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Biomedical subjects

B K Khandheria

Publications and source records attributed to B K Khandheria.

At least 19 recordsLinked to original sources
PubMed2004

Established and evolving indications for cardiac resynchronisation.

Randomised trials involving large number of patients have demonstrated the benefits of cardiac resynchronisation therapy (CRT) in patients with heart failure who have failed optimal medical treatment. Echocardiography plays an important role in defining dyssynchrony which is key to optimal patient selection. The electrocardiographic criteria for patient selection is supplemented by the finding of dyssynchrony on Doppler myocardial imaging, and echocardiography with Doppler myocardial imaging may eventually replace the electrocardiographic criteria for selection of patients who derive benefit from CRT.

Arrhythmias, Cardiac↗
PubMed2001

Thromboembolic complications after electrical cardioversion in patients with atrial flutter.

PURPOSE: To determine the incidence of thromboembolic complications after cardioversion in patients with atrial flutter. SUBJECTS AND METHODS: We reviewed 615 electrical cardioversions performed electively in 493 patients with atrial flutter. Embolic complications were evaluated during the 30 days after cardioversion. Follow-up data were obtained by follow-up visits and by contacting the treating physician. RESULTS: Anticoagulants had been administered in 415 cardioversions (67%). Cardioversion was successful in 570 procedures (93%). Three embolic events (in 3 patients) occurred in the 30 days after 550 successful cardioversions with completed follow-up (0.6% of successful procedures; 95% confidence interval, 0.1% to 1.6%). Two of the 3 patients had not been anticoagulated, whereas the third patient had subtherapeutic oral anticoagulation. No embolic event occurred in procedures performed with adequate anticoagulation. The incidence of embolism in patients regardless of subtherapeutic anticoagulation was 1% (3 of 303 successful cardioversions). CONCLUSIONS: We observed a low (0.6%) incidence of postcardioversion thromboembolic complications in patients with atrial flutter. Embolic events did not occur in patients with adequate anticoagulation.

Administration, Oral↗
PubMed2001

Sildenafil citrate, a selective phosphodiesterase type 5 inhibitor: urologic and cardiovascular implications.

Erectile dysfunction (ED) occurs in varying degrees in an estimated 20 to 30 million American men and is associated with adverse effects on quality of life; particularly personal well-being, family and social interrelationships. Research into ED has focused primarily on the physiologic mechanisms of corpus cavernosum smooth muscle relaxation, and penile erection as the end result of smooth muscle relaxation. These processes are mediated by cholinergic, nonadrenergic, noncholinergic (NANC, e.g., nitric oxide), vasoactive intestinal peptide (VIP), and potentially calcitonin gene-related peptide (CGRP) containing nerves. Release of nitric oxide following sexual stimulation from non-adrenergic, non cholinergic nerves and vascular endothelium activates guanylyl cyclase and induces intracellular cGMP synthesis. In turn, cGMP results in lowering intracellular concentrations, inhibits contractility of the penile smooth muscle, and induces an erectile response. Phosphodiesterase type 5 (PDE 5) is the predominant enzyme responsible for cGMP hydrolysis in trabecular smooth muscle. Activation of PDE 5 terminates NO-induced, cGMP-mediated smooth muscle relaxation, and subsequent penile flaccidity. Sildenafil citrate is a potent PDE type 5 reversible and selective inhibitor which blocks cGMP hydrolysis effectively. FDA approval of sildenafil citrate as the first oral agent for ED in males has resulted in significant interest. We discuss the clinical and pharmacologic properties of sildenafil citrate as well as the urologic and cardiac implications.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2001

Aortic valve sclerosis and aortic atherosclerosis: different manifestations of the same disease? Insights from a population-based study.

OBJECTIVES: The aim of this study was to examine the association between atherosclerosis risk factors, aortic atherosclerosis and aortic valve abnormalities in the general population. BACKGROUND: Clinical and experimental studies suggest that aortic valve sclerosis (AVS) is a manifestation of the atherosclerotic process. METHODS: Three hundred eighty-one subjects, a sample of the Olmsted County (Minnesota) population, were examined by transthoracic and transesophageal echocardiography. The presence of AVS (thickened valve leaflets), elevated transaortic flow velocities and aortic regurgitation (AR) was determined. The associations between atherosclerosis risk factors, aortic atherosclerosis (imaged by transesophageal echocardiography) and aortic valve abnormalities were examined. RESULTS: Age, male gender, body mass index (odds ratio [OR]: 1.07 per kg/m(2); 95% confidence interval [CI]: 1.02 to 1.12), antihypertensive treatment (OR: 1.93; CI: 1.12 to 3.32) and plasma homocysteine levels (OR: 1.89 per twofold increase; CI: 0.99 to 3.61) were independently associated with an increased risk of AVS. Age, body mass index and pulse pressure (OR: 1.21 per 10 mm Hg; CI: 1.00 to 1.46) were associated with elevated (upper quintile) transaortic velocities, whereas only age was independently associated with AR. Sinotubular junction sclerosis (p = 0.001) and atherosclerosis of the ascending aorta (p = 0.03) were independently associated with AVS and elevated transaortic velocities, respectively. CONCLUSIONS: Atherosclerosis risk factors and proximal aortic atherosclerosis are independently associated with aortic valve abnormalities in the general population. These observations suggest that AVS is an atherosclerosis-like process involving the aortic valve.

