The integrated understanding of structural and functional connectomes in depression: A multimodal meta-analysis of graph metrics

BACKGROUND

From the perspective of information processing, an integrated understanding of the structural and functional connectomes in depression patients is important, a multimodal meta-analysis is required to detect the robust alterations in graph metrics across studies.

METHODS

Following a systematic search, 952 depression patients and 1447 controls in nine diffusion magnetic resonance imaging (dMRI) and twelve rest state functional MRI (rs-fMRI) studies with high methodological quality met the inclusion criteria and were included in the meta-analysis.

RESULTS

Regarding the dMRI results, no significant differences of meta-analytic metrics were found; regarding the rs-fMRI results, the modularity and local efficiency were found to be significantly lower in the depression group than in the controls (Hedge's g = -0.330 and -0.349, respectively).

CONCLUSION

Our findings suggested a lower modularity and network efficiency in the rs-fMRI network in depression patients, indicating that the pathological imbalances in brain connectomes needs further exploration.

LIMITATIONS

Included number of trials was low and heterogeneity should be noted.

Shotgun metagenomics reveals both taxonomic and tryptophan pathway differences of gut microbiota in bipolar disorder with current major depressive episode patients

BACKGROUND

The microbiome-gut-brain axis, especially the microbial tryptophan biosynthesis and metabolism pathway (MiTBamp), is closely connected to bipolar disorder with current major depressive episode (BPD).

METHODS

We performed shotgun metagenomics sequencing (SMS) of faecal samples from 25 BPD patients and 28 healthy controls (HCs). Except for the microbiota taxa and MiTBamp analyses, we also built a classification model using the Random Forests (RF) and Boruta algorithm to find the microbial biomarkers for BPD.

RESULTS

Compared to HCs, the phylum Bacteroidetes abundance was significantly reduced, whereas that of the Actinobacteria and Firmicutes were significantly increased in BPD patients. We also identified 38 species increased and 6 species decreased significantly in the BPD group. In the MiTBamp, we identified that two Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) (K00658 and K00837) were significantly lower in the BPD, and five KOs (K01696, K00382, K00626, K01667, and K03781) were significantly higher in the BPD group. We also identified significant genera and species which were closely related to these KOs. Finally, RF classification based on gut microbiota at the genus level can achieve an area under the receiver operating characteristic curve of 0.997.

LIMITATIONS

The features of cross-sectional design, limited sample size, the heterogeneity of bipolar disorders, and a lack of serum/plasma tryptophan concentration measurements.

CONCLUSIONS

The present findings enable a better understanding of changes in gastrointestinal microbiome and MiTBamp in BPD. Alterations of microbes may have potential as biomarkers for distinguishing the BPD patients form HCs.

Shotgun metagenomics reveals both taxonomic and tryptophan pathway differences of gut microbiota in major depressive disorder patients

BACKGROUND

The microbiota-gut-brain axis, especially the microbial tryptophan (Trp) biosynthesis and metabolism pathway (MiTBamp), may play a critical role in the pathogenesis of major depressive disorder (MDD). However, studies on the MiTBamp in MDD are lacking. The aim of the present study was to analyze the gut microbiota composition and the MiTBamp in MDD patients.

METHODS

We performed shotgun metagenomic sequencing of stool samples from 26 MDD patients and 29 healthy controls (HCs). In addition to the microbiota community and the MiTBamp analyses, we also built a classification based on the Random Forests (RF) and Boruta algorithm to identify the gut microbiota as biomarkers for MDD.

RESULTS

The Bacteroidetes abundance was strongly reduced whereas that of Actinobacteria was significantly increased in the MDD patients compared with the abundance in the HCs. Most noteworthy, the MDD patients had increased levels of Bifidobacterium, which is commonly used as a probiotic. Four Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologies (KOs) (K01817, K11358, K01626, K01667) abundances in the MiTBamp were significantly lower in the MDD group. Furthermore, we found a negative correlation between the K01626 abundance and the HAMD scores in the MDD group. Finally, RF classification at the genus level can achieve an area under the receiver operating characteristic curve of 0.890.

CONCLUSIONS

The present findings enabled a better understanding of the changes in gut microbiota and the related Trp pathway in MDD. Alterations of the gut microbiota may have the potential as biomarkers for distinguishing MDD patients form HCs.

A study on attentional bias and response inhibition of facial expressions in manic patients: evidence from eye movement

Introduction: In recent years, evidence has accumulated to suggest that patients with bipolar disorder show altered processing of emotionally relevant information. However, only a few studies have examined manic patients' eye movements when processing facial expressions. Method: A free viewing task and anti-saccade task were used separately to investigate attentional bias and response inhibition while processing emotional stimuli. Data were drawn from matched samples of manic patients (n = 25) and healthy controls (n = 20). Results: The analyses of eye-movement data revealed that there was a significant difference between manic patients and healthy controls in the total duration of fixations but not in the orientation or duration of the first fixation. However, no significant differences between manic patients and healthy controls in response inhibition were detected. Conclusion: These results demonstrate that compared to healthy controls, manic patients show a deficiency in processing speed. The patients showed no attentional vigilance to happy or sad expressions but did showed avoidance of the sad expression and focused more on the happy expression in later emotion processing. There were no impairments of response inhibition detected in manic patients. Key points Abnormal processing of emotional information and having aberrant inner-experiences of emotion is a feature of bipolar disorders. Processing speed is slow in manic patients versus healthy controls. Manic patients focused lesser on sad expression than healthy controls, which suggesting an avoidance of sad expressions. The findings show that psychotherapies like CBT may be applicable to manic patients.

Similarly in depression, nuances of gut microbiota: Evidences from a shotgun metagenomics sequencing study on major depressive disorder versus bipolar disorder with current major depressive episode patients

BACKGROUND

To probe the differences of gut microbiota among major depressive disorder (MDD), bipolar disorder with current major depressive episode (BPD) and health participants.

