Biomedical subjects

R G Pai

Publications and source records attributed to R G Pai.

At least 19 recordsLinked to original sources

PubMed2001

Prognostic implications of increased QRS duration in patients with moderate and severe left ventricular systolic dysfunction.

Survival analysis was performed on a cohort of 2,265 patients with left ventricular ejection fraction of </= 40% to investigate the effect of increased QRS duration on all-cause mortality. Presence of QRS prolongation independently predicted higher mortality in patients with left ventricular systolic dysfunction. This finding may have important prognostic and therapeutic implications in this patient population.

Aged↗

PubMed2001

Mixed aneurysmal and obstructive coronary artery disease causing acute myocardial infarction in a young woman with Takayasu's arteritis.

Takayasu's disease is a chronic inflammatory pathology of the aorta and its main branches. The present report describes a rare presentation of the disease in a young woman who presented with anterior myocardial infarction, and was subsequently found to have mixed aneurysmal and obstructive coronary artery disease involving the left anterior descending artery and its diagonal branches. Issues surrounding the management of coronary artery disease in this patient are discussed.

Acute Disease↗

PubMed2000

New insights into the progression of aortic stenosis: implications for secondary prevention.

BACKGROUND: The risk factors affecting aortic stenosis (AS) progression are not clearly defined. Insights into this may allow for its secondary prevention. METHODS AND RESULTS: We investigated predictors of AS progression in 170 consecutive patients with AS who had paired echocardiograms > or =3 months (23+/-11) apart. Various clinical, echocardiographic, and biochemical variables were related to the change in aortic valve area (AVA). The annual rate of reduction in AVA was 0.10+/-0.27 cm(2) or 7+/-18% per year. The reduction in AVA per year was significantly related to initial AVA (r = 0.46, P<0.0001), the mean aortic valve gradient (r = 0.27, P = 0.04), left ventricular (LV) outflow tract velocity (r = 0.26, P = 0.001), and LV end-diastolic diameter (r = 0.20, P = 0.04) and marginally to serum creatinine level (r = 0.15, P = 0.08). Patients with a rate of reduction in AVA faster than the mean had higher serum creatinine (P = 0.04) and calcium (P = 0.08) levels. Those with a serum cholesterol level >200 mg/dL had a rate of AVA reduction roughly twice that of those with a lower cholesterol level (P = 0.04). Stepwise multiple regression analysis identified initial AVA, current smoking, and serum calcium level as the independent predictors of amount of AVA reduction per year. CONCLUSIONS: Absolute and percentage reduction in AVA per year in those with AS is greater in those with milder degrees of stenosis and is accelerated in the presence of smoking, hypercholesterolemia, and elevated serum creatinine and calcium levels. These findings may have important implications in gaining further insights into the mechanism of AS progression and in formulating strategies to retard this process.

Aged↗

PubMed2000

Echocardiographic characterization of a rare type of coronary artery fistula draining into superior vena cava.

We describe an incidental finding of a rare type of anomalous coronary artery originating from the right coronary sinus of Valsalva and draining into the superior vena cava. This was suspected on transthoracic echocardiography but was further clarified with the use of coronary angiography and transesophageal echocardiography. Echocardiography was a major tool for delineating the origin of the fistula, its complicated course, and the drainage site.

Aged↗

PubMed2000

An unusual case of acquired ventricular septal defect as a complication of aortic valve endocarditis: echocardiographic delineation of multiple subvalvular complications in one patient.

We describe a patient with unusual echocardiographic features of prosthetic aortic valve endocarditis. Transesophageal echocardiography in this patient demonstrated a large multiloculated aortic root abscess extending to mitral-aortic intervalvular fibrosa, a high acquired ventricular septal defect, paravalvular aortic regurgitation caused by aortic valve dehiscence, and anterior mitral valve leaflet perforation.

Aged↗

PubMed1999

An integrated measure of left ventricular diastolic function based on relative rates of mitral E and A wave propagation.

