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PubMed1985

The beneficial effect of amrinone on acute drug-induced heart failure in the anaesthetised dog.

Amrinone, a positive inotropic-vasodilator agent, was administered to anaesthetised dogs in an attempt to reverse heart failure induced by drugs possessing negative inotropic properties. Propranolol, a beta-adrenergic blocker; verapamil, a calcium slow-channel blocker procainamide, a type 1 antiarrhythmic agent; or sodium pentobarbital, a barbituate; administered as a bolus injection and/or infusion, produced a sustained depression in canine cardiac function. Cardiac depression was characterised by a greater than 40% reduction in cardiac contractile force (CF) and maximum left ventricular pressure development (LV dp/dtmax), a 30 to 50% reduction in cardiac output (CO) and concomitant increases in mean central venous or mean right atrial blood pressures (CVP, RAP, respectively). Amrinone, when administered intravenously as a bolus injection (1 or 3 mg X kg-1) plus an infusion (0.03 or 0.1 mg X kg-1 X min-1) reversed the depression in cardiac function by increasing CF, CO and LV dp/dtmax and decreasing preload CVP or RAP in all four drug-induced failure models. Due to the vasodilator properties of amrinone, afterload, total peripheral resistance (TPR), was reduced in verapamil and procainamide failures as well as in propranolol failure, the only model where TPR increases. In another model of heart failure, in which ouabain-induced arrhythmias preceded procainamide toxicity, amrinone was also an effective cardiotonic agent. Ouabain's inotropic effect was studied in propranolol-induced heart failure. Although an increase in LV dp/dtmax and a decrease in CVP were noted, ouabain (40 micrograms X kg-1 iv) increased TPR and had little effect on the depression in CF and CO. Drug-induced models of heart failure were useful pharmacological tools for evaluating the cardiotonic agent's ability to overcome severe cardiac depression. In propranolol-, verapamil-, procainamide-, and pentobarbital-induced cardiac toxicity, amrinone could be of therapeutic value.

Aminopyridines↗
PubMed1984

Effects of alternating cycle lengths on refractoriness of the His-Purkinje system.

The effects of alternating cycle lengths (bigeminal rhythm) on His-Purkinje system refractoriness were studied in 14 patients using His bundle and right bundle recordings. Programmed atrial stimulation at constant cycle length (method I) was scanned using the atrial extrastimulus technique (A2) and compared with an atrial cycle length of identical duration coupled to A2 on alternate beats (method II). The results showed that (a) despite shorter cycle length of the His-Purkinje system with method II due to effect of A2 on atrioventricular nodal conduction (699 +/- 90 vs. 743 +/- 87 ms, P less than 0.001), the relative refractory period of the His-Purkinje system was always longer with method II (463 +/- 52 vs. 440 +/- 43 ms, P less than 0.001). A similar increase also occurred in effective refractory period of the His-Purkinje system; (b) while functional right bundle branch block occurred in eight patients and functional left bundle branch block in two patients with method I, functional right bundle branch block occurred in all 14 patients and left bundle branch block in seven patients with method II; (c) in two patients where both functional right and left bundle branch block occurred with method I this never was manifest at identical degree of abbreviation of His-Purkinje system cycle length but was manifest at identical abbreviation in each of seven patients with method II; (d) site of conduction delay and/or block during functional right bundle branch block was always proximal, i.e., between the His bundle and right bundle recordings with both methods. During method II this resulted in shortening of the subsequent right bundle cycle length relative to the subsequent His bundle (and of necessity left bundle) cycle length. The finding of increased His-Purkinje system refractoriness despite shorter preceding cycle length of the His-Purkinje system during atrial bigeminy has never been previously described and suggests that classical concepts of His-Purkinje system behavior may require revision in this setting. Secondly, during atrial bigeminy the occurrence of alternating functional bundle branch block cannot be accounted for solely by the degree of abbreviation of His-Purkinje system cycle length, but may be explained by a relative shortening of the next ipsilateral bundle branch cycle length in the bundle manifesting block.

Atrial Function↗
PubMed2004

Loss of atrial contractility is primary cause of atrial dilatation during first days of atrial fibrillation.

