End-systolic and end-diastolic left atrial volume assessment by two-dimensional echocardiography: a comparison study with magnetic resonance imaging.

BACKGROUND: The left atrial volume (LAV) is an important indicator of the severity of certain diseases, and measuring LAV through the cardiac cycle may enable the evaluation of various left atrium (LA) functional parameters. The results of two-dimensional (2D) echocardiographic LAV measurement methods vary, and no technique is accepted as being optimal. OBJECTIVE: This study compared the accuracy of end-systolic and end-diastolic LAV measurements by 2D echocardiography with those obtained by magnetic resonance imaging (MRI). METHODS: Fifty consecutive patients who underwent both echocardiography and MRI due to clinical reasons with nonselective cardiac disease were studied. LAVs by 2D echocardiography were obtained with the prolate ellipsoid (PE), biplane area-length (AL), and modified Simpson's (MS) methods. RESULTS: End-systolic and end-diastolic LAVs calculated by each method correlated significantly with MRI results (P < 0.0001). The prolate ellipsoid method provided LAVs that most correlated with MRI results, and the biplane area-length and modified Simpson's methods provided LAVs with small mean differences (<5 ml) compared to MRI results. CONCLUSION: All three methods of 2D echocardiographic LAV measurement provide valuable LAV data, suggesting the possibility of evaluating various LA functional parameters.

Comparison of delayed myocardial enhancement in the early and late phase after contrast injection: is it possible to reduce the examination time for myocardial viability study?

OBJECTIVES: We studied whether we can obtain a myocardial viability study immediately after contrast injection to reduce the whole cardiac MR examination time. MATERIALS AND METHODS: We examined 36 patients with cardiovascular abnormality on comprehensive cardiac MRI. T1-weighted images with inversion recovery (IR) were obtained 5 min after stress perfusion with 0.05 mmol/kg of gadodiamide and 15 min after the resting perfusion with the same dose. (The latter images were obtained 25 min after the initial administration.) We evaluated the existence, the number of sectors, and the degree of enhancement at each time. The contrast ratio was also calculated. The number of the enhanced sectors and the contrast ratio were statistically compared using Student's t test. RESULTS: All 17 cases of delayed myocardial enhancement at 25 min after contrast injection showed some enhancement at 5 min after contrast injection. However, the number of enhanced sectors was larger at 25 min after the initial injection in 11 cases, and it was statistically significant (P=.017). The degree of enhancement was stronger at 25 min in 14 cases. However, the contrast ratio at 5 and 25 min after contrast injection was not significantly different (P=.245). CONCLUSION: Myocardial viability study immediately after contrast injection is too early to evaluate the extent of myocardial injury.

Efficacy of spectral presaturation of inversion recovery in evaluating delayed myocardial enhancement.

OBJECTIVE: Delayed myocardial enhancement is caused by a variety of cardiovascular diseases. The extent of the enhanced area has been examined by the inversion recovery (IR) method, whereby at the inversion time (TI), normal myocardium shows a low signal intensity. In this sequence, as pericardial fat shows a very high intensity, a delayed enhancement just below the pericardium may be indistinct. To improve the accuracy of delayed myocardial enhancement, we employed the spectral presaturation of inversion recovery (SPIR) method. MATERIALS AND METHODS: Thirty-five patients with symptoms of cardiovascular disease aged between 36 and 80 years old (mean age, 62 years old) were investigated. Thirty were men and five were women. Inversion recovery and SPIR images were obtained 25 min after initial administration of a gadolinium-based contrast material. Each TI, when the signal intensity of the normal myocardium was null, was determined by images obtained at serial different TIs. A radiologist and a cardiologist examined each image by a consensus reading. The extent of myocardial enhancement was described as none, subendocardial, transmural and a random pattern in each case. Images were ranked over three levels and were based on whether myocardial enhancement could be easily detected or whether the contour of the myocardium was visualized precisely. Student's t-test was conducted to compare the quality of two sequences in all patients and in 22 patients who showed delayed myocardial enhancement. RESULTS: The imaging quality in evaluating delayed myocardial enhancement in all patients was superior with IR compared with SPIR, although it was not statistically significant. The imaging quality in the patients with delayed myocardial enhancement was similar between SPIR and IR. SPIR was superior to the IR sequence in two of the four patients who exhibited transmural enhancement. CONCLUSION: SPIR exhibited equivalent image quality to IR in evaluating delayed myocardial enhancement. As it has the potential advantage in patients with rich adipose tissue surrounding the myocardium, it can be an alternative sequence to evaluate myocardial viability.

