Venovenous extracorporeal membrane oxygenation for COVID-19 associated severe respiratory failure: Case series from a Hungarian tertiary centre

INTRODUCTION

Venovenous extracorporeal membrane oxygenation (V-V ECMO) is recommended for the support of patients with severe COVID-19 associated severe respiratory failure (SRF). We report the characteristics and outcome of COVID-19 patients supported with V-V ECMO in a Hungarian centre.

METHODS

We retrospectively collected data on all patients admitted with proven SARS CoV-2 infection who received V-V ECMO support between March 2021 and May 2022.

RESULTS

Eighteen patients were placed on ECMO during this period, (5 women, age (mean ± SD) 44 ± 10 years, APACHE II score (median (interquartile range)) 12 (10-14.5)). Before ECMO support, they had been hospitalised for 6 (4-11) days. Fifteen patients received noninvasive ventilation for 4 (2-8) days, two patients had high flow nasal oxygen therapy, for one day each. They had already been intubated for 2.5 (1-6) days. Prone position was applied in 15 cases. On the day before ECMO initiation the Lung Injury Score was 3.25 (3-3.26), the PaO2/FiO2 ratio was 71 ± 19 mmHg. The duration of V-V ECMO support was 26 ± 20 days, and the longest run lasted 70 days. Patients were mechanically ventilated for 34 ± 23 days. The intensive care unit (ICU) and the hospital length of stay were 40 ± 28 days and 45 ± 31 days, respectively. Eleven patients were successfully weaned from ECMO. The ICU survival rate was 56%, the in-hospital survival was 50%. All patients who were discharged from hospital reported a good health-related quality of life Rankin score (0-2) at the 5-16 months follow-up.

CONCLUSIONS

During the last three waves of the COVID-19 pandemic, we achieved a 56% ICU and a 50% hospital survival rate at our low volume centre.

A „nyakon fogott” syncope esete

A carotis sinus syncope a carotismasszázsra adott túlzott mértékű válasz, melyet markáns vérnyomásesés és változó mértékű bradycardia, esetenként másodpercekig tartó asystolia jellemez, s ezek összességükben rövid eszméletvesztéshez vezetnek. A carotissyncopével rokonságban áll az a helyzet, amikor parapharyngealis térfoglaló folyamat manifesztálódik reflexes eredetű keringési instabilitás formájában. Esetismertetésünkben egy olyan beteget mutatunk be, akinél az ájulás keringési komponensei különösen jól dokumentáltak. Az eset felhívja a figyelmet az ájulás és a pulzus nélküli elektromos aktivitás tünetei közti esetleges átfedésre. Bemutatunk egy egyszerű megoldást is a nyak átmeneti immobilizálására s ezen keresztül az ijesztő klinikai kép kontrollálására. Orv Hetil. 2022; 163(44): 1763–1765.

The Feasibility of Baroreflex Sensitivity Measurements in Heart Failure Subjects: The Role of Slow-patterned Breathing

INTRODUCTION

Increased muscle sympathetic nerve activity (MSNA) indicates an adverse outcome in heart failure. Decreased baroreflex modulation of MSNA is well known feature of the disease. The determinability of cardiovagal baroreflex sensitivity (BRS) in heart failure is low, however, the determinability of sympathetic BRS is not known.

METHODS

We have assessed the spontaneous, MSNA burst incidence-based baroreflex index (BRSsymp) in 33 stable heart failure patients and in 10 healthy controls using the traditional r≥0.5 cut-off for acceptable individual diastolic pressure-burst incidence slopes, and also a more stringent r≥0.7 cut-off. We have also assessed the influence of 6/min breathing.

RESULTS

The determinability of BRSsymp in heart failure patients was 64% during spontaneous breathing with r≥0.5 cut-off, and 39% using the r≥0.7 cut-off. The determinability of these indices further decreased during 6/min breathing, dropping to 29% with the r≥0.7 cut-off. In contrast, the determinability of the cardiovagal BRS indices increased significantly with 6/min breathing (from 24% to 66%; p<0.001). Patients who still had determinable BRSsymp at the r≥0.7 cut-off had a significantly lower baseline burst incidence than those with an undeterminable index (70±14 vs.89±10 burst/100 cycles; p<0.002). Neither the 6/min breathing, nor the r≥0.7 cut-off limit influenced the high availability of BRSsymp in healthy subjects.

CONCLUSION

The determinability of BRSsymp in heart failure patients is limited, especially with the 0.7 limit for correlation. Undeterminable BRSsymp in patients is associated with higher sympathetic activity. 6/min breathing improves the determinability of cardiovagal BRS indices, but not that of BRSsymp. This article is protected by copyright. All rights reserved.

Sympathetic activation in heart failure with reduced and mildly reduced ejection fraction: the role of aetiology

Aim

While sympathetic overactivity in heart failure (HF) with reduced ejection fraction (HFrEF; EF < 40%) is well‐documented, it is ill‐defined in patients with mildly reduced EF (HFmrEF; EF 40–49%). Furthermore, the significance of ischaemic versus non‐ischaemic aetiology in sympathetic activation is also unclear and has yet to be studied in HF. Our goal was to compare muscle sympathetic nerve activity (MSNA) in HFmrEF and HFrEF patients and in healthy subjects, as well as to elucidate the influence of the underlying disease.

Methods and results

Twenty‐three HFrEF (age 58 ± 10 years), 33 HFmrEF patients (age 61 ± 10 years), including 11 subjects with non‐ischaemic cardiomyopathy in each HF groups and 10 healthy controls (age 55 ± 10 years), were studied. MSNA—detected by peroneal microneurography, continuous arterial pressure, and ECG—was recorded. MSNA frequency (burst/min) and incidence (burst/100 cycles) were calculated. Association with the patients' characteristics were assessed, and aetiology‐based comparisons were performed. Burst frequency demonstrated a significant stepwise increase in both HFmrEF (41 ± 11 burst/min) and HFrEF (58 ± 17 burst/min, P < 0.001) patients as compared with controls (27 ± 9; P < 0.001 for both HF groups). Similarly, burst incidences were 66 ± 17, 82 ± 15, and 36 ± 10 burst/100 cycles in HFmrEF, HFrEF patients, and in healthy controls, respectively (P < 0.001 for all). Burst frequencies in HF patients showed significant correlation with NT‐proBNP levels, and significant inverse correlations with the subjects' mean RR intervals, stroke volumes, pulse pressures, and EF.

Conclusions

Muscle sympathetic nerve activity parameters indicated significant sympathetic activation in both HFmrEF and HFrEF patients as compared with healthy controls with no difference in relation to ischaemic versus non‐ischaemic aetiology.

Tachycardia dependent early repolarisation pattern in subarachnoid haemorrhage related takotsubo syndrome

We present a case of a patient who suffered subarachnoid haemorrhage (SAH), complicated by takotsubo syndrome, paroxysmal atrial fibrillation and ECG repolarisation abnormality, compatible with Brugada phenocopy. The early repolarisation morphology showed a paradox association with the cardiac cycle length; a relationship not yet documented in SAH. Our observation also sheds light on the genesis of the "spiked helmet" ECG sign.

