BACKGROUND: Has been reported that patients exhibiting prolonged paced QRS duration tend to have more serious heart disease, and the paced QRS duration can be an effective indicator of impaired left ventricular function. However, the acute and chronic hemodynamic effects of paced QRS duration and pacing sites during right ventricular (RV) pacing remain unknown. METHODS: A total of 14 patients who underwent electrophysiologic study for paroxysmal supraventricular tachycardia were examined. RV pacing was performed at 10 different sites with cycle lengths of 600 ms and 500 ms utilizing a 6-7F deflectable quadripolar electrode catheter. Systolic, diastolic, and mean blood pressures during pacing were measured once the blood pressure was stabilized. RESULTS: During RV pacing, blood pressures (systolic/diastolic/mean) decreased. The change of post-pacing QRS duration and pre-pacing the systolic blood pressure (SBP) were greater in the group with paced QRS duration. The differences overall were greater than 140 ms. The SBP decrease during pacing was larger in the group exhibiting paced QRS duration of greater than 140 ms. The SBP decrease during pacing showed relation to QRS duration during pacing (r=0.500, p=0.001), the change of QRS duration post-pacing (r=0.426, p=0.001), and SBP during sinus rhythm (r=0.342, p=0.001) on linear correlation analysis. The pacing site, on the other hand, did not affect acute hemodynamic changes during pacing. CONCLUSION: Ventricular pacing of less than 40 ms at the area of paced QRS duration is recommended.
Blood Pressure/physiology ; *Cardiac Pacing, Artificial ; Electrophysiologic Techniques, Cardiac ; Female ; Heart Ventricles/*physiopathology ; Hemodynamic Processes/*physiology ; Humans ; Male ; Middle Aged ; Tachycardia, Supraventricular/physiopathology/*therapy

We conducted a randomized animal study to determine whether there is a cumulative effect on hemodynamics, pulmonary function, and gas exchange when low dose nitric oxide (NO) is added to partial liquid ventilation (PLV) in acute lung injury. ighteen newborn piglets were saline-lavaged repeatedly, and randomly divided into two groups: PLV with perfluorocarbon group (n=8) and lavage only (control) group (n=10). Perfluorodecalin (30 mL/kg) was instilled into the endotracheal tube for 30 min, followed by 5-10 mL/kg/hr. Fifteen minutes after the completion of perfluorodecalin dosing, NO (10 ppm) was added to the inspiratory gas in an "on/off" manner. Perfluorodecalin instillation produced a significant improvement in gas exchange, pulmonary mechanics, shunt, and pulmonary arterial pressure (PAP). The addition of NO produced a further significant improvement in PaO2 and PAP. The "on/off" response to NO was seen apparently in PAP, PaO2, dynamic compliance, and shunt. All the variables in control group were remained at near the after-lavage levels without significant improvements until the end of the experiment. We concluded that NO might have a cumulative effect on gas exchange when combined with PLV, and this might be attributable to deceased PAP and V/Q mismatching.
Administration, Inhalation ; Animals ; Animals, Newborn ; Fluorocarbons/metabolism ; Hemodynamic Processes ; *Liquid Ventilation ; Nitric Oxide/administration & dosage/*metabolism ; Plasma Substitutes/metabolism ; Pulmonary Gas Exchange/*physiology ; Random Allocation ; *Respiratory Distress Syndrome, Adult ; Respiratory Mechanics ; *Respiratory Physiology ; Support, Non-U.S. Gov't ; Swine

