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Biomedical subjects

G Kreiner

Publications and source records attributed to G Kreiner.

At least 19 recordsLinked to original sources
PubMed1998

Benign prognosis of early sinus node dysfunction after orthotopic cardiac transplantation.

Previous reports raised concern about the prognosis of patients with sinus node (SN) dysfunction after cardiac transplantation and led to a low threshold for permanent pacemaker (PM) placement at most institutions. The present study addresses the survival in patients with normal and impaired post operative SN function and the effect of permanent pacing with respect to overall and cardiac mortality. There were 120 patients with normal (corrected SN recovery time < 520 ms, group I) and 47 patients with imparied SN function (corrected SN recovery time > 520 ms and/or sinus arrest +/- escape rhythms). Pacing support was deemed unnecessary in 23 of 47 patients with SN dysfunction (group II; asymptomatic SN bradycardia and corrected SN recovery time 3,812 +/- 5,800 ms) while a total of 24 patients had PM placement a mean of 29 +/- 44 days after transplantation (symptomatic bradycardia or absence of sinus rhythm at discharge, group III). Patients were followed for a mean of 46.7 months. Thirty-five deaths occurred during the study period. Sixteen deaths were cardiac but none were causally related to the SN dysfunction (graft failure due to rejection or atheropathy n = 14; myocardial infarction n = 2). Four of these cardiac deaths were sudden and all occurred in the presence of widespread structural abnormalities (rejection/vasculopathy/myocardial infarction). SN dysfunction was not related to overall (P = 0.25) or cardiac mortality (P = 0.33). Regarding either endpoint, patients who had permanent PM placement did no better than their unpaced counterparts in group II (P = 0.53 and P = 0.33, overall and cardiac mortality, respectively). Likewise, survival did not differ between groups I and III for either endpoint (P = 0.77, P = 0.65, respectively). These data suggest that patients with mild SN abnormality, who are in sinus rhythm at the time of discharge, can be followed by observation without specific therapy.

Adult↗
PubMed1998

Atrioventricular nodal reentry tachycardia in patients with sinus node dysfunction: electrophysiologic characteristics, clinical presentation, and results of slow pathway ablation.

INTRODUCTION: Sinus node dysfunction (SND) is frequently associated with impaired AV conduction. This study investigated the electrophysiologic properties of dual AV nodal pathways in patients suffering from both SND and AV nodal reentrant tachycardia (AVNRT). METHODS AND RESULTS: Two groups of patients with slow-fast AVNRT underwent invasive electrophysiologic testing and catheter ablation of the slow pathway. Group A comprised 10 patients with SND (age 70 +/- 8 years). Group B included 10 age-matched patients without SND (age 69 +/- 7 years; P = NS) who served as controls. Patients of group A exhibited prolongation of the anterograde Wenckebach cycle lengths (WBCLs) of both the fast pathway (559 +/- 96 vs 361 +/- 38 msec; P < 0.01) and the slow pathway (409 +/- 57 vs 339 +/- 32 ms; P < 0.01). However, the delta between the WBCLs of the fast and the slow pathways was larger in patients of group A (150 +/- 80 vs 22 +/- 20 msec; P < 0.01). Retrograde fast pathway conduction was well preserved with no difference in WBCLs (356 +/- 42 vs 330 +/- 47 msec; P = NS). Cycle lengths of AVNRT were longer in group A (468 +/- 46 vs 363 +/- 37 msec; P < 0.01). Clinically, all patients of group A suffered from multiple episodes of AVNRT per week, which was not the case in any patient of group B (P < 0.01). Catheter ablation of the slow pathway eliminated AVNRT in all patients without complications. CONCLUSIONS: Patients with AVNRT and SND exhibit characteristic electrophysiologic alterations of both AV nodal pathways. Clinically, this results in significantly more frequent episodes of tachycardia. Slow pathway ablation appears to be safe and effective in these patients.

Aged↗
PubMed1997

Significance of morphological abnormalities detected by MRI in patients undergoing successful ablation of right ventricular outflow tract tachycardia.