Extracorporeal membrane oxygenation in intensive care unit

Összefoglaló. Az extracorporalis membránoxigenizációt egyre gyakrabban alkalmazzák világszerte refrakter légzési és/vagy keringési elégtelenség kezelésében. Intézetünkben 2015-ben kezdtük meg a program előkészítését és felépítését. Célunk az extracorporalis membránoxigenizációs kezelés élettani alapjainak rövid ismertetése, különös tekintettel a venovenosus konfigurációra, és az eddig kezelt eseteink eredményeinek összefoglalása. Az irodalom szisztematikus áttekintése és a kezelt esetek adatainak retrospektív értékelése voltak a módszereink. 2016 óta összesen 14 beteg esetében használtunk extracorporalis membránoxigenizációt (8 férfi, 6 nő, életkor 51 ± 15 év, APACHE II. score 24 ± 7). Az indikáció 9 esetben súlyos refrakter hypoxaemiás légzési elégtelenség, 1 esetben tracheooesophagealis fistula és légzési elégtelenség, 1 esetben műtét alatti támogatás tervezett trachearekonstrukció során és 3 beteg esetében refrakter cardiogen shock volt. Az extracorporalis membránoxigenizáció 11 betegben a légzés, 3 betegben a keringés támogatását szolgálta, 13 venovenosus, 1 venoarteriosus konfigurációban. Az extracorporalis támogatás ideje légzéstámogatás esetében 14 ± 6 nap, a cardialis támogatások esetében 5 ± 4 nap volt. Az intenzív osztályos ápolási idő 27 ± 13, illetve 21 ± 17 nap volt a két betegcsoportban. 9 beteget jó funkcionális állapotban bocsátottunk el, 5 beteg halt meg osztályunkon, további 3 később a kórházi bennfekvés során. Az extracorporalis membránoxigenizációs program regionális centrumokban Magyarországon is megvalósítható. A nemzetközi ajánlások, oktatási módszerek alkalmazásával a nemzetközi irodalomban közölt túlélési eredményekhez hasonló eredmények érhetők el hazánkban is. Orv Hetil. 2021; 162(11): 425-431. Summary. Extracorporeal membrane oxygenisation is commonly used worldwide for refractory respiratory and circulatory failure. We started to organise the introduction of this therapeutic modality in 2015. Our aim is to give a short review about extracorporeal life support, especially veno-venous extracorporeal membrane oxygenation, and to present our first results. We provide a systematic review of the currently available literature and a summary of our first treatments. As of 2016, we supported 14 patients with extracorporeal membrane oxygenisation (8 men, age 51 ± 15 years, APACHE II score 24 ± 7). The indications were refractory hypoxaemic respiratory failure in 9, tracheo-oesophageal fistula and respiratory failure in 1, support during surgery for planned tracheal reconstruction in 1, and refractory cardiogenic shock in 3 patients. We provided respiratory support in 11, circulatory support in 3 cases, with 13 veno-venous and 1 veno-arterial configuration. The support lasted for 14 ± 6 days in respiratory, and for 5 ± 4 days in cardiac cases. Intensive care length of stay was 27 ± 13 and 21 ± 17 days in the two patient groups. We discharged 9 patients in good functional state, 5 patients died during intensive care and further 3 later, during the hospital stay. Our results show that the implementation of an extracoporeal membrane oxygenation program is feasible in Hungarian tertiary centers. In line with international recommendations and adapting international training courses, the survival is very similar to that reported in the literature. Orv Hetil. 2021; 162(11): 425-431.

Cardiovagal and sympathetic baroreflex regulation in heart failure

Összefoglaló. Bevezetés: Az artériás baroreflex-érzékenységi (BRS-) indexek egységnyi nyomásváltozásra adott élettani válaszokat írnak le. Az RR-intervallum gyors válaszait a cardiovagalis BRS-indexekkel, a vasomotorválaszokat az izom szimpatikus idegi aktivitás (MSNA) válaszain alapuló szimpatikus-BRS-indexekkel jellemezzük. Szívelégtelenségben kórosan csökkent értékeik kedvezőtlen kimenetelt jeleznek. Betegek és módszerek: A BRS-indexek meghatározhatóságát 52, szívelégtelenségben szenvedő betegben (kor: 59 ± 10 év; EF: 37 ± 11%) és 11, kor szerint illesztett egészséges önkéntesben vizsgáltuk. EKG- és vérnyomásfelvételekből három cardiovagalis BRS-indexet számítottunk; a növekvő, illetve csökkenő spontán szekvenciák módszerén alapuló up-BRS-t és down-BRS-t, továbbá az alacsony frekvenciatartomány-beli 'cross-spectralis ' indexet, az LF-alfát. Egy perifériás ideg (nervus peroneus) perkután punkciójával detektáltuk az MSNA szimpatikus csúcs incidenciáját (csúcs/100 szívciklus), s ezt korreláltattuk a diastolés nyomás 3 Hgmm sávokba rendezett értékeivel. Így nyertük a szimpatikus BRS jellemzőit, a BRSSY-incidencia-értékeket. Eredmények: Az up- és down-BRS-szekvenciák csak a betegek 19%-ában voltak meghatározhatók, az LF-alfa a 69%-ukban. Azok, akiknél cardiovagalis BRS nem volt meghatározható, szignifikánsan csökkent RR-intervallum-ingadozást és magasabb NT-proBNP-értékeket mutattak. A meghatározható cardiovagalis BRS-indexek nem különítették el a betegeket és a kontrollszemélyeket. A BRSSY-incidencia-érték 58%-ban állt rendelkezésre, s csakúgy, mint maga a "csúcs" incidencia, jól elkülönítette a betegeket és az önkénteseket. A hiányzó baroreflexérték a magas "csúcs" incidenciával állt összefüggésben. Következtetés: A cardiovagalis BRS-értékek csak korlátozottan alkalmasak egészséges önkéntesek és szívelégtelen betegek elkülönítésére, a meghatározhatatlan értékek súlyosabb betegségre utalnak. A BRSSY-incidencia elkülöníti az egészséges és a beteg csoportokat; a hiányzó érték a fokozott szimpatikus aktivitással áll összefüggésben. Orv Hetil. 2021; 162(3): 91-98.

SUMMARY

INTRODUCTION

Arterial baroreflex sensitivity (BRS) is characterized by the magnitude of physiological responses to arterial pressure changes. Rapid RR interval responses are quantified by cardiovagal BRS parameters, sympathetic responses could be assessed by changes in muscle sympathetic nerve activity (MSNA). Abnormal indices in heart failure are associated with poor outcome.

PATIENTS AND METHODS

52, heart failure patients (age 59 ± 10 years, EF 37 ± 11%), and 11, age-matched healthy volunteers were studied. From ECG and arterial pressure recordings up-BRS and down-BRS values were determined using the method of spontaneous sequences. The low frequency cross-spectral gain, the LF alpha was also determined. Percutaneous puncture of the peroneal nerves allowed determination of MSNA burst incidence (burst/100 cycles), which was correlated to corresponding diastolic pressure bins of 3 mmHg, yielding a sympathetic BRS, the BRSSY-incidence.

RESULTS

Up- and down-BRS could be calculated in 19% of the patients, LF alpha was determined in 69%. Those with missing cardiovagal BRS values showed diminished RR interval variation, and higher levels of NT-proBNP. The measurable cardiovagal BRS indices did not separate patients and healthy volunteers. BRSSY-incidence could be determined in 58% of the patients. The sympathetic gain as well as the burst incidence differed significantly between patients and healthy volunteers. Missing BRSSY-incidence was associated with higher burst incidence.

