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Biomedical subjects

Rakesh K Pai

Publications and source records attributed to Rakesh K Pai.

At least 19 recordsLinked to original sources
PubMed2006

The effects of rate and irregularity on sympathetic nerve activity in human subjects.

BACKGROUND: We have recently shown that atrial fibrillation is associated with an increase in sympathetic nerve activity (SNA) compared with sinus rhythm. It remains unclear, however, whether these findings are true at various rates and whether the magnitude of sympathoexcitation is related to the degree of irregularity. OBJECTIVE: To determine the role of irregularity in mediating the SNA changes at various pacing rates. Univariate analysis showed that as the irregularity increased, SBP increased (r = 0.44, P < .001) but that MAP and DBP did not change significantly. METHODS: Using custom-made software, atrioventricular sequential pacing with predetermined rates (100, 120, and 140 bpm) and irregularities (standard deviation = 0%, 5%, 15%, and 25% of mean cycle length) was performed in 23 patients referred for electrophysiologic evaluation. Pacing at each rate/irregularity was performed for 2 minutes, with 2 minutes of recovery in between. Systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MAP), central venous pressure (CVP), and SNA were measured at baseline and during pacing. RESULTS: Univariate analysis showed that as the irregularity increased, SBP increased (r = 0.44, P < .001 but that MAP and DBP did not change significantly. A significant correlation was found between the pacing irregularity and SNA, with greater sympathoexcitation noted at greater degrees of irregularity (r = 0.2, P = .04). A five-variable linear model using DBP, MAP, CVP, and degree of pacing irregularity to predict SNA was highly statistically significant (r = 0.46, P < .001). After controlling for hemodynamic changes, for every 1% increase in irregularity, there was a 6.1% increase in SNA. CONCLUSION: We have shown that greater degrees of irregularity cause greater sympathoexcitation and that the effects of irregular pacing on SNA are independent of the hemodynamic changes.

Atrial Fibrillation↗
PubMed2006

Case report: Radiofrequency catheter ablation of typical atrial flutter and the atrioventricular junction via the superior vena caval approach in a patient with a congenital absence of an inferior vena cava.

The absence of an inferior vena cava is a rare congenital condition often without clinical significance. Alternative venous approaches are often needed to treat these patients. We report a case of successful ablation of both isthmus dependent flutter and the AV junction using the superior vena cava in a patient with an inferior vena cava anomaly.

Atrial Flutter↗
PubMed2006

Klebsiella pneumoniae: a rare cause of device-associated endocarditis.

Intravascular infections involving implanted pacemakers and defibrillators are being seen with increasing frequency. This report describes a case of intravascular infection of an implanted defibrillator with Klebsiella pneumoniae, an unusual pathogen for pacemaker or defibrillator infection.

Endocarditis, Bacterial↗
PubMed2006

The magnitude of sinus cycle length change during ventricular tachycardia is predictive of successful antitachycardia pacing.

BACKGROUND: Despite the wide use of antitachycardia pacing (ATP) in patients with implantable cardioverter defibrillators (ICDs), predictors of ATP success remain poorly understood. We hypothesize that the degree of sympathoexcitation, as measured by the sinus cycle length (SCL) shortening during ventricular tachycardia (VT), is a predictor of ATP success. METHODS AND RESULTS: The charts of 462 patients with dual-chamber ICDs were reviewed. A total of 88 events in 26 patients met the inclusion criteria and were analyzed. The mean SCL during the 4 seconds preceding the VT onset (SCL-baseline), and during the 4 seconds prior to ATP delivery (SCL-VT) was measured. The percent shortening in SCL was calculated as ((SCL-baseline) - (SCL-VT))/(SCL-baseline) x 100. Patients were classified into the ATP-success and ATP-failure groups depending on the VT(s) response to ATP. Using a t-test analogue for clustered data, patients in the ATP-success group exhibited a greater shortening in SCL when compared with the ATP-Failure group (5.8% compared to 4.7%, P = 0.007). The successful ATP events displayed an average SCL shortening of 6.0% compared to 1.8% in the unsuccessful ATP events (P = 0.029). When the events were analyzed, the sensitivity and specificity of a shortening in SCL of >10% in predicting ATP success were 0.29 and 1. CONCLUSION: We have shown that the SCL change during VT, a marker of the autonomic changes that accompany a tachycardia, is useful in predicting ATP success. Our findings suggest that analysis of the SCL during VT might play a role in future programming of ATP in patients with ICDs.

