Serum Catecholamine Levels Research Articles

Conquering Cancer Disparities: New Opportunities for Cancer Epidemiology, Biomarker, and Prevention Research

Cancer disparities represent a significant public health problem in the United States. Inequity in cancer screening, incidence, treatment, prognosis, and mortality is a hallmark of many common cancers ([1][1]). These disparities exist across groups defined by race, ethnicity, gender, age, and

Influence of Menstrual Cycle on QT Interval Dynamics

The aim of this study was to investigate the effects of the menstrual cycle on QT interval dynamics and the autonomic tone in healthy women. Holter ECGs were recorded in 11 healthy women aged 18-32 years during the follicular and luteal phases of their regular menstrual cycle. The interval from QRS onset to the apex (QaT) and to the end of the T-wave (QeT), the interval between the apex and the end of the T-wave (Ta-e), and RR intervals were measured automatically in the course of 24 hours by Holter ECGs. The QeT/RR, QaT/RR, and Ta-e/RR relationships were evaluated in each subject. The autonomic tone was assessed by the serum catecholamine level at rest and heart rate variability was measured by Holter ECGs. (1) The follicular and luteal phases did not differ significantly with respect to the slopes of the QeT/RR, QaT/RR, and Ta-e/RR relationships. However, QeT and QaT intervals were significantly shorter for all RR intervals in the luteal than in the follicular phase (P < 0.0001). (2) The serum progesterone concentration was significantly higher in the luteal than in the follicular phase (P < 0.001). (3) Noradrenaline was significantly higher in the luteal than in the follicular phase (P < 0.05). There was no significant difference in the follicular and luteal phases with respect to heart rate variability measurements. Our results suggest that the menstrual cycle affects the QT intervals. The observed shorter QT interval during the luteal than the follicular phase may be attributable to the increase in serum progesterone and sympathetic tone.

Laparoscopic Approach to Pheochromocytoma: Is a Lower Intraabdominal Pressure Helpful?

Laparoscopic adrenalectomy is gaining popularity because of its well-documented benefits. The aim of our study was to see if a decreased intraoperative intraabdominal pressure during laparoscopic adrenalectomy would affect the hemodynamic variables and the serum levels of catecholamines. We randomly divided 9 patients into 2 groups, maintaining either an intraabdominal pressure of 15 mm Hg (group A) or 8-10 mm Hg (group B). Norepinephrine and epinephrine blood levels were measured preoperatively, during endotracheal intubation, carboperitoneum, surgical manipulation of tumor just before the ligation of the adrenal vein, and tracheal extubation; the hemodynamic variables were recorded. The introduction of carboperitoneum resulted in an increase in heart rate and mean arterial blood pressure (MAP), although it was statistically insignificant. The norepinephrine levels showed a statistically significant increase in group A as compared with group B (P = 0.0002). Surgical manipulation of the tumor resulted in a significant increase in MAP and norepinephrine levels in group A (P = 0.007 and P = 0.0001, respectively). The epinephrine levels did not change as much because the tumor was probably predominantly norepinephrine-secreting. Norepinephrine levels continued to be high even during tracheal extubation in group A patients (P = 0.027). We conclude that a low intraabdominal pressure of 8-10 mm Hg causes less catecholamine release and fewer hemodynamic fluctuations.

The Effects of the Inhalation Method Using Essential Oils on Blood Pressure and Stress Responses of Clients with Essential Hypertension

The purpose of this study was to identify the effects of aromatherapy on blood pressure and stress responses of clients with essential hypertension. There were fifty-two subjects divided into an essential oil group, placebo group, and control group by random assignment. The application of aromatherapy was the inhalation method of blending oils with lavender, ylangylang, and bergamot once daily for 4 weeks. To evaluate the effects of aromatherapy, blood pressure and pulse were measured two times a week and serum cortisol levels, catecholamine levels, subjective stress, and state anxiety were measured before and after treatment in the three groups. Data was analyzed by repeated measures of ANOVA, one-way ANOVA, and chi(2)-test using the SPSS 10.0 program. The blood pressure, pulse, subjective stress, state anxiety, and serum cortisol levels among the three groups were significantly statistically different. The differences of catecholamine among the three groups were not significant statistically. The results suggest that the inhalation method using essential oils can be considered an effective nursing intervention that reduces psychological stress responses and serum cortisol levels, as well as the blood pressure of clients with essential hypertension.

