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R Parameswaran

Publications and source records attributed to R Parameswaran.

At least 19 recordsLinked to original sources
PubMed1986

Echocardiographic analysis of left ventricular filling in isolated pure chronic aortic regurgitation.

Left ventricular (LV) diastolic filling was assessed using digitized M-mode echocardiography in 12 patients with aortic regurgitation (AR) and in 12 normal subjects. Ten patients with AR were asymptomatic and 2 patients had congestive heart failure. LV chamber dimensions, fractional shortening and the rate of change of LV dimensions during systole and diastole were determined. In addition, the timing of the rate of change of LV dimensions in diastole (peak dD/dt, 50% peak dD/dt and 20% peak dD/dt) was also measured. Patients with AR had a significant reduction in dD/dt (12.2 +/- 3.5 cm/s in patients with AR vs 15.9 +/- 1.9 cm/s in normal subjects, p less than 0.01) and a delay in the timing of peak dD/dt (160 +/- 35.2 ms in patients with AR vs 86 +/- 17.6 ms in normal subjects, p less than 0.01) from the minimum LV dimension. These diastolic abnormalities were present in patients with symptomatic as well as those with asymptomatic AR, occurred even when the fractional shortening and peak systolic emptying rate (peak -dD/dt) were normal, and showed no correlation with the calculated LV mass (r = 0.14). The delay in the diastolic filling velocities (peak dD/dt, 50% and 20% peak dD/dt) was associated with a decreased rate of change of LV dimension in diastole, suggesting delayed early LV filling. These findings indicate an abnormality of LV diastolic filling in patients with symptomatic as well as asymptomatic AR and suggest that diastolic abnormalities may precede echocardiographic indexes of systolic LV dysfunction.

Adolescent↗
PubMed1986

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.

Aged↗
PubMed1986

Magnetic resonance imaging and two-dimensional echocardiography. Alternative approach to aortography in diagnosis of aortic dissecting aneurysm.

Unrecognized acute dissection of the aorta requires rapid and accurate diagnosis for appropriate management. The "gold standard" for diagnosis has been invasive angiography, but this diagnosis can be achieved noninvasively via two-dimensional echocardiography, computed tomographic scanning, and magnetic resonance imaging. Two patients are described in whom echocardiography and magnetic resonance imaging were complementary diagnostic aids. The advantages and disadvantages of echocardiography, computed tomographic scanning, magnetic resonance imaging, and aortography in aortic dissection are discussed. It is anticipated that a combination of noninvasive diagnostic aids will eliminate the need for invasive angiography in many instances in the future.

Aged↗
PubMed1985

The uses of two-dimensional Doppler echocardiographic techniques preoperatively and postoperatively in a ventricular septal defect caused by penetrating trauma.

Doppler echocardiography was used to determine the site and size of a ventricular septal defect in a patient with a penetrating wound of the heart. Additional physiological measurements by Doppler study, including pulmonary artery pressure and degree of left-to-right shunting, were helpful in deciding on surgical closure of the defect as the definitive therapy in this patient. Associated intracardiac defects (e.g., mitral or tricuspid regurgitation) can be excluded by Doppler echocardiography.

Adult↗
PubMed1979

The posterior thoracic approach in echocardiography.

Echocardiograms were recorded using a left posterior thoracic approach in 17 patients with left pleural effusion. Comparison of these records with those obtained using the conventional technique in the same patients revealed that the left posterior thoracic approach yielded records of adequate quality in all patients. The mitral valve, the left ventricle, and the posterior pericardium were well defined. In 10 patients in whom pericardial effusion was also p;esent, the posterior approach facilitated clear separation of the pleural and pericardial effusions. A major limitation of the posterior technique appears to be inability to record the aortic root, the aortic valve, and the left atrium.

Echocardiography↗
PubMed1976

Sinus node dysfunction in acute myocardial infarction.

The frequency, clinical course, and prognosis of sinus node dysfunction in 431 patients with acute myocardial infarction admitted to the coronary care unit were studied. Sinus node dysfunction occurred in 20 patients. In 13, the principal manifestation consisted of severe sinus bradycardia. In the remaining 7, periods of bradycardia alternating with episodes of supraventricular tachycardia were noted. Though several of the patients with sinus bradycardia required intravenous atropine or temporary pacing, normal sinus rhythm returned in virtually all during follow-up. The clinical course of patients with both bradycardia and tachycardia was less benign, during the acute phase and during follow-up; 5 of the 6 survivors required continued antiarrhythmic therapy or permanent pacing. The differences in the clinical course between these two groups of patients may reflect distinct underlying pathological changes. The findings in this study suggest that in contrast to sinus bradycardia, the occurrence of bradycardia-tachycardia syndrome during the acute phase of myocardial infarction may have important prognostic implications.

Acute Disease↗
PubMed1976

Spontaneous variations in atrioventricular conduction in pre-excitation.

Atrial pacing in a patient with a Wolff-Parkinson-White syndrome pattern showed unusual variability in AV nodal conduction time. Changes in the AV nodal conduction time occurred predominantly at paced rates in excess of 100/min and consisted of abrupt or gradual decreases in the AH interval. Such decreases resulted in unexpected normalization of the QRS pattern. In addition, pacing also revealed evidence of block in the accessory pathway. Such changes in atrioventricular conduction may account for the known variability of the QRS pattern in patients with the WPW syndrome. Further, they may also explain the benign clinical course in this patient.

Adult↗
PubMed1975

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.

Aged↗