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| GHA 2010 HIGHLIGHTS |
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| Year : 2010 | Volume
: 11
| Issue : 2 | Page : 77-83 |
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GHA 2010 Highlights
| Date of Web Publication | 26-Nov-2010 |
Correspondence Address:
 Source of Support: None, Conflict of Interest: None  | Check |
How to cite this article:
. GHA 2010 Highlights. Heart Views 2010;11:77-83 |
Diastology for the clinician
Rick A. Nishimura
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
Introduction
In the past, cardiac function was looked upon as being similar to a 'pump'. In patients with heart failure, the underlying pathophysiology was associated with a decrease in systolic function of the heart. However, it is now evident that abnormalities of diastolic function play as great a role, if not greater, in producing the signs and symptoms of heart failure as systolic function. It is thus essential to understand the pathophysiology of diastolic filling of the heart the ability to measure these abnormalities. Treatment given to a patient with diastolic dysfunction will depend on an understanding of the etiology, pathophysiology, and measurements.
Pathophysiology
Diastole is a complex sequence of multiple inter-related events. These events include relaxation, suction, erectile coronary effects, viscoelastic forces of the myocardium, pericardial restraint, chamber stiffness, as well as many other factors. In the past, it was very difficult to understand these pathophysiological processes, much less measure them. Previous measurements required simultaneous analysis of continuous pressure and volume changes, which were impractical in clinical practice. However, it is now possible to look upon diastole in a more simplistic approach, using this foundation for measurement and treatment.
A Simplified Approach for Clinicians
One can look upon diastolic filling of the heart as consisting of several major parts. The first is ventricular relaxation, in which actin and myosin filaments disengage due to calcium reuptake into the sacroplasmic reticulum, rapidly lowering left ventricular pressure. When left ventricular pressure drops below left atrial pressure, the mitral valve opens and flow from the left atrium to the left ventricle occurs. Relaxation will continue during the early stages of filling, but the relationship of pressure and volume is determined by the effective operative compliance of the left ventricle. Finally, at end-diastole, there is an increase in the preload from atrial contraction. The transmitral Doppler reflects the relative diastolic pressure difference between the left atrium and the left ventricle, thus allowing determination of abnormalities of relaxation and ventricular filling noninvasively. In the early stages of the disease, abnormalities of relaxation occur, in which the rate of left ventricular pressure becomes slower. Then there is less blood flowing from left atrium to left ventricle in early diastole. This is compensated for by an increase in flow at end-diastole. This results in the transmitral flow velocity curve of 'abnormal relaxation', in which there is a low E-wave, high A-wave, and prolongation of deceleration time. As disease progresses, abnormalities of muscle stiffness and effective operative compliance become prominent. At this stage, there is a significant increase in left atrial pressure due to the abnormal pressure volume relationship. Thus, at the time of mitral valve, opening the high left atrial pressure will 'push' blood from left atrium to left ventricle resulting in early rapid filling. The transmitral flow velocity curve will then become a 'restriction to filling', in which there is a high E-velocity, low A-velocity, and short deceleration time. In patients with abnormal systolic function, the stage of diastolic dysfunction can be determined by examining the E:A ratio and deceleration time.
In patients with normal ejection fraction, ventricular suction must be taken into consideration. In normal patients with enhanced ventricular relaxation, there may be an increase in early filling of the left ventricle due to a more rapid rate of relaxation which 'sucks' the blood rapidly from left atrium to left ventricle, allowing the left ventricle to fill without elevating left atrial pressure. This is the mechanism by which stroke volume is able to increase during periods of stress and exercise. However, this results in a transmitral flow velocity curve, which is similar to that of 'restriction' to filling, with early rapid filling. Thus, in patients with normal systolic function, it is essential to be able to differentiate between excellent filling from 'suction' versus poor filling from 'enhanced driving force'. Evaluation of Doppler tissue velocities of the mitral annulus is helpful to differentiate between these states. In patients with enhanced relaxation, there will be an increase in velocity of the annulus, whereas, in patients with poor filling and abnormal relaxation, there will be a decrease in velocity. The tissue velocity is called e' velocity. Thus, a low mitral E/e' ratio (< 8) indicates excellent filling. An E/e' ratio that is high (> 15) indicates very poor filling.