Neurocardiogenic Syncope and Related Disorders of Orthostatic Intolerance

Received September 14, 2004; revision received January 31, 2005; accepted March 9, 2005. “We shall not cease from exploration and the end of all our exploring will be to arrive where we started and know the place for the first time” — —T.S. Eliot, Four Quartets Syncope, defined as transient loss of consciousness and postural tone with spontaneous recovery, has both challenged and perplexed physicians since the dawn of recorded time. The earliest written accounts come from Hippocrates, and the word syncope itself is derived from an old Greek term meaning “to cut short” or “interrupt.” Recurrent episodes of syncope may result from a large number of different disorders, all of which cause a transitory reduction in cerebral blood flow sufficient to disturb the normal functions of the brain. Over the last 2 decades, considerable attention has been given to types of syncope that occur due to a centrally mediated (or “reflex”) fall in systemic blood pressure, a condition that has been referred to as vasovagal (and later neurocardiogenic) syncope. However, research into the nature of this disorder revealed that it is but one aspect of a broad and varied group of disturbances in the normal functioning of the autonomic nervous system (ANS), each of which may result in orthostatic intolerance, hypotension, and ultimately syncope. Continued investigations into the nature of these similar yet different disorders has led to the development of a system of classification that attempts to more accurately reflect our understanding of these conditions and their interrelationships.1 The present system of classification has proven both functional and clinically relevant and includes a group of disorders that most investigators have thought to be principally autonomic in nature. Because both the cardiologist and the cardiac electrophysiologist frequently are expected to both diagnose and treat these conditions, the following …

782 Impact of beta-endorphin, prostaglandin F2alfa and total catecholamine serum levels on haemodynamics in the postresuscitation period after cardiac arrest

782 Impact of beta-endorphin, prostaglandin F2alfa and total catecholamine serum levels on haemodynamics in the postresuscitation period after cardiac arrest

A controlled study of serum catecholamine and cortisol levels in patients with panic disorder

目的 探讨惊恐障碍患者治疗前后血清肾上腺素(E)、去甲肾上腺素(NE)和皮质醇(CS)水平的变化.方法 25例惊恐障碍病人,接受药物治疗合并心理治疗共2个月,在治疗前后取血测定上述生化指标,并且进行症状自评量表(SCL-90)、汉密尔顿焦虑量表(HAMA)的评定.选择25例正常健康人作为对照组,同样检测上述生物学指标.结果患者组治疗前血清NE[(9.43±6.98)pg/ml]和CS[(594.23±295.11)nmol/l]水平均高于对照组[(2.09±1.01) pg/ml、(369.80±101.37)nmol/l](P 0.05).治疗前的SCL-90评分与CS水平呈正相关. 结论惊恐障碍患者存在儿茶酚胺和皮质醇的异常.药物治疗合并心理治疗可以使患者的临床症状缓解以及生物学指标恢复正常。

Changes in lymphocyte subsets after short-term pharmacotherapy in patients with panic disorder

