Cardiac Failure at Young age- A Review

 

Krittika Ravi1, Dhanraj Ganapathy2, Sherlyn Sheeba3

1Graduate Student, Saveetha Dental College, Saveetha University, Chennai.

2Professor and Head of the Department of Prosthodontics, Saveetha Dental College, Saveetha University, Chennai.

3Tutor, Department of General Anatomy, Saveetha Dental College, Saveetha University, Chennai.

*Corresponding Author E-mail: dhanrajmganapathy@yahoo.co.in

 

ABSTRACT:

Cardiac failure is a complex pathophysiological disease that can occur in children due to variety of diseases, including cardiomyopathies, myocarditis, and congenital heart disease. Cardiac failure in children differs from adults in various aspects. The cause and clinical features of cardiac failure in children may differ considerably among children of different age category and between children and adults. The time of onset of cardiac failure plays the major role in diagnosis of the etiology. The overall result of cardiac failure in children is much better than in adults because of the structural heart diseases and reversible conditions. There is an ongoing investigation to enhance outcomes in high-risk populations, such as small infants and those with complex congenital heart disease. Although cardiac failure in adults has been the topic of extensive research and generation of evidencebased guidelines, there’s a deficiency of evidence base in pediatric cardiac failure.

 

KEYWORDS: Cardiac failure, congenital heart disorder,heart failure, young age.

 

 


INTRODUCTION:

Heart failure (HF) has been defined as an abnormality of cardiac structure or function leading to failure of the heart to deliver oxygen at a rate commensurate with the requirements of the metabolizing tissues, despite normal filling pressures (or only at the expense of increased filling pressures)[1]

 

Heart failure is a huge clinical burden in adults, to a great extent on account of the prevalence of atheromatous coronary disease. In youngsters, where coronary disease isn't the main source of heart failure, it is less normal. It is, however, a critical infection, representing 10% of pediatric heart transplants in youngsters.

 

 

 

Hsu and Pearson have given a good working definition of HF in children as a progressive clinical and pathophysiological syndrome caused by cardiovascular and noncardiovascular abnormalities that result in characteristic signs and symptoms including edema, respiratory distress, growth failure, and exercise intolerance, and accompanied by circulatory, neurohormonal, and molecular derangements[2].

 

Cardiac symptoms in youngsters are typically the result of congenital lesions. A large portion of these lesions, for example, septal defects, are agreeable to surgical intervention. It isn't suitable to develop the management of congenital heart lesions in this review. There is a little subgroup of children that have diastolic failure from cardiomyopathy restriction to flow.

 

The rest of the patients, which will be focused on below, have heart failure that is primarily related with poor myocardial function and to a great extent involve those children with dilated poorly contracting ventricles, which can be related with particular aetiologies in some cases. Specific topics of debate in pediatric cardiac failure concern:

1.     The diagnosis and management of myocarditis versus dilated cardiomyopathy

2.     The most suitable investigations for new onset cardiac failure

3.     Cell reactions to cardiac failure

4.     The increasing population of anthracycline treated survivors of childhood malignant disease treatment procedures.

 

EPIDEMIOLOGY:

In children, the causes of HF are significantly different from adults and many cases are due to congenital malformations which usually result in high output cardiac failure. Some children suffer from low output cardiac failure such as cardiomyopathy. Congenital Heart Disease [CHD] occurs in around 8/1000 live births. HF associated with CHD occurs in approximately 20% of all patients.

 

A significant number of the children with CHD get early surgical intercession and it has been evaluated that the yearly frequency of HF because of congenital defects is in between 1 and 2 for each 1000 live births[3]. The result of HF associated with CHD has changed drastically following the introduction of early surgical mediations. The frequency of symptomatic HF has additionally declined in the "early surgical period." Massin et al. reported that 10% of their patients in a tertiary care pediatric cardiology care setting created symptomatic HF[4].

 

Cardiomyopathy additionally contributes significantly to the number of pediatric patients who are seen with the side effects of cardiovascular failure. Rossano et al. from the United States report that 10,000–14,000 children are hospitalized each year with HF as one of their diagnosis and of those roughly 27% (around 3000) have abnormalities of the heart muscle as a fundamental cause[5]. The frequency of cardiomyopathies in developed nations is around 0.8– 1.3 cases for every 100,000 children in the 0– 18 years age category yet is ten times higher in the 0-to 1-year age group [6,7]. 90% of all cardiomyopathies in youngsters are of the dilated variety.

