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PubMed1992

[Doppler echocardiographic assessment of left atrial and left ventricular function during right bundle branch block].

Electrocardiographic, echocardiographic and Doppler echocardiographic studies were performed in 44 patients with coronary heart disease and complete right bundle branch block. The patients were found to have an impaired phase pattern of left ventricular systole and diastole as more prolonged length of its isometric relaxation and contraction, lower economic feasibility and efficiency of its contraction, moderate dilation and hypertrophy. Hemodynamic abnormalities in the left heart in these patients are closely correlate with the changes in the phase pattern of right ventricular systole and they turn out to be so greater as the degree of its hypertrophy is. In complete right bundle branch block, left ventricular pump dysfunction leads to decreased cardiac output and cardiac index, increased total peripheral vascular resistance, thus predisposing to impaired greater circulation.

Adult↗
PubMed2004

[Arrhythmia induction during atrial pacing with atrial floating electrodes].

Atrial pacing with floating electrodes primarily designed for single lead VDD systems has disadvantages attributable to the floatability of the electrodes. Body and breathing movements cause changes in the position of the atrial dipole that can lead to failure of atrial capture and sensing, and even alternation of the stimulated chamber. We report the induction of typical intranodal tachycardia episodes related to intermittent failure of atrial capture in a patient with an implanted single lead DDD pacing system. Such systems pose a substantial risk of potentially arrhythmogenic asynchronous pacing.

Aged↗
PubMed1991

[Evaluation of the activity of the heart conduction system with special reference to the sinoatrial node automatism in patients with mitral valve prolapse syndrome].

Electrophysiological examination of hearts were performed in 35 women and 25 men aged 18-63 years (mean age 38 years) without any concurrent heart diseases, divided into two groups: with PMVP (group I--40 subjects) and patients without this valvular anomaly (group II--20 subjects). In the patients with PMVP the examination revealed a significantly more frequent occurrence of the so-called "electrophysiological anomalies" (in 67.5%). The following appeared most frequently: sinus automatism disorders (32.5%), accessory a-v pathways (32.5%), longitudinal a-v node dissection (20%), and disorders of intracardiac conduction in segments: proximal (15%), distal (7.5%) and in both (5%). The implementation of pharmacological tests (with ajmalin, propranolol and atropine) made it possible to detect, in group with PMVP, the existence of occult conduction disturbances, particularly in distal segments of the conduction system (10%), and also to estimate exactly the character of the sinus node dysfunction (the background being in 7 patients functional, in 6 organic). During the programmed heart stimulation supraventricular dysrhythmias were evoked in 17 patients with PMVP. This is a proof that there is increased predisposition for paroxysmal supraventricular arrhythmias to occur in patients with mitral valve anomaly.

Action Potentials↗
PubMed1990

[Left ventricular function (based on two-dimensional echocardiographic data) during bicycle ergometry and transesophageal electrical stimulation of the atria in patients with hypertrophic cardiomyopathy].

The central hemodynamics was studied and compared in 20 patients with hypertrophic cardiomyopathy (HCMP) at rest, during bicycle ergometry (BEM) and transesophageal pacing of the atria (TEPA). According to the BEM readings, HCMP patients did not show any material differences from normals' reaction to exercise on the part of the volumetric and hemodynamic parameters as well as left ventricle contractile function. At the same time as revealed by TEPA, HCMP patients did manifest differences from normals' response in the hemodynamics and myocardial contractility. Alterations that occur in HCMP patients undergoing TEPA in response to an isolated increase of frequency of the cardiac rhythm are likely to reflect latent disorders of systolic function of the asymmetric hypertrophied left ventricle which is not capable of making adequate volumetric and functional restructure.

Adult↗
PubMed1995

P-pulmonale.

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Atrial Function, Left↗
PubMed1994

Effects of intravenous anaesthetics on function and metabolism in the isolated rat heart-lung preparation.

The influence of several intravenous anaesthetics on the heart was assessed using the isolated rat heart-lung preparation. Each group received 10(-3)mol litre-1 and 10(-4)mol liter-1 of ketamine, 6 micrograms ml-1 and 60 micrograms ml-1 of midazolam, 6 micrograms ml-1 and 60 micrograms ml-1 of diazepam or 0.6 micrograms ml-1 and 6 micrograms ml-1 of flunitrazepam. Systolic blood pressure in rats receiving high doses of midazolam, diazepam and ketamine were higher than that in the control group. Heart rate in rats receiving high doses of ketamine and diazepam were lower than that in the control group. However, there were no significant changes in cardiac output among the groups. Maximum rate of left ventricular tension development in rats receiving high doses of midazolam and diazepam increased significantly in comparison with that in the control group. There were no significant changes in myocardial high energy phosphates among the groups. None of the intravenous anaesthetics, even in doses which were 100 times greater than therapeutic doses, showed any depressant effects in this preparation. Moreover, it is surprising that midazolam and diazepam produced direct increases in myocardial contractility. These results suggest that the cardiodepressant effects of intravenous anaesthetics may be due to their effects on the central nervous system.