BACKGROUND: MRI can demonstrate subtle morphological changes of the right ventricle in patients with idiopathic right ventricular outflow tract tachycardia (RVOT). The present study examines the incidence and significance of right ventricular (RV) abnormalities detected by MRI with respect to the site of successful radiofrequency catheter ablation of the clinical tachycardia. METHODS AND RESULTS: The study population comprised 20 patients (mean age, 40+/-12 years) undergoing elimination of recurrent RVOT by radiofrequency catheter ablation. MRI studies were performed before ablation to assess RV volumes and function, as well as structural abnormalities of the RV myocardium. Ten healthy age- and sex-matched subjects served as control subjects. The successful ablation sites, as documented by radiographs of the catheter position, were compared with MRI findings. Patients with RVOT showed no difference in respect to RV volumes and ejection fractions compared with control subjects. Whereas RV abnormalities were limited to prominent fatty deposits of the right atrioventricular groove extending into the inlet portion of the RV wall in 2 of 10 control subjects, MRI studies demonstrated morphological changes of the RV free wall in 13 (65%) of 20 patients with RVOT, including presence of fatty tissue (n=5), wall thinning (n=9), and dyskinetic wall segments (n=4). Eight of these patients had additional fat deposits, thinning, or a saccular aneurysm in the RV outflow tract, corresponding with the ablation site in 6 patients. CONCLUSIONS: In RVOT, structural abnormalities of the right ventricle can be detected in a substantial number of patients despite normal RV volumes and global function. MRI abnormalities within the RV outflow tract are significantly associated with the origin of tachycardia.

Adult↗
PubMed1997

Does Ca2+ channel blockade modulate the antidepressant-induced changes in mechanisms of adrenergic transduction?

We investigated how the L-type calcium channel blockade (CCB) with nifedipine affects the cyclic AMP responses to noradrenaline or isoproterenol in cerebral cortical slices from rats receiving antidepressant treatments that induce (electroconvulsive shock, imipramine) or do not induce (amitriptyline) beta-downregulation. To assess the role of protein kinase C (PKC) in receptor crosstalk under CCB conditions, the cyclic AMP responses were tested also in the presence of a PKC activator, TPA. CCB alone induced no changes, but modulated the action of those antidepressants that down regulate the beta-adrenergic system. Chronic ECS and imipramine treatments were differently affected. ECS, under conditions of CCB, down regulated the response to isoproterenol in the presence of TPA, while imipramine ceased to block the TPA-potentiation of cyclic AMP responses. Thus, CCB affects the processes related to the antidepressant-induced changes on the crosstalk between alpha1- and beta-adrenergic receptors, depending on the specific properties of the antidepressant.

Adrenergic Agents↗
PubMed1997

Relation between left atrial size and secondary atrial arrhythmias after successful catheter ablation of common atrial flutter.

Catheter ablation provides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. The study population comprised 17 patients (12 men, 5 women, age 32-74 years) who underwent successful radiofrequency catheter ablation of common atrial flutter. Common atrial flutter did not recur in any patient during a median follow-up time of 8 (range 1-25) months. Within a median of 7 (range 1-223) days, however, symptomatic atrial tachyarrhythmias occurred in 8 of 17 patients (47%): uncommon atrial flutter (n = 4); atrial fibrillation (n = 3); and both uncommon atrial flutter and atrial fibrillation in one patient. Preablation left atrial volume was significantly larger in patients who developed secondary arrhythmias compared with patients who remained in sinus rhythm (57.9 +/- 15.6 vs 43.7 +/- 16.4 cm3, P < 0.05). Enlarged left atrial volume dichotomized at 51 cm3 independently predicted postablation atrial arrhythmias (X2 = 5.11, rel. risk = 5.3, P < 0.05). On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patients with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.

Adult↗
PubMed1997

Demonstration of retrograde conduction over an atriofascicular accessory pathway.

INTRODUCTION: Absence of retrograde conduction over a right atriofascicular accessory pathway causing reciprocating tachycardia has been considered a hallmark of this clinical entity. METHODS AND RESULTS: This report describes successful catheter ablation in a patient presenting with the distinctive pattern of preexcited left bundle branch block tachycardia utilizing a right atriofascicular accessory pathway. This pathway, however, exhibited the unique capability of ventriculoatrial conduction. Both anterograde and retrograde conduction were characterized by "node-like" properties. CONCLUSION: Demonstration of retrograde accessory pathway conduction in this particular setting does not exclude the diagnosis of a single, atriofascicular accessory pathway.

Adult↗
PubMed1996

Decrease in pacemaker incidence after orthotopic heart transplantation.

A decrease in sinus node dysfunction and pacemaker requirement after orthotopic heart transplantation was observed over a 6.5-year period, probably indicating the effect of a learning curve. Indirect evidence suggests a traumatic genesis of sinus node dysfunction after cardiac transplantation.

