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Biomedical subjects

J C Mohan

Publications and source records attributed to J C Mohan.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Ventricular tachycardia with left bundle branch block morphology in the absence of ischaemic heart disease--clinical and electrophysiological observations.

Clinical and electrophysiological features of 20 patients presenting with ventricular tachycardia (VT) of left bundle branch block (LBBB) morphology without evidence of coronary artery disease were studied. The mean age of the patients was 35.2 +/- 12 (range 15-57 years). The rate of VT varied between 140-240/min (182 +/- 80). Six (30%) patients experienced giddiness or syncope during palpitations. Structural heart disease was found in 10 (50%) of these patients, which included arrhythmogenic right ventricular dysplasia in five, submitral left ventricular (LV) aneurysm in one, anterolateral LV dyskinesis in one, dilated cardiomyopathy in one, endomyocardial fibrosis in one and nonobstructive hypertrophic cardiomyopathy in one case. Ten patients were free of structural heart disease. Electrophysiological study was done in all patients. VT with same morphology as spontaneous VT was inducible in only 14 patients. Seventeen patients were treated medically with total or partial amelioration of symptoms. In three patients, two with arrhythmogenic right ventricular dysplasia and one with structurally normal heart, who were unresponsive to drug therapy, the VT focus could be mapped in right ventricular outflow tract and successful electrical ablation was done. Thus in patients who present with VT with LBBB morphology, the heart is often structurally normal but organic disease is not uncommon, and should be carefully searched.

Adult↗
PubMedDate not supplied

Comparative evaluation of left ventricular function in sick sinus syndrome on different long-term pacing modes.

Single-chamber ventricular pacing has been implicated in the development or progression of congestive heart failure in patients with sick sinus syndrome (SSS). To define the exact role of pacing modality in causation of congestive heart failure, quantitative two-dimensional echocardiographic examination was performed in 51 consecutive patients with SSS who received an initial pacemaker from January 1979 to September 1989 and were free of any structural heart disease at the time of implant. Atrial or dual chamber pacemakers were implanted in 21 patients (Group I) and ventricular pacemakers in 30 (Group II). The two groups were matched for age, gender, paced rate, blood pressure and duration of pacing. After a mean follow-up of 64 +/- 34 months, congestive heart failure developed in one patient in group I and 3 in Group II. Patients in group II, had larger left atrium (41 +/- 5 vs 37 +/- 6 mm, p < 0.05) and left ventricular end-diastolic volume (64 +/- 18 vs 54 +/- 12 ml/m2, p < 0.01) but similar left ventricular end-systolic volume (27 +/- 12 vs 24 +/- 9 ml/m2, p = NS), ejection fraction (59 +/- 10 vs 57 +/- 8%, p = NS), left ventricular mass (84.8 +/- 31 vs 85.6 +/- 29.2 gm/m2, p = NS), meridian end-systolic wall stress (48.3 +/- 22.1 vs 49.8 +/- 25 Kdynes/cm2, p = NS) and wall stress/end-systolic volume ratio (1.27 +/- 0.94 vs 1.42 +/- 0.59, p = NS). Pacing mode does not appear to influence left ventricular systolic function in patients with SSS.

Cardiac Pacing, Artificial↗
PubMedDate not supplied

Atrial contribution to left ventricular filling in mitral stenosis: effects of balloon mitral valvuloplasty.

Doppler echocardiographic contribution of atrial systole to left ventricular filling (AC) was studied in 20 patients with mitral stenosis and compared with that obtained from 15 matched controls in a prospective study. AC in mitral stenosis as a percentage of total filling volume was 8 +/- 2.8% compared to 12.5 +/- 3.3% in control subjects (p < 0.001) and was weakly correlated to diastolic filling period (r = -0.45), mitral valve orifice resistance (r = -0.36) and heart rate (r = 0.36). An increase in mitral valve orifice area following balloon mitral valvuloplasty (0.78 +/- 0.12 to 1.72 +/- 0.4 cm2, p < 0.0001) resulted in an increase in AC to near normal values (8 +/- 2.8% to 12.5 +/- 3.8%, p < 0.001) coupled with an increase in cardiac index and a significant decrease in diastolic filling period and left atrial size. In conclusion, AC in young patients with severe mitral stenosis is decreased proportionately less than that reported in the older patients, is weakly correlated to mitral orifice resistance and normalises following a successful mitral valvuloplasty.

