Search PubMed⌕ Search

Biomedical subjects

G Natarajan

Publications and source records attributed to G Natarajan.

30 records · Page 2Linked to original sources
PubMed1982

Idiopathic long QT syndrome: association of ventricular tachycardia with alternating left and right bundle branch block.

A case of sporadic long QT syndrome with ventricular tachycardia characteristic of torsades de pointes is presented. The ECG revealed sinus rhythm with marked prolongation (less than 140%) of QT interval and alternating periods of left and right bundle branch block. The onset of ventricular tachycardia was associated with alternating left and right bundle branch block and the disappearance of bundle branch block coincided with the resolution of ventricular tachycardia. This observation suggests the possibility that heterogeneous repolarization of the bundle branch system contributed to ventricular tachycardia either alone or in combination with dispersion of refractoriness of the ventricular myocardium.

Adolescent↗
PubMed1979

Increased passive stiffness of short-term pressure-overload hypertrophied myocardium in cat.

The passive stress-strain relationship of right ventricular papillary muscles from 10 normal and 9 experimental cats with short-term pressure-overload right ventricular hypertrophy-failure was examined by plotting the logarithm of instantaneous stress (ln sigma) against the natural strain calculated as ln(l/l0) where l = instantaneous length and l0 = length at zero force. Such a stress-strain relationship was well approximated by a linear relationship. The slope K obtained from this linear relationship was higher in the hypertrophy-failure muscles (normal, 15.01 +/- 0.87 (SEM); hypertrophy-failure, 31.79 +/- 4.09; P less than 0.005). The value of the intercept, ln C was similar in the two groups (normal, -4.33 +/- 0.20; hypertrophy-failure, -4.71 +/- 0.10). This analysis indicates the the ln sigma-natural strain relationship is linear in the papillary muscle and the slope of this relationship, an index of stiffness, is increased in hypertrophy-failure muscles. Using a three-element muscle model, it is shown that increased diastolic stiffness may contribute to the decreased systolic performance.

Animals↗
PubMed1976

The relationship between prolapsing mitral leaflet syndrome and angina and normal coronary arteriograms.

Patients with a prolapsing mitral leaflet frequently have chest pain while their coronary arteriograms are normal. In this regard, these patients are similar to the group of patients with angina and normal coronary arteriograms. In the present study, clinical, electrocardiographic, cardiac hemodynamic, angiographic, and metabolic findings in 20 patients with a prolapsing mitral leaflet were compared to those of 16 patients with angina and normal coronary arteriograms. Except for the presence of mitral leaflet prolapse and systolic clicks, the findings were similar in both groups. We postulate that prolapsing mitral leaflet is probably related to two different mechanisms. In one the primary pathologic change is in the mitral valve (mainly myxomatous transformation), and the abnormalities of ventricular contraction are secondary to unloading of the heart because of a volume shift into the distended and enlarged mitral leaflets. In the other group, the primary pathologic change is in the myocardium, with secondary prolapse of the mitral valve. The myocardial abnormality itself is probably related to primary underlying myocardial disease or to arteriolar pathologic changes. The latter group has probably the same pathophysiologic abnormality as patients with angina and normal coronary arteriograms.

Adult↗
PubMed1975

Myocardial lactate metabolism during isometric hand grip test. Comparison with pacing tachycardia.

Twenty-five patients with chest pain were studied by left ventriculography and coronary arteriography. Myocardial metabolic studies were done during control state, pacing tachycardia, isometric hand grip at 30 per cent of maximum force, and combined hand grip plus pacing tachycardia. Nine patients had myocardial lactate abnormality (group 1) as evidenced by myocardial lactate production or decreased extraction (less than 10%). Though tension time index and triple product (left ventricular ejection time times HR times systolic pressure) as determinants of myocardial oxygen consumption were highest during combined hand grip plus pacing tachycardia, myocardial lactate abnormalities were most frequent during pacing tachycardia. The present study indicates that isometric hand grip even if performed during pacing tachycardia is not a sensitive test for detection of myocardial lactate abnormalities. The rising level of arterial lactate during isometric hand grip is the most likely mechanism of positive myocardial arteriovenous lactate difference.

