Cardiac resynchronization therapy (CRT) has proven efficacious in reducing or even eliminating cardiac dyssynchrony and thus improving heart failure symptoms. However, quantification of mechanical dyssynchrony is still difficult and identification of CRT candidates is currently based just on the morphology and width of the QRS complex. As standard 12-lead ECG brings only limited information about the pattern of ventricular activation, we aimed to study changes produced by different pacing modes on the body surface potential maps (BSPM). Total of 12 CRT recipients with symptomatic heart failure (NYHA II-IV), sinus rhythm and QRS width ≥120 ms and 12 healthy controls were studied. Mapping system Biosemi (123 unipolar electrodes) was used for BSPM acquisition. Maximum QRS duration, longest and shortest activation times (ATmax and ATmin) and dispersion of QT interval (QTd) were measured and/or calculated during spontaneous rhythm, single-site right- and left-ventricular pacing and biventricular pacing with ECHO-optimized AV delay. Moreover we studied the impact of CRT on the locations of the early and late activated regions of the heart. The average values during the spontaneous rhythm in the group of patients with dyssynchrony (QRS 140.5±10.6 ms, ATmax 128.1±10.1 ms, ATmin 31.8±6.7 ms and QTd 104.3±24.7 ms) significantly
differed from those measured in the control group (QRS 93.0±10.0 ms, ATmax 79.1±3.2 ms, ATmin 24.4±1.6 ms and QTd 43.6±10.7 ms). Right ventricular pacing (RVP) improved significantly only ATmax [111.2±10.6 ms (p<0.05)] but no other measured parameters. Left ventricular pacing (LVP) succeeded in improvement of all parameters [QRS 105.1±8.0 ms (p<0.01), ATmax 103.7±7.1 ms (p<0.01), ATmin 20.2±3.7 ms (p<0.01) and QTd 52.0±9.4 ms (p<0.01)]. Biventricular pacing (BVP) showed also a beneficial effect in all parameters [QRS 121.3±8.9 ms (p<0.05), ATmax 114.3±8.2 ms (p<0.05), ATmin 22.0±4.1 ms (p<0.01) and QTd 49.8±10.0 ms (p<0.01)]. Our results proved beneficial outcome of LVP and BVP in evaluated parameters (what seems to be important particularly in the case of activation times) and revealed a complete return of activation
times to normal distribution when using these CRT modalities.
The aims were to explore the effect of head-up tilt (HUT) to 30 and 60 degrees on hemodynamics and tissue oxygenation in anesthetized healthy swine. The data serve as a reference for a study of resuscitation efficacy at HUT such as during transport. Nine healthy swine (49±4 kg) were anesthetized and multiple sensors including myocardial pressure-volume loops catheter, carotid flow probe, blood pressure catheters, near infrared spectroscopy (NIRS) tissue oximetry and mixed venous oximetry (SVO2) catheter were introduced and parameters continuously recorded. Experimental protocol consisted of baseline in supine position (15 min), 30 degrees HUT (15 min), recovery at supine position (15 min) and 60 degrees HUT (5 min). Vacuum mattress was used for body fixation during tilts. We found that 30 and 60 degrees inclination led to significant immediate reduction in hemodynamic and oximetry parameters. Mean arterial pressure (mm Hg) decreased from 98 at baseline to 53 and 39, respectively. Carotid blood flow dropped to 47 % and 22 % of baseline values, end diastolic volume to 49 % and 53 % and stroke volume to 47 % and 45 % of baseline. SVO2 and tissue oximetry decreased by 17 and 21 percentage points. The values are means. In conclusions, within minutes, both 30 and 60 degrees head-up tilting is poorly tolerated in anesthetized swine. Significant differences among individual animals exist., M. Mlcek, J. Belohlavek, M. Huptych, T. Boucek, T. Belza, S. Lacko, P. Krupickova, M. Hrachovina, M. Popkova, P. Neuzil, O. Kittnar., and Obsahuje bibliografii