Age Factors↗
PubMed2001

Association of atrial fibrillation and aortic atherosclerosis: a population-based study.

OBJECTIVE: To examine the association between atrial fibrillation (AF) and aortic atherosclerosis in the general population. SUBJECTS AND METHODS: Transesophageal echocardiography was performed in 581 subjects, a random sample of the adult Olmsted County, Minnesota, population (45 years of age or older) participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. The frequency of aortic atherosclerosis was determined in 42 subjects with AF and compared with that in 539 subjects without AF (non-AF group). RESULTS: Subjects with AF were significantly older than non-AF subjects (mean +/- SD age, 82+/-10 vs 66+/-13 years, respectively; P<.001) and more commonly had hypertension (28 [66.7%] vs 288 [53.4%], respectively; P=.10). The 2 groups were similar in sex and frequency of diabetes mellitus, hyperlipidemia, or smoking history (P>.10). The odds of aortic atherosclerosis (of any degree) were 2.87 times greater (95% confidence interval [CI], 1.41-5.83; P=.004) and the odds of complex atherosclerosis (protruding atheroma >4 mm thick, mobile debris, or plaque ulceration) were 2.71 times greater (CI, 1.13-6.53; P=.03) in the AF group than in the non-AF group. Age was a significant predictor of aortic atherosclerosis (P<.001). After adjusting for age, the odds of atherosclerosis and complex atherosclerosis were not significantly different between the 2 groups (P=.13 and P=.75, respectively). CONCLUSIONS: In the general population, AF is associated with aortic atherosclerosis, including complex atherosclerosis. This association is related to age since both AF and aortic atherosclerosis are more frequent in the elderly population.

Adult↗
PubMed2001

Safety of electrical cardioversion in patients with previous embolic events.

OBJECTIVE: To assess thromboembolic complications in cardioversions in patients with atrial fibrillation or flutter and a previous embolic event. PATIENTS AND METHODS: The study population consisted of 104 patients with previous embolic events who underwent 128 electrical cardioversions for termination of atrial fibrillation or flutter. The primary outcome measure was successful cardioversion. RESULTS: Anticoagulants were administered in 118 procedures (92%). Cardioversion was successful in 108 (84%) of the 128 procedures. Only 1 embolic event occurred within 30 days after cardioversion (incidence, 0.9% of successful procedures; 95 % confidence interval, 0.02%-5.3%). The single embolic event was a transient neurologic deficit occurring 22 days after cardioversion in a patient with previous atrial fibrillation. This patient had a sub-therapeutic level of anticoagulation. Transesophageal echocardiography revealed no spontaneous echo contrast or thrombi before the procedure. No thromboembolism was noted in patients who had therapeutic anticoagulation or in those with failed cardioversion. CONCLUSION: Patients with previous embolism are not at additional risk of thromboembolic complications after cardioversion if anticoagulation is adequate.

Aged↗
PubMed2000

Effects of sildenafil citrate (Viagra) combined with nitrate on the heart.

BACKGROUND: Sildenafil citrate (Viagra) is indicated for the treatment of erectile dysfunction. Large and sudden decreases in systemic blood pressure were reported in a substantial number of patients taking sildenafil citrate combined with nitroglycerin. We studied the effect of sildenafil citrate on the relationship between changes in systemic blood pressure and coronary blood flow. METHODS AND RESULTS: Healthy male beagles were used to assess systemic blood pressure, pulmonary arterial pressure, and flow in the left circumflex artery (in which a critical stenosis was established) and left anterior descending coronary artery. After measurement of the hemodynamic variables, 2 mg/kg sildenafil citrate was administered via a nasogastric tube. Hemodynamic changes were monitored for 1 hour. Subsequently, the acute effect of nitrate combined with sildenafil citrate was studied by the bolus injection of 0.2 mg isosorbide dinitrate before and after sildenafil citrate. Systemic blood and pulmonary arterial pressures and circumflex flow did not change during this study; however, left anterior descending coronary arterial flow increased from 16.0+/-5.8 to 24.6+/-8.7 mL/min 1 hour after administration of sildenafil citrate. The prolongation of systemic blood pressure decrease and the circumflex flow decrement induced by isosorbide dinitrate after sildenafil citrate were significantly larger and longer than those before sildenafil citrate. CONCLUSIONS: Sildenafil citrate had the effect of vasodilation in a normal coronary artery; however, a combined effect with nitrate resulted in large and protracted decreases in systemic blood pressure and coronary blood flow in vessels with critical stenosis.

