In medical research, there are studies which often collect data on categorical variables that can be summarized as a series of counts. These counts are commonly arranged in a tabular format known as a contingency table. The chi-square test statistic can be used to evaluate whether there is an association between the rows and columns in a contingency table. More specifically, this statistic can be used to determine whether there is any difference between the study groups in the proportions of the risk factor of interest. Chi-square test and the logic of hypothesis testing were developed by Karl Pearson. This article describes in detail what is a chi-square test, on which type of data it is used, the assumptions associated with its application, how to manually calculate it and how to make use of an online calculator for calculating the Chi-square statistics and its associated P-value.

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Sampling is one of the most important factors which determines the accuracy of a study. This article review the sampling techniques used in research including Probability sampling techniques, which include simple random sampling, systematic random sampling and stratified random sampling and Non-probability sampling, which include quota sampling, self-selection sampling, convenience sampling, snowball sampling and purposive sampling.

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The Bland–Altman plot is a method for comparing two measurements of the same variable. The concept is that X-axis is the mean of your two measurements, and the Y-axis is the difference between the two measurements. The chart can then highlight anomalies, for example, if one method always gives too high a result, then all points are above or below the zero line. It can also reveal that one method overestimates high values and underestimates low values. If the points on the Bland–Altman plot are scattered all over the place, above and below zero, then it suggests that there is no consistent bias of one approach versus the other. It is, therefore, a good first step for two measurement techniques of a variable.

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Linear regression is a statistical procedure for calculating the value of a dependent variable from an independent variable. Linear regression measures the association between two variables. It is a modeling technique where a dependent variable is predicted based on one or more independent variables. Linear regression analysis is the most widely used of all statistical techniques. This article explains the basic concepts and explains how we can do linear regression calculations in SPSS and excel.

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Regression analysis is using the relationship between a known value and an unknown variable to estimate the unknown one. Here, an estimate of the dependent variable is made corresponding to given values of independent variables by placing the relationship between the variables in the form of a regression line. To determine how well the regression line obtained fits the given data points, F-test of overall significance is conducted. The issues involved in the F-test of overall significance are many and mathematics involved is rigorous, especially when more than two variables are involved. This study describes in details how the test can be conducted and finally gives the simplified approach of test using an online calculator.

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Correlation is a statistical procedure to test the relationship between quantitative variables and categorical variables. In other words, it describes the degree of relation between two variables. It is one of the most commonly used statistical techniques. The present article is based on selected statistical textbook, review of the literature, and our own research experience study.

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Student's t-test is a method of testing hypotheses about the mean of a small sample drawn from a normally distributed population when the population standard deviation is unknown. In 1908 William Sealy Gosset, an Englishman publishing under the pseudonym Student, developed the t-test. This article discusses the types of T test and shows a simple way of doing a T test.

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Introduction: There are few data on heart failure (HF) burden and none available on the community prevalence of HF in India. We conducted a study aimed at determining the HF prevalence in a rural community as well as tertiary hospital care setting in North India. We also reviewed the existing literature regarding the estimated and projected prevalence of HF in India. Methodology: All adults (>20 years) with chronic breathlessness in six villages under a primary health care center in Northern India were identified and evaluated with standardized questionnaire and physical examination by trained health care workers. HF was diagnosed by standardized criteria and a transthoracic echocardiogram was performed in all subjects. In the hospital study, 500 consecutive patients presenting to our tertiary referral hospital were evaluated for the diagnosis of HF. For the systematic review, all published studies addressing HF or the burden of risk factors in India were identified. Projections for the absolute HF burden were made using local data and global studies of HF incidence, morbidity, and mortality. Results: Among the surveyed rural adult population of 10,163 patients, chronic breathlessness was present in 128 (1.3%). HF was present in 9% (n = 12), of which 67% (n = 8) had preserved left ventricular (LV) systolic function and 33% (n = 4) had LV systolic dysfunction. Therefore, the prevalence of HF in this general community was 1.2/1000. All patients with HF and preserved ejection fraction had poorly controlled hypertension. In the hospital study, of 500 consecutive patients, 20.4% had HF. Rheumatic heart disease (52%) was the most common cause followed by ischemic heart disease (17%). The mean age of presentation was 39 ± 16 years. The prevalence of HF in the outpatient department patients was 22.5% below 30 years and 14.9% above 50 years, reflecting the young population of HF. For the estimates concerning HF burden in India, projections were made using both age-specific extrapolations from developing countries and data regarding development of HF in the presence of risk factors. The estimated prevalence of HF is about 1% of the total population or about 8–10 million individuals. The estimated mortality attributable to HF is about 0.1–0.16 million individuals per year. Conclusions: While our hospital data are consistent with the HF burden and etiology expected in a government tertiary hospital setting, our community-based study is the first of its kind reported from India. The community study demonstrates a surprisingly low prevalence of symptomatic HF in the surveyed villages. This could be partially explained by the rural farming-based community setting but is also likely due to under-reporting of symptoms. Our review of the projected national estimates suggests an alarming burden of HF in India despite a younger population than the developed nations. A significant proportion of this burden may be preventable with better screening and early and adequate treatment of the risk factors.

