Impact of asynchronous ventricular activation on pro-inflammatory cytokines and oxidative stress in paced patients.
Explore the source record for details and available documents.
Cardiac Pacing, Artificial↗
Biomedical subjects
S I Chrysostomakis
Publications and source records attributed to S I Chrysostomakis.
Sensing issues related to the clinical use of implantable loop recorders.
AIMS: The newer insertable loop recorder device (Reveal Plus 9526, Medtronic Inc, Minneapolis MN, U.S.A.) is equipped with auto-activation capabilities. In this study we investigated whether the new device encounters sensitivity problems in the form of oversensing or undersensing. We also tested whether body position changes influence the sensed electrogram's amplitude, therefore affecting the device's autosensing ability. METHODS AND RESULTS: We enrolled 32 patients aged 58.1+/-11.7 years with a loop recorder implanted either in the left parasternal or in the heart's apex area, to investigate undiagnosed syncopal episodes after initial assessment. During the follow-up period (5.7+/-2.7 months), that began 6 months after the device implantation, we analysed 284 auto-recorded episodes (103 undersensed and 181 correctly sensed). No oversensing episodes were recorded. THE RECORDED QRS amplitude in five different body positions: supine, left and right lateral, sitting and standing was measured. No statistically significant changes were observed in the different postures. Even when patients were divided into subgroups according to implant site or the occurrence of undersensing episodes, no significant inter- or intra-group differences of the sensed electrogram were observed. CONCLUSION: Undoubtedly this device is the current gold standard for the diagnosis of unexplained syncope. In the population we studied though, the device faced undersensing problems. Consequently, the device should be equipped with more advanced software for QRS morphology recognition, to improve the diagnostic accuracy of the recorder.
Adult↗
Effect of acute atrial fibrillation on phasic coronary blood flow pattern and flow reserve in humans.
AIMS: To assess the effect of experimentally induced atrial fibrillation on coronary flow in humans. METHODS AND RESULTS: In 16 patients (10 men, mean age 43+/-13 years) with normal coronary vessels, baseline and hyperaemic blood pressure and Doppler phasic coronary flow velocity were measured, using a 0.014 inch intracoronary Doppler flow wire, during sinus rhythm, experimentally induced atrial fibrillation, and right atrial pacing at a similar heart rate to that during atrial fibrillation. Coronary flow velocity integral per minute increased significantly during both right atrial pacing and atrial fibrillation compared to sinus rhythm, but during right atrial pacing the increase was greater (85+/-43% vs 52+/-25%, P<0.001). This difference persisted even after correction for the product of heart rate and blood pressure (1.15+/-0.51 vs 0.97+/-0.46, respectively, P<0.02). In a further 12 paced patients (seven men, mean age 54+/-10 years) with complete atrioventricular block the induction of atrial fibrillation (atrial fibrillation with regular RR interval) caused no significant changes in coronary flow velocity variables. CONCLUSIONS: Acute atrial fibrillation in humans causes an increase in coronary flow that is, however, insufficient to compensate for the augmented myocardial oxygen demand, mainly because of the irregularity in the ventricular rhythm that exists during atrial fibrillation.
Acute Disease↗
Implantable loop recorder undersensing mimicking complete heart block.
The newer implantable loop recorders recently introduced (Reveal Plus. Medtronic Inc, Minneapolis, MN, U.S.A.). equipped with auto activation capabilities, are expected to expand our diagnostic abilities in the investigation of syncopal episodes. The case presented here is that of a man with pre-syncopal and syncopal episodes, without organic heart disease, in whom the device was auto-activated due to undersensing and the recorded strip imitated complete heart block. Increased attention should be given by the interpreter of the device's recordings to avoid false positive diagnoses that might lead to serious therapeutic actions.
Aged↗
Assessment of myocardial adrenergic innervation in patients with sick sinus syndrome: effect of asynchronous ventricular activation from ventricular apical stimulation.