Panic disorder is associated with a high frequency of comorbid immunological diseases, such as allergies and asthma, although the psychoneuroimmunology of panic disorder is relatively unexplored. The objective of this study was to determine whether panic patients have different immunological findings compared with normal healthy subjects and whether changes in immune function are associated with short-term pharmacotherapy. We also examined whether immunological variables were associated with clinical severity and serum catecholamine levels. Patients with panic disorder ( n=26) and healthy control subjects ( n=26) were recruited for this study. All patients were treated with paroxetine for 3 months. We measured the lymphocyte subsets, psychopathological characteristics and serum catecholamine (norepinephrine and epinephrine) levels. Panic patients did not differ initially from control subjects in peripheral lymphocyte phenotypic markers. After drug therapy, however, percentages of circulating CD3 +, CD4 + and CD8 + T lymphocytes were significantly increased, while the percentage of CD19 + B lymphocytes was significantly decreased in the patients. The difference in the percentage of CD8 + T lymphocytes before and after treatment was negatively correlated with pretreatment Global Clinical Impression scores. The lymphocyte subsets were not significantly associated with serum catecholamine levels in panic patients. In conclusion, panic patients showed increased CD3 +, CD4 + and CD8 + T lymphocyte proportions and a decreased B lymphocyte proportion after 3 months of drug therapy. This finding suggests that pharmacological treatment may affect immune function in panic patients.

Lipid profile in spinal cord-injured women with different injury levels

Background. In dependence on their injury level, male subjects with spinal cord injury (SCI) exhibit a less favorable lipoprotein profile than control persons. The impairment of the sympathetic nervous system and the fact that persons with spinal cord injury are subject to extreme physical inactivity may have an influence on their lipid profile and lipoprotein(a) concentration. It has been shown that sex-specific differences in hormonal regulation are responsible for differences in lipoprotein levels between nondisabled men and women. However, the role of hormones on lipoprotein levels has not been investigated in female subjects with spinal cord injury. Methods. Therefore, we performed a detailed investigation regarding the lipid profile in 32 premenopausal women with spinal cord injury ranging from tetraplegia to low paraplegia and in 36 control subjects. VO 2max was determined by a wheelchair ergometry with stepwise increase in work load. Result. VO 2max was significantly higher in paraplegics than in tetraplegics but significantly lower than in control subjects. Paraplegics had significantly higher low-density lipoprotein levels than both tetraplegics and control persons. The lipid profile of female tetraplegics was characterized by elevated triglycerides. An association between high-density lipoprotein levels and spinal cord injury or the level of the injury was not observed. No significant difference in lipoprotein(a) was found within SCI individuals as well as between SCI individuals and control persons indicating the predominant genetic determination of lipoprotein(a) and the thus related cardiovascular risk. Conclusion. Despite the extreme reduction of VO 2max, the assumed physical inactivity and low serum catecholamine levels due to the impairment of the sympathetic nervous system, female tetraplegic persons did not show an adverse lipoprotein profile with respect to high-density lipoprotein cholesterol levels. If the higher low-density lipoprotein cholesterol concentrations in female with spinal cord injury with low lesion levels or the elevated TG levels in female tetraplegics bare relevance with respect to an increased cardiovascular risk in this population needs to be clarified in further longitudinal investigations.

Gender disparities in serum electrolytes levels after subarachnoid hemorrhage

We retrospectively studied 133 patients with subarachnoid hemorrhage (SAH) to assess whether there was any gender disparity in serum electrolytes levels throughout the clinical course. Serum concentrations of sodium and potassium were measured in all patients, while catecholamines or antidiuretic hormone were assessed in a number of cases. Female SAH-patients had lower potassium level (3.29 ± 0.47 mEq/L) than did male patients (3.68 ± 0.38) on the first day of SAH. This gender disparity continued to the beginning of the chronic phase and disappeared several months later. Mean serum sodium level was lower in the male group than in the female group throughout the clinical course. Mean serum levels of adrenaline and antidiuretic hormone were characterized by their prominent high value on the first day. Serum potassium levels were inversely related to serum levels of catecholamines, especially adrenaline, during the acute and subacute phases, particularly on the first day.

Cytokine mRNA expression in patients with multiple sclerosis and fatigue.