CONCLUSION

Cardiovagal BRS indices have limited value in differentiating healthy and heart failure subjects. Incalculable values among patients indicate more severe disease state. BRSSY-incidence does separate healthy and diseased population, the missing BRSSY-incidence values are related to increased sympathetic activity. Orv Hetil. 2021; 162(3): 91-98.

Paradoxical pulse

For thousands of years, palpation of the peripheral pulse was the most important source of information for the physicians about their patients' circulation. The rate, amplitude, and pattern of the pulse served as a basis of amazing observations, although several of them have been also confirmed and substantiated by modern medicine. One of the classical signs is "paradoxical pulse" (PP), which signals potentially life-threatening conditions with various mechanisms in certain diseases. In our review, we demonstrate the pathophysiological bases of PP, and show the equivalents of this sign provided by modern medical equipments. Orv Hetil. 2020; 161(38): 1629-1635.

Theory and history of the study of muscle sympathetic nerve activity

Heart failure is a rapidly growing epidemic in developed countries. It has been well documented that heart failure is associated with abnormal neurohumoral activation. The autonomic regulation is characterized by decreased parasympathetic and elevated sympathetic activity. While the cardiovagal activity could be easily assessed by various heart rate variability parameters, markers of the sympathetic activity are not readily available. Percutaneous insertion of microelectrodes in a peripheral nerve allows recording of the muscle sympathetic vasomotor nerve activity (MSNA). MSNA shows good correlation with the cardiac sympathetic activity, and also with the levels of circulating catecholamines. Besides determination of the baseline sympathetic activity, rapid sympathetic responses to various stimuli can be also described by changes of MSNA. Elevated MSNA has been documented in several diseases, including hypertension, obesity, myocardial ischemia and renal failure. In heart failure, the elevated MSNA is well correlated to the clinical severity of the patient's conditions, and serves as a prognostic marker of mortality. In our paper, we give a short account of the history of MSNA studies, describe its physiological background and clinical relevance with special regard to heart failure. Orv Hetil. 2020; 161(29): 1190-1199.

[Coronary angiography and percutaneous intervention after resuscitation]

Out-of-hospital cardiac arrest (OHCA) presents a great challenge for the health care systems even in the highly developed countries. For several decades, our greatest efforts have been directed toward the improvement of the prehospital management, including promotion of lay resuscitation and deployment of public access automated defibrillators. Recently, the importance of the hospital phase of the OHCA-management has been also emphasized. Attention has been paid to targeted temperature management and also to early coronary intervention. For those patients who present with ST-elevation on their post-resuscitation ECG, our approach is straightforward: urgent coronary angiography is indicated. The optimal management of those survivors of OHCA who present without ST-elevation is, however, still debated. Although up to 30% of these subjects also suffer from acute occlusive epicardial coronary disease, the clear benefit of urgent coronary angiography for the whole group is yet to be documented. Several large-scale randomized studies are under way to resolve this question. In our present review we detail the above controversies and outline the future directions. Orv Hetil. 2019; 160(46): 1826-1831.

P326Characteristic of sympathetic nerve activity in two subgroups of patients with heart failure (HFrEF and HFmrEF)

Introduction

Sympathetic overactivity is a well documented in severe heart failure (HF) with reduced ejection fraction (HFrEF). The European Society of Cardiology has recently introduced a new HF category, i.e. HF with mid-range ejection fraction (HFmrEF), characterized by left ventricular EF of 40–49%. The sympathetic regulation in this new category has not been thoroughly described.

Aims

Characterization of the sympathetic regulation in patients with HFmrEF compared with data obtained from HFrEF patients and healthy volunteers.

Method

14 HFrEF patients, 22 HFmrEF patients and 10 control subjects were enrolled (Table 1). Muscle sympathetic nerve activity, (MSNA) was recorded in the superficial peroneal nerve by microneurography, and processed by the Nerve Traffic Analyzer System (Model 662C-3, Iowa). Continuous ECG and non-invasive blood pressure (Finapres 2300) were digitized online (500 Hz/channel). Sympathetic burst frequency (bursts/minute) and burst incidence (bursts/100 heartbeats) were determined. The 6 min walking distances (6MWD) and NT proBNP levels in the HF subgroups were also assessed.

Results

Both burst frequency and incidence were significantly elevated in the HF subgroups compared to controls, and significant differences were also seen between the HFrEF and HFmrEF groups. The sympathetic burst activity in the HF populations significantly correlated with the NT proBNP level (R=0.53, p=0.003) and inversely correlated with the ejection fraction (R=−0.38, p=0.03).

Table 1. Results EF <40% EF: 40–49% Healthy control group (HC) p p p (n=14) (n=22) (n=10) EF <40% vs. EF: 40–49% EF <40% vs. HC EF: 40–49% vs. HC NYHA   I–II 8 21 − − − −   III–IV 6 1 − − − − Age 58.36±12.31 62.23±9.74 52.44±10.41 0.302 0.247 0.019 BMI 29.65±3.77 29.84±4.19 − 0.895 − − NT proBNP [ng/L] 1574.75±1415.06 300.20±247.35 − 0.002 − − 6MWT [m] 476.88±63.53 496.53±76.59 − 0.503 − − EF [%] 44.47±3.34 26.78±8.58 − − − − Baseline   burst/min 59.29±14.18 39.55±9.48 25.78±8.47 <0.001 <0.001 0.001   burst/100 84.64±12.63 65.68±15.48 35.78±11.27 0.001 <0.001 <0.001

Conclusion

Sympathetic activity is elevated in heart failure as compared to healthy controls. In patients with HFrEF both parameters of sympathetic activity were significantly higher as compared to patients with HFmrEF.

Acknowledgement/Funding

The work is supported by the GINOP-2.3.2-15-2016-00043 project. The project is co-financed by the EU and the European Regional Development Fund

Mean arterial pressure targeted fluid resuscitation may lead to fluid overload: A bleeding-resuscitation animal experiment

Introduction

Fluid resuscitation is the cornerstone of treatment in hemorrhagic shock. Despite increasing doubts, several guidelines recommend to maintain mean arterial pressure (MAP) >65 mmHg as the most frequent indication of fluid therapy. Our aim was to investigate the effects of a MAP-guided management in a bleeding-resuscitation animal experiment.

Materials and methods

After anesthesia and instrumentation (t_bsl) animals were bled till the initial stroke volume index dropped by 50% (t₀). Fluid replacement was performed in 4 equivalent steps (t_1-4) with balanced crystalloid solution to reach the baseline values of MAP. Invasive hemodynamic measurements and blood gas analyses were performed after each step.

Results

Mean arterial pressure dropped from t_bsl to t₀ (114±11 vs 76.9±16.9 mmHg, p<0.001) and returned to baseline by t₄ (101.4±14.4 mmHg). From t_bsl-t₀ stroke volume index (SVI), cardiac index (CI) decreased (SVI: 40±8.6 vs 19.3±3.6 ml/m², p<0.001; CI: 3.4±0.3 vs 1.9±0.3 l/min/m², p<0.001), pulse pressure variation (PPV) increased (13.2±4.3 vs 22.1±4.3%, p<0.001). There was a decrease in oxygen delivery (464±45 vs 246±26.9 ml/min, p<0.001), central venous oxygen saturation (82.8±5.4 vs 53.6±12.1%, p<0.001) and increase in lactate levels (1.6±0.4 vs 3.5±1.6 mmol/l, p<0.005). SVI, CI and PPV returned to their initial values by t₂. To normalize MAP fluid therapy had to be continued till t₄, with the total infused volume of 4.5±0.8 l.

