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At least 1,315 records · Page 73Linked to original sources
PubMed1999

Sevoflurane has no effect on sinoatrial node function or on normal atrioventricular and accessory pathway conduction in Wolff-Parkinson-White syndrome during alfentanil/midazolam anesthesia.

BACKGROUND: The effects of sevoflurane on the electrophysiologic properties of the human heart are unknown. This study evaluated the effects of sevoflurane on the electrophysiologic properties of the normal atrioventricular conduction system, and on the accessory pathways in patients with Wolff-Parkinson-White syndrome, to determine its suitability as an anesthetic agent for patients undergoing ablative procedures. METHODS: Fifteen patients with Wolff-Parkinson-White syndrome undergoing elective radiofrequency catheter ablation were studied. Anesthesia was induced with alfentanil (20-50 microg/kg) and midazolam (0.15 mg/kg), and vecuronium (20 mg) and maintained with alfentanil (0.5 to 2 microg x kg(-1) x min(-1)) and midazolam (1 or 2 mg every 10-15 min, as required). An electrophysiologic study measured the effective refractory period of the right atrium, atrioventricular node, and accessory pathway; the shortest conducted cycle length of the atrioventricular node and accessory pathway during atrial pacing; the effective refractory period of the right ventricle and accessory pathway; and the shortest retrograde conducted cycle length of the accessory pathway during ventricular pacing. Parameters of sinoatrial node function included sinus node recovery time, corrected sinus node recovery time, and sinoatrial conduction time. Intraatrial conduction time and the atrial-His interval were also measured. Characteristics of induced reciprocating tachycardia, including cycle length, atrial-His, His-ventricular, and ventriculoatrial intervals, also were measured. Sevoflurane was administered to achieve an end-tidal concentration of 2% (1 minimum alveolar concentration), and the study measurements were repeated. RESULTS: Sevoflurane had no effect on the electrophysiologic parameters of conduction in the normal atrioventricular conduction system or accessory pathway, or during reciprocating tachycardia. However, sevoflurane caused a statistically significant reduction in the sinoatrial conduction time and atrial-His interval but these changes were not clinically important. All accessory pathways were successfully identified and ablated. CONCLUSIONS: Sevoflurane had no effect on the electrophysiologic nature of the normal atrioventricular or accessory pathway and no clinically important effect on sinoatrial node activity. It is therefore a suitable anesthetic agent for patients undergoing ablative procedures.

Adult↗
PubMed2002

Enalapril effects on atrial remodeling and atrial fibrillation in experimental congestive heart failure.

OBJECTIVE: Atrial remodeling contributes to the maintenance of atrial fibrillation (AF) in several cardiac disorders. There is evidence that angiotensin-converting enzyme (ACE) inhibitors reduce the prevalence of AF in patients with congestive heart failure (CHF). There have been no studies performed to assess the effects of ACE inhibitors on atrial dimensions and emptying function in relationship to vulnerability to AF in the setting of experimental CHF. METHODS: CHF was produced in 20 dogs by rapid right ventricular pacing during 5 weeks. The dogs were randomized to enalapril (EN) therapy (2 mg/kg/day, n=10) or to a control group (n=10). Echocardiography was performed at baseline and weekly thereafter. At the 5-week electrophysiological study, AF was induced by burst pacing and AF duration was measured. RESULTS: Atrial areas increased significantly with CHF. Left atrial (LA) fractional area shortening (FAS) decreased by 42% (P=0.0001) in controls but by 9% (P=NS) in the EN group (P=0.01, EN vs. controls). Similar findings were observed for right atrial (RA) changes (P=0.02). Atrial fibrosis was highly correlated with the decrease in LA FAS (r=0.85, P<0.01) and was reduced by EN (from 11.2+/-1.6 to 8.3+/-0.7%, P=0.008). AF duration was 720+/-461 s for controls and 138+/-83 s for EN (P=0.001). LA and RA areas and FAS at 5 weeks correlated with AF duration (P< or =0.001 for all). FAS decrease in both atria also correlated with AF duration at follow-up (r=0.78 and 0.77 for LA and RA, P< or =0.001 for both). CONCLUSIONS: Experimental CHF causes structural and functional abnormalities in both atria, which are correlated with AF duration. ACE inhibition attenuates CHF-induced atrial fibrosis and remodeling and reduces associated AF promotion. These results indicate a role for the renin-angiotensin system in arrhythmogenic atrial structural remodeling in CHF.

Action Potentials↗
PubMed1993

Exercise-induced upward shift of diastolic left ventricular pressure-volume relation in patients with dilated cardiomyopathy. Effects of beta-adrenoceptor blockade.

