Sahadev T Reddy

Contrast-enhanced CMR is equally effective as TEE in the evaluation of left atrial appendage thrombus in patients with atrial fibrillation undergoing pulmonary vein isolation procedure

BACKGROUND Patients with atrial fibrillation (AF) routinely undergo transesophageal echocardiography (TEE) for the evaluation of the left atrial appendage (LAA) to rule out thrombus prior to undergoing pulmonary vein isolation (PVI). Cardiac magnetic resonance (CMR) is now increasingly used for the evaluation of patients with AF to define pulmonary vein (PV) anatomy prior to PVI. OBJECTIVE To hypothesize that a retrospective comparison of 2-dimensional/3-dimensional (2D/3D) contrast-enhanced CMR sequences with TEE for the evaluation of LAA thrombus in patients with AF selected for PVI will demonstrate equivalence. METHODS Ninety-seven (N = 97) consecutive patients with AF underwent near-simultaneous TEE and noncontrast and contrast CMR prior to undergoing an initial PVI procedure. The CMR images were analyzed in 2 categories: (1) the 2D noncontrast cine images and early gadolinium enhancement images showing LAA and (2) 3D contrast source images acquired during PV magnetic resonance angiography. CMR variables evaluated were the presence or absence of LAA thrombus and the quality of images, and they were compared with the results of TEE in a blinded fashion. RESULTS All subjects were analyzed for the presence or absence of LAA thrombus. Thrombus was absent in 98% of the patients on both TEE and CMR and present in 2% on both studies (100% correlation). In 6 subjects, 2D cine CMR images were indeterminate whereas all 2D early gadolinium enhancement images and 3D contrast images were successful in excluding LAA thrombus. There was 100% concordance between CMR and TEE for the final diagnosis of LAA thrombus. CONCLUSIONS In one single examination, CMR offers a comparable alternative to TEE for the complete noninvasive evaluation of LAA thrombus and PV anatomy in patients with AF referred for PVI without obligate need for TEE.

Ex vivo cardiovascular magnetic resonance measurements of right and left ventricular mass compared with direct mass measurement in excised hearts after transplantation: a first human SSFP comparison

BackgroundCMR is considered the `gold standard’ for non-invasive LV and RV mass quantitation. This information is solely based on gradient-recalled echo (GRE) sequences while contrast dependent on intrinsic T1/T2 characteristics potentially offers superior image contrast between blood and myocardium. This study aims, for the first time in humans, to validate the SSFP approach using explanted hearts obtained from heart transplant recipients. Our objective is establish the correlation between and to validate steady-state free precession (SSFP) derived LV and RV mass vs. autopsy mass of hearts from cardiac transplants patients.MethodsOver three-years, 58 explanted cardiomyopathy hearts were obtained immediately upon orthotopic heart transplantation from the OR. They were quickly cleaned, prepared and suspended in a saline-filled container and scanned ex vivo via SSFP-SA slices to define LV/RV mass. Using an automatic thresholding program, segmentation was achieved in combination with manual trimming (ATMT) of extraneous tissue incorporating 3D cardiac modeling performed by independent and blinded readers. The explanted hearts were then dissected with the ventricles surgically separated at the interventricular septum. Weights of the total heart not excluding papillary and trabecular myocardium, LV and RV were measured via high-fidelity scale. Linear regression and Bland-Altman plots were used to analyze the data. The intra-class correlation coefficient was used to assess intra-observer reliability.ResultsOf the total of 58 explanted hearts, 3 (6%) were excluded due to poor image quality leaving 55 patients (94%) for the final analysis. Significant positive correlations were found between total 3D CMR mass (450 ± 111 g) and total pathology mass (445 ± 116 g; r = 0.99, p < 0.001) as well as 3D CMR measured LV mass (301 ± 93 g) and the pathology measured LV mass (313 ± 96 g; r = 0.95, p < 0.001). Strong positive correlations were demonstrated between the 3D CMR measured RV mass (149 ± 46 g) and the pathology measured RV mass (128 ± 40 g; r = 0.76, p < 0.001). The mean bias between 3D-CMR and pathology measures for total mass, LV mass and RV mass were: 3.0 g, -16 g and 19 g, respectively.ConclusionsSSFP-CMR accurately determines total myocardial, LV and RV mass as compared to pathology weighed explanted hearts despite variable surgical removal of instrumentation (left and right ventricular assist devices, AICD and often apical core removals). Thus, this becomes the first-ever human CMR confirmation for SSFP now validating the distinction of `gold standard’.

