Breath-hold MRI in evaluating patients with pectus excavatum

Case report: ventricular fibrillation and cardiac arrest provoked by forward bending in adolescent with severe pectus excavatum

Background

Life-threatening arrhythmias have been reported in patients with severe pectus excavatum in absence of other cardiac abnormalities. Literature is scarce regarding diagnosis, cause and management of this problem, particularly regarding the question as to whether the placement of an implantable cardioverter-defibrillator (ICD) is necessary.

Case summary

A 19-year-old male patient with severe pectus excavatum was scheduled for elective surgical correction. During forward bending for epidural catheter placement, syncope and ventricular fibrillation (VF) occurred resulting in cardiac arrest. After successful cardiopulmonary resuscitation, extensive analysis was performed and showed no cause for VF other than cardiac compression (particularly of the left atrium, right atrium, and ventricle to a lesser degree) due to severe pectus excavatum. Postponed correction by modified Ravitch was performed without ICD placement, with an uneventful post-operative recovery. Eighteen months after surgery, the patient remains well. Upon specific request, he did remember dizzy spells when tying shoelaces. He always considered this unremarkable.

Discussion

In severe pectus excavatum with cardiac compression, forward bending can decrease central venous return and cardiac output, causing hypotension, arrhythmia, and cardiac arrest. In absence of structural or electric abnormalities, cardiac compression by severe pectus excavatum was considered a reversible cause of VF and ICD placement unnecessary. Patients with cardiac compression due to severe pectus excavatum may report pre-existing postural symptoms upon specific request. When these postural symptoms are present, extreme and prolonged forward bending postures should be avoided.

Advancements in Methods and Camera-Based Sensors for the Quantification of Respiration

Assessment of respiratory function allows early detection of potential disorders in the respiratory system and provides useful information for medical management. There is a wide range of applications for breathing assessment, from measurement systems in a clinical environment to applications involving athletes. Many studies on pulmonary function testing systems and breath monitoring have been conducted over the past few decades, and their results have the potential to broadly impact clinical practice. However, most of these works require physical contact with the patient to produce accurate and reliable measures of the respiratory function. There is still a significant shortcoming of non-contact measuring systems in their ability to fit into the clinical environment. The purpose of this paper is to provide a review of the current advances and systems in respiratory function assessment, particularly camera-based systems. A classification of the applicable research works is presented according to their techniques and recorded/quantified respiration parameters. In addition, the current solutions are discussed with regards to their direct applicability in different settings, such as clinical or home settings, highlighting their specific strengths and limitations in the different environments.

Physician-Estimated Depth as a Screening Tool for Computed Tomography Evaluation of Pectus Excavatum

BACKGROUND

Pectus excavatum (PE) is the most common congenital chest wall anomaly with a reported incidence of 1/300 to 1/400 live births and a male predominance. Preoperative evaluation of defect severity typically requires a calculation of the Haller index (HI) and/or correction index (CI) using computed tomography (CT) or x-rays. The purpose of this study was to determine whether physician-estimated depth (PED), a bedside screening tool, could be used to identify a subset of pediatric patients in whom CT was unnecessary.

METHODS

After institutional review board approval (IRB #032018-091), we retrospectively reviewed all patients with a diagnosis of PE between 2009 and 2018 at our academic pediatric center. Demographic information including age, sex, and body mass index were abstracted. Imaging was reviewed to obtain HI and CI and to retrospectively calculate PED. The PED is calculated at the bedside by measuring the depth of the pectus at the site of greatest depression relative to a horizontal surface laid across the deformity. For this retrospective study, we calculated the CT-derived PED by measuring the depth from the horizontal on the respective CT images. Patients without imaging studies and patients with pectus carinatum, arcuatum, or mixed deformities were excluded from this study.

RESULTS

A total of 94 patients met inclusion criteria. Of these, 82% were male, with a median age of 15 y. Patients were further subdivided by BMI, with 46% of patients having a BMI of <18.5 kg/m² (i.e., underweight), whereas 54% of patients had a BMI of ≥18.5 kg/m². Using a threshold PED of 2 cm, patients with a BMI of <18.5 kg/m² had correct classification rates of 93% and 95% using PED relative to HI and CI, respectively. Patients with a BMI of ≥18.5 kg/m² had correct classification rates of 80% and 88% using PED relative to HI and CI, respectively, at the same 2 cm threshold.

