Introduction:
Imaging plays a major role in the evaluation of patients after cardiothoracic surgery, both in early post-operative monitoring and in evaluating suspected complications. Patients with post-operative complications can develop a variety of signs and symptoms, from hypotension (reduced blood pressure) and tachycardia secondary to severe bleeding to fever and leukocytosis (elevated white blood cell count) secondary to infection.
Radiologists are important members of the post-operative care team and help identify and treat complications of cardiothoracic surgery. This article provides an overview of the most common complications of cardiothoracic surgery and focuses on the role of imaging and diagnostic clues.
Why Is Post Operative Imaging Important in Cardiovascular Patients?
The importance of post-operative imaging in cardiovascular patients is listed below:
-
Radiologists have an important contribution to the post-operative care of patients undergoing cardiothoracic surgery.
-
Early detection of post-operative complications may reduce morbidity and mortality.
-
Chest imaging can identify, confirm the presence of, and, if suspected, further characterize post-operative complications of cardiothoracic surgery before they are clinically apparent.
-
Thorough knowledge of complications following cardiothoracic surgery and their respective manifestations is essential for radiologists to positively impact patient care.
What Are the Imaging Methods to Check Various Post-Operative Cardiovascular Complications?
The imaging methods to check various post-operative cardiovascular complications are listed below:
-
Chest Radiography and Fluoroscopy - A chest X-ray is usually one of the first tests, especially when complications in post-operative cardiovascular disease are first suspected. It is inexpensive, readily available, and rapidly provides information on heart and mediastinum size and composition, aortic arch, abdominal and thoracic location, pulmonary vessels, presence of calcifications or thoracic abnormalities, and postoperative changes. Fluoroscopy can help assess post-operative abnormalities, such as a barium esophagogram is used to determine hemi diaphragmatic paralysis (paralysis of one hemidiaphragm) or associated vascular abnormalities that compress the trachea and esophagus. Fluoroscopy is readily available and can play a role when obtaining a cardiac magnetic resonance imaging exam is difficult or in neonates for whom cardiac magnetic resonance imaging examination is difficult due to clinical conditions or sedation requirements.
-
Echocardiography - Transthoracic echocardiography provides crucial information on septal anatomy, right ventricle and left ventricle (chambers of the heart) size and function, tricuspid valve and pulmonary artery stenosis and regurgitation (artery carrying blood from the right ventricle of the heart to the lungs), proximal pulmonary artery anatomy and stenosis (narrowing), and aortic size and dysfunction. It is, therefore, the basis for pre-and post-operative cardiovascular imaging. Hemodynamics (blood flow) provides indicators such as estimated right ventricle and pulmonary pressure. It is also readily available, portable, reproducible, safe, widely used, and has good expertise among clinicians. Disadvantages of echocardiography include a limited acoustic window, especially in elderly and obese patients, an inability to provide reliable quantitative data on thoracic and post-operative abnormalities, right ventricular size and function, and the ability to repair.
-
Cardiac Magnetic Resonance (CMR) - CMR is extremely useful for preoperative and especially post-operative imaging in cardiovascular patients. CMR is non-ionizing radiation and can be performed regardless of patient size or image window. In contrast to echocardiography, which is used primarily qualitatively, CMR is an objective. It provides accurate and reproducible quantitative measurements. All parameters are essential for the long-term continuous tracking of cardiovascular conditions post-operatively. This test cannot be performed in case of gadolinium allergy, the presence of non-CMR pacemakers (a device used to control irregular heart rhythms) and defibrillators (a device that gives electrical pulse to the heart to restore heartbeat), renal failure, claustrophobia, and the need for sedation in younger patients. It also increases costs and requires knowledge of the both medical and technical staff for image acquisition and post-processing.
-
Cardiovascular Computed Tomography (CCT) - Multidetector CCT offers an excellent spatial and reasonable temporal resolution producing high-quality static and cine imaging as well as 3D reconstructions. It can be very helpful in the evaluation of complications occurring post-operatively. Compared to CMR, CCT provides better visualization of small blood vessels and aortic and pulmonary arteries and is less susceptible to stainless steel artifacts. It has shorter acquisition times and reduces the need for sedation. All these characteristics may prove important for some cardiovascular patients. Disadvantages of CCT include the inability to provide reliable flow or velocity data and the potentially risky use of ionizing radiation.
-
3-Dimensional Printing (3D) - 3D-printed reconstructions using high-resolution CT or contrast-enhanced MRI datasets from the blood pool have been reported for complex cardiovascular disease, especially surgical or transcatheter interventions. Although this technique is expensive, time-consuming, and requires considerable operator skill, such reconstructions are expected to be used more and more in the future as technology advances, especially when complex.
-
Nuclear Imaging - It is traditionally used in cardiovascular patients to examine the right ventricle, left ventricle, myocardial size, function, and viability at rest and during exercise, quantifies intracardiac shunts, and determines differential pulmonary perfusion between left and right lungs. It also allows assessment of lung ventilation and the ventilation-perfusion mismatch that is often present in chest and cardiovascular disease repaired due to post-operative abnormalities. Nuclear imaging is used sparingly and only in patients with clear CMR and cardiac CT contraindications.
-
Cardiac Catheterization and Angiocardiography (CCA) - These tests have been the cornerstones of cardiovascular disease diagnosis and treatment for the past many years. Still, this technique has gradually been superseded in the past few years since the development of non-invasive modalities (first echocardiography, more recently, CMR). Nevertheless, despite being invasive, CCA remains the gold standard for assessing intracardiac pressure, peripheral pulmonary arteries, and coronary arteries, and its use in this population is likely to increase with increasing age and an increase in the number of coronary artery diseases.
Conclusion:
Post-operative cardiovascular disease imaging relies on multiple imaging tools, which are used at varying frequencies depending on patient age, clinical concerns, availability, cost, and operator skill level. They are used to optimize the management, follow-up, and timing of interventions in these patients. Still, further investigation of factors influencing disease progression in cardiovascular conditions is warranted. Non-invasive techniques have both improved the diagnostic quality and reduced the risk from the diagnostic method.
