Remodeling of myocardial energy and metabolic homeostasis in a sheep model of persistent atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common progressive cardiac arrhythmia and is often associated with rapid contraction in both atria and ventricles. The role of atrial energy and metabolic homeostasis in AF progression is under-investigated. OBJECTIVES: To determine the remodeling of energy metabolism during persistent AF and the effect of eplerenone (EPL), an aldosterone inhibitor, on metabolic homeostasis. METHODS: A nonsustained atrial pacing sheep model was developed to simulate the progression of AF from paroxysmal to persistent. Metabolomic and proteomic analyses at termination of the experiment were used to analyze atrial tissues obtained from sheep in sham, sugar pill (SP) and EPL-treated groups. RESULTS: Proteomic analysis indicated that compared to the sham group, in SP group, fatty acid (FA) synthesis, FA oxidation, tricarboxylic acid (TCA) cycle processes and amino acids (AAs) transport and metabolism were reduced, while glycolytic processes were increased. In metabolomic analysis, the levels of intermediate metabolites of the glycolytic pathways, including 2-phosphoglyceric acid (2 PG), 1,3-bisphosphoglyceric acid (1,3 PG), and pyruvate, HBP (uridine diphosphate-N-acetylglucosamine, UDP-GlcNAc), TCA (citrate) and AAs were greater while the levels of the majority of lipid classes, including phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylglycerol (PG), glycerophosphoglycerophosphates (PGP), glycerophosphoinositols (PI) and glycerophosphoserines (PS), were decreased in the atria of SP group than in those of sham group. EPL-pretreatment decreased the expression of glut4 and increased the content of acylcarnitines and lipids, such as lyso phospholipids, phospholipids and neutral lipids. CONCLUSION: In the metabolic remodeling during AF, glucose and lipid metabolism were up- and down-regulated, respectively, to sustain TCA cycle anaplerosis. EPL partialy reversed the metabolic shifting.

T Wave Safety Margin during the Process of ICD Implantation As a Novel Predictor of T Wave Oversensing.

Introduction: T wave oversensing (TWOS) is a major drawback of implantable cardioverter defibrillator (ICD) and data on predictors of TWOS in ICD is limited. We aimed to calculate a novel index of T wave safety margin (TWSM) and assess its potential for evaluating TWOS during the procedure of ICD implantation. Methods and Results: Thirty-two consecutive patients with ICD implantation were enrolled. During each procedure of ICD implantation, different ICD generators were connected to implanted sensing lead through active-fixation leads and bridging cables. R and T wave amplitudes were measured on ICD printouts according to the gain. The ICDs were programed to the most sensitive settings to reveal possible TWOS. A novel index TWSM was calculated according to the corresponding sensing algorithm of ICD. There was discrepancy of R wave amplitudes measured by different ICDs (P < 0.01). In Fortify and Teligen ICDs, T wave amplitudes showed no difference (P > 0.05) and TWSMs were sufficiently high (post sensing: 13.0 ± 7.6 and 28.3 ± 16.5, respectively, post pacing: 5.0 ± 2.2 and 4.6 ± 0.9, respectively). In nine patients with 10 TWOS episodes detected during the procedure of ICD implantation, generators with the highest TWSM were chosen. Only one TWOS episode during pacing was recorded during the 25 ± 7 mo follow-up period. Conclusions: We first propose the index of TWSM during ICD implantation as a potentially efficient predictor for TWOS. Evaluation of TWSM might help to reduce TWOS episodes in patients with high risk of TWOS. Prospective studies are warranted to validate this index and its potential to reduce TWOS episodes.

Genetic identification and risk factor analysis of asymptomatic bacterial colonization on cardiovascular implantable electronic devices.