Exploratory use of cardiovascular magnetic resonance imaging in liver transplantation: a one-stop shop for preoperative cardiohepatic evaluation.

Background Preoperative cardiovascular risk stratification in orthotopic liver transplantation candidates has proven challenging due to limitations of current noninvasive modalities. Additionally, the preoperative workup is logistically cumbersome and expensive given the need for separate cardiac, vascular, and abdominal imaging. We evaluated the feasibility of a “one-stop shop” in a magnetic resonance suite, performing assessment of cardiac structure, function, and viability, along with simultaneous evaluation of thoracoabdominal vasculature and liver anatomy. Methods In this pilot study, patients underwent steady-state free precession sequences and stress cardiac magnetic resonance (CMR), thoracoabdominal magnetic resonance angiography, and abdominal magnetic resonance imaging (MRI) on a standard MRI scanner. Pharmacologic stress was performed using regadenoson, adenosine, or dobutamine. Viability was assessed using late gadolinium enhancement. Results Over 2 years, 51 of 77 liver transplant candidates (mean age, 56 years; 35% female; mean Model for End-stage Liver Disease score, 10.8; range, 6–40) underwent MRI. All referred patients completed standard dynamic CMR, 98% completed stress CMR, 82% completed late gadolinium enhancement for viability, 94% completed liver MRI, and 88% completed magnetic resonance angiography. The mean duration of the entire study was 72 min, and 45 patients were able to complete the entire examination. Among all 51 patients, 4 required follow-up coronary angiography (3 for evidence of ischemia on perfusion CMR and 1 for postoperative ischemia), and none had flow-limiting coronary disease. Nine proceeded to orthotopic liver transplantation (mean 74 days to transplantation after MRI). There were six ascertained mortalities in the nontransplant group and one death in the transplanted group. Explant pathology confirmed 100% detection/exclusion of hepatocellular carcinoma. No complications during CMR examination were encountered. Conclusions In this proof-of-concept study, it appears feasible to perform a comprehensive, efficient, and safe preoperative liver transplant imaging in a CMR suite—a one-stop shop, even in seriously ill patients.

Ventricular Tachycardia and Right Ventricular Fibrosis After Tetralogy of Fallot Surgical Repair

Ventricular tachyarrhythmias are known sequelae among adults with repaired tetralogy of Fallot. The incidence of sustained ventricular tachycardia and sudden cardiac death in patients 35 years after corrective surgery is estimated at 11.9% and 8.3%, respectively.1 Studies have shown that right ventricular enlargement resulting from chronic pulmonic regurgitation is the most common hemodynamic substrate.2 QRS prolongation (>180 milliseconds) is one of the most sensitive ECG predictors and in turn correlates with right ventricular (RV) dilation.3 The exact mechanism is not as well studied as that of left ventricular arrhythmias, but it is purported that volume overload leads to RV myocardial stretching and RV fibrosis and hence serves as an arrhythmogenic focus. The anatomic location of the RV pathology leading to ventricular tachyarrhythmias after tetralogy of Fallot surgical repair is not well defined. The basal portions of the RV …

Evaluation of cardiac valvular regurgitant lesions by cardiac MRI sequences: comparison of a four valve semi-quantitative vs. quantitative approach.

