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At least 847 records · Page 47Linked to original sources
PubMed2026

Conduction System Pacing Versus Right Ventricular Pacing in Patients With Atrioventricular Block and Anticipated High Pacing Burden.

Right ventricular pacing (RVP) in patients with atrioventricular (AV) block and high anticipated pacing burden is associated with pacing-induced cardiomyopathy (PICM) in approximately 12% to 20% of patients, whereas conduction system pacing (CSP) preserves more physiologic ventricular activation and may mitigate these consequences; the totality of contemporary randomized evidence has not been systematically pooled. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing CSP with RVP in patients with AV block or anticipated high ventricular pacing burden and a minimum 6-month follow-up, with co-primary outcomes of PICM incidence and change in left ventricular ejection fraction (&#x394;LVEF) and secondary outcomes of heart failure hospitalization (HFH), all-cause mortality, composite clinical endpoint, and paced QRS duration (PROSPERO CRD420261400227); random-effects meta-analysis used DerSimonian-Laird estimation. Five RCTs (LBBP-FAVOUR, CSPACE, Prague CSP, PACE-HF, STAY; N = 806) met inclusion criteria. CSP significantly reduced PICM (hazard ratio [HR] 0.30, 95% confidence interval [CI] 0.18 to 0.48; p <0.001; I&#xb2; = 0%; k = 4), was associated with greater LVEF preservation (pooled mean difference [MD] +4.41%, 95% CI +1.82 to +6.99; p = 0.001; I&#xb2; = 87%; k = 5), and reduced HFH (HR 0.24, 95% CI 0.12 to 0.48; p <0.001; I&#xb2; = 0%; k = 5). CSP shortened paced QRS duration (MD -27.5 ms, 95% CI -32.6 to -22.5; p <0.001; k = 5). All-cause mortality was numerically lower with CSP but did not reach significance (HR 0.57, 95% CI 0.29 to 1.12; p = 0.10; k = 4). In a prespecified sensitivity analysis restricting to multicenter trials with N &#x2265; 150, all findings were concordant with the primary analysis. In conclusion, CSP substantially reduces PICM, preserves LVEF, and reduces HFH compared with RVP in patients with AV block and anticipated high pacing burden, supporting its consideration as the preferred pacing strategy in appropriately selected patients.

Humans↗
PubMedDate not supplied

Diversity of the neuropathies in patients with non-insulin-dependent diabetes mellitus.

The relationships between cardiac autonomic neuropathies, diabetic somatic neuropathy, metabolic parameters, general parameters (such as age and duration of illness) and diabetic microangiopathy and macroangiopathy were investigated in 103 patients with non-insulin-dependent diabetes mellitus (NIDDM). Spearman's correlation coefficients were calculated for the comparisons of all the parameters of the neuropathies with all the other parameters. Variables were selected using a stepwise procedure and multiple regression analysis was carried out using these variables. The results of the regression analysis show that diabetic neuropathy is correlated with vascular parameters including blood pressure and pulse-wave velocity, as well as with parameters of sugar and lipid metabolism. The results confirm the diversity of the clinical characteristics of the neuropathies in patients with NIDDM and confirm that these neuropathies do not always occur in parallel.

Aged↗
PubMed1995

Decreased heart rate variability in amyotrophic lateral sclerosis.

Autoregressive spectral analysis of heart rate variability (HRV) was performed in 29 patients with amyotrophic lateral sclerosis (ALS) and 33 age-matched healthy subjects to evaluate the involvement of the autonomic nervous system. HRV analysis provides a means to recognize low (LF) and high (HF) frequency components, respectively mediated by sympathetic and parasympathetic heart control. An increase in the mean heart rate at rest (P < 0.001), a decrease in standard deviation of R-R interval as well as in PNN50 (P < 0.001), and an increase in the LF/HF component ratio (P < 0.01) were found in the ALS patients, indicating a vagal-sympathetic imbalance. These alterations were not related to the clinical features and to the duration of the disease. Our results suggest a subclinical involvement of the autonomic nervous system in ALS, particularly affecting parasympathetic cardiovascular control.

Adult↗
PubMed1975

Effect of autonomic neural influences on the cardiovascular changes induced by coronary occlusion.

The influence of vagal stimulation and/or beta-adrenergic receptor blockade on the heart rate, blood pressure, contractile force, and cardiac rhythm was evaluated in chloralose-anesthetized cats subjected to occlusion of the anterior descending coronary artery. Occlusion performed in 25 control animals produced significant decreases in heart rate (minus 22.9 plus or minus 4.4 beats per minute), blood pressure (minus 19.2 plus or minus 2.4 mm. Hg), and contractile force (minus 21.6 plus or minus 6.3 per cent). Death due to ventricular fibrillation occurred in five out of 25 animals. Coronary occlusion performed in the presence of vagal nerve stimulation resulted in similar decreases in blood pressure, whereas the decreases in contractile force were significantly greater than in control animals. In addition, the time to onset of the arrhythmias occurring in the vagus-stimulated group was increased. Death due to ventricular fibrillation was similar to control animals (i.e., two of seven, or 28 per cent). Blockade of beta-adrenergic receptors with propranol (0.75 mg. per kilogram) resulted in the usual decreases in rate, pressure, and force with occlusion but the duration of arrhythmias was shortened. The incidence of ventricular fibrillation was not different from that of the control animals. The combination of propranolol and vagal stimulation also failed to confer protection against ventricular fibrillation. Propranolol was observed to prevent the large decrease in contractile force seen with vagal stimulation. These results suggest that: (1) increasing vagal tone above the level existing after acute myocardial infarction does not decrease mortality, (2) propranolol pretreatment does not affect the incidence of ventricular fibrillation induced by coronary occlusion, (3) the duration of the arrhythmia after coronary occlusion is effectively shortened with propranolol, and (4) cardiac beta-adrenergic receptors do not appear to be involved in the decreases in heart rate, blood pressure, and contractile force seen with coronary occlusion.

