Cardiovascular imaging in children and adults following Kawasaki disease

Society for Cardiovascular Magnetic Resonance 2022 Cases of SCMR case series

"Cases of SCMR" is a case series on the SCMR website (https://www.scmr.org) for the purpose of education. The cases reflect the clinical presentation, and the use of cardiovascular magnetic resonance (CMR) in the diagnosis and management of cardiovascular disease. The 2022 digital collection of cases are presented in this manuscript.

Tolerability and efficacy of a reduced dose adenosine stress cardiac magnetic resonance protocol under general anesthesia in infants and children

BACKGROUND

Intravenous adenosine induces pharmacological stress by causing vasodilatation and thus carries the risk of severe hypotension when combined with vasodilatory effects of anesthetic agents.

OBJECTIVE

This study describes our experience with a reduced dose adenosine cardiac magnetic resonance imaging (MRI) protocol in young children under general anesthesia (GA).

MATERIALS AND METHODS

This is a retrospective report of all patients from birth to 18 years who underwent adenosine stress cardiac MRI under GA between August 2018 and November 2022. Based on our anecdotal experience of severe adverse effects in patients receiving adenosine infusion under GA and in discussion with the pediatric anesthesia team, we developed a modified protocol starting at a dose of 110 mcg/kg/min with incremental escalation to a full dose of 140 mcg/kg/min to achieve desired hemodynamic effect.

RESULTS

Twenty-two children (mean age 6.5 years, mean weight 28 kg) satisfied the inclusion criteria. The diagnoses included Kawasaki disease (7), anomalous aortic origin of left coronary artery (3), anomalous aortic origin of right coronary artery (2), coronary fistula (3), repaired d-transposition of great arteries (2), repaired anomalous left coronary artery from pulmonary artery (2), repaired truncus arteriosus with left coronary artery occlusion (1), extracardiac-Fontan with left coronary artery myocardial bridge (1), and post heart transplantation (1). Nine patients needed dose escalation beyond 110 mcg/kg/min. Two patients had transient hypotension during testing (systemic blood pressure drop > 25 mmHg). No patient developed significant heart block or bronchospasm. Six patients (repeat study in one) demonstrated inducible perfusion defects (27%) on stress perfusion sequences-5 of whom had confirmed significant coronary abnormalities on angiography or direct surgical inspection.

CONCLUSION

A reduced/incremental dose adenosine stress cardiac MRI protocol under GA in children is safe and feasible. This avoids severe hypotension which is both unsafe and may result in inaccurate data.

Distal coronary artery abnormalities in Kawasaki disease: experience on CT coronary angiography in 176 children

OBJECTIVE

Precise evaluation of coronary artery abnormalities (CAAs) in Kawasaki disease (KD) is essential. The aim of this study is to determine role of CT coronary angiography (CTCA) for detection of CAAs in distal segments of coronary arteries in patients with KD.

METHODS

CTCA findings of KD patients with distal coronary artery involvement were compared with those on transthoracic echocardiography (TTE) during the period 2013-21.

RESULTS

Among 176 patients with KD who underwent CTCA (128-Slice Dual Source scanner), 23 (13.06%) had distal CAAs (right coronary-15/23; left anterior descending-14/23; left circumflex-4/23 patients). CTCA identified 60 aneurysms-37 proximal (36 fusiform; 1 saccular) and 23 distal (17 fusiform; 6 saccular); 11 patients with proximal aneurysms had distal contiguous extension; 9 patients showed non-contiguous aneurysms in both proximal and distal segments; 4 patients showed distal segment aneurysms in absence of proximal involvement of same coronary artery; 4 patients had isolated distal CAAs. On TTE, only 40 aneurysms could be identified. Further, distal CAAs could not be identified on TTE. CTCA also identified complications (thrombosis, mural calcification and stenosis) that were missed on TTE.

CONCLUSIONS

CAAs can, at times, occur in distal segments in isolation and also in association with, or extension of, proximal CAAs. CTCA demonstrates CAAs in distal segments of coronary arteries, including branches, in a significant number of children with KD-these cannot be detected on TTE. CTCA may therefore be considered as a complimentary imaging modality in children with KD who have CAAs on TTE.

