Physiological left ventricular segmental myocardial mechanics: Multiparametric polar mapping to determine intraventricular gradients of myocardial dynamics.

OBJECTIVE: We investigated physiological systolic left ventricular (LV) myocardial mechanics and gradients to provide a database for later studies of diseased hearts. METHODS: The analyses were performed in 131 heart-healthy individuals and included seven parameters of myocardial mechanics using speckle tracking echocardiography (STE). RESULTS: Basal to apical and circumferentially significant physiological intraventricular parameter gradients of myocardial activity were determined. Global mean values and segmental ranges were peak systolic longitudinal strain -21.2 ± 3.3%, 95% confidence interval [CI] -21.8% to -20.6%), gradient (basal to apical) -16.0% to -26.7%; peak systolic longitudinal strain rate -1.24 ± 0.31%/s, 95% CI -1.29% to -1.19%/s, gradient (basal to apical) -0.91% to -1.61%/s; post-systolic index 2.6 ± 3.2%, 95% CI 3.15%-2.05%, gradient (basal/medial/apical) 7.0/1.2/2.4%; pre-systolic stretch index 1.3 ± 2.7%, 95% CI 1.77%-0.83%, gradient (basal/medial/apical) 6.5/0.2/1.3%; peak longitudinal displacement 12.2 ± 2.6 mm, 95% CI 12.6-11.8 mm, gradient (basal to apical) 21.0-3.4 mm; time-to-peak longitudinal strain 370 ± 43 ms, 95% CI 377-363 ms, gradient (basal to apical) 396-361 ms; and time-to-peak longitudinal strain rate 180 ± 47 ms, 95% CI 188-172 ms, gradient (basal to apical) 150-200 ms. CONCLUSION: This study generated a database of seven STE-derived parameters of physiological segmental and global myocardial LV mechanics. The resulting sets of three-dimensional intraventricular mappings of the entire LV provide physiological parameter gradients in baso-apical and circumferential direction by applying the 17-segment polar model. This will facilitate comparison of systolic myocardial activity of the healthy LV with diseased or otherwise altered (eg, sports) hearts.

Impact of respiration on stroke volumes in paediatric controls and in patients after Fontan procedure assessed by MR real-time phase-velocity mapping.

AIMS: Blood flow rate quantification using two-dimensional phase-contrast MRI (PC-MRI) results in averaging of flow information due to long acquisition times precluding the examination of short-term effects. The aim of this study was to determine respiration-related flow rate variations by non-electrocardiographic triggered real-time phase-contrast MRI (PC-MRI). METHODS AND RESULTS: Real-time PC-MRI was applied to study respiration-driven blood flow fluctuations in the ascending aorta (AAo), superior vena cava (SVC), and inferior vena cava (IVC) under normal and forced breathing in 33 healthy children and 10 Fontan patients. Respiration-dependent flow rates were virtually generated by dividing the respiration curve into four segments: expiration, end-expiration, inspiration, and end-inspiration. Whereas in volunteers aortic flow rate was elevated during end-expiration (5.6 ± 3.0%) and decreased during end-inspiration (-5.8 ± 3.5%) in relation to mean blood flow (P < 0.05), highest flow was detected during inspiration in SVC (10.5 ± 14.1%) and IVC (22.5 ± 12.1%) and lowest flow during expiration (-11.6 ± 13.5%, -13.2 ± 14.1%, P < 0.05). Differences were increased under forced breathing in AAo (10.4 ± 5.5%, -7.4 ± 6.5%, P < 0.05) and SVC (40.0 ± 30.3%, -30.0 ± 19.2%, P < 0.05), whereas were unchanged in IVC (16.5 ± 23.6%, -13.7 ± 21.6%, P = n.s.). Regarding patients, respiratory-dependent flow rate variability was increased and had to be related to the patient's individual quality of Fontan circulation. CONCLUSION: Real-time PC-MRI allows a physiological assessment of respiratory-related flow rate fluctuations in healthy subjects as well as in Fontan patients. Its capability for detection of short-term effects in clinical routine was demonstrated.