METHODS

Thirty one MDD patients, thirty BPD patients, and thirty healthy controls (HCs) were recruited. All the faecal samples were analyzed by shotgun metagenomics sequencing. Except for routine analyses of alpha diversity, we specially designed a new indicator, the G_m coefficient, to evaluate the inequality of relative abundances of microbiota for each participant.

RESULTS

The G_m coefficients are significant decreased in both MDD and BPD groups. The relative abundances of increased phyla Firmicutes and Actinobacteria and decreased Bacteroidetes were significantly in the MDD and BPD groups. At genus level, four of top five enriched genera (Bacteroides, Clostridium, Bifidobacterium, Oscillibacter and Streptococcus) were found increased significantly in the MDD and BPD groups compared with HCs. The genera Escherichia and Klebsiella showed significant changes in abundances only between the BPD and HC groups. At the species level, compared with BPD patients, MDD patients had a higher abundance of Prevotellaceae including Prevotella denticola F0289, Prevotella intermedia 17, Prevotella ruminicola, and Prevotella intermedia. Furthermore, the abundance of Fusobacteriaceae, Escherichia blattae DSM 4481 and Klebsiella oxytoca were significantly increased, whereas the Bifidobacterium longum subsp. infantis ATCC 15697 = JCM 1222 was significantly reduced in BPD group compared with MDD group.

CONCLUSIONS

Our study suggested that gut microbiota may be involved in the pathogenesis of both MDD and BPD patients, and the nuances of bacteria may have the potentiality of being the biomarkers of MDD and BPD.

Designer germanium quantum dot phototransistor for near infrared optical detection and amplification

We demonstrated a unique CMOS approach for the production of a high-performance germanium (Ge) quantum dot (QD) metal-oxide-semiconductor phototransistor. In the darkness, low off-state leakage (Ioff ∼ 0.27 pA μm(-2)), a high on-off current ratio (Ion/Ioff ∼ 10(6)), and good switching behaviors (subthreshold swing of 175 mV/dec) were measured on our Ge-QD phototransistor at 300 K, indicating good hetero-interfacial quality of the Ge-on-Si. Illumination makes a significant enhancement in the drain current of Ge QD phototransistors when biased at both the on- and off-states, which is a great benefit from Ge QD-mediated photoconductive and photovoltaic effects. The measured photocurrent-to-dark-current ratio (Iphoto/Idark) and the photoresponsivities from the Ge QD phototransistor are as high as 4.1 × 10(6) and 1.7 A W(-1), respectively, under an incident power of 0.9 mW at 850 nm illumination. A superior external quantum efficiency of 240% and a very fast temporal response time of 1.4 ns suggest that our Ge QD MOS phototransistor offers great promise as optical switches and transducers for Si-based optical interconnects.

Size tunable Ge quantum dots for near-ultraviolet to near-infrared photosensing with high figures of merit

We report a unique approach for the inclusion of size-tunable (7-50 nm), spherical Ge quantum dots (QDs) into gate stacks of metal-oxide-semiconductor (MOS) diodes, through selective oxidation of SiGe layers over the buffer layer of Si3N4 deposited over the Si substrate. In this complementary MOS (CMOS)-compatible approach, we successfully realized high performance nm scale Ge-QD MOS photodetectors with high figures of merit of low dark current density (1.5 × 10(-3) mA cm(-2)), superior photo-current-to-dark current ratio (13 500), high photoresponsivity (2.2 A W(-1)), and fast response time (5 ns), which are ready for direct integration with Si CMOS electronic circuits. Most importantly, the detection wavelength of the Ge QDs is tunable from near infrared to near ultraviolet by reducing the QD size from 50 to 7 nm as well as the optimal photoresponsivity is tailored by the Ge QD size and the effective thickness of gate dielectrics.

3D time of flight MR angiography: acquisition with small field of view and low phase encodes

The aim of the study was to evaluate and compare the image quality of the 3D TOF MRA acquired with a small FOV and low phase encodes with those MR angiographic images acquired with standard pulse sequence parameters. Twenty patients who were referred to our institution for MR imaging of the brain and strictly satisfied the selection criteria were included in this study. Apart from the routine protocol for MR imaging of the brain, 3D TOF MRA of the circle of Willis with a small FOV and a standard FOV were performed. The image quality of all MRA was evaluated by two independent observers who were blind to the pulse sequence parameters. From the standard FOV MRA, 22.5, 12.5, and 5% of the patients were graded as mild, moderate, and severe stenosis of the internal carotid artery, respectively. On the contrary, no apparent stenosis was observed from the small FOV MRA with low phase encodes. Regarding the reduction in MR artifacts and acquisition time achieved with the small FOV 3D TOF MRA with low phase encodes, this might be a useful MR angiographic technique to be used in routine clinical practice.

Cystic left atrium myxoma--a rare case report

Myxoma is the most common primary tumor of heart. The typical picture of myxoma under echocardiography is a solid, dense echo mass and left atrium is the most common site to find it. The cystic form of myxoma is vary rare. We report a patient who received echocardiographic examination under impression of mitral valve stenosis. A multilobulated cystic mass which was like a hydatid cyst was found in the left atrium and atrioventricular flow was affected by this mass. After tumor resection, myxoma with internal hemorrhage was proved by pathology. No further recurrent myxoma was found during follow-up echocardiographic examination.

Seasonal variability of the QT dispersion in healthy subjects

We studied the seasonal variability of QT dispersion in 25 healthy subjects, aged 36 +/- 5 (25 to 46) years. Four seasonal 12-lead rest electrocardiograms (ECGs) recorded at a double amplitude were performed at 25 mm/s at intervals of roughly 3 months. To avoid possible confusion from the circadian rhythm of QT dispersion, subsequent ECGs were recorded within 30 minutes of the reference summer one. The QT dispersion was calculated as the difference between the longest and the shortest mean QT intervals. There was a seasonal variability in the QT dispersion (P =.001), with the largest QT dispersion occurring in winter (66 +/- 21 ms) and the smallest one in spring (48 +/- 18 ms). In conclusion, there exists a seasonal variability of QT dispersion in healthy subjects and such variability should be taken into consideration in comparison of the QT dispersion.