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For a long-time men had a philosophic view of health and disease, and this lasted till almost 2500 years back. Hippocrates, the great Greek physician, is believed to have seperated the "art of healing" and philosophy. An astute observer, Hippocrates during his practice employed principles that laid the foundation of modern medicine. The medical fraternity worldwide unanimously bestowed the title of "father of medicine" to this great man. Apart from being a physician, he was instrumental in bringing about the concept of ethics in the realm of medicine. The famous document "Hippocratic Oath" while being respected by almost all has generated a great amount of debate among historians. Nonetheless, almost all medical schools across the world have the Oath ceremony where medical graduates agree to the commandments of the Hippocratic Oath, either in its original or modified form. Although a statement of promise this Oath does not have any legal implications as might be seen by a person outside the medical community. This article outlines the contributions made by Hippocrates to the medical world with an emphasis on the Hippocratic Oath.

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Background: The selection of the correct donor lung is crucial for a successful lung transplant. Since the median survival after lung transplant is 5 years and the morbidity and mortality of lung transplant is higher than other transplants, it is crucial to preselect the correct recipient. Methodology: In India, Dr. P. Venugopal at the All India Institute of Medical Sciences, New Delhi, performed the first successful heart transplant, while Dr. K. M. Cherian performed the first heart–lung transplant at Chennai. At Apollo Hopsitals, Chennai, the first heart transplant was performed by Dr. M. R. Girinath. Subsequently, the Department of Heart and Lung Transplantation at Apollo Hospitals, Chennai, have performed a large number of heart and lung transplants and its experience is summarized. Results: The Department of Heart and Lung Transplantation at Apollo Hospitals, Chennai, has done 101 lung and 62 heart transplants as part of their lung and heart lung transplant program. There were 21 heart–lung transplants and 25 double lung transplants. The results are discussed and indications, contraindications for lung and heart–lung transplant as well as recipient and donor workup are discussed in this first part of a set of three articles. Conclusions: Careful selection of a recipient and donor leads to a successful lung and heart–lung transplant program.

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This is a bedside case discussion of a patient presenting with acute myocardial infarction. The symptoms and signs are discussed. The choices at each stage, the electrocardiogram (ECG), the angiogram, and the therapeutic findings are discussed in detail. The context with reference to India is also discussed. The differential diagnosis of the history of presentation is also discussed. ECG localization of myocardial infarction, management of acute coronary occlusion, and medical management of myocardial infarction are discussed.

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A patient of dominant right sided heart failure for 7 years is presented and discussed, starting from the history and examination findings and going on to all the investigations. The clinical findings, along with the electrocardiogram, chest X-ray, echocardiogram, and cardiac computed tomography are used to arrive at a diagnosis of chronic constrictive pericarditis. The differential diagnosis at each stage of presentation are presented and discussed.

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A 27-year-old female presented with generalized body swelling and progressive shortness of breath for the past 4 months. On examination, she had a loud continuous murmur, elevated jugular venous pressure, and gross ascites. The examination findings, electrocardiogram, chest radiography, and echocardiogram are discussed in a step-wise manner to arrive at a diagnosis and plan of management of a patient with ruptured sinus of Valsalva aneurysm is discussed along with review of relevant literature.

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The potential source of complexity while analyzing the data is to choose on whether the data collected could be analyzed properly by the application of parametric tests or nonparametric tests. This concern cannot be underrated as there are certain assumptions which should be fulfilled before analyzing the data by applying either of the two types of tests. This article describes in detail the difference between parametric and nonparametric tests, when to apply which and the advantages of using one over the other.

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Kussmaul's has provided us with three important signs: Pulses paradoxus, Kussmaul's sign and Kussmaul Breathing. This article discusses Kussmaul's sign, its discovery, first description, pathophyiology and exceptions.