Heart Failure with Normal Ejection Fraction
The most common presentation of patients with diastolic dysfunction is the elderly woman who presents with recurrent episodes of heart failure with a normal ejection fraction. This is termed 'HFpEF' (heart failure with preserved ejection fraction). The majority of these patients is an example of the 'dynamic nature of diastolic filling abnormalities'. These patients usually start out as having abnormal relaxation and compensated filling pressures. However, under stress of ischemia or an increase in afterload from hypertension, filling pressures markedly increase. Fortunately, this is all reversible. It is only at the end stages of disease, in which there are truly severe muscle stiffness abnormalities, will patients have severe diastolic dysfunction,thatis not responsive to treatment of abnormal loading conditions.
Treatment
In the majority of patients, the conventional treatment is to reduce the afterload and prolong diastolic filling. Beta blockers and calcium channel blockers are ideal drugs for this. There have been multiple studies which looked at the effect of blocking the renin angiotensin pathway, but no study has shown that either an angiotensin-converting enzyme inhibitor or an angiotensin II receptor blocker is effective in treating diastolic dysfunction. New areas of investigation include drugs that break the cross-links of the extracellular matrix, such as, ALT-711, ranolazine, and the PDE5A inhibitor, sildenafil. Further investigation is required to determine the ultimate utility of these medications.
Myocardium salvage and/or regeneration: The target of coronary intervention
Roberto Ferrari
Department of Cardiology, University of Ferrara and Salvatore Maugeri Foundation, IRCCS, Ferrara, Italy
Modern treatment of acute myocardial infarction is by reperfusion, either pharmacological (thrombolysis) or mechanical (primary angioplasty). The benefit of reperfusion, however, is time-dependent both in experimental models and in humans with a precise time-gradient for success depending on the experimental model considered: Seconds in myocytes, minutes in isolated hearts, hours in intact animals and in humans. The gradient in turn depends on the velocity by which myocytes develop necrosis.
Thrombolysis is more rapid and feasible than primary angioplasty, but has contraindications, is not always efficacious and has a higher risk of reocclusion. This is due to the fact that not all thrombi are the same and according to genetic factors, can be more or less resistant to thrombolysis. Primary angioplasty is more efficacious and has less contraindications than thrombolysis, but it has a procedural delay and requires high clinical competence and a sophisticated network.
An acute myocardial infarction can also trigger bone marrow production of stem cells, particularly the endothelial progenitor ones (EPC), with a peak between seven and ten days after myocardial infarction. Although the ultimate trigger for stem cell production and mobilization from the bone marrow is not known, it is likely that cytokines produced by necrosis are involved. Different growth factors or direct intracoronary EPC injections have been attempted to regenerate the necrotic myocytes or the consequent scarring. Results are still controversial, but this is a promising therapeutic avenue.
Electrocardiography of the paced patient
David L. Hayes
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
With the ever-increasing sophistication of permanent pacemakers, it is critical to have a systematic approach to assess the paced electrocardiogram. A systematic approach will allow a reliable differentiation between normal pacing, gross abnormalities on the paced electrocardiogram and situations where there may appear to be an abnormality, but it is actually a function of the programmed parameters and represents normal function.
It is critical to understand and be able to work through a differential diagnosis for failure to pace, failure to capture, under- and over-sensing, as well as a thorough understanding of the atrioventricular (AV) interval, and intricacies of crosstalk and safety pacing.
After working through the basic differentials of the most common pacing problems, if a concern still exists that pacing may be abnormal, one should focus on the nuances of the specific pulse generator. All manufacturers, and sometimes pulse generators from the same manufacturer, have programmable parameters or algorithms that may have specific operational characteristics, which would explain a finding on the paced electrocardiogram that may otherwise appear as an abnormality. If an adequate explanation cannot be found online or in the technical manual, the manufacturer should be contacted to help interpret the electrocardiogram.
