% in recognizing a segment without a transmural scar (LE/ wall thickness ratio ≤75%). Vivc absence in a segment with an abnormal wall motion had a sensitivity of 72.7% and a specificity of 41.2% in recognizing a segment with a transmural scar (LE/wall thickness ratio ≥75%).

CONCLUSIONS

Isovolumic velocities evaluation assessed using color Doppler myocardial imaging is not applicable in a real-world clinical setting. The presence or absence of a velocity pattern during LV isovolumic contraction is not useful in in the assessment of a post-infarction scar transmurality.

Left ventricular mechanical activity detected by impedance recording

Aims

Recording and analysing impedance fluctuation along the cardiac cycle in the right (RV) and left ventricles (LV).

Methods and results

During a biventricular (BiV) implantation procedure, impedance was sequentially derived between the atrial ring electrode and either electrode (tip or ring) of the RV lead [transvalvular impedance (TVI)], and between the atrial ring and either the tip or ring electrode of a coronary sinus lead, positioned in a cardiac vein [left ventricle impedance (LVI)]. The LVI signal was also recorded by the implanted pacemaker at the 1 day and 3 months follow-ups. With intrinsic conduction, TVI showed an average increase of 53 ± 29 Ω during ventricular systole, whereas at the same time, LVI decreased by 45 ± 21 Ω (25 and 23 patients, respectively, out of 28 tested cases). Transvalvular impedance and LVI displayed a similar time course, which appeared to be related to the systolic timing in the RV and LV. Both LVI amplitude and duration decreased as a function of the cardiac rate. The LVI deflection started immediately after LV stimulation, and often anticipated the R-wave sensing after contralateral pacing. At the 3-month follow-up, LVI amplitude was decreased in 70% of cases and increased in the remainder, with a non-significant average change of −5 ± 85% with respect to the acute recordings.

Conclusion

Transvalvular impedance properties are consistent with the assumption of an inverse relationship with RV volume. Though LVI requires a different physical interpretation, the waveform duration might reflect the timing of LV myocardial contraction. In this hypothesis, the relationship between TVI and LVI could provide insight into the effects of BiV pacing on mechanical synchronization.

Performance of a New Leadless Implantable Cardiac Monitor in Detecting and Quantifying Atrial Fibrillation Results of the XPECT Trial

Background— Current methods for detecting atrial fibrillation (AF) have limited diagnostic yield. Continuous monitoring with automatic arrhythmia detection and classification may improve detection of symptomatic and asymptomatic AF and subsequent patient treatment. The study purpose was to quantify the performance of the first implantable leadless cardiac monitor (ICM) with dedicated AF detection capabilities.

Methods and Results— Patients (n=247) with an implanted ICM (Reveal XT, Medtronic Inc, Minneapolis, Minn) who were likely to present with paroxysmal AF were selected. A special Holter device stored 46 hours of subcutaneously recorded ECG, ICM markers, and 2 surface ECG leads. The ICM automatic arrhythmia classification was compared with the core laboratory classification of the surface ECG. Of the 206 analyzable Holter recordings collected, 76 (37%) contained at least 1 episode of core laboratory classified AF. The sensitivity, specificity, positive predictive value, and negative predictive value for identifying patients with any AF were 96.1%, 85.4%, 79.3%, and 97.4%, respectively. The AF burden measured with the ICM was very well correlated with the reference value derived from the Holter (Pearson coefficient=0.97). The overall accuracy of the ICM for detecting AF was 98.5%.

Conclusions— In this ICM validation study, the dedicated AF detection algorithm reliably detected the presence or absence of AF and the AF burden was accurately quantified. The ICM is a promising new diagnostic and monitoring tool for the clinician to treat AF patients independently of symptoms. Long-term studies are needed to evaluate the clinical benefits of the technology.

Clinical Trial Registration— clinicaltrials.gov Identifier NCT00680927.

Reproductive parasitism: male and female responses to conspecific and heterospecific intrusions at spawning in a mouth-brooding cichlid Ophthalmotilapia ventralis

A rare form of alternative reproductive behaviour without simultaneous parasitic spawning was observed in Ophthalmotilapia ventralis, a lekking mouth-brooding cichlid from Lake Tanganyika. Floater males attempted to sneak opportunistically into the territory to actively court the female, while the owner (bourgeois male) defended the territory against other potential intruders. Floater males had more body fat than territory owners and generally higher condition factors. In field experiments, the response of bourgeois males and courted females was tested towards floaters and egg predators (a catfish Synodontis multipunctatus) present in the territories. Territory owners responded aggressively particularly to floaters, and female responsiveness to bourgeois male courtship tended to decline when floaters were present. The potential influence of reproductive parasitism on sexual selection in mouth-brooding cichlids is discussed.

