Ignite Creation Date:
2024-05-05 @ 11:32 AM
Last Modification Date:
2024-10-26 @ 9:09 AM
Study NCT ID:
NCT00074880
Status:
COMPLETED
Last Update Posted:
2008-03-04
First Post:
2003-12-22
Brief Title:
The Role of Heart Stiff and Weak Atrium on Exercise Capacity in Patients With Hypertrophic Cardiomyopathy
Sponsor:
National Heart Lung and Blood Institute NHLBI
Organization:
National Institutes of Health Clinical Center CC
Study Overview
Official Title:
The Role of Atrio-Ventricular Coupling in Exercise Tolerance in Non-Obstructive Hypertrophic Cardiomyopathy
Status:
COMPLETED
Status Verified Date:
2005-03
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
This study will examine how heart stiffness and a weak atrium affect exercise capacity and symptoms in patients with hypertrophic cardiomyopathy HCM The atrium is the booster pumping chamber of the heart that helps the ventricle main pumping chamber to fill properly HCM is an inherited disease in which the ventricle becomes thickened and in some patients stiff The stiffness makes it difficult for the ventricle to fill and empty causing breathing difficulty fatigue and reduced exercise capacity Scar formation and a weakened atrium can cause the heart to stiffen Information gained from this study may guide doctors in prescribing medicines to reduce scarring or improve atrial function
Patients 21 years of age and older with hypertrophic cardiomyopathy may be eligible for this study Candidates will be screened with a medical history and physical examination electrocardiogram EKG blood tests Holter monitor and echocardiogram A Holter monitor is a device about the size of a Walkman that is connected to three wires that are attached to the chest It is worn for 24 hours to provide continuous monitoring of heart rhythm An echocardiogram uses a small probe that emits sound waves to produce images of the heart The probe is moved across the chest and the reflection of the sound waves from the chambers of the heart produce images showing the hearts thickness and function
Participants will undergo the following tests and procedures over 3 days
Physical examination and echocardiogram
Intravenous cannula insertion A plastic tube is inserted into an arm vein for collecting blood samples to measure substances that the heart and circulatory system release at rest and during exercise
Impedance cardiography A small current of electricity is passed across the chest and electrodes similar to those used for an EKG test are placed to measure blood flow in the area of the current
Pulmonary artery catheterization A catheter plastic tube is inserted into a vein either in the arm under the collarbone or in the neck and advanced to the right atrium and ventricle The catheter remains in place during the echocardiogram tilt and bicycle exercise tests see below
Echocardiogram tilt test The patient lies flat on a table After a few minutes the table is tilted so that the patients head is just above his or her feet for a short while then is positioned flat again and then tilted so the feet are just above the head Echocardiographic measurements and blood samples are taken at intervals to examine heart function during changes in posture
Echocardiogram bicycle stress test The patient exercises for as long as possible on a bicycle-like machine while lying on his or her back Echocardiographic measurements and blood samples are taken at intervals during the test
Treadmill stress test The patient runs for as long as possible on a treadmill that increases in difficulty The patient wears a facemask or mouthpiece through which small amounts of gases are added in order to measure the ability of the heart and lung to increase their effectiveness with exercise
Digoxin loading Only patients who demonstrate limited exercise capacity and for whom digoxin is not a risk will undergo this procedure A medicine that makes the heart contract more strongly digoxin is used to treat certain heart abnormalities Patients are given doses of either digoxin or placebo a look-alike injection with no active ingredient at 4-hour intervals over a 24-hour period and then repeat the tilt test and the bicycle and treadmill exercise tests
Patients 21 years of age and older with hypertrophic cardiomyopathy may be eligible for this study Candidates will be screened with a medical history and physical examination electrocardiogram EKG blood tests Holter monitor and echocardiogram A Holter monitor is a device about the size of a Walkman that is connected to three wires that are attached to the chest It is worn for 24 hours to provide continuous monitoring of heart rhythm An echocardiogram uses a small probe that emits sound waves to produce images of the heart The probe is moved across the chest and the reflection of the sound waves from the chambers of the heart produce images showing the hearts thickness and function
Participants will undergo the following tests and procedures over 3 days
Physical examination and echocardiogram
Intravenous cannula insertion A plastic tube is inserted into an arm vein for collecting blood samples to measure substances that the heart and circulatory system release at rest and during exercise
Impedance cardiography A small current of electricity is passed across the chest and electrodes similar to those used for an EKG test are placed to measure blood flow in the area of the current
Pulmonary artery catheterization A catheter plastic tube is inserted into a vein either in the arm under the collarbone or in the neck and advanced to the right atrium and ventricle The catheter remains in place during the echocardiogram tilt and bicycle exercise tests see below
