Sunil Chandy

Electrical remodelling of the left and right atria due to rheumatic mitral stenosis

AIMS To characterize the atrial remodelling in mitral stenosis (MS). METHODS AND RESULTS Twenty-four patients with severe MS undergoing commissurotomy and 24 controls were studied. Electrophysiological evaluation was performed in 12 patients in each group by positioning multi-electrode catheters in both atria to determine the following: effective refractory period (ERP) at 10 sites at 600 and 450 ms; conduction time; conduction delay at the crista terminalis (CT); and vulnerability for atrial fibrillation (AF). P-wave duration (PWD) was determined on the surface ECG. In the remaining 12 patients in each group, electroanatomic maps of both atria were created to determine conduction velocity and identify regions of low voltage and electrical silence. Patients with MS had larger left atria (LA) (P < 0.0001); prolonged PWD (P = 0.0007); prolonged ERP in both LA (P < 0.0001) and right atria (RA) (P < 0.0001); reduced conduction velocity in the LA (P = 0.009) and RA (P < 0.0001); greater number (P < 0.0001) and duration (P< 0.0001) of bipoles along the CT with delayed conduction; lower atrial voltage in the LA (P < 0.0001) and RA (P < 0.0001); and more frequent electrical scar (P = 0.001) compared with controls. Five of twelve with MS and none of the controls developed AF with extra-stimulus (P = 0.02). CONCLUSION Atrial remodelling in MS is characterized by LA enlargement, loss of myocardium, and scarring associated with widespread and site-specific conduction abnormalities and no change or an increase in ERP. These abnormalities were associated with a heightened inducibility of AF.

Reverse Remodeling of the Atria After Treatment of Chronic Stretch in Humans: Implications for the Atrial Fibrillation Substrate

OBJECTIVES The aim of this report was to study the effect of chronic stretch reversal on the electrophysiological characteristics of the atria in humans. BACKGROUND Atrial stretch is an important determinant for atrial fibrillation. Whether relief of stretch reverses the substrate predisposed to atrial fibrillation is unknown. METHODS Twenty-one patients with mitral stenosis undergoing mitral commissurotomy (MC) were studied before and after intervention. Catheters were placed at multiple sites in the right atrium (RA) and sequentially within the left atrium (LA) to determine: effective refractory period (ERP) at 10 sites (600 and 450 ms) and P-wave duration (PWD). Bi-atrial electroanatomic maps determined conduction velocity (CV) and voltage. In 14 patients, RA studies were repeated >or=6 months after MC. RESULTS Immediately after MC, there was significant increase in mitral valve area (2.1 +/- 0.2 cm(2), p < 0.0001) with decrease in LA (23 +/- 7 mm Hg to 10 +/- 4 mm Hg, p < 0.0001) and pulmonary arterial pressures (38 +/- 16 mm Hg to 27 +/- 12 mm Hg, p < 0.0001) and LA volume (75 +/- 20 ml to 52 +/- 18 ml, p < 0.0001). This was associated with reduction in PWD (139 +/- 19 ms to 135 +/- 20 ms, p = 0.047), increase in CV (LA: 1.3 +/- 0.3 mm/ms to 1.7 +/- 0.2 mm/ms, p = 0.006; and RA: 1.0 +/- 0.1 mm/ms to 1.3 +/- 0.3 mm/ms, p = 0.002) and voltage (LA: 1.7 +/- 0.6 mV to 2.5 +/- 1.0 mV, p = 0.005; and RA: 1.8 +/- 0.6 mV to 2.2 +/- 0.7 mV, p = 0.09), and no change in ERP. Late after MC, mitral valve area remained at 2.1 +/- 0.3 cm(2) (p = 0.7) but with further decrease in PWD (113 +/- 19 ms, p = 0.04) and RA ERP (at 600 ms, p < 0.0001), with increase in CV (1.0 +/- 0.1 mm/ms to 1.3 +/- 0.2 mm/ms, p = 0.006) and voltage (1.8 +/- 0.7 mV to 2.8 +/- 0.6 mV, p = 0.002). CONCLUSIONS The atrial electrophysiologic and electroanatomic abnormalities that result from chronic stretch due to MS reverses after MC. These observations suggest that the substrate predisposing to atrial arrhythmias might be reversed.

Mechanisms of cardiac perforation leading to tamponade in balloon mitral valvuloplasty

Mechanisms of cardiac perforation in 10 cases of cardiac tamponade encountered in a single-center series of 903 balloon mitral valvuloplasty procedures were elucidated by precise localization of the site of perforation at subsequent surgery. These mechanisms were perforation of the aortic root and adjacent right atrium by sliding up of the transseptal set (2), apical tears by straight-tip balloon catheters driven distally during mitral valve dilatation (3), apical perforations by guidewires introduced through catheters wedged in the apex (2), tear of the posterior right atrial wall by dilatation of the track produced by very low septal punctures (2), and right ventricular perforation by a pacing catheter (1). Multivariate analysis showed cardiac perforation to be significantly related to the total experience at the center (inversely) and to patient age (directly). Left ventricular perforation occurred exclusively in patients > 40 yr of age. Understanding these mechanisms has enabled formulation of effective strategies to prevent cardiac perforation.