Prophylactic catheter ablation for the prevention of defibrillator therapy

BACKGROUND

For patients who have a ventricular tachyarrhythmic event, implantable cardioverter-defibrillators (ICDs) are a mainstay of therapy to prevent sudden death. However, ICD shocks are painful, can result in clinical depression, and do not offer complete protection against death from arrhythmia. We designed this randomized trial to examine whether prophylactic radiofrequency catheter ablation of arrhythmogenic ventricular tissue would reduce the incidence of ICD therapy.

METHODS

Eligible patients with a history of a myocardial infarction underwent defibrillator implantation for spontaneous ventricular tachycardia or fibrillation. The patients did not receive antiarrhythmic drugs. Patients were randomly assigned to defibrillator implantation alone or defibrillator implantation with adjunctive catheter ablation (64 patients in each group). Ablation was performed with the use of a substrate-based approach in which the myocardial scar is mapped and ablated while the heart remains predominantly in sinus rhythm. The primary end point was survival free from any appropriate ICD therapy.

RESULTS

The mortality rate 30 days after ablation was zero, and there were no significant changes in ventricular function or functional class during the mean (+/-SD) follow-up period of 22.5+/-5.5 months. Twenty-one patients assigned to defibrillator implantation alone (33%) and eight patients assigned to defibrillator implantation plus ablation (12%) received appropriate ICD therapy (antitachycardia pacing or shocks) (hazard ratio in the ablation group, 0.35; 95% confidence interval, 0.15 to 0.78, P=0.007). Among these patients, 20 in the control group (31%) and 6 in the ablation group (9%) received shocks (P=0.003). Mortality was not increased in the group assigned to ablation as compared with the control group (9% vs. 17%, P=0.29).

CONCLUSIONS

In this randomized trial, prophylactic substrate-based catheter ablation reduced the incidence of ICD therapy in patients with a history of myocardial infarction who received ICDs for the secondary prevention of sudden death. (Current Controlled Trials number, ISRCTN62488166 [controlled-trials.com].).

Use of intracardiac echocardiography to guide implantation of a left atrial appendage occlusion device (PLAATO)

BACKGROUND

Over 90% of thrombi in atrial fibrillation (AF) originate from the left atrial appendage (LAA). Patients with contraindications to anticoagulation are potential candidates for LAA occlusion using the Percutaneous Left Atrial Appendage Transcatheter Occlusion system (PLAATO, ev3 Inc., Plymouth, MN). Transesophageal echocardiography (TEE) is typically used to guide implantation.

OBJECTIVE

This study sought to examine the utility of intracardiac echocardiography (ICE) in providing adequate imaging guidance as an alternative to TEE during PLAATO implantation.

METHODS

The study group consisted of 10 patients who underwent PLAATO implantation with simultaneous TEE and ICE imaging guidance. ICE was used to perform the following tasks typically fulfilled by TEE: (1) verification of the absence of LAA thrombus, (2) identification of the LAA ostial dimension for device sizing, (3) guidance of transseptal puncture, (4) verification of the delivery sheath position, and (5) confirmation of location and stability of device before its irrecoverable release. The ability of ICE to perform these tasks was assessed from three separate positions: the standard right atrial (RA) position, within the coronary sinus (CS), and the right ventricular outflow tract.

RESULTS

ICE imaging of the LAA was optimal from within the CS, although imaging from the proximal pulmonary artery provided better visualization of the distal LAA in cross-section. The LAA dimensions, confirmation of the absence of LAA thrombus, proper positioning of the delivery sheath, verification of location and stability of the device obtained by ICE were consistent with findings from TEE.

CONCLUSION

Using nonconventional imaging planes, ICE imaging was able to perform the intraprocedural functions provided by TEE during implantation of the PLAATO left atrial appendage occlusion device.

