scholarly journals Gender and the relationship between ventricular repolarization and cardiac cycle length during 24-h Holter recordings

1997 ◽  
Vol 18 (6) ◽  
pp. 1000-1006 ◽  
Author(s):  
M. Stramba-Badiale ◽  
E. H. Locati ◽  
A. Martinelli ◽  
J. Courville ◽  
P. J. Schwartz
Keyword(s):  
Cycle Length ◽  
Cardiac Cycle ◽  
Ventricular Repolarization ◽  
The Relationship ◽  
Holter Recordings

scholarly journals Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 672
Author(s):  
Bruce A. Young ◽  
Skye Greer ◽  
Michael Cramberg
Keyword(s):  
Cerebrospinal Fluid ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Mean Amplitude ◽  
The Body ◽  
Body Waves ◽  
Lower Amplitude ◽  
Lateral Undulation ◽  
Recovery From Anesthesia ◽  
The Relationship

In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.

scholarly journals Cycle length of nonsustanied ventricular tachycardias among ICD patients: implications on subsequent appropriate therapies

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Javier Jiménez-Candil ◽  
Olga Duran ◽  
Armando Oterino ◽  
Jendri Pérez ◽  
Juan Carlos Castro ◽  
...  
Keyword(s):  
At Risk ◽  
Secondary Prevention ◽  
Beta Blocker ◽  
Cycle Length ◽  
Close Relationship ◽  
Appropriate Therapy ◽  
The Mean ◽  
Ventricular Tachycardias ◽  
The Relationship

Abstract Background ICD patients with episodes of nonsustained ventricular tachycardias (NSVT) are at risk of appropriate therapies. However, the relationship between the cycle length (CL) of such NSVTs and the subsequent incidence of appropriate interventions is unknown. Methods 416 ICD patients with LVEF < 45% were studied. ICD programming was standardized. NSVT was defined as any VT of 5 or more beats at ≥ 150 bpm occurred in the first 6 months after implantation that terminated spontaneously and was not preceded by any appropriate therapy. The mean follow-up was 41 ± 27 months. Results We analyzed 2201 NSVTs (mean CL = 323 ms) that occurred in 250 patients; 111 of such episodes were fast (CL ≤ 300 ms). Secondary prevention (HR = 1.7; p < 0.001), number of NSVT episodes (HR = 1.05; 95% CI 1.04–1.07; p < 0.001) and beta-blocker treatment (HR = 0.7; p = 0.04) were independent predictors of appropriate interventions; however, the mean CL of NSVTs was not (p = 0.6). There was a correlation between the mean CL of NSVTs and the CL of the first monomorphic VT: r = 0.88; p < 0.001. This correlation was especially robust in individuals with > 5 NSVTs (r = 0.97; p < 0.001), with an agreement between both values greater than 95%. Patients with any fast NSVT experienced a higher incidence of VF episodes (26%) compared to those without NVSTs (3%) or with only slow NSVTs (7%); p < 0.001. Conclusions Unlike the burden, the CL of NSVTs is not a predictor of subsequent appropriate interventions. However, there is a close relationship between the CL of NSVTs and that of arrhythmias that will later lead to appropriate therapies.

Kinetics of Cycle Length Dependence of Ventricular Repolarization:.

1995 ◽  
Vol 6 (3) ◽  
pp. 163-169 ◽  
Author(s):  
ERNST A. RAEDER ◽  
PAUL ALBRECHT ◽  
MICHAEL PERROTT ◽  
RICHARD J. COHEN
Keyword(s):  
Cycle Length ◽  
Ventricular Repolarization ◽  
Length Dependence ◽  
Kinetics Of

Motor cycles with phase III in antrum are associated with high motilin levels and prolonged gallbladder emptying

1993 ◽  
Vol 264 (4) ◽  
pp. G596-G600 ◽  
Author(s):  
M. F. Stolk ◽  
K. J. van Erpecum ◽  
A. J. Smout ◽  
L. M. Akkermans ◽  
J. B. Jansen ◽  
...  
Keyword(s):  
Bile Acid ◽  
Cycle Length ◽  
Phase Iii ◽  
Gallbladder Motility ◽  
Gallbladder Emptying ◽  
Motor Complex ◽  
Group 2 ◽  
Relationship Of ◽  
The Relationship ◽  
Group 1

We examined the relationship of interdigestive gallbladder emptying with the different phases of the migrating motor complex (MMC) and with plasma levels of cholecystokinin (CCK) and motilin. In 10 volunteers 20 cycles of the MMC were recorded. In 11 cycles phase III occurred in antrum and duodenum (group 1). In nine cycles phase III was observed only in duodenum (group 2). In group 1 gallbladder emptying started at 30% of total cycle length and continued until the end of the cycle. Maximal gallbladder emptying was 33.3 +/- 3.3% (SE). In group 2 gallbladder emptying also started at 30% of total cycle length but ended at 60%. Maximal gallbladder emptying in this group was 24.3 +/- 3.1% (P < 0.05). Motilin levels were higher in group 1 than in group 2 during phase IIB (240.1 +/- 28.5 and 142.1 +/- 30.9 pg/ml, respectively, P < 0.05) and during phase III (210.8 +/- 24.3 and 93.5 +/- 12.5 pg/ml, respectively, P < 0.05). We conclude that: 1) phase III activities starting in the antrum are preceded by greater and prolonged gallbladder emptying, higher motilin levels, and higher intraduodenal bile acid concentrations than phase III activities starting in the duodenum and 2) no relationship between interdigestive gallbladder motility and CCK levels could be demonstrated.

