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PubMed2001

Impaired autonomic function predicts dizziness at onset of paroxysmal atrial fibrillation.

BACKGROUND: Paroxysmal atrial fibrillation is associated with various symptoms, including dizziness, which presumably reflects hemodynamic deterioration. Given the importance of the autonomic nervous system in mitigating the hemodynamic effect of atrial fibrillation, we hypothesized that autonomic function would be predictive of the severity of dizziness. METHODS: The study group comprised 73 patients with paroxysmal atrial fibrillation (mean age 54.1 years, 51 males). Forty-three (59%) patients had lone atrial fibrillation. Mean ventricular rate during atrial fibrillation was 99+/-16 beats/min. On average, patients had a 3-year history of one paroxysm per week lasting 2 h. Autonomic function was assessed using autonomic function tests, including noninvasive measurement of baroreflex sensitivity. Head up tilting was used to test vasovagal reactivity. Severity of dizziness at onset of atrial fibrillation was quantified by the patients using a five-point scale (1=none; 2=light; 3=mild; 4=moderate; and 5=severe). Multivariate analysis was performed to identify the independent predictors of the severity of dizziness. RESULTS: Mean severity of dizziness was 3.36+/-1.65. Multivariate predictors of moderate-to-severe dizziness as opposed to none-to-mild dizziness were a low 30-15 ratio after standing up and low baroreflex sensitivity. Though syncope was never reported nine patients showed a full vasovagal response during head up tilting. CONCLUSIONS: It is concluded that dizziness in patients with "treated" atrial fibrillation in the setting of none to mild structural heart disease is predicted by impaired autonomic function. Vasovagal reactivity appears not to be involved in this connection.

Adult↗
PubMed1987

Renal response to volume expansion in atrial-appendectomized dogs.

The purpose of this study was to determine whether chronic removal of the atrial appendages alters the renal response to volume expansion (VE) in anesthetized dogs. Chronic bilateral atrial appendectomy (ATX) was performed in 10 animals. Six animals served as sham-operated controls (S). The animals were studied 10-14 days after chronic surgery. The protocol consisted of a 20-min control period followed by isochemic VE (20%) and 120 min of post-VE measurements. The dogs were studied a second time, 2 wk later, after acute bilateral cervical vagotomy. Results from the vagi-intact study showed that VE caused a diuresis, natriuresis, and increase in fractional sodium excretion in ATX that did not differ from the response observed in S. VE also caused equivalent increases in central venous and mean arterial pressures in S and ATX. Atrial appendectomy, however, failed to significantly attenuate the increase in atrial natriuretic factor (ANF) after VE. Plasma ANF increased from 27.2 +/- 4.8 to 47.0 +/- 7.3 pg/ml in ATX and from 27.2 +/- 7.8 to 59.0 +/- 17.9 pg/ml in S. After vagotomy, VE caused transient increases in urine flow and sodium excretion. The changes in central venous and mean arterial pressures were not different from the vagi-intact study and vagotomy did not affect the increase in ANF after VE. Circulating ANF levels increased from 26.4 +/- 5.5 to 75.0 +/- 14.0 pg/ml in ATX and from 28.1 +/- 5.7 to 73.0 +/- 22.6 pg/ml in S. These results demonstrate that, in the dog, bilateral ATX does not alter the renal response to volume expansion or attenuate the increase in ANF. In addition, these results show that vagal pathways are not required for the release of ANF and that vagotomy fails to uncover any effect of atrial appendectomy on renal function.

Animals↗
PubMed2005

Transesophageal echocardiographic evaluation of diastolic function.

Diastolic dysfunction is increasingly recognized as a cause of hemodynamic instability in the perioperative setting. Difficulty weaning from cardiopulmonary bypass and an increased need for inotropic support can occur in the absence of systolic impairment. Diastolic dysfunction can also impede hemodynamic stabilization and weaning progress in the mechanically ventilated critically ill patient. The use of transesophageal echocardiography in the ICU can assist in diagnosing the presence and progression of diastolic impairment, which may help to target therapeutic interventions that lead to positive outcomes. This review summarizes the conventional and new echocardiographic modalities for evaluating diastolic function in the perioperative setting.

Algorithms↗
PubMed2005

Diastolic dysfunction and left atrial volume: a population-based study.