BACKGROUND: The effectiveness of beta-blocker therapy for dilated cardiomyopathy (DCM) may be attributed to the inhibition of detrimental effects on the failing heart of sympathetic stimulation during exertion. However, the harmful effects of activity as well as the protective effects of beta-blockers have not been demonstrated. Diastolic ventricular function is known to be sensitive to transient myocardial metabolic insult. In this study, we investigated the effect of modest exercise with or without beta-blockade on the diastolic left ventricular pressure-volume (P-V) relation in patients with DCM. METHODS AND RESULTS: The diastolic left ventricular P-V relation was obtained by high-fidelity pressure measurements and digital subtraction left ventriculography at rest and immediately after modest supine bicycle exercise in 12 patients with DCM. The effects of intravenous administration of 0.1 mg/kg propranolol on resting and exercise P-V relations were studied. The end-diastolic and lowest left ventricular pressures were significantly elevated by exercise (20 +/- 9 to 32 +/- 13 mm Hg, P < .01, and 12 +/- 6 to 21 +/- 11 mm Hg, P < .01, respectively) despite insignificant changes in left ventricular volumes. The administration of propranolol did not alter the resting diastolic P-V relation. However, propranolol significantly attenuated the exercise-induced upward shift of the diastolic P-V relation despite a significant increase in end-diastolic volume. The significant upward shift and attenuation by propranolol were also observed even when the left ventricular pressure was corrected by the subtraction of right atrial pressure. CONCLUSIONS: These results indicate that even modest exercise exerts detrimental effects on diastolic left ventricular function of the failing heart through beta-adrenergic stimulation. The clinical effectiveness of beta-blocker therapy in patients with DCM can be attributed in part to the inhibition of detrimental myocardial effects of sympathetic stimulation during daily activity.

Adrenergic beta-Antagonists↗
PubMed1983

[Chrono- and inotropic and heterometric regulation of mechanical activity in the heart of atrial fibrillation patients].

The theory of accidental functions was used in the analysis of the heart's mechanical activity. The dependence of right-ventricular pressure on R--R duration and ultimate diastolic pressure was evaluated in 10 patients, using cardiac probe. Cross-correlation and cross-variance functions were used to assess chrono-inotropic relationship and the relationship between ultimate diastolic and systolic pressure values. Poor correlation was shown between ultimate diastolic and systolic pressure in tachycardia. Evidence is presented that mechanical activity is controlled through chrono-inotropic relationship in tachysystolic arrhythmias. In cases of normosystole and bradycardia, the heterometric system makes the principal contribution to the control of the heart mechanical activity.

Adult↗
PubMedDate not supplied

[Phonomechanocardiographic analysis in patients with artifical pacemaker].

Eighteen patients with artificial pacemakers have been studied by phonomecanocardiographic means. All had complete atrio-ventricular block. Ten had an endocardial electrode in the right ventricle and 10 an epicardial in the free wall of the left ventricle. Two patients were studied, first with a temporal endocardial pacemaker and then with a permanent one. The studies were divided in 3 groups: Group I. In six cases comparison was made between the systolic tunes of the normally conducted cycles, and the ones produced by direct ventricular stimulations. The beats produced by direct ventricular stimulation showed a statistically significant diminution of the function of the left ventricle. This was reflected by a shorter relative ejection period. This diminution can possibly be explained by one of two mechanisms: absence of the "atrial kick", or alteration in the sequence of depolarization and ventricular contraction, producing an asynchrony in the contraction. This would lead us to suppose that the best site for contact of the electrode would be the middle third of the left aspect of the ventricular septum, where the activation starts normally. Group II. Ventricular function was compared in 20 cases, depending on the site of electrical stimulation: endocardium of right ventricle or epicardium of the left ventricle: there were no statistically significant differences. Group III. On 14 cases we studied cycles in which an effective contribution of the atrial kick could be expected, because the interval between the P wave and the electrical artifact was less than 300 msec. These were compared with others with a larger, statistically significant, improvement of the left ventricular function it was observed as a longer ejection period in the cases with a P wave-electrical artifact pause shorter than 300 msec.

Adolescent↗
PubMedDate not supplied

Pulmonary atresia with intact ventricular septum associated with congenitally corrected transposition.

We present a rare case of pulmonary atresia with intact septum associated with congenitally corrected transposition. The patient was a nondysmorphic female infant. Despite a right Blalock-Taussig shunt on day 13 of life and a balloon atrial septostomy on day 23, she remained ventilator dependent with poor systemic ventricular function. The patient died at the age of 160 days, and postmortem findings are presented. The literature on this condition is reviewed, and the possibility that the left-sided morphologic right ventricle could not sustain the systemic circulation is discussed.

