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PubMed2001

Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator.

This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.

Defibrillators, Implantable↗
PubMed2004

A fast and simple echocardiographic method of determination of the optimal atrioventricular delay in patients after biventricular stimulation.

The optimization of atrioventricular (AV) delay is known to significantly contribute to maximum cardiac performance. The aim of this study was to validate a new, fast, and simple echocardiographic method of identifying the AV delay that provides the maximum cardiac output (CO). Right heart catheterization and Doppler echocardiography of transmitral filling were performed simultaneously in 18 patients with heart failure and at least minimum functional mitral regurgitation treated with atrial synchronized biventricular pacing. CO derived from catheterization and Doppler filling parameters were measured at the predicted optimal AV delay (oAVD), the short AV delay (oAVD - 50 ms), and the long AV delay (oAVD + 28 ms on average/range, +10 ms to +50 ms) during a constant heart rate. The AV delay was regarded as optimal if the end of atrial contraction (represented by the end of A wave of transmitral filling) coincided with the beginning of ventricular contraction (heralded by the onset of the systolic component of mitral regurgitation). Prediction of the optimal AV delay included the following steps: (1) The maximum AV delay at which full ventricular capture is still preserved was found under electrocardiographic control. (2) This value, decreased by 5 to 10 ms, was designated as "the testing long AV delay," and the time interval from the end of the A wave to the onset of the systolic component of mitral regurgitation (time t1) was measured at this setting. (3) oAVD was simply calculated as "the testing long AV delay"- time t1. The CO measured at the oAVD (4.5 +/- 0.7 1. min-1) significantly exceeded those at the short AV delay (4.3 +/- 0.7 1. min-1, P < 0.01) and the long AV delay (4.4 +/- 0.8 1. min-1, P < 0.01), respectively. The method correctly determined the maximum CO in 78% of the patients. In conclusion, Doppler echocardiography enables very rapid and accurate optimization of AV synchrony in patients after the implantation of a biventricular pacemaker.

Aged↗
PubMed1981

M-mode and two-dimensional echocardiographic features in cardiac amyloidosis.

Twenty-eight patients with cardiac amyloidosis were studied by echocardiography -- 26 by M-mode and 13 by two-dimensional (2D) studies. All had heart failure and biopsy-proved amyloidosis, M-mode features included (1) normal left ventricular (LV) dimension in all; (2) thickened ventricular septum (88%), LV posterior wall (77%), and right ventricular (RV) anterior wall (79%); (3) decreased thickening of ventricular septum (96%) and of LV posterior wall (65%) and reduced LV global function (62%); (4) left atrial enlargement (50%); and (5) pericardial effusion (58%). Two-dimensional echocardiography provided additional features: (1) thickened papillary muscles (five of 13); (2) thickened valves (four of 13); (3) better appreciation of thickened RV wall; and (4) a characteristic "granular sparkling" appearance of thickened cardiac walls -- presumably secondary to the amyloid deposit -- which was noted in 12 of 13 patients. Thus, M-mode echocardiography is helpful in the recognition of cardiac amyloidosis. However, the better appreciation with 2D echocardiography of thickened cardiac walls with a "granular sparkling" appearance in patients with unexplained cardiac failure is virtually diagnostic of cardiac amyloidosis.

Adult↗
PubMed2003

Identification of functional block line in atrial flutter using three-dimensional intracardiac echocardiography.

The crista terminalis (CT) is reportedly a critical barrier for maintaining typical atrial flutter (AFL), but recent observations have suggested the presence of posteromedial functional block, as well as crista conduction. Therefore, this study was designed to identify the correlation between the posterior boundary of AFL and anatomical architecture in the human right atrium (RA) using 3-dimensional (D) intracardiac echocardiography (ICE). In 11 patients with AFL (typical 9, reverse typical 2), mapping with a 10-pole (n=5) or 32-pole (n=6) catheter was performed during AFL. ICE was used to determine the catheter's position relative to the intra-atrial structures. In all patients, double potentials were recorded at the posteromedial RA and the catheter positions were recognized as posterior to the CT by 3-D ICE. Double potentials were not recorded on the CT, and the activation sequence revealed a craniocaudal direction in the 9 patients with typical AFL and caudocranial direction in the 2 patients with reverse typical AFL. These findings demonstrate that the posterior boundary of the AFL circuit is in the sinus venosa region posterior to the CT, which may provide an important insight into the mechanism of maintaining AFL.