Extracorporeal membranous oxygenation (ECMO) is increasingly used in the management of refractory cardiac arrest. Our aim was to investigate early effects of ECMO after prolonged cardiac arrest. In fully anesthetized swine (48 kg, N=18) ventricular fibrillation (VF) was induced and untreated period (20 min) of cardiac arrest commenced, followed by 60 min extracorporeal reperfusion (ECMO flow 100 ml/kg.min). Hemodynamics, arterial blood gasses, plasma potassium, tissue oximetry (StO2) and cardiac (EGM) and cerebral (BIS) electrophysiological parameters were continuously recorded and analyzed. Within 3 minutes of VF hemodynamic and oximetry parameters fall abruptly while metabolic parameters destabilize gradually over 20 minutes peaking at pH 7.04±0.05, pCO2 89±14 mmHg, K+ 8.5±1.6 mmol/l. During reperfusion most parameters restore rapidly: within 3-5 minutes mean arterial pressure reaches >40 mmHg, StO2 >50 %, paO2 >100 mmHg, pCO2 <50 mmHg, K+ <5 mmol/l. EGMs mean amplitude peaks at 4.5±2.4 min. Cerebral activity (BIS>60) reappeared in 5 animals after 87±21 min. In 12/18 animals return of spontaneous circulation was achieved. In conclusions, ECMO provides rapid restitution of internal milieu even after prolonged arrest. However, despite normalization of global parameters full recovery was not guaranteed since cardiac and cerebral electrical activities were sufficiently restored only in some animals. More sensitive and organ specific indicators need to be identified in order to estimate adequacy of cardiac support devices., M. Mlček, ... [et al.]., and Obsahuje seznam literatury
Cardiac resynchronization therapy (CRT) has proven efficacious
in the treatment of patients with heart failure and
dyssynchronous activation. Currently, we select suitable CRT
candidates based on the QRS complex duration (QRSd) and
morphology with left bundle branch block being the optimal
substrate for resynchronization. To improve CRT response rates,
recommendations emphasize attention to electrical parameters
both before implant and after it. Therefore, we decided to study
activation times before and after CRT on the body surface
potential maps (BSPM) and to compare thus obtained results with
data from electroanatomical mapping using the CARTO system.
Total of 21 CRT recipients with symptomatic heart failure (NYHA
II-IV), sinus rhythm, and QRSd ≥150 ms and 7 healthy controls
were studied. The maximum QRSd and the longest and shortest
activation times (ATmax and ATmin) were set in the BSPM maps
and their locations on the chest were compared with CARTO
derived time interval and site of the latest (LATmax) and earliest
(LATmin) ventricular activation. In CRT patients, all these
parameters were measured during both spontaneous rhythm and
biventricular pacing (BVP) and compared with the findings during
the spontaneous sinus rhythm in the healthy controls. QRSd was
169.7±12.1 ms during spontaneous rhythm in the CRT group and
104.3±10.2 ms after CRT (p<0.01). In the control group the
QRSd was significantly shorter: 95.1±5.6 ms (p<0.01). There
was a good correlation between LATmin(CARTO) and
ATmin(BSPM). Both LATmin and ATmin were shorter in the
control group (LATmin(CARTO) 24.8±7.1 ms and ATmin(BSPM)
29.6±11.3 ms, NS) than in CRT group (LATmin(CARTO) was
48.1±6.8 ms and ATmin(BSPM) 51.6±10.1 ms, NS). BVP
produced shortening compared to the spontaneous rhythm of
CRT recipients (LATmin(CARTO) 31.6±5.3 ms and ATmin(BSPM)
35.2±12.6 ms; p<0.01 spontaneous rhythm versus BVP). ATmax
exhibited greater differences between both methods with higher
values in BSPM: in the control group LATmax(CARTO) was
72.0±4.1 ms and ATmax (BSPM) 92.5±9.4 ms (p<0.01), in the
CRT candidates LATmax(CARTO) reached only 106.1±6.8 ms
whereas ATmax(BSPM) 146.0±12.1 ms (p<0.05), and BVP paced
rhythm in CRT group produced improvement with
LATmax(CARTO) 92.2±7.1 ms and ATmax(BSPM) 130.9±11.0 ms
(p<0.01 before and during BVP). With regard to the propagation
of ATmin and ATmax on the body surface, earliest activation
projected most often frontally in all 3 groups, whereas projection
of ATmax on the body surface was more variable. Our results
suggest that compared to invasive electroanatomical mapping
BSPM reflects well time of the earliest activation, however
provides longer time-intervals for sites of late activation.