Asymptomatic bacterial colonization of cardiovascular implantable electronic devices (CIEDs) is widespread and increases the risk of clinical CIED infection. The aim of the study was to evaluate the incidence of bacterial colonization of generator pockets in patients without signs of infection and to analyze the relationship with clinical infection and risk factors. From June 2011 to December 2012, 78 patients underwent CIED replacement or upgrade. Exclusion criteria included a clinical diagnosis of CIED infection, bacteremia, or infective endocarditis. All patients were examined for evidence of bacterial 16S rDNA on the device and in the surrounding tissues. Infection cases were recorded during follow-up. The bacterial-positive rate was 38.5% (30 cases); the coagulase-negative Staphylococcus detection rate was the highest (9 cases, 11.5%). Positive bacterial DNA results were obtained from pocket tissue in 23.1% of patients (18 cases), and bacterial DNA was detected on the device in 29.5% of patients (23 cases). During follow-up (median 24.6 months), two patients (6.7%, 2/30) became symptomatic with the same species of microorganism, S. aureus and S. epidermidis. Multivariable logistic regression analysis found that the history of bacterial infection, use of antibiotics, application of antiplatelet drugs, replacement frequency, and renal insufficiency were independent risk factors for asymptomatic bacterial colonization.

Detection of sleep apnea-hypopnea syndrome with ECG derived respiration in Chinese population.

Evaluation of sleep apnea-hypopnea syndrome (SAHS) is mainly based on the polysomnogram (PSG), which is considered as the golden diagnostic criteria. As a novel noninvasive and low cost alternative method to detect SAHS patients, the diagnostic power of ECG-derived respiration (EDR) hasn't been well determined. In light of this, we tested whether EDR can be utilized as a feasible tool to diagnose SAHS in Chinese patients. Overnight sleep investigation was performed in 120 subjects using polysomnogram (PSG) and 24-hour ambulatory electrocardiogram (AECG). The apnea hypopnea index (AHI) was calculated from EDR and PSG respectively. With EDR assessments, 77 subjects were determined as SAHS (+), 43 were diagnosed as SAHS (-). The diagnostic accordance rate was 87.5% and the area under curve was 0.938. The coefficient correlation of AHI between EDR and PSG was 0.879 (P <0.001), while the correlation of maximum apnea and hypopnea time duration were 0.716 (P <0.001) and 0.281 (P <0.005), respectively. All correlations were statistically significant (P <0.01). EDR can be used as a practical tool for the diagnosis of SAHS.

[Types and risk factors of arrhythmia on young patients with acute coronary syndrome in Henan province].

OBJECTIVE: The types and risk factors of arrhythmia were analyzed on acute coronary syndrome (ACS) patients under the age of 44 years who were hospitalized in Henan province between September 2009 to June 2012. METHODS: Medical records of eligible patients were obtained from the information system of the First Affiliated Hospital of Zhengzhou University teleconsultation information center. Middle aged and elderly ACS patients who were hospitalized at the same period served as controls. Data on arrhythmia types, blood pressure, thyroid disease, respiratory sleep apnea syndrome, smoking history, history of alcohol consumption, eating habits, family history of early-onset arrhythmia, laboratory tests were analyzed. RESULTS: (1) Arrhythmia was detected in 110 out of young ACS patients (55%), which was significantly lower than that in the elderly ACS patients (71.05%, P < 0.01). (2) The top three arrhythmias in young ACS patients were: sinus tachycardia (30.50%), the premature ventricular contractions (19.00%), atrial flutter/atrial fibrillation (16.50%). Incidence of sinus tachycardia, atrial flutter/atrial fibrillation were significantly higher while incidence of ventricular tachycardia, ventricular fibrillation, paroxysmal supraventricular tachycardia were significantly lower in young ACS patients than in middle-aged ACS patients (all P < 0.05). The incidence of sinus tachycardia was higher while incidence of ventricular premature accelerated ventricular spontaneous cardiac rhythm, ventricular tachycardia, ventricular fibrillation, non-paroxysmal supraventricular tachycardia, atrial flutter/atrial fibrillation, paroxysmal supraventricular tachycardia, sinus bradycardia, nodal escape, atrioventricular block were significantly lower in young ACS patients than in elderly ACS patients (all P < 0.05). (3) Body mass index, incidence of smoking, coronary three-vessel disease, drinking, eating salty foods, thyroid dysfunction, sleep apnea were significantly higher in youth ACS patients with arrhythmia than in young ACS patients without arrhythmia (all P < 0. 05). (4) Logistic regression analysis found that number of diseased coronary vessels (OR = 24.293), smoking (OR = 1.112) and alcohol consumption (OR = 1.039) were independent risk factor for developing arrhythmia in young ACS patients from Henan province. CONCLUSIONS: The main types of arrhythmia are sinus tachycardia, premature ventricular contractions, atrial flutter/atrial fibrillation and the major risk factors related to the arrhythmia are number of diseased coronary vessels, smoking and alcohol consumption in young ACS patients from Henan province.