 

In contrast to HF secondary to CHD, the result of children with cardiomyopathy remains poor, with a 5-year risk for death or cardiac transplantation of around 50% for patients with dilated cardiomyopathy (DCM)[8].

 

Another significant group of diseases causing HF in young age in developing countries is rheumatic fever and rheumatic heart disease. While the rate and predominance of rheumatic fever and chronic rheumatic heart disease are well documented, there are insufficient data on presentation with HF in this group. A significant number of acute rheumatic carditis and established juvenile mitral stenosis present with features of HF[9].

 

CAUSES OF CARDIAC FAILURE:

For a child to develop and grow, the heart needs to maintain normal pumping function, to give ideal blood flow all through the body. However, once in a while the heart of a child may not work normally. The expression "heart failure" describes a heart that is not working normally. It doesn't imply that the heart has stopped working, but that it isn't functioning as good as it should. Heart failure happens in adults because of the impacts of smoking, hypertension, diabetes, coronary artery disease and bad heart valves. It can likewise happen in newborns, infants, toddlers and young children for different reasons. Since heart failure has diverse causes and outcomes, it's important to perceive how it's diagnosed, treated and even cured in young children.

                                                                             

There are two essential causes for cardiac failure in children and teenagers. The one to begin with. is known as, “over circulation failure”, occurs when blood mixes inside the heart because of a congenital heart defect. The second, known as “pump disappointment”, happens when the heart muscle gets damaged and never again contracts normally.

 

1. OVER CIRCULATION FAILURE:

Around 1 percent of every newborn baby will have some sort of basic heart defect. In some of these deformities, there are holes between the right and left chambers inside the heart. Due of these gaps, the blue and red bloods mix inside the heart. An imperfection of blood vessels in the head or different parts of the body (AV malformation) can cause comparable mixing of the blue and red blood however outside the heart. Abnormal heart valves can likewise cause cardiac failure. An unusually framed valve that does not close properly results in backward leakage of blood. Rarely, a Strep throat infection can bring about harm to otherwise normal heart valves, making them leak as well. But finally, low blood (anaemia) can likewise bring about cardiac failure. These defects leads to overcirculation failure. In each instance, an over-load blood flow design happens in at least one of the segments of the heart. The normal forward blood flow is hindered and the heart turns into an inefficient pump [10].

 

2. PUMP FAILURE:

As in the adults, a child's heart may have pump failure. This can be caused by an infection that harms otherwise typical heart muscle or from issues with the coronary arteries that happen from birth or are the consequence of the infection and prevent the effective blood flow to the heart muscle itself. Older children and adolescents may keep complaining about getting tired easily, particularly if a viral infection has caused heart muscle damage. Certain medications, some necessary medicines to treat other medical issues (like malignancy or leukemia) can likewise cause damage of the heart muscle. The heart's electrical framework likewise might be abnormal from birth or harmed by infection, making the heart beat too slow or too quick. In some cases, one of the heart valves does not open appropriately causing pressure to back up inside the heart chambers. Sometimes, extreme chest injury may harm the heart. Children with muscular dystrophy may in the end additionally create issues with their heart muscle. In all of these circumstances, the heart muscle fails to work normally and the heart turns into an inefficient pump[10].

 

DIAGNOSIS OF HEART FAILURE IN CHILDREN

HISTORY AND EXAMINATION:

The time of onset of CHF holds the way to the etiological determination of diagnosis. Reasons for HF in the fetus includes supraventricular tachycardia, bradycardia because of complete heart block, extreme tricuspid regurgitation because of Ebstein's anomaly of the tricuspid valve, mitral regurgitation from atrioventricular canal defect, systemic arteriovenous stula, myocarditis, and so on., HF presenting on the first day of life are usually because of metabolic anomalies, for example, hypoglycemia, hypocalcemia, asphyxia, or sepsis.

 

Structural diseases that create fetal cardiovascular failure can show on the first day. Conditions which show in the first seven day stretch of life includes critical obstructive lesions, such as extreme aortic stenosis, coarctation of the aorta (COA), obstructed total anomalous pulmonary venous connection (TAPVC), the great arteries (TGA) with intact ventricular septum (IVS), and hypoplastic left heart disorder.