Indications for pacing and defibrillation
David L. Hayes
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA
The indications for Cardiac Implantable Electronic Devices (CIEDs), including pacemakers, defibrillators, and Cardiac Resynchronization Therapy (CRT) devices are evaluated periodically by several of the professional societies. The most recent document from the American Heart Association / American College of Cardiology / Heart Rhythm Society was published in 2008. The most recent document from the European Society of Cardiology was published in 2007. For the most part, the documents are concordant in their recommendations.
The indications for pacing have largely been the same for many years, with slight changes occurring in the areas of neurocardiogenic syncope and pacing for hemodynamic improvement in specific cardiac disorders.
The indications for implantable cardioverter defibrillator (ICD) therapy have undergone some change with the marked growth of CRT. Consideration must be carefully given to whether the patient will benefit most from CRT-P or CRT-D therapies. In addition, given a growing body of literature regarding the potential adverse hemodynamic consequences of right ventricular apical pacing, one must consider whether pacemaker-dependent patients with left ventricular dysfunction, even if they are asymptomatic, should receive a CRT device.
Examining clinical scenarios where there is an overlap of device indications and guideline interpretation help clarify the approach to device selection.
Robotic beating heart coronary artery bypass surgery - How far are we from a clinical routine?
Jean-Luc Jansens
Cardiac Surgeon, Brussels, Belgium
Since the first attempts of less invasive coronary surgery more than two decades ago, many technical and technological developments have made this approach safer, more reproducible, and with similar clinical results as conventional coronary artery bypass graft (CABG). All those carry many benefits in terms of decreasing morbidity, preserving a stable chest cavity, fast time of recovery, and better aesthetic results. The venue of robotics in cardiac surgery less than 10 years ago was meant to change the paradigm of invasiveness, as this device theoretically allowed one to complete coronary anastomoses on the beating heart, and on the closed chest. This would have been a step forward for cardiac surgery, as in its willingness to offer an elegant coronary treatment, it would be able to compete not only with other minimally invasive surgical treatments, but also with invasive cardiology treatments. However, only a few surgical teams adopted this technology routinely because of its difficulty in terms of learning curve, teamwork spirit, and dramatic change in surgical philosophy. Moreover, at that time specifically designed tools for easing the coronary procedures were not user-friendly, leading to long procedural times. Recently, a new robotic device has been developed: the da Vinci S™ and Si™. The major advantage is the fourth arm, which is specially designed for stabilizing the heart while making the coronary suture. This step has been extremely important, as it has improved the safety and reproducibility of totally endoscopic coronary surgery. Moreover, it allows entering the field of coronary hybrid procedures, by having a real minimally invasive single LIMA-to-LAD bypass combined with stenting of the non-LAD lesions. Mixing both treatments, preferably during the same session in a hybrid suite, is probably an elegant - and cost-effective manner in which to treat coronary patients. It definitely requires a complete change in the cardiology environment, anda complete change of mind in terms of collaboratAt this point, hybrid revascularization requires large studies before being widely accepted, but it is certainly worth exploring this path.
Patent foramen ovale: A misty problem
J. Roelandt
Thoraxcentre, Erasmus University Medical Center, Rotterdam, The Netherlands
Patent Foramen Ovale (PFO), the remnant of an embryologic circulatory bypass, is present in approximately one-fourth to one-third of all adults. Most of the time, the PFO is kept closed by a positive L-to-R atrial pressure gradient, which holds the two septal membranes together. When Right Atrial (RA) pressure exceeds Left Atrial (LA) pressure, a R-to-L shunt flow through the PFO ensues. In some cases, dilatation of the atria or an abnormal redundancy of the septal membranes may result in a spontaneous L-to-R shunt, such as in atrial septal aneurysm. An atrial septal aneurysm is diagnosed if there is a fixed displacement or a mobile excursion of the fossa ovalis region of the atrial septum toward the RA or LA, or both, exceeding 10 mm.
The association of PFO and otherwise unexplained neurological ischemic insults has been intensively studied over the last decades after studies showed a significantly increased PFO incidence in younger patients, with unexplained stroke, but the causality has not been conclusively established and remains an area of clinical uncertainty and debate.