Conclusion

In the current experiment bleeding led to hemorrhagic shock, while MAP remained higher than 65 mmHg. Furthermore, MAP was unable to indicate the normalization of SVI, CI and PPV that resulted in unnecessary fluid administration. Our data give further evidence that MAP may be an inappropriate parameter to follow during fluid resuscitation.

Noninvasive continuous arterial pressure measurements in the assessment of acute, severe central hypovolemia

Acute, severe hypovolemia is a medical emergency. Traditional vital sign parameters allow no optimal triage. High predictive power of finger plethysmography-based stroke volume (SV) and pulse pressure (PP) was recently suggested. To assess the performance of the PP and SV parameters, lower body negative pressure of -40 mmHg, than -60 mmHg - corresponding to moderate and severe central hypovolemia - was applied in 22 healthy males (age 35 ± 7 years). Slow breathing induced fluctuations in the above indices, characterized by stroke volume variability (SVV), and pulse pressure variability (PPV), were assessed. Responses in heart rate (HR) and shock index (SI) were also studied. Discriminative capacity of these parameters was characterized by the area under the ROC (receiver operating characteristic) curves (AUC).

RESULTS

In comparison of baseline to severe central hypovolemia SV, PP, HR, and SI showed good discriminating capacity (AUC 99%, 88%, 87%, and 93%, respectively). The discriminating capacity of SVV and PPV was poor (77% and 70%, respectively). In comparison of moderate and severe hypovolemia, the discriminating capacity of the studied parameters was uniformly limited.

CONCLUSIONS

Plethysmography-based SV and PP parameters can be used to detect acute severe volume loss. Sensitive parameters discriminating moderate and severe central hypovolemia are still lacking.

Hemodynamic effects of slow breathing: does the pattern matter beyond the rate?

PURPOSE

Patterned breathing allows standardized serial measurements of heart rate variability and baroreflex indices. The slow breathing augments these parameters, and regular exercises, including yoga breathing practices with even respiratory rates have long-term beneficial effects in cardiovascular diseases. The role of temporization of breathing phases, i.e. the ratio of expiration to inspiration, is not known. In order to characterize the hemodynamic and autonomic responses during varying breathing phases 27 volunteers performed three short breathing sessions at 6/minutes frequency with 5:5, 3:7 and 7:3 inspiration expiration ratios.

RESULTS

The immediate responses in arterial pressure and heart rate were negligible. The time domain parameters of heart rate variability (SDRR, PNN50,RMSSD) increased significantly with patterned breathing. So did the spontaneous baroreflex gain of increasing sequences (up-BRS, from 12 ± 7 to 17 ± 10 ms/mmHg, p < 0.05), and the cross-spectral low frequency gain, the LFalpha (from 11 ± 7 to 15 ± 7 ms/mmHg, p < 0.05). None of these parameters differed significantly from each other while using any of tested inspiratory-expiratory patterns.

CONCLUSION

The major determinant of autonomic responses induced by slow patterned breathing is the breathing rate itself. From our observations, it follows that slow breathing exercises performed either with diagnostic or therapeutic purpose could be simplified, allowing more extensive investigations.

Non-invasive detection of hypovolemia or fluid responsiveness in spontaneously breathing subjects

Background

In the assessment of hypovolemia the value of functional hemodynamic monitoring during spontaneous breathing is debated. The aim of our study was to investigate in spontaneously breathing subjects the changes in hemodynamic parameters during graded central hypovolemia and to test whether slow patterned breathing improved the discriminative value of stroke volume (SV), pulse pressure (PP), and their variations (SVV, PPV). In addition, we tested the alterations in labial microcirculation.

Methods

20 healthy volunteers participated in our study. Central hypovolemia was induced by lower body negative pressure (LBNP). Continuous signals of ECG, non-invasive blood pressure and central venous pressure were recorded. During baseline and each stage of LBNP the labial microcirculation was investigated by orthogonal polarization spectral imaging, 3 minute periods of patterned breathing at 6 and 15/min respiratory rate were performed, and central venous blood gas analysis was done. Data from baseline and those of different LBNP levels were compared by analysis of variance and those of different breathing rates by t-test. Finally, we performed ROC analysis to assess the discriminative values of SV, PP, SVV and PPV.

Results

Moderate central hypovolemia induced by LBNP caused significant, clinically relevant falls in PP (p < 0.05) and SV and central venous oxygen saturation (ScvO₂) (p < 0.001). The proportion of perfused vessels (p < 0.001) and microvascular flow index decreased (p < 0.05). PPV increased (p < 0.001), however the magnitude of fluctuations was greater during slow patterned breathing (p < 0.001). SVV increased only during slow patterned breathing (p < 0.001). ROC analysis confirmed the best predictive value for SV (at 56 ml cut-off AUC 0.97, sensitivity 94%, specificity 95%). Slow patterned breathing improved the discriminative value of SVV (p = 0.0023).

Conclusions

Functional hemodynamic monitoring with slow patterned breathing to control spontaneous respiration may be worthy for further study in different populations for the assessment of hypovolemia and the prediction of volume responsiveness.

Time-frequency methods and voluntary ramped-frequency breathing: a powerful combination for exploration of human neurophysiological mechanisms

We experimentally altered the timing of respiratory motoneuron activity as a means to modulate and better understand otherwise hidden human central neural and hemodynamic oscillatory mechanisms. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, tidal carbon dioxide concentrations, and muscle sympathetic nerve activity in 13 healthy supine young men who gradually increased or decreased their breathing frequencies between 0.05 and 0.25 Hz over 9-min periods. We analyzed results with traditional time- and frequency-domain methods, and also with time-frequency methods (wavelet transform, wavelet phase coherence, and directional coupling). We determined statistical significance and identified frequency boundaries by comparing measurements with randomly generated surrogates. Our results support several major conclusions. First, respiration causally modulates both sympathetic (weakly) and vagal motoneuron (strongly) oscillations over a wide frequency range-one that extends well below the frequency of actual breaths. Second, breathing frequency broadly modulates vagal baroreflex gain, with peak gains registered in the low frequency range. Third, breathing frequency does not influence median levels of sympathetic or vagal activity over time. Fourth, phase relations between arterial pressure and sympathetic and vagal motoneurons are unaffected by breathing, and are therefore likely secondary to intrinsic responsiveness of these motoneurons to other synaptic inputs. Finally, breathing frequency does not affect phase coherence between diastolic pressure and muscle sympathetic oscillations, but it augments phase coherence between systolic pressure and R-R interval oscillations over a limited portion of the usual breathing frequency range. These results refine understanding of autonomic oscillatory processes and those physiological mechanisms known as the human respiratory gate.

Biomarkers and endogenous determinants of dofetilide-induced torsades de pointes in α(1) -adrenoceptor-stimulated, anaesthetized rabbits

BACKGROUND AND PURPOSE

Torsades de pointes (TdP) liability is a stochastic event, which indicates that unidentified factors have an important role in facilitating the initiation of TdP by increasing the probability of TdP occurrence. We sought to identify factors that facilitate drug-induced TdP.

EXPERIMENTAL APPROACH

We studied dofetilide-induced TdP in pentobarbital-anaesthetized, phenylephrine-sensitized rabbits, seeking biomarkers that discriminated between the animals that experienced TdP ('TdP+' animals) and those that did not ('TdP-' animals). As novel variables, the beat-to-beat variability and instability of ECG intervals were measured at preset times, irrespective of whether or not hearts were in stable sinus rhythm ('absolute' variability and instability). Autonomic activity was also determined.