OBJECTIVE: To investigate ventricular sympathetic innervation in patients with sick sinus syndrome and to detect regional deterioration of adrenergic innervation caused by asynchronous ventricular activation from right ventricular pacing. DESIGN: Prospective controlled study. SETTING: Tertiary cardiac referral centre. PATIENTS: 22 patients with sick sinus syndrome and indications for permanent dual chamber pacing; 20 healthy individuals as controls. INTERVENTIONS: All patients underwent myocardial imaging with planar and single photon emission computed tomography (SPECT) after an intravenous infusion of 5 mCi 123I-meta-iodobenzylguanidine (123I-MIBG) before and after pacemaker implantation. A SPECT thallium201 myocardial study was done during the same week as the 123I-MIBG study in all patients. MAIN OUTCOME MEASURES: The heart to mediastinum (H/M) ratio and washout rate were calculated during the 123I-MIBG study to assess the global cardiac sympathetic activity; the aim of the SPECT study was to investigate the regional distribution of adrenergic innervation. RESULTS: The H/M ratio was significantly smaller in the patients with sick sinus syndrome than in the controls (p < 0.001). In sick sinus syndrome there were regional adrenergic innervation defects, mostly in the inferior and apical walls. After a medium term pacing period, a redistribution of 123I-MIBG uptake was detected, with deterioration of adrenergic innervation in the inferior, apical, and posterior walls. The thallium201 myocardial perfusion study showed no change after three months of permanent pacing. CONCLUSIONS: Patients with sick sinus syndrome have global and regional disturbances of the adrenergic innervation of the left ventricular myocardium. These seem to deteriorate as a result of asynchronous electrical activation. The clinical significance of this finding requires further investigation.
3-Iodobenzylguanidine↗
Myocardial perfusion in patients with permanent ventricular pacing and normal coronary arteries.
OBJECTIVES: The purposes of this study were to test the specificity of dipyridamole myocardial perfusion scintigraphy in patients with permanent ventricular pacing (PVP) and to evaluate coronary blood flow and reserve in these patients. BACKGROUND: Permanent ventricular pacing is associated with exercise perfusion defects on myocardial scintigraphy in the absence of coronary artery disease (CAD). On the basis of studies in patients with left bundle brunch block, coronary vasodilation with dipyridamole has been proposed as an alternative to exercise testing for detecting CAD in paced patients, but this approach has never been tested. METHODS: Fourteen patients with a PVP and normal coronary arteries underwent stress thallium-201 scintigraphy and cardiac catheterization. In these patients and in eight control subjects, coronary flow velocities were measured in the left anterior descending coronary artery (LAD) and in the dominant coronary artery before and after adenosine administration. RESULTS: In the paced patients, coronary flow velocities in the LAD and in the dominant coronary artery were significantly lower than those in the control subjects. In addition, seven patients showed perfusion defects on dipyridamole thallium-201 single-photon emission computed tomography, with a specificity of 50% for this test. The defect-related artery in these patients had lower coronary flow reserve (2.6 +/- 0.5) as compared with those without perfusion defects (3.9 +/- 1.0, p < 0.05) or the control group (3.5 +/- 0.5, p < 0.05). CONCLUSIONS: Permanent ventricular pacing is associated with alterations in regional myocardial perfusion. Furthermore, abnormalities of microvascular flow, as indicated by reduced coronary flow reserve in the defect-related artery, are at least partially responsible for the uncertain specificity of dipyridamole myocardial perfusion scintigraphy.
Aged↗
Effects of asynchronous ventricular activation on myocardial adrenergic innervation in patients with permanent dual-chamber pacemakers; an I(123)-metaiodobenzylguanidine cardiac scintigraphic study.
AIMS: To evaluate myocardial sympathetic innervation abnormalities in patients with DDD pacemakers for complete heart block. METHODS: We studied 39 patients, chronically paced in DDD mode because of complete atrioventricular block. Twenty-three healthy individuals served as a control group. All patients underwent planar and single-photon emission computed tomography (SPECT) myocardial imaging 4 h after intravenous infusion of 185 MBq I(123)-MIBG. The heart to mediastinum ratio was calculated to quantify cardiac I(123)-MIBG accumulation, while the SPECT study was performed to investigate the regional distribution of adrenergic innervation. All patients underwent a SPECT thallium(201)myocardial study during the same week as the I(123)-MIBG study. RESULTS: The heart to mediastinum ratio was significantly smaller in paced patients than in the controls (P<0.001). 89.7% of paced patients had regional abnormalities of I(123)-MIBG uptake, mainly in the inferior (92.3%) and apical (38.5%) wall. 46.2% of paced patients had regional perfusion defects, also mainly in the inferior (46.2%) and apical (10.3%) wall. Neither the I(123)-MIBG abnormalities nor the perfusion defects were related to the duration of pacing. CONCLUSIONS: Stimulation from the apex of the right ventricle leads to regional disturbances of the adrenergic innervation of the left ventricular myocardium, as assessed by I(123)-MIBG activity.