Adenosine Diphosphate↗
PubMedDate not supplied

Posttransplantation hemodynamics and exercise function are not affected by body-size matching of donor and recipient.

Because the number of heart transplantations performed is limited by the number of available donor hearts, many centers have expanded the acceptable criteria for donor hearts in an attempt to provide a sufficient number of donors for the number of patients awaiting heart transplantation. Traditionally, body-size matching has been an important criteria for matching donors with potential heart transplant recipients. Although initially thought to be detrimental, studies have shown no difference in survival of patients who receive hearts from smaller donors, but heart performance in this subset of patients who receive undersized hearts has not been extensively examined. We assessed exercise capacity and 1-year posttransplantation hemodynamics in 72 consecutive adult orthotopic heart transplant recipients, grouped according to donor-recipient weight ratio and the ratio of donor to recipient body surface area. Total exercise time and relative oxygen consumption were not significantly different among three groups of patients grouped according to donor-recipient body weight ratio as follows: low, 0.60 to 0.79; mid, 0.80 to 1.0; high, more than 1.0. No difference was noted among the three donor-recipient weight ratio groups with respect to 1-year posttransplantation hemodynamics. Similarly, 1-year posttransplantation hemodynamics were not different between patients with a body surface area ratio of less than 1.0 versus those with a body surface area ratio of 1.0 or more. Differences in pretransplantation hemodynamics or graft preservation did not affect our results. Neither donor-recipient weight ratio nor body surface area ratio correlated with any posttransplantation hemodynamic measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The effect of reversal of myoneural blockade on cerebrospinal fluid pressure following cerebral aneurysm surgery.

Drugs with a depolarizing action at the myoneural junction may cause a rise in intracranial pressure. Neostigmine, which is commonly used to reverse residual myoneural blockade, has a depolarizing action, and yet its effect on intracranial pressure is unknown. Lumbar cerebrospinal fluid pressure, which mirrors intracranial pressure, was determined in 12 patients undergoing cerebral aneurysm surgery. Cerebrospinal fluid pressure was measured during dense myoneural blockade and after its reversal with neostigmine. These effects on cerebrospinal fluid pressure were compared with those produced when the arterial partial pressure of carbon dioxide (PaCO2) rose from 4 to 5 kPa. After reversal of myoneural block, there was a small (non-significant) change in cerebrospinal fluid pressure from 3.6 to 4.3 kPa and a larger (significant) rise in cerebrospinal fluid pressure to 9.7 kPa when the PaCO2 was allowed to rise. In this group of patients, reversal of myoneural blockade with neostigmine causes no significant change in cerebrospinal fluid pressure.

Adult↗
PubMed1995

[Atrial filling fraction predicts left ventricular systolic function after myocardial infarction: pre-discharge echocardiographic evaluation].

Aim of the study was to examine the relation between Doppler-derived indices of left ventricular diastolic and systolic function early after myocardial infarction. Fifty-three patients (31 males, 22 females) recovering from acute myocardial infarction underwent predischarge Doppler echocardiographic examination. Patients with age > 70 years, previous myocardial infarction, more than mild mitral and aortic regurgitation, mitral and aortic stenosis were excluded. Twenty-two healthy subjects (13 males; 9 females) free of coronary risk factors were selected as the control group. Both end-diastolic and end-systolic volumes and ejection fraction were measured by two-dimensional echocardiography. Pulsed Doppler was used to evaluate mitral inflow and left ventricular outflow velocity patterns. The following indices were measured: peak velocity of early (E) and late (A) flows, ratio of E/A peak velocities, ratio of early to late time velocity integrals, atrial filling fraction (time velocity integral A / time velocity integral of flow during total diastole) and deceleration time of E wave for mitral inflow; peak and time-velocity integral for left ventricular outflow. Stroke volume and cardiac output were obtained by pulsed Doppler using the left ventricular outflow method. The two groups were comparable for age, with blood pressure (p < 0.05) and heart rate (p < 0.01) reduced in myocardial infarction patients. Both end-diastolic and end-systolic volumes were significantly higher (both p < 0.0001) and ejection fraction (p < 0.0001) lower after myocardial infarction. Also stroke volume and cardiac output (both p < 0.0001) were reduced in myocardial infarction patients. No significant difference in Doppler indices of diastolic function was observed between the two groups, except for shortened deceleration time (p < 0.0001) in myocardial infarction patients. Multilinear regression analyses were performed separately into the two groups to identify determinants of left ventricular systolic function. After adjusting for age, heart rate, systolic blood pressure and both end-diastolic and end-systolic volumes, atrial filling fraction was an independent predictor of stroke volume, with a direct relation (beta coefficient = 0.53, p < 0.001), in myocardial infarction patients but not in health subjects. In conclusion, our study confirms the pseudonormalization of diastolic pattern after myocardial infarction. The direct relation between atrial filling fraction and stroke volume indicates the importance of atrial contribution to maintain an adequate systolic performance in patients with myocardial infarction.