Exercise Stress Echocardiography in Kawasaki Disease Patients with Coronary Aneurysms

The most significant sequelae of Kawasaki disease (KD) are coronary artery aneurysms, which can lead to risk of future myocardial ischemia. Exercise stress echocardiography allows for non-invasive assessment of myocardial dysfunction. We reviewed our single center experience with exercise stress echocardiography in patients with previous history of KD with coronary aneurysms. We reviewed the records of 53 KD patients who underwent exercise stress echocardiography from 2000 to 2020. Abnormal stress echocardiograms were defined as those showing no increase in biventricular systolic function post-exercise or regional wall motion abnormalities. Computed tomography angiography and cardiac magnetic resonance imaging were reviewed for patients with abnormal stress echocardiograms. Clinical data were reviewed and correlated with stress echocardiogram results. Of the 53 patients, three (5.7%) had an abnormal exercise stress echocardiogram. All three patients were classified as AHA Risk Level 4 or 5 by coronary Z-score (internal dimension normalized for body surface area) and were confirmed to have coronary aneurysms, stenosis, or myocardial tissue perfusion defects on advanced cardiac imaging that could account for the results seen on stress echocardiogram. Exercise stress echocardiography detected signs of myocardial ischemia in a subset of high-risk patients with Kawasaki disease and coronary aneurysms and may be considered as a useful screening tool for this complex patient cohort.

Cardiac magnitude resonance findings of a patient with Kawasaki-giant coronary aneurysm and active myocarditis

Kawasaki disease is the most common vasculitis in children which can result in myocarditis in the acute phase and coronary artery aneurysms, as a major complication, in the sub-acute to chronic phase. We present a case of Kawasaki disease in the sub-acute phase with its features in cardiac MRI manifesting concomitant active myocarditis and giant coronary artery aneurysms.

Practical Workflow for Cardiovascular Assessment and Follow-Up in Kawasaki Disease Based on Expert Opinion

BACKGROUND

Approximately 25% of the patients with a history of Kawasaki disease (KD) develop coronary artery pathology if left untreated, with coronary artery aneurysms (CAA) as an early hallmark. Depending on the severity of CAAs, these patients are at risk of myocardial ischemia, infarction and sudden death. In order to reduce cardiac complications it is crucial to accurately identify patients with coronary artery pathology by an integrated cardiovascular program, tailored to the severity of the existing coronary artery pathology.

METHODS

The development of this practical workflow for the cardiovascular assessment of KD patients involve expert opinions of pediatric cardiologists, infectious disease specialists and radiology experts with clinical experience in a tertiary KD reference center of more than 1000 KD patients. Literature was analyzed and an overview of the currently most used guidelines is given.

CONCLUSIONS

We present a patient-specific step-by-step, integrated cardiovascular follow-up approach based on expert opinion of a multidisciplinary panel with expertise in KD.

Pediatric cardiothoracic vasculitis: multimodality imaging review

The pediatric vasculitides are a relatively uncommon and heterogeneous group of disorders characterized by vessel inflammation, often with cardiothoracic involvement. Diagnosis and monitoring are often clinically challenging because of the nonspecific symptoms and laboratory markers. Thus, imaging has assumed increasing importance for early detection of disease activity, extent and complications as well as long-term monitoring pre- and post-treatment. Herein, we review the major pediatric vasculitides with frequent chest manifestations, including Takayasu arteritis, Kawasaki disease, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, microscopic polyangiitis, Behçet disease and potential mimics. We highlight key clinical features and management considerations, emphasizing the central role of imaging.

Comparison of coronary artery measurements between echocardiograms and cardiac CT in Kawasaki disease patients with aneurysms

BACKGROUND

American Heart Association (AHA) guidelines for management of Kawasaki disease (KD) rely on coronary artery (CA) z-scores from echocardiograms. Compared with echocardiography, cardiac CT (CCT) offers better visualization of distal segments and evaluation for thrombosis and stenosis. Despite increasing use of CCT in KD, CA z-scores for CCT are not available and measurement concordance between imaging modalities is a critical knowledge gap.

METHODS

We retrospectively reviewed KD patients with CA aneurysms who had concurrent echocardiography and CCT between 2016 and 2020. Patients were included if they had history of CA z-scores of ≥3 on echocardiography during their clinical course. Agreement between CCT and echocardiography was assessed using Bland-Altman analysis.