Re-evaluation of transvenous lead extraction with modified standard technique: a prospective study in 229 patients.

As new-type powered sheaths are expensive and unavailable, the standard lead extraction techniques remain the mainstay in clinical applications in many countries. The purpose of this study was to re-evaluate the clinical application of the standard lead extraction techniques and equipment, and make some procedural modifications and innovations. In our center, between January 2006 and May 2012, 229 patients (median, 66 years) who underwent lead extraction due to infection and lead malfunction were registered and followed up prospectively with respect to clinical features, reasons for lead extraction, technical characteristics, and clinical prognosis. A total of 440 leads had to be extracted transvenously by using special tools from 229 patients (male, 72.1%). Vegetations ≥1 cm were detected in six patients. Locking Stylets were applied for 398 (90.5%) leads. Telescoping dilator polypropylene sheaths and counter traction technique were used for 202 (45.9%) leads due to lead adhesion, and the mean implant duration of the 202 leads was longer than the other 238 leads (48.9±22.6 vs. 26.6±17.8 months; P <0.01). In addition, modified isolation and snare techniques were used for 56 leads (12.7%). Minor and major procedure-related complications occurred in three (1.3%) and four (1.7%) cases respectively, including one death (0.4%). Severe lead residue occurred in one case. Complete procedural success rate was 96.1% (423/440), and clinical success rate was 98.9% (435/440). The median follow-up period was 18 (1-76) months. No infection- and procedure-related death occurred in our series. Our data demonstrated that high clinical success rate of transvenous lead extraction can be guaranteed by making full use of the standard lead extraction techniques and equipment with individualized modifications.

[Population characteristics and impact on heart rate variability, heart rate and blood pressure of passive smoking].

OBJECTIVE: To investigate the basic characteristics of passive smoking population, and the impact of passive smoking on heart rate variability, heart rate and blood pressure. METHODS: Eighty-six passive smokers [mean age: (52.4 ± 7.6) years] were recruited from patients and their relatives who visited cardiovascular outpatient department and excluded structural heart disease between June 2010 and June 2012, 80 normal subjects who were not exposed to smoking served as controls. Questionnaire survey, 24 hours ambulatory electrocardiogram examination and blood pressure measurement were performed in all recruited subjects. RESULTS: (1) Non-marriage rate [18.60% (16/86) vs. 3.75% (3/80), P < 0.01] was significantly higher while education level were significantly lower in passive smoking group than in control group. Passive smokers were more likely service industry workers [29.07% (25/86) vs. 15.00% (12/80), P < 0.05] and had longer daily working time [(7.56 ± 1.24) h vs. (6.02 ± 0.96) h, P < 0.01], and were less likely to be professional technology industry employers [20.93% (18/86) vs. 36.25% (29/80), P < 0.05] and managers [13.95% (12/86) vs. 38.75% (31/80), P < 0.01] compared to controls. The main place of passive smoking was workplace (67.44%, 58/86), entertainment venues (63.95%,55/86), restaurants (48.84%, 42/86). (2) Standard of the normal sinus RR intervals (SDNN), the normal consecutive sinus RR interval difference between the root-mean-square (rMSSD) and adjacent the difference between the RR interval>50 ms the number of share the percentage (PNN50) were significantly lower in passive smoking group than in the control group (all P < 0.05). Every 5 min average of the standard deviation of sinus RR cycle (SDNN index) and 24 h every 5 min sinus RR interval mean standard deviation (SDANN) were similar between the 2 groups (all P > 0.05). Ultra-low-frequency power (VLF), low frequency power (LF), high frequency power (HF) and LF/HF were significantly lower in passive smoking group than in the control group (all P < 0.01). (3) Heart rate and diastolic blood pressure were significantly higher in passive smoking group than in control group (all P < 0.05) while systolic blood pressure was similar between the 2 groups (P > 0.05). CONCLUSIONS: Marriage status, education level, profession and daily working time are independent determinants for passive smoking. Passive smoking mainly occurred in the workplace, entertainment venues and restaurants. Passive smoking is linked with reduced heart rate variability, increased 24 h average heart rate and diastolic blood pressure.