Paradoxical embolism through a PFO is a rare cause of a neurological ischemic insult except in the context of a rise in RA pressure (e.g., pulmonary embolism)Otherwise, caution must be exercised. In the absence of more likely causes of an unexplained stroke a PFO should be considered in younger patients (< 55 years old), in the presence of an atrial septal aneurysm together with a PFO, when there is a temporal relationship of the event with venous thrombosis, and when there is a large provokable R-to-L shunt. However, shunt quantification is difficult.
Transesophageal echocardiography complimented with echo contrast remains the standard diagnostic procedure, although newer equipment with harmonic imaging may reach equal sensitivity.
Real-time three-dimensional echocardiography in valve assessment
J. Roelandt
Thoraxcenter, Erasmus University Medical Centre, Rotterdam, The Netherlands
The diagnosis and management of heart valve disease has progressed rapidly over the past decade. The understanding of the etiology and natural history as well as the surgical and interventional management have all improved dramatically, mainly as a result of the non-invasive assessment by echocardiography and more particularly real-time three-dimensional echocardiography (RT3DE).
Recently, transesophageal RT3DE has become available. By providing high-quality images it is now considered the imaging technique of choice to decide on valve repair or replacement, for guiding percutaneous procedures, and the follow-up of these patients.
The performance of RT3DE is superior to 2DE for assessing valve morphology and function in:
- mitral stenosis (orifice area, indication and guiding for valvuloplasty)
- mitral prolapse (scallop definition, type of esions, e.g., chordal elongation or rupture)
- leaflet redundancy/distention, and annulus dilatation
- mitral regurgitation (morphological assessment, percutaneous or surgical repair?)
- aortic and right-sided valve disease (currently only morphological assessment)
Quantification of the severity of a valve lesion is essential for clinical decision-making, and RT3DE and echo-Doppler allow a comprehensive severity assessment by providing accurate hemodynamic, volume, and function measurements.
Increasing importance of left atrial size assessment
J. Roelandt, M.D.
Thoraxcentre, Erasmus University Medical Centre, Rotterdam, the Netherlands
Left Atrial (LA) enlargement is a strong predictor of Left Ventricular (LV) diastolic overload, morbidity, and mortality in the general population and in common cardiovascular conditions. Therefore, LA size assessment must be incorporated into the routine echocardiographic examination.
The LA is a volume sensor and its enlargement in patients without valvular disease represents the integration of LV diastolic performance over time, indicating LV diastolic dysfunction, regardless of the loading conditions at the time of the examination.
The LA anteroposterior dimension has been traditionally used in routine practice to assess its size, but it is unreliable. Therefore, volume measurements should be used (biplane Simpson's rule, area-length method, 3D echo) and indexed for body surface area.
There is considerable data indicating the relationship between LA enlargement and adverse cardiovascular outcomes in individuals without a history of atrial fibrillation or valvular disease, including: atrial fibrillation, stroke, myocardial infarction, heart failure, and mortality.
Percutaneous pulmonary valve implantation using the edwards sapien™ Thv
Ziyad M. Hijazi, MPH, FSCAI
Rush Center for Congenital and Structural Heart Disease at Rush University Medical Center, Chicago, IL USA
Significant pulmonary valve regurgitation results in progressive right ventricle dilation that may lead to the risk of development of ventricular arrhythmias, right ventricle dysfunction, and sudden death. The occurrence of pulmonary regurgitation and / or obstruction is not uncommon after surgery for congenital heart defects, including tetralogy of Fallot, pulmonary atresia, and any other surgical procedure requiring reconstruction of the right ventricle outflow tract.
Even if a valved conduit or a bioprosthetic valve has been used for this purpose, progressive pulmonary regurgitation and / or stenosis of such conduits or valves (homografts, Contegra, porcine valves) can occur. Surgical pulmonary valve implantation at an appropriate age may restore right ventricular function and improve the symptoms, however, cardiopulmonary bypass and ventriculotomy needed for such operations may further impair right ventricular function. Therefore, timing and indications for resurrection of a competent pulmonary valve are still controversial issues.