RESULTS

Paired CCT and echocardiography studies were available in 18 patients (21 studies). The largest CA aneurysms were large/giant (z-score ≥10) in 14 studies, medium (z-score ≥5, <10) in 3 studies, and small (z score ≥2.5, <5) in 2 studies. Intra- and inter-observer reliability for CCT measurements were high for all CA segments (ICC 99.7% and 98.6%). For the LMCA, proximal LAD and proximal and distal RCA there was high correlation between echocardiogram and CCT absolute measurements with wider variation between modalities for the distal LAD and circumflex. Overall, CCT measurements tended to be smaller than echocardiogram measurements, and led to a lower AHA z-score risk classification in 24% of studies.

CONCLUSION

CCT and echocardiography have high agreement for absolute measurements of proximal CA segments, but more measurement discrepancy exists for distal CA segments with bias toward lower dimensions on CCT.

Systemic vasculitides and the role of multitechnique imaging in the diagnosis

Vasculitis, a systemic disease characterised by inflammation of the blood vessels, remains challenging to diagnose and manage. Vessel size has been the basis for classifying systemic vasculitides. Imaging plays a vital role in diagnosing this challenging disease. This review article aims (a) to summarise up-to-date literature in this field, as well as include classification updates and (b) to review available imaging techniques, recent advances, and emphasis on imaging findings to diagnose large vessel vasculitides.

Quantitative evaluation of coronary artery visibility on CT angiography in Kawasaki disease: young vs. old children

Coronary artery visibility on coronary CT angiography has rarely been investigated in young children with Kawasaki disease. This retrospective study was performed to quantitatively evaluate and compare coronary artery visibility with sufficient quality to measure it on coronary CT angiography among younger and older children with Kawasaki disease. Seventy-eight consecutive children with Kawasaki disease who underwent coronary CT angiography were divided into two groups: group 1 (age ≤ 6 years; n = 37) and group 2 (age > 6 years and < 18 years; n = 41). The visibility of the right coronary artery, left anterior descending artery, and left circumflex artery was quantitatively evaluated by dividing the length of the assessable coronary artery by the length of the corresponding groove, and compared between the two groups. The coronary artery visibility in group 1 was significantly lower than that in group 2 for the right coronary artery (77.8 ± 26.3% vs. 94.2 ± 13.6%, p < 0.002) and left anterior descending artery (54.8 ± 19.5% vs. 69.6 ± 21.3%, p < 0.003, but the difference was not significant for the left circumflex artery (43.7 ± 23.1% vs. 43.9 ± 26.7%, p > 0.9). In both groups, the visibility of the right coronary artery was the highest, followed by those of the left anterior descending artery and left circumflex artery. Compared with older children with Kawasaki disease, younger children with Kawasaki disease demonstrate significantly lower visibility of the right coronary artery and left anterior descending artery on coronary CT angiography. In contrast, the visibility of the left circumflex artery showed no significant difference between younger and older children with Kawasaki disease.

Potential Applications of PET Scans, CT Scans, and MR Imaging in Inflammatory Diseases: Part II: Cardiopulmonary and Vascular Inflammation

Detecting inflammation is among the most important aims of medical imaging. Inflammatory process involves immune system activity and local tissue response. The role of PET with fludeoxyglucose F 18 has been expanded. Systemic vasculitides and cardiopulmonary inflammatory disorders constitute a wide range of diseases with multisystemic manifestations. PET with fludeoxyglucose F 18 is useful in their diagnosis, assessment, and follow-up. This article provides an overview of the current status and potentials of hybrid molecular imaging in evaluating cardiopulmonary and vascular inflammatory diseases focusing on the potential for PET with fludeoxyglucose F 18/MR imaging and PET/CT scans.

Tales from the Night:: Emergency MR Imaging in Pediatric Patients after Hours

Overnight in-house radiology has rapidly become an important part of contemporary practice models, and is increasingly the norm in pediatric radiology. MR imaging is an indispensable first-line and problem-solving tool in the pediatric population. This has led to increasingly complex MR imaging being performed "after hours" on pediatric patients. This article reviews the factors that have led to widespread overnight subspecialty radiology and the associated challenges for overnight radiologists, and provides an overview of up-to-date imaging techniques and imaging findings of the most common indications for emergent MR imaging in the pediatric population.