3-Iodobenzylguanidine↗
Atrial and ventricular refractoriness in paced patients; circadian variation and its relationship to autonomic nervous system activity.
AIMS: To examine whether atrial and ventricular effective refractory periods exhibit circadian variation and whether the latter is correlated with fluctuations in autonomic nervous system tone. METHODS AND RESULTS: We studied 24 patients aged 67.1 +/- 9.6 years, 11 of whom were paced for complete heart block and 13 for sick sinus syndrome. Atrial and ventricular effective refractory periods were measured bihourly over a 24-h period, using the pacemaker programming capabilities, at basic cycle lengths of 600 ms and 500 ms. During the same time period we evaluated autonomic nervous system activity in patients paced for complete heart block, expressed by spectral power indexes in low frequency and high frequency areas of heart rate variability. Atrial and ventricular effective refractory periods showed significant circadian variation at both basic cycle lengths, with the highest values occurring between 22:00 and 06:00. At times, the atrial and ventricular effective refractory periods of the patients with sick sinus syndrome differed significantly from those with complete heart block. Furthermore, atrial and ventricular effective refractory periods in patients with complete heart block exhibited a strong negative correlation with the low frequency/high frequency ratio. CONCLUSION: Our data show that atrial and ventricular effective refractory periods in DDD paced patients exhibit significant circadian variation that is strongly correlated with variations in autonomic nervous system activity in patients with complete heart block.
Aged↗
The role of laser-induced fluorescence in myocardial tissue characterization: an experimental in vitro study.
OBJECTIVE: The fluorescence of tissue when stimulated by a laser beam is a well-known phenomenon. The resulting emission spectra depend on the biochemical and structural composition of the tissue. In this study, we examined the spectra of laser-induced fluorescence emitted by myocardial tissue. METHODS: We used an argon-ion laser to stimulate the myocardium of 20 intact sheep hearts. For each spectral emission, we calculated the intensity in specific regions in order to characterize the spectra and to reveal intercavitary and intracavitary morphologic differences. RESULTS: The statistical analysis showed significant differences in the emission spectra intensity between atria and ventricles. The intensity was higher in the atria than in the ventricles (p < 0.001). The atrial emission spectra were morphologically different from those of the ventricles. There was no difference in the intensity or morphology of emission spectra within each chamber. All measurements showed good reproducibility after a short period of time. CONCLUSIONS: Laser-induced fluorescence of myocardial tissue seems to have the characteristics necessary for tissue recognition. This might prove useful in identifying cardiomyopathies and transplant rejection, as well as for myocardial mapping, assisting electrophysiologists in discovering fibrotic arrhythmogenic foci.
Animals↗
Insertable loop recorder in unmasking the cause of syncope.
During the last few years closed loop recorders are being used increasingly in the investigation of unexplained syncope. Our patient had a 5-year history of pre- and syncopal episodes in which the usual invasive and noninvasive tests were nondiagnostic. Finally, a loop recorder was implanted that revealed the cause of the syncope a few days after implantation: a fast, sustained, ventricular tachycardia originating from the right ventricular outflow tract. Loop recorders will undoubtedly contribute toward the decrease in the percentage of undiagnosed syncope cases and possibly to the reduction of the investigation cost.
Electrocardiography↗
Amiodarone, sotalol, or propafenone in atrial fibrillation: which is preferred to maintain normal sinus rhythm?
