Search PubMed⌕ Search

Biomedical subjects

J D Carroll

Publications and source records attributed to J D Carroll.

At least 55 records · Page 3Linked to original sources
PubMed1992

Factors influencing immediate results, complications, and short-term follow-up status after Inoue balloon mitral valvotomy: a North American multicenter study.

Clinical trials with the Inoue mitral valvotomy balloon have recently begun in the United States. We assessed the effects of 17 demographic, echocardiographic, procedural, and hemodynamic variables on the immediate results, complications, and short-term follow-up of 200 patients in 15 centers undergoing valvotomy with this device. The study population had a mean age +/- SD of 53 +/- 15 years, and the total echocardiographic score was 7.2 +/- 2.4. Valvotomy was technically successful in 96.5% of procedures and increased the mean mitral valve area from 1.0 +/- 0.3 to 1.8 +/- 0.7 cm2 (p less than 0.001); 72% had an increase in valve area greater than or equal to 50%, and 67% had a final area greater than or equal to 1.5 cm2. Major procedural complications included cardiac tamponade during transseptal puncture (1.0%), systemic embolism (1.5%), and severe mitral regurgitation (2.4%); there were no procedural deaths and one hospital death. Multivariate analysis identified the absence of prior surgical commissurotomy and younger age as significant predictors of the gain in mitral valve area, but the correlation coefficients were low. Although the absence of subvalvular disease on echocardiograms was a predictor of a final valve area greater than or equal to 1.5 cm2, the total echocardiographic score did not correlate well with the immediate outcome (r = 0.01, p = NS). No variable was identified as predictive of restenosis, which occurred according to echocardiographic criteria in 14 of 66 (21%) patients evaluated 6 months after valvotomy. Good hemodynamic results with valvotomy were achieved in the majority of patients with low complication rates by many investigators with the use of the Inoue balloon device.(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon Occlusion↗
PubMed1992

Effect of valve deformity on results and mitral regurgitation after Inoue balloon commissurotomy.

BACKGROUND: The effect of valve deformity and patient age adversely affect the results of percutaneous transvenous mitral commissurotomy (PTMC) with conventional balloons. METHODS AND RESULTS: These factors were characterized after PTMC with the Inoue balloon. The increases in mitral valve area and mitral regurgitation after the procedure were evaluated comparing echocardiographic score of 8 or less versus more than 8, age of less than 60 versus age of 60 years or more, and age of less than 70 versus age of 70 years or more. One hundred sixty-two patients (mean age, 52 +/- 14 years) were studied. For the entire group, mitral valve area increased from 1.0 to 1.8 cm2 (p less than 0.001). Valve area increased from 1.0 +/- 0.3 to 1.8 +/- 0.6 cm2 in patients with echocardiographic score of 8 or less (n = 102) and from 1.0 +/- 0.3 to 1.7 +/- 0.5 cm2 with echocardiographic score of more than 8 (n = 44). Patients less than 60 years old (n = 104) had increases in valve area from 1.0 +/- 0.3 to 1.8 +/- 0.6 cm2 versus 1.0 +/- 0.4 to 1.8 +/- 0.6 cm2 for those 60 years old or older (n = 50) (p = NS). There was no significant difference in resultant valve area when the age division was increased to less than 70 versus 70 years or more. Similarly, the percentage of patients with 2+ or greater increase in mitral regurgitation was not different for those with higher than for those with lower echocardiographic scores (4% versus 12%, p = NS), age of less than 60 versus age of 60 years or more (10% versus 10%, p = NS), or age of less than 70 versus age of 70 or more years (9% versus 18%, p = NS). Valve replacement for mitral regurgitation was performed in four patients (one emergency), all with echocardiographic scores of less than 8. CONCLUSIONS: Age and extent of valve deformity do not have significant effects on acute results of PTMC using the Inoue balloon. Unique balloon geometry or the controlled, stepwise balloon sizing may explain these acceptable acute results in patients with more-deformed valves.

