Successful AV Fistula Creation does not Lead to Higher Catheter Use: The Experience by the Northwest Renal Network 16 Vascular access Quality Improvement Program. Four Years follow-up

Background

In 2002, the Center for Medicare and Medicaid Services (CMS) required all 18 Renal Networks to participate in a Vascular Access Quality Improvement Program (QIP). The Northwest Renal Network (NWRN 16) chose to increase arteriovenous fistula (AVF) use. NWRN 16 hypothesized that strategies which targeted the improvement of AVF rate and the reduction of catheter use were the same. In December 2001, 44.2% of hemodialysis (HD) patients in the NWRN 16 received HD using an AVF which met the Dialysis Outcome Quality Initiative (K/DOQI) 40% AVF guideline for prevalent patients. However, 43% of HD facilities (2869 patients) had less than 40% of AVF and higher HD catheter rates than the average Network catheter rates (25.0 vs. 20.3%). To address the needs of underperforming facilities, NWRN 16 provided education and tools for their vascular access decision makers to promote AVF creation and catheter reduction.

Methods

In 2002, NWRN 16 sponsored four regional workshops targeted at nephrologists, vascular surgeons, HD nurses, and interventional radiologists.

Results

Percentage of AVFs in use in invited facilities increased from 31.3% pre-intervention to 56.2% at 4 yrs: 78% increase (99% confidence interval: 77.8% to 81.5%). Percentage of catheters increased from 25% to 25.8%: 3.2% change over 4 yrs (99% confidence interval: 2.5% to 4%).

Conclusion

The success of Network 16's AVF interventions demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, and innovative strategies to increase dramatically AVF use without substantial increase in catheter use.

Successful Multidisciplinary Interventions for Arterio-Venous Fistula Creation by the Pacific Northwest Renal Network 16 Vascular access Quality Improvement Program

Background

In December 2001, 44.2% of hemodialysis (HD) patients in the Northwest Renal Network (NWRN 16) received dialysis using an arteriovenous fistula (AVF). Substantial differences were noted in percentages of patients with AVF, ranging from 5% to 90% of the facility population, suggesting wide variation in physician practice patterns within the Network. To address the needs of facilities having <40% AVF, NWRN 16 provided education and tools for their vascular access decision-makers to promote AVF creation.

Methods

In 2002, the Network sponsored 4 regional workshops targeted to nephrologists, vascular surgeons, dialysis nurses, and interventional radiologists.

Results

46 facilities (43% of all Network facilities) had <40% AVF in use in December, 2001, dialyzing 2940 patients (Invited Units). Percent AVF in use in all the Invited Facilities increased from 31.3% pre-intervention to 39.8% at 1 year (p<0.001 vs pre) to 56.2% at four years: 79.8% increase in the prevalent AVF rate over a four-year period (95% confidence interval: 77.8% to 81.7%).

Conclusion

Low prevalent AVF rates in many NWRN 16 facilities may have resulted from differences in physician practice patterns. The success of Network 16 AVF Intervention demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, innovative strategies to increase AVF rates among dialysis patients.

Successful AV fistula creation does not lead to higher catheter use: the experience by the Northwest Renal Network 16 Vascular Access Quality Improvement Program. Four years follow-up

BACKGROUND

In 2002, the Center for Medicare and Medicaid Services (CMS) required all 18 Renal Networks to participate in a Vascular Access Quality Improvement Program (QIP). The Northwest Renal Network (NWRN 16) chose to increase arteriovenous fistula (AVF) use. NWRN 16 hypothesized that strategies which targeted the improvement of AVF rate and the reduction of catheter use were the same. In December 2001, 44.2% of hemodialysis (HD) patients in the NWRN 16 received HD using an AVF which met the Dialysis Outcome Quality Initiative (K/DOQI) 40% AVF guideline for prevalent patients. However, 43% of HD facilities (2869 patients) had less than 40% of AVF and higher HD catheter rates than the average Network catheter rates (25.0 vs. 20.3%). To address the needs of underperforming facilities, NWRN 16 provided education and tools for their vascular access decision makers to promote AVF creation and catheter reduction.

METHODS

In 2002, NWRN 16 sponsored four regional workshops targeted at nephrologists, vascular surgeons, HD nurses, and interventional radiologists.

RESULTS

Percentage of AVFs in use in invited facilities increased from 31.3% pre-intervention to 56.2% at 4 yrs: 78% increase (99% confidence interval: 77.8% to 81.5%). Percentage of catheters increased from 25% to 25.8%: 3.2% change over 4 yrs (99% confidence interval: 2.5% to 4%).

CONCLUSION

The success of Network 16's AVF interventions demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, and innovative strategies to increase dramatically AVF use without substantial increase in catheter use.

The ectopic pregnancy, a diagnostic and therapeutic challenge

The classic symptoms of ectopic pregnancy are secondary amenorrhoea, abdominal pain and vaginal haemorrhage, with a clinical picture of varying acuteness. It is among the commonest causes of maternal mortality during the first three months of pregnancy. In the majority of cases (95%) the pregnancy is tubal, but other sites are possible (cervical, corneal, ovarian, peritoneal). In the treatment of sterility or medically assisted reproduction, the risk of ectopic pregnancy should be borne in mind. The individual risk factors may be cumulative, particularly with a previous history of extrauterine pregnancy or tubal surgery (including sterilisations). pelvic post-inflammatory status (adhesions proved by coelioscopy) or presence of an intrauterine device. Diagnosis is based on serum beta-hCG concentration and transvaginal ultrasound. Laparoscopy is the treatment of choice for tubal pregnancies. The decision to perform salpingotomy depends on the presence/status of a contra lateral tube. In carefully selected cases local or intra-muscular administration of methotrexate allows conservative treatment, provided the patient does not present acute bleeding. It is also indicated where trophoblastic tissue persists after surgery, notably salpingostomy. and in non-tubal ectopic pregnancies. The latter are rare, however, and it is important to recognise them in view of the more serious complications.

Successful multidisciplinary interventions for arterio-venous fistula creation by the Pacific Northwest Renal Network 16 vascular access quality improvement program

BACKGROUND

In December 2001, 44.2% of hemodialysis (HD) patients in the Northwest Renal Network (NWRN 16) received dialysis using an arteriovenous fistula (AVF). Substantial differences were noted in percentages of patients with AVF, ranging from 5% to 90% of the facility population, suggesting wide variation in physician practice patterns within the Network. To address the needs of facilities having < 40% AVF, NWRN 16 provided education and tools for their vascular access decision-makers to promote AVF creation.

METHODS

In 2002, the Network sponsored 4 regional workshops targeted to nephrologists, vascular surgeons, dialysis nurses, and interventional radiologists.

RESULTS

46 facilities (43% of all Network facilities) had <40% AVF in use in December, 2001, dialyzing 2940 patients (Invited Units). Percent AVF in use in all the Invited Facilities increased from 31.3% pre-intervention to 39.8% at 1 year (p<0.001 vs pre) to 56.2% at four years: 79.8% increase in the prevalent AVF rate over a four-year period (95% confidence interval: 77.8% to 81.7%).

CONCLUSION

Low prevalent AVF rates in many NWRN 16 facilities may have resulted from differences in physician practice patterns. The success of Network 16 AVF Intervention demonstrates the effectiveness of Network education promoting multidisciplinary teamwork, innovative strategies to increase AVF rates among dialysis patients.

Automated Impedance Cardiography for Detecting Ischemic Left Ventricular Dysfunction during Exercise Testing

Automated impedance cardiography (ICG) is an attractive method for noninvasive hemodynamic evaluation. The objective of our study was to evaluate the feasibility and diagnostic value automated ICG in patients with suspected coronary artery disease (CAD). We measured stroke index (SI) and cardiac index (CI) in 65 patients with suspected CAD at rest and during bicycle exercise testing. All patients underwent subsequent cardiac catheterization including coronary angiography (CA). Depending on the results of CA, patients were divided into three groups, patients without significant CAD (group 0), single vessel disease (group 1) or multivessel disease (group 2-3). In a subset of 20 patients, automated ICG was compared to measurements of CI by the thermodilution (TD) method.

