Clinical Characteristics of Patients with Permanent Pacemaker Associated with Lead Thrombi

BACKGROUND AND OBJECTIVES: The formation of thrombi on a permanent pacemaker lead has been reported as a rare complication following the implantation of a permanent pacemaker. However, there is little information about the complications related to modern cardiac pacing. The purpose of this study was to evaluate the factors associated with the formation of a lead thrombosis following the implantation of a permanent pacemaker (P-PM). SUBJECTS AND METHODS: We retrospectively reviewed the medical records of 14 patients (M:F= 6:8, mean age=46+/-11) with P-PM lead thrombus that were detected with a transthoracic echocardiography. The clinical features, type of pacemaker and echocardiographic findings of these patients were analyzed. RESULTS: All thromb us formations had developed in the right atrium (RA), and/or superior vena cava (SVC)(100%, n=14), were mainly in the proximal portion of the RA (71.4%, n=10) and on the ventricular lead (64.3%, n=9). 12 of 14 patients (85.7%), The lead thromboses were atrial fibrillation, with tachy-brady syndrome or sinus pause. Three of the patients had a total SVC obstruction and 1 a thrombus with aspergillosis. The lead thrombus in one patient was completely resolved after thrombolytic treatment. There were no significant differences in the incidences of lead thrombosis in relation to the number of implanted leads, insulation type, echocardiographic parameters. CONCLUSION: Lead thromboses might not be a rare complication following the implantation of a P-PM, and frequently occur in the right atrium of patients with atrial pathology. The necessity for thrombolytic therapy in patients with a lead thrombus should be further investigated.

Fate of Atrial Myocardium in Severe Mitral Regurgitation in the Aspect of Programmed Cell Death

BACKGROUND AND OBJECTIVES: From the view point of the molecular aspects, the fate of long standing pressure and volume overloaded atrium in severe MR has not been evaluated. This study was performed to elucidate whether apoptosis of right atrial myocytes is related to atrial changes. SUBJECTS AND METHODS: The medical records of 16 patients (M: F=8: 8, mean age=52+/-12), with severe MR having undergone valve replacement surgery, were retrospectively reviewed. The subjects were divided into 2 groups according to the duration of their symptoms (group I, symptom duration less than 12 months, n=10 and group II, more than 12 months, n=6). Using the atrial myocardium specimens obtained during surgery, TUNEL assays and immunohistochemical staining were performed for the expressions of Fas, Bax and the Bcl family. RESULTS: Apoptotic indices of TUNEL assay were 31.1+/-12.6 and 4.9+/-4.3% in groups I and II, respectively (p<0.01). The Fas expressions were 42.1+/-14.4 and 27.8+/-10.5% in groups I and II, respectively (p<0.05), but in group I, with atrial fibrillation (AF), was 49.3+/-6.9%, which was higher than the 29.2+/-12.5% in group I without AF and group II (p<0.001). The Bax expression in group I patients with a left atrial size less than 4 cm was 19.2+/-10.7%, which was higher than the 7.2+/-6.2% in group I with a left atrial size more than 4 cm and group II (p<0.05). CONCLUSION: Programmed cell death of the atrial myocardium, in severe MR, might be an early molecular pathological change rather than the late sequelae. The causality between programmed cell death and electrical and structural changes of the atrium should be further investigated.

Intraoperative assessment of Native Coronary Artery and Bypass Graft Flow Using a 15 MHz Linear Array Transducer

BACKGROUNDS: The internal mammary artery graft (IMAG) showed a gradual transition in the phasic flow pattern from predominant systolic velocity proximally at the origin from the subclavian artery to the predominant diastolic velocity distal to the anastomosis with coronary artery. IMAG without significant stenosis showed a typical pulsed Doppler flow pattern similar to that of coronary artery characterized by a predominant diastolic component. On the other hand, patients with occluded IMAGs or IMAGs with severe stenosis, low velocity profiles were recorded during diastole with an increase in the systolic component. OBJECTIVES: Identifying abnormal graft flow intraoperatively could allow for immediate graft revision. The aim of this study was to test the feasibility of using a new ultrasound 15 MHz linear array transducer. METHODS: In six patients (M:F=4:2, mean age=69+/-11 yrs), a 15 MHz linear array probe with a sterile cover was placed directly on native coronary arteries and grafts after anatomosis. 2-dimensional image, color and pulsed Doppler signals of native coronary arteries, IMA, saphenous vein and penetrating intramyocardial coronary arteries (PICA) were observed. RESULTS: 1) 2-dimensional image and color flow signals of all grafts and native coronary arteries were visualized. 2) The flow pattern of pulsed Doppler signals of all native coronary arteries including PICA were diastolic dominant. 3) The diastolic dominant pattern typical of a patent grafts on pulsed Doppler were obtained at anastomosis site of graft vessels. 4) The intimal thickening of right coronary artery was also visualized on 2-dimensional images. CONCLUSION: A new echo Doppler probe can be useful for intraoperative assessment of graft flow during bypass surgery.

Clinical Significance of Slow Flow Velocity in the Distal Left Anterior Descending Coronary Artery Detected by Transthoracic Doppler Echocardiography

BACKGROUND AND OBJECTIVES: The aim of this study was to test whether flow velocity in the distal left anterior descending coronary artery (LAD) measured using transthoracic Doppler echocardiography (TTE) can predict pathologic coronary flow dynamics. SUBJECTS AND METHODS: We prospectively examined 222 subjects (mean age 57+/-9 yrs, M:F=132:90) including 55 subjects with myocardial infarction (MI group, mean age=57+/-9, M:F-45:10), 68 with typical angina (Angina group, mean age=62+/-8, M:F=44:24) and 99 with atypical chest pain and normal coronary angiogram (Control group, mean age=54+/-10, M:F=43+/-56). After obtaining tubular color flow signals of the distal LAD using TTE with a special preset program for a low velocity range, the peak (PDV) and mean (MDV) diastolic velocity as well as velocity time integral (VTI) were measured. The echocardiographic parameters of distal LAD flow were compared with the coronary angiographic findings including lesion classification according to ACC/AHA guidelines and the percent diameter stenosis. RESULTS: The average PDV was 20.3+/-9.7 cm/sec in patients with atypical chest pain and normal coronary angiogram, 16.8+/-8.5 cm/sec in patients with typical angina without myocardial infarction and 15.0+/-7.5 cm/sec in those with myocardial infarction (p<0.01 versus the MI group and Angina group, respectively). The PDV was found to be significantly related to the percent diameter stenosis (r=-0.292, p=0.002). The PDV in the group with complex lesion was significantly lower than that of the group with simple lesion. A value of PDV<14 cm/sec had a sensitivity of 76.6% and a specificity of 91.5% for predicting complex lesion of the LAD in groups including myocardial infarction and angina. CONCLUSION: Slow flow velocity in the distal LAD as demonstrated by TTE strongly predicts complex lesions. Baseline coronary flow velocity using TTE provides valuable information about the pathologic condition.