Percutaneous balloon mitral valvulotomy and coexisting left atrial hemangioma: case report and long-term follow-up.

Hemangiomas of the heart are extremely rare. The prognosis is quite variable, because this benign tumor may grow, involute, or stop growing; therefore, resection is usually the treatment of choice. In patients with tumors of the left atrium, percutaneous balloon mitral valvulotomy is generally contraindicated. Yet for patients with moderate-to-severe mitral valve stenosis, balloon valvulotomy is an established therapy. Herein, we present the case of a 73-year-old woman who was referred to our department in 1995 with severe mitral valve stenosis. Echocardiography showed a valve orifice area of 0.9 cm2, according to Gorlin's formula, and a mean pressure gradient of 11 mmHg. Surgical therapy was declined by the patient. There were no signs of coronary artery disease. The injection of contrast medium into the left coronary artery showed a hemangioma at the posterior wall of the left atrium. Magnetic resonance imaging and transesophageal echocardiography confirmed the diagnosis. Despite the increased risk posed by the hemangioma, we performed successful percutaneous balloon mitral valvulotomy with an Inoue balloon. We saw the patient in 2001, and again in 2008 when she was 86 years of age. She was in excellent condition, with no signs of relevant dyspnea. Magnetic resonance imaging showed the size of the hemangioma to be stable. By use of echocardiography, we were able to confirm a good long-term result of the balloon valvulotomy. In this patient, a nonsurgical approach was adequate because of the lack of growth of the hemangioma in the left atrium.

Noninvasive coronary angiography focusing on calcification: multislice computed tomography compared with magnetic resonance imaging.

OBJECTIVE: Calcification is a principal problem in noninvasive coronary angiography (CA) performed with multislice computed tomography (MSCT). Magnetic resonance imaging (MRI) supposedly neglects calcium. We compared both modalities. METHODS: Sixty-eight patients admitted for CA underwent MSCT- and MRI-based noninvasive CA the day before. Stenosis detection (>or=50%) was visually performed and validated by quantitative CA. RESULTS: The patient-based overall sensitivity, specificity, positive predictive value, and negative predictive value were 96.2%, 95.2%, 92.6%, and 97.6% for MSCT versus 69.2%, 64.3, 54.5%, 64.3%, and 77.1% for MRI, respectively. The segment-based overall results were 74.7%, 97.8%, 75.7%, and 97.6% for MSCT versus 40%, 93.8%, 37.5%, and 94.4% for MRI, respectively. Investigating the impact of coronary calcifications in the patient group with a volume score of 300 microL or greater resulted in 100%, 80%, 92.3%, and 100% for MSCT versus 70.8%, 86.7%, 89.5%, and 65% for MRI, respectively. The segment group with considerable hardening artifacts resulted in 85.3%, 83.9%, 76.3%, and 90.4% for MSCT versus 52.9%, 92.9%, 81.8%, and 76.5% for MRI, respectively. CONCLUSIONS: There are no major advantages of MRI in cases of advanced coronary calcification.

Significant obstruction of the right and left ventricular outflow tract in a patient with biventricular hypertrophic cardiomyopathy.

Echocardiography demonstrated pronounced asymmetric left ventricular (LV) hypertrophy and thickened right ventricular muscular components in a 54-year-old woman with a history of dyspnoea (NYHA III), and recurrent syncopes. Left ventricular outflow peak gradient was 80 mmHg at rest and 125 mmHg during Valsalva manoeuvre. Cardiac cine and gadolinium-enhanced T1 weighted magnetic resonance imaging (MRI) provided striking images of a right ventricular outflow tract obstruction and a markedly abnormal gadolinium uptake in the interventricular septum consistent with myocardial fibrosis. Right and left heart catherization, with simultaneous measurement of aortic and LV pressures revealed a 150 mmHg subaortic gradient and a 130 mmHg subpulmonic gradient at rest. Impediment to right ventricular (RV) outflow was due to massive hypertrophy of the crista supraventricularis with an 'hour-glass' deformity. A surgical intervention with LV septal myotomy-myectomy and RV ventriculotomy was performed successfully. Hypertrophic obstructive cardiomyopathy with significant RV and LV outflow tract obstruction is a very rare finding. Echocardiography and MRI can be used in combination for non-invasive evaluation of morphological and haemodynamic information because mechanisms of obstruction are different in each ventricle.