Atrial Function, Right↗
PubMed1998

Cardiorespiratory effects of sevoflurane, isoflurane, and halothane anesthesia in horses.

OBJECTIVE: To determine and compare cardiorespiratory and recovery effects of sevoflurane, isoflurane, and halothane in horses. ANIMALS: 8 clinically normal horses (4 mares, 4 geldings), 5 to 12 years old. PROCEDURE: Inhalation anesthesia was maintained for 90 minutes with sevoflurane, isoflurane, or halothane. Anesthesia depth was maintained at 1.5 minimum alveolar concentration of halothane, isoflurane, and sevoflurane, then was reduced at 30 and 60 minutes. A surgical plane of anesthesia was reinduced by administration of ketamine or thiopental or by increasing the fractional inspired concentration of sevoflurane. Cardiovascular and pulmonary variables were recorded and compared among inhalation anesthetics. Recovery was monitored, and subjective assessment of recovery quality was performed. RESULTS: Hemodynamic and pulmonary indices during sevoflurane anesthesia were similar to those of isoflurane. Cardiac output and systemic arterial pressure decreased less during sevoflurane and isoflurane anesthesia than during halothane anesthesia. After 90 minutes, cardiac output was greater for sevoflurane and isoflurane, respectively, compared with halothane. Mean arterial pressure was similar for all three anesthetic agents. Respiratory rate for sevoflurane and isoflurane was less than that for halothane. This apparent respiratory depression correlated with greater increase in PaCO2 and decreased pH when sevoflurane and isoflurane were compared with halothane. Recovery from sevoflurane anesthesia was qualitatively similar and superior to recovery from isoflurane and halothane, respectively. Time to standing did not differ significantly between sevoflurane and isoflurane, but was shorter than halothane. CONCLUSIONS: Sevoflurane induced cardiorespiratory effects that were comparable to those of isoflurane and halothane. Cardiac output was greater and respiratory rate was less than that for halothane at 1.5 MAC. Sevoflurane anesthesia was characterized by good control of anesthesia depth during induction, maintenance, and recovery. Recovery time after sevoflurane anesthesia was comparable to that for isoflurane, and recovery was smooth and controlled in a manner consistent with recovery from halothane.

Anesthesia, Inhalation↗
PubMedDate not supplied

[Persistent atrial paralysis: reported of 2 cases].

Persistent atrial standstill is an uncommon clinical finding, this condition has no atrial electrical activity and do not respond to electrical stimulation. Electrophysiologic mapping of the heart, demonstrates two types of standstill: total and partial. There are three types of patients with this condition: patients with chronic cardiopathy, patients with muscular dystrophy and the third idiopathic group. In this article, we present two clinical cases, the fist one with dilated cardiomiopathy, in which we demonstrated total atrial standstill. The second patient with rheumatic heart disease, in which we demonstrated partial standstill that included the apical portion of the rigth atrium. We discuss the clinical and electrophysiological finding of both cases and we review the literature.

Adult↗
PubMed1980

Extreme right ventricular hypoplasia after relief of severe pulmonary stenosis. Use of balloon catheter occlusion of atrial septal defect in assessing right ventricular function.

A patient is described in whom extreme right ventricular hypoplasia and right-to-left shunting through an atrial septal defect occurred after relief of severe pulmonary stenosis. The ability of the hypoplastic right ventricle to deal with an increased volume load was assessed at cardiac catheterisation by occluding the atrial septal defect with a balloon tipped catheter.

Adult↗
PubMed1994

Mapping the conversion of atrial flutter to atrial fibrillation and atrial fibrillation to atrial flutter. Insights into mechanisms.