Vascular imaging findings with high-pitch low-dose dual-source CT in atypical Kawasaki disease

PURPOSE

Determining the presence of aneurysms, thrombosis, and stenosis is very important for the diagnosis of atypical Kawasaki disease (AKD) and in the follow-up of AKD patients with aneurysms. We aimed to demonstrate high-pitch low-dose dual-source computed tomography (CT) angiography findings in pediatric patients with AKD.

METHODS

Over a 5-year period, high-pitch low-dose CT angiography was performed to determine vascular aneurysms or occlusions in 17 patients who had suspected AKD. The patients ranged from 2 months of age to 11.3 years, with a mean age of 3 years. The American Heart Association's criteria were used to diagnose AKD.

RESULTS

We did not detect any vascular problems in 6 of the patients, and they were not included in our study. Arterial aneurysms were present in 11 patients (aged 2 months to 11.3 years; mean age, 4.2 years; 7 males). In one patient, there was also a thrombus at an arterial aneurysm. Coronary artery aneurysms were detected in 7 patients and systemic artery aneurysms were detected in 7 patients. Three patients had both systemic and coronary aneurysms.

CONCLUSION

Our results suggest that high-pitch low-dose dual-source CT can detect all types of aneurysms, stenosis and occlusions of vessels in patients with AKD who were not previously diagnosed. This useful, easy, robust and fast technique may be preferred to diagnose AKD.

Myocardial Perfusion Reserve Index in Children With Kawasaki Disease

BACKGROUND

Coronary artery lesions in patients with Kawasaki disease (KD) can impair myocardial perfusion, yet evaluation of perfusion defects by cardiac magnetic resonance (MR) in children is often qualitative.

PURPOSE

In this study we aimed to use a quantitative method of myocardial perfusion using stress cardiac MR-derived myocardial perfusion reserve index (MPRI) in children with KD and compare MPRI with ventricular mechanical performance evaluated by cardiac MR strain analysis.

STUDY TYPE

This study was a retrospective review.

SUBJECTS

Twenty-one children with a diagnosis of KD who underwent stress perfusion cardiac MR were compared with nine controls.

FIELD STRENGTH/SEQUENCE

First-pass perfusion imaging using a T₁ -weighted gradient echo sequence was performed at rest and stress after administration of adenosine with 1.5T or 3T magnets.

ASSESSMENT

The MPRI was calculated as the ratio of maximum slope of myocardial enhancement during stress compared to rest and was evaluated with the American Heart Association 17 segment model.

STATISTICAL TESTS

Demographic and clinical characteristics among KD patients and controls were compared using Student's t-test for normally distributed continuous variables, Wilcoxon-rank sum test for nonnormally distributed variables, and χ² for categorical variables.

RESULTS

There was a significant decrease in MPRI in Segment 7 (1.53 vs. 2.23, P = 0.0058) in KD patients compared with controls. The reduction in MPRI in Segment 12 approached statistical significance (1.58 vs. 2.31, P = 0.0636). Three patients who underwent serial studies had decreased MPRI longitudinally. No differences were seen in circumferential or radial strain.

DATA CONCLUSION

MPRI shows impaired myocardial perfusion in patients with KD. MPRI can change over time, suggestive of progressive coronary artery changes, which may precede fibrosis and mechanical decline. MPRI can assess segmental and global perfusion defects in patients with KD and should be a part of routine cardiac MR evaluation in KD.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2017.

The emergence of Kawasaki disease in India and China

Kawasaki disease (KD) is recognized as a leading cause of acquired heart disease in children in developed countries. Although global in distribution, Japan records the highest incidence of KD in the world. Epidemiological reports from the two most populous countries in the world, namely China and India, indicate that KD is now being increasingly recognized. Whether this increased reporting is due to increased ascertainment, or is due to a true increase in incidence, remains a matter of conjecture. The diagnosis and management of KD in developing countries is a challenging proposition. In this review we highlight some of the difficulties faced by physicians in managing children with KD in resource-constrained settings.