 

Development of HF because of left-to right-shunts normally happens with the fall in pulmonary vascular resistance at 4– 6 weeks, however large ventricular septal imperfection (VSD), patent ductus arteriosus (PDA), atrio-VSD and aortopulmonary window can cause HF in the second seven day stretch of life. Different conditions such as truncus arteriosus, unobstructed TAPVC likewise show in the second seven day stretch of life. As premature newborn children have a poor myocardial hold and their pulmonary vascular resistance falls quicker PDA may bring about HF in the first week in them.

 

DCM is likewise a common reason for HF in infants. Reasons for DCM in infancy include idiopathic, inborn errors of metabolism, and malformation disorders. Older children (typically past 2 years) are probably going to have different reasons for HF like acute rheumatic fever with carditis, decompensated chronic rheumatic heart disease, myocarditis, cardiomyopathies, rhythm disturbances, and palliated CHD.

 

Clinical features suggestive of HF in newborn children include tachypnea, feeding trouble, diaphoresis, and so on., Feeding trouble ranges from prolonged feeding time (>20 min) with less volume intake to frank intolerance and the infant might vomit after feeding. Irritability with nourishing, sweating, and even refusal of feeds is additionally common.

                                                                                                                     

Established HF presents with poor weight gain and in the longer term, failure in linear development can likewise come about. Edema of face and limbs is very rare in newborns and young children. The clinical features of HF in an infant can be genuinely nonspecific and a high index of doubt is required. Tachycardia > 150/min, respiratory rate >50/min, gallop rhythm, and hepatomegaly are highlights of HF in newborn children. Primary cardiovascular arrhythmia has to be considered if heart rate is more than 220/min. Duct dependent pulmonary circulation seen with severe cyanosis and acidosis, whereas duct dependent systemic circulation seen with HF and shock.

 

Features of HF in older children and teenagers include fatigue, effort intolerance, dyspnea, orthopnea, abdominal pain, dependent edema, ascites, etc.

 

Unequal upper and lower limb pulses, peripheral bruits, or raised/asymmetric blood pressure demonstrating aortic obstructing have to be searched always for a child with unexplained HF at any age. COA in neonates can have typical femoral pulsations within the sight of PDA. COA for the most part does not cause HF following 1 year of age, when adequate collaterals have been developed. Central cyanosis, regardless of the possibility that can be mild, related with HF and soft or no murmurs in an infant suggests TGA with intact IVS, obstructed TAPVC, and etc.

 

An atrial septal deformity or VSD does not lead to CHF in the first 2 weeks of life and subsequently an extra reason like TAPVC or COA have to be found. Older children with tetralogy of Fallot physiology can develop HF because of difficulties, such as anaemia, infective endocarditis, aortic regurgitation, or overshunting from aortopulmonary shunts.

 

New York Heart Association (NYHA) HF classification isn't pertinent to the greater part of the pediatric populace. The Ross HF classification was created to evaluate seriousness in newborn children and has accordingly been modified to apply to every single pediatric age. The modified Ross classification for children gives a numeric score practically identical with the NYHA classification for adults.

 

INVESTIGATIONS:

Basic investigations such as chest radiography (CXR), electrocardiography (ECG), and echocardiography are indicated in all patients with suspected HF.

 

Imaging studies are basic to influencing the diagnosis of cardiac failure. Chest X-rays are valuable for the determination of cardiomegaly and pulmonary edema, however particular cardiovascular imaging with echocardiogram and additionally heart MRI is required. For most types of cardiomyopathy, the ventricular capacity will be discouraged, however patients with restrictive or hypertrophic cardiomyopathy can have heart failure with preserved ventricular function. While echocardiogram remains the most commonly used cardiovascular imaging modality, heart MRI is progressively getting to be used. Additionally, the demonstration of structural abnormalities, ventricular size, and ventricular function, evaluations of myocardial inflammation and myocardial scar/fibrosis can be performed [11]. These assessments can be helpful in deciding the etiology of heart muscle illness. Moreover, certain discoveries, such as diffuse fibrosis as confirmed by T1 mapping, may offer some prognostic information [12]. Genetic testing and counseling has likewise turned out to be progressively important in the diagnosis and treatment of patients with cardiomyopathy [13].