Animals↗
PubMed1992

Effects of fentanyl-diazepam-pancuronium anesthesia on heart rate variability: a spectral analysis.

The effects of induction of anesthesia with fentanyl, 62.1 +/- 7.9 micrograms/kg, diazepam, 0.21 +/- 0.08 mg/kg, and pancuronium on beat-to-beat heart rate variations were studied in seven patients undergoing cardiac surgery. Spectral analysis was used to determine the intensity of the variations in each of the two main frequency bands in which variations are known to occur: (1) high-frequency band, mediated by the parasympathetic nervous system, at the frequency band of respiration, and (2) the low-frequency band, mediated by both sympathetic and parasympathetic nervous systems, at 0.04-0.12 Hz. Both the mean low- and high-frequency band areas were significantly decreased after induction of anesthesia. The ratio of high-to-low frequency band areas increased significantly after induction of anesthesia, from 45% to 62% (P less than 0.05). These results suggest that fentanyl-diazepam-pancuronium anesthesia decreases total autonomic nervous system activity and alters the balance between parasympathetic and sympathetic activities. Thus, spectral analysis of heart rate variations during anesthesia may provide a quantitative measure of assessing the activity of the autonomic nervous system.

Adult↗
PubMed1975

A cellular model for the simulation of activation in the ventricular myocardium.

A digital computer model of cardiac activation was used to investigate the relationship between cellular orientation and conduction and propagation of the ventricular activation wave front. The results of the simulation for a single cycle initiated in fully recovered tissue under normal and simplified pathological conditions (ischemia and infaraction) indicate (a) that the conduction velocity of the cellular action potential in ventricular cardiac tissue may be several (3-5) times greater than is normally considered to be the case, (b) that the ventricular activation wave front propagates transmurally from endocardium to epicardium despite fiber orientation parallel to these surfaces, without the need for assuming the existence of either lateral contacts between adjacent cells or fibers with a transmural orientation, (c) the wave front of activation propagates through ventricular cardiac tissue with an anisotropic phase velocity, (d) the presence of ischemia and infarction gives rise to tangential spread of activation, and (e) small subendocardial infarcts should not be considered to be electrically silent.

Action Potentials↗
PubMed1996

Is diabetic heart muscle disease related to cardiac ischemia or autonomic neuropathy?

Whether diabetic heart muscle disease is related to cardiac ischemia or autonomic neuropathy was investigated employing thallium-201 and [123I]meta-iodobenzylguanidine (MIBG) myocardial scintigraphy. Among ischemic hearts, displayed by TI201 scintigraphy, a distinctly dilated and hypokinetic left ventricle could not be detected. In autonomically denervated hearts, however, well demonstrated by MIBG imaging, distinct dysfunction was found. But, even in these hearts, interacting effects of some concomitant complications could not be excluded.

3-Iodobenzylguanidine↗
PubMed1975

Cardiac features of an unusual X-linked humeroperoneal neuromuscular disease.

To characterize an unusual, sex-linked recessive neuromuscular disease, we studied two families with 37 males who had involvement of distal leg and proximal arm muscle groups. Electromyography and muscle biopsy in five subjects showed features of both neuropathy and myopathy. Bradycardia and syncope in 15 involved subjects were associated with early death (before the age of 50 years). Electrocardiograms in 15 others showed a spectrum of atrial abnormalities that ranged from abnormal P waves to permanent atrial paralysis and from first-degree atrioventricular block to complete heart block. No patient exhibited clinical muscle disease without electrocardiographic atrial disease. Dilated, hypertrophied left ventricles with normal indexes of function were found in three cases with permanent atrial paralysis and chronic junctional bradycardia. Cardiomegaly and cardiac failure were not present in the other cases. We conclude that permanent ventricular pacing (instituted four patients) is indicated in many of these patients to prevent serious sequelae.

Adult↗
PubMed1995

Reproducibility of time and frequency domain analysis of heart rate variability in patients with chronic stable angina.

Before heart rate variability (HRV) can be used to investigate the effects of drugs or other clinical interventions in chronic stable angina, it is important to establish the stability and reproducibility of HRV indices over time. HRV analysis was performed on two consecutive 24-hour ambulatory ECG recordings in 19 patients with chronic stable angina. Time-domain analysis included average heart rate, variance, SDNN, SDANN5, ASDNN5 and PNN50. The power spectral analysis was computed using fast Fourier transformation for the total power (0.003 and 0.40 Hz), low frequency (0.04-0.15 Hz), and high frequency (0.15-0.40 Hz) bands. No statistically significant differences in the time or frequency domains were found between the two ambulatory ECG recordings. HRV indices in the time and frequency domains are consistent and reproducible in patients with chronic stable angina. Thus, cardiac autonomic tone can be evaluated using HRV analyses, and any significant changes that occur after medical therapy or other clinical interventions can be ascribed to the intervention rather than the lability of cardiac autonomic tone.

Adrenergic beta-Antagonists↗