Atrial fibrillation (AF) induces a progressive dilatation of the atria which in turn might promote the arrhythmia. The mechanism of atrial dilatation during AF is not known. To test the hypothesis that loss of atrial contractile function is a primary cause of atrial dilatation during the first days of AF, eight goats were chronically instrumented with epicardial electrodes, a pressure transducer in the right atrium, and piezoelectric crystals to measure right atrial diameter. AF was induced with the use of repetitive burst pacing. Atrial contractility was assessed during sinus rhythm, atrial pacing (160-, 300-, and 400-ms cycle length), and electrically induced AF. The compliance of the fibrillating right atrium was measured during unloading the atria with diuretics and loading with 1 liter of saline. All measurements were repeated after 6, 12, and 24 h of AF and then once a day during the first 5 days of AF. Recovery of the observed changes after spontaneous cardioversion was also studied. After 5 days of AF, atrial contractility during sinus rhythm or slow atrial pacing was greatly reduced. During rapid pacing (160 ms) or AF, the amplitude of the atrial pressure waves had declined to 20% of control. The compliance of the fibrillating atria increased twofold, whereas the right atrial pressure was unchanged. As a result, the mean right atrial diameter increased by approximately 12%. All changes were reversible within 3 days of sinus rhythm. We conclude that atrial dilatation during the first days of AF is due to an increase in atrial compliance caused by loss of atrial contractility during AF. Atrial compliance and size are restored when atrial contractility recovers after cardioversion of AF.

Animals↗
PubMed1993

Beneficial effects of the opiate antagonist naloxone on hemodynamics and ventricular function following coronary artery occlusion and reperfusion in the dog.

It has been shown that endogenous opioid peptides (EOP) subserve important roles in cardiovascular regulation and are involved in the pathophysiology of myocardial ischemia, contributing to the deleterious effects. The aim of this study was to evaluate the effects of the opiate antagonist naloxone on the hemodynamics and ventricular function following coronary artery occlusion and reperfusion in the dog, utilizing the technique of cardiac catheterization. During myocardial ischemia and reperfusion, it was found that in the control group, there was reduction in the aortic, left ventricular, right atrial, pulmonary arterial and wedge pressures, and in the left ventricular dP/dt. The reduction in the aortic, left ventricular and pulmonary arterial pressures, and left ventricular dP/dt were significantly attenuated by pretreatment with naloxone. The results indicate a regulatory role of EOP in the cardiovascular function and suggest a possible involvement of EOP in myocardial ischemia and reperfusion causing detrimental effects such as arrhythmias, bradycardia, hypotension and, as shown in this study, impaired hemodynamics and ventricular function. The beneficial effects of naloxone on circulatory dynamics may have clinical implications in the prevention and treatment of ischemic heart disease.

Animals↗
PubMed1999

Electrosurgical treatment of atrial fibrillation with a new intraoperative radiofrequency ablation catheter.

BACKGROUND: To assess the efficacy of a new catheter for intraoperative radiofrequency ablation. METHODS: We operated 35 mitral patients with atrial fibrillation of which 27 had chronic atrial fibrillation with a mean duration of 8 +/- 6 years. Most patients were in functional class III or IV. All patients were operated under cardiopulmonary bypass using sternotomy in 29 patients, right thoracotomy in 5 and left thoracotomy in 1. RESULTS: Bilateral pulmonary vein isolation with radiofrequency catheter ablation was achieved in 7 +/- 4 minutes. There was no mortality or morbidity. Out of the 27 patients with one to three months follow-up 60% were out of atrial fibrillation and 48% had both atria contracting (scores 3 and 4). A longer time is required to assess the end result of these techniques, because the complete healing of the ablation lesions takes 3 to 6 months. CONCLUSIONS: We conclude that with appropriate tools and settings the use of intraoperative radiofrequency catheter ablation is fast, safe and effective. Its indications can be extended to other types of atrial fibrillation patients.

Aged↗
PubMed1992

VDD single pass lead pacing: sustained pacemaker mediated tachycardias unrelated to retrograde atrial activation.

Pacemaker mediated tachycardias (PMTs) are a well known complication of P synchronous pacing. Although the initiating mechanisms are several, all of them are associated with retrograde atrial activation, which is sensed by the atrial sensing channel, resulting in ventricular pacing. In 19 patients suffering from symptomatic AV conduction disturbances and normal sinus node function, a VDD pacing system connected to a single pass ventricular lead with dual chamber electrodes was implanted. The bipolar atrial electrode, floating in the right atrium, was used to detect endocardial atrial electrograms that were differentially processed within the pacemaker for optimal discrimination and filtering of undesirable signals. The widely programmable atrial sensitivity (amplitude and filtering) allowed stable P synchronized ventricular pacing in all patients, but in five of them, sustained PMTs not related to retrograde atrial activation was documented during the follow-up. The common mechanism for the onset and maintenance of these PMTs was traced to the abnormal sensing of the terminal forces of ventricular activation and/or of the T wave. The possibility of interferences between ventricular and atrial electrodes (crosstalk) was also considered. The reduction of atrial channel sensitivity represented in all cases the only effective procedure to prevent this type of PMT. In conclusion, the bet signal to noise ratio is an important endpoint to assure the proper function of a single lead VDD pacing system. Furthermore, using the differential amplifier built within the pacemaker, consideration should be given to the optimal mode of rejection of the terminal forces of the QRS and T wave.