Abnormalities, Multiple↗
PubMed1993

[Successful two-staged Jatene operation for severe right ventricular dysfunction and tricuspid regurgitation after Senning operation--a case report].

We report a seven-year-old boy who underwent a successful Jatene procedure seven years after Senning procedure. The modified Senning operation was performed for the treatment of transposition of the great arteries with intact ventricular septum at three years of age. However, he gradually showed the progressive right ventricular failure with tricuspid regurgitation after operation. When he was referred to our hospital, he was in severe right ventricular failure and showed massive tricuspid regurgitation simultaneously with the moderate degree of left ventricular failure. Staged pulmonary artery banding was applied to prepare the left ventricle for Jatene procedure in spite of the presence of left ventricular failure. The systolic pressure ratio of left ventricle to right ventricle was elevated to 0.91 by this banding although the left ventricular ejection fraction decreased from 43% to 30%. And Jatene procedure was successfully performed after three months of preparation period. Catheterization study after Jatene procedure revealed improved right and left ventricular functions with decrease of tricuspid regurgitation. We conclude that the Jatene procedure should be an ideal alternative in patient with right ventricular failure and/or tricuspid regurgitation after an atrial switch operation; the left ventricle could be prepared by an effective pulmonary banding in most instances.

Child↗
PubMed2004

[Dynamics of parameters of diastole and subendocardial right ventricular blood flow in adult patients after correction of atrial septal defect].

The study of intracardiac hemodynamics and subendocardial blood flow in 55 adults with atrial septal defect confirmed practical value of assessment of myocardial contractility by long term catheterization of right cardiac chambers, construction of right ventricular function curves and "pressure-volume" diagrams. Simultaneous graphical registration with the help of computer diagnostic system represented character and direction of changes of controlled parameters during the period of observation as well as peculiarities of interventricular interaction after removal of isotonic right ventricular overload. Compared with traditional hemodynamic monitoring this approach to analysis of intracardiac hemodynamics provided real time assessment of cardiac function, facilitated elucidation of causes of cardiac output lowering and optimization of myocardial contractility regulation.

Adult↗
PubMed1996

Effects of failure of the right side of the heart and increased pulmonary resistance on mechanical circulatory support with use of the miniaturized HIA-VAD displacement pump system.

This experimental study was designed to assess the influence of failure of the right side of the heart or pulmonary hypertension, or both, on the performance of a novel miniaturized left ventricular assist device. In small-sized dogs (n = 50) ischemic global left ventricular failure was induced and support was provided by the HIA-VAD displacement pump (stroke volume 10 or 25 ml) installed as a left ventricular assist device. In three groups of animals (n = 10 each) pulmonary hypertension was created before induction of global left ventricular failure. During left ventricular assist device support temporary ischemic failure of the right side of the heart was induced in four groups of animals (n = 10 each). In the group subjected to left ventricular failure, support with the left ventricular assist device, and right ventricular failure during left ventricular assist, left atrial pressure and cardiac index were significantly lower than in the group subjected to left ventricular failure and left ventricular assist alone (2 +/- 6 versus 11 +/- 6 mm Hg and 1.6 +/- 0.4 versus 1.0 +/- 0.4 L/(min/m2), respectively, p < 0.05). In the group subjected to pulmonary hypertension, left ventricular failure, and left ventricular support, left atrial pressure dropped to values near zero but cardiac index remained unaltered as compared with results with the same regimen without pulmonary hypertension. However, when right ventricular failure was added (that is, pulmonary hypertension, left ventricular failure, left ventricular support, and right ventricular failure during support with the left ventricular assist device) left atrial pressure dropped to negative values (p < 0.05) and cardiac index progressively deteriorated. When, in an additional group of dogs, biventricular support was installed in the latter regimen, circulation was initially well supported but oxygenation deteriorated in 60% of cases. We conclude that (1) adequate right ventricular function was indispensable during support with the left ventricular assist device, (2) the combination of pulmonary hypertension and right ventricular failure led to the "low left ventricular assist device output syndrome," and (3) biventricular mechanical support in the presence of pulmonary hypertension may be complicated by the alveolar leakage syndrome.

Animals↗
PubMed2000

Idiopathic annular dilation: a rare cause of isolated severe tricuspid regurgitation.