Atrioventricular block in Kearns-Sayre syndrome: a case report

The Kearns-Sayre (K-S) syndrome which includes the triad of progressive external ophthalmoplegia, pigment retinopathy, and disorder of cardiac conduction was first described in 1958. The mitochondria disorder is believed to be the cause of this syndrome. Involvement of the cardiac conduction system is the most importent prognostic factor in K-S syndrome. A 34-year-old male K-S syndrome patient, manifesting as ptosis and weakness of limbs since the age of 15 years, suffered from dizziness and weakness. Twelve-lead eletrocardiography (ECG) showed a 2:1 atrioventricular (AV) block with slow ventricular rate. Intermittent complete AV block, complete left bundle branch block and torsades de pointes were noted in Holter ECG. The electrophysiology study demonstrated prolonged HV interval (85 ms) on conduction beat and infra-His block on non-conduction beat. A VVIR mode of permanent pacemaker was implanted and the patient's condition was stable during this period of follow-up.

Serial changes of cardiac troponin-I in acute myoischemia induced by exercise treadmill test

Cardiac troponin-I (cTn-I) is a sensitive and specific marker for the diagnosis of acute myocardial infarction (AMI). However, elevation of serum cTn-I has been observed in some unstable angina patients who have a worse prognosis than those with normal serum cTn-I levels. It is unknown whether serum cTn-I can elevate in stable angina patients with acute ischemic burden. Therefore, the purpose of this study was to determine a serial change of cTn-I in patients with acute ischemia induced by a treadmill exercise test. Thirty-five patients suspected of having coronary artery disease and five healthy medical students were enrolled into this study. Every patient received a treadmill exercise test. Cardiac troponin-I was measured by fluorescent immunoassay before the treadmill test and at 5 minutes, 1 hour, 3 hours, and 6 hours after the treadmill test. Patients with cTn-I levels of less than 0.5 ng/ml were considered normal, and those with cTn-I levels of greater than 2.0 ng/ml was considered to have AMI. The exercise test was positive in 19 of the 35 patients and negative in 16 of the 35 patients and 5 medical students. Among the 19 patients with positive treadmill exercise test, the cTn-I concentrations were abnormally increased in 7/19 (37%) patients (mean: 1.1 +/- 0.4 ng/ml; range: 0.5 to 2.0 ng/ml). One of the 16 patients with negative treadmill test showed an increase of serum cTn-I. Normal cTn-I levels were found in the other 15 patients and the 5 medical students. In conclusion, serum cTn-I levels were found to increase to some extent in one third of stable angina patients who have an acute ischemic episode induced by treadmill exercise test.

The effect of fluvastatin on fibrinolytic factors in patients with hypercholesterolemia

Several studies have shown cardiovascular benefit in treating hypercholesterolemia with HMG-CoA reductase inhibitor. However, in addition to the lowering of cholesterol, the beneficial effects of this inhibitor reflect other pharmacological activities. Whether these beneficial effects are partly mediated by changes in fibrinolytic factors remains to be proven, since clinical studies on the effects of HMG-CoA reductase inhibitors on fibrinolytic factors have not yielded consistent results. The purpose of this study was to evaluate the effects of fluvastatin on fibrinolytic factors in hypercholesterolemic patients. After 6 weeks on a low-fat, low-cholesterol diet, 23 outpatients known to have primary hypercholesterolemia with low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl with at least 2 risk factors or fasting LDL-C > or = 160 mg/dl were selected for the study. Venous blood samples were collected at baseline and at 8 weeks after fluvastatin therapy (40 mg/day) to measure of tissue plasminogen activator (t-PA), plasminogen activators inhibitor-1 (PAI-1), fibrinogen, D-dimer and lipid profile. After 8 weeks of therapy, fluvastatin reduced serum cholesterol by 11% (261.9 mg/dl vs 233.2 mg/dl, P < 0.01) and LDL-C by 22% (191.9 mg/dl vs 149.3 mg/dl, P < 0.01). D-dimer was significantly decreased (0.38 ng/L vs 0.28 ng/L, P = 0.02) and tPA, PAI-1 and fibrinogen tended to decrease after therapy. Fluvastatin therapy improved fibrinolytic profile; the result of this study may in part explain the benefit of HMG-CoA reductase inhibitor on cardiovascular system other than lipid lowering.

Impression cytology of pterygium

The purpose of this study was to study the morphology and cytokeratin expression in the epithelia of pterygia. Impression cytology and immunohistochemical staining with antikeratin antibodies were performed in 32 eyes of 16 patients with pterygia. TUNEL stain and electron microscopy were also performed in surgical specimens ofpterygium. Squamous metaplasia-like epithelial cells were found in all specimens of impression cytology, especially in the head part. These specimens had positive immunostaining by antipancytokeratin antibodies, but not by anti-K12 AK2 mAb. Goblet cells were found around the area of these abnormal epithelial cells. TUNEL-positive cells were found in the epithelia of the pterygial head, but not in the body of pterygia and normal conjunctiva. The expressional patterns of keratin by these epithelial cells ofpterygia are consistent with the notion that they are derived from conjunctival epithelium and mimic the process of squamous metaplasia.