Adult↗
PubMedDate not supplied

Lack of progressive "restrictive" physiology after heart transplantation despite intervening episodes of allograft rejection: comparison of serial rest and exercise hemodynamics one and two years after transplantation.

It has been suggested that the cardiac allograft becomes less compliant either because of repeated episodes of rejection, chronic hypertension, or as a direct consequence of immunosuppression. A corollary to this hypothesis is that this reduction in compliance should be a progressive, rather than a static, change. To test this hypothesis, rest and exercise filling pressures, cardiac outputs, and radionuclide ventriculographic systolic and diastolic indices were measured in 20 patients at 1 and 2 years after heart transplant by means of identical protocols at both study times. Between studies 10 of 20 patients had no rejection, five of 20 had one rejection episode, and five of 20 had more than one rejection episode. There were no significant differences in resting or exercise heart rates, pulmonary wedge pressures, cardiac outputs, left or right ventricular ejection fractions, left ventricular peak filling rates, or time to peak filling between the studies at 1 and 2 years. Only resting right atrial pressure increased between year 1 and year 2 (6 +/- 2 mm Hg vs 8 +/- 4 mm Hg, p = 0.035). These data demonstrate that cardiac allograft function is unchanged between 1 and 2 years after transplantation, despite episodes of intervening rejection and continued immunosuppression. The data further suggest that the previously reported decrease in cardiac allograft compliance does not appear to be caused by a progressive intrinsic abnormality in the allograft, and that other mechanisms for "restrictive" allograft physiology should be sought.

Adolescent↗
PubMed1990

Effects of bilateral transvenous diaphragm pacing on hemodynamic function in patients after cardiac operations. Experimental and clinical study.

The effects of bilateral transvenous diaphragm pacing and intermittent positive-pressure ventilation on hemodynamic function were compared by animal experiment in 18 dogs and by clinical study in 14 patients during the postoperative period after cardiac operations. Aortic, pulmonary arterial, right atrial, and left atrial pressures (transmural) and aortic flow were increased by diaphragm pacing in the canine experiment. In dogs with induced tricuspid insufficiency, aortic pressure, right and left atrial pressures, and aortic blood flow increased, similar to the results obtained in the clinical study. Diaphragm pacing produced a sufficient tidal volume (7.2 to 12 ml/kg) for maintenance of normal blood gas levels in the patients, all of whom recovered spontaneous breathing without any weaning problems after 2 to 6 hours of diaphragm pacing. The catheter electrode used for stimulation was placed 30 mm away from the sinus node to avoid arrhythmias. Respiratory control by diaphragm pacing is hemodynamically superior to that by intermittent positive-pressure ventilation, and its efficacy is expected, especially in critical cases or in diseases or conditions in which the decrease in the load of the right heart affects the hemodynamic status of the patient.

Animals↗
PubMed1988

[Right ventricular function in cardiovascular disease evaluated by magnetic resonance imaging].

The usefulness of ECG-gated magnetic resonance imaging (MRI) in evaluating right ventricular architecture and function was assessed by measuring right ventricular wall thickness, wall motion, and areas of the right ventricular cavities of seven normal subjects and 46 with cardiac disease, including atrial septal defect (ASD: six cases), hypertrophic cardiomyopathy (HCM: 19), dilated cardiomyopathy (DCM: eight), and old myocardial infarction (OMI: 13 cases). A superconductive MRI system was used. Transverse images at the level of the tricuspid valve were obtained for measurements. ECG-gated MRI clearly showed the right ventricular myocardium throughout the cardiac cycles and facilitated measuring wall thickness and cross-sectional areas of the right ventricular cavity in all subjects. In normals the mean value and standard deviation of the anterior wall thickness of the right ventricle and the area index of the right ventricular cavity at end-diastole were 3.4 +/- 0.7 mm and 10.6 +/- 1 cm2/m2, respectively. The anterior and lateral walls and tricuspid annulus moved inward to the right ventricular cavity in systole, and the excursion of the lateral wall and tricuspid annulus was larger than those of the anterior wall. The interventricular septum (IVS), however, moved outward to the left ventricle in systole. The anterior wall thickness of the right ventricle in patients with HCM was 5.8 +/- 1.4 mm thicker than that of normal subjects. In contrast to normals, the area index of the right ventricular cavity was larger in patients with ASD (18.4 +/- 5.4 cm2/m2) and smaller in patients with HCM (9.1 +/- 1.6 cm2/m2). The IVS moved inward in all patients with ASD and in several patients with HCM. The anterior and lateral wall motion was decreased in patients with ASD and DCM.