The management of patients with severe tricuspid regurgitation (TR) requires the clinician to clarify the mechanism of regurgitation. Primary disorders of the tricuspid valve, either congenital or acquired, may be readily identified by echocardiography. Severe TR most often results from left-sided heart disease and secondary pulmonary hypertension. Cardiomyopathic processes may also cause right ventricular failure and functional TR. We report three patients with severe TR due to idiopathic annular dilation. The tricuspid valves were otherwise normal on surgical inspection, and the pulmonary pressures were not significantly elevated. Each patient was aged over 65 years and had chronic atrial fibrillation with preserved left ventricular systolic function. Surgical treatment was associated with marked clinical improvement. Clinicians should recognize this unusual but treatable cause of right-sided congestive heart failure.

Aged↗
PubMed1995

Circulating concentrations and physiologic role of atrial natriuretic peptide during endotoxic shock in the rat.

OBJECTIVES: To determine if there are changes in circulating concentrations of endogenous atrial natriuretic peptide and the physiologic role of this peptide in endotoxic shock. DESIGN: A prospective, randomized, controlled animal trial. SETTING: University research laboratory. SUBJECTS: Anesthetized male Wistar rats, weighing 250 to 350 g. INTERVENTIONS: Six rats received 1.5 mg/kg body weight of lipopolysaccharide alone. Five rats received 1.5 mg/kg of lipopolysaccharide and 200 microL/100 g body weight of rabbit anti-atrial natriuretic peptide serum. Another five rats received 1.5 mg/kg of lipopolysaccharide and normal rabbit serum in the same volume as the antiserum. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of atrial natriuretic peptide, arginine vasopressin, and aldosterone were measured, and changes in hemodynamic parameters and renal function were monitored in rats with endotoxic shock after catheterization of the right jugular vein. Urine volume, urine sodium excretion, urinary potassium excretion, and urine 3', 5'-cyclic guanosine monophosphate (cGMP) excretion were measured at 12-hr intervals. The plasma atrial natriuretic peptide concentration was slightly but significantly lower 30 mins after the lipopolysaccharide injection (114.8 +/- 9.0 pg/mL at 0 hr, 75.6 +/- 6.2 pg/mL at 30 mins, p < .01) and then began to increase, peaking at 6 hrs (752.8 +/- 104.5 pg/mL, p < .01 vs. 0 time) and remaining at higher concentrations than before the preinjection value, up to 24 hrs. In contrast, acute spike-like increases of arginine vasopressin and aldosterone concentrations were observed 30 mins after the lipopolysaccharide injection, preceding the increase of the plasma atrial natriuretic peptide concentration. Measurements of urine volume and urine sodium excretion showed oliguria during the initial 12 hrs after the lipopolysaccharide injection, followed by diuresis and natriuresis during the subsequent 12 hrs. In addition, injection with anti-atrial natriuretic peptide serum in the diuretic phase 12 hrs after the lipopolysaccharide injection significantly inhibited the diuresis, natriuresis, and urine cGMP excretion in this model. Furthermore, the plasma aldosterone concentration 24 hrs after the lipopolysaccharide injection was significantly increased by the administration of the antisera. CONCLUSIONS: These findings suggest that endogenous atrial natriuretic peptide increases in the acute phase of endotoxic shock and plays an important role in water and electrolyte balance by regulating diuresis.

Aldosterone↗
PubMed1996

Value of perioperative Doppler echocardiography in patients undergoing major lung resection.

BACKGROUND: The effects of major lung resection on right heart function have not been well established. Our goal was to evaluate these effects using serial Doppler echocardiography in the perioperative period. METHODS: In 86 patients undergoing lobectomy (n = 47) and pneumonectomy (n = 39), we examined the effects of pulmonary resection on perioperative changes in right heart function by transthoracic echocardiography. Serial echocardiograms were performed preoperatively, on postoperative day 1, and again between postoperative days 2 and 6 (median, 3 days) to evaluate cardiovascular function and to estimate right ventricular systolic pressure by the tricuspid regurgitation jet Doppler velocity method. RESULTS: Right or left atrial size, right atrial pressure, and estimated right ventricular systolic pressure did not differ between groups on the preoperative or postoperative day 1 examinations. However, on postoperative days 2 through 6 patients who underwent pneumonectomy had higher (mean +/- standard deviation) right ventricular systolic pressure values than lobectomy patients (31 +/- 15 versus 25 +/- 10 mm Hg, respectively; p < 0.05 by analysis of variance). In the subset of patients with percent predicted forced expiratory volume in 1 second less than 60% undergoing pneumonectomy (9/39), preoperative right ventricular systolic pressure was inversely correlated with percent predicted forced expiratory volume in 1 second values (r = -0.78; p < 0.04). This correlation was not significant in corresponding lobectomy patients. Postoperative right ventricular enlargement determined by echocardiography occurred with similar frequency in both groups and was associated with poor short-term prognosis in patients in whom severe respiratory failure developed. CONCLUSIONS: Preoperative indices of right heart function were within the normal range in both groups. Pneumonectomy but not lobectomy was associated with mild postoperative pulmonary hypertension that was not accompanied by significant right ventricular systolic dysfunction. Postoperative echocardiography may be useful to evaluate right heart function in critically ill patients after lung resection.