Partial anomalous pulmonary venous connection draining into superior vena cava--two cases reports

Anomalous pulmonary venous connection is a relatively common associated anomaly in patients with atrial septal defect (ASD), particularly among those with the sinus venosus type. The incidence of partial anomalous pulmonary venous connection (PAPVC) is higher than 0.7% in the general population and 10% in patients with ASD. In this study, we present two cases with initial impression of ASD, the sinus venosus type in one and the secundum type in the other. The one with the sinus venosus type was found to have a PAPVC that drained into SVC, and the other was suspected of having the same problem because an abnormal shunt was found during cardiac catheterization. This speculation could not be proved, however, due to transesophageal echocardiogram failure. Because we feared the possibility of cardiac defects other than ASD, we performed a minimally invasive operation using a small midline incision instead of the submammary incision and did a full median sternotomy on the patient to look for other complicating coexistent cardiac defects. This patient and the former one were both proven intraoperatively to have a PAPVC that drained into SVC with sinus venosus ASD. The operation to correct an ASD is a rudimentary procedure, and it often becomes a common type of minimally invasive operation among young cardiac surgeons with limited experience. A submammary incision under the impression of simple ASD may meet with certain complications. Therefore, after our experience with the latter case, we do the minimally invasive operation using a small midline incision, which can be easily extended if need be.

A unique xanthine derivative KMCP-98 with activation of adenosine receptor subtypes

KMCP-98 is a newly synthesized adenosine receptor agonist by alkylation at the 7-position of the xanthines nucleus. We first investigated the pharmacological activities of KMCP-98 under in vivo and in vitro conditions. Acute intravenous injection of KMCP-98 (1.0, 2.0 and 3.0 mg/kg) produced a temporary fall in blood pressure and heart rate, followed by a sustained fall in heart rate in pentobarbital-anesthetized Wistar rats. The hypotensive and bradycardiac responses were inhibited by pretreatment with an A(1) adenosine receptor antagonist 8-phenyltheophylline (8-PT, 0.5 mg/kg). Both KMCP-98 and adenosine (0.3-100 microM) produced negative inotropic activity in isolated guinea pig left atria. The negative inotropic activity of KMCP-98 was significantly blocked by pretreatment with A(1) receptor antagonists 8-PT (10 microM) and xanthine amine congener (XAC, 10 microM), a nonselective adenosine antagonist theophylline (10 microM), a K(+) channel blocker tetraethylammonium (TEA, 10 mM) and a K(ATP) channel blocker glibenclamide (1 microM). KMCP-98 (0.03-30 microM) produced concentration-dependent relaxations in carbachol (1 microM) precontracted guinea pig tracheal smooth muscle. The trachea relaxant response of KMCP-98 was markedly inhibited by A(2), A(2a) and A(2b) adenosine receptor antagonists 3,7-dimethyl-1-propargylxanthine (DMPX, 10 microM), 8-(3-chlorostyryl)caffeine (CSC, 10 microM) and alloxazine (10 microM), respectively, the nitric oxide synthase (NOS) inhibitor L-NAME (100 microM) and also by TEA and glibenclamide. In addition, KMCP-98 (0.03-30 microM) elicited relaxant response in norepinephrine (3 microM) precontracted rat thoracic aorta in a concentration-dependent manner. The thoracic aorta relaxant response of KMCP-98 was also significantly inhibited by DMPX, CSC, alloxazine, L-NAME, TEA and glibenclamide. Furthermore, the binding characteristics of KMCP-98, adenosine and 5'-N-ethylcarboxaminoadenosine (NECA) were evaluated in [(3)H]DPCPX and [(3)H]CGS 21680 binding to rat cortex and striatum, respectively. The K(i) values of KMCP-98 for predominate A(1) and A(2) adenosine receptor sites were 3908+/-952 and 158+/-10 nM, respectively. In conclusion, KMCP-98 was found to be a xanthine-based adenosine receptor agonist associated cardiac depression, tracheal and aortic smooth muscle relaxations.

Role of left ventricular activation sequence in the genesis of isovolumic relaxation flow in the Wolff-Parkinson-White syndrome

In patients with left Kent bundle, the initial phase of isovolumic relaxation flow was directed basally at pre-excited beats, but apically at nonpreexcited beats or after successful ablation of the Kent bundle. This suggests an important role of the left ventricular activation sequence in the direction of isovolumic relaxation flow.

Differential effects of adenosine on antegrade and retrograde fast pathway conduction in atrioventricular nodal reentry

Although adenosine depresses antegrade atrioventricular (AV) nodal conduction, the effects of adenosine on antegrade and retrograde fast pathway conduction in AV nodal reentry have not been determined. In 17 patients (five men, 12 women, mean age 49 +/- 12 years) with common slow-fast AV nodal reentrant tachycardia, the antegrade slow pathway conduction was selectively and completely ablated by radiofrequency catheter ablation while the antegrade and retrograde fast pathway conduction remained intact. During high right atrial pacing at a mean pacing cycle length of 474 +/- 36 msec, adenosine was rapidly injected intravenously at an initial dose of 0.5 mg followed by stepwise increases of 0.5 mg or 1.0 mg given at 5-minute intervals until second-degree AV block developed. During right ventricular apical pacing at the same pacing cycle lengths (mean 474 +/- 36 msec) as those in the study of antegrade conduction, intravenous injection of incremental doses of adenosine was repeated until ventriculoatrial (VA) block occurred. The adenosine-induced prolongation of VA conduction was also determined in the presence of verapamil (loading dose 0.15 mg/kg, maintenance dose 0.005 mg/kg/min) in seven of 17 patients. The dose of adenosine required to produce AV block, the increase in the atrio-His interval by 50% and the maximal response were 3.4 +/- 1.4 mg, 1.8 +/- 0.6 mg, and 58% +/- 5%, respectively. On the other hand, the dose of adenosine required to produce VA block, the increase in the VA interval by 50%, and the maximal response were 8.2 +/- 2.9 mg, 3.4 +/- 0.6 mg, and 20% +/- 5%, respectively, in the control and 3.7 +/- 0.5 mg, 3.5 +/- 0.7 mg, and 23% +/- 5%, respectively, in the presence of verapamil. In conclusion, adenosine has a differential potency to depress AV and VA conduction in patients with AV nodal reentry, with greater potency for slowing antegrade fast than retrograde fast pathway conduction. Verapamil had an additive effect to adenosine on slowing retrograde VA conduction, which further supports the evidence that the retrograde fast pathway in part involves an AV nodal-like structure.