BACKGROUND AND OBJECTIVES: The mitral E wave propagation inside the left ventricle is slowed in patients with abnormal left ventricular (LV) relaxation with a prolongation of its transit time to the LV outflow tract (T(e)). On the contrary, the mitral A wave propagation is faster in those with elevated LV end-diastolic stiffness, resulting in a shortening of its transit time (T(a)). We hypothesized that the T(e)/T(a) ratio may serve an integrated measure of global LV diastolic function. METHODS AND RESULTS: The T(e)/T(a) ratio was measured with Doppler echocardiography in 94 subjects: 25 normal subjects, 38 patients with LV hypertrophy (18 with secondary LV hypertrophy and 20 with hypertrophic cardiomyopathy), and 31 patients undergoing left heart catheterization for clinical indications. The T(e)/T(a) ratio was 1. 98 +/- 0.61 in the normal subjects, 3.32 +/- 0.93 in patients with secondary LV hypertrophy (P <.0001 vs normal), and 3.18 +/- 1.36 in patients with hypertrophic cardiomyopathy (P =.0003 vs normal). In the invasive group the T(e)/T(a) ratio (range 0.56 to 3.60) correlated significantly with Tau (r = 0.76, P <.0001), peak negative dP/dt (r = -0.46, P =.01), the LV late diastolic stiffness index (r = 0.57, P =.0013), LV pre-A wave pressure (r = 0.46, P =. 0096), LV end-diastolic pressure (r = 0.58, P =.0007), and the amount of LV pressure rise with atrial systole (r = 0.52, P =.0032) but not with the heart rate. Tau and LV stiffness were its sole determinants by stepwise multiple regression (R = 0.82). CONCLUSIONS: The ratio of mitral E and A wave transit times inside the LV (T(e)/T(a) ratio) is closely related to LV relaxation, its late diastolic stiffness, and filling pressures and gives valuable insights into LV diastolic performance.

Cardiomyopathy, Hypertrophic↗

PubMed1999

QT dispersion as a noninvasive predictor of inducible ventricular tachycardia.

The QT dispersion (QTD) on the surface electrocardiogram is a noninvasive marker of heterogeneity of ventricular repolarization. An increased QTD has been associated with spontaneous ventricular arrhythmias. We investigated the relationship of QTD to inducible reentrant sustained ventricular tachycardia (VT) in 66 patients who underwent programmed electrical stimulation. Thirty-three patients had inducible VT and 33 had noninducible VT with up to three extra stimuli. The QTD was significantly longer in patients with inducible VT (79+/-30 ms) compared with those in whom VT was noninducible (50+/-20 ms, P < .0001). QTD of > or =70 ms had a sensitivity of 67%, a specificity of 94%, a positive predictive value of 92%, and a negative predictive value of 74% for inducible VT. We conclude that QTD is an easily measurable electrocardiographic index that is increased in patients with inducible VT, and a QTD of > or =70 ms is highly predictive of VT inducibility.

Adult↗

PubMed1998

Hemodynamic basis of mitral E transmission in the left ventricular cavity and its relation to the left ventricular relaxation process.

Mitral E-wave transit time to the left ventricular outflow tract was measured as an E-Er interval in 30 subjects undergoing cardiac catheterization. The E-Er interval (range 30 to 190 ms) correlated with left ventricular peak negative dP/dt (r = -0.62, p = 0.0003) and tau (r = 0.74, p <0.0001) but not with left ventricular minimum, pre-A-wave, or end-diastolic pressures. We conclude that the E-Er interval is an easily obtainable Doppler measurement that reflects the left ventricular relaxation process.

Blood Flow Velocity↗

PubMed1998

Rates of left ventricular isovolumic pressure rise and fall from the aortic regurgitation velocity signal: description of the method and validation in human beings.