Adult↗
PubMed1992

Sex-associated differences in left ventricular function in aortic stenosis of the elderly.

BACKGROUND: In aortic stenosis, the response of the left ventricle to pressure overload varies from compensated hypertrophy to overt heart failure. The determinants of left ventricular adaptation are poorly understood. METHODS AND RESULTS: Left ventricular function was compared to assess the role of sex in 34 women and 29 men 60 years or older with both hemodynamic and echocardiographic data characteristic of severe aortic stenosis and no important coronary artery disease. Despite a similar degree of left ventricular outflow obstruction in women versus men (aortic valve area 0.54 +/- 0.20 versus 0.59 +/- 0.19 cm2, NS), the left ventricle of women had a greater fractional shortening (37 +/- 12 versus 25 +/- 12%, p = 0.001), achieved a smaller end-systolic chamber size (1.82 +/- 0.64 versus 2.17 +/- 0.65 cm/m2, p = 0.04), and generated more pressure (210 +/- 35 versus 182 +/- 29 mm Hg, p = 0.001) with a greater maximum positive dP/dt (2.153 +/- 794 versus 1,595 +/- 384 mm Hg/sec, p = 0.02). The men had a lower cardiac index (2.12 +/- 0.59 versus 2.49 +/- 0.63 l/min/m2, p = 0.02), higher mean pulmonary artery pressure (35 +/- 13 versus 27 +/- 10 mm Hg, p = 0.01), and shorter ejection period (340 +/- 40 versus 370 +/- 40 msec, p = 0.02). Women and men were equally symptomatic. Supernormal left ventricular ejection performance was present in 41% of the women and only 14% of the men (p = 0.002). This subgroup of women had a small, thick-walled chamber (end-diastolic radius to thickness ratio, 1.58 +/- 0.52 versus 2.45 +/- 0.51 in control women, p = 0.01) with low end-systolic wall stress. Subnormal ejection performance was present in 64% of the men and only 18% of the women (p = 0.002). This subgroup of men had an increased chamber size and high end-systolic wall stress compared with control men. Greater left ventricular mass was present in men compared with women (211 +/- 55 versus 179 +/- 55 g/m2, p = 0.03). CONCLUSIONS: Sex is a factor in left ventricular adaptation to valvular aortic stenosis in adults 60 years or older.

Aged↗
PubMed1992

Power-afterload relation in the failing human ventricle.

Animal studies have shown that the power output of the left ventricle is related to afterload by a bell-shaped curve. Furthermore, the normal ventricle operates at the maximum power point, whereas the diseased ventricle operates off the maximum power point because of increased afterload. We studied this relation in eight patients with dilated cardiomyopathy. A high-fidelity catheter with micromanometer pressure and electromagnetic velocity transducers was used to measure blood pressure and flow velocity in the ascending aorta. The latter was converted into volumetric flow by calibrating with the simultaneously determined thermodilution cardiac output. Ventricular power was calculated by dividing the integral of the aortic blood pressure-flow product by the duration of the cardiac cycle. Intravenous nitroprusside was used to alter afterload and the power-afterload relation was obtained by plotting power against mean aortic blood pressure. In all patients, as blood pressure was lowered initially, the power output of the left ventricle increased. As the dose of nitroprusside was increased further, the total power either plateaued or actually decreased. The averaged power and the mean blood pressure at control were 1.00 +/- 0.62 W and 92 +/- 9.3 mm Hg, respectively. The averaged maximum increase in power with nitroprusside was 22%, to 1.22 +/- 0.73 W, and this occurred at a mean pressure of 80 +/- 8.8 mm Hg. This study showed that the power-afterload relation in the human ventricle has a maximum power point at some intermediate level of afterload, similar to that found in animal studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Changes in valvular resistance, power dissipation and myocardial reserve with aortic valvuloplasty.