Blood Pressure↗
PubMed1975

Comparison of ejection fraction and zonal mean velocity of myocardial fiber shortening.

To determine the extent of cardiac involvement until a diminished ejection fraction (EF) is present, zonal mean velocity of circumferential fiber shortening (Vcf) was measured from the left ventriculogram in 36 patients. The longitudinal axis (apex to mid-point of the aortic valve plane) in right anterior oblique view was divided into four equal parts by three perpeendicular chords. Zonal Vct and percent shortening along the proximal, middle and distal chords were measured. The results of this study indicate that a normal EF is frequently associated with a reduced Vct in one or even two zones. A reduced EF is generally accompanied by a diminished Vct in all three zones of the heart. In addition, a close correlation was found between zonal Vct and percent shortening. Hence the latter, which is much simpler to measure, can be instead of Vct Ejection fraction as a measure of myocardial performance is not as sensitive as Vct, especially in hearts with asynchrony of contraction.

Angiocardiography↗
PubMed1975

Myocardial metabolic studies in prolapsing mitral leaflet syndrome.

Patients with prolapsing mitral leaflet syndrome (PML) frequently have chest pain of undetermined etiology. Twenty-three patients with PML underwent cardiac hemodynamic, angiographic, and metabolic studies. The latter were performed during control spontaneous heart rate and tachycardia by right atrial pacing. Myocardial supply-demand ratio (DPTI:SPTI) was estimated from the planimetric integration of the diastolic area (diastolic pressure time index = DPTI) and systolic area (systolic pressure time index = SPTI) of the central aortic pressure. Chest pain during pacing occurred in five patients. In two patients, it was associated with ST depression typical of ischemia on the electrocardiogram. Myocardial lactate abnormalities (lactate production or less than 10% extraction) occurred in seven patients during pacing tachycardia and was present in two patients during control state. DPTI:SPTI ratio during control state was 1.22 (+/- 0.07 SE) and decreased to 0.85 (+/- 0.05 SE) during pacing tachycardia. It is concluded that the myocardial lactate abnormalities in PML, which were present in approximately 30% of the patients in the present series, are most likely due to myocardial hypoxia. Whether or not the hypoxia is secondary to "small vessel disease" is not elucidated by this study.

Adult↗
PubMedDate not supplied

Transient hyperglycemia in acute childhood illnesses: to attend or ignore?

Transient hyperglycemia occurs as a part of stress response in acute illnesses and is brought about by elevated levels of counter regulatory hormones. It is frequently encountered but the exact prevalence and implications, especially in childhood have not been studied in detail, 758 children (1 month to 6 years) with acute illness were screened for hyperglycemia; of these 36 children were found to have a glucose level of > or = 150 mg/dl at admission and were designated hyperglycemics. The overall prevalence of hyperglycemia was 4.7 per cent. The disease-wise prevalence in neurological disorders, septicemia, respiratory illnesses and diarrhoea was 7.9, 7.6, 4.2 and 3.0 per cent respectively. Family history of diabetes did not predispose towards developing transient hyperglycemia. The demographic profile (age, sex, nutrition status and disease pattern) and severity of illness (as assessed by temperature, heart rate, respiratory rate, duration of illness and hospitalization, treatment modalities required, hypoxia and acidosis) did not affect the prevalence, extent and the rate of normalization of hyperglycemia. The mortality in hyperglycemics was double (13.9%) as compared to 6.9% in non-hyperglycemics, although the difference was insignificant, statistically (O.R = 2.17, CI = 0.81-5.82, p > 0.05). It was, therefore, concluded that transient hyperglycemia occurs in 4-5% of patients with acute pediatric illnesses. However, it does not significantly correlate with the clinical profile and severity of the illness, and has no immediate prognostic significance.

Child, Preschool↗