Uncommon intraventricular thrombus formation between the posterior mitral leaflet and the lateral left ventricular wall.

Transthoracic echocardiography demonstrated an intraventricular mass between the posterior mitral leaflet and the lateral left ventricular (LV) free wall in a 61-year-old man. Because of this uncommon localization an intracardial tumor, an endocarditis of the mitral valve or an intraventricular thrombus was suspected. Magnetic resonance imaging (MRI) ruled out an intracardial tumor and revealed a myocardial scarring of the LV free wall covered by an intraventricular thrombus by late gadolinium enhancement. MRI can distinguish subacute clots-which do not enhance after contrast material injection-from organized thrombi. The characterization of thrombi can be used to predict the risk of embolism, which is higher for subacute clots than for organized thrombi.

Ultrafast time-resolved contrast-enhanced 3D pulmonary venous cardiovascular magnetic resonance angiography using SENSE combined with CENTRA-keyhole.

PURPOSE: To evaluate the diagnostic benefit of time-resolved CENTRA-keyhole contrast-enhanced cardiovascular magnetic resonance angiography (CE-CMRA) for improving arterial-venous separation of pulmonary vessels. METHODS: Twenty-three patients (18 males; age = 58 +/- 11y) after radiofrequency pulmonary vein isolation to treat atrial fibrillation were examined using CENTRA-keyhole based multi-phase 3D CE-CMRA yielding 6 near-isotropic 3D datasets every 1.6 s (50-60 coronal partitions, 1.4 x 1.4 x 1.3 mm, SENSE-factor 3). Results were compared with conventional non-keyhole CE-CMRA (identical parameters, SENSE-factor 2). RESULTS: Data acquisition was accelerated by a speedup factor of approximately 9 compared with the reference CE-CMRA (SENSE 1.5*, keyhole 6*). No pulmonary venous stenoses were detected by either method, overall pulmonary venous diameters were 17.1 +/- 3.6 mm. Applying Bland-Altman analysis, vessel diameters differed by a mean of 0.1 mm + 2.1 mm/-2.0 mm (mean +/- 2 SD), indicating close agreement between both techniques. Interobserver variability was higher for CENTRA-keyhole (mean = 0.1 mm; mean +/- 2 SD: +2.5 mm/-2.3 mm) compared to conventional technique (0.0 mm; +1.6 mm/-1.5 mm), corresponding to a percentual deviation (mean +/- 2 SD) of the mean diameter of approximately +/- 15% (keyhole CE-CMRA) and +/- 10% (conventional CE-CMRA), respectively. Using keyhole-based time-resolved CE-CMRA, the contrast between pulmonary veins versus aorta/pulmonary artery was significantly increased (p < 0.05), which improved vessel depiction. In 12 cases, the contrast bolus arrival was delayed in one of the pulmonary veins by 1 dynamic frame (= 1.6 seconds); in 7 cases by 2 frames (= 3.2 seconds) and in 1 subject by 3 frames (= 4.8 seconds). The bolus usually appeared first in the upper right pulmonary vein whereas a delay occurred most often in the lower left pulmonary vein. CONCLUSIONS: Conventional CE-CMRA may be advantageous for accurate vessel size measures as evidenced by superior interobserver reproducibility in this study. Multi-dynamic CE-CMRA using CENTRA-keyhole with SENSE, however, allows for improved arterio-venous separation of pulmonary vessels and additional dynamical information on pulmonary venous perfusion, while maintaining high spatial resolution. Exact bolus timing is no longer needed.

Flow volume and shunt quantification in pediatric congenital heart disease by real-time magnetic resonance velocity mapping: a validation study.