A novel deletion-frameshift mutation in the S1 region of HERG gene in a Chinese family with long QT syndrome.

BACKGROUND: The congenital Long QT syndrome (LQTS) is a hereditary cardiac channelopathy that is characterized by a prolonged QT interval, syncope, ventricular arrhythmias, and sudden death. The chromosome 7-linked type 2 congenital LQTS (LQT2) is caused by gene mutations in the human ether-a-go-go-related gene (HERG). METHODS: A Chinese family diagnosed with LQTS were screened for KCNQ1, HERG and SCN5A, using polymerase chain reaction (PCR), direct sequencing, and clong sequencing. We also investigated the mRNA expression of the HERG gene. RESULTS: We identified a novel I414fs + 98X mutation in the HERG gene. The deletion mutation of 14-bp in the first transmembrane segment (S1) introduced premature termination codons (PTCs) at the end of exon 6. This mutation would result in a serious phenotype if the truncated proteins co-assembled with normal subunit to form the defective channels. But only the proband was symptomatic. CONCLUSIONS: We found that the mRNA level of the HERG gene was significantly lower in I414fs + 98X carriers than in noncarriers. We found a novel I414fs + 98X mutation. The mRNA level supports that NMD mechanism might regulate the novel mutation.

Implantable defibrillator lead extraction with optimized standard extraction techniques.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) leads might not be extracted especially in developing countries because of the high cost and lack of specialized tools. We aimed to evaluate transvenous extraction of ICD leads using optimized standard techniques. METHODS: We prospectively analyzed clinical characteristics, optimized extraction techniques and the feasibility of extraction for 40 patients (33 males; mean age 47.9 ± 16.1 years) with 42 ICD leads. RESULTS: Complete procedural success rate was 95.2% (40/42), and the clinical success rate was 97.6% (41/42). One ICD lead required cardiothoracic surgery. Minor complications occurred in three cases (7.5%), and no major complications or death occurred. Locking stylets were used to extract most leads (34, 81.0%) and almost half of the leads (20, 47.6%) required mechanical dilatation to free fibrotic adhesions; these leads had been implanted for a longer period of time than the others (43.7 ± 18.2 vs. 18.4 ± 13.4 months, P < 0.05). Three-quarters of the leads (30, 71.4%) were extracted with locking stylets plus manual traction (12, 28.6%), or mechanical dilatation with counter-traction (18, 42.8%) by the superior vena cava approach and one-quarter of the leads (11, 26.2%) were removed by optimized snare techniques using the femoral vein approach. Median extraction time was 20 min (range 2-68 min) per lead. Linear regression analysis showed that the extraction time was significantly correlated with implant duration (r = 0.70, P < 0.001). Median follow-up was 14.5 months (range 1-58 months), no infection, or procedure-related death occurred in our series. CONCLUSIONS: Our optimized procedure for transvenous extraction of ICD leads provides a practical and low-cost method for standard procedures.

Elderly patients and coronary heart disease on response to treadmill exercise test.

