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Biomedical subjects

R Parameswaran

Publications and source records attributed to R Parameswaran.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1984

Low electrocardiographic voltage in pericardial effusion.

Although low ECG voltage has been associated with pericardial effusion, its diagnostic usefulness in such patients is unclear. When we examined the relationship between the volume of pericardial effusion and low voltage in 28 patients who underwent pericardial drainage, 14 patients exhibited low voltage (sum of limb lead QRS amplitudes of 30 mm or less). In eight patients, the QRS amplitude was 5 mm or less in each of the standard leads (absolute low voltage). There was no significant correlation between the volume of the effusion and the QRS amplitude (r = -0.30). This correlation did not improve (r = -0.37) when patients with left ventricular hypertrophy were excluded. Following pericardial drainage, the QRS amplitude increased in 21 of 24 patients and decreased in three. Low voltage persisted in nine patients; the pericardium was thickened in seven of the nine. Analysis of the sensitivity and specificity revealed acceptable sensitivity only with large effusions and no left ventricular hypertrophy. Absolute low voltage appeared to be specific in the diagnosis of moderate and large effusions among patients with pericardial effusion selected for this study.

Echocardiography↗
PubMed1983

Echocardiographic quantitation of pericardial effusion.

This study was undertaken to test the validity of M-mode echocardiographic quantitation of pericardial effusion. M-mode estimate of the volume of pericardial effusion in 27 patients was compared with the actual volume of pericardial effusion removed during surgical pericardial drainage. The 16 two-dimensional echocardiographic studies in patients with small, moderate, and large pericardial effusions were reviewed to examine the distribution of pericardial fluid around the heart. Although there was good correlation between the echocardiographic estimate and the actual volume removed during surgery (r = 0.78), significant overestimation and underestimation were noted. Our findings suggest that the errors in the estimate could be attributed in part to difficulties in precise measurement of the epicardial and pericardial landmarks and in part to nonuniform distribution of pericardial fluid around the heart.

Drainage↗
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↗