Fatigue is one of the most common disabling symptoms in patients with multiple sclerosis (MS), but the putative role of proinflammatory cytokines remains to be elucidated. Thirty-seven patients (27 women, 10 men) with relapsing remitting (n = 29) and secondary progressive (n = 8) MS, aged 41.0 +/- 10.2 years, were studied. Fatigue was assessed by Krupp's Fatigue Severity Scale (FSS). Cytokine mRNA expression for interferon (IFN)-gamma tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 were measured by real time RT PCR. Autonomic function was evaluated by standard tests for parasympathetic and sympathetic function, as well as by serum levels of norepinephrine and epinephrine. Median levels of TNF-alpha mRNA expression were significantly higher in MS patients with (FSS > or = 4.0 and > or = 5.0, n = 26 and n = 14, respectively) than in those without fatigue (FSS < 4.0, n = 11). No differences were seen for IFN-gamma and IL-10 mRNA expression. Cytokine levels were not correlated to autonomic tests or to serum catecholamine levels. These results suggest that TNF-alpha, as a principal proinflammatory mediator, is associated with MS-related fatigue. This is in support of a pathogenic role of the MS-related inflammatory process in the development of fatigue.

Malignant pheochromocytoma of the urinary bladder: Effectiveness of radiotherapy in conjunction with chemotherapy

A 34-year-old Japanese man with malignant pheochromocytoma of the bladder underwent surgical resection and chemoradiotherapy for a local recurrence of lymph node metastasis. Radiotherapy seemed to be effective, indicated by the growth inhibition of the irradiated tumor, decreases in serum and urinary catecholamine levels and a clinical improvement in the refractory stage of the combined chemotherapy.

The Effects of a Tourniquet on Serum Catecholamine Levels for General and Spinal Anesthesia in Total Knee Replacement

Background: Pneumatic tourniquets are most frequently used during operations on the lower extremities, especially during knee operations, and provide a bloodless surgical field and prevent excessive blood loss. But tourniquets increase blood pressure, though the cause has not been identified. We thought that plasma catecholamine is increased by pneumatic tourniquet inflation. Troponin I is specific cardiac marker in myocardiac injury. So we measured plasma catecholamine and Troponin I under general and spinal anesthesia in patients undergoing total knee replacement. Methods: We divided the patients into two groups, the first group (Group I, n = 25) was the general anesthesia group and second group (Group II, n = 26) the spinal anesthesia group. All patients underwent an operation for total knee replacement. Serum enzyme levels are instable so we tried to keep changes at a minimal level. Thus all operations were carried out by the same group of surgeons, in the same operating room, at the same time (AM 8：00 start operation). The same tourniquet was applied for all subjects (tourniquet pressure 350 mmHg, 9 cm width). Group I patients had general anesthesia with - - Enflurane. Group II patients had spinal anesthesia with 0.5% tetracaine: the dermatomal level of sensory blockade to pin-prick was T6 - T4. We measured blood pressure, heart rate, Sp, ECG, serum catecolamine and trophonine I. Blood sampling were performed preoperation, 50 minutes after tourniquet application, and 30 minutes after operation to obtained serum catecholamine and trophonine I levesl. Result: Mean arterial pressure increased in group I during tourniquet inflation. The serum catecholamine level was higher in group I than in group II. The serum troponin I level was statistically significance in the general anesthesia groups (Group I). Conclusions: It might be suggested that an increased level of serum catecholamine causes tourniquet induced hypertension. Myocardial injury due to tourniquet induced hypertension was not affected by anesthesia type (general anesthesia or spinal anesthesia).

