Electricity and the heart.

Understanding of cardiac rhythm requires application of physical principles governing electricity. Over a period of more than 100 years, application of the knowledge of electric current led to the gradual evolution of electrocardiogram, pacemaker, defibrillator, and ultimately electrophysiology. The discovery of electrocardiogram (ECG) by Einthoven in 1902 and that of pacing by Zoll in 1952 were two landmarks in this field.

Rupture of the sinus of valsalva into the pulmonary artery.

Congenital aneurysms of the sinus of Valsalva are rare lesions that can rupture into any cardiac chamber, due to the central position of the aortic root. Rupture into the pulmonary artery, however, is very rare. We encountered an 18-year-old girl with rupture of the right coronary sinus into the pulmonary artery. During surgical correction, the girl was also found to have a small outlet ventricular septal defect, which was obscured by multiple hypertrophied septal trabeculae in the right ventricular outflow tract.

Long-term performance of single-pass physiological pacing.

BACKGROUND: Single-pass physiological pacing has several advantages over dual-lead physiological pacing. The present study evaluated the long-term performance of single-pass pacing using the overlapping biphasic impulse stimulation technique. METHODS AND RESULTS: A total of 30 patients with single-pass VDD pacing and 8 patients with single-pass DDDC pacing were followed up for 1 year by basal and magnet electrocardiograms and real-time telemetry. All the patients showed satisfactory atrial sensing and pacing capture threshold. The atrial sensing thresholds at implant and at 1 month, 3 months, 6 months and 12 months of follow-up were 2.5+/-0.67 mV, 1.6+/-0.6 mV, 1.1+/-0.5 mV, 1.0+/-0.5 mV and 1.0+/-0.04 mV, respectively. The corresponding values for atrial pacing threshold at a pulse wave of 0.5 ms were 2.5+/-1.0 V, 4.4+/-0.9 V, 3.8+/-1.2 V, 3.6+/-1.4 V and 3.8+/-1.4 V. Of the patients with DDDC pacing, 88% showed stable pacing capture in the supine position, 75% in the upright position and 62% in both positions. Diaphragmatic contraction was seen in 25% of cases with DDDC pacing. No such event was seen in patients with VDD pacing. CONCLUSIONS: Single-pass pacing is safe, technically easy and cheap as compared to dual-lead systems. However, it would be prudent to recommend DDDC pacing in patients who require predominantly VDD pacing and only occasionally atrial pacing, as the latter showed a low percentage of stable atrial pacing capture in both upright and supine positions as well as a significant percentage of diaphragmatic contraction.

The newer unconventional indications of permanent pacemakers.

In recent years, the indications for permanent pacemakers have expanded. The interest has focussed on hypertrophic cardiomyopathy, dilated cardiomyopathy and a new entity called hypertensive hypertrophy with cavity obliteration (HHCO). Pacemaker therapy is establishing itself for the prevention of atrial fibrillation. Pacing for neurocardiogenic syncope with newer pacing mode has encouraging datas. Pacemaker for long QT syndrome, after cardiac transplant and for haemodynamic improvement in occasional cases of first degree atrio-ventricular block is getting attention. The AHA and ACC guidelines updated in 1998 for implantation of cardiac pacemakers, now include several of these newer indications.

Venous obstruction after permanent pacing.

In a 10-year prospective study of 6,256 patients (5,812 males, 444 females) with permanent pacemaker, 25 had presented with features of venous obstruction such as pain, swelling or dilated superficial veins of face, upper limb(s) or upper chest wall without congestive heart failure. When subjected to contrast venography, 22 (0.35%) of the cases demonstrated subclavian and/or superior vena cava thrombotic/fibrotic obstruction. Each patient had non-progressive dilated veins over upper chest wall which developed after an average period of six months of implantation and none had embolic events or cephalad propagation of thrombus. Nine patients had subclavian, eight superior vena cava and five had both the vein obstructions. Seven patients of venous obstruction were treated with heparin followed by oral anticoagulants and three patients with oral anticoagulants alone. Three of seven patients got relief of obstruction with combined therapy group (heparin followed by oral anticoagulants) only. Two patients with superior vena cava obstruction needed epicardial pacing during subsequent lead revision. Therefore, before revision of permanent pacemaker leads in patients with signs of venous obstruction, venography can be useful to assess the obstruction and to determine the route of new lead insertion.