Kawasaki disease and coronary artery aneurysms: from childhood to adulthood

Kawasaki disease is an acute, systemic vasculitis of childhood and confers a 25% risk of developing coronary artery aneurysms. Its etiology is unknown, but the incidence is increasing rapidly with linked gene polymorphisms having been identified. A constellation of symptoms, epidemics and seasonality all implicate an unidentified infective or environmental cause. Intravenous immunoglobulin therapy, aspirin and steroids all form the mainstay of acute treatment and reduces the incidence of coronary artery aneurysms if given before 7 days. However, in some, these lesions persist and require ongoing management during follow-up during childhood and into adult life. Evidence for further investigations in order to minimize complications is presented in order to minimize the myofibroblast proliferation and stenosis in the long term.

Dissecting Kawasaki disease: a state-of-the-art review

Kawasaki disease (KD) is a pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. The diagnosis is based on the presence of persistent fever and clinical features including exanthema, lymphadenopathy, conjunctival injection, and changes to the mucosae and extremities. Although the etiology remains unknown, the current consensus is that it is likely caused by an (infectious) trigger initiating an abnormal immune response in genetically predisposed children. Treatment consists of high dose intravenous immunoglobulin (IVIG) and is directed at preventing the development of CAA. Unfortunately, 10-20% of all patients fail to respond to IVIG and these children need additional anti-inflammatory treatment. Coronary artery lesions are diagnosed by echocardiography in the acute and subacute phases. Both absolute arterial diameters and z-scores, adjusted for height and weight, are used as criteria for CAA. Close monitoring of CAA is important as ischemic symptoms or myocardial infarction due to thrombosis or stenosis can occur. These complications are most likely to arise in the largest, so-called giant CAA. Apart from the presence of CAA, it is unclear whether KD causes an increased cardiovascular risk due to the vasculitis itself.

CONCLUSION

Many aspects of KD remain unknown, although there is growing knowledge on the etiology, treatment, and development and classification of CAA. Since children with previous KD are entering adulthood, long-term follow-up is increasingly important. What is known: • Kawasaki disease (KD) is a pediatric vasculitis with coronary artery damage as its main complication. • Although KD approaches its 50th birthday since its first description, many aspects of the disease remain poorly understood. What is new: • In recent years, multiple genetic candidate pathways involved in KD have been identified, with recently promising information about the ITPKC pathway. • As increasing numbers of KD patients are reaching adulthood, increasing information is available about the long-term consequences of coronary artery damage and broader cardiovascular risk.

Regression and Complications of z-score-Based Giant Aneurysms in a Dutch Cohort of Kawasaki Disease Patients

Kawasaki disease (KD) is a pediatric vasculitis. Its main complication is the development of coronary artery aneurysms (CAA), with giant CAA at the end of the spectrum. We evaluated regression and event-free rates in a non-Asian cohort of patients with giant CAA using the current z-scores adjusted for body surface area instead of absolute diameters. KD patients with giant CAA (z-score ≥10) visiting our outpatient clinic between January 1999 and September 2015 were included. Patient characteristics and clinical details were extracted from medical records. Regression was defined as all coronary arteries having a z-score of ≤3. A major adverse event was defined as cardiac death, myocardial infarction, cardiogenic shock, or any coronary intervention. Regression-free and event-free rates were calculated using the Kaplan-Meier method. We included 52 patients with giant CAA of which 45 had been monitored since the acute phase. The 1-, 2-, and 5-year regression-free rates were 0.86, 0.78, and 0.65, respectively. The 5-year, 10-year, and 15-year event-free rates were 0.79, 0.75, and 0.65, respectively. Four children, whose CAA would not have been classified as 'giant' based on absolute diameters instead of z-scores, had experienced an event during follow-up.

CONCLUSION

We found a high percentage of children in whom the lumen of giant CAA completely normalized. Four children not classified as 'giant' based on absolute diameters with z-scores of ≥10 experienced a cardiac event. Hence, the use of z-scores seems to be justified.

Stress perfusion magnetic resonance imaging to detect coronary artery lesions in children

BACKGROUND

Stress perfusion cardiovascular magnetic resonance (CMR) is used widely in adult ischemic heart disease, but data in children is limited. We sought to evaluate feasibility, accuracy and prognostic value of stress CMR in children with suspected coronary artery disease (CAD).