This study was designed to obtain new parameters representing left ventricular (LV) function independent of irregular RR intervals in atrial fibrillation (AF). AF patients were divided into Normal (n=9) and LV Dysfunction (n=9) groups. The relations between LV outflow peak ejection velocity (Vpe) and preceding (RR-1) or prepreceding RR intervals (RR-2) were obtained using logarithmic equations, from which the squared correlation coefficient (r2), slope, Vpe at RR-1 or RR-2=1 sec (Vpe-1), and the ratio of slope to Vpe-1 (Slope/Vpe-1) were calculated. Among the parameters between RR-1 and Vpe, Slope/Vpe-1 was higher in LV Dysfunction group than in Normal group (p=0.05). When only coordinates with RR-1 from 0.6 to 1 sec were included, Slope/Vpe-1 (p=0.001) was higher in LV Dysfunction group than in Normal group. Among the parameters between RR-2 and Vpe, Slope/Vpe-1, slope, and r2 were different between the two groups. In multivariate analysis, Slope/Vpe-1 between RR-2 and Vpe was only independent parameter. However, Slope/Vpe-1 between RR-1 and Vpe in the coordinates with RR-1 from 0.6 to 1 sec had the highest discriminating power. New parameters derived from the relations between RR intervals and LV performance might be useful to evaluate LV function quantitatively in AF.
Age Factors ; Aged ; Atrial Fibrillation/*metabolism ; Atrial Function, Left ; Echocardiography ; Echocardiography, Doppler, Pulsed ; Electrocardiography ; Female ; Heart/physiology ; Heart Ventricles ; Hemodynamic Processes ; Humans ; Male ; Middle Aged ; Models, Theoretical ; Multivariate Analysis ; Myocardial Contraction ; Myocardium/pathology ; Time Factors ; *Ventricular Function, Left

In the present study, we tested whether maintenance of adequate cerebral perfusion pressure (CPP) by pharmacologically preventing systemic hypotension with dopamine infusion would prevent cerebral ischemia and attenuate energy depletion and neuronal injury even though intracranial pressure remains elevated in a newborn piglet meningitis model. Cerebral blood flow, measured at the end of the experiment using fluorescent microspheres, was significantly increased by dopamine infusion. The decreased cerebral cortical cell membrane Na+, K+-ATPase activity and increased lipid peroxidation products, indicative of meningitis-induced brain damage, were significantly attenuated by dopamine infusion. Dopamine also significantly attenuated the meningitis-induced reduction in both brain ATP and phosphocreatine levels and the increase in brain lactate level. In summary, maintenance of adequate CPP with dopamine prevented cerebral ischemia, reduced cerebral energy depletion, and attenuated brain injury in neonatal bacterial meningitis.
Animals ; Animals, Newborn ; Brain/cytology/drug effects/*physiology ; Cell Membrane/*metabolism ; Cerebrovascular Circulation/*drug effects ; Dopamine/metabolism/*pharmacology ; Fluorescent Dyes/metabolism ; Hemodynamic Processes ; Meningitis, Escherichia coli/*metabolism ; Microspheres ; Random Allocation ; Regional Blood Flow ; Support, Non-U.S. Gov't ; Swine

The purpose of the present study was to assess the correlation that likely exists among increased portal pressure (Pp), portal blood flow quantity (Qp) and ETA and ETB receptor mRNA expression in human cirrhosis. In situ hybridization and reverse-transcription polymerase chain reactions (RT-PCR) were performed to determined the expression of ETA and ETB receptor mRNA in liver tissues from traumatic subjects (n = 10) and cirrhotic patients (n = 15) in whom hepatic hemodynamic values were measured. The expression of the two transcripts was significantly higher in liver samples of cirrhotic patients than in those obtained from traumatic subjects. It has shown that ETA receptor mRNA predominantly located in hepatic stellate cells (HSCs) and vascular smooth muscle cells of intrahepatic arteries and portal veins, ETB receptor mRNA in HSCs, sinusoidal endothelial cells and Kuppfer cells. There was a highly significant direct relationship between ETA and ETB receptor mRNA and Pp and Qp in cirrhotic patients. It suggests that liver paracrine endothelin system may be overactivated in human cirrhosis accompanied with increased expression of ETA and ETB receptor mRNA which may play an important role in the pathogenesis and maintenance of splanchnic hyperdynamics.
Gene Expression ; Hemodynamic Processes ; Hypertension, Portal/metabolism ; Liver Cirrhosis/genetics ; Liver Cirrhosis/*metabolism ; Portal Vein/*physiopathology ; Receptors, Endothelin/genetics ; Receptors, Endothelin/*metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; *Splanchnic Circulation/physiology