Pacemaker and ICD lead extraction with electrosurgical dissection sheaths and standard transvenous extraction systems: results of a randomized trial

AIMS

The purpose of this prospective randomized study was to evaluate the safety and efficacy of transvenous pacemaker and implantable cardioverter-defibrillator (ICD) lead extraction with an electrosurgical dissection sheath (EDS) system in a single-centre experience. Methods Over 10 years, 462 patients have undergone transvenous lead extraction in our institution. From these, 120 consecutive patients (with 161 leads) were randomized to either radiofrequency (RF) current supported extraction or standard countertraction lead removal (60 patients in each arm, 96 men and 24 women). The mean age of randomized patients was 62.7 +/- 9.6 years. In 16 patients, we explanted 17 ICD leads. The average time from the date of implantation to the extraction procedure was 73.4 +/- 15.7 months. The most common reason for lead extraction was infection (95.6%). Results The complete extraction of 78 leads (93%) was achieved in the RF group and 56 leads (73%) with the standard transvenous lead extraction system by counter-traction (P < 0.01). Among these leads, we successfully removed nine of 10 ICD leads (90%) in the RF group and only four of seven ICD leads (57%) in the standard group. We also observed a significant reduction in the time taken for the successful removal of pacemaker and ICD leads using the RF system (9.6 +/- 6.2 min versus 21 +/- 9 min, P < 0.01). Partial success was achieved in six patients with the RF system and in 11 with standard sheaths. In those cases where we failed to remove the lead from the body we sent all but one patient to cardiac surgery. Serious complications were associated with the standard system in two patients, both of whom developed septic pulmonary embolization. Serious bleeding occurred in three patients, one with standard and two with the EDS lead extraction system.

CONCLUSION

The EDS extraction system is significantly more effective and quicker. However, the standard counter-traction method is still an effective alternative when used in a highly experienced centre.

Health-related quality of life relative to clinical outcomes in patients with atrial fibrillation treated with ventricular rate stabilisation pacing

AIMS

It is uncertain whether patient perception of atrial fibrillation (AF) is based on the fast ventricular rate as such or the irregularity of the ventricular responses. This trial was designed to confirm the effectiveness of a ventricular rate stabilisation (VRS) algorithm in reducing ventricular irregularity during permanent pacing in patients with AF and to assess the patient preference and effect on quality of life (QoL).

METHODS

In this multicentre single-blind randomised crossover trial, 184 patients with drug-refractory permanent (n=91) or paroxysmal (n=93) AF received a VVI(R) or DDD(R) pacemaker respectively and were paced in a randomised sequence with VRS on or off for two months. Clinical assessments (QoL, New York Heart Association (NYHA) classification, echocardiography, six-minute walk test and Holter recording) were carried out at baseline, at randomisation and after each crossover period. QoL assessment was performed using Aquarel, a new disease-specific QoL questionnaire for pacemaker patients, the Short Form 36 survey (SF-36), the Duke Activity Status Index (DASI) and the Symptom Checklist frequency and severity scores. At the end of the study patients preferences for VRS-on or VRS-off were recorded.

RESULTS

VRS pacing reduced ventricular irregularity without increasing the mean ventricular rate. VRS-on was preferred by 65.8% of patients with paroxysmal AF; patients with permanent AF had no preference. QoL did not show improvement during VRS pacing on any of the instruments.

CONCLUSION

VRS pacing is effective in reducing ventricular rhythm irregularity. QoL does not improve during VRS pacing but preference for VRS pacing appears particularly outspoken for patients with paroxysmal AF.

Rejection of atrial sensing artifacts by a pacing lead with short tip-to-ring spacing

AIMS

The ability of a new pacing lead design, with a 10 mm tip-to-ring spacing, to facilitate rejection of sensed far field R-waves and myopotentials was evaluated.

METHODS AND RESULTS

Measurements were performed in 66 patients. The occurrence of far field R-wave sensing and myopotential sensing was determined by means of the surface ECG and the ECG markers provided by the pacemaker. At an atrial sensitivity of 0.25 mV and an atrial blanking of 50 ms far field R-wave sensing was observed in 12 patients (18.2%) and at an atrial sensitivity of 1.0 mV no far-field R-wave sensing was observed. Myopotentials were sensed in 3 patients. In all patients the measured P-wave amplitude was at least twice the estimated amplitude of the far field R-wave at an atrial blanking of 50 ms.

CONCLUSION

The results from this study show that a small tip-to-ring spacing allows for programming of a high atrial sensitivity and short atrial blanking with an acceptably low risk for atrial artifact sensing.