RESULTS

There were no significant differences in SI and CI at baseline between the three groups. At 75- and 100-watt exercise, patients in group 2-3 showed significantly lower mean values of SI and CI as compared to patients of group 0 and group 1 (all p < 0.05), indicating exercise-induced ischaemic left ventricular (LV) dysfunction. Three patients had to be excluded because of inappropriate quality of the ICG signals during exercise. Comparison of automated ICG with TD measurements of CI showed good correlations between both methods at rest (r = 0.73) and during exercise (r = 0.89-0.91).

CONCLUSIONS

We conclude that hemodynamic monitoring by automated ICG is both feasible and practical during exercise testing. Automated ICG can provide reliable and valuable additional diagnostic information on LV function during exercise which is helpful for selecting those patients for angiography who are likely to benefit from coronary interventions.

Paramagnetic oligonucleotides: contrast agents for magnetic resonance imaging with proton relaxation enhancement effects

An antisense paramagnetic oligonucleotide analogue targeted to a model macromolecular receptor (5S rRNA) was prepared. The paramagnetic agent's relaxivity (dependence of the relaxation rate on paramagnetic agent concentration) in the presence and absence of the macromolecular receptor was measured at 1.5 and 6.3 T. The relaxivity of the targeted agent increased specifically in the presence of the macromolecular receptor (16% at 6.3 T and 15% at 1.5 T). This effect was specific for a paramagnetic oligonucleotide targeted to the receptor and was larger than the relaxivity enhancement due simply to receptor-induced viscosity differences. Maximizing this relaxivity enhancement of tumor targeted paramagnetic oligonucleotides will aid in contrast agent development for magnetic resonance imaging.

[Dextrocardia and Poland syndrome in a 59-year-old patient]

Poland syndrome consists of unilateral absence of the sternal head of the pectoralis major muscle, ipsilateral symbrachydaktylia, and occasionally associated other malformations of the anterior chest wall, mammilla, and mamma. To our knowledge a simultaneous occurrence with dextrocardia was reported in seven patients. We report on an additional patient with this unusual coincidence. A 59-year old man showed mild symbrachydaktylia of the left hand and deformity of the left part of the anterior chest wall, both present since birth. We found an additional dextrocardia with situs solitus, d-loop, and correctly connected great arteries. Besides arterial hypertension there was no remarkable impairment of the patient's condition.

Diastolic intraventricular gradient in hypertrophic cardiomyopathy with apical hypertrophy

Patients with hypertrophic cardiomyopathy and additional diastolic flow abnormalities are relatively rare. This report describes a case of apical ventricular hypertrophy with complete systolic obstruction and holodiastolic intraventricular pressure gradient.

[Patent foramen ovale and platypnea after pneumonectomy]

Six months after a pneumonectomy for myeloma, which had preoperatively been indistinguishable from bronchial carcinoma, a 50-year-old man presented with shortage of breath, cyanosis and episodes of syncope on standing or walking, symptoms which improved on lying down (platypnea). On one occasion these symptoms necessitated controlled artificial ventilation, but even at an inspiratory oxygen saturation of 100%, blood gases only partially improved (pCO2 27 mm Hg, pO2 67 mm Hg, O2 saturation 93%). Right heart catheterization in recumbency revealed a right to left shunt at atrial level of 37% of systemic flow. Contrast medium injection into the inferior vena cava near the heart demonstrated cardiac displacement and rotation. Part of the inferior vena cava flow passed into the left atrium via a patent foramen ovale: it is likely that this shunt increased in the upright position. After surgical closure of the patent foramen ovale and partial relocation of the heart (with a vicryl net) the patient has now remained free of symptoms for 5 years.