Preliminary reports … works in progress: Transjugular approach to transseptal balloon mitral valvuloplasty

The feasibility of a transjugular approach to septal puncture and Inoue-balloon mitral valvuloplasty (BMV) was studied in 20 patients with severe mitral stenosis and varying degrees of anatomic atrial distortion. Left atrial entry by transjugular septal puncture was achieved without difficulty and BMV completed in all patients. In all of 16 patients who had high septal punctures, crossing the mitral valve with the Inoue-balloon was consistently simple and quick. In one patient, septal dilation after very high septal puncture led to a tear extending to the atrial free wall, resulting in cardiac tamponade requiring surgery. Another patient developed severe mitral regurgitation after BMV and required mitral valve replacement. Excellent results were obtained in 16 patients. The transjugular approach simplifies BMV procedure significantly in patients with distorted atrial anatomy and allows rapid patient mobilization. Its safety and efficacy need to be established in larger studies.

Efficacy of stem cell in improvement of left ventricular function in acute myocardial infarction - MI3 Trial

Background & objectives: Acute myocardial infarction (AMI) is characterized by irreparable and irreversible loss of cardiac myocytes. Despite major advances in the management of AMI, a large number of patients are left with reduced left ventricular ejection fraction (LVEF), which is a major determinant of short and long term morbidity and mortality. A review of 33 randomized control trials has shown varying improvement in left ventricular (LV) function in patients receiving stem cells compared to standard medical therapy. Most trials had small sample size and were underpowered. This phase III prospective, open labelled, randomized multicenteric trial was undertaken to evaluate the efficacy in improving the LVEF over a period of six months, after injecting a predefined dose of 5-10 × 108 autologous mononuclear cells (MNC) by intra-coronary route, in patients, one to three weeks post ST elevation AMI, in addition to the standard medical therapy. Methods: In this phase III prospective, multicentric trial 250 patients with AMI were included and randomized into stem cell therapy (SCT) and non SCT groups. All patients were followed up for six months. Patients with AMI having left ventricular ejection fraction (LVEF) of 20-50 per cent were included and were randomized to receive intracoronary stem cell infusion after successfully completing percutaneous coronary intervention (PCI). Results: On intention-to-treat analysis the infusion of MNCs had no positive impact on LVEF improvement of ≥ 5 per cent. The improvement in LVEF after six months was 5.17 ± 8.90 per cent in non SCT group and 4.82 ± 10.32 per cent in SCT group. The adverse effects were comparable in both the groups. On post hoc analysis it was noted that the cell dose had a positive impact when infused in the dose of ≥ 5 × 108(n=71). This benefit was noted upto three weeks post AMI. There were 38 trial deviates in the SCT group which was a limitation of the study. Interpretation & conclusions: Infusion of stem cells was found to have no benefit in ST elevation AMI. However, the procedure was safe. A possible benefit was seen when the predefined cell dose was administered which was noted upto three weeks post AMI, but this was not significant and needs confirmation by larger trials.

Optimization and audit of radiation dose during percutaneous transluminal coronary angioplasty

The percutaneous transluminal coronary angioplasty (PTCA) is one of the interventional procedures which impart high radiation doses to patients compared to the other cardiologic procedures. This study intends to audit and optimize radiation dose imparted to patients undergoing PTCA. Forty-four patients who underwent PTCA involving single or multiple stent placement guided under cardiovascular X-ray machine were included in the study. Radiation doses were measured using dose area product (DAP) meter for patients undergoing single and multiple stent placements during PTCA. A dose reduction of 27-47% was achieved using copper filters and optimal exposure parameters. The mean DAP values before optimization were 66.16 and 122.68 Gy cm(2) for single and multiple stent placement respectively. These values were 48.67 and 65.44 Gy cm(2) respectively after optimization. In the present scenario, due to the increase in the number of PTCAs performed and the associated risk from radiation, periodical audit of radiation doses for interventional procedures are recommended.

Audit of radiation dose during balloon mitral valvuloplasty procedure

Radiation doses to patients during cardiological procedures are of concern in the present day scenario. This study was intended to audit the radiation dose imparted to patients during the balloon mitral valvuloplasty (BMV) procedure. Thirty seven patients who underwent the BMV procedure performed using two dedicated cardiovascular machines were included in the study. The radiation doses imparted to patients were measured using a dose area product (DAP) meter. The mean DAP value for patients who underwent the BMV procedure from one machine was 19.16 Gy cm(2) and from the other was 21.19 Gy cm(2). Optimisation of exposure parameters and radiation doses was possible for one machine with the use of appropriate copper filters and optimised exposure parameters, and the mean DAP value after optimisation was 9.36 Gy cm(2).

Feasibility of Angioplasty and Stenting for Abdominal Aortic Lesions Adjacent to Previously Stented Visceral Artery Lesions in Patients with Takayasu Arteritis

Two young female patients with Takayasu arteritis presented with symptomatic long-segment abdominal aortic stenosis in the vicinity of previously deployed celiac and renal artery stents that projected markedly into the narrowed aortic lumen. Crushing or distortion of the visceral artery stents during aortic angioplasty was avoided by performing simultaneous or alternating balloon dilatations in the aorta and in the visceral artery stents. Consequently, the visceral artery stents remained patent and shortened longitudinally, allowing unhindered deployment of Wallstents in the adjacent aorta and abolition of a pressure gradient across the aortic lesions. Access to side branches covered by the Wallstent was obtained without difficulty, enabling the performance of balloon dilatation in multiple side branches and ostial stent deployment in a renal artery. These techniques could increase the scope of endovascular therapy in the treatment of patients with Takayasu arteritis.

Minimally Invasive Approach for Left Atrial Myxoma

A 32-year-old female with left atrial myxoma who was in New York Heart Association functional class IV, underwent a minimally invasive excision of the tumor through a right parasternal approach. Early follow-up demonstrated that this technique was effective and had the benefits of low cost, rapid recovery, decreased hospital stay, and a good cosmetic result.