UNLABELLED: This randomized study compared the efficacy and safety of amiodarone, propafenone and sotalol in the prevention of atrial fibrillation. METHODS: The population consisted of 214 consecutive patients (mean age 64 +/- 8 years, 106 men) with recurrent symptomatic atrial fibrillation. After restoration of sinus rhythm, patients were randomized to amiodarone (200 mg/day), propafenone (450 mg/day) or sotalol (320 +/- 20 mg/day). Follow-up evaluations were conducted at 1, 2, 4 and 6 months, and at 3-month intervals thereafter. The proportion of patients developing recurrent atrial fibrillation and/or experiencing unacceptable adverse effects was measured in the three groups by the Kaplan-Meier method. RESULTS: Recurrent atrial fibrillation occurred in 25 of the 75 patients treated with amiodarone compared to 51 of the 75 patients treated with sotalol and 24 of the 64 patients treated with propafenone. Fourteen patients treated with amiodarone, five with sotalol, and one with propafenone experienced adverse effects while in sinus rhythm, necessitating discontinuation of treatment (P < 0.001 for amiodarone and propafenone vs sotalol). The difference between amiodarone and propafenone was statistically nonsignificant when all events were included in the analysis. However, if the analysis was limited to recurrent atrial fibrillation events, amiodarone was more effective than propafenone (P < 0.05). CONCLUSIONS: Amiodarone and propafenone were superior to sotalol in maintaining long-term normal sinus rhythm in patients with atrial fibrillation. Amiodarone tended to be superior to propafenone, though its long-term efficacy was limited by adverse side effects.
Administration, Oral↗
Effect of pericardial pressure on human coronary circulation.
A 52-year-old patient underwent percutaneous balloon pericardiotomy because of rapid fluid accumulation. During the procedure, we calculated the amount of blood flow to the nondiseased left anterior descending coronary artery while pericardial pressure was gradually increased by the infusion of warmed normal saline solution. Coronary vasodilator reserve was assessed by intracoronary adenosine. With increasing pericardial pressure, there was a continuous decline in coronary blood flow, due to an increase in coronary vascular resistance, and an unaffected hyperemic response throughout. The maximal hyperemic flow was far less under increased pericardial pressure than at normal pressure, which implies an augmented susceptibility to myocardial ischemia.
Blood Flow Velocity↗
Reproducibility of time-domain indexes of heart rate variability in patients with vasovagal syncope.
The aim of this study was to examine whether the indexes of heart rate variability (HRV) are stable from day-to-day in patients with vasovagal syncope and whether the stability of the HRV indexes is linked with that of the clinical results of the tilt test. Nineteen patients with a history of syncopal episodes and a positive tilt test underwent a second test 1 week later. Of these, 11 (group P-P) also had a positive second test, whereas 8 (group P-N) had a negative second test. Fifteen healthy volunteers served as a control group. Five time domain indexes were derived: the mean of all coupling intervals between normal beats (mean NN), the SD about the mean of all coupling intervals between normal beats (SDNN), the mean of all 5-minute standard deviations of NNs (SD), the proportion of adjacent normal RR intervals differing by >50 ms (pNN50), the root-mean-square of the difference between successive RRs (rMSSD) and the standard deviations of 5-minute mean NN intervals (SDANN). The control group showed good reproducibility of all HRV indexes (slope 0.86 to 0.97). The syncopal patients taken as a whole had significantly less reproducibility than the controls in the pNN50 parameter. This difference was due entirely to the patients in the P-N group, who had a remarkable lack of reproducibility in both the pNN50 and rMSSD measures (slope pNN50, 0.52; rMSSD, 0.78), whereas the P-P group had a reproducibility of all HRV indexes, which was no different from that in controls (slope 0.83 to 1.04). In patients with vasovagal syncope, certain HRV measures that express parasympathetic tone did not show the high reproducibility found in normal subjects. Syncopal patients who lack reproducibility in these HRV parameters also show a lack of reproducibility in the clinical result of tilt testing.
Analysis of Variance↗
AAIR versus DDDR pacing in patients with impaired sinus node chronotropy: an echocardiographic and cardiopulmonary study.