Adult↗
PubMed1979

The right ventricular myocardium in Ebstein's anomaly: a morphometric histopathologic study.

Ebstein's anomaly of the tricuspid valve is associated with right ventricular dilatation in approximately two-thirds of cases. Dilatation may be massive. It involves not only the right ventricular wall proximal to the tricuspid valve (atrialized ventricle) but also the right ventricle distal to the valve (funtional right ventricle), including the right ventricular infundibulum. For further definition of the pathogenesis of dilatation of the functional right ventricle (distal chamber), a morphometric histopathologic study was performed on 10 hearts with Ebstein's anomaly and 10 normal age-matched control hearts. In the group with Ebstein's anomaly, five hearts exhibited dilated ventricles and five did not. The study demonstrated that dilatation of the right ventricle in Ebstein's anomaly was associated not only with thinning of the wall but also with an absolute decrease in the number of myocardial fibers counted through the thickness of the wall from endocardium to epidcardium.

Dilatation, Pathologic↗
PubMed1983

Right ventricular function during left heart bypass.

Right heart failure may occur during mechanical support of the left ventricle (LV). Right ventricular (RV) functional changes were studied in eight dogs (26.9 +/- 1.4 kg) subjected to various degrees of left heart bypass (LHBP) with a roller pump. The venous return to the right atrium was controlled with a second pump. RV function was evaluated by peak RV developed pressure, its first derivative (dp/dt), and mean RA pressure measurements. Left atrial, LV, and aortic pressure and both roller pump flows were determined. Incremental increases in LHBP flow ratio ([LHBP flow x 100] divided by venous return flow) to 60%, 90%, and 100% were associated with decrements in RV dp/dt from the control of 212 +/- 17 torr/sec to 192 +/- 16, 178 +/- 16, and 168 +/- 13 torr/sec, respectively. Biventricular bypass or total cardiopulmonary bypass with extracorporeal membrane oxygenation seems to be indicated if LHBP flow ratio greater than 90% is required to maintain adequate body perfusion. Maximal LV decompression to obtain the greatest reduction of LV myocardial oxygen consumption may not be the ideal goal during LV mechanical assistance.

Animals↗
PubMedDate not supplied

Enlargement of the right ventricle using a viable atrial pedicle graft.

A viable muscle pedicle of right atrial wall was used to enlarge the right ventricle in 5 dogs. The procedure consistently resulted in an increase in right ventricular circumference of approximately 20%. Although ventricular function was adequate to permit survival, cardiac index did not increase appropriately to an elevation in preload. Morphologic studies demonstrated later scarring and thickening of the muscle pedicle suggesting the graft had not maintained its contractile nature.

Animals↗
PubMed1981

Two methods for improved venous access in acute leukemia patients.

Arteriovenous fistulae and long-term indwelling right atrial (Hickman) catheters have been used as methods to improve venous access in patients with acute leukemia. The creation of 28 fistulae provided short duration of function (median, 12 days), with eight fistulae functioning less than 24 hours. Complications were negligible, and no increase in the incidence of bacteremia occurred. Fifty-one Hickman catheters have been placed, with a median placement granulocyte count of 335/microliters. The median duration of function has been 91 days or more, with 19 still functioning and 25 other catheters functioning at the time of the patient's death. Complications have been minimal, with substantial postoperative hemorrhage occurring primarily in patients with active disseminated intravascular coagulopathy at the time of catheter placement. Catheter-associated infections were uncommon. The overall incidence of bacteremia was not increased in patients with Hickman catheters, and 28 of the 30 bacteremias that occurred while catheters were in place (three catheter associated) resolved without catheter removal. The Hickman catheter is a safe, reliable device for improvement of venous access in adult patients with acute leukemia.

Acute Disease↗
PubMed1998

[Sinus node dysfunction after complete correction of tetralogy of Fallot. Report of a case].