Arrhythmia, Sinus↗
PubMed1996

Effect of slow pathway ablation on ventricular rate during atrial fibrillation. Dependence on electrophysiological properties of the fast pathway.

BACKGROUND: Catheter ablation of the posteroseptal right atrium has been proposed for control of ventricular rate in patients with tachycardic atrial fibrillation (AF). However, the exact mechanism of rate control is unclear. Because the ablation site corresponds to the location of the slow pathway in patients with AV nodal reentry tachycardia (AVNRT), we investigated whether selective ablation of this posterior AV nodal input can provide a sufficient reduction in heart rate during AF. METHODS AND RESULTS: In 30 patients with AVNRT, conduction properties of the AV nodal pathways were determined before and after slow pathway ablation. AF was induced by burst pacing at baseline and after ablation, and the mean ventricular cycle length was determined. After slow pathway ablation, the mean ventricular cycle length during AF increased (449 +/- 98 versus 515 +/- 129 milliseconds, P < .01). At baseline, the mean ventricular cycle length correlated with the Wenckebach cycle length of both the slow (r = .90) and fast (r = .86) pathways. After ablation, the mean ventricular cycle length was extremely well determined by the Wenckebach cycle length of the fast pathway (r = .94). However, the slope of the regression line was significantly steeper compared with baseline (1.50 versus 0.77, P < .0001), illustrating that the reduction in ventricular rate was not as evident if the fast pathway had a short Wenckebach cycle length. CONCLUSIONS: Selective elimination of the slow pathway reduces ventricular rate during AF. However, in patients with a short Wenckebach cycle length of the anterior AV nodal input that causes tachycardic AF, this effect may be insufficient to provide adequate control of ventricular rate.

Adult↗
PubMed1995

Phorbol-12,13-dibutyrate improves the quality of cytogenetic preparation in lymphoid malignancies.

In cytogenetic preparation of lymphoid malignancies we investigated the quantitative and qualitative impact of phorbol-12,-13-dibutyrate (P) and of this tumor promoter in combination with the calcium ionophore A23187 (PA). Using parallel cultures of unstimulated and stimulated preparations, the effect was examined in 13 patients with malignant lymphomas and six patients with acute lymphoblastic leukemias (ALL). Focusing on high-quality analyzable metaphases, the best results were found in seven of 13 cases with lymphomas and five of six patients with ALL in the cultures supplemented with phorbol-12,13-dibutyrate. The yield of metaphases of good quality regarding length, spreading, and banding of chromosomes was regularly better in P-stimulated 24-hour culture (p < 0.05), followed by 48-hour cultures stimulated with P alone. Addition of the calcium-ionophore was of no further benefit. The yield of the unstimulated direct harvest was rather poor in nearly all patients investigated. Because no mutagenic effect of P was observed, the use of this mitogen may offer interesting perspectives in cytogenetic analysis of lymphoid malignancies and perhaps also in other tumors with low mitotic indexes.

Calcimycin↗
PubMed1995

Myocardial m-[123I]iodobenzylguanidine scintigraphy for the assessment of adrenergic cardiac innervation in patients with IDDM. Comparison with cardiovascular reflex tests and relationship to left ventricular function.

Cardiac imaging using m-[123I]iodobenzylguanidine (mIBG) reflects sympathetic myocardial innervation. In patients with insulin-dependent diabetes mellitus (IDDM), the following were studied: 1) the prevalence of derangements of cardiac autonomic innervation as detected by mIBG scintigraphy in comparison with cardiovascular reflex tests and 2) the relationship between adrenergic cardiac innervation and left ventricular (LV) function. Twenty-four patients with IDDM without overt heart disease were studied after silent coronary artery disease was excluded by 201Tl scintigraphy. Cardiac innervation was evaluated by both mIBG scintigraphy (tomographic imaging) and cardiovascular reflex tests. Systolic (ejection fraction [EF] percentage) and diastolic (peak filling rate [PFR] defined as end-diastolic volumes per second [EDV/s]) LV function were determined by equilibrium radionuclide angiography at rest and during bicycle exercise. mIBG scintigraphy was also performed in 10 control subjects. All control subjects exhibited a normal myocardial mIBG distribution. Among diabetic patients, only six had normal mIBG scans (group 1), whereas 18 had evidence of regional adrenergic denervation (group 2). Reflex tests suggested cardiac autonomic neuropathy in only seven of these patients (P < 0.01 vs. mIBG). All patients had a normal EF at rest. However, group 2 showed an impaired response to exercise as indicated by a smaller increase in EF (5 +/- 6 vs. 13 +/- 5%, P < 0.05) and a lower PFR (5.9 +/- 0.8 vs. 7.3 +/- 1.2 EDV/s, P < 0.01). Myocardial mIBG scintigraphy reveals that in patients with IDDM, sympathetic myocardial dysinnervation is much more common than previously thought. Furthermore, subclinical LV dysfunction is related to derangements of adrenergic cardiac innervation.