Bonhoeffer was the first one to implant a percutaneous valve in the pulmonic position, using a bovine jugular vein with a valve mounted inside a stent. Since then, Cribier and his colleagues reported on the first human application of another Percutaneous Heart Valve (PHV) in the aortic position. This valve was designed initially for application only in the aortic position, and the early clinical experience with this PHV in the aortic position is ongoing.
We have tested the same valve on the right side of the cardiac circulation. The testing involved acute and chronic animal studies, which demonstrated that the valve could perform well in the pulmonic position.
In December 2005, we implanted this valve in a 16-year-old patient, who had a failed conduit between the right ventricle and pulmonary artery. Since then, a clinical trial (COMPASSION) sponsored by the United States FDA has been underway and to date, 26 patients have been enrolled. Their ages range from 11 to 71 years, with weight > 35 kg in all. I will discuss the results of the US clinical trial that is in process at the time.
Management of coarctation of the aorta
Ziyad M. Hijazi
Rush Center for Congenital and Structural Heart Disease at Rush University Medical Center, Chicago, IL, USA
Coarctation of the aorta is typically a discrete narrowing of the thoracic aorta just distal to the left subclavian artery. The care of a patient with coarctation depends upon the severity of the coarctation, patient age, and clinical presentation.
The treatment plan for patients with coarctation of the aorta depends upon patient age, presentation, and morphology.
Infants with heart failure need immediate and aggressive medical treatment for stabilization prior to surgery. Medical therapy consists of continuous intravenous infusion of prostaglandin E1 to keep the ductus arteriosus open, dopamine and / or dobutamine, in addition to correction of metabolic acidosis, hypoglycemia, and anemia.
The standard approach is to proceed with surgical repair after the patient has been stabilized. Since the introduction of prostaglandin E1, it is rare for a neonate to require emergency surgical repair because of inability to achieve stability, and balloon angioplasty is rarely performed as a palliative emergency procedure.
Indications for intervention include hypertension, heart failure, peak instantaneous pressure gradient across the coarctation of more than 20 mmHg, by Doppler, or catheterization, and / or collateral circulation on Magnetic Resonance Imaging (MRI). The resting gradient alone may be an unreliable indicator of severity when there is significant collateral circulation.
Correction of coarctation should be performed in early childhood to prevent the development of systemic hypertension. If coarctation escapes early detection, repair should be performed at the time of subsequent diagnosis.
Various catheter interventional techniques will be discussed in detail, including balloon angioplasty and stent implantation. Stent implantation is emerging as the therapy of choice in children / adolescent and adults with coarctation. Any catheter laboratory involved in treating coarctation should be equipped with a covered stent to manage complications.
Pregnancy and heart disease
Carole A. Warnes
Division of Cardiovascular Diseases, Mayo Clinic Rochester, MN, USA
Two percent of pregnancies involve maternal cardiovascular (CV) disease. Most women with CV disease can have a pregnancy with proper care, but there is increased risk to mother and fetus and prepregnancy counseling is mandatory.
Plasma volume increases by approximately 50%. Peripheral resistance falls, and so stenotic lesions are not as well-tolerated as regurgitant lesions. A prepregnancy evaluation including clinical examination, echocardiogram, and an exercise test is imperative at a center where there is expertise. Maternal and fetal risks should be discussed. During pregnancy, labor, and delivery, a multidisciplinary approach should be adopted where the obstetrician, cardiologist, and anesthesiologist work together.
High-risk lesions include:
- Pulmonary hypertension
- Symptomatic obstructive lesions: Aortic stenosis, Pulmonic stenosis, and coarctation
- EF < 40%
- History peripartum cardiomyopathy
- Marfan syndrome and aortopathies with aortic root > 40 mm
Eisenmenger syndrome: Maternal mortality is approximately 30%, even in the current era.
Stenotic lesions: Aortic stenosis: Pregnancy can sometimes be prolonged if patients are put on bed rest, and an early delivery may be necessary. Balloon valvotomy can be performed, provided valve anatomy is appropriate. Rarely, valve replacement may be necessary during pregnancy.