Adult↗
PubMedDate not supplied

Left ventricular volume overload in isolated rheumatic mitral stenosis.

Having shown the absence of chronic preload insufficiency as the mechanism of modestly depressed left ventricular ejection performance in patients with rheumatic mitral stenosis in our previous work, we sought to characterise a subset of patients with left ventricular volume overload. Echocardiographically determined ventricular load, ejection and contractile performance and left ventricular geometry were studied in 19 patients with mitral stenosis having left ventricular volume overload (end-diastolic volume > 90 ml/m2, Group I) and in 83 patients with normal volume (end-diastolic volume < 90 ml/m2, Group II). The two groups were well matched for age, gender, body size and mitral valve area. Left ventricular ejection fraction was similar in the two groups; however, the patients in Group I had higher end-diastolic volume (101 +/- 15 vs 58 +/- 18 ml/m2, p < 0.0001), end-systolic wall stress (81.7 +/- 17 vs 64 +/- 22 Kdynes/cm2, p < 0.0001), left ventricular mass (109 +/- 20 vs 82 +/- 19 gm/m2, p < 0.001) but lower relative wall thickness (26 +/- 6 vs 34 +/- 9%, p = 0.007), mass/volume ratio (1.1 +/- 0.23 vs 1.49 +/- 0.46 gm/ml, p < 0.001) and wall stress/end-systolic volume ratio (2.07 +/- 0.58 vs 2.65 +/- 0.92, p = 0.016). Of these 19 patients in Group I, seven had isolated volume overload while 12 had associated eccentric hypertrophy. Wall stress correlated well with fractional shortening in Group II (r = 0.75, p < 0.001) but not in Group I (r = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Left ventricular function and geometry in juvenile mitral stenosis.

The purpose of this study was to investigate possible differences between juvenile and adult variety of mitral stenosis (MS) with regard to left ventricular preload, afterload, contractile function and geometry by two-dimensional echocardiography. Thirty six consecutive children and adolescents with MS (Group 1, mean age +/- 1 standard deviation 16 +/- 3 yrs) were compared with an equal number of adults with MS of comparable mitral valve area (Group II, mean age 30 +/- 8 yrs). Patients with juvenile versus adult MS had similar left ventricular ejection fraction (0.57 +/- 0.09 vs 0.57 +/- 0.11, p = not significant (NS)), end-systolic wall stress (64.8 +/- 21 vs 64.3 +/- 25 Kdynes/cm2, p = NS), wall stress to end-systolic volume ratio (2.6 +/- 1.2 vs 2.71 +/- 0.9, p = NS) and mass (77 +/- 19 vs 83 +/- 26 gm/m2 p = NS) but the former had greater end diastolic volume (68 +/- 16 vs 57 +/- 18 ml/m2, p = 0.008) and sphericity index (0.62 +/- 0.19 vs 0.50 +/- 0.19, p = 0.01) and lower mass to volume ratio (1.01 +/- 0.32 vs 1.36 +/- 0.42, p (0.01). Compared to normal controls, adult patients with MS had similar end-diastolic volume (58 +/- 13 vs 57 +/- 18 ml/m2), mass (84 +/- 20 vs 83 +/- 26 gm/m2), mass to volume ratio (1.45 +/- 0.4 vs 1.36 +/- 0.42) but greater wall stress (45.6 +/- 11.7 vs 64.3 +/- 25 Kdynes/cm2, p < 0.001) and lower ejection fraction (0.66 +/- 0.07 vs 0.57 +/- 0.11, p < 0.001). Thus patients with juvenile MS have significantly altered left ventricular geometry and increased preload in response to comparably elevated afterload due to compensatory adaptive process.

Adolescent↗
PubMedDate not supplied

Long term performance of atrial leads.