To study the response of the cardiovascular system, to exercise tolerance in-patients over 75 years old with coronary heart disease (CHD), and to evaluate the significance of the parameters of the treadmill exercise test (TET). 110 patients received TET and coronary artery angiography. They were divided into two groups: the elderly patients group included 50 patients over 75 years old, and the control group included 60 patients under 60 years old. (1) With aging, there were much more CHD patients in the positive TET (P < 0.05) than in the negative TET (P > 0.05). (2) The parameters of TET for the elderly CHD patients group, included exercise time, peak heart rate, and the onset of ST depression, were lower than the control group (P < 0.05). There was no statistical significance between the two groups in the extent and duration of ST depression (P < 0.05). (1) In TET, the elderly patients had the higher diagnostic value on CHD. (2) The elderly patients with CHD had the lower endurance to exercise test.

First report of HGD mutations in a Chinese with alkaptonuria.

Alkaptonuria (AKU) is one of the first prototypic inborn errors in metabolism and the first human disease found to be transmitted via Mendelian autosomal recessive inheritance. It is caused by HGD mutations, which leads to a deficiency in homogentisate 1,2-dioxygenase (HGD) activity. To date, several HGD mutations have been identified as the cause of the prototypic disease across different ethnic populations worldwide. However, in Asia, the HGD mutation is very rarely reported. For the Chinese population, no literature on HGD mutation screening is available to date. In this paper, we describe two novel HGD mutations in a Chinese AKU family, the splicing mutation of IVS7+1G>C, a donor splice site of exon 7, and a missense mutation of F329C in exon 12. The predicted new splicing site of the mutated exon 7 sequence demonstrated a 303bp extension after the mutation site. The F329C mutation most probably disturbed the stability of the conformation of the two loops critical to the Fe(2+) active site of the HGD enzyme.

[Effect of the smoking cessation services in the out-patient department for patients with coronary heart disease].

OBJECTIVE: To evaluate the effects and clinical prognosis of out-patient department-based smoking cessation services for coronary heart disease (CHD) patients. METHODS: A total of 140 smoking patients diagnosed with coronary heart disease in our cardiovascular department were randomly divided into the intensive smoking cessation clinic follow-up group (intervention group, patients were informed on the importance and methods to quit smoking at the first visit and reminded for that at months interval for 6 months, n = 70) and the conventional treatment group (control group, n = 70). After 6 months, the smoking status, cardiovascular event rates, drug usage, out-patient medical costs and quality of life were compared between the two groups. RESULTS: Age, gender, concomitant diseases, drug usage were similar between the two groups at baseline (all P > 0.05). After 6 months, smoking quit rate [34.2% (24/70) vs. 5.7% (4/70), P < 0.01], drug use rates: lipid-lowering drugs [95.3% (67/70) vs. 80.4% (56/70)], ß blockers [82.4% (57/70) vs. 41.3% (28/70)], and ACEI/ARB [61.4% (43/70) vs. 34.4% (24/70)] were significantly higher in the intervention group than in the control group, while total cardiovascular event rates [21.4% (15/70) vs. 47.1% (33/70), P < 0.01] and out-patient medical costs (3789.3 RMB vs. 4984.2 RMB, P < 0.01) were significantly lower in the intervention group than in the control group. The quality of life scores derived from MYO health survey questionnaire was significantly higher in the intervention group than in the control group (P < 0.01). The top three reasons responsible for continuous smoking for all patients failed to quit smoking were: (1) others smoked more than me and still alive and healthy [90.3% (56/62)]; (2) smoking helped me to keep relaxed and reduce trouble in daily work and life [70.9% (44/62)]; (3) smoking was essential while chatting and drinking with friends [66.1% (41/62)]. The overall satisfactory rate to this smoking cessation program was 42.8% and the satisfactory rate was up to 50.0% by patients. CONCLUSIONS: Intensive outpatient smoking cessation follow-up program can significantly improve the smoking cessation rates, the guideline drug use rate and the quality of life while reduce medical costs for coronary heart disease patients.

Relationship between myocardial bridging and coronary arteriosclerosis.