3-Iodobenzylguanidine↗
PubMed1994

Beneficial hemodynamic effects of prostaglandin E1 infusion in catecholamine-dependent heart failure: results of a prospective, randomized, controlled study.

OBJECTIVE: To study the hemodynamic effects of prostaglandin E1 (PGE1) administered in addition to a standard catecholamine infusion in patients with severe chronic heart failure. DESIGN: Prospective, placebo-controlled, randomized, single-blind study. SETTING: Intensive care unit at a university hospital. PATIENTS: Thirty patients with severe chronic heart failure, New York Heart Association functional class IV (28 men, two women, with a mean age of 54 +/- 2 yrs, mean left ventricular ejection fraction 10 +/- 0.6%). All patients received oral therapy with digitalis, furosemide (mean dose 300 +/- 46 mg/day), and enalapril (20 +/- 2.7 mg/day). INTERVENTIONS: Hemodynamic measurements using pulmonary artery flotation catheters were performed at baseline, > or = 24 hrs after standardized catecholamine infusion with dopamine (3 micrograms/kg/min) and dobutamine (5 micrograms/kg/min), as well as 48 hrs after randomization to infusion therapy with PGE1 (30 ng/kg/min) or a placebo. MEASUREMENTS AND MAIN RESULTS: The addition of PGE1 to an ongoing catecholamine infusion in 20 patients caused a 16 +/- 4% decrease in mean pulmonary arterial pressure (p < .001), a 22 +/- 5% decrease in pulmonary artery occlusion pressure (p < .0001), a 24 +/- 8% decrease in pulmonary vascular resistance index (p < .001), a 20 +/- 9% decrease in right atrial pressure (p < .01), a 14 +/- 3% decrease in mean arterial pressure (p < .001), and a 29 +/- 4% decrease in systemic vascular resistance index (p < .0001). These PGE1-induced decreases occurred without a change in heart rate. Stroke volume index increased with PGE1 therapy by 34 +/- 7% (p < .0001), and cardiac index increased by 34 +/- 6% (p < .0001). No hemodynamic changes were observed during combined infusion with catecholamines and placebo in ten patients. CONCLUSION: PGE1 improves the hemodynamic state in end-stage chronic heart failure patients already receiving a standard dose dopamine/dobutamine infusion.

Alprostadil↗
PubMed1994

Sinus node dysfunction after orthotopic heart transplantation: the Vienna experience 1987-1993.

In the present study, the annual incidence of postoperative sinus node dysfunction and the type of sinus node abnormality after cardiac transplantation were followed over a 6 1/2-year period in 185 patients. Each year the sinus node function was systematically characterized by rhythm and corrected sinus node recovery time in a significant number of patients. Over the entire study period, there were 131 patients with normal sinus node function (corrected sinus node recovery time 318 +/- 55 msec) while 54 patients had latent (n = 24, sinus rhythm, corrected sinus node recovery time 8,053 +/- 2,198 msec) or manifest (n = 30, absence of sinus rhythm or pacemaker dependence) sinus node dysfunction. Twenty-nine patients had pacemaker placement. The incidence of sinus node dysfunction declined in absolute terms and when indexed by the actual number of patients transplanted per year (index 1987: 38.5; 1998: 17.6; 1989: 23.2; 1990: 29.1; 1991: 10.4; 1992: 7.5; 1993: 2.2). Among those with sinus node dysfunction, the annual percentage of patients presenting with prolonged recovery time, escape rhythm, and those reverting back to sinus rhythm until discharge did not change significantly over the study period (P = 0.22). On multivariate analysis, only the date of transplantation was significantly associated with the occurrence of postoperative sinus node deficiency (P = 0.0007) while age of recipient (P = 0.85) or donor (P = 0.96), the type of cardioplegia used (P = 0.09) and ischemic time (P = 0.09) were insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Differential diagnosis of tachycardic arrhythmias and its importance for therapeutic decisions].