CONCLUSIONS

PED is a viable screening tool for the preoperative evaluation of PE with a 2 cm threshold providing the combination of high sensitivity, specificity, and correct classification rates especially in underweight patients.

An Open, Prospective Study to Evaluate the Effectiveness and Safety of Hyaluronic Acid for Pectus Excavatum Treatment

Background

Pectus excavatum (PE) is sometimes associated with psychological and physiological difficulties influencing a patient’s quality of life. Treatment with a hyaluronic acid (HA)-based gel may benefit patients and be an alternative to other more invasive treatments.

Objectives

The authors sought to evaluate the effectiveness in terms of satisfaction, duration, and safety of HA gel treatment for PE including impact on quality of life.

Methods

Males ≥18 years having PE without functional problems received HA gel injections (50 – 150 mL) at the site of deformity and in some cases at the medial pectoralis muscle borders to optimize the aesthetic result. Follow-up visits were performed after 1, 3, 6, 12, and 24 months with optional retreatment at the 24-month visit including a 1-month follow-up. Evaluations included Pectus Excavatum Evaluation Questionnaire, patient satisfaction, magnetic resonance imaging, and safety assessments.

Results

The treatment significantly improved patients’ self-esteem (P < 0.001) and psychosocial function (P ≤ 0.038) throughout the study, as assessed by Pectus Excavatum Evaluation Questionnaire. Patients were satisfied with the aesthetic outcome and considered the treatment mild in terms of level of pain during injection. Treatment effects were maintained up to 24 months and 58% of the HA gel remained at this visit, shown by Magnetic Resonance Imaging measurements. The treatment was well tolerated.

Conclusions

Treatment of PE with HA gel improved patient quality of life related to self-esteem and psychosocial functioning including aesthetically pleasing results. The treatment may also offer benefits in terms of safety and tolerability compared with other treatments.

Level of Evidence: 4

Pectus Excavatum: A Review of Diagnosis and Current Treatment Options

Osteopathic medicine places a special emphasis on the musculoskeletal system, and understanding how chest wall structure may influence function is critical. Pectus excavatum is a common congenital chest wall defect in which the sternum is depressed posteriorly. Patients may present with complaints of chest wall discomfort, exercise intolerance, and tachycardia. The medical implications, diagnosis, and treatment options for patients with pectus excavatum are reviewed.

Options for assessing and measuring chest wall motion

Assessing chest wall motion is a basic and vital component in managing the child with respiratory problems, whether these are due to pathology in the lungs, airways, chest wall or muscles. Since the 1960s, clinical assessment has been supplemented with an ever-growing range of technological options for measuring chest wall motion, each with unique advantages and disadvantages. Measurements of chest wall motion can be used to: (1) Assess respiratory airflow and volume change, as a non-invasive alternative to measurement at the airway opening, (2) Monitor breathing over long periods of time, to identify apnoea and other types of sleep-disordered breathing, (3)Identify and quantify patterns of abnormal chest wall movement, whether between ribcage and abdominal components (thoracoabdominal asynchrony) or between different regions of the ribcage (eg in scoliosis and pectus excavatum). Measuring chest wall motion allows us to do things which simply cannot be done by more mainstream respiratory function techniques measuring flow at the airway opening: it allows respiratory airflow to be measured when it would otherwise be impossible, and it tells us how the different parts of the chest wall (eg ribcage vs abdomen, right vs left) are moving in order to generate that airflow. The basis of the different techniques available to assess and measure chest wall motion will be reviewed and compared, and their relevance to paediatric respiratory practice assessed.

Changes in chest compression indexes with breathing underestimate surgical candidacy in patients with pectus excavatum: a computed tomography pilot study

BACKGROUND

Haller Index (HI) ≥3.25 by computed tomography (CT) at end-inspiration has been used to indicate surgical correction in patients with pectus excavatum. However, chest wall diameters vary with breathing and may modify HI values and surgical indications. The aim of our study was to report the changes in HI with breathing and their impact in the surgical indication rates.

METHODS

Thirty six patients with pectus excavatum underwent chest CT evaluation at both end-inspiration and end-expiration. HI was derived by dividing the transverse diameter (TD) of the chest by the anteroposterior diameter (APD). Cardiac compression index (CCI) was then calculated by dividing the cardiac TD by the APD.

RESULTS

Mean patient age was 19 ± 7 years old and 86.8% were males. From end-inspiration to end-expiration, large changes in APD values corresponded to large changes (29.6%) in HI values. CCI increased significantly during end-expiration, primarily driven by an increase on the cardiac TD. Surgical indication was found in 71% and 91% of patients during end-inspiration and end-expiration, respectively (p<0.05).