KEY RESULTS

Dofetilide delayed repolarization and induced arrhythmias prior to TdP. The variability of the coupling interval and shape of arrhythmic beats before TdP were significantly greater in the 'TdP+' group than in the 'TdP-' group. Accordingly, the 'absolute' variability and instability of the ECG intervals were significantly elevated in the 'TdP+' group. Phenylephrine increased significantly the up-baroreflex sensitivity in the 'TdP+' group before dofetilide administration.

CONCLUSIONS AND IMPLICATIONS

'Preceding' arrhythmias have characteristics that permit prediction of TdP occurrence: the more chaotic the ventricular rhythm, the greater the probability of TdP initiation. This suggests that complexity of the arrhythmic beats may play an important mechanistic role in TdP genesis. The electrical instability quantified by the novel 'absolute' variability and instability parameters correlates with the probability of TdP occurrence. Baroreflex may contribute to TdP genesis in vivo.

[A simple miracle of water]

Chronic orthostasis intolerance or postural tachycardia syndrome (POTS) is a common problem, which is related to the more severe forms of autonomic neuropathy. Upright posture regularly elicits uncomfortable symptoms in these patients, which impairs their quality of life. We present a typical case, where orthostatic hemodynamic response was significantly improved by ingestion of 500 ml tap water. This simple measure could be a potent, long-term therapeutic tool.

Systemic hemodynamics during cough induced and vasovagal syncope

Common faint and the so-called situational syncope are usually listed together in the category of “neurally mediated syncope”. Although vasovagal syncope has been subject of extensive research in the past years, its mechanism is not fully understood. Much less information is available about situational syncope. Numerous entities in this heterogeneous group are related to excessive straining (e.g. weight lifter's or trumpet player's syncope). Cough syncope is also associated with tremendous intrathoracic, intravascular, and even intracranial pressure fluctuations. Although reflex responses are certainly triggered during cough, their relative role, and their analogy with the classical vasovagal reaction are not clear. We report a case of vasovagal syncope and cough reaction occurring in the same subject during laboratory testing.

Spontaneous baroreflex sensitivity and heart rate turbulence parameters: parallel responses to orthostasis

Premature ventricular contractions (PVC-s) induce baroreflex mediated arterial pressure and heart rate fluctuations. PVC-related RR interval fluctuations detected on Holter ECG recordings could be characterized by the heart rate turbulence (HRT) parameters, including early post-extrasystolic acceleration, described by turbulence onset, and late deceleration, described by turbulence slope (TS). We have determined the increasing and decreasing spontaneous baroreflex sequence sensitivity (up- and down-BRS) parameters in supine and in upright position in 12 patients with VVI pacemaker while in sinus rhythm. Five-five premature ventricular pacemaker extrastmuli were also applied in both body positions and HRT parameters were calculated. Up- and down-BRS values showed a very close relationship with TS both in the supine (R = 0.94, P < 0.001 and R = 0.92, P < 0.001, respectively), and upright position (R = 0.96, P < 0.001, and R = 0.94, P < 0.001, respectively). The BRS indices decreased significantly upon tilting, which was paralleled by a significant decrease in TS (from 21.6 to 13.9 ms/cycle, P = 0.02). Our findings confirm the close association between TS and spontaneous BRS indices. The relationship is further supported by the similar postural behavior of these parameters. Our results suggest that the confounding effect of posture should be considered when analyzing Holter recordings.

Coronary artery dissection in the postpartum period – a case study

A spontán coronaria dissectio ritka kórállapot, amely főleg nőkben, gyakran a peripartum időszakában fordul elő. Specifikus kóroki tényező egyértelműen nem azonosítható e nemritkán fatális kimenetelű betegség hátterében. Bemutatjuk egy fiatal, egy hete szült nőbetegünk esetét, aki mellkasi fájdalom miatt került kórházba, és akut ST-elevációs szívinfarktus EKG-jeleit észlelték rajta. A sürgősségi koronarográfia elzáródás nélküli nem szignifikáns szűkületeket észlelt, emiatt intervenció nem történt. Cardiogen sokk alakult ki, amely mechanikus keringéstámogatás segítségével rendeződött, a beteg állapota stabilizálódott, majd ismételt ischaemiás tünetei jelentkeztek, az újabb angiográfia már egyértelmű coronaria dissectio jelenlétét mutatta a bal közös törzs distalis részén, amely már a ramus circumflexus áramlást is limitálta, emiatt urgens coronaria bypass műtét történt jó eredménnyel. A spontán coronaria dissectióra gondolnunk kell a peripartum időszakában kialakult akut coronariaszindrómák esetén, melyek halálozása magas, kezelésében speciális szempontokat kell figyelembe vennünk.

Relevance of anaesthesia for dofetilide-induced torsades de pointes in alpha1-adrenoceptor-stimulated rabbits

BACKGROUND AND PURPOSE

No information is available concerning the effects of anaesthetics in the most frequently used in vivo pro-arrhythmia model. Accordingly, in this study we examined the effect of pentobarbital, propofol or alpha-chloralose anaesthesia on the pro-arrhythmic activity of the class III anti-arrhythmic dofetilide in alpha(1)-adrenoceptor-stimulated rabbits.

EXPERIMENTAL APPROACH

Rabbits anaesthetized intravenously with pentobarbital, propofol or alpha-chloralose were infused simultaneously with the alpha(1)-adrenoceptor agonist phenylephrine (15 microg kg(-1) min(-1), i.v.) and dofetilide (0.04 mg kg(-1) min(-1), i.v.). The electrocardiographic QT interval, the T (peak)-T (end) interval and certain QT variability parameters were measured. The heart rate variability and the baroreflex sensitivity were utilized to assess the vagal nerve activity. The spectral power of the systolic arterial pressure was calculated in the frequency range 0.15-0.5 Hz to assess the sympathetic activity.

KEY RESULTS

Pentobarbital considerably reduced, whereas propofol did not significantly affect the incidence of dofetilide-induced torsades de pointes (TdP) as compared with the results with alpha-chloralose (40% (P=0.011) and 70% (P=0.211) vs 100%, respectively). In additional experiments, neither doubling of the rate of the dofetilide infusion nor tripling of the rate of phenylephrine infusion elevated the incidence of TdP to the level seen with alpha-chloralose. None of the repolarization-related parameters predicted TdP. The indices of the parasympathetic and sympathetic activity were significantly depressed in the alpha-chloralose and propofol anaesthesia groups.

CONCLUSIONS AND IMPLICATIONS

In rabbits, anaesthetics may affect drug-induced TdP genesis differently, which must be considered when results of different studies are compared.

Pseudosyncope and pseudoseizure

A syncope gyakori kórkép, mely jelentős terheket ró az egészségügyre. Bár diagnosztikus eszközeink fejlődnek, az esetek egy kis hányadában az eszméletvesztés pontos oka az alapos kivizsgálás ellenére is rejtve marad. Az ismeretlen eredetű syncopék csoportjába tartozik a pszichogén álsyncope, mely – szemben a valódi syncopéval – nem jár az agyi keringés átmeneti zavarával. Az álsyncope valójában a konverziós betegség egyik megnyilvánulása, és mint ilyen, számos jellegzetességében osztozik az álgörcsrohammal. Az utóbbira ugyancsak jellemző, hogy a rohamok alatt hiányoznak a görcstevékenység jellegzetes neurológiai és EEG-manifesztációi. A két megjelenési forma esetenként ugyanazon betegben váltakozva léphet fel. Közleményünkben egy álsyncopékat és álgörcsrohamokat egyaránt produkáló beteg történetét mutatjuk be. Az eset kapcsán áttekintjük az álsyncope irodalmát, és felhívjuk a figyelmet az interdiszciplináris diagnosztikus megközelítés szerepére.