Form Analysis Using Digital Signal Processing Reliably Discriminates Far-Field R Waves from P Waves

The correct detection of atrial arrhythmias by pacemakers is often limited by the presence of far-field R waves (FFRWs) in the atrial electrogram. Digital signal processing (DSP) of intracardiac signals is assumed to provide improved discrimination between P waves and FFRWs when compared to current methods. For this purpose, 100 bipolar and unipolar intracardiac atrial recordings from 31 patients were collected during pacemaker replacement and used for the off-line application of a novel DSP algorithm. Digital processing of the atrial intracardiac electrogram (IEGM) signals (8 bit, 800 samples/s) included filtering and calculation of the maximum amplitude and slope of the detected events. The form parameter was calculated, being the sum of the most negative value of the amplitude and that of the slope of the detected event. The algorithm collects form parameter data of P waves and FFRWs and composes histograms of these data. A sufficiently large gap between the FFRW and P wave histograms allows discrimination of these two signals based on form parameters. Three independent observers reviewed the reliability of classification with this algorithm. Sensitivity and specificity of FFRW detection were 99.63% and 100%, respectively, and no P waves were falsely classified. It can be concluded that this novel DSP algorithm shows excellent discrimination of FFRWs under off-line conditions and justify the implementation of this algorithm in future pacemakers for real-time discrimination between P waves and FFRWs. This method prevents false mode switching and allows correct and immediate intervention pacing for atrial tachyarrhythmias.

Female ambrosia beetles adjust their offspring sex ratio according to outbreeding opportunities for their sons

Recent studies on the effect of local mate competition (LMC) on sex ratios have focused on the effect of post-dispersal mating success by males. A higher proportion of males is expected to be produced as the potential for outbreeding increases. Here we demonstrate that males of a haplodiploid ambrosia beetle with LMC disperse to seek additional matings, and brood sex ratios increase with outbreeding opportunities in the field. Manipulations in the laboratory confirm that females produce more sons when the post-dispersal mating prospects of their sons are experimentally increased. This is the first study showing that male dispersal options may influence individual female sex allocation decisions in species with strong LMC.

Short-term results of substrate mapping and radiofrequency ablation of ischemic ventricular tachycardia using a saline-irrigated catheter

OBJECTIVES

We evaluated the safety and acute procedural efficacy of a combined electrophysiologic and anatomic approach to ablation of all inducible ventricular tachycardias (VT) during sinus rhythm using an irrigated radiofrequency (RF) ablation catheter.

BACKGROUND

Ventricular tachycardia associated with chronic myocardial infarction (MI) is frequently hemodynamically intolerable and associated with multiple electrocardiographic morphologies. Because traditional mapping techniques are contingent on hemodynamic stability for adequate VT mapping, VT ablation therapy for many patients has been disappointing.

METHODS

High-density electroanatomic mapping was performed during either sinus rhythm in 11 consecutive patients with a history of MI and ventricular arrhythmias. The RF ablation was performed using an irrigated-tip ablation catheter. All inducible VTs were targeted for catheter ablation during sinus rhythm.

RESULTS

The RF ablation lesions were placed in a linear fashion traversing the border zones of infarcted and normal tissue (mean of 3.4 linear lesions/patient). With this strategy, the target VT was eliminated in 9 of 11 patients (82%). Furthermore, when targeting all inducible monomorphic VTs, complete procedural success was achieved in 7 of 11 patients (64%). During the follow-up period (mean 13.1 +/- 1.9 weeks), spontaneous VT was only noted in the two patients with no acute procedural benefit.

CONCLUSIONS

By identifying potentially arrhythmogenic tissue during sinus rhythm, substrate mapping can guide the ablation of a majority of inducible VTs using an irrigated RF ablation catheter. This emerging therapeutic paradigm may be considered in the management of patients with multiple hemodynamically unstable monomorphic VTs.

Do woodpecker finches acquire tool-use by social learning?

Tool-use is widespread among animals, but except in primates the development of this behaviour is poorly known. Here, we report on the first experimental study to our knowledge of the mechanisms underlying the acquisition of tool-use in a bird species. The woodpecker finch Cactospiza pallida, endemic to the Galápagos Islands, is a famous textbook example of tool-use in animals. This species uses modified twigs or cactus spines to pry arthropods out of tree holes. Using nestlings and adult birds from the field, we tested experimentally whether woodpecker finches learn tool-use socially. We show that social learning is not essential for the development of tool-use: all juveniles developed tool-use regardless of whether or not they had a tool-using model. However, we found that not all adult woodpecker finches used tools in our experiments. These non-tool-using individuals also did not learn this task by observing tool-using conspecifics. Our results suggest that tool-use behaviour depends on a very specific learning disposition that involves trial-and-error learning during a sensitive phase early in ontogeny.