BACKGROUND AND AIM OF THE STUDY Cardiac magnetic resonance (CMR) imaging generally allows a more accurate and valid quantification of cardiac function, mass and regurgitant volumes than echocardiography. Although recent technological advancements in CMR have made the evaluation of cardiac valves more reliable, no studies have yet been conducted to compare semi-quantitative grading (SQG) using CMR steady-state free precession (SSFP) sequences with quantitative grading (QG) based on stroke volumes and phase-velocity mapping (PVM). It is proposed that the SQG of cardiac valvular regurgitations based on CMR SSFP sequences is feasible, and highly correlative with standard CMR QG methods. METHODS CMR data obtained between January 2007 and December 2011 was evaluated prospectively for valvular regurgitant lesions. Patients were included if they had right and left ventricular volumetrics based on CMR SSFP sequences and PVM across the aortic and pulmonic valves with reported regurgitant volumes and fractions. Patients were excluded if they had prosthetic valves, cardiac arrhythmias and intra-cardiac shunts. Regurgitant lesions were semi-quantitatively (visually) graded on a standard scale of 0 to 4 (trace, mild, moderate, moderate to severe, and severe) and compared with quantitative regurgitant fractions. Correlations were evaluated by Spearmans rho formula, and kappa for intra- and inter-observer variabilities were obtained on 30% of the study sample. RESULTS A total of 97 patients (58 males, 39 females; average age 55 +/- 18 years) representing 134 valvular regurgitations [mitral (MR), aortic (AR), tricuspid (TR), and pulmonary (PR)] were analyzed by semiquantitative and quantitative methods. The regurgitant lesions included 44 mitral, 50 aortic, 29 tricuspid, and 11 pulmonary. The correlation between SQR versus QG yielded the following results: 0.67, p < 0.001 (MR, r = 0.66, p < 0.001; AR, r = 0.68, p < 0.002; TR, r = 0.68, p = 0.001; PR, r = 0.70, p = 0.017). The results for QG versus SQG accounting for clinically significant differences of +/- 1 grade for the group were as follows: 0.95, p < 0.001 (MR, r = 0.91, p < 0.001; AR, r = 0.96, p < 0.001; TR, r = 0.99, p < 0.001; PR, r = 0.93, p < 0.001). No discrepancy between surgical regurgitation was present (3+ versus 4+). Weighted kappa results were 0.67 and 0.61 for intra- and inter-observer variabilities. CONCLUSION The visual assessment of cardiac regurgitant lesions is reliable, accurate and reproducible when compared to formal quantitative analysis via CMR. This confirms a robust role for CMR in assessing regurgitant lesions, particularly for surgical decision-making. These results were applicable to patients in sinus rhythm at the time of scanning.

Imaging the PM/AICD patient; fancy or fanatical?