Atrioventricular conduction defects after complete correction of tetralogy of Fallot are well known and their prevalence is decreasing with improved operative techniques. On the other hand, sinus node dysfunction has not been described after this type of surgery. The authors report the case of a 24 year old patient operated at the age of 2 for a favourable form of tetralogy of Fallot. In the long-term, this patient had a minimal anatomical sequel (mild pulmonary insufficiency) and first degree AVB with complete right bundle branch block with sinus bradycardia on the surface ECG. A recent aggravation of the patient's functional status led to rhythmological investigation which showed chronotropic atrial incompetence with nodal atrioventricular delay. The patient was implanted with a permanent DDD cardiac pacemaker programmed in the DDDR mode with a good outcome. Atrial chronotropic incompetence is one of the modes of expression of sinus node dysfunction. This has not been previously described in this context. This form of sinus node dysfunction should be systematically excluded after surgical cure of tetralogy of Fallot by exercise stress testing and 24 hour Holter ECG. Symptomatic patients are greatly improved by permanent cardiac pacing with hysteresis.

Adult↗
PubMed2004

Amiodarone inhibits the 3,5,3'-triiodothyronine-dependent increase of sodium/potassium adenosine triphosphatase activity and concentration in human atrial myocardial tissue.

In animal models the function of the sodium pump (sodium/potassium-adenosine triphosphatase [Na+/K(+)-ATPase]) is enhanced by 3,5,3'-triiodothyronine (T3) and inhibited by the antiarrhythmic agent amio. However, it is still unclear whether the effect of the drug on Na+/K(+)-ATPase depends on the interference with thyroid hormone action. We evaluated the interaction of T3 with amiodarone on Na+/K(+)-ATPase activity and site number in human myocardium. Right atrial slices were cultured with (T3+) and without (T3-) 3 nM T3 in presence and absence of amiodarone at therapeutical dose (1.5 microM). When compared to T3+, T3- preparations showed decreased 3H-ouabain binding (p < 0.004) and lower 20-minute and 45-minute 86Rb-uptake (p < or = 0.004). Amiodarone caused an average 49% reduction of the T3-dependent 3H-ouabain binding and decreased the Western blot signal for the Na+/K(+)-ATPase alpha1 subunit. The drug also inhibited T3-dependent increase in 86Rb-influx at 20 and 45 minutes by 66% and 42%, respectively, without affecting the affinity of the pump for K+. No differences were found in the 3H-ouabain binding and 86Rb-uptake of T3-, T3- amio and T3(+)-amio. In conclusion, T3 stimulates the Na+/K(+)-ATPase in human atrial myocardium by increasing the number of ouabain-binding sites, whereas amiodarone decreases the sodium pump function secondarily to the antagonism with thyroid hormone.

Amiodarone↗
PubMed2007

Endothelin-1/endothelin-3 ratio: a potential prognostic factor of pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare condition characterized by elevated pulmonary artery pressure leading to right-heart failure and death. Endothelin (ET)-1 has been shown to play a significant pathogenic role in PAH. ET-3 has not yet been investigated in PAH. METHODS: ET-1 and ET-3 plasma concentrations were measured in 33 PAH patients prior to any specific PAH therapy and in 9 control subjects. In PAH patients, hemodynamic parameters measured by right-heart catheterization, 6-min walk distance (6MWD), New York Heart Association (NYHA) functional class, and time until lung transplantation or death were recorded. RESULTS: In patients with PAH, levels of ET-1 were increased while those of ET-3 were decreased, as compared to control subjects (p < 0.005 for both comparisons). ET-1/ET-3 ratio varied little in control subjects, while it increased threefold in PAH patients (p < 0.0001). ET-1 correlated positively with right atrial pressure (RAP), indexed total pulmonary resistance, and negatively with cardiac index and venous saturation of oxygen (Svo(2)). ET-3 correlated positively with 6MWD. ET-1/ET-3 ratio correlated positively with RAP, negatively with Svo(2) and 6MWD, and was also associated with NYHA functional class. ET-1/ET-3 ratio was associated with prognosis in this sample of PAH patients treated with specific therapies. CONCLUSIONS: PAH is characterized by elevated ET-1 and ET-1/ET-3 ratio and decreased ET-3 plasma concentrations. All of them correlate with hemodynamic and clinical markers of disease severity. ET-1/ET-3 ratio might be a novel prognostic factor in PAH. These preliminary data should be validated in a large prospective multicenter cohort of PAH patients.

Adult↗
PubMed1982

[Study on right and left atrial dynamics in chronic constrictive pericarditis by esophageal echocardiography].