Respiratory effects on the reproducibility of cardiovascular autonomic parameters

The aim of this study was to assess the influence of breathing pattern on the reproducibility of the most commonly used heart rate and blood pressure variability parameters and baroreflex indices. 5-5 min ECG and blood pressure recordings were made and repeated for 10 healthy volunteers in supine rest on 10 consecutive days during spontaneous and 6 min(-1) patterned breathing. We investigated the following parameters: mean RR interval (RRI); the standard deviation of RR intervals (SDRR); the root mean square of successive differences in RRI (RMSSD); the percentage of RRIs which differed by 50% from the proceeding RRI (PNN50); mean systolic arterial pressure (SAP); the standard deviation of SAP (SAP SD); mean mean arterial pressure (MAP); mean diastolic blood pressure (DAP) and baroreflex indices from spontaneous sequence method (upBRS and downBRS) and from cross spectral analysis (LF alpha, HF alpha). To assess reproducibility for each parameter within- and between-subject variability values were calculated and the ratio of within- and between-subject variability was assessed. In addition, we calculated intraclass correlation coefficient (ICC). Compared to spontaneous respiration during 6 min(-1) patterned breathing the heart rate and blood pressure variability increased; upBRS, LF alpha and HF alpha increased, downBRS did not change. However, ICC showed good reproducibility for most parameters, which did not improve further with controlled breathing. In conclusion, respiration had a strong influence on the most widely used cardiovascular autonomic parameters. The controlling of breathing did not result in consistent improvement in their reproducibility.

Effect of pulseless ventricular tachycardia on sympathetic activity

A szimpatikus aktivitás kamrai ritmuszavarokat serkentő hatása jól ismert. Kevésbé tudott, hogy hemodinamikailag destabilizáló kamrai ritmuszavarok idején a szimpatikus aktivitásfokozódás vérnyomás-stabilizáló (protektív) szerepet játszik. Súlyos balkamra-elégtelenségben szenvedő 62 esztendős betegünk szív-elektrofiziológiai vizsgálata során a szimpatikus izom idegaktivitásának direkt mérésével demonstráltuk az arrhythmiára adott szimpatikus választ. Az eset bemutatásával a ritmuszavarok és az autonóm idegrendszer komplex kapcsolatára hívjuk fel a figyelmet.

The evaluation of gastro-oesophageal reflux and oesophagocardiac reflex in patients with angina-like chest pain following cardiologic investigations

The aims of the study were to assess pathogenetic role of gastro-oesophageal reflux and the oesophago-cardiac reflex in subjects with chest pain. To evaluate the prevalence of gastro-oesophageal reflux disease and the oesophago-cardiac reflex in patients with different coronary artery diseases and in coronary spasm.

PATIENTS, METHODS

Fifty-one patients with chest pain were enrolled after detailed cardiologic evaluation including coronary angiography. The prevalence of gastrooesophageal reflux disease was established by symptom analysis, upper gastrointestinal endoscopy, 24-h oesophageal pH monitoring, and oesophageal manometry. The oesophago-cardiac reflex was established by oesophageal acid perfusion test (0.1 N HCl and 0.9% NaCl, 120-120 ml/10 min in a blinded manner) combined with transoesophageal Doppler echocardiographic coronary flow measurement in the left anterior descending artery.

RESULTS

Gastro-oesophageal reflux disease was established in 45% (23/51) of the patients. Oesophageal acid perfusion decreased the coronary flow velocity in 49% (25/51) of the patients indicating the presence of oesophago-cardiac reflex. Oesophago-cardiac reflex was present more frequently in patients with coronary spasm, than in patients with either epicardial coronary artery disease or microvascular coronary disease (p<0.02). Patients with oesophago-cardiac reflex had higher DeMeester scores, increased number of reflux episodes, fraction time below pH 4, and prolonged acid reflux episodes (p<0.05 for each parameter).

CONCLUSIONS

Gastro-oesophageal reflux disease is frequently established in patients with either epicardial or microvascular coronary artery disease or with coronary spasm. The oesophago-cardiac reflex was more frequently observed in patients with coronary spasm. The combination of oesophageal acid perfusion test and transoesophageal Doppler echocardiographic coronary flow measurement seems to be a useful method for the detection of this reflex. Patients with prolonged gastro-oesophageal acid reflux episodes, erosive oesophagitis and coronary spasm may be at higher risk for the development of linked-angina.

Valsalva maneuver, Müller maneuver: hemodynamic and reflex mechanisms, relevances

A Valsalva- és Müller-manőverek az idő próbáját kiállva, ma is gyakran alkalmazott, egyszerű és népszerű vizsgálóeszközök az orvosi gyakorlatban. A manőverek közönséges élethelyzetek és egyes kórállapotok modellezésére egyaránt alkalmasak. A Valsalva-manővert leginkább neuropathiás betegek autonóm reflex tesztjeként használjuk. Folyamatos noninvazív vérnyomásméréssel kiegészítve, a manőver a hagyományos kardiális, vagális paraméterek mérése mellett a vazomotorválaszok értékelését is lehetővé teszi. A Müller- manővert többnyire obstruktív alvási apnoés (OSA) epizódok szimulálására végeztetjük. A manőver kiegészítése folyamatos vérnyomás-monitorozással és a szimpatikus izom idegaktivitásának (MSNA) mérésével az alvási apnoe szindróma és az ahhoz társuló cardiovascularis betegségek kapcsolatára derít fényt.

Unusual case of orthostatic tachycardia

Bevezetés: Az orthostasis intolerancia, az orthostaticus tachycardia gyakran jelez hypovolemiát, gyógyszermellékhatást vagy autonóm elégtelenséget. Az orthostasisszal provokálható tachyarrhythmia ritka jelenség, emelt fejvégű billenőasztal vizsgálatsorozatokban csak elvétve fordul elő. Célkitűzés: A szerzők egy olyan beteget mutatnak be, akinek AV-csomó reentry tachycardiás paroxysmusait függőleges testhelyzet provokálta. Módszer: Vagusmanőverekkel az anterográd lassú pálya vezetésének blokkolása révén sikeresen szüntették a tachycardiát. Eredmények: Figyelemre méltó, hogy a vagusmanőverek csak vízszintes testhelyzetben bizonyultak hatásosnak. Következtetés: Ez a megfigyelés felhívja a figyelmet a manőverek pontos kivitelezésének fontosságára.

[Haemodynamic instability induced by carotid stent implantation]

Intravascular stent implantation is an attractive therapy for carotid artery stenosis. Severe complications of the interventional procedure however include stroke and death.

AIMS

It has been suggested, that episodes of temporary bradycardia and hypotension upon balloon inflation could be related to adverse outcome.

METHODS

In order to assess the significance of episodic haemodynamic instability 24 consecutive patients were continuously monitored during intravascular intervention. Heart rate and blood pressure variability parameters of the patients, and indices of spontaneous baroreflex sensitivity were determined prior to the procedures. The authors have assessed the potential correlation between the autonomic markers recorded on baseline and the subsequent occurrence of reflex mediated haemodynamic instability.