BACKGROUND: Aortic regurgitation results from a pressure gradient across the aortic valve during left ventricular (LV) isovolumic relaxation, LV filling, and isovolumic contraction periods. Assuming the applicability of the simplified Bernoulli equation to this pressure-flow relation and constancy of aortic pressure during LV isovolumic relaxation and contraction periods, one can theoretically obtain estimates of the rates of LV isovolumic pressure fall and rise (deltaP/delta t) from the aortic regurgitation (AR) velocity signal. METHODS AND RESULTS: Mitral regurgitation (MR) and AR signals were recorded by using the continuous wave Doppler technique in 26 patients with combined mitral and aortic regurgitant lesions. The LV negative deltaP/delta t was obtained by dividing the time taken for the AR velocity to rise from 1 m/sec to 2.5 m/sec into 21 mm Hg, which is the estimated LV pressure drop between these points. In a similar fashion, the LV positive deltaP/delta t was obtained between 2.5 m/sec and 1 m/sec of the fast decelerating portion of the AR signal. The LV negative deltaP/delta t by the AR method ranged from 420 to 3500 mm Hg/sec and correlated well with that obtained by the MR method obtained in a blinded fashion (r = 0.95, p < 0.0001). The mean (SD) difference between the two methods was 30 (129) mm Hg/sec. Similarly, the LV positive deltaP/delta t by the AR method (range 420 to 2625 mm Hg/sec) correlated closely with that obtained by the MR method (r = 0.93, p < 0.0001), with the mean (SD) difference between the two methods being 38 (138) mm Hg/sec. CONCLUSIONS: Preliminary data presented in this study indicate the feasibility of obtaining a reliable estimate of LV positive and negative deltaP/delta t from the AR velocity profile. Thus the examination of the AR signal may give valuable insights into both LV systolic and diastolic functions.

Aortic Valve Insufficiency↗

PubMed1998

Effect of dobutamine stress on left ventricular systolic and diastolic functions in patients with moderate to severe left ventricular dysfunction.

Dobutamine stress echocardiography (DSE) is increasingly used in patients with moderate and severe left ventricular (LV) dysfunction. However, its effect on central and peripheral hemodynamics and LV function in this patient population is not known. This study investigates the effect of dobutamine stress on LV systolic and diastolic performance and peripheral hemodynamics in 177 consecutive patients undergoing DSE. Sixty-five patients with an LV ejection fraction (EF) of < or =40% were compared with 112 patients with an EF of >40%. Compared with those with EF > 40%, patients with EF < or =40% had a faster heart rate(76 +/- 13 vs 70 +/- 13 bpm, p < 0.001), lower systolic blood pressure (127 +/- 18 vs 133 +/- 20 mm Hg, p < 0.05), lower stroke volume (60 +/- 20 vs 74 +/- 36, p = 0.01), longer LV isovolumic relaxation time (118 +/- 37 vs 108 +/- 25 msec, p < 0.05) and larger LV end-diastolic (57 +/- 9.6 vs 49 +/- 7 mm, p < 0.0001) and end-systolic (46 +/- 10 vs 32 +/- 7.9 mm, p < 0.0001) diameters. They also had a lesser increment in cardiac output (1.5 +/- 1.6 vs 3.2 +/- 4.8 L/min, p = 0.02), a smaller reduction of systolic LV size (-5.3 +/- 4.1 vs -7.0 +/- 4.3 mm, p < 0.05) and a lower propensity to LV cavity obliteration with dobutamine infusion. In conclusion, patients with an EF < or =40% have lower baseline stroke volume, systolic blood pressure, higher heart rate, and longer LV isovolumic relaxation time. They also have a smaller increase in cardiac output, a smaller reduction of LV size, and a lower propensity to LV cavity obliteration with dobutamine stress.

Adrenergic beta-Agonists↗

PubMed1998

Amplitudes, durations, and timings of apically directed left ventricular myocardial velocities: I. Their normal pattern and coupling to ventricular filling and ejection.

BACKGROUND: The left ventricular (LV) major axis shortening is an important determinant of its global function. But unlike the LV minor axis dynamics, the long-axis dynamics have not been well characterized. We investigated the amplitudes, durations, and timings of LV long-axis myocardial velocities and related them to LV filling and ejection in normal healthy volunteers. METHODS AND RESULTS: Myocardial velocities from the basal, mid, and distal portions of the four LV walls were recorded from the apical window with spectral Doppler tissue imaging in 20 normal individuals. The timings, amplitudes, and durations were measured and compared both longitudinally and circumferentially. These were also related to mitral inflow and LV ejection. Analysis of the recordings indicated that there were three principal myocardial velocities: apically directed systolic velocity and atrially directed early and late diastolic velocities. The LV posterior wall had the highest shortening velocity and the amount of shortening. The lateral wall had the greatest amplitude of early diastolic lengthening velocity, amount of lengthening, and early to late lengthening velocity and integral ratios, probably indicating most favorable early diastolic properties. There was a striking synchrony in the myocardial velocities circumferentially. The myocardial velocities dropped progressively as the sampling site was moved distally and the LV apex was practically stationary. Although the onsets of the velocity profiles were simultaneous in the meridional orientation, their durations were shorter distally. All myocardial velocities preceded the corresponding blood flow velocities. They also ended before the corresponding blood flow velocities, this being more pronounced in the distal myocardial segments, indicating the presence of inertial factors responsible for the terminal portions of mitral and aortic flows. CONCLUSIONS: Recording of apically directed myocardial velocities gives valuable insights into the regional myocardial function. These velocities show significant regional variations in healthy normal individuals. It is speculated that analysis of regional myocardial velocities may have a role in the diagnosis of early myocardial disease.