Effects of verapamil, propranolol, and procainamide on adenosine-induced negative dromotropism in human beings

Adenosine, verapamil, propranolol, and procainamide are widely used antiarrhythmic drugs. The interactions among them are still not known in human beings. Adenosine-induced negative dromotropic effects were assessed by rapid bolus injection of adenosine during constant high right atrial pacing in each patient. The initial dose of adenosine was 0.5 mg and was followed by a stepwise increment of 0.5 mg until atrioventricular (AV) nodal block occurred. The negative dromotropic actions of adenosine were examined in the control state and in the following three protocols in three groups of patients: (1) In 12 patients (group 1), intravenous verapamil, 0.15 mg/kg, was given; (2) In 12 patients (group 2), intravenous propranolol, 0.1 mg/kg, was given; and (3) in 10 patients (group 3), intravenous procainamide, 15 mg/kg, was given. The dose-response curves of adenosine on AV nodal conduction were almost identical in the control state and after verapamil, propranolol, or procainamide injection. However, verapamil, in contrast to propranolol, significantly reduced the dose of adenosine required to produce AV nodal block, from 4.4 +/- 0.7 mg to 2.7 +/- 0.3 mg (p < 0.01). Of note, procainamide exerted no significant effects on adenosine-induced negative dromotropism on AV nodal conduction or AV nodal block. In conclusion, the negative dromotropic effects of adenosine are preserved and independent even in the presence of verapamil, propranolol, or procainamide. Both verapamil and propranolol can exhibit additive effects with adenosine in prolonging AV nodal conduction time; however, only verapamil can reduce the dose of adenosine required to produce AV nodal block. This finding indicates that the dose of adenosine may be reduced for patients who have already been treated with verapamil.

Surgical correction of giant patent ductus arteriosus

In reviewing the literature, there was only one report having the ductus over 30 mm in width. Recently, we utilized cardiopulmonary bypass, hypothermia, and low flow through a transpulmonary approach to close 2 cases of giant patent ductus arteriosus. Both cases complicated with systemic pulmonary hypertension. Its outside diameters were 31 mm and 36 mm respectively based on the measurement from magnetic resonance imaging. To our knowledge, its seem the biggest ductus in comparison to previous reports. Both cases survived the operation and doing well for a follow-up time of 5 years and 4 years 10 months respectively.

Spectrum of electrophysiologic and electropharmacologic characteristics of verapamil-sensitive ventricular tachycardia in patients without structural heart disease

Verapamil-sensitive ventricular tachycardia (VT) is a well-recognized clinical entity that some authorities believe may result from triggered activity. Despite its uniform response to verapamil, however, there is evidence that this uncommon form of VT may not be as homogeneous as first believed. Standard intracardiac electrophysiologic techniques were used to study verapamil-sensitive VT in 32 patients (aged 38 years +/- 20 years) without evidence of structural heart disease. More than half of these patients (69%) exhibited VT with a right bundle branch block-type QRS pattern, with the remainder (31%) displaying VT with a left bundle branch block pattern. In 31% of the patients the VT could be induced by fixed-cycle length atrial pacing, whereas in 59% of patients fixed-cycle length ventricular pacing was necessary. A critical range of cycle lengths for VT induction was required in 66% of the patients. Ventricular tachycardia was initiated with single atrial premature extrastimuli in 16% of patients, single ventricular extrastimuli in 50% of patients, and double ventricular premature extrastimuli in 9% of patients. Ventricular tachycardia displaying cycle-length alternans was observed in 28% of patients. In only 19% of patients was it possible to entrain VT during pacing from the right ventricular apex. Isoproterenol infusion was required for tachycardia induction in 50% of patients, 44% of whom had VT with a left bundle branch block QRS pattern, with the remaining 56% exhibiting VT with a right bundle branch block pattern. Beta-adrenergic blockers suppressed 53% of verapamil-sensitive VT in patients tested, whereas adenosine terminated VT in 50% of patients, with 81% of these patients exhibiting either a left bundle branch block QRS pattern or isoproterenol dependence. Ventricular tachycardia exhibiting a left bundle branch block pattern was more likely to be isoproterenol dependent (p <0.05) and adenosine sensitive (p <0.001). However, verapamil-sensitive, catecholamine-dependent VT was no more likely to be adenosine sensitive than the catecholamine-independent form of the arrhythmia (p >0.5). Verapamil-sensitive VT exhibits properties expected of both a reentrant and triggered arrhythmia, and it is inconsistently dependent on both exogenous catecholamines for induction and intravenous adenosine for termination. Verapamil-sensitive VT encompasses a heterogeneous group of tachycardias that may result from multiple cellular electrophysiologic mechanisms.

Electrophysiological manifestations of the excitable gap of slow-fast AV nodal reentrant tachycardia demonstrated by single extrastimulation

BACKGROUND

Although AV nodal reentrant tachycardia (AVNRT) is a well-known rhythm disorder, its anatomic substrate and electrophysiological mechanism remain to be defined. Previously, the description of the excitable gap (EG) of AVNRT was based on electrical stimulation performed from sites remote from the reentrant circuit. In the present study, we characterized the EG of AVNRT by atrial extrastimulation close to the putative reentrant circuit in the AV junction.