Aged↗
PubMed2004

Doppler echocardiographic evaluation of right ventricular diastolic function in patients with mitral regurgitation.

BACKGROUND AND AIM OF THE STUDY: The effect of left ventricular (LV) pressure overload on right ventricular (RV) diastolic function has been extensively studied. In contrast, no data are available concerning the influence of LV volume overload on RV diastolic function. Accordingly, RV diastolic function was studied in patients with mitral regurgitation (MR) using Doppler echocardiography. METHODS: RV diastolic indices were calculated, using pulsed Doppler echocardiography, in 30 patients (mean age 56.87 +/- 8.58 years) with severe MR, and in 30 healthy control subjects (mean age 56.67 +/- 8.52 years). RESULTS: Compared with controls, MR patients had a significantly lower RV E/A ratio (0.85 +/- 0.12 versus 1.21 +/- 0.16, p <0.001), a significantly prolonged RV isovolumic relaxation time (70 +/- 20 versus 30 +/- 10 ms, p <0.001), a significantly prolonged deceleration time of the transtricuspid E wave (210 +/- 20 versus 140 +/- 10 ms, p <0.001), and a significantly greater right atrial filling fraction (38.58 +/- 4.59 versus 32.58 +/- 3.14%, p <0.001). There was no statistically significant correlation between RV diastolic indices and LV mass index and interventricular septum thickness. CONCLUSION: RV diastolic function in patients with MR is impaired, reflecting prolonged relaxation and redistribution of RV filling into late diastole. Ventricular interdependence constitutes the most likely mechanism of this action.

Adult↗
PubMed1989

[Left ventricular function in right ventricular overload: asymmetry of the left ventricular ejection].

This study clarified regional and global functions of the distorted left ventricle due to right ventricular overload by means of gated radionuclide ventriculography (RNV). Cardiac catheterization and RNV were performed in 13 cases of atrial septal defect (ASD), 13 of pure mitral stenosis (MS), 10 of primary pulmonary hypertension (PPH), and 10 of normal subjects (NL). Right ventricular systolic pressure (RVSP) was 32.9 +/- 13.9, 45.0 +/- 12.2, 88.3 +/- 17.1, and 21.2 +/- 4.5 mmHg, respectively. RNV was performed with a 99mTc-red blood cell in a vivo labeling technique. The end-systolic LAO view of the left ventricle was halved into septal and free-wall sides. The end-diastolic halves were determined in the same plane. Ejection fractions of the global left ventricle (LVEF), global right ventricle (RVEF), the septal half of the left ventricle (SEPEF), and the free-wall half of the left ventricle (FWEF) were obtained. LVEF was 56.8 +/- 9.8% in NL, 52.8 +/- 10.5% in ASD, and 49.5 +/- 12.9% in PPH. In MS, LVEF (47.0 +/- 13.0%) was smaller than those in the other groups. RVEF was 37.0 +/- 5.2% in NL, 43.7 +/- 15.5% in ASD, and 32.8 +/- 11.5% in MS. In PPH, RVEF (25.0 +/- 10.6%) was smaller than those in the other groups. SEPEF was smaller in AS D (42.5 +/- 13.2%), MS (40.4 +/- 13.1%), PPH (40.5 +/- 12.5%) than in NL (53.5 +/- 8.5%). Systolic function of the septal half of the left ventricle was disturbed by right ventricular overload. RVEF (r = -0.35, p less than 0.05) and SEPEF (r = -0.51, p less than 0.01) had negative correlations with RVSP. As RVSP rose, systolic function of the septal half of the left ventricle was more severely disturbed. FWEF was the same among the four groups; NL (57.0 +/- 12.6%), ASD (48.6 +/- 15.2%), MS (50.5 +/- 12.0%), and PPH (51.1 +/- 12.3%). Right ventricular overload does not affect systolic function of FWLV. There was a good correlation between SEPEF and LVEF in NL (r = 0.81), though in PPH this correlation was poor (r = 0.64). In patients with PPH the septal side of the left ventricle does not act as a part of the global left ventricle. Systolic function of the septal side of the left ventricle is disturbed due to the distortion of the ventricular septum, but systolic function of the free-wall side is maintained within a normal range, when the left ventricular myocardium is kept normal.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1976

Total correction of Ebstein's anomaly by replacement with a biological aortic valve without plication of the atrialized ventricle.

