Reliability of Transesophageal Pacing in the Assessment of Sinus Node Function in Patients with Sick Sinus Syndrome

The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node function in patients with sick sinus syndrome (SSS). In 17 patients with SSS (study group) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and, 24 hours later, by transesophageal pacing. In another group of 17 patients with SSS (control group), we compared the results obtained by two endocavitary studies. In "study group", sinus cycle length (SCL) and corrected sinus node recovery time (CSRT) did not show significant differences between the two studies both in the basal state and after autonomic blockade, whereas sinoatrial conduction time (SACT) was more prolonged during esophageal pacing (P less than 0.01). In "control group", sinus node measures did not show significant differences between the two studies. In the "study group," the following coefficients of correlation were obtained in the basal state; SCL, r = 0.65, CSRT, r = 0.57, SACT, r = 0.52 and after autonomic blockade: SCL, r = 0.95, CSRT, r = 0.62 and SACT, r = 0.53. In the basal state, the correlation for SCL and CSRT between the two studies was lower in the "study group" than in the "control group" (P less than 0.05), whereas after autonomic blockade the correlation for sinus node measures did not show significant differences between the two groups of patients. These data suggest that transesophageal study influences the autonomic tone regulating the sinus node; however, it is not responsible for important variations in sinus node measures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lack of Influence of Atrioventricular Delay on Stroke Volume at Rest in Patients with Complete Atrioventricular Block and Dual Chamber Pacing

Dual chamber pacing (DDD) maintains atrioventricular (AV) sequence; AV delay programmability modifies the relationship between atrial and ventricular contraction. To evaluate the hemodynamic effects of such a modification, ten patients with a DDD unit for complete AV block were studied by time-motion (M-mode) and Doppler echocardiography during inhibited ventricular pacing (VVI), atrial-triggered ventricular pacing (VDD) and atrioventricular sequential pacing (DVI) at different AV delay (90, 140, 190, 240 msec). A significant improvement in stroke volume (SV) (15%-20%, P less than 0.05) was seen during DDD versus VVI pacing; no changes, however, were observed in the same patient with different AV delay or during DVI versus VDD pacing. These data suggest that programming of AV delay does not affect systolic performance at rest; longer diastolic filling times recorded during DDD pacing with "short" AV delay (90-140 msec) do not seem to be a hemodynamically relevant epi-phenomenon of PM programming.     

Neuroimaging in childhood arterial ischaemic stroke: evaluation of imaging modalities and aetiologies

Aim The aim of this study was to describe neuroimaging patterns associated with arterial ischaemic stroke (AIS) in childhood and to differentiate them according to stroke aetiology. Method Clinical and neuroimaging (acute and follow‐up) findings were analysed prospectively in 79 children (48 males, 31 females) aged 2 months to 15 years 8 months (median 5y 3mo) at the time of stroke by the Swiss Neuropaediatric Stroke Registry from 2000 to 2006. Results Stroke was confirmed in the acute period in 36 out of 41 children who underwent computed tomography, in 53 of 57 who underwent T2‐weighted magnetic resonance imaging (MRI) and in all 48 children who underwent diffusion‐weighted MRI. AIS occurred in the anterior cerebral artery (ACA) in 63 participants and in all cases was associated with lesions of the middle cerebral artery (MCA). The lesion was cortical–subcortical in 30 out of 63 children, cortical in 25 out of 63, and subcortical in 8 of 63 children. Among participants with AIS in the posterior circulation territory, the stroke was cortical–subcortical in 8 out of 16, cortical in 5 of 16, and thalamic in 3 out of 16 children. Interpretation AIS mainly involves the anterior circulation territory, with both the ACA and the MCA being affected. The classification of Ganesan is an appropriate population‐based classification for our Swiss cohort, but the neuroimaging pattern alone is insufficient to determine the aetiology of stroke in a paediatric population. The results show a poor correlation between lesion pattern and aetiology.     

Influence of Age, Lead Axis, Frequency of Arrhythmic Episodes, and Atrial Dimensions on P Wave Triggered SAECG in Patients with Lone Paroxysmal Atrial Fibrillation

Signal-averaged P wave of 42 patients with lone paroxysmal atrial fibrillation (PAF) and 29 normal subjects (N) were recorded, using three orthogonal leads and analyzed in the time and frequency (entire P wave or a 100-ms segment ranging from 75 ms before to 25 ms after the end of P wave) domains. PAFs were divided into a group of 12 having ≥ 2 attacks a month (HF) and a group of 30 having ≤ 2 attacks a year (LF). Statistically significant differences were absent with regard to ages of PAF and N; ages of HF, LF, and N at the time of signal-averaged ECG; ages of HF and LF at the time of the first arrhythmic episode; and elapsed times from the first episode. Length of P wave and some frequency-domain parameters were found to be significantly correlated with age. PAF showed a significantly longer duration of P wave in the frontal plane using the time-domain analysis. Frequency analysis was found to be useful in evaluating the influence of attack frequency. HF showed significantly higher values of some frequency-domain parameters than LF and N, while the three groups did not differ for time-domain analysis. P wave duration and frequency content of the three orthogonal leads proved to be significantly different in PAF and N. Right and left atrial echocardiographic dimensions proved to be higher (even if within normal limits) in HF than in LF and N. Results suggest that frequency analysis should be performed on the entire P wave.