 

TREATMENT:

The principles of management include treatment of the cause, correction of any precipitating event, and treatment of systemic or pulmonary congestion. Wherever possible, the cause of CHF should be identified and treated.

 

In large left to right shunts, initial medical therapy is performed which is followed by prompt surgical therapy. Other conditions requiring prompt surgery or catheter intervention include severe AS or COA, TGA with IVS, obstructed TAPVC, etc.

 

The precipitating events such as intercurrent infections, anaemia, electrolyte imbalances, arrhythmia, infective endocarditis, drug toxicity, drug interactions, etc., have to be identified prior and corrected if any of the above present. Acute HF patients can also be present with symptoms related to fluid overload, under perfusion, or both at times. The early management of children with HF should address these problems and correct them.

 

In neonates, several causes of HF can present with acute circulatory collapse or progress to shock if not recognized early. Many of these conditions require maintenance of duct patency with prostaglandin infusion or emergency procedures such as ductal stenting and balloon atrial septostomy. Indiscriminate administration of intravenous fluid resuscitation is contraindicated and will worsen the condition of children with HF. In acute decompensation, general measures such as bed rest, propped up position, humidified oxygen sodium, and if required, volume restriction are followed routinely. Infants with CHF require 120–150 Kcal/kg/day of caloric intake and 2–3 mEq/kg/day of sodium[14].

 

PHARMACOLOGICAL THERAPY:

Medication treatment is given for lessening the pulmonary or systemic congestion by the usage of diuretics, increasing the contractility by inotropes, and decreasing the excessively raised afterload by vasodilators and by different measures. Routinely used medications in the management of heart failure in kids include diuretics, digoxin, angiotensin-converting enzyme inhibitors (ACEIs), spironolactone, beta-blockers, and inotropes. The medications which are still investigational include natriuretic peptides, vasopressin antagonists, renin inhibitors, endothelin antagonists, oral phosphodiesterase inhibitors, nitric oxide agonists, and neuropeptidase antagonists, and so on.

 

·       Diuretics: Frusemide is given intravenously at a dose of 1–2 mg/kg or 1–2 mg/h infusion. For chronic use 1–4 mg/kg of frusemide or 20–40 mg/kg of chlorothiazide in divided doses are used.

·       Digoxin: In most circumstances, starting with an oral maintenance dose (8–10 g/kg/day) with no loading dose is adequate. Dose reduction is required in HF patients on carvedilol and amiodarone targeting lower serum digoxin concentrations (e.g., 0.5–0.9 ng/ml) [15].

·       ACEIs: In children with cardiac failure, the ACEIs which have been most studied are captopril and enalapril [16,17]. Clinical improvement is demonstrated with these agents in left to right shunts with HF as well [18,19]. Captopril is preferred in neonates (0.4–1.6 mg/kg/day in 3 divided doses) and infants (0.5–4 mg/kg/day in three divided doses). Enalapril is the rst choice for those older than 2 years of age (0.1–0.5 mg/kg/day in two divided doses).

·       Spironolactone: Spironolactone is used most often in children because experience with eplerenone in children is limited. Usual starting dose of spironolactone is 1 mg/kg/day and the target maximum dose is 2 mg/kg/day.

·       Beta-blockers: In children with HF and related conditions, carvedilol has been the most widely studied beta-blocker. Carvedilol is started at 0.05 mg/kg/dose (twice daily) and increased to 0.4–0.5 mg/kg/dose (twice daily) by doubling the dose every 2 weeks. In many small scale and retrospective studies, carvedilol was found to be effective in improving clinical and echocardiographic parameters and preventing transplantation [20,21]

·       Inotropes: Milrinone, a phosphodiesterase inhibitor is an inotrope and vasodilator that has been shown to prevent low cardiac output syndrome after cardiac surgery in infants and children. [22] The loading dose of milrinone is 25–50 mcg/kg/min and maintenance dose is 0.25–1 mcg/kg/min.

 

DEVICE THERAPY:

Device therapy in HF majorly includes pacemaker therapy, cardiac resynchronization therapy (CRT), and mechanical circulatory support. In advanced second or third- degree atrioventricular block which is associated with ventricular dysfunction, the device therapy indicated for this is will be permanent pacemaker implantation. When a patient gives history of cardiac arrest or symptomatic sustained ventricular tachycardia with association of CHD, the indicated device therapy would be implantable cardioverter debrillator (ICD)[23].