Cardiac Pacing, Artificial↗
PubMed2004

The use of the Doppler pulmonary artery velocity time integral to optimize placement of a ventricular pacing lead in a patient with Ebstein's anomaly.

Ebstein's anomaly is a rare congenital heart defect. Patients with severe symptomatic tricuspid regurgitation requiring surgical correction often have conduction system disease. We present a case of a 14 year-old girl with Ebstein's malformation and bioprosthetic tricuspid valve who required permanent pacing for symptomatic bradycardia. The placement of the right ventricular pacing lead was facilitated by the use of the Doppler pulmonary artery velocity time integral as a surrogate for stroke volume. This case demonstrates the importance of site-specific pacing and the utility of Doppler echocardiography to optimize lead placement and cardiac performance in patients with Ebstein's anomaly and advanced conduction system disease.

Adolescent↗
PubMed2004

Pacemaker lead infection secondary to Haemophilus parainfluenzae.

Cardiac device infections are a rare complication of pacing and defibrillator therapy. The number of implanted devices will likely continue to rise with increasing implantation of the cardioverter defibrillator and cardiac resynchronization devices. This report describes a case of an uncommon pathogen for device-associated endocarditis.

Adult↗
PubMedDate not supplied

AIDS associated with severe cor pulmonale and large pericardial effusion with cardiac tamponade.

Cardiac involvement in patients with advanced HIV/AIDS is common, including pericardial effusion and pulmonary hypertension. Although there is an increased incidence of pericardial effusion in patients with AIDS, most are small and asymptomatic. The presence of a pericardial effusion and/or pulmonary hypertension is associated with shortened survival. We present a case of a 43-year-old man with AIDS and advanced cardiovascular involvement who developed severe cor pulmonale and a large pericardial effusion with cardiac tamponade.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

The importance of the evolution of ST-T wave changes for differentiating acute pericarditis from myocardial ischemia.

A 28-year-old, moderately obese man with dyslipidemia (low-density lipoprotein 163 mg/dL, high-density lipoprotein 33 mg/dL), hypertension, active tobacco use (1 pack per day), and a family history for premature coronary artery disease (CAD) initially presented with burning, nonexertional chest discomfort exacerbated by deep inspiration. His initial electrocardiogram (ECG; Fig. 1A) was interpreted as pericarditis because of the diffuse mild ST-segment elevation and PR-segment depression. An echocardiogram demonstrated normal left ventricular systolic function and a trivial pericardial effusion. He was treated with nonsteroidal antiinflammatories and his symptoms resolved. Follow-up ECG performed the next morning (Fig. 1B) demonstrated sinus rhythm, persistent mild ST elevation, and biphasic T waves in leads V3-V4 as well as in leads III and aVF. Four months later, the patient returned with similar symptoms of chest discomfort and was admitted with the diagnosis of unstable angina. The admission ECG was unremarkable showing no persistent PR or ST-T abnormalities. He was ruled out for myocardial infarction by serial enzymes. An exercise myocardial perfusion imaging study was obtained. The patient exercised for 7 minutes 33 seconds on a standard Bruce protocol, obtained 9.4 METs, and reached 69% of maximum predicted heart rate. His exercise ECG revealed up to 2.5 mm of ST-segment elevation in leads V3-V5 accompanied by chest discomfort. The patient's chest pain resolved with cessation of exercise and 1 sublingual nitroglycerin. The ECG returned to baseline within 3 minutes of recovery. He was referred for coronary angiography and was found to have a proximal left anterior descending (LAD) stenosis and underwent percutaneous coronary intervention with stenting. He was discharged home on postprocedure day 3.

Acute Disease↗