METHODS AND RESULTS

In 16 patients (3 men, 13 women; mean age, 45 +/- 13 years) with inducible slow-fast AVNRT (mean cycle length, 353 +/- 52 ms), single extrastimuli with a 10-ms decrement in the premature coupling interval were delivered from the anterosuperior interatrial septum (fast pathway area) and the posteroinferior interatrial septum (slow pathway area) from late diastole until atrial refractoriness. An EG was considered present when resetting or termination of AVNRT was induced by single atrial extrastimulation. The study showed that the duration of the EG of AVNRT was wide, measuring 121 +/- 56 and 123 +/- 47 ms and occupying 33 +/- 11% and 34 +/- 9% of the tachycardia cycle length during single extrastimulation from the slow pathway area and the fast pathway area, respectively. The resetting pattern most commonly manifested as the sum of the coupling interval and the return cycle being less than a fully compensatory pause (two times the basic tachycardia cycle length). However, patterns equal to and greater than a fully compensatory pause were also observed. Of note, in 2 of the 16 patients, atrial extrastimulation from either the fast or slow pathway area also affected the preceding tachycardia cycle length (HH interval), indicating alteration of the anterograde input. In all patients, the curve derived from plotting the coupling interval of extrastimuli against the return cycle during resetting exhibited an "increasing" pattern. The mode of tachycardia termination usually occurred when the premature atrial impulse was orthodromically blocked in the anterograde slow pathway.

CONCLUSIONS

The EG of slow-fast AVNRT is relatively wide, as demonstrated by single atrial extrastimulation from the interatrial septum near the AV junction. Overall, the electrophysiological manifestations of the EG of AVNRT are very similar to those described in AV reciprocating tachycardia incorporating an accessory connection. These findings lend further support to the notion that, in humans, AVNRT involves a reentrant mechanism with a wide excitable gap.

Sick sinus syndrome with normal atropine response--a case report

A 76-year-old woman was admitted due to recurrent syncope. Sinus bradycardia and intermittent sinus pauses (up to 2.24 sec) were documented by 24 hour Holter electrocardiogram. Although intravenous atropine can increase the sinus rate up to 100 bpm, electrophysiologic study showed marked prolongation of sinus node recovery time both at the control state and after autonomic blockades. Sick sinus syndrome was diagnosed, even with a normal atropine test, and a permanent pacemaker resulted in resolution of the syncope.

Surgical correction of sinus venosus atrial septal defect associated with partial anomalous pulmonary venous connection to high superior vena cava--case report

A 63-year-old woman complained of general malaise and insomnia initially. Atrial septal defect was diagnosed by transthoracic echocardiography thereafter. She had not received complete cardiac studies until progressive dyspnea was noted half a year later. After a series of examinations, sinus venosus type atrial septal defect (ASD) associated with partial anomalous pulmonary venous connection to high superior vena cava (SVC) and persistent left SVC was documented. Surgical correction was performed later. The postoperative course was smooth and her condition improved gradually at 10-month follow-up.

Rate-dependent properties of adenosine-induced negative dromotropism in humans

BACKGROUND

The antiarrhythmic effects of sodium channel and calcium channel blockers are known to be rate dependent. Little is known about the rate-dependent effect of adenosine on human atrioventricular (AV) nodal conduction. The purpose of this study was to determine whether the negative dromotropic effect of adenosine is dependent on heart rate.

METHODS AND RESULTS

Atrial pacing at 20-millisecond increments decreasing stepwise was performed, and the curves that relate the AH interval to the atrial pacing cycle length were analyzed. The change in AV nodal function was evaluated in three protocols: (1) In 8 group 1A and 6 group 1B patients, an intravenous infusion of adenosine at a dose of 140 and 320 micrograms.kg-1.min-1 was given, respectively; (2) a bolus injection of a fixed dose of adenosine was given to 12 group 2A patients without and 6 group 2B patients with propranolol (0.1 mg/kg) treatment; and (3) in 12 group 3 patients, the AV nodal function was evaluated after intravenous propranolol (0.05 mg/kg) and after subsequent intravenous aminophylline (loading dose, 5 mg/kg; maintenance dose, 0.9 mg.kg-1.h-1). No significant depression of AV nodal function could be demonstrated during intravenous infusion of adenosine. The bolus injection of adenosine could prolong the AH interval, which was dependent on heart rate and more significant at a shorter pacing cycle length. Intravenous propranolol significantly depressed the AV nodal conduction and shifted the curves of the AH interval versus the pacing cycle length to the right. Subsequent intravenous aminophylline shortened the AV nodal conduction time, however, in a rate-independent manner.

CONCLUSIONS

The negative dromotropic effects induced by intravenous bolus injection of adenosine became more pronounced at fast atrial pacing rates. These results indicate that adenosine causes rate-dependent prolongation of AV nodal conduction in humans.

Efficacy and safety of radiofrequency catheter ablation for paroxysmal supraventricular tachycardias

From January 1992 to June 1993, 100 consecutive patients with clinically documented paroxysmal supraventricular tachycardias underwent radiofrequency catheter ablation. Group 1 consisted of 46 patients (male:female = 9:37, age: 46 +/- 13 years) with slow-fast atrioventricular nodal reentrant tachycardia. Radiofrequency current was aimed at the slow pathway area which was identified by both anatomical and electrophysiological methods. A mean application of 8 +/- 9 was delivered at a mean power of 22 +/- 4 watts with a mean duration of 21 +/- 3 seconds. Selective ablation of slow pathway conduction was achieved in 28 patients and modification of slow pathway conduction in 12 patients. Antegrade fast pathway conduction was ablated in 3 patients, and retrograde fast pathway conduction in 1. Mean peak CPK was 156 +/- 117 IU/L after ablation. Neither AV block nor clinical recurrence was found during 9.7 +/- 5.1 months follow up. Group 2 consisted of 54 patients with accessory pathway (AP) mediated atrioventricular reciprocating tachycardia. For 35 patients (M:F = 21:14, age: 40 +/- 12 years) who had left-sided accessory pathway, catheter ablation was approached by the retrograde trans-aortic technique in 33 patients and by the transseptal left atrial approach through patent foramen ovale in 2 patients. The mean energy delivered was 28 +/- 5 watts for a duration of 27 +/- 12 sec and 9 +/- 8 applications. The accessory pathway conduction was successfully ablated in 30 patients (86%). Mean peak CPK was 392 +/- 534 IU/L. Cardiac tamponade occurred in 1 patient and transient cerebral ischemia in another, but without mortality. No clinical recurrence was found during 9 +/- 4 months follow-up. Nineteen patients (M:F = 7:12, age: 36 +/- 11 years) had right-sided AP. The mean energy required for successful ablation was 30 +/- 4 watts for a duration of 35 +/- 15 sec and 12 +/- 9 applications. Mean peak CPK was 147 +/- 70 IU/L. Clinical recurrence occurred in 3 patients (15.8%), 1 of them had subsequent successive ablation. The overall immediate procedure success rate for right-sided AP was 65%. In conclusion, radiofrequency catheter ablation is a safe and effective treatment modality for patients with paroxysmal supraventricular tachycardias.