ICD is sensible for patients with CHD with repetitive syncope within the presence of ventricular dysfunction or inducible ventricular arrhythmia at electro physiological study. CRT can be helpful for pediatric patients with a systemic LV with an EF < 35%, complete left bundle branch block pattern, QRS duration more than the upper limit of normal for age, NYHA Class II-IV on guideline- directed medicinal therapy [24].

Extracorporeal membrane oxygenation (ECMO) has been broadly utilized as a part of the setting of cardiopulmonary arrest. When a child presents with isolated cardiac failure which is trusted to be reversible, ECMO or a ventricular assist device (VAD) might be used as a temporizing measure as a bridge to recovery of function. ECMO is additionally used as an emergency perioperative salvage. Children with fulminant myocarditis with a high chance of recovery, they show good response and do well when ECMO and VADs are administrated [25,26]. Patients who require long- term mechanical support to bridge to cardiac transplantation, VADs are being used with increasing frequency. This type of devices offer univentricular or biventricular circuit support also which is of good use.

 

CARDIAC TRANSPLANTATION:

Cardiac transplantation will always be the therapy of choice for end- stage HF in children regardless to surgical and medical therapy. There were 9,566 pediatric heart transplants reported to the international society for heart and lung transplantation from 1982 to 2009[27]. The end –stage cardiac disease due to cardiomyopathies were the most common indication reported.

 

Other causes include CHDs such as hypoplastic heart syndrome and other complex CHD, single ventricle, and palliated heart disease. The data show an improved early (1 year) survival for all age groups in the more recent era of transplantation, averaging 80% in children and 90% in infants. The major complications in children are systemic viral infections such as cytomegalovirus, Epstein–Barr virus, and adenovirus, acute cellular rejection, allograft vasculopathy with graft failure, renal dysfunction, hypertension, and malignancy like lymphoproliferative disorders.

 

Ringewald et al. reported a high rate of rejection in nonadherent adolescent pediatric heart transplant recipients, which led to a high rate of death in this population[28]. The advances in immunosuppression coupled with a better understanding of rejection have resulted in improved survival, quality of life, and fewer adverse effects after transplantation. However, heart transplantation can be a solution for only a minority of end-stage HF patients owing to the scarcity of donor hearts and expert centers.

 

CONCLUSION:

The causes and clinical presentation of HF are different from adults. The overall outcome with HF is better in children than that in adults. There has been a significant advance in the evidence base for the management of HF in adults. While the general principles of management are similar to those in adults, there is a compelling need for larger and higher quality studies on the treatment of cardiac failure in children to provide a more comprehensive evidence .

 

REFERENCES:

1.     Dickstein K, CohenSolal A, Filippatos G, McMurray JJ, Ponikowski P, PooleWilson PA, et al. ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2008: The task force for the diagnosis and treatment of acute and chronic heart failure 2008 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association of the ESC (HFA) and endorsed by the European Society of Intensive Care Medicine (ESICM). Eur J Heart Fail 2008;10:93389.

2.     Hsu DT, Pearson GD. Heart failure in children: Part I: History, etiology, and pathophysiology. Circ Heart Fail 2009;2:6370.

3.     Kay JD, Colan SD, Graham TP Jr. Congestive heart failure in pediatric patients. Am Heart J 2001;142:9238.

4.     Massin MM, Astadicko I, Dessy H. Epidemiology of heart failure in a tertiary pediatric center. Clin Cardiol 2008;31:38891.

5.     Rossano JW, Kim JJ, Decker JA, Price JF, Zafar F, Graves DE, et al. Prevalence, morbidity, and mortality of heart failurerelated hospitalizations in children in the United States: A populationbased study. J Card Fail 2012;18:45970.

6.     Lipshultz SE, Sleeper LA, Towbin JA, Lowe AM, Orav EJ, Cox GF, et al. The incidence of pediatric cardiomyopathy in two regions of the United States. N Engl J Med 2003;348:164755.

7.     Andrews RE, Fenton MJ, Ridout DA, Burch M; British Congenital Cardiac Association. Newonset heart failure due to heart muscle disease in childhood: A prospective study in the United Kingdom and Ireland. Circulation 2008;117:7984.

8.     Towbin JA, Lowe AM, Colan SD, Sleeper LA, Orav EJ, Clunie S, et al. Incidence, causes, and outcomes of dilated cardiomyopathy in children. JAMA 2006;296:186776.

