Biomedical subjects

Ke-ping Chen

Publications and source records attributed to Ke-ping Chen.

6 recordsLinked to original sources

PubMed2006

Short-term effect of cardiac resynchronization therapy in patients with ischaemic or nonischaemic cardiomyopathy.

BACKGROUND: Patients with heart failure were candidates for cardiac resynchronization therapy (CRT) regardless of underlying aetiology. This study observed the effect of CRT in patients with ischaemic or nonischaemic cardiomyopathy. METHODS: One hundred and forty-two patients with refractory chronic heart failure and left bundle branch block received cardiac resynchronization therapy, 91 men and 51 women, average age 60 years. Left ventricular ejection fraction (LVEF) was severely depressed (mean 29%), left ventricular end diastolic diameter (LVEDD) enlarged (mean 72 mm) and QRS width was lengthened (mean 147 ms). Ninety-eight had nonischaemic cardiomyopathy and 44 had ischaemic cardiomyopathy. RESULTS: After cardiac resynchronization therapy, the heart function was significantly improved. The mean LVEF increased from 29% to 36% after pacing. In patients with nonischaemic cardiomyopathy, the LVEF was improved from 28% to 37%, and in patients with ischaemic cardiomyopathy, the LVEF was improved from 30% to 36%. No significant difference of the improvement was found between the two groups (P > 0.05). CONCLUSIONS: Cardiac resynchronization therapy could significantly improve cardiac function in patients with chronic heart failure regardless of the underlying heart disease.

Bundle-Branch Block↗

PubMed2006

Impact of automatic threshold capture on pulse generator longevity.

BACKGROUND: The automatic, threshold tracking, pacing algorithm developed by St. Jude Medical, verifies ventricular capture beat by beat by recognizing the evoked response following each pacemaker stimulus. This function was assumed to be not only energy saving but safe. This study estimated the extension in longevity obtained by AutoCapture (AC) compared with pacemakers programmed to manually optimized, nominal output. METHODS: Thirty-four patients who received the St. Jude Affinity series pacemaker were included in the study. The following measurements were taken: stimulation and sensing threshold, impedance of leads, evoked response and polarization signals by 3501 programmer during followup, battery current and battery impedance under different conditions. For longevity comparison, ventricular output was programmed under three different conditions: (1) AC on; (2) AC off with nominal output, and (3) AC off with pacing output set at twice the pacing threshold with a minimum of 2.0 V. Patients were divided into two groups: chronic threshold is higher or lower than 1 V. The efficacy of AC was evaluated. RESULTS: Current drain in the AC on group, AC off with optimized programming or nominal output was (14.33 +/- 2.84) mA, (16.74 +/- 2.75) mA and (18.4 +/- 2.44) mA, respectively (AC on or AC off with optimized programming vs. nominal output, P < 0.01). Estimated longevity was significantly extended by AC on when compared with nominal setting [(103 +/- 27) months, (80 +/- 24) months, P < 0.01). Furthermore, compared with the optimized programming, AC extends the longevity when the pacing threshold is higher than 1 V. CONCLUSION: AC could significantly prolong pacemaker longevity; especially in the patient with high pacing threshold.

Aged↗

PubMed2006

Assessment of cardiac function and synchronicity in subjects with isolated bundle branch block using Doppler imaging.

BACKGROUND: Using tissue Doppler imaging and conventional echocardiographic technique, we examined the cardiac function and synchronicity in individuals with isolated right bundle branch block (RBBB) or left bundle branch block (LBBB) and assessed the relationship between QRS duration and synchronicity. METHODS: Subjects with isolated RBBB (n = 20), LBBB (n = 10) and normal controls (n = 20) were studied with conventional echocardiography and tissue Doppler imaging. The difference between aortic and pulmonary preejection intervals was defined as interventricular delay. Parameters in septum and lateral wall were measured using tissue Doppler imaging, including peak sustained systolic velocity (S(M)), peak early (E(M)) and late (A(M)) diastolic velocities as well as time to peak velocities (T(S), T(E) and T(A)). RESULTS: Subjects with LBBB had lower S(M) and longer T(S) than did the RBBB and control groups (P < 0.05, P < 0.001 respectively). A significant difference was observed in E(M), being the lowest in the LBBB and the highest in the control group (P < 0.05). Moreover, T(E) was longer in the LBBB group compared with the other two groups (P < 0.001). Both A(M) and T(A) were similar among three groups (P > 0.05). In the bundle branch block groups, one ventricle lagged about 40 ms behind the other. A significant correlation was found between interventricular delay and QRS duration (r = 0.713, P < 0.001). CONCLUSIONS: Cardiac ventricles were not well synchronized with one ventricle lagging about 40 ms behind the other in subjects with LBBB or RBBB, even though only LBBB group showed barely perceptible, impaired cardiac function. In addition, QRS duration and cardiac asynchronicity were positively correlated.