重症くも膜下出血の急性期治療 重症くも膜下出血急性期治療における頭蓋内および全身的複合病態の意義

To elucidate actual clinical features of patients at the poorest grade with subarachnoid hemorrhage (SAH), we studied the relation of intracranial and systemic insults. We studied 524 severely ill cases admitted within 72 hours after the onset of SAH with a Glasgow Coma Scale score (GCS) of 8 to 3 and compared them with patients with a GCS of 9 or more (907 cases) as a less ill group. As an outcome of GCS 6 is nearly the same as that of GCS 7 and significantly different from that of GCS 5, the poorest case with SAH is to be defined as those with GCS 5 or less, and a case with GCS 6 should not be regarded as Grade 5 although the WFNS grading classifies it as Grade 5. Among cases in Grade 5, some with GCS 3 on admission showed remarkable recovery, suggesting that score 3 by GCS includes improving case though it looks as GCS 3 at present. However, cases at GCS 3 who underwent resuscitation (RES) for complete cardio-pulmonary arrest all died, while some of those receiving RES for apnea without complete cardiac arrest survived. Assuming the value obtained from a simple formula [blood sugar level (mg/dl) / serum potassium concentration (mEq/L)] as stress index (SI), SI correlates well with serum catecholamine level at acute stage. This means that we can expect the extent of sympathetic tonus in acute SAH by SI, an easily and quickly calculable index. Cases with SI over 40 are seriously ill both neurologically and as to systemic complications (COMP) produced by a so-called sympathetic storm. Further deterioration with an SI over 50 is not predominantly brought about by pure SAH, but by additional hemorrhagic damage to the brain such as intracerebral hematoma or massive intraventricular hemorrhage. The severely ill group (GCS8-3) exhibited an extremely high mean SI of around 60 with or without COMP, while in the less ill group (GCS≥9) those with COMP showed a significantly higher mean SI (59) than those without (43). If the patient's neurological condition is not serious but the patient shows an SI over 60, one should pay much attention to possible cardio-pulmonary complications such as cardiac arrhythmia, heart failure or pulmonary edema.

Relationship between Brachial-Ankle Pulse Wave Velocity and Heart Rate Variability in Young Japanese Men

This study examined the relationship between arterial stiffness and autonomic nervous function in a young population. A cross-sectional study was conducted on 382 Japanese males, aged 24 to 39 years, who worked at the same information service company. Brachial-ankle pulse wave velocity (baPWV) was measured using an automatic waveform analyzer, and the spectral power of heart rate variability in the low frequency (LF: 0.04-0.15 Hz) and the high frequency (HF: 0.15-0.40 Hz) band was evaluated by the maximum entropy method. LF/HF and HF were used as the indicators of sympathetic and parasympathetic nervous activity, respectively. Psycho-hormonal responses were examined by the Profile of Mood State (tension-anxiety and anger-hostility scales) and Hamilton's Depression Scale with serum cortisol and catecholamine levels. In a univariate analysis, baPWV was positively associated with the following variables (all p <0.05): LF/HF, age, body mass index, systolic and diastolic blood pressures, heart rate, serum total cholesterol and triglycerides, blood glucose, and plasma cortisol and noradrenaline. Multiple regression analysis indicated that LF/HF was an independent predictor of baPWV (p <0.05), after controlling for significant effects of age, systolic blood pressure, and plasma noradrenaline levels. There was no significant effect of HF on baPWV in this multivariate analysis. Neither mood state nor health-related lifestyle factors such as smoking were significant. It was suggested that baPWV is closely associated with sympathetic nervous activity in young men.

Sublingual glyceryl trinitrate as prehospital treatment for hypertension in Irukandji syndrome.

TO THE EDITOR: The Irukandji syndrome can cause severe hypertension (over 220/110 mmHg)1 and has caused two fatalities from cerebrovascular haemorrhage.2 There is no first aid treatment for the severe pain or hypertension, so developing an effective prehospital treatment is a priority. The venom from the jellyfish that causes Irukandji syndrome (Carukia barnesi) is a sodium-channel agonist which causes massive release of noradrenaline. Intravenous magnesium sulfate has proven to be an effective treatment for the symptoms of Irukandji syndrome,4 but requires in-hospital monitoring. We investigated the use of sublingual glyceryl trinitrate spray (GTN), which is a vasodilator, in three sting victims, in whom it appeared to effectively control hypertension. Three patients with clinically confirmed Irukandji syndrome were given one puff of GTN sublingually for hypertension. Blood pressure (BP) was checked every minute for 5 minutes (by electronic sphygmomanometer). Further puffs of GTN were given every 5 minutes, with the aim of reducing the diastolic pressure below 100 mmHg. The treatment and clinical course of each patient is described. ■ Patient 1 was a 43-year-old man with severe Irukandji syndrome (adrenergic symptoms, severe low-back and muscular pains) who presented 40 minutes after Carukia barnesi envenomation on an island in the Whitsundays. Despite being given 10 mg morphine intravenously, his BP was 200/112 mmHg. One puff of GTN was given, and after 5 minutes his BP was 180/120 mmHg; another puff reduced it to 170/ 110 mmHg, and 10 minutes after a third puff it was 160/100 mmHg. After transfer to a mainland hospital, his clinical course was stormy. His hypertens ion was poorly contro l led by intravenous magnesium and he required intravenous nitrates and morphine. ■ Patient 2 was a 49-year-old man with pain (for which 10mg morphine and 50 mg promethazine were given intramuscularly), adrenergic symptoms and a BP of 182/110 mmHg 25 minutes after Carukia barnesi envenomation on a Whitsunday Island. One puff of GTN reduced his BP to 170/96 mmHg within 5 minutes; a second puff reduced it to 140/90mmHg at a further 5 minutes. His BP remained at this level until he was transferred to hospital an hour later. ■ Patient 3 was a 33-year-old woman with pain (treated with 10 mg morphine and 50 mg promethazine given intramuscularly), adrenergic symptoms and mild hypertension (143/98 mmHg) 35 minutes after Carukia barnesi envenomation on the same Whitsunday Island. She was given three puffs of GTN, which reduced her BP to 130/80 mmHg after 30 minutes. None of the three patients had preexisting hypertension, or took medication. GTN reduces hypertension by vasodilation, and is now recommended for hypertension from dysreflexia in patients with spinal injury, in whom similar high levels of serum catecholamines occur. Further assessment of GTN use in patients with Irukandji syndrome is necessary, but we believe it should be considered as prehospital treatment under medical guidance. It is currently the recommended treatment by Ambulance Officers in the Queensland Ambulance Service.6

Prolonged effects of polyriboinosinic:polyribocytidylic acid on spontaneous running wheel activity and brain interferon-α mRNA in rats: a model for immunologically induced fatigue

Following 2 weeks acclimation to the running wheel in the home cages, an i.p. injection of a synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly I:C, 3 mg/kg), was performed to produce the immunologically induced fatigue in rats. The daily amounts of spontaneous running wheel activity decreased to about 40–60% of the preinjection level until day 9 with normal circadian rhythm, then gradually returned to the baseline level by day 14. Rats given a heat exposure (36 °C for 1 h) for the consecutive 3 days showed an increase in activity except for the first day. In the open field test, the total moving distance and the number of rearing of the poly I:C-injected rats decreased on day 1, but they were not different from the saline-injected group on day 7, suggesting that the poly I:C-induced fatigue on day 7 was not due to the peripheral problems such as muscle/joint pain, but involved the CNS. Quantitative analysis of mRNA levels using a real-time capillary reverse transcriptase-polymerase chain reaction (RT-PCR) method revealed that interferon-α (IFN-α) mRNA contents in the cortex, hippocampus, hypothalamic medial preoptic, paraventricular, and ventromedial nuclei were higher in the poly I:C group than those in the saline and heat-exposed groups on day 7, although the amount of interleukin-1β mRNA showed no differences. Serum adrenocorticotropic hormone and catecholamine levels were not significantly different between groups. The present results indicate that the prolonged fatigue induced by poly I:C, which is evaluated by the spontaneous running wheel activity, can be used as an animal model for the immunologically induced fatigue associated with viral infection, and suggest that brain IFN-α may play a role in this model.

