R. Parameswaran

The complementary role of magnetic resonance imaging, Doppler echocardiography, and computed tomography in the diagnosis of dissecting thoracic aneurysms.

Non-ECG gated MRI was compared with 2DE and/or CT scans in 10 patients with dissecting aneurysms proven by angiography and/or surgery. Patient ages ranged from 48 to 85 years (mean 69.6). Six had DeBakey type I dissections and four had DeBakey type III dissections. MRI was diagnostic for aortic dissection in nine cases and suggestive in the tenth. 2DE was diagnostic in six out of nine patients, suggestive in two patients, and nondiagnostic in one patient. CT was diagnostic in the three cases in which it was employed. MRI demonstrated a dilated ascending aorta with thickened walls in all type I dissections as well as an intimal flap and slow flow in the false channel in four patients. In the other two patients with type I dissection, MRI detected the intimal flap in the descending aorta but not in the ascending aorta, whereas 2DE revealed the ascending aortic intimal flap in both of these patients and CT showed it in one of them. In the type III dissections, MRI demonstrated a thickened wall and thrombus in the lumen in all four cases, and the intimal flap in three out of the four. 2DE excluded ascending aortic involvement in all three type III dissections. Six other patients with fusiform dilated ascending aortas had no evidence of dissection by MRI, 2DE, and aortography. Thus, non-ECG gated MRI alone or in combination with 2DE and/or CT is useful in the diagnosis of dissecting thoracic aneurysm and in assessing the extent of the dissection. In addition, the differentiation of dissecting aneurysms of the aorta from fusiform dilatation of the aorta is made possible by these noninvasive techniques.

Peripheral embolization during thrombolytic therapy for left atrial thrombus

Abstract Recent studies have focused attention on the effects of anticoagulants1 and thrombolytic agents in the treatment of left ventricular thrombi.2 We report the use of thrombolytic therapy in a patient with a large left atrial thrombus.

Left Ventricular Thrombi in Association with Normal Left Ventricular Wall Motion in Patients with Malignancy

mias. However, the only patient with complex and frequent arrhythmias also had a significant prolonged PEP index (147 ms). Despite the small number of patients examined, our impression, based on the results obtained, is that the arrhythmogenic role of alcohol if not acutely ingested) is relatively unimportant. Our study confirms the finding that chronic alcoholics have an incidence of arrhythmias similar to normal subjects.

Sinus bradycardia due to lidocaine: Clinical-electrophysiologic correlations

Summary Two patients in whom profound sinus bradycardia resulted from the use of lidocaine are described. In one patient, complete AV block also occurred in association with sinus bradycardia. While congestive failure and the associated hepatic insufficiency may have contributed to excessive blood levels of lidocaine in one patient, these factors were not evident in the other. The occurrence of sinoatrial block in isolated rabbit heart preparations during exposure to lidocaine suggests that a similar mechanism may be responsible for instances of “sinus bradycardia” and “sinus arrest” in patients with heart disease. The development of sinoatrial block in conjunction with suppression of latent pacemakers in the AV junction and the ventricles may result in particularly dangerous arrhythmias and should be borne in mind when using lidocaine in patients with heart disease.

Aberrant conduction due to retrograde activation of the right bundle branch

Summary An example of aberrant conduction of sinus beats initiated by a single premature atrial beat is shown. A detailed analysis of the electrocardiogram reveals the aberration to be due to repetitive retrograde activation of the right bundle branch giving rise to asynchronous recovery of the bundle branches.

Electrical activity in the left bundle branch

Summary Electrical potentials from the left bundle branch were recorded through an electrode catheter positioned in the left ventricle at a level just below the aortic valve. Electrograms obtained by this technique are described and examples illustrated. The interval from the onset of the P waves to the activation of the left bundle branch was variable, and was related to the PR interval. The interval from activation of the left bundle branch to the beginning of the QRS complex remained constant in spite of changes in the heart rate. In one patient with intermittent left bundle branch block, the level of conduction delay was noted to be in the proximal left bundle where one Wenckebach cycle was recorded. In another patient with corrected transposition and first degree A-V block, the region of conduction delay was shown to be distal to the A-V node.

Sinus and A-V nodal dysfunction following myocardial infarction.

A patient in whom syncopal episodes occurred following an inferior myocardial infarction is described. Electrocardiographic monitoring revealed periods of profound sinus bradycardia and AV block during syncope. In addition, transient spontaneous prolongations of the PR interval due to AV nodal delay and episodes of atrial fibrillation also occurred. Sinus node recovery time following atrial overdrive was within normal limits. Symptoms disappeared following the insertion of a permanent, demand pacemaker. The onset of symptoms following myocardial infarction suggests that dysfunction of the sino-atrial and AV nodes may have been the result of ischemic damage during the infarction.