Balloon aortic valvuloplasty results in small changes in valve area with great symptomatic improvement in some patients, while others have little relief with greater increases in valve area. Alternative indices to valve area may help explain this clinical discrepancy. A calculation of valve area does not provide a means of assessing the load imposed by a stenotic valve, while the complementary index valve resistance, defined as the quotient of mean pressure difference divided by flow, allows many other hemodynamic calculations and may provide an additional measure of the hemodynamic importance of valvular obstructions. To assess the value of these calculations, we studied hemodynamic changes in thirty elderly patients undergoing valvuloplasty for aortic stenosis. The valve area, as calculated by the Gorlin formula, increased by an average 67% (0.59 cm2 to 0.95 cm2), while hemodynamic resistance decreased by an average 52% (453 to 207 dyne.sec.cm5). The values of resistance were used to predict pressure gradients and work loads at different cardiac outputs. The increase in myocardial reserve with valvuloplasty was calculated as the increase in cardiac output that could be achieved at the pre-valvuloplasty value of either total ventricular pressure or ventricular work. These calculations assumed that valvular resistance did not change with cardiac output and that peripheral resistance varied inversely to cardiac output so as to maintain a constant aortic (systemic) pressure. The increase in myocardial reserve was 18% when ventricular work rate was the limiting factor, and 103% when pressure was limiting. The increase in reserve may be closer to the higher value since the myocardial work rate is probably not limited by myocardial energy in the absence of coronary artery disease. Four patients who did not do well clinically were characterized by small increases in reserve, either because of inadequate dilatation of the valve or because the original stenosis was not severe. Valve resistance, myocardial reserve, and ventricular work may be calculated using standard hemodynamic measurements. In conjunction with aortic valve area, these indices provide significant complimentary information and may further elucidate the hemodynamic consequences of valvular obstruction.

Aged↗
PubMed1991

Valve deformity and balloon mechanics in percutaneous transvenous mitral commissurotomy.

Percutaneous transvenous mitral commissurotomy (PTMC) using balloon catheters has emerged as an alternative therapeutic modality for patients with mitral stenosis. When used initially in the United States, a single balloon, designed for peripheral arterial angioplasty, was passed across the intraatrial septum for mitral dilatation. The results were less than ideal, with resultant valve areas between 1.0 and 1.5 cm2. Double balloon dilatation was introduced and yielded valve areas between 1.5 and over 2.0 cm2. However, the double balloon technique is substantially more cumbersome, requires passage of two catheters through the atrial septum with an incidence of atrial septal defect, and results in significant hemodynamic sequelae during the procedure. This report describes a novel single balloon for PTMC. In contrast to the more conventionally used peripheral arterial balloons, this device was specifically designed for mitral stenosis. Results in 25 patients (mean age 60 +/- 5 years; range 29 to 87 years) showed an increase in value area from 0.9 +/- 0.2 cm2 to 1.6 +/- 0.5 cm2 (p less than 0.001). In contrast to the results reported with conventional balloon dilatation, there was no difference in the resultant valve area or in the incidence of complications among patients with more severely deformed valves compared with patients with more "ideal" valves for commissurotomy. An in vitro comparison of the pressure-volume characteristics of the conventional versus the Inoue balloon showed the latter to be more compliant, reaching nominal inflated diameter at 2.0 +/- 0.4 atm versus 3.3 +/- 0.5 atm for conventional balloons (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Determination of pulse wave velocities with computerized algorithms.