Background Imaging patients with a pacemaker or AICD has always been taboo in the MRI environment. However, with current improvements in pacemaker lead and generator development along with very vigilant and knowledgeable personnel in pacemaker safety, MRI procedures can be implemented successfully. However, safe performance, not withstanding the risks, leads one to question if the results from the scans provide additional valuable clinical information to warrant the risk. Hypothesis: We propose that MRI imaging patients with a pacemaker can be crucial to establish clinical diagnosis. Methods A total of 25 patients were imaged on a GE CV/i Excite Version 12, 1.5 T system (GE, Milwaukee, WI). Three patients had an AICD, 4 patients had an AICD/Pacemaker, 2 patients had a single pacemaker lead and the remaining 16 patients had a complete pacemaker implantation. Each patient was performed in the dedicated Cardiac MRI Imaging Suite under the strict supervision of the Cardiologist. EP Lab personnel were present and reconfigured the pacemaker into an appropriate asynchronous mode under the guidance of the Cardiologist. The MRI scan sequences were selected such that the SAR level was lower or equal to 2.0 W/kg. to reduce additional heating to the device. Results All patients completed the procedure with no adverse events and the pacemaker was interrogated after the procedure by EP Lab and reprogrammed under the direction of the Cardiologist. Impedance, thresholds, amplitudes and shock impedances were unchanged pre to post scanning. The average MRI scan time was 20±55min. Regarding the population, of the 25 patients imaged, 17 (68%) were neurology cases and 8(32%) were cardiac cases. After reviewing the results from the 17 neurology cases and comparing the results from prior studies (CT, angio and/or myelogram) 14 (82%) out of the 17 patients benefited from having this procedure. 12 (70%) out of the 17 patients altered the diagnosis for a better outcome in patient care. The remaining 3(18%) patients did not show additional information that enhanced the diagnosis. The 8 cardiac cases were also compared to prior studies (heart cath, TEE, TTE and stress) and the outcome of all patients’ diagnosis was shown to be enhanced by the MRI imaging. In 4(50%) of the 8 patients CMR altered the prevailing clinical diagnosis. Thus, a total of 22 patients (88%) benefited by enhancement or alteration of the original diagnosis while 3(12%) patients did not provide any additional information. Conclusions The use of PM/AICD imaging in MRI remains controversial but as the lead/generator technology has improved, increased confidence in its use is found. Herein, we show that MRI procedures on carefully selected patients with pacemakers/AICD’s are beneficial and substantially enhance or alter patient diagnosis. We propose that not only are Pacemakers/AICD’s no longer taboo in the MRI environment but they can be markedly efficient with lifealtering and life-saving consequences. Funding None.

A SYSTEMATIC REVIEW FOR SUDDEN CARDIAC DEATH IN HYPERTROPHIC CARDIOMYOPATHY PATIENTS WITH MYOCARDIAL FIBROSIS: A CMR LGE STUDY

Hypetrophic Cardiomyopathy is the most common genetic cardiac disease that affects cardiac sarcomere, resulting in myocardial disarray. Affected patients have an predisposition for malignant ventricular tachyarrythmias and consequently, sudden cardiac death(SCD). In some single center studies, late

Left atrial appendage myxofibrosarcoma: A rare masquerader of myxoma and thrombus-“all that glitters is not gold”

Left atrial appendage mass can occasionally pose a serious challenge to physicians to identify the nature of the mass with the aid of imaging techniques. We present a case of 67‐year‐old man, who was evaluated for suspected left atria myxoma. Transesophageal echocardiography revealed a heterogeneous density originating from left atrial appendage, thought to be most consistent with a myxoma. Cardiac magnetic resonance imaging, uncharacteristically, gave an equivocal picture, suggesting the mass to be a myxoma on initial imaging and a thrombus with evidence of liquefaction necrosis following postcontrast enhancement. Surprisingly, histopathology of the mass following its surgical excision yielded a rare diagnosis of myxofibrosarcoma.

Cardio-hepatic risk assessment by CMR imaging in liver transplant candidates

The preoperative workup of orthotopic liver transplantation (OLT) patients is practically complex given the need for multiple imaging modalities. We recently demonstrated in our proof‐of‐concept study the value of a one‐stop‐shop approach using cardiovascular MRI (CMR) to address this complex problem. However, this approach requires further validation in a larger cohort, as detection of hepatocellular carcinoma (HCC) as well as cardiovascular risk assessment is critically important in these patients. We hypothesized that coronary risk assessment and HCC detectability is acceptable using the one‐stop‐shop CMR approach.

Evaluation of congenital aortic valve anomalies by cardiac Mri

Cardiac magnetic resonance (CMR) imaging generally allows more accurate and valid quantification of cardiac function, mass and regurgitant volumes than echocardiography. CMR imaging is not routinely performed to evaluate cardiac valves; that role is almost always in the domain of echocardiography. However, CMR imaging has much to offer in selected patients with valvular heart disease. Recent technological advancements in CMR have made evaluation of cardiac valves more reliable. We hereby report the utility of CMR in diagnosing congenital aortic valve lesions in patients who underwent CMR at our center.