OBJECTIVES: We examined the association between diastolic function and left atrial volume indexed to body surface area (LAVi) in a population-based study. BACKGROUND: Atrial enlargement has been suggested as a marker of the severity and duration of diastolic dysfunction (DD). However, the association between DD and atrial enlargement and their individual prognostic implications in the population is poorly defined. METHODS: A cross-sectional sample of Olmsted County, Minnesota, residents > or =45 years of age (n=2,042) underwent comprehensive Doppler echocardiography and medical record review. RESULTS: The LAVi increased with worsening DD: 23 +/- 6 ml/m2 (normal), 25 +/- 8 ml/m2 (grade I DD), 31 +/- 8 ml/m2 (grade II DD), 48 +/- 12 ml/m2 (grades III to IV DD). In bivariate analyses, age, left ventricular mass index, and DD grade were positively associated, whereas female gender and ejection fraction (EF) were inversely associated with LAVi (p <0.001 for all). When controlling for age, gender, cardiovascular (CV) disease, EF, and left ventricular mass, grade II DD was associated with a 24%, and grade III to IV DD was associated with a 62% larger LA volume (p <0.0001 for both). The area under the receiver-operator characteristic curve for LAVi to detect grade I, grade II, or grade III to IV DD was 0.57, 0.81, and 0.98, respectively. Both DD and LAVi were predictive of all-cause mortality, but when controlling for DD, LAVi was not an independent predictor of mortality. CONCLUSIONS: These data suggest that DD contributes to LA remodeling. Indeed, DD is a stronger predictor of mortality; presumably it better reflects the impact of CV disease within the general population.

Aged↗
PubMedDate not supplied

Atrial natriuretic peptide: could it be a marker for postoperative recurrent effusions after Fontan circulation in complex congenital heart defects?

Fontan operation and its modifications are used for the physiological correction of complex congenital heart malformations with functionally single ventricle. Atrial natriuretic peptide (ANP), a physiological diuretic and vasodilator that--together with the effects of cardiopulmonary bypass--plays an important role in the augmentation of capillary permeability in Fontan patients. The rise in right atrial pressure and wall stress is an important stimulus for the release of ANP. ANP levels were measured before and early after surgery in Fontan group (n = 20) and control group (n = 20, patients with simple cardiac defects) to study its influence on and association with mean right atrial pressure, pulmonary vascular resistance (PVR), systemic vascular resistance, amount of drainage during early and late postoperative period, duration of intensive care unit and hospital stay, and need for colloid supplement. Early postoperative ANP values showed a negative correlation with PVR (r = -0.55) and total drainage (r = -0.88). There was no significant change in ANP during surgery or in the postoperative period in control patients. Reduction of PVR and maintenance of efficient urine output are important in the management of Fontan circulation. We conclude that high levels of ANP measured early after Fontan operation can be used as a marker for the successful establishment of Fontan circulation in patients with complex congenital heart defects.

Adolescent↗
PubMed1991

The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure.

On the basis of the known electrophysiologic mechanisms of atrial fibrillation, multiple surgical procedures were designed and tested in dogs to determine the feasibility of developing a surgical cure for human atrial fibrillation. These experimental studies culminated in a surgical approach that effectively creates an electrical maze in the atrium. The atrial incisions prevent atrial reentry and allow sinus impulses to activate the entire atrial myocardium, thereby preserving atrial transport function postoperatively. Since September 1987, this surgical procedure has been applied in seven patients, five with paroxysmal atrial fibrillation of 2 to 9 years' duration and two with chronic atrial fibrillation of 3 and 10 years' duration. All seven patients have been cured of atrial fibrillation and none is receiving any postoperative antiarrhythmic medications.

Adult↗
PubMedDate not supplied

Capacity of intrinsic cardiac neurons to modify the acutely autotransplanted mammalian heart.

The capacity of the intrinsic cardiac nervous system to modify the acutely autotransplanted heart was investigated in eight anesthetized open-chest canine preparations in which the adrenal glands had been removed from the circulation. Cardiac effects elicited by isoproterenol and nicotine were also examined before and after heart-lung transplantation. Cardiac augmentation induced by isoproterenol was similar before and immediately after cardiopulmonary transplantation, indicating that the surgery did not obtund cardiac myocyte function significantly. The initial bradycardia induced by nicotine was greater before transplantation. The subsequent augmentation in left atrial systolic pressure, as well as right and left ventricular intramyocardial systolic pressures, induced by nicotine were similar before and after transplantation. When nicotine was administered to transplanted preparations after atropine administration, cardiac augmentation was induced. Cardiac augmentation was not induced by nicotine after subsequent beta-adrenergic blockade. These data indicate that nicotine-sensitive adrenergic neurons which accompany the transplanted heart are capable of inducing considerable cardiac augmentation. Power spectral analysis of heart rate and left ventricular chamber rate of pressure rise variability indicated an almost complete lack of power in these indexes after, as opposed to before, transplantation. Together with intrinsic cardiac cholinergic neurons, intrinsic cardiac adrenergic neurons may be responsible for physiologically and pharmacologically induced alterations in cardiac variables that occur in acutely transplanted hearts.