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A adult patient presented with cyanosis since early childhood. The clinical approach to such a patient, including review of the ecg, chest xray and echocardiogram is presented. Various aspects of the bedside approach to adult cyanotic heart disease are discussed

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Prosthetic heart valve thrombosis incidence is high in developing countries and contributes to significant late mortality postvalve surgery. Many guidelines advocate surgery as the first line therapy though thrombolysis is often used in many centers. In this article, we review the newer regimens of fibrin-specific thrombolytics. Newer regimens of very low-dose, slow infusion lead to equal efficacy with lower complication in majority of patients. Patients with the New York Heart Association (NYHA) Class I–II who have low thrombus burden should receive thrombolysis with low-dose slow infusion while those with high thrombus burden should be planned for surgery. Patients presenting with NYHA Class IV should be treated with classical dose thrombolysis.

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The historical evolution of the prosthetic heart valves from the first attempts with the Hufnagel's valve in the treatment of the aortic insufficiency to the Starr-Edwards' ball valve and later the tilting disc valves (Bjork-Shiley etc.,) and finally the bileaflet valves (St. Jude) are discussed. The Indian contribution with Chitra valve is also described.

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A 24-year-old female with rheumatic heart disease presents with a 6 years history of symptoms, with an eventful pregnancy, medical management, and subsequent surgery. The history and management is discussed.

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Organ donation is one of the greatest medical marvels of the twentieth century which has saved the lives of several patients. The disparity between the huge demands for the organs and their poor supply is the main issue. The total organ donation shortage in our country can be met even if only few victims involved in fatal accidents serve as organ donors. Organ donation and successful retrieval of life saving organs is a complex process involving co-ordination of multiple transplant teams. This article reviews the different kinds of organ donors, evolution and present status of organ donation program in India, legal aspects of organ donation, process of pledging organs by a living person and the efforts taken to promote awareness about organ donation.

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Heart failure (HF) is a major health problem in India with a postadmission mortality of 20%–30%. Medication adherence ranges from 25% to 50%, and the tolerance of guideline-based medication is low for Indian patients. We took out guidelines on HF in 2015, and this update covers the changes which have occurred in HF management in the past 2 years. As a number of new drugs such as angiotensin receptor-neprilysin inhibitor and ivabradine have been approved for use in India, devices such as implantable cardioverter-defibrillators and cardiac resynchronization therapy are becoming more accessible and more left ventricular assist devices and transplants are being done in India, there is need for clear guidelines for the use of each which are practical for India.

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Phenoxybenzamine (PBZ) is an alpha adrenergic antagonist, used for the management of hypertension. PBZ acts by blocking alpha-adrenergic receptors, leading to vasodilatation and low systemic vascular resistance. This helps in control of blood pressure in pheochromocytoma, improvement of systemic oxygen delivery, and optimization of the Qp/Qs in pediatric cardiac surgery such as hypoplastic left heart syndrome and improving perfusion parameters during open heart surgery. The uses have further extended to causalgia, Raynaud's phenomenon, autonomic hyperreflexia, and even for patency of radial artery conduit in coronary artery bypass grafting surgery. However, its prolonged hypotensive effect limits the regular use. In this review, we discussed the mechanism of action, pharmaco-physiology of PBZ, perioperative uses in different clinical setting and controversies for its uses; publications in different scientific journals from the previous years.

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The new US blood pressure guideline lowers the definition of high blood pressure to 130/80 mm Hg.The new guideline adopts a key component of the 2013 cholesterol guideline and incorporates overall cardiovascular risk. The AAFP has decided to not endorse the recent hypertension guideline because it gave undue importance to the SPRINT trial and cardiovascular risk which was not validated and would lead to overtreatment. The guidelines are discussed in this article.

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Introduction: Heart Transplant in India started in 1994. We were initially doing 1-2 per year but the numbers have picked up since 2014 and we have done 25 in the past 3 years. We describe our experience of the last 4 years in this paper. Results: Initially, we experienced a relatively higher rate of rejections, fungal infections and graft failure. As we changed protocols, stopped using induction therapy except in high risk, maintained higher levels of immune suppression and tapered steroids faster in the first year, the complications reduced. All patients who had rejections and all the later transplants were maintained on a regime of tacrolimus, mycophenolate mofetil and steroids along with six months of valgancyclovir, voriconazole and co-trimoxazole. Steroids were tapered by six months to 0.1 mg/kg per day in all patients. Conclusions: In our recent patients, infection was the most common adverse event followed by rejection and PGD. In the latter half of our experience, we found that the complications reduced, suggesting that experience leads to less complications.

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A 29-year-old female had presented with dyspnea on exertion since she was 10 years old, with sudden worsening for 5 months along with palpitations on exertion for the past 5 months. The examination findings, electrocardiogram, chest X-ray, and echocardiogram are discussed in a stepwise manner to arrive at a diagnosis and plan the management of a patient with rheumatic heart disease with multivalvular lesions. Relevant literature is also reviewed.

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