Echocardiogram tilt test The patient lies flat on a table After a few minutes the table is tilted so that the patients head is just above his or her feet for a short while then is positioned flat again and then tilted so the feet are just above the head Echocardiographic measurements and blood samples are taken at intervals to examine heart function during changes in posture
Echocardiogram bicycle stress test The patient exercises for as long as possible on a bicycle-like machine while lying on his or her back Echocardiographic measurements and blood samples are taken at intervals during the test
Treadmill stress test The patient runs for as long as possible on a treadmill that increases in difficulty The patient wears a facemask or mouthpiece through which small amounts of gases are added in order to measure the ability of the heart and lung to increase their effectiveness with exercise
Digoxin loading Only patients who demonstrate limited exercise capacity and for whom digoxin is not a risk will undergo this procedure A medicine that makes the heart contract more strongly digoxin is used to treat certain heart abnormalities Patients are given doses of either digoxin or placebo a look-alike injection with no active ingredient at 4-hour intervals over a 24-hour period and then repeat the tilt test and the bicycle and treadmill exercise tests
Detailed Description:
Primary hypertrophic cardiomyopathy HCM is a genetic cardiac disease characterized by thickening hypertrophy of the left ventricular LV wall dyspnea andor fatigue in the setting of a normal or supra-normal LV ejection fraction The specific mechanisms underlying heart failure-related symptomatology in non-obstructive HCM are poorly defined but as the vast majority of HCM patients with heart failure have apparently preserved LV contractile function their symptoms of dyspnea and fatigue are presumed due to perturbations of the relaxationfilling phase diastole of the cardiac cycle which has been termed diastolic dysfunction In fact diastole is mechanistically complex and involves LV pressure decay relaxation chamber compliance and atrial contractile function LV end-diastolic volume which represents fiber stretch governs LV contractile function and stroke volume via the Frank-Starling mechanism End-diastolic fiber stretch is in turn dependent on late diastolic filling due to atrial ejection This atrial booster pump is load-dependent and also responsive to inotropic effect The interaction of atrial inotropic reserve LV end-diastolic pressure atrial afterload and LV compliance which mediates LV end-diastolic pressure and volume may be generically considered as atrio-ventricular coupling which in theory should be at least partially responsible for modulations in exercise-induced augmentation of cardiac output related to enhancement of LV end-diastolic volume or preload reserve Previous studies have suggested that limitations of preload reserve may explain exercise-associated symptoms of congestive heart failure The potential ability of new technologies to accurately assess atrio-ventricular coupling as it relates to preload reserve present opportunities for investigation into mechanisms of heart failure operative in patients with stiff left ventricles with intact systolic function Elucidation of these previously unapproachable mechanisms may be important in targeting therapy and the design and analysis of future interventional trials
In this pilot study we hypothesize that exercise intolerance in HCM patients is due to limited LV preload-reserve which in turn is mediated by disequilibrium of atrio-ventricular coupling and possibly limitations in atrial inotropic reserve We will test novel analytic tools including measures of LV compliance and load-independent atrial systolic fuction atrial systolic elastance in attempts to dissect out the components of atrio-ventricular coupling which underly HCM-associated symptoms and reduced preload reserve Further we will assess serum and cardiac MRI markers of myocardial fibrosis to determine the effect of collagen remodeling on LV relaxation compliance and atrial afterload Finally we will examine the effects of short-term cardiac glycoside inotropic therapy on atrial systolic elastance preload reserve and exercise tolerance The results of this investigation will be implemented in the design of subsequent interventional protocols targeted towards mechanisms of the stiff heart syndrome
In this pilot study we hypothesize that exercise intolerance in HCM patients is due to limited LV preload-reserve which in turn is mediated by disequilibrium of atrio-ventricular coupling and possibly limitations in atrial inotropic reserve We will test novel analytic tools including measures of LV compliance and load-independent atrial systolic fuction atrial systolic elastance in attempts to dissect out the components of atrio-ventricular coupling which underly HCM-associated symptoms and reduced preload reserve Further we will assess serum and cardiac MRI markers of myocardial fibrosis to determine the effect of collagen remodeling on LV relaxation compliance and atrial afterload Finally we will examine the effects of short-term cardiac glycoside inotropic therapy on atrial systolic elastance preload reserve and exercise tolerance The results of this investigation will be implemented in the design of subsequent interventional protocols targeted towards mechanisms of the stiff heart syndrome
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None
Secondary IDs
| Secondary ID | Type | Domain | Link |
|---|---|---|---|
| 04-H-0062 | None | None | None |