The circadian variations of blood pressure and heart rate in patients with mitral valve prolapse

It is well known that both normal subjects and hypertensives manifest a distinct nocturnal fall of arterial blood pressure and heart rate. But till now there has been no report about the diurnal change of blood pressure and heart rate in MVP patients. In this report we studied the circadian variations of blood pressure and heart rate in 18 symptomatic MVP patients (mean age 32 +/- 10 years) and compared them with those in 18 age- and sex-matched normal control subjects (mean age 35 +/- 9 years). The MVP group presented a statistically significant blunting of the nocturnal fall in systolic blood pressure (4.2 +/- 3.6% vs 9.7 +/- 3.7%, p = 0.0002). No obvious difference in the nocturnal fall in heart rate was noted between both groups (20.2 +/- 6.0% vs 18.8 +/- 5.6%, p = 0.4290). In conclusion, the circadian variation of blood pressure was blunted in patients with mitral valve prolapse. The mechanism is uncertain and further studies are necessary to clarify it.

Cardiac amyloidosis--a case report

A 52-year-old male patient presented with resistant congestive heart failure. Echocardiographic findings revealed increased right ventricular (RV) wall thickness in conjunction with concentric left ventricular (LV) hypertrophy, LV systolic dysfunction and a granular sparking myocardial appearance. Doppler assessment showed a restrictive LV and RV diastolic filling pattern. These echocardiographic features combined with low voltage of the electrocardiogram is highly suggestive of cardiac amyloidosis. The diagnosis was confirmed by cardiac catheterization and endomyocardial biopsy.

Effect of ionic contrast medium on plasma atrial natriuretic peptide

To evaluate the effect of ionic contrast medium on plasma atrial natriuretic peptide (ANP) and its contributing factors, we measured plasma ANP, serum osmolality, pulmonary capillary wedge pressure (PCWP), femoral artery systolic pressure (FASP), and heart rate before and after left ventriculography with Rayvist in 13 patients suspected of coronary artery disease. The control values of plasma ANP, serum osmolality, and PCWP were 20.3 +/- 5.1 pg/ml, 293.5 +/- 1.5 mosm/kg, 6.6 +/- 0.8 mm Hg, respectively. Rayvist produced a significant increase in plasma ANP, serum osmolality, and PCWP at 1 minute (26.0 +/- 6.3 pg/ml, p < 0.05; 300.7 +/- 1.9 mosm/Kg, p < 0.001; 10.7 +/- 1.3 mm Hg, p < 0.001) and 5 minutes (27.3 +/- 6.3 pg/ml, p < 0.01; 296.8 +/- 1.9 mosm/Kg, p < 0.001; 10.4 +/- 1.7 mm Hg, p < 0.01) post left ventriculography. The FASP decreased significantly at 1 minute, followed by an insignificant increase at 5 minutes. The heart rate increased significantly at 1 minute but no significant change was noted at 5 minutes. We conclude that plasma ANP increases significantly after left ventriculography with Rayvist and its response may be related to left ventricular filling pressure and serum osmolality, but not to FASP or heart rate.

Comparison of the electrophysiologic effects of oral sustained-release and intravenous verapamil in patients with paroxysmal supraventricular tachycardia

The electrophysiologic effects of intravenous verapamil (0.15 mg/kg) and oral sustained-release verapamil (verapamil-SR) (240 mg once daily for 7 days) were studied in 17 patients with paroxysmal supraventricular tachycardia (SVT). Ten patients had atrioventricular (AV) nodal reentrant tachycardia and 7 had AV reciprocating tachycardia involving an accessory AV pathway. Both preparations significantly prolonged anterograde effective refractory period of the AV node and depressed the retrograde AV nodal conduction system. The sinus cycle length, and atrial and ventricular effective refractory periods were prolonged after oral verapamil-SR. Furthermore, oral verapamil-SR depressed retrograde accessory pathway conduction which was not interfered with by intravenous verapamil. Intravenous verapamil and oral verapamil-SR prevented induction of sustained SVT in 12 of 17 (71%) and 10 of 17 (59%) patients, respectively. Follow-up study with oral verapamil-SR 240 mg once daily in 15 patients for 19 +/- 6 months revealed that among the 8 patients without induction of sustained SVT, 7 have been free of symptomatic arrhythmia; only 1 patient had occasional SVT attacks. For the 7 patients with induction of sustained SVT, 3 patients failed to respond to oral verapamil-SR, 1 patient became symptom free, and the remaining 3 patients had less frequent SVT attacks. Thus, immediate intravenous verapamil testing predicts the electrophysiologic results of oral verapamil-SR therapy, and oral verapamil-SR once daily may be used for long-term prophylaxis of SVT with better patient compliance.