Adrenal Glands↗
PubMed2002

Usefulness of phased-array intracardiac echocardiography for the assessment of left atrial mechanical "stunning" in atrial flutter and comparison with multiplane transesophageal echocardiography(*).

We compared transesophageal and phased-array intracardiac echocardiography (TEE/ICE) for the 2-dimensional and spectral Doppler assessment of left atrial (LA) mechanical function. TEE is commonly used to assess LA body and LA appendage mechanical function in patients who are undergoing radiofrequency ablation of typical atrial flutter. Fifteen patients underwent TEE and ICE imaging before and after ablation of typical atrial flutter. The following parameters were measured: (1) LA appendage emptying velocity and fractional area change, (2) severity of LA spontaneous echo contrast (graded 0 to 4), (3) maximal inflow velocity of the left and right upper pulmonary veins, and (5) maximal mitral valve E- and A-wave inflow velocities in sinus rhythm. Diagnostic quality imaging was achieved in all patients with TEE and ICE. Comparing TEE and ICE, the following absolute values and linear correlation coefficient (R) were obtained: preablation LA appendage emptying velocity: 0.45 +/- 0.21 versus 0.44 +/- 0.21 m/s (r = 0.95, p = <0.001); postablation LA appendage velocity: 0.33 +/- 0.24 versus 0.34 +/- 0.24 m/s (r = 0.97, p <0.001); LA appendage fractional area change: 35.3 +/- 13.7 versus 35.9 +/- 17.1% (r = 0.81, p <0.001); left upper/right upper pulmonary vein inflow velocity: 0.50 +/- 0.17/0.49 +/- 0.18 versus 0.51 +/- 0.17/0.47 +/- 0.20 m/s (r = 0.93/0.90, p <0.001); mitral valve E/A wave: 0.66 +/- 0.14/0.31 +/- 0.14 versus 0.69 +/- 0.17/0.35 +/- 0.23 (r = 0.84/0.97, p <0.002); LA spontaneous echo contrast (pre- and postablation): 1.1 +/- 1.2/1.3 +/- 1.2 versus 1.2 +/- 1.3/1.4 +/- 1.3 (r = 0.92/0.90, p <0.001). No patients were identified with LA appendage thrombus. Thus, TEE and phased-array ICE provided equivalent imaging data with high statistical correlation. ICE may be an imaging alternative to TEE in the evaluation of a "stunned" left atrium.

Adult↗
PubMed1991

(Ca2+ + Mg2+) ATPase activity in kidney basolateral membrane in diabetes: role of atrial natriuretic peptide.

The (Ca2+ + Mg2+) ATPase which serves as a Ca2+ pump in the kidney basolateral membranes is essential to the maintenance of an intracellular Ca2+ concentration optimal for kidney function. Since atrial natriuretic peptide (ANP) is known to participate in the Ca2+ homeostasis mechanism, altered levels of ANP in diabetes may vary the pump activity and consequently the kidney function. In order to examine the modulatory role of ANP on (Ca2+ + Mg2+) ATPase in short- (6 weeks) and long-term (6 months) diabetes, rats were injected with streptozotocin (65 mg/kg body wt, i.v.). At 6 weeks, the plasma ANP was decreased whereas, ANP-receptor binding in the kidney basolateral membrane was increased. In contrast, there was an increased plasma ANP and decreased ANP receptor binding at 6 months. Insulin treatment to diabetic animals normalized these parameters. The (Ca2+ + Mg2+) ATPase activity was unchanged both at 6 weeks and 6 months. Our results demonstrate that the unchanged Ca2+ pump activity in short-term and long-term diabetes serves to maintain the Ca2+ homeostasis in the kidney cells and thus may maintain the hyperfiltration state in diabetes. Unaltered (Ca2+ + Mg2+) ATPase is achieved by the initial up-regulation and subsequent down-regulation of the ANP receptors.

Animals↗
PubMed2006

The expression of atrial natriuretic peptide in the oviduct and its functions in pig spermatozoa.

