a1_Fifty years ago, Lewis K. Dahl has presented a new model of salt hypertension – salt-sensitive and salt-resistant Dahl rats. Twenty years later, John P. Rapp has published the first and so far the only comprehensive review on this rat model covering numerous aspects of pathophysiology and genetics of salt hypertension. When we summarized 25 years of our own research on Dahl/Rapp rats, we have realized the need to outline principal abnormalities of this model, to show their interactions at different levels of the organism and to highlight the ontogenetic aspects of salt hypertension development. Our attention was focused on some cellular aspects (cell membrane function, ion transport, cell calcium handling), intra- and extrarenal factors affecting renal function and/or renal injury, local and systemic effects of reninangiotensin-aldosterone system, endothelial and smooth muscle changes responsible for abnormal vascular contraction or relaxation, altered balance between various vasoconstrictor and vasodilator systems in blood pressure maintenance as well as on the central nervous and peripheral mechanisms involved in the regulation of circulatory homeostasis. We also searched for the age-dependent impact of environmental and pharmacological interventions, which modify the development of high blood pressure and/or organ damage, if they influence the saltsensitive organism in particular critical periods of development (developmental windows). Thus, severe self-sustaining salt hypertension in young Dahl rats is characterized by pronounced dysbalance between augmented sympathetic hyperactivity and relative nitric oxide deficiency, attenuated baroreflex as well as by a major increase of residual blood pressure indicating profound remodeling of resistance vessels. Salt hypertension development in young but not in adult Dahl rats can be attenuated by preventive increase of potassium or calcium intake., a2_On the contrary, moderate salt hypertension in adult Dahl rats is attenuated by superoxide scavenging or endothelin-A receptor blockade which do not affect salt hypertension development in young animals., J. Zicha, ... [et al.]., and Obsahuje seznam literatury
Cardiac resynchronization therapy is not commonly used in the early postoperative period in pati ents undergoing cardiac surgery who have left ventricular (LV) dysfunction and a history of heart failure. We performed a prospective randomized clinical trial to compare atrial synchronous right ventricular (DDD RV) and biventricular (DDD BIV) pacing within 72 hours after cardiac surgery in patients with an EF ≤ 35 %, a QRS interval longer than 120 msec and who had LV dyssynchrony detected by real-time three-dimensional echocardiography (RT3DE). Epicardial pacing was provided by a modified Medtronic INSYNC III pacemaker. An LV epicardial pacing lead was implanted on the latest activated segment of the LV based on RT3DE. The study included 18 patients with ischemic heart diseas e, with or without valvular heart disease (14 men, 4 women, average age 71 years). Patients undergoing DDD BIV pacing had a statistically significant greater CO and CI (CO 6.7±1.8 l/min, CI 3.4±0.7 l/min/m²) than patients undergoing DDD RV pacing (CO 5.5±1.4 l/min, CI 2.8±0.7 l/min/m²), p<0.001. DDD BIV paci ng in the early postoperative period after cardiac surgery corrects LV dyssynchrony and has better hemodynamic results than DDD RV pacing., F. Straka ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
This study investigated whether each part of the heart is evenly innervated by the left or right vagus and observed the mechanism of compensatory recovery after unilateral cervical vagotomy. HR, BP, LVSP and ±dp/dt max all decreased one week after left vagotomy, whereas only BP and -dp/dt max decreased one week after right vagotomy. We stern blot analyses revealed that the expression of M2 receptors in the left atrium and left ventricle was upregulated after subacute (1 week) left/right vagotomy. However, significantly more cholinesterase-positive nerves in LV and RV were seen one week after unilateral vagotomy compared to the sham-operated group. In addition, baroreflex sensitivity was increased after subacute right vagotomy. The decreasing effects of ACh (0.5 μ g/kg) on LVSP and ±dp/dt max (but not on HR and BP) were facilitated by subacute unilateral vagotomy. Our present experiments indicate that 1) the working myocardium is innervated bilaterally by the vagus, 2) ventricular contractility is influenced more by denervation of the left than the right vagus and 3) up-regulation of M2 muscarinic receptors in the left heart, increase of cholinergic nerves, and high baroreflex sensitivity could be involved in the mechanism of compensatory hemodynamic recovery via contralateral vagus overactivity, thereby amplifying contralateral vagal activity and decreasing cardiac contractility., L. N. Chen, W. J. Zang, X. J. Yu, J. Liu, D. L. Li, S. S. Kong, J. Lu, X. L. Xu., and Obsahuje bibliografii a bibliografické odkazy