Negative dromotropism of adenosine under beta-adrenergic stimulation with isoproterenol

Adenosine depresses atrioventricular (AV) nodal function by binding to specific A1 receptors which activate the acetylcholine, adenosine-regulated potassium current. In addition, adenosine can act to antagonize the effects of beta-adrenergic stimulation on AV nodal function. To assess the negative dromotropic effects of adenosine under beta-adrenergic stimulation, 15 patients were studied during clinical electrophysiologic study. During high right atrial pacing at a cycle length of 400 to 600 ms, adenosine was injected intravenously at an initial dose of 0.5 mg followed by a stepwise increment of 0.5 or 1.0 mg given at 5-minute intervals until a maximal dose of 12 mg was achieved or AV block developed. Intravenous isoproterenol (1 to 3 micrograms/min) was then infused to accelerate sinus rate by 20 to 30% during which intravenous injection of incremental doses of adenosine as described was repeated. The AV nodal conduction time (AH interval) was measured at each dose of adenosine. Dose-response curves of AV nodal conduction time (expressed as percent increase in AH interval) were studied during the control state and during isoproterenol infusion. The dose of adenosine required to produce AV nodal Wenckebach block, the increase in the AH interval by 50% (ED50) and the maximal response (Emax) were 3.4 +/- 0.9 mg, 1.8 +/- 0.9 mg and 60 +/- 4%, respectively, in the control state, and 3.7 +/- 0.8 mg, 2.0 +/- 0.7 mg and 56 +/- 4%, respectively, during isoproterenol infusion. No significant changes in ED50, Emax and the dose of adenosine yielding AV nodal Wenckebach block could be demonstrated between the control state and during isoproterenol infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Is sick sinus syndrome an adenosine-mediated disease? Effects of intravenous aminophylline on sick sinus node function after pharmacologic autonomic blockade

To assess the effects of intravenous aminophylline on the sinus node, 12 patients with clinical and Holter monitor-documented sick sinus syndrome were studied (1) during the control state, (2) after pharmacologic autonomic blockade and (3) 5 min after intravenous administration of aminophylline. The effects of aminophylline on sinus node function were compared with those after pharmacologic autonomic blockade. No significant improvement of sinus node function was found after intravenous aminophylline administration with a mean sinus cycle length and a mean maximum CSRT of 968 +/- 218 and 1832 +/- 1036 ms, respectively. The mean serum theophylline level was 10.9 +/- 1.7 micrograms/ml. Since aminophylline is an adenosine receptor antagonist, these findings suggest that intrinsic adenosine may not play an important role in pathogenesis in patients with chronic and advanced sick sinus syndrome.

Role of intravenous isoproterenol in the electrophysiologic induction of atrioventricular node reentrant tachycardia in patients with dual atrioventricular node pathways

To assess the role of intravenous isoproterenol for the facilitation of electrophysiologic induction of atrioventricular (AV) node reentrant tachycardia, 20 patients with dual AV node pathways who lacked inducible AV node reentrant tachycardia at control study had a constant isoproterenol infusion administered and underwent repeat study. Six (30%) of 20 patients (group I) had inducible AV node reentrant tachycardia during isoproterenol infusion whereas the other 14 (70%) patients (group II) did not. Paroxysmal supraventricular tachycardia was clinically documented in all 6 group I patients compared to 3 (21%) of 14 group II patients (p = 0.002). The sensitivity and specificity of isoproterenol-facilitated induction of AV node reentrant tachycardia were 67 and 100%, respectively. The isoproterenol-facilitated induction of sustained AV node reentry was mediated by resolution of the weak link in anterograde slow pathway in 2 (33%) patients, in retrograde fast pathway in 3 (50%) and in both anterograde slow and retrograde fast pathways in 1 (17%) patient. Four group I patients were given intravenous propranolol, 0.2 mg/kg body weight, and had complete suppression of isoproterenol-facilitated induction of AV node reentry. Thus, intravenous isoproterenol is a rather sensitive and highly specific adjunct to electrophysiologic induction of AV node reentrant tachycardia in patients with dual AV node pathways but without inducible sustained AV node reentry.

Electrophysiologic manifestations of the excitable gap of orthodromic atrioventricular reciprocating tachycardia demonstrated by single extrastimulation

To assess the electrophysiologic characteristics of the excitable gap, 12 patients with orthodromic atrioventricular (AV) reciprocating tachycardia were studied. During tachycardia, 8 patients used a left-sided and 4 patients a right-sided anomalous bypass tract for retrograde conduction. QRS complex-synchronized single extrastimuli were delivered from high right atrium, right ventricular apex and coronary sinus, respectively, scanning the whole cycle length of tachycardia. An excitable gap was determined to be present if tachycardia resetting or tachycardia termination occurred. The duration of the excitable gap varied among different pacing sites and occupied 0 to 48% (mean 17 +/- 16) of basic tachycardia cycle length (240 to 480 ms, mean 327 +/- 70). Three patterns of tachycardia resetting were observed: the sum of coupling interval and return cycle being (1) less than a fully compensatory pause in 12 of 12 patients, (2) more than a fully compensatory pause in 5 of 12 patients and (3) equal to a fully compensatory pause in 2 of 12 patients, depending on extent of AV nodal conduction delay exhibited in return cycle. Tachycardia termination was possible when extrastimuli were delivered from right ventricular apex and coronary sinus but not from high right atrium, and only when basic tachycardia cycle length was greater than or equal to 290 ms in 7 of 12 patients. Tachycardia termination was accounted for by development of orthodromic conduction block in AV node in 7 of 7 patients and in bypass tract in 2 of 7 patients. Therefore, site of extra-stimulation and basic tachycardia cycle length affect electrophysiologic manifestations of excitable gap. Further, functional properties of the AV node influence patterns of tachycardia resetting and are primarily responsible for tachycardia termination during programmed single extrastimulation.

Supraventricular tachyarrhythmias. Mechanisms, types, and management

Advances in the area of clinical electrophysiology have allowed definition of the mechanisms of most forms of supraventricular tachyarrhythmias. Reentry, automaticity, and triggered activity are the three basic mechanisms. Treatment of the arrhythmias is based on frequency and hemodynamic severity. After accurate diagnosis, empirical therapy with currently available medications usually controls symptomatic supraventricular tachyarrhythmias. Nonpharmacologic therapy with permanent antitachycardia pacemakers, percutaneous catheter ablation, or surgery is indicated for selected patients with medically recalcitrant supraventricular tachyarrhythmia.