Adult↗
PubMed1985

Electrophysiologic effects of flecainide acetate and its major metabolites in the canine heart.

Flecainide acetate, an investigational class 1 antiarrhythmic agent, undergoes biotransformation in man with production of 2 major metabolites: meta-O-dealkylated flecainide (S-24623) and the meta-O-dealkylated lactam of flecainide (S-26191). This study compared the effects of flecainide, S-24623 and S-26191 on cardiac electrophysiologic characteristics in the anesthetized dog. Each dog received 2 dose levels of 1 of the 3 test compounds after control measurements. Flecainide (2 and 4 mg/kg in 8 dogs), S-24623 (4 and 8 mg/kg in 8 dogs) and S-26191 (4 and 10 mg/kg in 7 dogs) were administered intravenously in dilute solution. Of the 3 compounds, only flecainide significantly prolonged sinus cycle length (p less than 0.01). However, both flecainide and S-24623 significantly prolonged minimum atrial paced cycle length with 1:1 atrioventricular conduction, atrioventricular nodal effective and functional refractory periods, and right ventricular effective refractory period. Metabolite S-26191 exhibited qualitatively similar but much weaker electrophysiologic actions. The maximal electrophysiologic effects of flecainide and S-24623 were approximately equivalent, but the metabolite was about one-half as potent on a milligram-permilligram basis, and lacked marked effects on infranodal (HV interval) conduction. S-26191 was less than one-tenth as potent as flecainide. Therefore, since both flecainide metabolites occur primarily in the conjugated form in plasma (i.e., free metabolite concentrations are low), it is unlikely that these compounds either potentiate flecainide's antiarrhythmic action or increase susceptibility to drug toxicity in the clinical setting.

Animals↗
PubMed1991

Clinical, radiographic, and hemodynamic correlations in chronic congestive heart failure: conflicting results may lead to inappropriate care.

PURPOSE: Clinical and radiographic examinations are commonly used for estimating severity and titrating therapy of chronic congestive heart failure. The purpose of this study was to establish the relationship between findings on history, physical examination, chest roentgenogram, and pulmonary capillary wedge pressure (PCWP). PATIENTS AND METHODS: Fifty-two consecutive patients with chronic congestive heart failure, referred for evaluation for heart transplantation, were studied; all patients underwent history, physical examination, upright chest roentgenogram, and cardiac catheterization. The mean left ventricular ejection fraction was 0.19 +/- 0.06. Patients were divided into three groups according to their PCWP: Group 1, normal PCWP (less than or equal to 15 mm Hg, n = 19); Group 2, mild to moderately elevated PCWP (16 to 29 mm Hg, n = 15); Group 3, markedly elevated PCWP (greater than or equal to 30 mm Hg, n = 18). RESULTS: Physical and radiographic signs of congestion were more common in the groups with higher PCWP, but they could not be used to reliably separate patients with different filling pressures. Physical findings (orthopnea, edema, rales, third heart sound, elevated jugular venous pressure) or radiographic signs (cardiomegaly, vascular redistribution, and interstitial and alveolar edema) had poor predictive value for identifying patients with PCWP values greater than or equal to 30 mm Hg. These findings had poor negative predictive value to exclude significantly elevated PCWP (greater than 20 mm Hg). Radiographic pulmonary congestion was absent in eight (53%) patients in Group 2 and seven (39%) in Group 3. In patients in Group 2 and 3, those without radiographic congestion were in a better New York Heart Association functional class (3.5 +/- 0.5 versus 2.8 +/- 0.6, p less than 0.01). There was good correlation between right atrial pressure and PCWP (r = 0.64, p less than 0.001). A normal right atrial pressure had no predictive value, but a pressure greater than 10 mm Hg was seen in all but one patient with a PCWP value greater than 20 mm Hg. CONCLUSION: Clinical, radiographic, and hemodynamic evaluations of chronic congestive heart failure yield conflicting results. Absence of radiographic or physical signs of congestion does not ensure normal PCWP values and may lead to inaccurate diagnosis and inadequate therapy. It is not known whether therapy aimed at normalizing PCWP is superior to relieving clinical and radiographic signs of congestion.

Adult↗