METHODS

Stress CMR was reviewed from two pediatric centers over 5 years using a standard pharmacologic protocol. Wall motion abnormalities, perfusion deficits and late enhancement were correlated with coronary angiogram (CAG) when available, and clinical status at 1 year follow-up for major adverse cardiovascular events (MACE; coronary revascularization, non-fatal myocardial infarction and death due to CAD) was recorded.

RESULTS

Sixty-four stress perfusion CMR studies in 48 children (10.9 ± 4.8 years) using adenosine; 59 (92%) and dipyridamole; 5 (8%), were reviewed. Indications were Kawasaki disease (39%), post arterial switch operation (12.5%), post heart transplantation (12.5%), post anomalous coronary artery repair (11%), chest pain (11%), suspected myocarditis or CAD (3%), post coronary revascularization (3%), and others (8%). Twenty-six studies were performed under sedation. Of all studies performed, 66% showed no evidence of ischemia or infarction, 28% had perfusion deficits and 6% had late gadolinium enhancement (LGE) without perfusion deficit. Compared to CAG, the positive predictive value (PPV) of stress CMR was 80% with negative predictive value (NPV) of 88%. At 1 year clinical follow-up, the PPV and NPV of stress CMR to predict MACE were 78 and 98%.

CONCLUSION

Stress-perfusion CMR, in combination with LGE and wall motion-analysis is a feasible and an accurate method of diagnosing CAD in children. In difficult cases, it also helps guide clinical intervention by complementing conventional CAG with functional information.

Kawasaki disease: etiopathogenesis and novel treatment strategies

INTRODUCTION

Kawasaki disease is an acute febrile systemic vasculitis that predominantly occurs in children below five years of age. Its etiopathogenesis is still not clear, but it is thought to be a complex interplay of genetic factors, infections and immunity. Areas covered: This review article discusses in detail Kawasaki disease, with particular emphasis on the recent updates on its pathogenesis and upcoming alternate treatment options. Though self-limiting in many cases, it can lead to severe complications like coronary artery aneurysms and thrombo-embolic occlusions, and hence requires early diagnosis and urgent attention to avoid them. Intravenous immunoglobulin (IVIG) with or without aspirin has remained the sole treatment option for these cases, but 10-15% cases develop resistance to this treatment. Expert commentary: There is a need to develop additional treatment strategies for children with Kawasaki disease. Targeting different steps of pathogenesis could provide us with alternate therapeutic options.

The Expanding Role of Imaging in Systemic Vasculitis

Various imaging modalities, including color duplex ultrasonography, CT angiography, magnetic resonance angiography, and PET, are emerging as important aids to the diagnosis, staging, evaluation of disease activity and response to treatment in systemic vasculitis. Although large-vessel vasculitis is the main target of imaging, refinement and increasing accuracy of imaging modalities are also providing useful information in the evaluation of medium-vessel and small-vessel vasculitis.

Sudden cardiac death from structural heart diseases in adults: imaging findings with cardiovascular computed tomography and magnetic resonance

Sudden cardiac death (SCD) is defined as the unexpected natural death from a cardiac cause within an hour of the onset of symptoms in the absence of any other cause. Although such a rapid course of death is mainly attributed to a cardiac arrhythmia, identification of structural heart disease by cardiovascular computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging is important to predict the long-term risk of SCD. In adults, SCD most commonly results from coronary artery diseases, coronary artery anomalies, inherited cardiomyopathies, valvular heart diseases, myocarditis, and aortic dissection with coronary artery involvement or acute aortic regurgitation. This review describes the CCT and CMR findings of structural heart diseases related to SCD, which are essential for radiologists to diagnose or predict.

Imaging of acquired coronary diseases: From children to adults

Acquired coronary diseases include aneurysms, fistulae, dissections, and stenosis. Aneurysms may occur secondarily to Kawasaki disease, a childhood vasculitis, the prognosis of which depends on the coronary involvement, or they may be degenerative, infectious, inflammatory, or traumatic in origin. Fistulae develop between the coronary arterial system and a pulmonary or bronchial artery, or cardiac cavity. Dissections may occur spontaneously or may be post-traumatic. These coronary abnormalities may be found incidentally or may present as complications, infarction or rupture. The goals of this article are to understand acquired childhood and adult coronary diseases and their usual means of presentation, the ways of investigating them, and the principles of their treatment.