The objective of the study was to explore the prevalence and characteristics of myocardial bridging in patients who underwent coronary angiography and to also evaluate the correlation between bridged coronary segments and atherosclerosis. For this purpose, clinical materials of 1,500 patients who had received coronary angiography were retrospectively analyzed. The location and length of the myocardial bridge were recorded as well as the extent and location of coronary artery stenosis was described. Segments proximal and distal to the bridging were evaluated for coronary arteriosclerosis as were the remaining coronary segments. We found that myocardial bridging was present in 179 (11.9 %) patients. Bridges were frequently (84.9 %) localized in the mid-distal segment of the left anterior descending (LAD) artery. Myocardial bridging was not considered a significant risk factor for coronary atherosclerosis (odds ratio 0.58) compared with traditional cardiovascular risk factors. The incidence of coronary arteriosclerosis in the distal segments was significantly less affected than the proximal segments (P < 0.01). It was, therefore, concluded that myocardial bridging frequently localized in the mid-distal segment of the LAD artery. The presence of myocardial bridging promotes proximal atherosclerosis but it is not an additional risk factor for coronary atherosclerosis.

The diagnostic value of treadmill exercise test parameters for coronary artery disease.

The aim of this study was to determine the diagnostic value of treadmill exercise test (TET) in patients with coronary heart disease (CHD) by comparing the diagnostic conclusions with coronary angiography (CAG). Patients (445) with CHD and suspected CHD underwent TET and CAG, and the corresponding diagnostic conclusions were compared. (1) Out of the 200 cases that had the positive result with TET, 150 cases had been diagnosed CHD by means of CAG; Out of the 245 cases that had the negative result during TET, only 39 cases had been diagnosed CHD by means of CAG. The sensitivity, specificity, positive predictive value, negative predictive value, the false positive incidence, the false negative incidence, and agreement rate in diagnosis of CHD by TET were 79.36, 80.40, 75.00, 84.08, 25.00, 15.92, and 80.00 %, respectively. The patients with multi-vessel disease had a higher positive rate of TET as compared with those with single-vessel disease (P < 0.05). (2) The parameters for 189 cases positive CAG (patients diagnosed CHD by CAG) and 256 cases negative CAG (the control group), including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than that of control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than in the control group (P < 0.05). (3) 189 cases positive CAG, include 87 cases of single coronary artery and 102 cases of binary or more coronary arteries (the control group). The parameters, including the general exercise time, peak heart rate, and the beginning time of ST depression, were lower than the control group (P < 0.05). However, the extent of ST depression and duration of ST depression were higher in these patients than the control group (P < 0.05). The TET is valuable for noninvasive diagnosis of CHD, especially for patients with multi-vessel disease.

Percutaneous extraction of leads from coronary sinus vein and branch by modified techniques.

BACKGROUND: Cardiac resynchronization therapy (CRT) device and coronary sinus (CS) lead extraction are required due to the occurrence of systemic infection, malfunction, or upgrade. Relevant research of CS lead extraction is rare, especially in developing countries because of the high cost and lack of specialized tools. We aimed to evaluate percutaneous extraction of CS leads by modified conventional techniques. METHODS: Of 200 patients referred for lead extraction from January 2007 to June 2011, 24 (12.0%) involved CS leads (24 CS leads). We prospectively analyzed clinical characteristics, optimized extraction techniques and feasibility of extraction. RESULTS: Complete procedural success was achieved in 23 patients (95.8%), and the clinical success in 24 patients (100.0%). The leading indication for CS lead extraction was infection (66.7%). Mean implant duration was (29.5 ± 20.2) months (range, 3 - 78 months). Sixteen CS leads (66.6%) were removed with locking stylets plus manual traction by superior transvenous approach. Mechanical dilatation and counter-traction was required to free fibrotic adhesions and extract 4 CS leads (16.7%), which had longer implant duration than other leads ((62.5 ± 12.3) vs. (22.9 ± 14.1) months, P < 0.05). Another 4 CS (16.7%) leads were removed by modified and innovative snare techniques from femoral vein approach. Median extraction time was 11 minutes (range, 3 - 61 minutes) per CS lead, which had significant correlation with implant duration (r = 0.8, P < 0.001). Sixteen patients (66.6%) were reimplanted with new devices at a median of 7.5 days after extraction. Median followed-up was 23.5 months (range, 8 - 61 months), three patients died due to sudden cardiac death (26 months), heart failure (45 and 57 months, respectively). CONCLUSION: The modified procedure was proved to be practical for percutaneous extraction of CS leads, especially in developing countries lacking expensive powered sheaths.