Careful determination of pulse wave velocity is important in the study of arterial viscoelastic properties, wave reflections, and ventricular-arterial interactions. In spite of its increasingly widespread use, there is as yet no standardized method for its determination. Most studies have manually identified the transit time of the pressure wave front as it travels over a known distance in the arterial system, but the issues of accuracy and reproducibility have not been addressed. This study was designed to investigate the efficacy of four computerized algorithms in the determination of pulse wave velocities in invasive as well as in noninvasive pressure determinations. The four methods were the identification of: (1) the point of minimum diastolic pressure, (2) the point at which the first derivative of pressure is maximum, (3) the point at which the second derivative of pressure is maximum, and (4) the point yielded by the intersection of a line tangent to the initial systolic upstroke of the pressure tracing and a horizontal line through the minimum point. High-fidelity aortic pressure recordings were obtained in 26 patients with a multi-sensor micromanometer catheter. Noninvasive brachial and radial pressure waveforms were recorded in 11 volunteers with external piezoelectric transducers. The results show that the first derivative method consistently provided results that were different from the other methods for both the invasive and noninvasive methods because of changes in the structure of the upstroke as the arterial pulse propagates distally. Although the minimum method worked well for the invasive determinations, it was erratic with the noninvasive determinations, probably because of the higher amount of noise and reflection in the latter. Among the four algorithms, the second derivative and the intersecting tangents methods worked well with both invasive and noninvasive determinations with mean variation coefficients of less than 7% and correlation coefficients between the methods of greater than 0.90 for all data. In conclusion, computerized algorithms allow accurate determination of pulse wave velocity in invasively and noninvasively measured arterial pressure waveforms.

Adult↗
PubMed1991

Arterial mechanical properties in dilated cardiomyopathy. Aging and the response to nitroprusside.

The effects of aging on arterial mechanical properties and the response to nitroprusside were examined in 25 patients with dilated cardiomyopathy. High-fidelity pressures were recorded with a multisensor catheter. Pulse wave velocity was determined between two sensors in the thoracic aorta. Arterial compliance was determined by an analysis of the diastolic waveform and cardiac output. At baseline, despite a similar systemic vascular resistance, the pulsatile load (e.g., arterial compliance) and wave transmission characteristics (e.g., pulse wave velocity) were altered with aging. Arterial compliance was reduced in older (greater than 50 yr, n = 8) versus younger (less than 35 yr, n = 8) patients (0.51 +/- 0.17 vs. 1.33 +/- 0.63 ml/mmHg, P less than 0.01) and intermediate in those 35-50 yr of age (n = 9, 0.72 +/- 0.40 ml/mmHg). There was a positive correlation between age and pulse wave velocity (r = +0.90). Nitroprusside infusion decreased resistance, increased arterial compliance, and lowered pulse wave velocity in all groups. Yet, advancing age was associated with a greater fall in wave velocity for a given fall in aortic pressure. The slope (K) of the relation between pulse wave velocity and aortic diastolic pressure progressively increased with age (0.01 +/- 0.03, 0.06 +/- 0.02, and 0.09 +/- 0.03 m/s-mmHg). Multiple linear regression analysis revealed a significant relation between K and age. These data demonstrate that in older patients with dilated cardiomyopathy the left ventricle is coupled to an arterial circulation that has a greater pulsatile load, despite a similar steady load. Furthermore, these age-related changes in the arterial system affect the hemodynamic response to pharmacologically-induced vasodilatation.

Adult↗
PubMed1991

Multidimensional scaling of painful and innocuous electrocutaneous stimuli: reliability and individual differences.

Multidimensional scaling was used to explore whether a single intensity dimension underlies the perception of both nonpainful and painful electrical stimuli, or whether separate dimensions are required. For the scaling (INDSCAL) procedure, 41 healthy volunteers judged the similarity between all pairs of 16 intensities, which ranged from imperceptible levels to pain tolerance. For the property mapping (PREFMAP) analysis, they rated each intensity on each of 16 property scales. INDSCAL revealed four dimensions that showed high levels of both test-retest and split-half reliability. The first dimension scaled stimuli from the lowest intensity to the pain threshold. This dimension was related to property scales of sensation, affect, and arousal, but not pain, suggesting a sensory magnitude dimension. The second dimension ordered the stimuli from mildly to severely painful and was related to the painful property scale, suggesting a pain intensity dimension. Third and fourth dimensions, which refined the scaling of nonpainful stimuli, were also found. Variability in the subjects' use of the painful and nonpainful dimensions was related to their choice of stimulus descriptors. Like clinical pain, laboratory pain requires multidimensional assessment.

