Analysis of Retinal Vessel Pulsations with Electrocardiographic Gating

Purpose The origin of retinal venous pulsations has been a matter of debate for some time. One classical explanation to the origin of these pulsations has been that the cardiac cycle induces systolic peaks in the intraocular pressure (IOP) which leads to decreases in retinal vein diameters. Recently, theoretical concepts have been published which postulate that IOP changes during the pulse cycle is not the primary driving force for venous pulsation, and hence, predict that the retinal vein diameter is indeed reduced during IOP diastole. The aim of the study was to test this hypothesis in a clinical trial. Subjects and Methods Continuous IOP and retinal vessel analyser (RVA) measurements were taken from 21 subjects, ages 20 to 30 years, with no known ophthalmologic diseases, while connected to a standard electrocardiograph (ECG). With this methodology, average and synchronised curves for the pulse cycle of IOP and retinal vessel pulsations were calculated for each subject. Each pulse cycle was standardised to 50 timepoints, which enabled direct phase shift comparisons. Results All subjects showed comparable results. Close to the optic disc (within 0 to 1.5 optic disc diameters away from the disc), retinal arteries led with the first peak at the 16/50 pulse cycle position, followed by IOP peak at the 23/50 cycle position, and then by veins at the 26/50 cycle position. Conclusion The present method indeed shows that retinal veins do not collapse when the IOP is highest, on the contrary, IOP and retinal vein diameters seem to be in phase, which lends support to the hypothesis that IOP is not the major driving force of the retinal vein pulsations.

MSCT imaging of various shunts and grafts in post operative cases of congenital heart diseases

Background: Multi-slice computed tomography (MSCT) plays an important role in clinical practice in assessing post-operative patients with complex CHD when echocardiography is not contributory. Despite the great capabilities of MR imaging for anatomic and functional assessment of the heart, it is time-consuming and may require a lengthy period of patient sedation; hence its use in seriously ill or uncooperative patients is often limited. CT has the advantages of widespread availability and short acquisition times. It is imperative for a radiologist to be aware of various palliative as well as corrective procedures and their various imaging findings. Aim of this article is to demonstrate and make one aware of various checklists and imaging findings in paediatric patients who have undergone various shunts and grafts at our tertiary cardiac care centre, their immediate as well as long term complications.Methods: We studied a total of 100 paediatric patients (<12 years old), who had undergone some sort of palliative or corrective shunt or graft placement, on MSCT during the period 2014 to 2018 at our tertiary cardiac care centre.Results: We try to outline details of various shunts and grafts used in congenital heart diseases correction, MSCT technique and imaging appearances and appearances of abnormal post-operative findings.Conclusions: Advances in computed tomography (CT) scanners and electrocardiographic gating techniques have resulted in superior image quality of the aorta and pulmonary arteries for evaluating postoperative congenital heart disease. MSCT is an excellent non-invasive modality for post-operative evaluation of various shunts and grafts.

Prognostic Performance of Prospective versus Retrospective Electrocardiographic Gating in Coronary Computed Tomographic Angiography

Coronary computed tomographic angiography (CCTA) with prospective electrocardiographic gating reduces radiation exposure, but its prognostic power for predicting cardiovascular risk in patients with suspected CAD has not been fully validated. To determine whether prospective gating performs as well as retrospective gating in this population, we compared these scan modes in patients undergoing 64-slice CCTA. From January 2009 through September 2011, 1,407 patients underwent CCTA; of these, 915 (mean age, 57.8 ± 13.5 yr; 54% male) had suspected coronary artery disease at the time of CCTA and were included in the study. Prospective gating was used in 195 (21%) and retrospective gating in 720 (79%). The mean follow-up duration was 2.4 ± 0.9 years. Overall, 390 patients (42.6%) had normal results on CCTA, 382 (41.7%) had nonobstructive coronary artery disease, and 143 (15.6%) had obstructive disease. Major adverse cardiac events occurred in 32 patients (3.5%): 11 cardiac deaths, 15 late revascularizations, and 6 nonfatal myocardial infarctions. Total event occurrences were similar in both groups (retrospective, 3.8%; prospective, 2.6%; P=0.42), as were the occurrences of each type of event. On adjusted multivariate analysis, nonobstructive (P=0.015) and obstructive (P &lt;0.001) coronary artery disease were independently associated with major adverse cardiac events. Scan mode was not a predictor of outcome. The mean effective radiation dose was 4 ± 2 mSv for prospective compared with 12 ± 4 mSv for retrospective gating (P &lt;0.01). The prognostic value of CCTA with prospective electrocardiographic gating compares favorably with that of retrospective gating, and it involves significantly less radiation exposure.