CONCLUSIONS

This study showed that the severity indexes of the pectus excavatum were all significantly more severe at end-expiration than at end-inspiration, leading to an increase in surgical candidacy. We therefore recommend performing the CT at end-expiration.

Pulmonary embolism: a late complication of pectus excavatum repair

The Ravitch operation is frequently performed to correct pectus excavatum with few and minor complications. We present a case of pulmonary embolism with pulmonary endarterectomy in a patient undergoing Ravitch repair for pectus excavatum 2 years ago.

Chest fast MRI: an imaging alternative on pre-operative evaluation of Pectus Excavatum

BACKGROUND

Standard imaging methods in evaluating chest wall deformities, such as Pectus Excavatum (PE) in paediatric and adolescent patients, include baseline 2-view chest radiography and chest CT scan. Only few studies to date investigated the value of fast MRIin the pre operative assessment of patient affected by PE.

OBJECTIVE

To evaluate the efficacy of chest fast MRI in pre-operative management of patient affected by PE. To obtain the Haller Index (HI) and Asymmetry Index (AI) from chest fast MRI protecting patients from radiation exposure.

MATERIALS AND METHODS

We analyzed the data of 42 consecutive patients with severe PE who underwent minimally invasive repair between March 2007 and March 2010. All 42 patients received chest fast MRI, but only the first 5 in view of the results, were studied also with chest ultrafast CT scan. In both examinations, data at the deepest point of the depression were collected.

RESULTS

Severity indices of the deformity using HI and AI, collected from CT scan and fast MRI in the first 5 patients, were comparable. In the remaining 37 fast chest MRI offered good images of the chest wall deformities with no radiation exposure, detailing anatomical information such as displacement and rotation of the heart or great vessels anomalies.

CONCLUSION

This study suggests the use of chest MRI in pre operative workup for patients with PE to obtain severity indices (Haller Index and Asymmetry Index avoiding radiation exposure to paediatric patients.

MRI for the evaluation of pectus excavatum

Pectus excavatum, the most common congenital deformity of the anterior chest wall, is both a cosmetic and functional abnormality. The degree of abnormal chest wall deformity determines its functional effect, particularly its cardiac and pulmonary impact. Although CT scanning is the most widely used cross-sectional imaging technique used to measure the Haller index, the radiation exposure is reason to seek other alternatives. At our institution, we have introduced a rapid MRI technique for this purpose, which utilizes a single-axial 2-D FIESTA acquisition.

Correlation between sternal depression and cardiac rotation in pectus excavatum: Evaluation with helical CT

OBJECTIVE

The purpose of this study was to investigate the effect of the degree of sternal depression on the cardiac rotation of pectus excavatum as depicted with helical CT.

MATERIALS AND METHODS

Sixty-three patients (53 boys, 10 girls; mean age, 9.7 +/- 7 years) with pectus excavatum who underwent helical chest CT and surgical correction were included in this study. Depth of sternal depression, CT depression index, cardiac rotation angle, and pulmonary vein angle were measured, and the correlation of these parameters was analyzed.

RESULTS

The mean sternal depression was 21 +/- 7 mm; CT depression index, 2.7 +/- 1.4; cardiac rotation angle, 55 degrees +/- 9 degrees ; and pulmonary vein angle, 52 degrees +/- 12 degrees . The sternal depression (18 mm) in patients with a CT depression index less than 2.4 was less than that in patients with a CT depression index of 2.4-2.9 (sternal depression, 21 mm) or greater than 2.9 (sternal depression, 28 mm) (p < 0.01). Similarly, the cardiac rotation angle (49 degrees +/- 5 degrees ) in patients with a CT depression index less than 2.4 was smaller than that in patients with a CT depression index of 2.4-2.9 (55 degrees +/- 6 degrees ) or greater than 2.9 (64 degrees +/- 12 degrees ) (p < 0.01). The pulmonary vein angle in patients with a CT depression index less than 2.4 (59 degrees +/- 11 degrees ) was larger than that in patients with a CT depression index of 2.4-2.9 (50 degrees +/- 12 degrees ) or a CT depression index greater than 2.9 (45 degrees +/- 8 degrees ) (p < 0.01). Cardiac rotation angle had a positive correlation with CT depression index (r = 0.75, p < 0.01).