Adolescent↗
PubMed1991

Percutaneous transvenous balloon mitral commissurotomy: When? For whom? An alternative to surgery in symptomatic mitral stenosis.

Percutaneous transvenous mitral commissurotomy (PTMC) is the therapy of choice for patients with mitral stenosis who are candidates for commissurotomy. PTMC also offers palliative therapy for patients who are not good surgical candidates. Patients with thin, pliable valve leaflets and little subvalvular disease are the best suited. Significant thrombus in the left atrium is a strong relative contraindication. PTMC with the Inoue balloon is technically easier to perform than is conventional balloon valvotomy and is better tolerated by most patients. During this procedure, the Inoue balloon is positioned against the mitral valve; it is repeatedly inflated at increasing balloon diameters until the transmitral valve gradient is sufficiently relieved. PTMC affords marked symptomatic improvement in most patients who undergo the procedure.

Catheterization↗
PubMed1991

Diastolic function in coronary artery disease.

Diastolic function in coronary artery disease is modified to a variable extent. There are distinct abnormalities produced during acute ischemia, and following myocardial infarction. The pathophysiology of diastolic abnormalities in these two syndromes is reviewed. During acute ischemia filling pressures of the left ventricle are increased. Pulmonary edema may be produced. Silent ischemia causes less of an increase in filling pressures. The diastolic pressure-volume relation is shifted in an upward manner with a variable contribution from altered myocardial relaxation, increased muscle stiffness, acute pericardial restriction, ventricular interaction, and acute chamber dilatation. The impairment of myocardial relaxation plays a central role and has been quantified in multiple clinical and experimental studies. Filling of the left ventricle during ischemia is altered due to the factors which shift the pressure-volume relation. The acute increase in left atrial pressure may increase filling rates somewhat surprisingly, given the reduced left ventricular compliance. Myocardial fibrosis following infarction may elevate filling pressures, but the degree of elevation is closely tied to the intravascular volume status. Shifts in the diastolic pressure-volume relation reflect a loss of chamber compliance due to an increase in muscle stiffness. Increased amounts of extracellular matrix, specifically collagen, produce this permanent increase in muscle stiffness which is central to the diastolic abnormalities in chronic coronary artery disease.

Angina Pectoris↗
PubMed1990

Cardiac catheterization in the patient with history of allergy to local anesthetics.

Patients with a history of allergic reactions to local anesthetic drugs present a difficult problem during evaluation for cardiac catheterization procedures. In the worst cases the procedure may be deferred, or even performed without local anesthesia. In the vast majority of patients an acceptable agent for safe local anesthetic use can be found. Skin testing beginning with very dilute solutions of preservative-free local anesthetic agent may be administered easily. This report describes the practical aspects of skin testing and local anesthetic agent selection in patients with a history of allergic reaction to local anesthetic drugs.

Adult↗
PubMed1990

Importation of methicillin-resistant Staphylococcus aureus from Baghdad to Dublin and subsequent nosocomial spread.

We report the spread of a methicillin- and gentamicin-resistant Staphylococcus aureus strain (MGRSA) from the Middle East and its subsequent dissemination within two hospitals in Dublin. The index case, a 30-year-old male with serious blast injuries was transferred from a Baghdad hospital to a Dublin hospital in May 1985. He was heavily infected with two MGRSA strains, one of which spread and was responsible for numerous episodes of nosocomial infection. This strain was very similar to MGRSA isolates recovered in a Baghdad hospital during 1984. This imported strain has now spread to two hospitals in our group causing sepsis. This report emphasizes the difficulty of detecting an imported strain in an endemic area, but above all points to the potential for spread when there is considerable movement of patients and personnel.