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
Operations in the pleural cavity are connected with circulatory changes in pulmonary circulation and general changes of hemodynamics. These changes are influenced by the position of patient’s body on the operation table and by the introduction of artificial pneumothorax. Thoracoscopy is an advanced surgical approach in thoracic surgery, but its hemodynamic effect is still not known. The aim of the present study was to compare the hemodynamic response to surgeries carried out by open (thoracotomy - TT) and closed (thoracoscopy - TS) surgical approach. Thirty-eight patients have been monitored throughout the operation - from the introduction of anesthesia to completing the surgery. Monitored parameters were systolic blood pressure (BPs), diastolic blood pressure (BPd), O2 saturation (SaO2), systolic blood pressure in pulmonary artery (BPPAs), diastolic blood pressure in pulmonary artery (BPPAd), wedge pressure (PW), central venous pressure in right atrium (CVP), cardiac output (CO) and total peripheral resistance (TPR). No significant difference has been found in hemodynamic response between TT and TS groups. Significant changes of hemodynamic parameters occurring during the whole surgical procedure were detected in both technical approaches. The most prominent changes were found after the position of patients was changed to the hip position (significantly decreased BPs, BPd, MAP, SaO2 and BPPAs) and 5 min after the pneumothorax was established (restoration of the cardiac output to the initial value and significant decrease of the TPR). It can be concluded that the thoracoscopy causes almost identical hemodynamic changes like the thoracotomy., S. Trča ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
In experimental and human diabetes mellitus, evidence for an impaired function of the vascular endothelium has been found and has been suggested to contribute to the development of vascular complications in this disease. The aim of the study was to evaluate possible regional hemodynamic in vivo differences between healthy and diabetic rats which would involve nitric oxide (NO). Central hemodynamics and regional blood flow (RBF) were studied using radioactive microspheres in early streptozotocin (STZ)-diabetic rats and compared to findings in healthy control animals. This method provides a possibility to study the total blood flow and vascular resistance (VR) in several different organs simultaneously. L-NAME iv induced widespread vasoconstriction to a similar extent in both groups. In the masseter muscle of both groups, acetylcholine 2 μg/kg per min, induced a RBF increase, which was abolished by pretreatment with L-NAME, suggesting NO as a mediator of vasodilation. In the heart muscle of both groups, acetylcholine alone was without effect while the combined infusion of acetylcholine and L-arginine induced an L-NAME-sensitive increase in RBF. The vasodilation induced by high-dose acetylcholine (10 μg/kg per min) in the kidney was more pronounced in the STZ-diabetic rats. The results indicate no reduction in basal vasodilating NO-tone in the circulation of early diabetic rats. The sensitivity to vasodilating effects of acetylcholine at the level of small resistance arterioles vary between tissues but was not impaired in the diabetic rats. In the heart muscle the availability of L-arginine was found to limit the vasodilatory effect of acetylcholine in both healthy and diabetic rats. In conclusion, the results indicate a normal action of NO in the investigated tissues of the early STZ-diabetic rat., E. Granstam, S.-O. Granstam., and Obsahuje bibliografii