Adult↗

PubMed2006

Incidence and causes of inappropriate detection and therapy by implantable defibrillators of cardioversion in patients with ventricular tachyarrhythmia.

BACKGROUND: Implantable cardioverter defibrillator (ICD) is the only effective therapy in patients with life threatening ventricular arrhythmias. Inappropriate detection and therapy by ICDs are the most common causes of side effects that affect the quality of life in ICD recipients. This study evaluated the incidence and causes of inappropriate detection and therapy by ICDs in patients in our hospital. METHODS: From January 2000 to December 2005, fifty patients who received ICD implantation for ventricular arrhythmias for prevention of sudden cardiac death were evaluated in this study. Each ICD was programmed using clinical arrhythmic and cardiac data of the patient before discharge. Patients were followed up by standard schedule after implantation and all data retrieved from each device were collected and saved for further analysis. RESULTS: No arrhythmic event was detected in 12/50 (24%) patients during the period of follow-up. Among the remaining patients, 11 (22%) experienced inappropriate detections and therapies during follow-up in this study. ICD detected 383 ventricular tachyarrhythmia (VT) and 108 ventricular fibrillation (VF) episodes and delivered 678 therapies. In VT group, ICD delivered 413 antitachycardiac pacings (ATPs) and 118 shocks, among which 78 ATPs and 9 shocks were initiated by 55/383 (14.3%) inappropriate detections. In VF group ICD delivered 147 shocks, among which 56 shocks were initiated by 28/108 (26.9%) inappropriate detections. Overall, more than 50% of these episodes were caused by atrial fibrillation (AF) with rapid ventricular response, followed by electromagnetic or myopotential interference. In addition, most inappropriate therapies occurred within one year after ICD implantation. CONCLUSIONS: About one fifth of patients experienced ICD inappropriate detection and therapy after implantation. The main cause was AF with rapid ventricular response, followed by electromagnetic or myopotential interference.

Adult↗

PubMed2006

Complications of cardiac resynchronization therapy in patients with congestive heart failure.

BACKGROUND: Previous clinical studies have suggested that patients with congestive heart failure and intraventricular conduction delay could benefit from cardiac resynchronization therapy (CRT). Implantation of left ventricular lead is a complex procedure with some potential for complications. This study was conducted to analyse the complications of CRT in patients with congestive heart failure. METHODS: Totally 117 patients, 86 males and 31 females, mean age of 53 years, with congestive heart failure and intraventricular conduction delay were enrolled in this study. Venography was performed on all patients. Different types of coronary sinus leads were used to pace the left ventricle. RESULTS: Left ventricular lead was attempted to implant through coronary sinus for all the 117 patients and was successfully implanted in 111 patients. The success rate was 94.9%. Main complications rate was 6.8%, including coronary sinus dissection in 4 patients, phrenic nerve stimulation required lead repositioning in 2 patients and lead dislodgement in 2 patients. CONCLUSIONS: It is feasible and safe to pace left ventricle through coronary sinus. However, there are some procedural complications.

Angioplasty, Balloon, Coronary↗

PubMed2005

[Clinical study on 29 pacemaker and defibrillator lead fractures].

OBJECTIVE: To analyze major probable causes, locations and remedies of lead fractures in implanted pacemaker and implanted cardioverter defibrillator (ICD) . METHODS: From January 1982 to November 2004, on all the pacemakers and ICDs implanted at this hospital, lead fractures were detected timely by regular telemetric programmed testing, chest radiography and electrocardiography. Appropriate remedial actions were given and follow up visits were done to verify the results. RESULTS: Of all the 4698 pacemakers and 161 ICDs, there were 29 lead fractures on 31 leads with an incidence rate of 0.6%. The incidence rate of lead fracture was 0.9% for pacemakers/defibrillators implanted by subclavian venipuncture, while it was 0.4% for pacemakers/defibrillators implanted by cephalic venotomy (P = 0.04). Fracture locations: 22 cases at the sub clavicle, 6 cases in the pacemaker pocket, and 1 case in the right ventricle. Among the 29 cases, 24 were implanted with additional new leads, 3 cases whose atrial leads were fractured were switched from DDD mode to VVI. All the patients were followed up for an average of 5.6 months +/- 16.1 months. In one patient, the lead was removed through thoracotomy due to infection of exposed lead. CONCLUSIONS: Cephalic venotomy is the first choice for pacemaker and ICD implantation, and the second choice is subclavian venipuncture in the outer part of subclavian vein, which has a higher incidence rate of lead fracture. Most lead fractures are detected at the region of medial subclavian. Regular follow-up can help timely detect fractures, so that the cases can be dealt with properly.

Adult↗