9.     Chaturvedi V, Saxena A. Heart failure in children: Clinical aspect and management. Indian J Pediatr 2009;76:195205.

10.  Jayaprasad N. Heart failure in children. Heart Views. 2016 Jul-Sep; 17(3): 92–99.

11.  Gulati A, Jabbour A, Ismail TF, et al. Association of fibrosis with mor- tality and sudden cardiac death in patients with nonischemic dilated cardiomyopathy. JAMA 2013;309:896-908.

12.  Dass S, Suttie JJ, Piechnik SK, et al. Myocardial tissue characterization using magnetic resonance noncontrast t1 mapping in hypertrophic and dilated cardiomyopathy. Circ Cardiovasc Imaging 2012;5:726-33.

13.  Hershberger RE, Lindenfeld J, Mestroni L, et al. Genetic evaluation of cardiomyopathy--a Heart Failure Society of America practice guide- line. J Card Fail 2009;15:83-97.

14.  Rossano JW, Jang GY. Pediatric heart failure: current state and future possibilities. Korean Circ J 2015;45:1–8.

15.  Ratnapalan S, Griffiths K, Costei AM, Benson L, Koren G. Digoxincarvedilol interactions in children. J Pediatr 2003;142:5724.

16.  Lewis AB, Chabot M. The effect of treatment with angiotensinconverting enzyme inhibitors on survival of pediatric patients with dilated cardiomyopathy. Pediatr Cardiol 1993;14:912.

17.  Leversha AM, Wilson NJ, Clarkson PM, Calder AL, Ramage MC, Neutze JM. Ef cacy and dosage of enalapril in congenital and acquired heart disease. Arch Dis Child 1994;70:359.

18.  Shaw NJ, Wilson N, Dickinson DF. Captopril in heart failure secondary to a left to right shunt. Arch Dis Child 1988;63:3603

19.  Frenneaux M, Stewart RA, Newman CM, HallidieSmith KA. Enalapril for severe heart failure in infancy. Arch Dis Child 1989;64:21923.

20.  Blume ED, Canter CE, Spicer R, Gauvreau K, Colan S, Jenkins KJ. Prospective singlearm protocol of carvedilol in children with ventricular dysfunction. Pediatr Cardiol 2006;27:33642.

21.  Azeka E, Franchini Ramires JA, Valler C, Alcides Bocchi E. Delisting of infants and children from the heart transplantation waiting list after carvedilol treatment. J Am Coll Cardiol 2002;40:20348.

22.  Hoffman TM, Wernovsky G, Atz AM, Kulik TJ, Nelson DP, Chang AC, et al. Ef cacy and safety of milrinone in preventing low cardiac output syndrome in infants and children after corrective surgery for congenital heart disease. Circulation 2003;107:9961002.

23.  Van der Bom T, Winter MM, Bouma BJ, et al. Effect of valsartan on sys- temic right ventricular function: a double-blind, randomized, place- bo-controlled pilot trial. Circulation 2013;127:322-30.

24.  Effect of enalapril on survival in patients with reduced left ventricu- lar ejection fractions and congestive heart failure. The SOLVD Investi- gators. N Engl J Med 1991;325:293-302.

25.  Rossano JW, Shaddy RE. Update on pharmacological heart failure therapies in children: do adult medications work in children and if not, why not? Circulation 2014;129:607-12.

26.  Stauffer BL, Russell G, Nunley K, Miyamoto SD, Sucharov CC. miRNA expression in pediatric failing human heart. J Mol Cell Cardiol 2013; 57:43-6.

27.  Miyamoto SD, Stauffer BL, Nakano S, et al. Beta-adrenergic adaptation in paediatric idiopathic dilated cardiomyopathy. Eur Heart J 2014;35: 33-41.

28.  Bernstein D, Fajardo G, Zhao M. The role of β-adrenergic receptors in heart failure: differential regulation of cardiotoxicity and cardioprotec- tion. Prog Pediatr Cardiol 2011;31:35-8.

 

 

 

 

 

 

Received on 20.11.2017             Modified on 20.12.2017

Accepted on 21.01.2018           © RJPT All right reserved

Research J. Pharm. and Tech 2018; 11(6): 2641-2646.

DOI: 10.5958/0974-360X.2018.00490.0