Amlodipine improves vascular function in patients with moderate to severe hypertension.

The long-term effects of amlodipine, a calcium channel blocker, were examined in patients with moderate to severe hypertension. Eighteen never-treated patients with moderate to severe essential hypertension (49 +/- 8 years) were studied. In all patients, forearm blood flow (FBF) was measured by plethysmography before and 6 months after amlodipine treatment. Endothelium-nondependent and endothelium-dependent vasodilations were assessed by intrabrachial infusion of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. FBF modification by vitamin C, an oxygen radical scavenger, was also assessed under ACh infusion. The results were compared with those of 13 normal subjects. Blood pressure was significantly lowered (from 176 +/- 17/97 +/- 13 to 144 +/- 12/82 +/- 10 mm Hg) after treatment (P < 0.01). Forearm vascular resistance was increased in the hypertensive patients before treatment; however, it was normalized after treatment during SNP infusion and was improved during ACh infusion. Since vitamin C improved FBF under ACh infusion both before and after the amlodipine treatment, it is suggested that the production of free radicals was not canceled by amlodipine. The analysis of heart rate variability showed that amlodipine does not activate sympathetic nerve function. Therefore, amlodipine is effective in lowering blood pressure associated with the improvement of vascular function, and is suggested to be an effective antihypertensive agent for patients with moderate to severe hypertension.

Noninvasive diagnosis of partial atrial standstill using magnetocardiograms.

A 59-year-old woman with partial atrial standstill was studied using magnetocardiograms (MCGs), which revealed through QRS-T subtraction and time-frequency analysis that there was a high-frequency (6 Hz) magnetic source at the low atrial septum. MCGs are useful for noninvasively evaluating the clinical course of patients with atrial fibrillation.

Magnesium sulphate infusion suppresses the cardiac release of noradrenaline during a handgrip stress test.

BACKGROUND: Magnesium has several important cardiovascular effects, but its effect on cardiac sympathetic efferent neuron activity has not been clarified. OBJECTIVES: To examine the effect of magnesium sulphate infusion on cardiac sympathetic efferent postganglionic neuronal liberation of noradrenaline. PATIENTS AND METHODS: Twenty-two patients who underwent cardiac catheterization were randomly allocated to the control group or the magnesium group. Plasma noradrenaline and adrenaline concentrations in the aorta and the coronary sinus were measured. Noradrenaline or adrenaline release from the heart was calculated by dividing the difference in noradrenaline or adrenaline concentration between the aorta and the coronary sinus by that of the aorta. After baseline blood sampling, the control patients and the patients in the magnesium group received intravenous infusion of saline or magnesium sulphate (10 mmol). All patients were then subjected to 3 min of handgrip exercise stress test to augment sympathetic efferent neuronal activity, and the blood sampling was repeated. RESULTS: Although blood pressure was increased by the handgrip stress test, there were no differences in heart rate and blood pressure between the two groups, both at baseline and during the handgrip stress test. The plasma noradrenaline and adrenaline concentrations and noradrenaline or adrenaline release from the heart did not differ between the two groups in the baseline condition. However, the handgrip stress increased plasma noradrenaline concentrations and the cardiac noradrenaline release was increased in the control group, whereas the cardiac noradrenaline release was not increased by the handgrip stress in the magnesium group (P<0.02). CONCLUSIONS: These data indicate that magnesium sulphate infusion suppresses the release of catecholamines by the heart, which is an indirect index of sympathetic efferent neuronal activity.