Adult↗

PubMed1998

Amplitudes, durations, and timings of apically directed left ventricular myocardial velocities: II. Systolic and diastolic asynchrony in patients with left ventricular hypertrophy.

BACKGROUND: Regional myocardial dysfunction may be the earliest manifestation of myocardial disease and can occur in the absence of abnormalities of global left ventricular (LV) function. The LV long-axis function, which is mainly due to subendocardial muscle fibers, may become abnormal in the presence of normal short-axis function. This study investigates the temporal and spatial characteristics of the LV long-axis function in patients with secondary LV hypertrophy in the presence of normal systolic function. METHODS AND RESULTS: LV long-axis myocardial velocities were recorded in 18 patients with LV hypertrophy and preserved regional and global systolic function with Doppler tissue imaging. Apically directed myocardial velocities were recorded from the basal, mid, and apical segments of the four LV walls, and their amplitudes, timings, and durations were measured. The abnormalities uncovered by the analysis of regional myocardial velocities included (1) asynchrony in the onset of myocardial contraction circumferentially, (2) presence of postejection LV shortening, (3) asynchrony in the onset of early myocardial lengthening circumferentially, (4) reduced early myocardial lengthening velocity, (5) reduced early to late myocardial lengthening velocity and extents circumferentially, and (6) lack of variation in the basal myocardial velocities circumferentially in contrast to normal individuals. CONCLUSIONS: Patients with secondary LV hypertrophy with preserved regional and global systolic performance have distinct abnormalities in the timings and amplitudes of apically directed myocardial velocities. These abnormalities may explain some of the changes in LV global diastolic behavior and may also serve as markers of early regional myocardial dysfunction.

Aged↗

PubMed1998

Left ventricular cavity obliteration during dobutamine stress echocardiography is associated with female sex and left ventricular size and function.

We investigated 568 consecutive patients undergoing dobutamine stress echocardiography to elucidate the mechanism of left ventricular (LV) obliteration. Baseline clinical and echocardiographic variables were related to dobutamine-induced LV cavity obliteration defined as approximation of LV endocardium associated with an intracavitary flow acceleration of at least 2 m/s in the absence of a distal residual cavity. The LV cavity obliteration was observed in 89 (16%) of the 568 patients and was more frequent in women and those with smaller LV dimensions, increased LV wall thickness, and higher resting ejection fractions. Despite similar peak stress levels, the cavity obliterators were less likely to have chest pain and detectable stress-induced wall motion abnormalities. We conclude that LV cavity obliteration during dobutamine stress is common and is associated with female sex, smaller LV size, presence of LV hypertrophy, and higher LV ejection fraction. Despite similar stress levels, chest pain and reversible wall motion abnormalities are observed less frequently in patients with cavity obliteration, raising the possibility of lower prevalence of coronary artery disease or masking of ischemia in this patient population.

Aged↗

PubMed1998

Effect of gender and left ventricular dysfunction on the incidence of hypotension induced by dobutamine stress echocardiography.