Pulmonary hypertension (PH) unresponsive to pharmacological intervention is considered a contraindication for orthotopic heart transplantation (OHTX) due to risk of postoperative right-heart failure. In this prospective study, we describe our experience with a treatment strategy of improving severe PH in heart transplant candidates by means of ventricular assist device (VAD) implantation and subs equent OHTX. In 11 heart transplantation candidates with severe PH unresponsive to pharmacological intervention we implanted VAD with the aim of achieving PH to values acceptable for OHTX. In all patients we observed significant drop in pulmonary pr essures, PVR and TPG (p<0.001 for all) 3 months after VAD implantation to values sufficient to allow OHTX. Seven patients underwent transplantation (mean duration of support 216 days) while none of patients suffered right-side heart failure in postoperative period. Two patients died after transplantation and five patients are living in very good condition with a mean duration of 286 days after OHTX. In our opinion, severe PH is not a contraindication for orthotopic heart transplantation any more., J. Kettner ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
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
We investigated non-invasively cardiac contractility and autonomic nervous activity during presyncopal orthostatic stress induced in healthy humans. A graded orthostatic stress (GOS) paradigm, consisting of head-up tilt (HUT) combined with lower body negative pressure (LBNP) of increasing magnitude, was used to reach a presyncopal end-point in 15 healthy adults. Continuous beat-to-beat hemodynamic and autonomic parameters were recorded. From supine control (C1) to presyncope (PS), total peripheral resistance index (TPRI) decreased from 2300±500 to 1910±320 dyne*s*m²/cm^5 (p=0.004), index of contractility (IC) from 59±14 to 27±6 1000/s (p<0.0001), left ventricular working index (LVWI) from 5.2±1.3 vs. 3.6±0.6 mmHg*L/(min*m²) (p=0.0001) and acceleration index (ACI) from 65±18 vs. 54±15 100/s² (p=0.04). Low frequency variation of diastolic blood pressure (LFnudBP) increased from 51±14 to 67±11 % (p=0.0006) and of systolic blood pressure (LFnusBP) from 50±6 vs. 67±8 % (p<0.0001). High frequency variation of RR-interval (HFms²RRI) decreased from 385±320 to 38±43 ms² (p=0.001). From late GOS (G3) to PS, TPRI decreased from 2540±640 to 1910±320 dyne*s*m²/cm^5 (p=0.003), IC from 35±6 to 27±6 1000/s (p=0.003), LVWI from 4.6±0.9 to 3.6±0.6 mmHg*L/(min/m²) (p=0.003), LFnusBP from 71±8 to 67±8 % (p=0.03), LFmmHg²dBP from 6.6±4.0 to 4.8±2.9 mmHg² (p=0.0001), LFmmHg²sBP from 9.7±7.8 to 7.4±4.8 mmHg² (p=0.01). HFnuRRI increased from 19±8 to 28±13 % (p=0.008). Myocardial contractility indices and parameters of sympathetic activity were reduced in the presyncopal state, while parasympathic activity was increased. This suggests a decrease in cardiac contractility during orthostatically induced presyncope in healthy subjects., E. K. Grasser, N. Goswami, H. Hinghofer-Szalkay., and Obsahuje seznam literatury
In some patients, heart failure (HF) is associated with increased pulmonary vascular resistance (PVR). The magnitude and the reversibility of PVR elevation affect the HF management. Sildenafil has been recently recognized as potent PVR-lowering drug in HF. The aim of the study was to compare hemodynamic effects and pulmonary selectivity of sildenafil to prostaglandin E1(PGE1). Right-heart catheterization was performed in 13 euvolemic advanced HF patien ts with elevated PVR (6.3±2 Wood's units). Hemodynamic parameters were measured at the baseline, during i.v. infusion of PGE1 (alprostadil 200 ng·kg-1·min-1 ) and after 40 mg oral do se of sildenafil. Both drugs similarly reduced systemic vascular resistance (SVR), but sildenafil had higher effect on PVR (-28 % vs. -49 %, p=0.05) and transpulmonary pressu re gradient than PGE1. The PVR/SVR ratio - an index of pulmonary se lectivity, did not change after PGE1(p=0.7) but it decreased by -32 % (p=0.004) after sildenafil. Both drugs similarly reduced pulmonary artery mean and wedge pressures and increa sed cardiac index (+27 % and +28 %). Sildenafil led more often to transplant-acceptable PVR while causing smaller drop of mean systemic pressure than PGE1. In conclusion, vasodilatatory effects of sildenafil in patients with heart failure are more pronounced in pulmonary than in systemic circulation., H. Al-Hiti ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy