Abnormal Cardiovascular Responses Research Articles

Abnormal respiratory patterns in a series of post-concussive patients

BackgroundAutonomic nervous system dysfunction has been identified in patients following traumatic brain injury (TBI), including concussion. Abnormal postural heart rate and blood pressure instability have been identified in post-concussive patients. Recently, we have identified abnormal respiratory patterns during autonomic testing for post-concussive symptoms. Tachypnea is a clinical feature of autonomic instability in paroxysmal sympathetic hyperactivity following severe TBI and the purpose of this study is to identify abnormal respiratory patterns in patients with autonomic nervous system impairment following mild TBI.MethodsA retrospective review of patients in the Mayo Clinic Arizona Concussion Program from October 2017 to March of 2018 was performed. Clinical features and autonomic testing were reviewed. Autonomic testing included blood pressure and heart rate responses to Valsalva, heart rate variability during deep breathing, blood pressure and heart rate responses to head-up tilt, sudomotor testing, and respiratory responses using respiratory inductive plethysmography. Patients with co-morbidities or medications with potential to influence autonomic testing were excluded.ResultsFifteen patients with a history of concussion were studied. Nine of 15 patients had abnormal cardiovascular responses on autonomic testing, typically excessive postural tachycardia with head-up tilt. Abnormal respiratory patterns were identified in 8 of 9 patients with abnormal autonomic testing and in 3 of 6 patients without other abnormalities on autonomic testing. A number of different respiratory patterns were identified including tachypnea, prolonged apneic episodes, Cheyne-Stokes, and other unusual respiratory patterns.ConclusionWe have identified abnormal respiratory patterns in a series of concussion patients with or without other signs of dysautonomia. Tachypnea has been previously reported as a clinical feature of paroxysmal sympathetic hyperactivity following severe TBI and was present in some patients in this series. The clinical significance and mechanisms involved in the generation of respiratory dysrhythmia require further study, but may be another manifestation of post-concussive dysautonomia.

Athlete's Heart: Diagnostic Challenges and Future Perspectives.

Distinguishing between adaptive and maladaptive cardiovascular response to exercise is crucial to prevent the unnecessary termination of an athlete's career and to minimize the risk of sudden death. This is a challenging task essentially due to the substantial phenotypic overlap between electrical and structural changes seen in the physiological athletic heart remodeling and pathological changes seen in inherited or acquired cardiomyopathies. Stress testing is an ideal tool to discriminate normal from abnormal cardiovascular response by unmasking subtle pathologic responses otherwise undetectable at rest. Treadmill or bicycle electrocardiography, transthoracic echocardiography, and cardiopulmonary exercise testing are common clinical investigations used in sports cardiology, specifically among participants presenting with resting electrocardiographic abnormalities, frequent premature ventricular beats, or non-sustained ventricular arrhythmias. In this setting, as well as in cases of left ventricular hypertrophy or asymptomatic left ventricular dysfunction, stress imaging and myocardial tissue characterization by cardiovascular magnetic resonance show promise. In this review, we aimed to reappraise current diagnostic schemes, screening strategies and novel approaches that may be used to distinguish adaptive remodeling patterns to physical exercise from early phenotypes of inherited or acquired pathological conditions commanding prompt intervention.

Abstract P294: Intergenerational Obesity: Impact on Cardiac Function and Reserve in Mice Fed a High Fat Diet

Obesity is associated with structural and functional changes in the heart and abnormal cardiovascular responses to exercise in humans and experimental animals. However, the impact of intergenerational obesity on cardiac function and reserve during increased stress is still unknown. In this study we examined if intergenerational obesity alters cardiac function and responses to a stress test induced by dobutamine in 22-week-old male lean mice fed a control diet (n=5) and obese mice fed a high fat diet (HFD) after birth and that were offspring of mothers who were fed a HFD (F1-HFD, n=7). Mice were instrumented with venous catheters for continuous infusion of saline and progressively increasing doses of dobutamine (2-12 ng/g/min, 2 min at each dose). Long and short axis left ventricle dimensions were obtained before and one minute after each dose of dobutamine using a 30 MHZ transducer (VEVO3100). Baseline heart rate (HR) was similar in F1-HFD (388±15 bpm) and control (426±22 bpm). Compared to controls, F1-HFD mice exhibited impaired diastolic function (E’/A’ ratio: 0.9±0.1 vs. 1.4±0.1 mm/s and isovolumetric relaxation time: 30±2 vs. 21±1 ms) but increased baseline ejection fraction (EF) (84±1 vs. 64±4 %). Dobutamine infusion increased HR by 6±3 and 41±11 bpm, and EF (84±1 to 93±2 and 64±4 to 94±2 %) in F1-HFD and controls, respectively. These results indicate that intergenerational obesity is associated with diastolic dysfunction, but no major alterations in cardiac reserve in response to a cardiovascular stress test. (NHLBI-PO1HL51971, NIGMS P20GM104357 and U54GM115428)

Insulin Potentiates Neuronal Responses to Chemical Stimulation in Thin Muscle Afferents and Dorsal Root Ganglia

The cardiovascular response to physical activity is abnormally exaggerated in patients with type 2 diabetes mellitus (T2D). Recent studies in patients with T2D have suggested that this exaggerated responsiveness is mediated, in part, by the skeletal muscle metaboreflex. However, the mechanisms causing augmentations in muscle metaboreflex function in this disease remain to be elucidated. Chronic hyperinsulinemia associated with peripheral insulin resistance is one of the pathophysiological characteristics of T2D. Evidence suggests that transient receptor potential vanilloid receptors, which contribute to metaboreflex activation, are more responsive to stimuli in the presence of insulin. Given that metaboreflex afferent fibers reside in skeletal muscle, it is suggested that hyperinsulinemia may underlie the skeletal muscle metaboreflex overactivity manifest in T2D. PURPOSE: To examine the impact of insulin on neuronal responses to chemical stimulation in thin muscle afferents and dorsal root ganglia (DRG) of normal healthy rodents. It was hypothesized that insulin potentiates the activity of metabolically sensitive afferent neurons. METHODS: Chemically activated neurons were assessed by single-fiber recordings from rat muscle-nerve preparations in vitro and by whole cell patch-clamp recordings from cultured mice DRG neurons. The magnitude of responses to capsaicin stimulation and the capsaicin activated current were recorded, respectively. RESULTS: Compared to control conditions, thin muscle afferent response magnitude was significantly increased by insulin exposure (0.03±0.03 vs. 0.25±0.02 imp, n=3, P<0.05). In DRG cell culture, total charge transfer by capsaicin activated current was largely augmented by insulin administration (403±159 % changes from control conditions, n=3, P=0.11). CONCLUSIONS: These data demonstrate that thin muscle afferent as well as DRG neuronal responses to capsaicin are augmented by insulin exposure in normal healthy animals. The data support the concept that chronic hyperinsulinemia may potentiate skeletal muscle metaboreflex function in T2D contributing to the abnormal cardiovascular response to exercise characteristic of this disease. Supported by the Lawson & Rogers Lacy Research Fund in Cardiovascular Disease and JSPS KAKENHI JP17K01769

Neural Responses to Mechanical Stimulation in Thin Muscle Afferents and Dorsal Root Ganglia are Sensitized by Insulin

In patients with type 2 diabetes mellitus (T2D), the circulatory responses to physical activity are abnormally exaggerated. Recent studies in patients with T2D have suggested that this exaggerated cardiovascular response is mediated, in part, by the exercise pressor reflex (EPR) which is a primary contributor to autonomic cardiovascular control during exercise. However, the mechanisms underlying this abnormal EPR function in T2D remain unknown. The pathophysiology of T2D is characterized by insulin resistance induced hyperinsulinemia. Further, evidence suggests that insulin increases the sensitivity of transient receptor potential vanilloid receptors localized to muscle afferent neurons that contribute to EPR activation. Importantly, sensitization of muscle receptors associated with the mechanically sensitive component of the EPR (i.e. the muscle mechanoreflex) has been shown to mediate reflex overactivity in other cardiovascular disease states such as heart failure and hypertension. Given this information, it is logical to suggest that excess levels of insulin may potentiate mechanoreflex function in T2D.PURPOSETo examine the effect of insulin on neuronal responses to mechanical stimulation in thin muscle afferents and dorsal root ganglia (DRG) of normal healthy rodents. We hypothesized that insulin sensitizes the activity of mechanically sensitive afferent neurons.METHODSMechanically activated neurons were assessed before (control) and after exposure to insulin 1) by single‐fiber recordings from rat muscle‐nerve preparations in vitro and 2) by whole cell patch‐clamp recordings from cultured mice DRG neurons. The magnitude of the response to mechanical stimulation as well as the mechanical threshold were assessed.RESULTSCompared to control, the mechanical threshold of thin muscle afferents was significantly decreased after insulin administration (58±16 vs. 15±17 mN, n=8, P&lt;0.05) while the response magnitude was not changed (66±22 vs. 68±16 spikes, n=8). In DRG cell culture, mechanically activated current was significantly augmented by insulin (−93 ±12 vs. −190±43 pA, n=16, P&lt;0.05) whereas the mechanical threshold was significantly decreased (4.6±0.4 vs. 2.6±0.3 steps, n=17, P&lt;0.05). Further, after pretreatment of DRG insulin receptors with the inhibitor GSK1838705, insulin failed to augment the mechanically activated current (−91±19 vs. −92±19 pA, n=14) or to reduce the mechanical threshold (3.5 ± 0.4 vs. 3.4 ± 0.5 steps, n=11).CONCLUSIONSThese data demonstrate that thin muscle afferent and DRG neuronal responses to mechanical stimulation are sensitized by the presence of insulin in normal healthy animals. Importantly, the findings provide support for the concept that chronic hyperinsulinemia enhances skeletal muscle mechanoreflex function in T2D contributing to the abnormal cardiovascular response during exercise in this disease.Support or Funding InformationSupported by the Lawson &amp; Rogers Lacy Research Fund in Cardiovascular Disease and JSPS KAKENHI JP17K01769This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Exercise response in Parkinson’s disease: insights from a cross-sectional comparison with sedentary controls and a per-protocol analysis of a randomised controlled trial

ObjectivesTo investigate the acute and adaptation cardiovascular and metabolic training responses in people with Parkinson’s disease (pwP).Design(1) A cross-sectional study of exercise response of pwP compared with sedentary controls and...

Exaggerated cardiovascular responses to treadmill running in rats with peripheral arterial insufficiency.

Patients with atherosclerotic peripheral artery disease have an augmented pressor response to treadmill walking, but the underlying mechanisms remain poorly understood and difficult to isolate because of the confounding presence of numerous cardiovascular risk factors. In the present study, we tested the hypothesis that a chronic deficit in muscle blood flow capacity would be sufficient to trigger an exaggerated pressor response to dynamic exercise. Sprague-Dawley rats (5 male and 5 female) were instrumented with radiotelemetry devices to measure the cardiovascular responses to treadmill running before and after bilateral femoral artery ligation, which has been previously shown to reduce the blood flow capacity of distal hindlimb muscles by >60%. Treadmill running evoked reproducible increases in mean arterial pressure (MAP) and heart rate (HR), which were significantly augmented 3 days after femoral artery ligation in both male rats [ΔMAP: +10 ± 1 (SE) vs. +18 ± 3 mmHg and ΔHR: +94 ± 12 vs. +148 ± 15 beats/min, P < 0.05] and female rats (ΔMAP: +16 ± 3 vs. +30 ± 5 mmHg and ΔHR: +128 ± 20 vs. +178 ± 19 beats/min, P < 0.05). Similar exaggerated MAP and HR responses were observed at repeated intervals between 3 and 65 days postligation. These findings indicate that a chronic deficit in muscle blood flow capacity is an important, persistent cause of the abnormal pressor and cardioaccelerator responses to dynamic exercise in both male and female rats with peripheral arterial insufficiency. NEW & NOTEWORTHY Using radiotelemetry to assess cardiovascular effects of exercise, we showed that femoral artery obstruction in male and female rats is an important, persistent cause of exaggerated pressor and cardioaccelerator responses to treadmill running. This translational model reproduces the abnormal cardiovascular response to exercise seen in patients with peripheral artery disease. Listen to this article's corresponding podcast at http://ajpheart.podbean.com/e/treadmill-bp-in-simulated-peripheral-artery-disease/ .

Insulin resistance, serum uric acid and metabolic syndrome are linked to cardiovascular dysfunction in pediatric obesity.

Childhood obesity is associated with cardiovascular abnormalities but little is known on the potential correlation between early cardiovascular and metabolic alterations. Aims of this study were 1) to evaluate early cardiovascular abnormalities in a large population of obese children and adolescents compared with a normal weight counterpart, 2) to investigate their potential association with insulin resistance (IR), serum uric acid (sUA) and metabolic syndrome (MetS). This was a single-center case-control study. Eighty obese (OB) subjects (6-16years) and 20 normal weight (NW) matched controls were consecutively recruited. In the whole population we performed an anthropometric and a cardiovascular assessment. OB patients also underwent an OGTT and biochemical evaluations. OB children showed greater left atrial (LA) and ventricular (LV) dimensions and mass and higher carotid artery intima-media thickness (CIMT), compared with NW controls. The BMI z-score, waist circumference, IR and sUA were positively related with LA and LV dimensions and mass. OB subjects with MetS (46.3%) showed greater LA diameter (p=0.001) and LV area (p=0.01) and volume (p=0.04) compared with OB children without MetS. LA diameter and LV dimensions and mass were significantly dependent on the number of criteria for MetS. Mets, sUA and IR were significant predictors of left heart dimensions and mass in obese children. Obesity and MetS are associated with abnormal cardiovascular response during childhood. Hyperuricemia can be an early marker of cardiovascular dysfunction and the routine determination of circulating levels of sUA should be implemented during risk stratification among pediatric age.

Abstract P294: Leptin Deficiency Reduces Cardiac Reserve Independently of Increased Body Weight

Obesity is associated with structural and functional changes in the heart and abnormal cardiovascular responses to exercise in humans and experimental animals. We and others have demonstrated that specific deletion of cardiomyocyte leptin receptors causes cardiac dysfunction associated with decreased energy production in the heart. However, the importance of leptin in normal cardiac reserve during increased stress is still unknown. In this study we examined if leptin deficiency, independently of obesity, alters cardiovascular responses to a stress test induced by dobutamine in 20 week old non-obese ob/ob mice (n=4, 30±2g) that were pair-weighted to match the body weight of wild type (WT) control mice (n=5, 31±3g), and obese ob/ob mice fed ad-lib (n=4, 65±4g). An additional group of non-obese ob/ob mice (n=4) was infused with leptin via osmotic minipump (4 μg/kg/min, IP) for 7 days. Mice were instrumented with for continuous infusion of saline and progressively increasing doses of dobutamine (2-12 ng/g/min, 2 min at each dose). Long and short axis left ventricle dimensions were obtained before and one minute after each dose of dobutamine using a 30 MHZ transducer (VEVO2100®). Baseline heart rate (HR) was similar in obese ob/ob (431±24 bpm) and WT control (421±28 bpm) mice, but significantly reduced in non-obese ob/ob (356±28 bpm) mice. Compared to WT mice, non-obese ob/ob mice had no significantly differences in baseline ejection fraction (EF) (76±4 vs. 66±4%) but higher EF was observed in obese ob/ob (83±3%) mice. Dobutamine infusion increased average delta HR by 42±7, 104±16 and 37±11 bpm, and EF by 24.8±1.2, 4.9±0.5 and 33.3±0.8 % in WT, non-obese ob/ob and obese ob/ob mice, respectively. Chronic leptin replacement restored EF response to dobutamine in non-obese ob/ob mice (93±2 vs. 94±2% in WT mice). These results show that leptin deficiency leads to reduced myocardial reserve independent of changes in body weight, and leptin replacement in non-obese ob/ob mice completely restored EF response to cardiovascular stress test.

The Role of Cardiopulmonary Exercise Testing for Decision Making in Patients with Repaired Tetralogy of Fallot.

Tetralogy of Fallot is the most common form of cyanotic congenital heart disease. As a result of the surgical strategies employed at the time of initial repair, chronic pulmonary regurgitation (PR) is prevalent in this population. Despite sustained research efforts, patient selection and timing of pulmonary valve replacement (PVR) to address PR in young asymptomatic patients with repaired tetralogy of Fallot (rToF) remain a fundamental but as yet unanswered question in the field of congenital heart disease. The ability of the heart to compensate for the chronic volume overload imposed by PR is critical in the evaluation of the risks and benefits of PVR. The difficulty in clarifying the functional impact of PR on the cardiovascular capacity may be in part responsible for the uncertainty surrounding the timing of PVR. Cardiopulmonary exercise testing (CPET) may be used to assess abnormal cardiovascular response to increased physiologic demands. However, its use as a tool for risk stratification in asymptomatic adolescents and young adults with rToF is still ill-defined. In this paper, we review the role of CPET as a potentially valuable adjunct to current risk stratification strategies with a focus on asymptomatic rToF adolescents and young adults being considered for PVR. The role of maximal and submaximal exercise measurements to identify young patients with a decreased or borderline low peak VO2 resulting from impaired ventricular function is explored. Current knowledge gaps and research perspectives are highlighted.

Abnormal cardiovascular response to exercise in hypertension: contribution of neural factors.

During both dynamic (e.g., endurance) and static (e.g., strength) exercise there are exaggerated cardiovascular responses in hypertension. This includes greater increases in blood pressure, heart rate, and efferent sympathetic nerve activity than in normal controls. Two of the known neural factors that contribute to this abnormal cardiovascular response are the exercise pressor reflex (EPR) and functional sympatholysis. The EPR originates in contracting skeletal muscle and reflexly increases sympathetic efferent nerve activity to the heart and blood vessels as well as decreases parasympathetic efferent nerve activity to the heart. These changes in autonomic nerve activity cause an increase in blood pressure, heart rate, left ventricular contractility, and vasoconstriction in the arterial tree. However, arterial vessels in the contracting skeletal muscle have a markedly diminished vasoconstrictor response. The markedly diminished vasoconstriction in contracting skeletal muscle has been termed functional sympatholysis. It has been shown in hypertension that there is an enhanced EPR, including both its mechanoreflex and metaboreflex components, and an impaired functional sympatholysis. These conditions set up a positive feedback or vicious cycle situation that causes a progressively greater decrease in the blood flow to the exercising muscle. Thus these two neural mechanisms contribute significantly to the abnormal cardiovascular response to exercise in hypertension. In addition, exercise training in hypertension decreases the enhanced EPR, including both mechanoreflex and metaboreflex function, and improves the impaired functional sympatholysis. These two changes, caused by exercise training, improve the muscle blood flow to exercising muscle and cause a more normal cardiovascular response to exercise in hypertension.

Two-dimensional echocardiographic evaluation in liver cirrhosis patients in prediction of cirrhotic cardiomyopathy

Background/Aim. Cirrhotic cardiomyopathy (CCM) is a clinical syndrome in liver cirrhosis (LC) patients, which is characterized by the abnormal cardiovascular (CV) response to physiologic, pathologic, or pharmacologic stress provocation, but normal to increased cardiac output and contractility at rest. The aim of the study was to identify the structural and functional myocardial changes in patients with LC of various origins in advanced stages of the disease, by transthoracic two-dimensional echocardiography Doppler imaging evaluation in the prediction of CCM. Methods. The research was performed as a prospective, nest case-control study, on carefully selected 40 patients in the advanced stage of LC and negative personal medical history on previous CV disease and 40 healthy subjects as the control, from January 2012?December 2014. There were determining significant echocardiographic parameters in LC patients as predictors for the development and/or presence of CCM. Results. Most of the LC patients were alcoholic (80%), dominantly in Child-Pough C stage of the disease (70%). The average value of QT interval in the LC patients was significantly higher (0.44 ? 0.03 ms vs 0.42 ? 0.01 ms; p &lt; 0.001), as well as brain natriuretic peptide (BNP) serum level (284.61 ? 181.44 ng/L vs 69.41 ? 31.08 ng/L; p &lt; 0.001) compared to those in the healthy subjects. A significant association with serum BNP level in LC patients was shown with left atrial diameter (p = 0.031), left ventricular ejection fraction (p = 0.014), pulmonary artery systolic pressure (PASP) (p = 0.000) and the presence of tricuspid valve regurgitation of 2+ (p = 0.000), affecting its change of 41.6%. Conclusion. The obtained results suggest that LC patients have significant echocardiographic signs of myocardial dysfunction, as well as the increased BNP serum level. Left atrial diameter, left ventricular ejection fraction, PASP and tricuspid valve regurgitation are valuable echocardiographic predictors of CCM.

PP.24.16] CORRELATION BETWEEN PULSE WAVE VELOCITY AND HEART RATE VARIABILITY IN PREGNANT WOMEN WITH PREECLAMPSIA

Objective: To investigate the correlation between pulse wave velocity (PWV) and heart rate variability (HRV) in pregnant women with preeclampsia (PE). Pulse wave velocity (PWV) is the most popular index to assessment the arterial stiffness Design and method: The analysis was performed in 155 women, mean age- 26–42 years with PE and 10 with normal blood pressure volunteers. The PWV were exanimate a non-invasive digital volume pulse (DVP) measuring system using a dual channel simultaneous measurement method. The changes of systolic and diastolic blood pressure and of pulse rate after active standing were registered noninvasive. The RR intervals were recorded by means of MP 100 computerizes system with ECG module and the maximal –minimal interval during deep breathing (HRdb), the Valsalva ration (VR), and the 30:15 ratio were calculated automatically. Results: The PWV of CH group is significantly higher than those of normal blood pressure. (P < 0.05), the reflexion index (RI) and arterial stiffness index (SI) parameters in PE group are markedly higher than those in controls. RR variability is positively related with PWV in two groups, but the correlation in PE group is better than those in controls. Our results reveal abnormal cardiovascular responses with significant decrease of the HRdb response, the VR and the 30:15 ratios in the patients in comparison to the controls. The abnormalities were asymptomatic in 59% of the patients. Conclusions: PWV should be as another important clinic index to evaludte PE risk and the effect of PE treatment during pregnancy.

Influence of Low Peak Respiratory Exchange Ratio on Cardiac Rehabilitation in Patients With Coronary Artery Disease.

ObjectiveTo compare and analyze the effects of cardiac rehabilitation (CR) in two groups based on the peak respiratory exchange ratio (RERpeak) 1.1 values using the exercise tolerance test (ETT) results, and to investigate the reasons for early termination of ETT.MethodsPatients with acute coronary syndrome who participated in CR exercise training were selected and all subjects underwent 6 weeks of CR exercise training. ETT was performed on a treadmill using a Modified Bruce Protocol before and after CR exercise training. According to the result of the first ETT, the subjects were divided into two groups: those with an RERpeak≥1.1 (n=33) and those with an RERpeak<1.1 (n=22). We investigated the reasons for ETT termination and compared the effect of CR between the groups.ResultsThe reasons for the early termination of the first ETT in the RERpeak<1.1 group were subjective dyspnea, abnormal cardiovascular responses, leg fatigue and other problems. After a 6-week CR, the peak oxygen consumption (VO2peak) and ETT time increased, and the rate of perceived exertion (RPE) and RPP (rate pressure product) at stage 3 decreased in both the RERpeak<1.1 and RERpeak≥1.1 groups.ConclusionCR exercise training improved exercise capacity, not only in the RERpeak≥1.1 group, but also in the RERpeak<1.1 group. This means that patients with a lower exercise tolerance could also benefit from the effects of CR. Thoughtful consideration to identify the direct and indirect causes for the early termination of ETT would be necessary to improve the efficiency of CR.

Double Inlet Single Ventricle With Transposition of the Great Arteries and Situs Inversus With Dextrocardia in an Adult Without Surgical Correction: Challenges and Triumphs

SESSION TITLE: Cardiovascular Disease Case Report Posters SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM INTRODUCTION: Single ventricle abnormality represents approximately 1% of all congenital cardiac defects, with an incidence of 0.05-0.1:10'000 live births [1]. With current medical and surgical advances, more patients are surviving to adulthood. Acute decompensation in adults is a common cause of death. New corrective approaches should be entertained to support the failing single ventricular hearts [2, 3] CASE PRESENTATION: We present a case of a 61 year old female with unrepaired cyanotic congenital heart disease. Her defect is significant for double inlet single ventricle with left looping and transposition of great arteries and situs inversus with dextrocardia, with somewhat “protected” pulmonary bed secondary to pulmonary stenosis (PS). The patient has done well, despite developing atrial fibrillation and worsening atrioventricular valve regurgitation and complete heart block. TEE confirmed well preserved systolic function with EF 54%, severe PS and severe biatrial enlargement. Right and Left catheterization notable for within normal limits coronary flow and high normal pulmonary artery pressures. Cardiopulmonary testing is significant for abnormal cardiovascular response - inability to augment stroke volume and increased oxygen consumption with submaximal exercise response. Multidisciplinary decision was made to proceed with epicardial pacemaker (EPM). After uneventful minimal inferior medial sternotomy approach for placement and uncomplicated CTICU recovery our patient is undergoing evaluation for orthotopic heart transplant DISCUSSION: The goal of EPM placement was to improve the patient's choronotropic incompetence and respectively functional capacity. After initial post-operative recovery, patient noted improved functional status and oxygen saturation in high to low 70s CONCLUSIONS: The uncorrected complex adult cyanotic cardiac pathology offers multifactorial array of challenges to the treating team. Understanding of the anatomy and pathological complications, as well as the physiological adaptation of each patient's condition, is essential for the optimum management of these intricate disorders Reference #1: EK Steinberger, C Ferencz, CA Loffredo. Infants With Single Ventricle:A Population-Based Epidemiological Study. Teratology.2002;65:103-115 Reference #2: Rossano JW, Chang AC.Perioperative management of patients with poorly functioning ventricles in the setting of the functionally univentricular heart. Cardiol Young.2006;16 (S1):47-54 Reference #3: H Vyas, DJ Hagler. Double Inlet Left Ventricle. Cur Treat Opt Card Med.2007;9:391-398 DISCLOSURE: The following authors have nothing to disclose: Ntesi Asimi, Jane Wilcox, Sherif Afifi No Product/Research Disclosure Information

Impaired Baroreflex Function in Mice Overexpressing Alpha-Synuclein

Cardiovascular autonomic dysfunction, such as orthostatic hypotension consequent to baroreflex failure and cardiac sympathetic denervation, is frequently observed in the synucleinopathy Parkinson’s disease (PD). In the present study, the baroreceptor reflex was assessed in mice overexpressing human wildtype alpha-synuclein (Thy1-aSyn), a genetic mouse model of synucleinopathy. The beat-to-beat change in heart rate (HR), computed from R–R interval, in relation to blood pressure was measured in anesthetized and conscious mice equipped with arterial blood pressure telemetry transducers during transient bouts of hypertension and hypotension. Compared to wildtype, tachycardia following nitroprusside-induced hypotension was significantly reduced in Thy1-aSyn mice. Thy1-aSyn mice also showed an abnormal cardiovascular response (i.e., diminished tachycardia) to muscarinic blockade with atropine. We conclude that Thy1-aSyn mice have impaired basal and dynamic range of sympathetic and parasympathetic-mediated changes in HR and will be a useful model for long-term study of cardiovascular autonomic dysfunction associated with PD.

1002 CORRELATION BETWEEN PULSE WAVE VELOCITY AND HEART RATE VARIABILITY IN YOUNG PATIENTS WITH ISOLATED SYSTOLIC HYPERTENSION

Aim: To investigate the correlation between pulse wave velocity (PWV) and heart rate variability (HRV) in young patients with isolated systolic hypertension (ISH). PWV is the most popular index to assessment the arterial stiffness1,2. Material and Methods: The analysis was performed in 45 patients -22 men and 23 women mean age- 21-40 years with isolated systolic hypertension and 10 volunteers. The PWV were exanimate a non-invasive digital volume pulse (DVP) measuring system using a dual channel simultaneous measurement method. The changes of systolic and diastolic blood pressure and of pulse rate after active standing were registered noninvasive (Colin 7000, USA). The RR intervals were recorded by means of MP 100 computerizes system with ECG module (Byopac System Inc.,USA) and the maximal –minimal interval during deep breathing (HRdb), the Valsalva ration (VR), and the 30:15 ratio were calculated automatically. Results: The PWV of ISH group is significantly higher than those with normals (P < 0.05), the reflexion index (RI) and arterial stiffness index (SI) parameters in ISH group are markedly higher too. RR variability is positively related with PWV in two groups, but the correlation in ISH group is better than those in controls. Our results reveal abnormal cardiovascular responses with significant decrease of the HRdb response, the VR and the 30:15 ratios in the patients in comparison to the controls. The abnormalities were asymptomatic in 59% of the patients. Conclusion: PWV should be as another important clinic index to evaludte ISH risk and the effect of ISH treatment to young patients. Autonomic nerve function disorder may be lead to ISH. References Asmar R, Benetos A, Topouchian J, Laurent P, Pannier B, Brisac AM, Target R, Levy BI. Assessment of arterial distensibility by automatic pulse wave velocity measurement: validation and clinical application studies. Hypertension. 1995;26:485–490. Blacher J, Asmar R, Djane S, London GM, Safar ME. Aortic Pulse Wave Velocity as a Marker of Cardiovascular Risk in Hypertensive Patients. Hypertension. 1999;33:1111-1117.

Abnormalities of the Exercise Pressor Reflex in Heart Failure

Abnormal cardiovascular responses to exercise in heart failure contribute significantly to the morbidity and mortality in the patient population. These abnormal responses may be the result of peripheral impairment in the skeletal muscle and the neurons that innervate the muscle. We present the current literature on the role of muscle afferents in regulating the cardiovascular responses to exercise in cardiomyopathy.

Cardiovascular Responses During Constant Load Walking in Patients with Peripheral Arterial Disease

Exaggerated increases in heart rate and blood pressure are abnormal cardiovascular responses during constant load walking in peripheral arterial disease (PAD) patients, and are markers of hemodynamic instability and increased cardiovascular risk. However, predictors of changes in heart rate and blood pressure are poorly described. Purposes. To assess the cardiovascular responses during constant load walking, and to identify predictors of this response in PAD patients. Methods. Seventy-nine patients with PAD performed a constant load treadmill test (2 mph, 0% grade). During the test, systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and rate pressure product (RPP) were obtained at the fourth minute to the last minute of walking. Patients were also characterized on demographic measures, cardiovascular risk factors, baseline exercise performance measures, and vascular measures. Results. During constant load walking, there was a significant increase (p < 0.01) in SBP (+12 ± 10 mmHg), DBP (+6 ± 9 mmHg), HR (+5 ± 5 bpm) and RPP (+1920 ± 1435 mmHg x bpm). The HR and RPP responses were negatively correlated with ischemic window (r= -0.23 and r= -0.26, respectively; p<0.05) and positively correlated with the HR during the first minute of recovery from maximal graded exercise (r= 0.27 and r= 0.24, respectively; p<0.05). The increase in cardiovascular variables during walking was greater in subjects with higher BMI and in men (p < 0.05). Conclusion. Patients with PAD have an increased cardiovascular response during constant load walking, and these responses are greater in obese patients and in men. The clinical implication is that PAD patients engaged in walking training programs, particularly obese men, require frequent assessment of cardiovascular parameters to avoid exaggerated increases in BP, HR and RPP during constant work load walking. Funding by the following: NIA(R01-AG-24296); OCAST(HR04-1138;AWG); and GCRC(M01-RR-14467).

Respostas cardiovasculares ao teste ergométrico em indivíduos com claudicação intermitente. DOI: 10.5007/1980-0037.2011v13n3p208

Studies suggest that patients with intermittent claudication (IC) present abnormal cardiovascular responses during treadmill exercise. However, it remains unclear whether this response is influenced by the severity of the disease. The objective of this study was to analyze the impact of IC severity on cardiovascular responses to an exercise test in subjects with peripheral arterial obstructive disease. Forty-seven men and women with IC, with a mean age of 65±9 years, participated in the study. The subjects underwent an exercise test on a treadmill using a specific protocol for this population. The subjects were divided into three groups according to the distance walked in the test: 1st tertile, walked from 210 to 420 m; 2nd tertile, walked from 450 to 700 m, and 3rd tertile, walked from 740 to 1060 m. Systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR) and rate-pressure product (RPP) were measured at rest, in the first stage of the treadmill test, and during peak exercise. SBP and DBP increased along the exercise test in the three tertiles. HR and RPP increased along the test in the three tertiles, and these increases were higher in the 1st tertile than in the other tertiles in the first stage. However, similar HR and RPP were observed for the three tertiles during peak exercise. In conclusion, the severity of IC did not affect blood pressure responses during treadmill exercise. However, HR and RPP were higher during submaximal exercise in subjects with more severe IC.