BACKGROUND: Of patients who undergo dobutamine stress echocardiography (DSE), 14% to 38% experience hypotension that sometimes requires termination of the test before an adequate cardiac work-load is reached. The mechanisms of hypotension reportedly are related to peripheral vasodilation, a decrease in cardiac output, and left ventricular (LV) cavity obliteration. DSE is performed increasingly in women and in patients with LV dysfunction. However, the impact of gender and LV dysfunction on DSE-induced hypotension has not been elucidated. METHODS AND RESULTS: Clinical, hemodynamic, and echocardiographic characteristics were studied in 412 patients undergoing DSE, 82 patients with an LV ejection fraction of 40% or less, and 147 women. Hypotension, defined as a decrease in systolic blood pressure of at least 20 mm Hg, occurred in 117 (28%) patients. Hypotension was more common in women than men (36% vs 24%, P = .01). Hypotension was also more common in older adults (P = .004), persons taking diuretics (P = .025) or angiotensin-converting enzyme inhibitors (P = .01), and persons with higher baseline blood pressures (P < .0001). Hypotension was not related to the use of beta blockers, calcium channel blockers, digoxin, nitrates, LV dimensions, or ejection fraction. CONCLUSIONS: The incidence of DSE-induced hypotension is related to gender but not to the level of LV systolic function. It also is associated significantly with higher age, and use of angiotensin-converting enzyme inhibitors or diuretics.

Adrenergic beta-Agonists↗

PubMed1998

Mitral E wave propagation as an index of left ventricular diastolic function. I: Its hydrodynamic basis.

BACKGROUND AND AIMS OF THE STUDY: Left ventricular (LV) diastolic dysfunction is an early sign of myocardial disease and an important determinant of symptoms and prognosis in patients with various cardiovascular disorders. Evidence suggests the presence and clinical importance of abnormal LV diastolic function in patients with valvular heart diseases, but it is difficult to measure non-invasively. Mitral E wave propagation inside the left ventricle studied by analysis of digitized color M-mode and pulsed wave Doppler technique is a promising technique for the evaluation of LV relaxation. However, the precise mechanism of its transmission is not clearly defined. Understanding the precise hydrodynamic basis of E wave propagation would be helpful for its meaningful application to the evaluation of LV diastolic performance. This study investigates the hydrodynamic determinants of mitral E wave propagation in an in vitro setting. METHODS AND RESULTS: Thirty-one sets of experiments were conducted in a linear, pulsatile left ventricle model with varying operative diastolic characteristics. The rate of transmission of the onset of the E wave was strongly related to operative LV diastolic stiffness (r = 0.93, p < 0.0001), and weakly to mean left atrial (LA) pressure (r = 0.46, p < 0.01), heart rate (r = 0.57, p < 0.01) and stroke volume (r = -0.58, p < 0.01) through an effect on operative LV diastolic stiffness. The peak of the E wave transmission was influenced not only by operative LV diastolic stiffness (r = 0.87, p < 0.0001), but also by the mean LA pressure, heart rate and stroke volume, in an independent fashion. CONCLUSIONS: The rate of transmission of the onset of the mitral E wave is determined solely by operative LV diastolic stiffness, whereas that of the peak is also affected by the mean LA pressure, heart rate and stroke volume. Analysis of mitral E wave propagation in patients with valvular heart disease may give clinically useful insights into LV diastolic function.

Diastole↗

PubMed1998

Mitral E wave propagation to the left ventricular outflow tract. II: Evaluation of left ventricular filling pressures and diastolic stiffness from an analysis of their amplitude and duration in a modeled human left ventricle.

BACKGROUND AND AIMS OF THE STUDY: The rate of mitral E wave propagation inside the left ventricle is related to the rate of left ventricular (LV) relaxation. However, the relationship of the amplitude and duration of the transmitted E wave (EOT wave) to the LV diastolic properties is not known. The hypothesis that the amplitude and duration of the EOT wave is related to the LV filling pressures and its diastolic properties was tested in an in vitro setting of modeled left ventricle. METHODS AND RESULTS: Thirty-one sets of experiments were conducted in a pulsatile left ventricle model with varying LV filling pressures and operative diastolic characteristics. The EOT wave amplitude correlated with the mean left atrial pressure (r = 0.86, p < 0.0001), LV end-diastolic pressure (r = 0.89, p < 0.0001) and average LV diastolic stiffness (r = 0.38, p = 0.05). The EOT wave duration was not related to any of these measures of LV diastolic function, but E wave duration and EOT/E wave duration ratio were significantly related to LV diastolic stiffness (r = -0.88 and 0.71 respectively, both p < 0.0001). Multivariate equations were developed from the amplitudes and durations of E and EOT waves to predict left atrial and LV end-diastolic pressures and LV diastolic stiffness with a high degree of confidence (cumulative R values 0.92, 0.97 and 0.92 respectively). CONCLUSIONS: These in vitro findings indicate that LV filling pressures and operative diastolic stiffness may potentially be derived from the amplitudes and durations of diastolic flow waves at the mitral inflow and LV outflow. However, these findings need to be confirmed in in vivo settings.