[Conjunctival oxygen partial pressure, hemorheology and circulatory parameters in acute cerebral infarct before and following infusion of 6 percent low molecular hydroxyethyl starch]

A prospective clinical trial was performed on the effects of a three hour infusion of 500 ml 6% low-molecular-weight hydroxyethyl starch in patients with acute ischemic stroke. Hemorheology and conjunctival oxygen tension were found to be disturbed prior to treatment. After the infusion there was a marked improvement of the pertinent parameters, indicative of an increase in cerebral microcirculation and oxygen supply. Even 3 h later persistent significant effects were observed. The infusion was well tolerated. Blood pressure and cardiac index remained unchanged.

Morphological quantification and differentiation of left ventricular hypertrophy in hypertrophic cardiomyopathy and hypertensive heart disease. A two dimensional echocardiographic study

Differentiation between hypertrophic cardiomyopathy and hypertensive heart disease is a diagnostic challenge. M-mode echocardiography only permits assessment of hypertrophy in limited areas of the left ventricular wall. 2-D echocardiography allows visualization of most of the myocardium. To assess the reliability of conventional M-mode echocardiographic and 2-D echocardiographic criteria in patients with hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HY), 30 patients with hypertrophic cardiomyopathy and 30 patients with hypertension and severe cardiac hypertrophy were examined using M-mode and 2-D echocardiography. Although the M-mode echocardiographic features showed statistically significant differences between the mean values in the two groups, the degree of overlap made the differentiation of the individual patients difficult. The diagnostic sensitivity and specificity of classic echocardiographic features were assessed: ventricular septal thickness greater than or equal to 1.5 cm, 90% and 43% (sensitivity and specificity, respectively); ventricular septal thickness to posterior wall ratio greater than or equal to 1.5, 83% and 56%; cross-sectional area at papillary level greater than 21 cm2m-2, 80% and 73%; septal segment of the myocardial ring at papillary level greater than 6.5 cm2m-2, 80% and 87%; and the combined criteria of cross-sectional area at papillary level greater than 21 cm2m-2 and septal segment greater than 6.5 cm2m-2, 77% and 93%. Quantitative 2-D echocardiography is useful to differentiate patients with hypertrophic cardiomyopathy from those with secondary myocardial hypertrophy due to hypertension. Hypertrophic cardiomyopathy is characterized by a spectrum of different morphological patterns of hypertrophy. Patients with the predominant region of hypertrophy in the anterolateral free wall or the apical region of the left ventricle were not detected with our quantitative method. Patients with this type of hypertrophy are relatively rare in the western population.

Konjunktivaler Sauerstoffpartialdruck, Hämorheologie und Kreislaufparameter bei akutem zerebralem Insult vor und nach Infusion von 6prozentiger niedermolekularer Hydroxyäthylstärke

In einer prospektiven Studie untersuchten wir bei 12 Patienten mit akutem zerebralem Insult die Wirkung einer dreistündigen Infusion von 500 ml 6%iger niedermolekularer Hydroxyathylstarke. Die an-fangs gestörte Hämorheologie wurde deutlich verbessert, ebenso der anfangs erniedrigte konjunktivale Sauerstoffpartialdruck. Dies kann als Hinweis auf eine Steigerung der zerebralen Mikrozirkulation und Sauerstoffversorgung gewertet werden. Auch 3 h nach Infusionsende waren noch signifikante Veränderungen nachzuweisen. Die Volumen-belastung durch die Infusion wurde gut toleriert. Blutdruck und Herzminutenvolumen blieben stabil.

Ventricular function in cirrhosis and portasystemic shunt: a two-dimensional echocardiographic study