Dilated cardiomyopathy in non-specific aortoarteritis.

Out of 195 cases of Takayasu's arteritis who presented in our institute between January 1988 and December 1997, 12 (5.58%) had dilated cardiomyopathy. Age of these patients ranged from 10 to 30 years (17.25 +/- 5.30 years) and male-female ratio was 1:11. All the cases had cardiovascular system features (dyspnoea, oedema, palpitation, angina, etc. but without hypertension), three had central nervous system features (headache, vomiting, convulsion etc.) and all had general systemic features like weight loss, malaise, fever, arthralgia etc. Electrocardiography, chest X-ray and echocardiographic findings were consistent with dilated cardiomyopathy. Haemodynamic findings showed raised left ventricular end-diastolic pressure and pulmonary capillary wedge pressure in all; raised pulmonary artery pressure, pulmonary vascular resistance, right ventricular pressure and right atrial pressure in 6, 6, 4 and 2 cases, respectively; reduced left ventricular peak systolic pressure in 10 cases but central aortic pressure and systemic vascular resistance in all the cases were within normal limits. Angiography showed type I, II and III involvement in 7 (majority), 3 and 2 cases, respectively. Coronary and pulmonary angiography were normal and left ventricular angiography showed poor left ventricular systolic function in all the cases. Histopathological study (on 3 autopsy cases) showed non-specific inflammation of myocardium with lymphocyte/mononuclear cell infiltration and normal coronary vessels. So, dilated cardiomyopathy in Takayasu's arteritis is not rare, though not much reported, and can influence the prognosis of aortoarteritis cases.

Hypertension, insulin resistance and atherosclerosis.

Hypertension, in a sizable number of patients, though not all, is associated with and possibly caused by insulin resistance. The later is also associated with a cluster of other risk factors of atherosclerosis and coronary artery disease, namely, obesity, glucose intolerance with or without overt diabetes, hypercholesterolaemia, low high density lipoprotein (HDL), hypertriglyceridaemia, hypercoagulability, etc. Currently, all these disorders are together called insulin resistance syndrome (IRS) as insulin resistance is the common denominator of these abnormalities. The clinicians should identify the individuals who are at risk or already have manifestations of IRS, especially among the hypertensives, and direct their antihypertensive therapy to improve insulin sensitivity and to minimise atherosclerotic coronary heart disease.

Coronary artery lesions in Takayasu's arteritis--clinical and angiographic study.

Two hundred and twenty five patients of Takayasu's arteritis were studied over 13 years. Male:Female ratio was 1:7. Mean age of the study population was 19 +/- 4 years. Of these 225 patients, 75 patients had symptoms and/or signs of cardiac involvement and these patients were subjected to coronary angiography. Significant coronary artery occlusion (i.e. more than 50% narrowing of luminal diameter) was present in 9 patients. Incidence of coronary artery lesions in Takayasu's arteritis is 12% in this study. The proximal segments of coronary arteries were involved while the distal segments were spared. Out of 34 patients with angina pectoris, only 3 patients had significant coronary arterial narrowing.

Aortoarteritis involving supra-aortic trunks: a profile of six cases.

Six patients (2 male, 4 female; age range 24 to 36 years) with aortoarteritis involving the supra-aortic trunks were investigated and surgically managed by bypass graft with either preclotted dacron or polytetrafluoroethylene (PTFE) in an urban institute. There has been no mortality and post-operative functional recovery has been satisfactory in all the cases.