The widespread application of catheter ablation techniques has significantly affected the meaning of non-invasive evaluation of both supraventricular and ventricular tachycardias. In patients with different forms of supraventricular tachycardias radiofrequency current ablation offers comparable high success rates. Therefore, since non-invasive and invasive classification of supraventricular tachycardias agree only in 80% of patients, the diagnosis based on non-invasive means may constitute a bias, but does not obviate the need for a scrutinized preablation electrophysiologic study to determine the very type of tachycardia. In contrast, in patients with ventricular tachycardias a manyfold of different therapies is available: antiarrhythmic drug medication, catheter ablation or surgical intervention including the implantation of programmable cardioverters/defibrillators. The selection of the optimal therapy, however, is predominantly dependent on the clinical presentation of tachycardia, on the type and the severity of the underlying structural heart disease and on the potential mechanism of tachycardia.

Anti-Arrhythmia Agents↗
PubMed1993

Management of elderly patients with the Wolff-Parkinson-White syndrome: is less aggressive treatment justified?

To study the age-related differences in Wolff-Parkinson-White syndrome an elderly group of 20 patients aged 40-65 years was compared to a younger group of 26 patients aged 18-39 years with respect to clinical profile and electrophysiological characteristics. The two groups were comparable in terms of the mechanism of reentry tachycardia, accessory pathway location, the number of patients reporting syncopal episodes, and the incidence of inducible and/or documented atrial flutter/fibrillation while only elderly patients had also atrial tachycardias. The elderly group was characterized by a higher incidence of associated organic heart disease and a significantly higher percentage of resuscitation from circulatory arrest. Cardiocirculatory arrest due to arrhythmias was the event leading to transferral to our hospital in 30% of elderly patients compared with 7.7% in the younger group. Analogous results were obtained when stratified according to the age at manifestation of tachyarrhythmias (< 30, > or = 30 years), a history of cardiopulmonary resuscitation being the only significant difference between the two groups. There was no difference in any electrophysiologic parameter between the two age groups or with respect to the age at manifestation of arrhythmias. It is concluded that elderly patients with the Wolf-Parkinson-White syndrome should be managed as aggressively as their younger counterparts. In particular, manifestation of arrhythmias due to Wolff-Parkinson-White syndrome beyond age 30 should not be regarded as a more benign variation of the syndrome. Explanations for the more frequent history of resuscitation in the elderly include the presence of organic heart disease with impairment of left or right ventricular function and differences in the management of these patients.

Adolescent↗
PubMed1993

Hemodynamic and hemorheologic determinants of left atrial spontaneous echo contrast and thrombus formation in patients with idiopathic dilated cardiomyopathy.

The purpose of the present study was to evaluate the specific role of hemorheologic and hemodynamic parameters for spontaneous echo contrast and thrombus formation in vivo. We therefore investigated the association between the presence of left atrial spontaneous echo contrast and thrombus formation by transesophageal echocardiography and multiple clinical, hemodynamic, and hemorheologic parameters in 70 patients with idiopathic dilated cardiomyopathy. Transesophageal echocardiography showed left atrial spontaneous echo contrast and left atrial thrombi in 33% and 19% of patients, respectively. Patients with left atrial spontaneous echo contrast had a lower cardiac index (2.1 +/- 0.9 versus 2.6 +/- 0.9 L/min/m2; p < 0.02), a lower left atrial (21 +/- 8 versus 38 +/- 10 cm/sec; p < 0.001) and left atrial appendage flow velocity (17 +/- 14 versus 39 +/- 13 cm/sec; p < 0.001), a larger left atrial diameter (53 +/- 6 versus 46 +/- 10 mm; p < 0.002), and more often presented with atrial fibrillation (62% versus 32%; p < 0.02). Plasma fibrinogen concentration (4.0 +/- 1.1 versus 3.5 +/- 0.7 gm/L; p < 0.02) and plasma viscosity (1.83 +/- 0.10 versus 1.76 +/- 0.15 mPa.sec; p < 0.05) were higher in patients with spontaneous echo contrast. Multivariate analysis revealed an association between the presence of spontaneous echo contrast and left atrial flow velocity p < 0.0001) and plasma viscosity (p < 0.01). In patients with left atrial (appendage) thrombus or a history of embolism, left atrial appendage flow velocity was lower (15.0 +/- 8.2 versus 29.6 +/- 14.5 cm/sec; p < 0.005) and spontaneous echo contrast was more frequently observed (52% versus 23%; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