Cardiovascular alterations such as increased heart rate, high cardiac output, reduced systemic vascular resistance, and in most of the cases, increased contractility parameters have been recognized in patients with advanced liver disease. Some investigators define a cirrhotic cardiomyopathy as a hyperdynamic failure of the heart. Consequently, in patients with cirrhosis, the risk of developing further circulatory deterioration may be increased in situations which stress the cardiovascular system. After opening a portocaval shunt, it is expected that a large amount of blood will be distributed from the splanchnic to the pulmonary circulation and put a strain on the heart. This two-dimensional echocardiographic study was made in 30 patients with cirrhosis and in 20 patients who were chronically treated (range: 16 to 156 months) with portasystemic shunt for prevention of hemorrhage from esophageal variceal bleeding. Patients with portasystemic shunts revealed a change in hemodynamic pattern. There was a significant increase in the left ventricular end-diastolic volume index and also a slight increase in the left ventricular end-systolic index. Cardiac output remained high despite a significant decrease in heart rate due to an elevated left ventricular stroke volume index. The parameters of systolic ventricular performance were normal. In contrast to the acute opening of the portacaval shunt, the chronic shunt volume put no strain of clinical significance on the heart.

Effects of long-term treatment with 120 mg of sustained-release isosorbide dinitrate and 60 mg of sustained-release nifedipine on myocardial perfusion

Forty patients with coronary artery disease and scintigraphically proven myocardial ischemia were randomized into 2 groups receiving 4 weeks of treatment with either 120 mg of isosorbide dinitrate (ISDN) release or 60 mg of nifedipine release. Control exercise testing and myocardial scintigraphy were continued until anginal pains occurred, and repeated at identical individual workloads at the end of the 4 weeks of drug therapy. Myocardial scintigrams were evaluated by quantitative recording of counts in 60 segments/frame. Twenty patients in the ISDN group (group I) exhibited 47 significantly ischemic areas. The remaining 20 patients (group II), treated with nifedipine, had 50 ischemic areas before therapy. In the ischemic areas in group I, there was a mean difference of 30.9% between counts at rest and during exercise in the pretreatment period, and a difference of 18.1% after therapy (39.0%). In group II, the pretreatment difference was 28.8%, decreasing to 20.6% after therapy (17.8%). Both groups of patients were subsequently subdivided into 3 subsets: (1) significantly improved perfusion, (2) significant worsening, and (3) unchanged myocardial perfusion. Group I had 59.5% of areas with significant improvement and 10.6% of areas with significant worsening. In 29.7% of the areas, the findings were unchanged. Group II had improvement in 40% of areas, of significantly worsened areas in 6%, and unchanged areas in 54%, in both groups myocardial ischemia was reduced by therapy, but ISDN improved myocardial perfusion to a considerably greater extent than did nifedipine.

Hereditary angioedema and aortitis

A 28-year-old male with hereditary angioedema died of an extensive stroke. Autopsy revealed cicatricial aortitis with narrowing of the coronary ostia, myocardial infarctions, and a left ventricular mural thrombus. There was neither acute inflammation of the aorta nor systemic vasculitis. A possible association of the aortitis with the hereditary angioedema is discussed.

[Beat-by-beat validation of the Oxford Medilog 4500, a 24-hour long-term ECG system with real-time analysis]

We compared the annotation of the AHA and MIT databases beat-to-beat with the classification preformed by the microprocessor of a 24-hour ambulatory electrocardiographic device, based on real-time analysis. Sensitivity and positive predictive accuracy for QRS detection were 99.9% (99.9%) and 99.9% (99.8%) for the AHA database (MIT database respectively). Sensitivity and positive predictive accuracy were 99.1% (96.6%) and 98.3% (94.9%) for ventricular ectopic beats, 98.3% (91.8%) and 96.0% (63.0%) for couplets and 96.4% (74.2%) and 99.2% (41.1%) for salvoes. On 90% of the AHA tapes (MIT tapes) sensitivity and positive predictive accuracy were at least 93.8% (76.6%) and 92.7% (65.5%) for ventricular ectopic beats, at least 98.0% (96.3%) and 54.5% (0%) for couplets and at least 100% (66.6%) and 100% (0%) for salvoes. A sensitivity of 100% was achieved for ventricular ectopic beats on 56% (45%), for couplets on 90% (82%) and for salvoes on 95% (84%) of the AHA tapes (MIT tapes). A positive predictive accuracy of 100% was achieved for ventricular ectopic beats on 49% (52%), for couplets on 76% (61%) and for salvoes on 97% (75%) of the AHA tapes (MIT tapes). Real-time analysis of the Oxford Medilog 4500 proved sufficient for QRS detection and classification of ventricular ectopic beats. The quantification of frequent couplets and salvoes was sufficient, too. Sporadic false-positive detections of complex ventricular ectopic beats produced the false Lown grade IVA/IVB on 10% of the tapes as a consequence. The final computer report must hence be edited by a physician.