Projection of both early and late activated regions of the heart on
the body surface is more variable than expected, very likely due
to changed LV geometry and interposed tissues between the
heart and superficial ECG electrode.
Early recognition of collapsing hemodynamics in pulmonary embolism is necessary to avoid cardiac arrest using aggressive medical therapy or mechanical cardiac support. The aim of the study was to identify the maximal acute hemodynamic compensatory steady state. Overall, 40 dynamic obstructions of pulmonary artery were performe d and hemodynamic data were collected. Occlusion of only left or right pulmonary artery did not lead to the hemodynamic collapse. When gradually obstructing the bifurcation, the right ventri cle end-diastolic area expanded proportionally to pulmonary artery mean pressure from 11.6 (10.1, 14.1) to 17.8 (16.1, 18.8) cm 2 (p<0.0001) and pulmonary artery mean pressure increased from 22 (20, 24) to 44 (41, 47) mmHg (p<0.0001) at the poin t of maximal hemodynamic compensatory steady state. Sim ilarly, mean arte rial pressure decreased from 96 (87, 101) to 60 (53, 78) mmHg (p<0.0001), central venous pressure increased from 4 (4, 5) to 7 (6, 8) mmHg (p<0.0001), heart rate increased from 92 (88, 97) to 147 (122, 165) /min (p<0.0001), contin uous cardiac output dropped from 5.2 (4.7, 5.8) to 4.3 (3.7, 5.0) l/min (p=0.0023), modified shock index increased from 0.99 (0.81, 1.10) to 2.31 (1.99, 2.72), p<0.0001. In conclusion, in stead of continuous cardiac output all of the analyzed parameters can sensitively determine the individual maximal compensatory response to obstructive shock. We assume their monitoring can be used to predict the critical phase of the hemodynamic status in routine practice., J. Kudlička ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The growth in the experimental research of facilities to support extracorporeal circulation requires the further development of models of acute heart failure that can be well controlled and reproduced. Two types of acute heart failure were examined in domestic pigs (Sus scrofa domestica ): a hypoxic model (n=5) with continuous perfusion of the left coronary artery by hypoxic deoxygenated blood and ischemic model (n=9) with proximal closure of the left coronary artery and controlled hypoperfusion behind the closure. The aim was a severe, stable heart pump failure defined by hemodynamic parameters changes: a) decrease in cardiac output by at least 50 %; b) decrease in mixed venous blood saturation to under 60 %; c) left ventricular ejection fraction below 25 %; and d) decrease in flow via the carotid arteries at least 50 %. Acute heart failure developed in the first group in one animal with no acute mortality and in the second group in 8 animals with no acute mortality. In the case of ischemic model the cardiac output fell from 6.70±0.89 l/min to 2.89±0.75 l/min. The saturation of the mixed venous blood decreased from 83±2 % to 58±8 %. The left ventricular ejection fraction decreased from 50±8 % to 19±2 %. The flow via the carotid arteries decreased from 337±78 ml/min to 136±59 ml/min (P≤0.001 for all comparisons). The proposed ischemic model is not burdened with acute mortality in the development of heart failure and is suitable for further use in experimental research into extracorporeal circulatory support., S. Lacko, M. Mlček, P. Hála, M. Popková, D. Janák, M. Hrachovina, J. Kudlička, V. Hrachovina, P. Ošťádal, O. Kittnar., and Obsahuje bibliografii