Effects of ibutilide on canine cardiac pacing threshold and on induction rates of atrial fibrillation.

This study aims to observe the effects of ibutilide on canine cardiac pacing threshold and on induction rates of atrial fibrillation. Eighteen mongrel dogs were anesthetized and administrated with ibutilide. The pacing thresholds and induction rates of atrial fibrillation were measured with and without ibutilide (10-min infusion dose was 0.10 mg kg(-1), followed by a maintaining dose of 0.01 mg min(-1) 30 min later). This study found that ibutilide increases pacing thresholds in dogs. Moreover, there were significant differences between pacing thresholds with and without ibutilide (P < 0.05). Further, ibutilide significantly reduces the induction rates of atrial fibrillation (P < 0.05). Our findings indicate that pacing voltage changes should be closely monitored in patients taking anti-arrhythmic drugs, who are treated with cardiac stimulation or have undergone pacemaker implantation. We also found that ibutilide is an effective drug in preventing or controlling atrial fibrillation.

Effect of ibutilide on the canine cardiac conduction system.

The objective of the study was to evaluate the effect of ibutilide on canine cardiac sinoatrial and atrioventricular nodes (AVNs). For this purpose, 18 mongrel dogs were injected intravenously with ibutilide and the changes in heart rate, sinus node recovery time, and AVN were measured. Our data show that ibutilide administration caused significant suppression of the sinus atrial node, the peak response time was 20-30 min, and the heart rate was restored to pre-drug administration level. After receiving ibutilide, 1 animal had a 5 s sinus pause, and after 5 min of ibutilide administration, 1 dog showed 2:1 atrioventricular conduction. Therefore, it was concluded that ibutilide had a suppressive effect on the sinoatrial node and AVN.

Ventricular synchronicity: observations comparing pulse flow and tissue Doppler assessment in a Chinese healthy adult cohort.

BACKGROUND: Mechanical asynchrony is an important parameter in predicting the response to cardiac resynchronization therapy, but detailed knowledge about cardiac timing in healthy persons is scarce. Therefore, in the current study, we sought to investigate the physiological status of interventricular synchronicity using pulse wave flow and tissue Doppler imaging in a healthy Chinese population. METHODS: Eighty-eight healthy volunteers underwent standard flow and tissue Doppler echocardiographic examinations. Ventricular inflow and outflow pulse wave flow Doppler patterns were recorded together with annulus pulse tissue Doppler imaging. Time intervals from the beginning of the QRS complex to the onset, peak and end of each wave were measured. RESULTS: The onsets of systole between left and right ventricles were highly synchronized by both imaging modalities. However, the left ventricle reached the peak flow ejection and peak mechanical contraction earlier than the right ventricle, (165.61 ± 26.23) ms vs. (204.3 ± 34.55) ms (P < 0.01) and (133.62 ± 26.19) ms vs. (191.25 ± 38.47) ms (P < 0.01). Time to peak early diastolic relaxation was earlier in the left ventricle than in the right heart, (500.23 ± 56.52) ms vs. (524.94 ± 47.42) ms (P < 0.01). CONCLUSIONS: Left and right ventricles were well synchronized at the onsets of systole and diastole even though interventricular peak systolic and peak early diastolic dyssynchrony was observed in healthy people by pulse wave Doppler imaging. In addition, diastolic timing events were slightly affected by age and gender.