Long term performance of 163 atrial leads implanted in 158 patients between July 1981 and June 1993 was evaluated. There were 122 DDD and 36 AAI units, with 125 (77%) polyurethane and 38 (23%) silicone leads. One hundred and nine (67%) unipolar and 54 (33%) bipolar leads were used. Patients were followed in the Pacemaker Clinic for 6 to 124 months (mean 50 +/- 39 months). Five patients were lost to follow up. Transient malfunction was observed in 18 cases (sensing 13, pacing 5) within the first 2 weeks. In 13 cases failure to sense subsided spontaneously and in 4 pacing malfunction could be corrected by reprogramming. Lead dislodgement occurred in 4 patients (2.5%), all within the first week. After the 1st month malfunction was uncommon. Between 1 and 12 months undersensing occurred in 4 (2.5%). In 3 cases it could be corrected by reprogramming. In the first year, reoperation was performed in 5 cases for lead related problems (3 dislodgements, 2 insulation failures). Beyond 12 months complications were as follows: failure to sense-8 (5%), failure to pace-3 (2%), insulation break -1 (0.6%). Majority of these problems could be managed by reprogramming. Reoperation was performed in 1 case with insulation break. The pacing mode had to be changed in 5 (3%) patients with dual chamber units who had loss of P wave sensing. During follow-up 98%, 98%, 96%, 95% and 83% of the leads were working satisfactorily at 1,2,3,4 and 9 years respectively. Thus atrial leads have excellent long term performance and an acceptable rate of late malfunction.

Adolescent↗
PubMedDate not supplied

Two-dimensional echocardiographic diagnosis of subaortic aneurysm.

Subaortic aneurysms are uncommon and most cases have been reported among black Africans. The present report relates to our experience with three patients having subaortic annular aneurysms, two of congenital origin and one following infective endocarditis of the aortic valve. The role of transthoracic 2- dimensional echocardiography in the diagnosis is emphasized.

Adult↗
PubMedDate not supplied

Methodological variation and agreement in assessing mitral valve orifice area by echo-Doppler methods in mitral stenosis.

Two-dimensional echocardiographic planimetry of the directly observed mitral valve orifice, pressure-half-time methods, continuity equation and the Gorlin formula are commonly used to calculate the mitral valve area. However, there have been few comparisons of the four methods. In this study, the mitral valve orifice area was determined by the above four methods using echo-Doppler data in 49 consecutive patients in sinus rhythm (mean area 0.87 to 1.26 cm2). The valve area estimated by these methods correlated well (r = 0.7 to 0.97) with excellent agreement between the continuity equation and the Gorlin formula (mean difference 0.4 cm2, r = 0.97, SEE = 0.26) and between the planimetric area and the pressure-half-time method (mean difference = 0.06 cm2, r = 0.87, SEE = 0.23). However, the limits of agreement were wide and exceeded 1 cm2 in planimetry versus the Gorlin, planimetry versus the continuity equation and pressure-half-time method versus the Gorlin formula. The standard error of estimate varied from 0.23 to 0.51 cm2 for various comparisons. Use of an empirical constant of 51.6 instead of 37.7 in the Gorlin formula provided excellent correlation between the valve area determined by the continuity equation and the modified hydraulic formula (mean difference 0.07 cm2, r = 0.95, SEE = 0.08). Estimates of the valve orifice area by any of the equations tested should be seen as a guide rather than a precise measure of actual orifice area.

Adolescent↗
PubMedDate not supplied

Age and intrinsic left ventricular myocardial contractility.

The purpose of this study was to compare the left ventricular (LV) intrinsic contractile function in normal elderly (age > or = 60 years, mean age 66 +/- 4 years) and young (age < or = 35 years, mean 27 +/- 9 years) healthy volunteers by stress-shortening and stress-length relationship using a co-variate analysis. Echocardiographically determined meridional and circumferential wall stress were plotted against LV fractional shortening, velocity of circumferential fibre shortening, end-systolic volume and diameter. LV ejection fraction, preload (denoted by end-diastolic volume) and afterload (expressed as circumferential wall stress) were similar in the two groups. Stress-shortening and stress-length relationships using the circumferential wall stress showed no difference in the two groups, although meridional wall stress was greater in the elderly population. Our results suggest that circumferential wall stress is a better method to detect intrinsic contractile abnormality in the elderly. Intrinsic LV ejection performance is within the normal range in the elderly healthy individuals.

Adult↗