Malignant ventricular tachyarrhythmias in association with propafenone treatment

During treatment with the class Ic antiarrhythmic agent propafenone, the drug appeared to cause malignant ventricular tachyarrhythmias in five patients. Sudden cardiac death occurred in two of them. Three patients exhibited a transition from non-self-terminating ventricular tachycardia to ventricular fibrillation. In the other two patients electrocardiography during syncope revealed ventricular fibrillation. The observed malignant arrhythmias occurred within the first three days of treatment for chronic complex ventricular ectopic activity. Two of the five patients had markedly impaired left ventricular function. All patients received digoxin and low dose diuretic therapy. In contrast to drug induced arrhythmias encountered with other type I antiarrhythmic agents, the proarrhythmic effects of propafenone were not associated with marked QT prolongation. QRS duration was only slightly affected.

Unusual mechanism of PR interval variation and nonreentrant supraventricular tachycardia as manifestation of simultaneous anterograde fast and slow conduction through dual atrioventricular nodal pathways

Noninvasive recordings in a 69-year-old woman showed two distinct PR intervals of about 0.21 and 0.58 s, suggestive of dual AV nodal conduction. Various unusual mechanisms of transition from short to long and from long to short conduction intervals and phenomena of concealed conduction were due to the presence of two functionally separated intranodal pathways. Refractoriness of the slow pathway was associated with bradycardia. Episodes of tachycardia exhibited a one-to-two relationship between P-waves and ventricular activations as a consequence of simultaneous anterograde fast and slow conduction leading to double ventricular responses to single P-waves.

[Tachycardias caused by double ventricular responses and unusual atrioventrio-ventricular relations in linear dissociation of the AV node]

Noninvasive recordings in a 69-year-old woman showed phasic shifts between two distinct PR intervals of about 0.21 and 0.58 s suggestive of dual AV nodal conduction in the presence of two intranodal pathways. Episodes of tachycardia exhibited a one to two relationship between P waves and QRS complexes, with the same short and long PR intervals interpreted as simultaneous anterograde fast and slow conduction via the two AV nodal pathways, leading to a double ventricular response to single P waves. Various mechanisms of transition from short to long or long to short conduction times and concealed conduction phenomena could be demonstrated supporting the concept of two functionally separated intranodal pathways.

[Lorcainide in stable ventricular extrasystole. A double-blind study with 48-hour continuous ECG recording]

In a randomized double-blind cross-over trial, the effectiveness of lorcainide at a dosage of three times 100 mg/d by mouth was compared with that of a placebo for the treatment of subjectively disturbing stable ventricular extrasystoles (VES), using 48-hour continuous ECG monitoring. In 11 of 20 patients there was a regression in the VES rate to under 5%, in other 3 patients to under 50% of the initial values. Continuing the treatment, good therapeutic effect was still demonstrable 14 and 28 days later. However, only three patients had no side-effects. The others had sleep disturbances, hot flushes, sweating, restlessness, anxiety, dizziness, hallucinations and gastrointestinal symptoms. Lorcainide thus has a good anti-arrhythmic effect but, because of its side-effects, it should be used only in special circumstances.

[Mechanically-induced intraventricular block caused by a right-heart floating catheter--frequency and electrophysiologic findings]

During the course of 2,434 right heart catheterizations with 2,019 floating 3F Grandjean catheters and 415 5F Swan-Ganz catheters we observed 7 patients (0.3%) with catheter-induced infranodal conduction impairment: right bundle branch block (RBBB) in 3 patients, left anterior fascicular block (LAFB) and subsequent RBBB in 1 patient, and complete heart block in 3 patients with pre-existing left bundle branch block (LBBB). There was no apparent difference regarding the incidence of blocks between the two types of catheters. Three patients (one with LAFB + RBBB and two with LBBB) underwent electrophysiologic studies. All three patients exhibited a prolongation of the HV-interval due to coexisting pathologic changes of the right bundle. LBBB patterns disappeared during distal His bundle pacing in two patients, indicating a proximal site of block and suggesting incomplete involvement of the right bundle. Additional mechanical trauma, probably in this region, produced the blocks. Thus, use of balloon tipped or flexible catheters does not provide complete protection against transient lesions of the conduction system.