Peripartum cardiomyopathy: Some women may normalize their LVEF, although, approximately 20% will get heart failure symptoms with a subsequent pregnancy. Reduction of EF may again be noted, sometimes permanently. Because of the 30% likelihood of peripartum cardiomyopathy occurring again, it is usually advisable to avoid a pregnancy.
Initial evaluation and treatment of pulmonary hypertension
Carole A. Warnes, M.D. F.R.C.P., F.A.C.C.
Division of Cardiovascular Diseases, Mayo Clinic Rochester, MN, USA
Definition: Mean pulmonary artery pressure (PAP) > 25 mmHg; pulmonary capillary wedge pressure (PCW), left atrial pressure (LAP) or left ventricular end diastolic pressure (LVEDP) < 15 mmHg; pulmonary arteriolar resistance > 3 Wood units.
Major categories include:
- Pulmonary arterial hypertension (PAH)
- Pulmonary hypertension (PH) with left heart disease
- PH associated with lung disease and / or hypoxemia
- PH due to chronic thrombotic or embolic disease
- Miscellaneous
The diagnostic evaluation should include a comprehensive evaluation including: echocardiography, pulmonary function tests, connective tissue serology, cardiac catheterization, and tests to exclude thromboembolic disease.
Connective tissue disease may be associated with PH. This is most common and severe in patients with CREST, and at autopsy, up to 80% have pulmonary arterial hypertension (PAH). Congenital heart disease should be ruled out (atrial septal defect (ASD), ventricular septal defect (VSD), patent ductus artery (PDA)). Those with Eisenmenger syndrome have a better survival than those with idiopathic pulmonary arterial hypertension (IPAH).
Portal hypertension may also cause PAH due to an imbalance in vasoactive substances due to the liver disease.
PH due to left heart disease should be ruled out by echocardiography.
Chronic Pulmonary Emboli (PE) may also cause PAH, and 3 to 4% of patients with acute PE develop thromboembolic pulmonary hypertension (CTEPH). Conversely, 50% of patients with CTEPH have no history of acute PE. The appropriate screening test is a V/Q scan, as normal or very low probability essentially excludes CTEPH.
The six-minute walk distance is strongly predictive of survival: < 332 meters, there is a 20% three-year survival, > 332 meters, there is a 92% three-year survival.
Cardiac catheterization and vasodilator testing should be performed, as responsiveness identifies patients with a better prognosis.
Common problems in the adult with congenital heart disease
Carole A. Warnes, M.D. F.R.C.P., F.A.C.C.
Division of Cardiovascular Diseases, Mayo Clinic Rochester, MN, USA
Coarctation of the Aorta: Surgical repair of coarctation is often mistakenly considered as 'curative.' Thirty-year survival is 72% and mean age at death is 38 years. Causes of death include coronary artery disease, sudden death, heart failure, stroke, and ruptured aortic aneurysm. The aorta is abnormal in its entirety with a diffuse aortopathy associated with medial changes. Thus, patients are at risk of dissection, rupture, and aneurysm at the site of coarctation repair. Multimodality imaging of the entire aorta is necessary throughout life. Meticulous control of blood pressure both at rest and exercise should be accomplished. Patients should be screened for coronary artery disease and risk factors optimized. Patients have a five-fold increase in intracranial aneurysms.
Tetralogy of Fallot :Tetralogy of Fallot repair was first performed in 1954. Adults frequently present with atrial arrhythmias: If this occurs, an underlying hemodynamic abnormality should be sought. The most common problem is pulmonary regurgitation. Pulmonary valve replacement should be accomplished before there is irreversible right ventricle (RV) dysfunction, which is associated with an increased propensity for ventricular tachycardia and sudden death.
Congenitally Corrected Transposition : In this anomaly, the right ventricle functions as the systemic ventricle. The tricuspid valve (the systemic AV valve) is frequently regurgitant. This should be replaced before there is irreversible systemic (RV) dysfunction. Commonly, patients are referred late with advanced heart failure, and even though surgery can be accomplished successfully in experienced centers, there is an increased risk of death or the need of cardiac transplantation in the subsequent decade.
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