Adult↗
PubMed1990

Long-acting propranolol in the prophylaxis of migraine: a comparative study of two doses.

A randomized double-blind, cross-over study using treatment periods of 12 weeks with a 2-week washout, comparing two long-acting formulations of propranolol ('Inderal' LA 160 mg daily and Half-'Inderal' LA 80 mg daily) was performed after a placebo run-in of 4 weeks on 51 patients. The study indicated that both long-acting formulations were significantly better than placebo in reducing the frequency of migraine attacks (p less than 0.01). After 12 weeks there was a significantly lower (p = 0.03) frequency of migraine attacks in patients on the higher dose formulation than in those on the lower dose formulation. There was no significant difference in the frequency of side effects produced by the two formulations.

Adolescent↗
PubMed1990

Hemodynamic resistance as a measure of functional impairment in aortic valvular stenosis.

Calculated valve area depicts anatomical stenosis but does not quantify hemodynamic impairment. We propose that hemodynamic resistance, defined as the mean pressure gradient across the valve divided by mean flow rate during systolic ejection, gives a better indication of hemodynamic obstruction. This index was compared with Gorlin valve area in 40 patients with aortic stenosis. Calculated area ranged from 0.22 to 1.26 cm2, and mean transvalvular resistance ranged from 117 to 1,244 dyne.sec.cm-5. In general, resistance varied inversely with calculated area, but there was substantial variation about the mean relation. All of the variation could be accounted for by variations in the pressure gradients at each value of calculated area. Resistance was higher in proportion to area when flow and pressure gradient were high. Analysis of five published studies of a total of 83 valves showed that calculated area changed at least three times more than resistance when pressure gradient was varied. The utility of resistance as an index of stenosis is demonstrated by example calculations that show how during exercise a stenotic valve increases the ventricular work rate out of proportion to the work done on the peripheral resistance. These calculations are possible because hemodynamic resistance defines functional impairment in units commonly used for quantification of opposition to flow. Furthermore, resistance appears to be less dependent than area on conditions of measurement and does not require an empirical constant.

Aortic Valve↗
PubMed1989

Effects of ischemia, bypass surgery and past infarction on myocardial contraction, relaxation and compliance during exercise.

Abnormalities of left ventricular function during ischemia have been described in animal models and in humans. Exercise, while a physiologic means of inducing ischemia, has a complex effect on left ventricular function by itself. In addition, patients with coronary artery disease have a diversity of chronic changes in myocardial structure and function. Therefore, with use of micromanometer left ventricular pressure measurements and ventricular volumes, calculated from biplane cineangiograms, left ventricular function at rest and during exercise was studied in 57 patients. Exercise-induced ischemia produced a decrease in ejection fraction, an increase in end-systolic volume, dramatic increases in diastolic pressures and an upward shift in the diastolic pressure-volume relation. Central to these changes was abnormal myocardial contraction and relaxation, with reduced regional shortening and impaired left ventricular pressure decay. However, nonischemic areas were capable of augmented shortening, and global pressure decay did accelerate slightly. These findings demonstrate that exercise-induced adjustments in contraction and relaxation are intertwined with ischemia-related abnormalities. Exercise studies in patients after bypass surgery and in patients with scars from distant myocardial infarction were useful in clarifying confounding factors. For example, asynchrony of contraction and relaxation, and chronic changes in passive chamber properties, also compromise systolic and diastolic function during exercise. In patients with coronary artery disease without ischemia during exercise, left ventricular end-diastolic pressure, but not early diastolic pressure, increased during exercise. The increase in pressure was appropriate for a slight increase in end-diastolic volume in a ventricle with a steep pressure-volume relation. Furthermore, end-systolic volume, while maintained during exercise, was not reduced, as occurs normally.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