Diastole↗

PubMed1997

Value of QT dispersion in the interpretation of exercise stress test in women.

BACKGROUND: Exercise testing in women is associated with a high incidence of false-positive ECG changes and should be combined with an imaging study. The QT dispersion (QTD), recorded as the difference between maximum and minimum QT intervals on a 12-lead ECG, is sensitive to myocardial ischemia and may improve the accuracy of exercise testing in women. METHODS AND RESULTS: Exercise ECGs were analyzed in 64 women who had undergone exercise ECG and coronary angiography for clinical indications: 20 patients with normal exercise stress test and nonsignificant (< or = 50% diameter narrowing of a major epicardial coronary artery) coronary artery disease (CAD) on angiography (true-negative; TN group), 20 patients with positive exercise stress tests (> or = 1 mm ST-segment depression or reversible perfusion defects) and significant CAD (true-positive; TP group), and 24 patients with positive exercise stress tests but no significant CAD (false-positive; FP group). The exercise QTD was 45+/-15 ms in TN, 80+/-23 ms in TP (P<.0001 versus TP), and 41+/-14 ms in FP (P=NS versus TN and <.0001 versus TP) groups. A stress QTD of > 60 ms had a sensitivity of 70% and specificity of 95% for the diagnosis of significant CAD compared with 55% (P<.05) and 63% (P<.01), respectively, for > or = 1 mm ST-segment depression during stress. When QTD of > 60 ms was added to ST-segment depression as a condition for positive test, the specificity increased to 100%. CONCLUSIONS: Exercise QTD is an easily measurable ECG variable that significantly increases the accuracy of exercise testing in women.

Adult↗

PubMed1997

Clinical and echocardiographic correlates of mitral E-wave transmission inside the left ventricle: potential insights into left ventricular diastolic function.

The mitral inflow wave is initially directed to the left ventricular apex and then turns around facing the left ventricular outflow tract. The E and A waves are transmitted to the left ventricular outflow tract where they are registered as Er and Ar waves, respectively. We hypothesized that the E-wave transit time to the left ventricular outflow tract recorded as the E-Er interval may depend on left ventricular early diastolic performance such as relaxation. This hypothesis was tested in clinical settings known to have abnormal left ventricular relaxation. Mitral E and left ventricular outflow tract Er waves were recorded with pulsed wave Doppler technique in 63 subjects: 25 healthy subjects, 18 patients with secondary left ventricular hypertrophy, and 20 patients with hypertrophic cardiomyopathy. The E-Er interval was measured from the onset of E wave to the onset of Er wave timed to the R wave of the electrocardiogram. The E-Er interval ranged from 45 to 300 msec: 96 +/- 28 msec in the controls, 127 +/- 46 msec in patients with left ventricular hypertrophy (p = 0.0091 versus controls), and 179 +/- 57 msec in patients with hypertrophic cardiomyopathy (p < 0.0001 versus controls). It correlated with left ventricular free wall thickness (r = 0.42, p = 0.0006), thickness of the ventricular septum (r = 0.43, p = 0.0004), left ventricular end-diastolic diameter (r = -0.38, p = 0.0022), left ventricular end-systolic diameter (r = -0.55, p < 0.0001), left ventricular isovolumic relaxation time (r = 0.39, p = 0.0063), RR interval (r = 0.28, p = 0.045), mitral E/A velocity ratio (r = -0.33, p = 0.010), and E-wave deceleration time (r = 0.38, p < 0.0044) but not with age. Multivariate analysis with all the previously mentioned variables and the group the patient belonged to as the dichotomous variable showed that the grouping variable was the sole independent determinant of the E-Er interval (multiple r = 0.74). The E-Er interval is an easily measurable Doppler parameter which is increased in left ventricular hypertrophy and hypertrophic cardiomyopathy. It is related to left ventricular wall thickness, left ventricular isovolumic relaxation time, mitral E/A velocity ratio, and E-wave deceleration time and may provide useful insight into left ventricular early diastolic performance-possibly the relaxation process.

Aged↗