Reflex cardiovascular responses to chemoreceptor stimulation in conscious dogs with cardiac hypertrophy

1983 ◽  
Vol 245 (5) ◽  
pp. H871-H879
Author(s):  
P. A. Murray ◽  
S. F. Vatner
Keyword(s):  
Adrenergic Receptor ◽  
Cycle Length ◽  
Cardiac Cycle ◽  
Cardiovascular Responses ◽  
Conscious Dogs ◽  
Receptor Blockade ◽  
Coronary Resistance ◽  
Coronary Vasoconstriction ◽  
Reflex Activation ◽  
Adrenergic Receptor Blockade

Carotid chemoreceptor reflex activation (CCRA) has been previously shown to result in intense alpha-adrenergic peripheral vasoconstriction, a biphasic coronary vascular response characterized by an early vasodilation and a late alpha-adrenergic vasoconstriction, and a cholinergic increase in cardiac cycle length in normal conscious dogs. In the present study, we investigated the extent to which these reflex cardiovascular responses to CCRA are modified after the development of pressure-overload right ventricular (RV) hypertrophy induced by chronic (9-12 mo) pulmonary arterial stenosis. With heart rate constant and respiration allowed to vary spontaneously, the magnitude of the late CCRA-induced (intracarotid nicotine) increase (P less than 0.01) in right coronary resistance was markedly attenuated (P less than 0.01) in conscious dogs with RV hypertrophy [0.29 +/- 0.07 (SE) mmHg X ml-1 X min] compared with normal dogs (1.87 +/- 0.36). When respiration was controlled to eliminate pulmonary inflation reflex activation, the late CCRA-induced increase (P less than 0.01) in right coronary resistance was still found to be depressed (P less than 0.01) in the RV hypertrophy group (1.11 +/- 0.20 mmHg X ml-1 X min) compared with normal dogs (3.65 +/- 0.75). This late CCRA-induced right coronary vasoconstriction was not potentiated by beta-adrenergic receptor blockade but was abolished (P less than 0.01) by alpha-adrenergic receptor blockade. In contrast to the depressed right coronary vasoconstriction, the CCRA-induced alpha-adrenergic constriction (P less than 0.01) of the iliac arterial vascular bed was similar in both groups, and the cholinergic increase (P less than 0.01) in cardiac cycle length was enhanced (P less than 0.01) in the RV hypertrophy group compared with normal dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of vagus nerve on heart rate and ventricular contractility in chicken

1989 ◽  
Vol 256 (5) ◽  
pp. H1295-H1302
Author(s):  
S. A. Lang ◽  
M. N. Levy
Keyword(s):  
Vagus Nerve ◽  
Cycle Length ◽  
Cardiac Cycle ◽  
Ventricular Contractility ◽  
Ventricular Contraction ◽  
Vagus Stimulation ◽  
Constant Frequency ◽  
The Right ◽  
Contraction And Relaxation ◽  
Left Vagus

We determined the effects of vagus nerve stimulation on cardiac cycle length and on ventricular contraction and relaxation in 18 chickens anesthetized with pentobarbital. Right vagus stimulation at a constant frequency of 35 Hz prolonged cycle length by 190%, whereas left vagus stimulation at the same frequency increased cycle length by 136%. When one burst of stimuli was delivered to the right vagus nerve each cardiac cycle, but the timing of the stimuli was changed within the cardiac cycle, the response of the avian pacemaker cells varied substantially with the timing of the stimuli. Right and left vagus stimulation at a constant frequency of 20 Hz depressed ventricular contraction by 62 +/- 6 and 52 +/- 6%, respectively, and depressed ventricular relaxation by 56 +/- 7 and 53 +/- 7%, respectively. These results indicate that in the chicken the chronotropic effects of right vagus stimulation are greater than those of left vagus stimulation, whereas right and left vagus stimulation are approximately equipotent on ventricular contraction and relaxation.

Characterization of responses of neonatal sinus and AV nodes to critically timed, brief vagal stimuli

1991 ◽  
Vol 260 (2) ◽  
pp. H459-H464 ◽  
Author(s):  
S. Yamasaki ◽  
A. Stolfi ◽  
A. S. Pickoff
Keyword(s):  
Cycle Length ◽  
Cardiac Cycle ◽  
Gradual Increase ◽  
Latency Period ◽  
Atrial Pacing ◽  
Response Curves ◽  
Stimulus Train ◽  
Sinus Cycle Length ◽  
The Right

We studied the responses of sinus cycle length and atrioventricular (AV) nodal conduction to brief, critically timed vagal stimuli in 25 neonatal (9.6 +/- 3.1 days) canines. Vagal stimuli were delivered to the right or left decentralized cervical vagosympathetic trunk as either a single, brief stimulus train or a repetitive, phase-coupled train with both stimulation paradigms programmed to scan the entire cardiac cycle. The effects of brief vagal stimuli on cardiac cycle length were measured while the heart was beating spontaneously, and the vagal effects on AV nodal conduction were measured while the cycle length was held constant by atrial pacing at 300 ms. Neither changes in sinus cycle length nor AV nodal conduction demonstrated classical phase dependency, i.e., a gradual increase in the magnitude of the vagal response as stimuli are delivered progressively later in the cardiac cycle until the latency period (that point in the cardiac cycle at which vagal stimulation no longer affects the next cardiac cycle) is reached. Phase-response curves (PRCs) to single and repetitive stimuli typically exhibited either a flat response or a small decrease in magnitude as the latency period of the PRC was approached. Thus the neonatal sinus and AV node PRCs exhibit a different configuration than that reported in the adult.

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