CONCLUSION

The degree of sternal depression has a positive correlation with the degree of cardiac rotation in pectus excavatum. Helical CT is a valuable technique for evaluating the chest deformity and resultant cardiac rotation.

A case of right ventricular dysfunction caused by pectus excavatum

Pectus excavatum compresses the underlying right side of the heart, which might lead to right ventricular dysfunction as illustrated in this case report.

Pathology of the thoracic wall: congenital and acquired

This review aims to cover the main congenital and acquired lesions that arise in the thoracic wall of infants and children. Imaging often plays an essential role in the evaluation of symptomatic and asymptomatic thoracic wall abnormalities. The use of appropriate imaging modalities for each condition will be addressed, as well as the range of benign and malignant conditions that can occur.

CINE-MRT des Thorax bei Patienten mit Pectus excavatum

BACKGROUND

Morphologic and dynamic assessment of respiratory chest kinetics was performed in patients with pectus excavatum deformity (PE) using dynamic MRI: cine MRI.

MATERIAL AND METHODS

Seven consecutive patients with PE (aged 20.3 years+/-4.0) and ten healthy volunteers of comparable age underwent real-time cine MRI of the chest during breathing on a 1.5 T MR scanner (Magnetom Sonata, Siemens Medical Systems, Erlangen, Germany) using a standard phased array body coil and a half-Fourier single-shot turbo spin echo sequence (HASTE) for dynamic imaging. During deep inspiration and expiration, single-shot sequences were performed in one slice level over 20 s at a frequency of 1 image/s covering the entire thoracic cage in three orientations. Morphology and chest kinetics in patients with PE were analyzed and compared with normal values, and typical patterns of chest kinetics were noted.

RESULTS

Three different types of chest morphology in PE were identified: (1) the generally flattened thoracic cage, (2) the "tilted" sternum, and (3) the focally deepened sternum. Three patterns of motion correspond to these morphological types: (1) elevation of the sternum and the anterior thoracic wall, (2) angulated elevation of the parasternal rib cage with persistent deepening of the sternum resembling a "wing beat" movement, and (3) increased diaphragmatic movements with limited chest wall dynamics.

CONCLUSIONS

Cine MRI is an adequate radiation-free diagnostic modality for the dynamic imaging of both chest morphology and chest wall kinetics in patients with PE. The pectus severity index can easily be determined and three typical movement patterns of chest wall kinetics identified.

Pectus excavatum with inspiratory inferior vena cava compression: a new presentation of pulsus paradoxus

A 29-year-old man with pectus excavatum presented with exercise intolerance, pulsus paradoxus, and paradoxically split S2. Chest computed tomography (CT) showed the heart shifted leftward and a pectus severity index of 7.18. Cardiopulmonary exercise study showed reduced VO2max, anaerobic threshold, and oxygen pulse. Echocardiography revealed a decline in mitral and tricuspid valve inflow, and stroke volume during inspiration. Cardiac extrinsic compression and anatomic cardiac abnormalities were not present. Dynamic magnetic resonance imaging (MRI) demonstrated inspiratory inferior vena cava (IVC) compression at the diaphragm. We discuss IVC compression by the diaphragm as a source of patient symptoms and as a mechanism for pulsus paradoxus associated with pectus excavatum.

Evaluation of Chest Motion and Volumetry During the Breathing Cycle by Dynamic MRI in Healthy Subjects

RATIONALE AND OBJECTIVES

To investigate diaphragm and chest wall motion during the whole breathing cycle using magnetic resonance imaging (MRI) and a volumetric model in correlation with spirometry.

MATERIALS AND METHODS

Breathing cycles of 15 healthy volunteers were examined using a trueFISP sequence (5 slices in 3 planes, 3 images per second). Time-distance curves were calculated and correlated to spirometry. A model for vital capacity (VC), continuous time-dependent vital capacity (tVC), and investigating the influence of horizontal and vertical parameters on tVC was introduced.

RESULTS

Time-distance curves of the breathing cycle using MRI correlated highly significant with spirometry (P < 0.0001). VC calculated by the model was similar to VC measured in spirometry (5.00 L vs. 5.15 L). tVC correlated highly significantly with spirometry (P < 0.0001). Vertical parameters had a more profound influence on tVC change than horizontal parameters.

CONCLUSIONS

Dynamic MRI is a simple noninvasive method to evaluate local chest wall motion and respiratory mechanics. It widens the repertoire of tools for lung examination with a high temporal resolution.