BACKGROUND: Flow quantification in real time by phase-contrast MRI (PC-MRI) may provide unique hemodynamic information in congenital heart disease, but available techniques have important limitations. We sought to validate a novel real-time magnetic resonance flow sequence in children. METHODS AND RESULTS: In 14 pediatric patients (mean age 5.2+/-2.0 years) with cardiac left-to-right shunt, pulmonary (Q(p)) and aortic (Q(s)) flow rates were determined by nontriggered free-breathing real-time PC-MRI with single-shot echo-planar imaging combined with sensitivity encoding, which yielded 25 phase images per second at 2.7x2.7-mm in-plane resolution (field of view 30x34 cm2). Over a 9.5-second period that included 2 to 5 respiratory cycles, 16.6+/-2.6 subsequent stroke volumes (range 13 to 22) were acquired in each vessel. Results were compared with conventional retrospectively ECG-gated PC-MRI. Mean Q(p)/Q(s) by conventional PC-MRI was 1.91+/-0.64, and it was 1.94+/-0.68 (mean+/-SD) by real-time PC-MRI. For blood flow rate through pulmonary artery and aorta, we found differences of 2% to 3% (Bland-Altman analysis), with lower limits of agreement of -11% to -13% (mean-2 SD) and upper limits of 18% to 19% (mean+2 SD), which demonstrated good agreement between both methods. Mean difference for Q(p)/Q(s) was 1%, with limits of agreement ranging between -18% and 22% (mean+/-2 SD). High repeatability but some flow overestimation was observed in vitro (pulsatile flow phantom) with real-time PC-MRI, whereas conventional PC-MRI was accurate. Beat-to-beat stroke-volume variation was 6.1+/-2.3% in vivo and 3.7+/-0.3% in vitro. CONCLUSIONS: Beat-to-beat quantification of pulmonary and aortic flows and hence left-to-right shunt within a few seconds is reliable by nontriggered real-time PC-MRI with echo-planar imaging and sensitivity encoding. Good spatial/temporal resolution and a large field of view may render the sequence valuable for multiple applications in congenital heart disease.

Atrial septal defects in pediatric patients: noninvasive sizing with cardiovascular MR imaging.

PURPOSE: To evaluate phase-contrast magnetic resonance (MR) imaging for sizing of secundum atrial septal defects (ASDs) and inflow MR angiography for detection of associated venous anomalies in pediatric patients with inconclusive transthoracic echocardiographic (TTE) results. MATERIALS AND METHODS: Sixty-five children (mean age, 5.4 years +/- 2.7 [SD]) with ASD and inconclusive TTE results underwent phase-contrast MR imaging. Defect size and rim distances measured on MR imaging sections obtained in the ASD plane and from the defect to the venae cavae, aortic root, and atrioventricular valves were compared with transesophageal echocardiographic (TEE) findings (n = 30) during transcatheter closure or surgical measurements (n = 40) by using Bland-Altman analysis. Inflow MR angiography was compared with invasive cine angiocardiography for detection of associated venous anomalies. RESULTS: For ASD size, mean differences were less than 1 mm between MR imaging and TEE measurements (with upper and lower limits of agreement between 2.3 and -3.3 mm) and were between 1.2 and -1.6 mm between MR imaging and surgical measurements (with upper and lower limits of agreement between 4.7 and -5.2 mm). Septal rim measurements at MR imaging agreed fairly well with TEE and surgical results. Septal length was overestimated at MR imaging versus TEE (mean difference, 3.0 mm; upper and lower limits of agreement, between 8.0 and -2.8 mm), but MR imaging septal length measurements agreed with surgical results. Rim distance to coronary sinus was difficult to assess. MR imaging enabled referral of 25 of 30 patients for successful transcatheter closure; five patients were found to have too large defects after balloon sizing. Multiple ASDs and/or associated vascular anomalies in 17 of 65 patients were clearly identified at MR imaging, compared with results of TEE, surgery, and cardiac catheterization. CONCLUSION: In children with ASD and inconclusive TTE results, MR imaging can enable determination of defect size, rim distances to adjacent structures, and venous connections.