The evolution of bourgeois, parasitic, and cooperative reproductive behaviors in fishes

Among vertebrate classes, fishes exhibit by far the greatest variability in competitive and cooperative behaviors in male reproduction. Scramble competition between reproductive males is one possibility. Another possibility occurs when resources, mates, or locations can be monopolized, in which case males may invest in primary access to fertilizations by adopting a "bourgeois" strategy, or they may employ alternative mating tactics to evade the reproductive monopoly of other males. Adaptations in morphology, physiology, and behavior to bourgeois and alternative phenotypes are highly divergent. Here I review the functional characteristics that differ between bourgeois and parasitic phenotypes, and discuss the variability of alternative reproductive tactics at the levels of plasticity, determination, and selection. Examples will illustrate the importance of ecology, and will suggest that variation in reproductive tactics is largely adaptive. Behavioral solutions to competition for mates and fertilizations often involve agonistic behavior and conflict, but also cooperation among competitors (e.g., when subordinate males pay a price to bourgeois males for gaining access to fertilizable eggs). Application of molecular genetic tools has helped to uncover intricate sexual and social relationships in various fish species, including species that display some of the most complex reproductive and social patterns known among the vertebrates.

Behavioural time-energy budgets of cooperatively breeding Neolamprologus pulcher (Pisces: Cichlidae)

We estimated the energy expenditures resulting from helping behaviour in the cooperatively breeding cichlid N. pulcher by measuring the metabolic rates directly associated with specific social and territory maintenance behaviours of individual pair males and females, and their helpers, in a respirometer. In pair males, pair females and helpers, routine metabolism was raised on average 4.4, 3.8 and 3.6 times, respectively, during agonistic behaviour. Helpers spent 3.3 and 6.1 times routine metabolism, respectively, on submissive behaviour (tail quivering) and digging. These estimates of energy expenditure were combined with laboratory time budgets, obtained previously, to calculate behavioural time-energy budgets for pair members and helpers. Both groups spent on average 98.5% of total metabolism on routine and standard metabolism. With regard to the energy expended on specific behaviours, pair males invested almost exclusively in intrafamily agonistic behaviour, while pair females and helpers shared the investment in territory maintenance and direct brood care. The behavioural energy budget of helpers was strongly determined by their submissive behaviour. This serves to maintain the social status of the helpers within the family hierarchy and may therefore be regarded as 'paying for staying', which may also be true for direct brood care and other helper duties. We conclude that the substantial energy expenditures associated with helping behaviours are probably partly responsible for the reduced growth rates of helpers. This is the first study in which energy expenditures associated with specific helping behaviours have been measured in brood care helpers, and it provides the first estimate of total behavioural energy expenditure in a cooperatively breeding fish. (c) 1998 The Association for the Study of Animal Behaviour.

How do cuckoos find their hosts? The role of habitat imprinting

Although a number of hypotheses have been proposed for how European cuckoo, Cuculus canorus, females may find hosts belonging to their foster parents' species, clear evidence is lacking for any of them. Here, we propose 'habitat imprinting' as an alternative mechanism for host selection and provide evidence that cuckoos are able to remember acquired information about a familiar habitat. We hand-reared seven cuckoos in one of five different artificial habitats and tested them as adults in habitat choice experiments. In each test habitat, a pair of zebra finches, Taeniopygia guttuta, was presented as 'hosts'. We tested cuckoos of both sexes because the genotype of males may influence egg colour, and therefore egg mimicry; alternatively, habitat imprinting may be a general mechanism existing in both sexes but affecting egg mimicry only via females. Test cuckoos spent significantly more time looking at their respective familiar habitats than at other habitats in 1 of 2 test years. How long cuckoos were reared in the artificial habitats correlated positively with how long they spent in this habitat during the choice experiments. Additionally, test cuckoos remained longer with zebra finches that showed more nest-building behaviour but had lower levels of general activity, and they also observed these 'hosts' more frequently. If cuckoos choose to breed in habitats resembling those on which they were imprinted and search randomly for hosts in these habitats, they would increase their probability of parasitizing nests of their foster species. We propose that host specificity would be strengthened, however, if cuckoos use a sequence of several mechanisms, rather than just one, to find their hosts. (c) 1998 The Association for the Study of Animal Behaviour.