RESULTS

The authors observations confirmed that bradycardia and hypotension occurs frequently at the time of stent after-dilation. Pauses in excess of 3 seconds occurred in 29% of patients. Atropine was administered at 7 instances. The magnitude of systolic blood pressure drop was greater among patients with pauses, however substantial pressure drop was seen among those without pauses as well. No severe complications were seen. Heart rate variability and spontaneous baroreflex sensitivity were reduced in the whole studied population, allowing no prediction of episodes with bradycardia and hypotension.

CONCLUSION

The authors findings indicate that reflex mediated haemodynamic instability induced by carotid artery intervention is a benign phenomenon. Analysis of autonomic markers is of limited value in this patient population.

[Interhospital transport of acute coronary syndrome patients from Bács-Kiskun county]

INTRODUCTION

As an alternative to thrombolysis, primary percutaneous coronary intervention is increasingly utilized in Hungary for treating acute ST elevation myocardial infarction. Heart catheterization laboratories however are not readily available in vast areas of the country. The benefits of primary intervention may fade away with long distance transportation.

METHODS

In order to assess real life practice, the authors have retrospectively studied the interhospital delays of patients transferred with acute coronary syndromes from Bács-Kiskun county between April 2000 and March 2003. This is the largest county of Hungary, with population of 570,000, with no local hemodynamic laboratory. Patients with acute coronary syndromes are transferred to the Cardiac Centers of the Universities of Szeged and Pécs, as well as to 3 designated hospitals with heart catheterization facilities at Budapest. Interhospital delay was defined as the time elapsed from the call of the Emergency Medical Service to the admission of the patient to the catheterization laboratory.

RESULTS

During the studied period 94 patients were transported with acute coronary syndrome. In 79 cases the complete medical documentation from the primary hospitals and the hemodynamic laboratories could be collected. 17 patients with ST-elevation were transported for primary intervention. Twenty-six patient received both thrombolytic and interventional therapy. Further 36 patients suffered from non ST elevation myocardial infarction or unstable angina. Interhospital delay for the whole group was 166 +/- 55 minutes, and for the subgroup of ST-elevation patients awaiting for primary intervention 148 +/- 43 minutes. The transfer time, i.e. the time that the patient spent on the road or in the air lasted longer than 90 minutes in 80% of cases. Air transportation resulted in no reduction of transport time. This finding may be explained by the fact, that both the sending and receiving hospitals lack appropriate helicopter landing sites.

CONCLUSION

The authors conclude, that for those residents of Bács-Kiskun county who suffer from acute ST-elevation myocardial infarction, and have no contraindications for thrombolysis, primary intervention is not a viable therapeutic option.

[Postural tachycardia syndrome]

Erect posture could be a source of diverse chronic symptoms usually referred as orthostasis intolerance. Increasing number of patients suffering from orthostatic syndromes is recognized. Characterization and distinction of these orthostatic syndromes are based on the clinical presentation; including the typical history of orthostasis intolerance, and the unique hemodynamic responses on assuming upright posture. The diagnosis of postural tachycardia syndrome (POTS) requires orthostatic heart rate acceleration in excess of 120 beat/min, or an absolute increase of > or = 30 beat/min, in the absence of significant orthostatic hypotension. Subjects with POTS often exhibit more widespread symptoms of autonomic dysregulation. The diagnosis of inappropriate sinus tachycardia (IST) is based on the presence of resting tachycardia defined by pulse rate of > or = 100 beat/min, or a heart rate acceleration to same range in response to minimal stress, or activity. For the illustration of the difficulties in differentiation between these overlapping syndromes the authors present a case with POTS. The unique features of the presented case are the extreme orthostatic tachycardia (170/min), and the unexpected therapeutic effect of sinus node radiofrequency modification. We suggest a relationship between the peak orthostatic heart rate and the therapeutic value of sinus node modification.

Favorable Early Outcome of Carotid Artery Stenting Without Protection Devices

Background and Purpose— Protection devices are increasingly used in carotid artery stenting. However, no randomized trial has been conducted to evaluate the efficacy of such devices, and arguments have also been formulated against their routine use. We set out to investigate the complication rates associated with carotid artery stenting performed without protection devices. Applicability of covered stents in the carotid system was also evaluated.

Methods— Between January 2001 and July 2003, 245 consecutive patients (260 hemispheres) underwent carotid artery stenting. No protection devices were applied. Covered stents were implanted in 31 (12.1%) cases. The incidence of complications during the intervention and the subsequent 30-day follow-up period was recorded.

Results— The technical success rate was 98.8%. One postprocedural nonneurological death (0.4%) occurred. Neurological complications (inclusive of transient ischemic attacks) were observed in 14 cases (5.4%). The rate of major complications (death, major stroke, and myocardial infarction) was 1.6% among the symptomatic and 1.5% among the asymptomatic cases. The rate of minor strokes was 3.2% in the symptomatic and 1.5% in the asymptomatic group. Of the neurological complications, 64.3% occurred postprocedurally. No ipsilateral neurological complications were detected in the subgroup treated with covered stents.

Conclusions— Carotid artery stenting without protection devices appears to be safe. Most of the neurological complications could not have been prevented with protection devices, because they occurred after the intervention. The application of covered stents may reduce the rate of embolization-related complications in the periprocedural period.

[Mechanism of cough syncope]

Cough induced syncope belongs to the heterogenous group of situational syncopes. The mechanism of tussive syncope is demonstrated by presenting an illustrative case. A 79 year old male with underlying COPD was evaluated because of repeated cough related syncopal episodes. The nature of fainting was elucidated by haemodynamic monitoring of an induced cough attack. As documented by continuous blood pressure and middle cerebral artery blood flow velocity recordings, fainting was the result of the equalization of arterial and central venous pressures, with concomitant decrease in cerebral blood flow. Analogies and differences between haemodynamic responses induced by cough and Valsalva straining are highlighted. The typical lack of prodromal symptoms in cough syncope are well explained by the rapidly developing cerebral hypoperfusion.

Oesophageal acid stimulation in humans: does it alter baroreflex function?

The aim of this study was to investigate if oesophagel acid stimulation (Bernstein test) had an influence on heart rate and blood prsure variability and baroreflex gain. We compared the cardiovascular responses in 10 patients with established gastro-esophageal reflux disease (Group 1) and 10 control subjects (Group 2) during esophageal saline and 0.1 mol/l hydrochloric acid instillation. Indices of heart rate and blood pressure variability and baroreflex gain (derived from linear spontaneous sequences and cross spectral analysis) were calculated. In Group 1 the standard deviation of RR intervals (SDRR: 46 ms vs 51 ms, p=0.030) and the root mean square of successive differences (RMSSD: 24 ms vs. 26 ms p=0.027) were significantly lower during acid infusions, than during saline. We found no significant difference in minimum, maximum and mean RR intervals and systolic blood pressures and in the percentage of RR intervals, which differed from adjacent cycles by more than 50 ms (PNN50). The power spectra of RR intervals in the high frequency band tended to be lower during acid infusion (p=0.055). There was no significant difference in blood pressure spectra, neither in low nor in high frequency band. In Group 2 there was no significant difference between any parameters measured during acid and saline. The baroreflex gain was not changed during the studied conditions in any group. Neither increased vagal tone, nor increased vagal variability occurred and the baroreflex gain was not altered during oesophageal acid simulation.