Locally synthesized atrial natriuretic peptide (ANP) and its receptors have been found in reproductive tissues of various mammals, and play an important role in the acrosome reaction of human sperm. The objective of the present study was to examine the expression of ANP and its receptors in pig spermatozoa and oviduct, and the effect of ANP on pig spermatozoa function. The expression of ANP and its receptors was analyzed by RT-PCR. Only natriuretic peptide receptors-A (NPRA) mRNA was detected in fresh sperm. While the levels of natriuretic peptide receptors-C (NPRC) mRNA were low with no obvious change among different oviductal phases, the levels of ANP mRNA were high in oviduct(OT)1 , OT3 and OT5, but were very low in OT2. On the other hand, the levels of NPRA mRNA were low in OT1 and OT2, increased in OT3 and reached a maximum in OT4 and OT5. Western blot analysis revealed that the level of ANP was high in OT1, decreased in OT2 and OT3, and arrived at the nadir in OT4 and OT5. The effect of ANP on spermatozoa function was studied by the acrosome reaction and IVF. Incubation with ANP for 1 h significantly induced acrosome reaction of preincubated spermatozoa, and maximal response of acrosome reaction (34.1 +/- 2.3%) was achieved at 1 nM ANP treatment. Both C-ANP-(4-23), a selective ligand of NPRC, and caffeine had no effect on the acrosome reaction. The stimulatory effect of ANP on acrosome reaction could be mimicked by the permeable cGMP analog, 8-Br-cGMP. ANP and caffeine had a similar effect on improving the oocytes penetration rate, polyspermy rate and the average number of sperm per penetrated oocyte. Also, ANP treatment had a similar effect on cleavage rate, blastocyst formation rate and the number of cells per blastocyst as that of caffeine treatment. The effects of ANP on the acrosome reaction and the parameters of oocyte penetration could be blocked by cGMP-dependent protein kinase (PKG) inhibitors KT5823 and/or Rp-8-pCPT-cGMPS. These results suggest that the expression of ANP in the oviduct may be involved in the regulation of the acrosome reaction and the fertilising ability of pig spermatozoa, and the PKG pathway possibly participates in the process.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

Effects of preoperative treatment with diltiazem on diastolic ventricular function after coronary artery bypass graft surgery.

OBJECTIVE: To examine whether preoperative treatment with diltiazem could ameliorate left ventricular (LV) diastolic dysfunction in patients after coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, nonrandomized clinical study. SETTING: University hospital. PARTICIPANTS: Thirty-four patients with preserved LV function undergoing elective CABG surgery. INTERVENTIONS: According to medical history, patients were divided into 2 groups: patients not receiving diltiazem (n = 17) and patients treated with once-daily oral diltiazem for at least 2 weeks (n = 17). All patients received preoperative beta-blockers. MEASUREMENTS AND MAIN RESULTS: After induction of anesthesia, after sternal closure, and 4 hours after cardiopulmonary bypass (CPB), mitral and pulmonary venous flow velocities were measured with pulsed Doppler. LV short-axis end-diastolic area by Doppler transesophageal echocardiography (TEE) and hemodynamic variables were obtained simultaneously at comparable pulmonary capillary wedge pressures. Postoperatively, increased peak E and A velocities were observed in patients with diltiazem and controls and returned to baseline 4 hours post-CPB in controls. Changes in these velocities did not result in a decreased E/A ratio. Peak A velocity, E/A ratio, and E wave deceleration time were significantly dependent on heart rate, not peak E velocity. End-diastolic area at comparable pulmonary capillary wedge pressure remained unchanged. In relation to diltiazem, only peak A velocity and time velocity integral of the A wave (TVI-A) at 4 hours post-CPB differed from controls. CONCLUSION: Diastolic function is preserved after CABG surgery and is not altered by diltiazem in patients with preserved LV systolic function. The persistence of increased peak A velocity and TVI-A into the postoperative period suggests improved atrial systolic function with diltiazem.

Administration, Oral↗
PubMed1987

The isopotential body surface atrial maps in healthy children of different age groups.

Isopotential body surface maps during atrial excitation were examined by ten beats addition method of the P waves in 32 healthy children divided into three age groups. The moving pattern of the maxima and the minima, and the distribution of areas of positive and negative potentials in each group were similar to those of adults. Quantitative analysis of the duration and amplitude of the anterior and the left maximum, and the shift time from the former to the latter were done. In children the duration and amplitude of the anterior maximum were always larger than those of the left maximum in contrast to findings in adults where no significant difference was found in their values. The higher amplitude of the anterior maximum was found mainly in the youngest group. These parameters of the P maps were also examined in 12 cases of atrial septal defect (ASD). The amplitude and duration of the anterior maximum were larger than those of healthy children at each age group, although the P wave by the conventional ECG did not reveal signs of right atrial overload. These results suggest that the body surface maps of the P waves are useful diagnostic methods to detect atrial disorders in children.

Aging↗