The aim of this study was to compare AAIR and DDDR pacing at rest and during exercise. We studied 15 patients (10 men, age 65 +/- 6 years) who had been paced for at least 3 months with activity sensor rate modulated dual chamber pacemakers. All had sick sinus syndrome (SSS) with impaired sinus node chronotropy. The patients underwent a resting echocardiographic evaluation of systolic and diastolic LV function at 60 beats/min during AAIR and DDDR pacing with an AV delay, which ensured complete ventricular activation capture. Cardiac output (CO) was also measured during pacing at 100 beats/min in both pacing modes. Subsequently, the oxygen consumption (VO2AT) and VO2AT pulse at the anaerobic threshold were measured during exercise in AAIR mode and in DDDR mode with an AV delay of 120 ms. The indices of diastolic function showed no significant differences between the two pacing modes, except for patients with a stimulus-R interval > 220 ms, for whom the time velocity integral of LV filling and LV inflow time were significantly lower under AAI than under DDD pacing. At 60 beats/min, CO was higher under AAI than under DDD mode only when the stimulus-R interval was below 220 ms. For stimulus-R intervals longer than 220 ms, and also during pacing at 100 beats/min, the CO was higher in DDD mode. The stimulus-R interval decreased in all patients during exercise. The time to anaerobic threshold, VO2AT, and VO2AT pulse showed no significant differences between the two pacing modes. Our results indicate that, at rest, although AAIR pacing does not improve diastolic function in patients with SSS, it maintains a higher CO than does DDDR pacing in cases where the stimulus-R interval is not excessively prolonged. On exertion, the two pacing modes appear to be equally effective, at least in cases where the stimulus-R interval decreases in AAIR mode.
Aged↗
Left atrial appendage function during DDD and VVI pacing.
OBJECTIVE: To examine, using transoesophageal echocardiography, the possible disturbances of left atrial appendage function during VVI and DDD pacing in patients with a normal atrium paced with a dual chamber system. DESIGN: Randomised controlled trial. SETTING: Tertiary care centre. PATIENTS: 22 patients (mean age 68 (SD 6) years) who had been paced with dual chamber pacemakers for at least six months. Exclusion criteria were valvar disease, cardiomyopathy, hypertension, and diabetes mellitus. INTERVENTIONS: All patients underwent a transoesophageal echocardiographic evaluation of left atrial appendage function under DDD and VVI modes in random order. Measurements were made after at least two months' pacing in each mode. MAIN OUTCOME MEASURES: Echocardiographic indices of left atrial appendage flow under both pacing modes. RESULTS: All 22 patients had higher emptying and filling flow velocities under DDD than under VVI mode. The filling and emptying flow velocity integrals were also significantly higher under DDD mode (P < 0.001, P = 0.019). CONCLUSIONS: Left atrial appendage function, as reflected in indices of emptying and filling assessed by transoesophageal echocardiography, is significantly different with DDD than with VVI pacing. This may explain the higher incidence of thromboembolic episodes in patients paced under VVI mode.
Aged↗
Is there increased sympathetic activity in patients with mitral valve prolapse?
The aim of this study was to investigate autonomic nervous system tone in patients with mitral valve prolapse (MVP). Heart rate variability (HRV) was assessed from 24-hour ambulatory Holter recordings in 28 patients with primary MVP and in 28 age and sex matched normal control subjects in a drug-free state. Sixteen of the MVP patients were symptomatic and 12 asymptomatic. Spectral HRV was calculated in terms of low (LF: 0.06-0.15 Hz) and high (HF: 0.15-0.40 Hz) frequency components using fast Fourier transform analysis, and the ratio LF/HF was calculated. Spectral analysis of HRV showed that the MVP patients, taken as a single group, had lower HF and LF and a higher LF/HF ratio than the controls. No significant difference in HRV was found between the 16 symptomatic and the 12 asymptomatic patients, but the symptomatic patients had a significantly higher LF/HF ratio than the controls. Our observations suggest that, during normal daily activities, patients with MVP experience a significant deviation in autonomic nervous system tone with predominance of the sympathetic branch. This predominance is more marked in symptomatic patients.
Activities of Daily Living↗
The contribution of isoproterenol to the prolonged tilt test.
In this study the tilt test, in combination with isoproterenol administration, was used to investigate 44 patients with unexplained syncope. The reproducibility of the method was studied in a group of 32 patients who underwent a second test. The administration of isoproterenol during the test increased the sensitivity of the method from 52 to 70% and the reproducibility of a positive result from 61% to 83%, at the expense of a small decrease in specificity (from 100% to 93%). Isoproterenol should thus be considered an essential part of the method, although the low reproducibility of specific types of haemodynamic response limits its value in the choice and the follow up of treatment in individual cases.
Blood Pressure↗