Human autonomic responses to blood donation

In order to characterize autonomic responses to acute volume loss, supine ECG, blood pressure (BP) and uncalibrated breathing signal (UBS) recordings were taken before and after blood donation in 48 healthy volunteers. Time and frequency domain parameters of RR interval (RRI), BP and UBS variability were determined. Baroreflex gain was calculated by the technique of the spontaneous sequences and cross-spectral analysis. The systolic (SAP), diastolic (DAP) and mean BP (MAP) increased after the blood withdrawal. The central frequency of breathing and mean heart rate did not change. RRI variability increased in low frequency band (LF), tended to decrease in high frequency band (HF). Systolic BP variability increased in both frequency bands, but was statistically significant only in the high frequency band. Diastolic BP power increased in both frequencies. From the different baroreflex gain estimates, up sequence BRS and HF alpha index decreased significantly. The phase angle between RRI and systolic blood pressure powers in LF band did not change (-58 +/- 24 degrees and -54 +/- 26 degrees ). In the high frequency range, the phase became more negative (-1 +/- 29 degrees and -17 +/- 32 degrees, p = 0.001). The withdrawal of 350-400 ml blood in 5 min resulted in sympathetic activation, which was reflected in increased systolic, diastolic and mean BP. The increased BP oscillation was a sensitive marker of the minor volume depletion. This was coupled by increased RRI oscillation via baroreflex mechanisms in the LF band. Changes in the RRI and BP oscillations in the HF band showed no similar coupling. That points to the fact that RRI oscillations in this band should not be explained entirely by baroreflex mechanisms. Vagal withdrawal was reflected in decreased root mean square of successive differences (RMSSD), decreased HF RRI power and decreased up sequence BRS.

Cardiovascular autonomic dysfunction in primary Sjögren's syndrome

OBJECTIVE

To assess the occurrence and clinical significance of a cardiovascular autonomic nervous system dysfunction in primary Sjögren's syndrome (pSS).

METHODS

Fifty-one pSS patients participated in this case-control study. Heart rate and blood pressure variability measurements, spontaneous baroreflex sensitivity examinations and cardiovascular reflex tests were performed.

RESULTS

The results of the heart rate and blood pressure variability measurements and also the baroreflex sensitivity parameters of the pSS patients peaked in the lowest percentile ranges of a database on 559 healthy control subjects (P < 0.05). In three of the five cardiovascular reflex tests, the frequencies of abnormal results were significantly higher among the patients than among the controls (P < 0.05), and the median autonomic neuropathy score was also elevated (3 vs 0 in the controls; P < 0.0001).

CONCLUSION

Signs of an autonomic nervous system dysfunction involving the cardiovascular system can be discerned in the majority of pSS patients.

[Malignant vasovagal syncope]

The diagnosis of epilepsy is complicated by various conditions that can mimic an epileptic seizure. Many patients with abnormal seizure activity during loss of consciousness may have cardiovascular syncope with global cerebral hypoxia (convulsive syncope), which may be difficult to differentiate from epilepsy on clinical grounds. The differentiation is, however, important because they need quite different treatment modalities. In addition, long-term anticonvulsant therapy is expensive and can cause serious morbidity. The authors present a case of a patient thought to have treatment-resistant epilepsy for years with recurrent seizure-attacks, who were subsequently found to have a malignant vasovagal reaction of 24s-asystole as a cause for the so called convulsive syncope. A simple, non-invasive evaluation of circulatory responses to acute orthostasis, the head-up tilt table test, can identify cardiovascular reflex abnormalities in patients with recurrent idiopathic seizure-like episodes. The authors could also reproduce the symptoms of the spontaneous attacks in their patient by this way, to confirm an alternative diagnosis of malignant vasovagal reaction and convulsive syncope in this patient with "refractory epilepsy". This rare cardioinhibition can be safely treated by dual-chamber pacemaker implantation, alleviating for the convulsive attacks, this therapeutic option was advised to this patient as well. Orthostatic stress tests should be considered early in the diagnostic workup of patients with convulsive blackouts. Cardiac causes of loss of consciousness should be considered in patients with presumed epilepsy, atypical premonitory symptoms, non-diagnostic electroencephalograms and failure to respond to anticonvulsant therapy.

[Torsades de pointes ventricular tachycardia induced by intravenous amiodarone]

The authors report on the case history of a 61 year old woman with hyperthyroidism induced atrial fibrillation, tachycardiomyopathy and congestive heart failure, in whom life threatening ventricular proarrhythmia (torsades de pointes) developed in response to intravenous amiodarone. The patient in a septic state was resuscitated because of ventricular fibrillation. The atrial fibrillation complicated by a high ventricular frequency was slowed down with intravenous amiodarone; additionally, the iodine-containing antiarrhythmic drug was expected to counter thyrotoxicosis. In response to amiodarone (2 x 300 mg), the sinus rhythm was restored, but the excessive post-cardioversion bradycardia led to the development of extreme QT interval prolongation and torsades de pointes ventricular tachycardias that often degenerated into ventricular fibrillation. In connection with this case, the authors survey those electropharmacological and pathophysiological factors which may have played a role in the emergence of ventricular proarrhythmia based on a lengthening of repolarization through the exhaustion of the repolarization reserve.

Measures of cardiovascular autonomic regulation derived from spontaneous methods and the Valsalva maneuver

The response of heart rate to a given change of systolic blood pressure is a fundamental characteristic of the cardiovascular system. The assessment of baroreflex gain (BRS) as an index of baroreflex function is based on the quantification of RR interval changes related to blood pressure changes. The spontaneous sequence and cross spectral methods describe baroreflex gain derived from spontaneous fluctuations of these parameters, yielding the up sequence and down sequence BRS and the alfa index. Phase IV of the Valsalva maneuver is also used to calculate cardiac vagal baroreflex gain. In this study, we compared the two spontaneous methods and the Valsalva maneuver in assessing baroreflex gain in 56 healthy volunteers. The BRS values calculated from different methods were as follows: up sequence BRS 12 +/- 8.6 ms/mm Hg, down sequence BRS 10 +/- 6.1 ms/mm Hg, low frequency alfa index 12.1 +/- 8.2 ms/mm Hg, Valsalva BRS 9.7 +/- 7.2 ms/mm Hg. We found close relationship between baroreflex gain derived from up and down sequences (R = 0.91, p < 0.001), down sequence BRS and low frequency alfa index (R = 0.81, p < 0.001); significant correlation between up sequence BRS and low frequency alfa index (R = 0.65, p < 0.001), the Valsalva-derived BRS and down sequence BRS (R = 0.37, p = 0.043), but no correlation between the Valsalva BRS and up sequence BRS, the Valsalva BRS and low frequency alfa index. BRS values calculated by different methods decreased with increasing age. There was no influence of age on mean arterial blood pressure elevation in late phase II of the Valsalva maneuver, nor any indication that the Valsalva BRS was related to the MAP changes. We concluded that all of these methods are useful in calculating baroreflex gain, but owing to the differences in underlying physiological mechanisms, they are not necessarily in correlation with each other.

[Wenckebach AV block, as part of vasovagal syncope]

Vasovagal syncope or common faint is the most frequent form of syncopes. With regard to the different involvement of the efferent mechanisms, several forms of the neurally mediated syncope syndromes are recognized. The authors present a case of mixed type vasovagal syncope, diagnosed by tilt table testing. The efferent mechanisms of syncope included Wenckebach type atrioventricular block due to increased vagal tone, and sympathetic withdrawal, reflected by sudden drop in the blood pressure. The significance and interrelationship of these factors are discussed.