For the surgical management of Ebstein's anomaly, the preferred operation will be Hardy's procedure, which preserves the patient's valve. However, we have encountered 3 cases of this disease in which the downward displacement of the tricuspid valve was so severe and the functioning right ventricle was so small that Hardy's method could not be adapted without causing tricuspid regurgitation and making the right ventricular chamber more narrow. We treated these patients by replacing the tricuspid valve with an inverted aortic valve with a stent and not plicating the atrialized ventricle. The results have been proved satisfactory through about 7 years' follow-up, suggesting that our technique will be remarkably effective as a radical corrective operation for Ebstein's anomaly with severe intracardiac abnormalities.

Adolescent↗
PubMed2006

[Left ventricular electromechanical latency period is an additional indicator to upgrade from right to biventricular DDD pacing].

In DDD pacing, the left-ventricular electromechanical latency period defines the duration between premature ventricular stimulation and the prematurely ending left-atrial contribution to left-ventricular filling. It has to be considered in diastolic AV delay optimization. Individual duration of this parameter seemed to reflect the ventricular function. Therefore, we compared the left-ventricular electromechanical latency period due to right ventricular stimulus with the documented ejection fraction of two groups, 33 congestive heart failure patients carrying biventricular systems and 13 right ventricular paced bradycardia patients. A mean latency period of 168+/-26 ms was found in the heart failure patients (ejection fraction: 25+/-5%) which was significantly longer (p=0.0039) compared to the bradycardia patients (ejection fraction: 51+/-12%) with a mean latency of 119+/-13 ms. Thus, an increasing latency period during right ventricular DDD pacing therapy indicates decreasing ejection fraction. A cut-off interval of 135 ms allowed the discrimination of 93% of our patients as having an individual ejection fraction of either up to 35% or above. Thus, the left ventricular electromechanical latency period can be used as an additional parameter indicating the necessity to upgrade from right to biventricular DDD pacing.

Bradycardia↗
PubMed2004

Analysis of right ventricular Doppler tissue imaging and load dependence in patients undergoing percutaneous closure of atrial septal defect.

In patients with volume overload due to atrial septal defect (ASD) and Doppler tissue imaging E'/A' <1 at baseline, right ventricular (RV) myocardial velocities show load independence after closure with a device. Conversely, in patients with ASD with basal E'/A' >1, regional velocities are load-dependent and positively correlate with RV dimension. Because RV Doppler tissue imaging velocities are still in the normal range 1 month after ASD closure, cardiac function does not seem to be affected by the presence of the occluder device.

Adolescent↗
PubMed2001

Congenital diverticulum of the right ventricle associated with coarctation of aorta, atrial and ventricular septal defect and ductus.

Congenital right ventricular muscular diverticula are extremely rare and are usually associated with other congenital cardiac anomalies, (in half of the cases tetralogy of Fallot). They functionally behave like an accessory ventricular chamber which contracts synchronously with the normal ventricles. Less than 30 patients with a right ventricular diverticulum have been reported in literature. An apical right ventricular diverticulum occurs in patients with thoraco-abdominal midline defects or abnormalities of the cardiac position([1]). However, an antero-superior diverticulum is usually associated with other congenital cardiac defects, such as a ventricular septal defect, tetralogy of Fallot, double outlet right ventricle and pulmonary stenosis([2--9]). We report an 11-year-old boy with an antero-superior diverticulum of the right ventricle associated with a coarctation of aorta, ductus arteriosus, and atrial and ventricular septum defects. To the best of our knowledge, such an association has not been reported before.

Aortic Coarctation↗
PubMed1993

Right-to-left interatrial shunt in rats with progressive pulmonary hypertension.