Comparison of gastric peristalsis inhibition by scopolamine butylbromide and glucagon: evaluation by electrogastrography and analysis of heart rate variability

Activation of glucagon receptors of the smooth muscle membrane suppresses gastric peristalsis. We evaluated autonomic nervous activity by two methods, electrogastrography (EGG) and analysis of heart rate variability, to compare the inhibiting effects of glucagon and scopolamine butylbromide on gastric peristalsis. Heart rate variability, EGG, and blood catecholamine levels were measured before and after administration of glucagon (G group), scopolamine butylbromide (SB group), or physiological saline (C group). Autonomic nervous function was evaluated using spectral analysis of heart rate variability, and low frequency (LF) and high frequency (HF) power; the LF/HF ratios were also determined. After administration of scopolamine butylbromide, HF power, an index of parasympathetic nervous activity, decreased; and the LF/HF ratio, an index of sympathetic nervous activity, increased. In contrast, no significant change was observed in autonomic nervous activity after administration of glucagon. The peak power amplitudes of the EGG decreased significantly in the G and SB groups after intramuscular injection, but the difference between the groups was not significant. Furthermore, the dominant frequency increased significantly in the G and SB groups after injection. Serum catecholamine levels showed no significant changes after administration of scopolamine butylbromide or glucagon. Inhibition of gastric peristalsis by glucagon via glucagon receptors on smooth muscles did not influence autonomic nervous activity, unlike the results obtained after administration of scopolamine butylbromide. Therefore, glucagon may be safe for use with elderly patients and those with cardiopulmonary complications.

Malignant pheochromocytoma associated with pseudo-obstruction of the colon

Effective treatment has not yet been established for intestinal pseudo-obstruction, a rare complication of malignant pheochromocytoma. We report the case of a 41-year-old man who presented with malignant pheochromocytoma associated with pseudo-obstruction of the colon. His serum catecholamine level was markedly elevated, and his large intestine was distended with gas and lodged stool. Laxatives and enemas were not effective in relieving his symptoms. We subsequently performed an ileostomy, after which the patient had good bowel movement and was able to resume oral food intake.

Induction and maintenance of an experimental model of severe cardiomyopathy with a novel protocol of rapid ventricular pacing

Objective: An animal model of chronic severe heart failure is needed to evaluate new mechanical devices, surgical procedures, and medical therapies. The purpose of this study was to evaluate a unique new model of severe heart failure developed by means of a novel protocol of rapid ventricular pacing. Methods: Heart failure was induced in 8 mongrel dogs by means of rapid ventricular pacing (230 beats/min) for 4 weeks. After a sham operation, maintenance pacing at a reduced rate (190 beats/min) was continued for another 4 weeks. Results: Left ventricular systolic function was significantly reduced at week 4 and remained low at week 8, including the slope of the end-systolic pressure-volume relationship (2.4 ± 1.0 vs 0.7 ± 0.2 vs 0.8 ± 0.3 mm Hg/mL [baseline vs week 4 vs week 8, respectively]), ejection fraction (63% ± 5% vs 28% ± 7% vs 33% ± 5%), and cardiac output (3.1 ± 0.7 vs 2.0 ± 0.3 vs 2.2 ± 0.7 L/min). Significant ventricular remodeling changes took place with increased ventricular volumes and circumferential wall stress, which were stable between weeks 4 and 8. Serum catecholamine and atrial natriuretic polypeptide levels also increased from baseline but stabilized between weeks 4 and 8. The end-diastolic pressure-volume relationship also showed stable diastolic function between weeks 4 and 8. Conclusions: Induction pacing at 230 beats/min readily created severe heart failure in all animals, and a new technique of maintenance pacing provided a consistent model of severe heart failure. This model can be used to study a variety of new interventions for heart failure.J Thorac Cardiovasc Surg 2002;123:544-9