Effects of flecainide on electrophysiological properties of accessory pathways in the Wolff-Parkinson-White syndrome

The effect of flecainide in 12 patients with the Wolff-Parkinson-White syndrome was analyzed with respect to the anterograde and retrograde conduction properties of the accessory pathway, the modes of initiation and termination of circus movement tachycardias, and the ventricular response during induced atrial fibrillation. The principal effect of this drug was to depress both anterograde and retrograde conduction of the accessory pathway. In 8/9 cases circus movement tachycardia was terminated by prolongation of the retrograde effective refractory period of the accessory pathway. Flecainide increased the shortest and the mean cycle length during induced atrial fibrillation. It is concluded that the drug may be of potential benefit in patients with paroxysmal supraventricular tachycardias in patients with the Wolff-Parkinson-White syndrome.

[Hemodynamic consequences of suddenly abolished atrial contraction]

The effects of several modes of stimulation (right ventricular pacing during sinus rhythm, right ventricular pacing during induced atrial fibrillation, and atrioventricular (AV) sequential pacing with an AV delay of 130 msec) on blood pressure and cardiac output were investigated in 10 patients with normal left ventricular function. The stimulation rates were 110, 140, and 170/min for each stimulation mode. There were no significant differences between ventricular pacing in sinus rhythm and ventricular pacing in atrial fibrillation as regards blood pressure and cardiac output. Ventricular stimulation during atrial fibrillation resulted in a significant fall in systolic blood pressure (84%, p less than 0.05) even at a rate of 140/min, whereas in AV-sequential pacing systolic blood pressure only fell to 87% of the baseline value at a rate of 170/min. A significant decrease in cardiac output occurred at rates of 140/min ventricular pacing during atrial fibrillation and at rates of 170/min with AV-sequential pacing. The results underline the importance of active ventricular filling in tachycardia. There were no significant differences in the measured parameters when ventricular pacing with AV-dissociation was compared with ventricular pacing at identical rates during atrial fibrillation.

[Heart rate reduction in atrial fibrillation with a rapid ventricular response by Gallopamil, a Ca-antagonist (author's transl)]

20 patients with atrial fibrillation and rapid ventricular response were treated with the new calcium-antagonist Gallopamil. The effects on heart rate were evaluated by Holter-monitoring. A significant decrease of heart rate with a duration of 10 hours was found in 10 patients after acute oral administration of 100 mg Gallopamil. In 5 patients a regularization of the ventricular response was observed, suggesting an AV junctional escape rhythm during AV nodal block. However, no relevant bradycardia was seen. The maximal decrease of heart rate was seen 2 to 4 hours after application. Oral administration of 3 times 50 mg Gallopamil daily decreased heart rate after a treatment period of 1 week to about 79% of its control values. This effect started 1 hour after application of the first dose in the morning and it lasted for 7 hours after the evening dose.

Sleep patterns in cat induced by gammahydroxybutyric acid

Intravenous injections of gammahydroxybutyric acid (GHBA) (150-200 mg/kg) induce desynchronized sleep (DS) in the cat. This was shown by recording the EEG, eye-movements, the neck EMG, heart-rate and arterial pressure. The decreases in arterial pressure were not different from those recorded during naturally occurring DS. GHBA, given at doses above 200 mg/kg induced anaesthesia, during which arterial pressure was elevated. At the end of GHBA-induced sleep or anaesthesia there was a stage during which the animals were ataxic. The EEG showed a hypersynchronous spike pattern and arterial pressure was markedly elevated.