A right-to-left interatrial shunt may prolong survival in patients with pulmonary hypertension presumably because of decompression of the right side of the heart. To test this hypothesis, 74 rats with monocrotaline-induced pulmonary hypertension were followed up weekly with cardiopulmonary exercise testing with a metabolic treadmill system for exercise tolerance, heart rate, oxygen uptake, carbon dioxide production, and survival until subsequent or induced death 8 weeks after monocrotaline treatment. In rats with an interatrial shunt, oxygen uptake and carbon dioxide production were higher and survival was better (n = 22, 27%) than those in rats without a shunt (n = 52, 0%; p < 0.05). For the prospective assessment of the effects of a reversed shunt, 24 other rats underwent a left superior vena cava-to-left atrial appendage anastomosis as a functional interatrial shunt (atrial septal defect group) 4 weeks after monocrotaline treatment when severe pulmonary hypertension had developed and were compared with an additional 25 rats receiving a sham operation. Both groups had exercise capacity depressed to the resting levels by 2 weeks after operation. Although transcutaneous oxygen levels decreased in response to exercise in the atrial septal defect group, uptake and carbon dioxide production stayed higher than those in the sham operation group with significantly better survival 4 weeks after operation (atrial septal defect 30% versus sham operation, 0%; p < 0.05), at which time a reversed shunt was determined with systemic embolization of intravenously infused microspheres. A right-to-left interatrial shunt, anatomic or functional, preserved basal metabolism and prolonged survival in rats with progressive pulmonary hypertension.

Animals↗
PubMed1985

[Right ventricular dysplasia: clinical characteristics of five patients].

The purpose of this study was to elucidate the clinical features of right ventricular (RV) dysplasia, a recently described clinical entity characterized by RV myopathic changes and ventricular tachycardia of left bundle branch block morphology. Five cases were reported, in which the diagnosis was established according to the criteria of Marcus. Case 1, a 33-year-old man, was referred to us for evaluation of his paroxysmal ventricular tachycardia of five years duration. Case 2, a 38-year-old man, was admitted because of shock caused by ventricular tachycardia. In both cases, the QRS configurations during ventricular tachycardia were those of the left bundle branch block pattern, and electrocardiograms during sinus rhythm showed T wave inversions in the right precordial leads and late ventricular potentials. Two-dimensional echocardiography, radionuclide angiography and contrast angiography disclosed RV dilatation and dysfunction with normal left ventricular (LV) function. The biopsied myocardium from the right and left ventricles in Case 2 revealed myocytolysis, a paucity of myofibrils and proliferation of collagen fibers. Case 3, a 73-year-old woman began to experience exertional dyspnea since 16 years of age. Her treatment consisted of bed rest, diuretics and digitalis. In December 1983, her New York Heart Association functional class was III, and physical examinations disclosed a Levine III/VI systolic murmur suggestive of tricuspid regurgitation, jugular vein dilatation, hepatomegaly, and pretibial edema. Electrocardiogram showed atrial fibrillation, incomplete right bundle branch block and T wave inversions in the precordial leads. Chest radiograph revealed marked cardiomegaly (cardiothoracic ratio of 92%). Echocardiography, radionuclide angiography and contrast angiography revealed marked RV dilatation, depressed ejection fraction (RV end-diastolic volume index of 342 ml/m2, and RV ejection fraction of 28%). Case 4, a 20-year-old man, was admitted with a chief complaint of palpitation. Case 5, a 19-year-old man, was referred to us for the evaluation of asymptomatic cardiomegaly, and his cardiothoracic ratio was 54%. A 12-lead electrocardiogram showed right bundle branch block and T wave inversions in the right precordial leads. Ambulatory electrocardiography revealed frequent premature ventricular complexes of the left bundle branch block pattern. Echocardiography, radionuclide angiography, and contrast angiography disclosed RV dilatation and dysfunction in both cases, and mild LV dilatation and dysfunction (LV end-diastolic volume index of 149 ml/m2, LV ejection fraction of 48%) in Case 4.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

[Limitation of disorders of the contractile function of the nonischemic areas of the myocardium during infarct by using the delta-sleep peptide and its cyclic derivative].

The effect of pretreatment with delta-sleep peptide (DSP) and its cyclic analogue (cDSP) on right-atrial myocardial distensibility and contractility disturbances in left-ventricular infarction (according to Selye) was studied in Wistar rats. These peptides, administered in a 20 micrograms/kg dose, 1 hour before the induction of experimental infarction, significantly limited the infarct-related depression of atrial distensibility and contractility, and also reduced atrial resistance to hypoxia and excessive calcium. Since infarction-associated disorders of myocardial structure and function in non-ischemic regions of the heart are due to the emotional-painful stress that accompanies the infarction, it can be assumed that the protective effect of DSP and cDSP consists in limiting the stress-induced response.

Animals↗