It is not generally believed that there is a relation between atrial flutter, thought to be due to a single reentrant circuit, and atrial fibrillation, thought to be due to simultaneously circulating multiple-reentrant wave fronts. However, there are many reasons to suggest that these rhythms are more closely related than previously thought. To test the hypothesis that the length of an area of functional block in the right atrial free wall is critical to the conversion of atrial flutter to atrial fibrillation and of atrial fibrillation to atrial flutter, we studied spontaneous and ATP-induced conversion of stable atrial flutter to sustained atrial fibrillation and spontaneous conversion of sustained atrial fibrillation to stable atrial flutter. We studied 13 episodes of the conversion of stable atrial flutter to sustained atrial fibrillation and sustained atrial fibrillation to stable atrial flutter in seven dogs with sterile pericarditis. Six episodes were spontaneous and seven were ATP related. All episodes were studied by using a multisite mapping system to record 190 unipolar electrograms (converted in the software to 95 bipolar electrograms) from the right atrial free wall along with ECG lead II. Atrial flutter induction was attempted by atrial stimulation (S1S2 or S1S2S3) or by rapid atrial pacing for > or = 20 beats from selected sites at selected rates. For both the spontaneous and the ATP-related episodes, stable atrial flutter was defined as any episode of > or = 5 minutes, and sustained atrial fibrillation was any episode of > or = 1 minute. During all the episodes of stable atrial flutter, a line of functional block with a mean length of 24 +/- 4 mm was localized on the right atrial free wall. When the previously stable line of functional block decreased to a mean of 16 +/- 3 mm (P < .05), either spontaneously or after ATP administration (40 mg i.v.), the new line of functional block was not long enough to maintain stable atrial flutter, and conversion to atrial fibrillation resulted. This shortened line of functional block continued to change and migrate over the right atrial free wall throughout sustained atrial fibrillation. These observations were similar for both spontaneous and ATP-induced conversions. When sustained atrial fibrillation evolved to stable atrial flutter, there was reformation of a long line of functional block, long enough (> or = prior length) to create a stable reentrant circuit, which then captured the right atrial free wall and subsequently both atria.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed2003

Interactions within the intrinsic cardiac nervous system contribute to chronotropic regulation.

The objective of this study was to determine how neurons within the right atrial ganglionated plexus (RAGP) and posterior atrial ganglionated plexus (PAGP) interact to modulate right atrial chronotropic, dromotropic, and inotropic function, particularly with respect to their extracardiac vagal and sympathetic efferent neuronal inputs. Surgical ablation of the PAGP (PAGPx) attenuated vagally mediated bradycardia by 26%; it reduced heart rate slowing evoked by vagal stimulation superimposed on sympathetically mediated tachycardia by 36%. RAGP ablation (RAGPx) eliminated vagally mediated bradycardia, while retaining the vagally induced suppression of sympathetic-mediated tachycardia (-83%). After combined RAGPx and PAGPx, vagal stimulation still reduced sympathetic-mediated tachycardia (-47%). After RAGPx alone and after PAGPx alone, stimulation of the vagi still produced negative dromotropic effects, although these changes were attenuated compared with the intact state. Negative dromotropic responses to vagal stimulation were further attenuated after combined ablation, but parasympathetic inhibition of atrioventricular nodal conduction was still demonstrable in most animals. Finally, neither RAGPx nor PAGPx altered autonomic regulation of right atrial inotropic function. These data indicate that multiple aggregates of neurons within the intrinsic cardiac nervous system are involved in sinoatrial nodal regulation. Whereas parasympathetic efferent neurons regulating the right atrium, including the sinoatrial node, are primarily located within the RAGP, prejunctional parasympathetic-sympathetic interactions regulating right atrial function also involve neurons within the PAGP.

Animals↗
PubMed2005

Analysis of atrial and ventricular performance by tissue Doppler imaging in patients with atrial septal defects before and after surgical and catheter closure.

OBJECTIVE: To compare the effects of surgical and device closure of atrial septal defects on atrial and ventricular performance assessed by the novel tissue Doppler derived strain rate. BACKGROUND: Despite the increasing number of transcatheter closures, there is no information comparing the effect of the transcatheter closure technique on atrial performance with that of conventional surgery. Tissue Doppler derived strain rate can effectively quantify local myocardial function independent of the overall heart motion. DESIGN AND PATIENTS: Twenty-four patients [aged 21.5 (6-70) years] with isolated atrial septal defect of the secondum type before and 1 week after surgical (n = 12) or Amplatzer Septal Occluder closure (n = 12) and 30 healthy controls [aged 26.0 (2-58) years] were studied. Atrial and ventricular strain rate curves were assessed in the middle of their corresponding lateral walls in an apical four-chamber view. The systolic, early diastolic, and late diastolic strain rates peaks were measured. RESULTS: Compared to preclosure condition, the right atrial late diastolic (P < 0.01), right ventricular systolic (P < 0.01), right ventricular early diastolic (P < 0.01), and left atrial late diastolic peak (P < 0.01) strain rates were reduced after surgery but not after Amplatzer Septal Occluder closure. The LV parameters did not significantly differ before and after atrial septal defect closure by either technique. CONCLUSIONS: In contrast to surgery, transcatheter closure of atrial septal defect preserves atrial and right ventricular function. Tissue Doppler derived strain rate can be applied to provide quantitative analysis of regional atrial and ventricular performance.

Adolescent↗