In 9 normal subjects (N) and 4 patients with chronic constrictive pericarditis (CP) with normal sinus rhythm, esophageal echocardiography was performed to obtain simultaneous echograms of the right atrial free wall and the interatrial septum, and both atrial dynamics were evaluated. In spite of increased mean right atrial and mean pulmonary arterial wedge pressures in CP, there were no significant differences in left, right and total atrial end-diastolic dimensions between N and CP. This indicates that there is a decrease in compliance of atrio-pericardial system in CP. Atrial shortening of both atria during active atria contraction was decreased in CP, while there was no significant difference in atrial dimension measured at the beginning of the active atrial shortening between N and CP. This impaired pump function might be due to increased ventricular late-diastolic pressure or organic change in the atrial muscle. The passive enlargement of both atria was impaired during atrial filling phase in CP. Thus, it was concluded that in CP the active shortening and passive enlargement of the right and left atria are decreased, and the atria tend to be a conduit.

Adult↗
PubMed2005

Optimal side of implant for single-lead VDD pacing: right-sided versus left-sided implantation.

BACKGROUND: Atrial undersensing occurs in a considerable number of patients with single-lead VDD pacing. This study tried to determine the role of implant side in maintenance of the VDD mode in patients with isolated atrioventricular (AV) block. METHODS: Eighty-two patients with isolated AV block (46 females; mean age, 58 +/- 17 years) received a single-lead VDD pacemaker (Medtronic Kappa, n = 70 and St. Jude Medical Affinity, n = 12). The patients were randomly assigned to one of two implantation groups (group I: right-sided VDD and group II: left-sided VDD). In each group, the P-wave amplitudes were determined at implantation, predischarge, 2-month, and 6-month follow-up. At each follow-up visit, stored event histograms of pacemaker were also retrieved. The atrial sensing measurements were compared between two groups. RESULTS: Implantation was easier from right side (1.7 +/- 1.0 vs 2.8 +/- 1.7 attempts, P = 0.001). Implant P-wave was higher in group I compared to group II (4.2 +/- 1.7 vs 2.7 +/- 1.0 mV, P < 0.0001). During follow-up, higher P-wave amplitudes were obtained in group I both at predischarge (2.6 +/- 1.3 vs 1.4 +/- 1.1 mV, P < 0.0001), 2-month (2.8 +/- 1.8 vs 1.3 +/- 1.0 mV, P < 0.0001), and 6-month (2.9 +/- 1.7 vs 1.3 +/- 0.9 mV, P < 0.0001) evaluations but remained stable throughout the 6 months in both groups. After implantation, VDD function was better maintained in group I than group II (100% vs 90%, P = 0.026). Incidence of atrial undersensing was lower in group I than group II (P = 0.026) in last follow-up visit. CONCLUSIONS: Implant side has a significant influence on atrial sensing performance in single-lead VDD pacing. Thus, right-side implantation should be the preferred approach for the implantation of VDD single-lead systems.

Adolescent↗
PubMed1991

Differing susceptibilities to cold preservation of rat atria and ventricles.

The susceptibilities of atria and ventricles to cold preservation were studied in rat hearts. Rat hearts were stored in Collins' solution at 4 degrees C for 0, 12, or 24 hours, and the atrial and ventricular function was measured in a working heart model and in isolated atrial and papillary muscle preparations. In working heart preparations, cardiac output decreased to 0 ml/min and other parameters of ventricular function (systolic and end-diastolic pressure and dP/dt of the left ventricle) markedly deteriorated after 12 hours of preservation. After 24 hours, no contraction of the left ventricle was observed despite the presence of atrial contraction. In isolated atrial muscle preparations, the rate of spontaneous beating of the right atrium was not affected by cold preservation. The twitch contractions of right and left atria were attenuated but elicited after 24 hours. In electrically driven papillary muscles, twitch contractions were also markedly attenuated by 12 hours of preservation and were abolished after 24 hours. The positive inotropic effect of isoproterenol was also markedly attenuated in the atrial preparations by cold preservation. However, the positive chronotropic response to isoproterenol and the negative chronotropic and inotropic responses to carbachol were little affected by cold preservation. Intramural cholinergic and adrenergic nerve stimulation produced first negative and then positive effects on the beating rate and twitch contraction in the isolated right atria. Cold preservation selectively attenuated and finally abolished the adrenergic responses. In the ventricles, the adenosine triphosphate and creatine phosphate content significantly decreased and the lactate content increased with an increase in the preservation period. On the other hand, changes of such metabolites in the atria were either not observed or were much smaller. These results suggest that atrial function is maintained better than ventricular function in the cold-preserved heart.

Animals↗

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