Hypertension in the young in eastern India.

Three hundred and forty-one young hypertensives in the age group of 18-30 years were evaluated over a 7-year period. Essential hypertension constituted the single largest group (35.8%). Renal pathology was the most common cause of secondary hypertension (26.4%). Congenital coarctation of the aorta and endocrine causes accounted for 14.1 percent and 3.2 percent cases of secondary hypertension, respectively. A strikingly high incidence of nonspecific aortoarteritis (20.1%) was a distinguishing feature amongst secondary causes. Aortoarteritis was the commonest cause of renal artery stenosis. Renal angioplasty was performed in 11 patients with refractory hypertension. Forty percent of the patients achieved post-angioplasty control of blood pressure without drugs; in 25 percent, the blood pressure became easier to control. Restenosis was detected in 4 cases over 18-24 months of follow-up.

Reuse of pacemaker.

Implantation of a permanent pacemaker is an expensive proposition for the poor patients of our country. Many patients on permanent pacemaker die prematurely due to diseases or conditions not related to pacemaker function. The purpose of this study was to reuse these pacemakers after thorough cleansing and proper sterilisation in other suitable patients and compare the efficiency of the reused pacemakers with that of newly implanted ones. Between April 1979 and April 1992, 642 patients implanted with reused pacemakers were studied. The study population consisted of patients ranging in age from 15-85 years and included patients of both sexes (M:F = 4:1). The mean period of follow-up was 7.5 +/- 5.6 years. Removal and reimplantation of the pulse generators was carried out after obtaining the State Government's approval, informed consent of the donors, relatives and recipients. The functional status of the pulse generators was tested by a "pacing system analyser". The clinical indications for reuse were chronic complete heart block, symptomatic bifascicular heart block, sick sinus syndrome and chronic complete heart block with congestive heart failure, in decreasing order of frequency. In terms of morbidity and mortality, the efficacy of reused pacemakers was highly comparable with that of newly implanted ones. The infection rate in cases of reuse from dead patients was comparable to that in cases of new implantation. However, pacemakers reused in the same patient showed a high rate of infection. With the aid of newer generations of antimicrobials, infection when matched with efficacy and economy (of reuse) does not seem to be a major factor against pacemaker reuse.

A study of inferior vena cava obstruction.

Inferior Vena Cava obstruction as a major cause of hepatic venous outflow block is not so common. A prospective study of 20 cases gave us an opportunity to device a management protocol for this disorder. Out of 20 cases we had studied, 12 had only inferior Vena Cava obstruction while rest of the 8 cases had both hepatic vein and IVC blockade. However, balloon cavoplasty showed remarkable results with substantial clinical and haemodynamic improvement in cases with isolated IVC obstruction. Therefore, we suggest that patients with IVC obstruction should be actively managed with Vena-cavography followed by cavoplasty. Treatment of Hepatic venous obstruction along with IVC obstruction is controversial; bypass shunt is usually required and long term follow-up studies are required to establish safety and efficacy.

Cardiac tumours: an observational study.

We studied 38 patients with cardiac tumours. Of these, 30 had primary cardiac tumours while the rest had secondary tumours. The commonest manifestations in patients with primary tumours were exertional breathlessness (23), fever (9), mitral diastolic murmur (15), loud pulmonary component of the second heart sound (16), and mitral systolic murmur (21). Left atrial myxoma was the commonest diagnosis (24) followed by left ventricular leiomyoma (2), right atrial myxoma (2, one with RA and RV both), RV myxoma (1), and left ventricular haemangioma (1). The commonest modes of presentation of secondary cardiac tumours were atrial extrasystoles (5) and pericardial friction rub (4). Histopathological reports revealed bronchogenic carcinoma (4), breast carcinoma (2), seminoma of the testis (1) and lymphoma (1). The unexpectedly low number of secondary cardiac tumours in this series is attributed to the lack of routine autopsy studies in our institute.