Administration, Oral↗
PubMed2000

Independent association of high blood pressure and aortic atherosclerosis: A population-based study.

BACKGROUND: Atherosclerosis of the thoracic aorta is associated with stroke. The association between hypertension, a major risk factor for stroke, and aortic atherosclerosis has not been determined in the general population. METHODS AND RESULTS: Transesophageal echocardiography was performed in 581 subjects, a random sample of the Olmsted County (Minnesota) population aged >/=45 years participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. Blood pressure was assessed by multiple office measurements and 24-hour ambulatory blood pressure monitoring. The association between blood pressure variables and aortic atherosclerosis was evaluated by multiple logistic regression, adjusting for other associated variables. Among subjects with atherosclerosis, blood pressure variables associated with complex aortic atherosclerosis (protruding plaques >/=4 mm thick, mobile debris, or ulceration) were determined. Age and smoking history were independently associated with aortic atherosclerosis of any degree (P:</=0.001) and with complex atherosclerosis (P:=0.002), whereas sex, diabetes mellitus, and body mass index were not. Multiple systolic and pulse pressure variables (office and ambulatory), but none of the diastolic blood pressure variables, were associated with atherosclerosis and complex atherosclerosis, adjusting for age and smoking. Among subjects with atherosclerosis, the odds of complex atherosclerosis increased as ambulatory out-of-bed systolic blood pressure increased (odds ratio 1.43 per 10 mm Hg increase, 95% CI 1. 10 to 1.87) and with hypertension treatment, adjusting for age and smoking history. CONCLUSIONS: High blood pressure is independently associated with aortic atherosclerosis. Among subjects with atherosclerosis, high blood pressure is associated with complex atherosclerosis.

Age Distribution↗
PubMed2000

Left atrial appendage flow velocities in subjects with normal left ventricular function.

The objectives of this study were to establish reference values and define the determinants of left atrial appendage (LAA) flow velocities in the general population. LAA flow velocities (contraction and filling velocities) were assessed by transesophageal echocardiography in 310 subjects aged > or = 45 years, sampled from the population-based Stroke Prevention: Assessment of Risk in a Community study. All subjects were in sinus rhythm, with preserved left ventricular systolic function (ejection fraction > or = 50%), and without valvular disease. Values of LAA contraction and filling velocities were established for various age groups in the population. Age was negatively associated with LAA contraction and filling velocities, which decreased by 4.1 cm/s (p < 0.001) and 2.0 cm/s (p < 0.01) for every 10 years of age, respectively. Contraction velocities were 5 cm/s higher in men than in women (p < 0.05). After adjusting for age and sex, heart rate was independently associated with LAA contraction velocities (p < 0.001; nonlinear association). Body surface area, left atrial size, left ventricular mass index, and a history of previous cardiac disease or hypertension showed no significant association with LAA flow velocities (p > 0.05). Furthermore, detailed analysis of 24-hour ambulatory blood pressure data (available in 253 subjects) showed no association between various blood pressure parameters (systolic and diastolic blood pressure, out-of-bed and in-bed measurements) and LAA flow velocities (all p > 0.05). In summary, the present study establishes the reference values for LAA flow velocities in a large sample of the general population. LAA flow velocities progressively decline with age in subjects with preserved left ventricular systolic function.

Age Factors↗
PubMed2000

Evaluation of coronary flow reserve in hypertensive patients by dipyridamole transesophageal doppler echocardiography.

This study evaluates the coronary flow reserve (CFR) in hypertensive patients with and without left ventricular (LV) hypertrophy. CFR was assessed by transesophageal Doppler echocardiography in 15 normal subjects (group I), 21 hypertensive patients without LV hypertrophy (group II), and 27 hypertensive patients with LV hypertrophy (group III). All hypertensive patients were complaining of typical anginal pain and had normal coronary angiograms. The sample volume was placed at the bifurcation of the left main and left anterior descending coronary arteries. Coronary blood flow velocities were evaluated at rest, 2 minutes after dipyridamole infusion, and 2 minutes after intravenous aminophylline. The ratios of dipyridamole to rest peak diastolic and systolic velocities were considered as indexes of CFR. Peak diastolic velocity ratio was significantly lower in group III than in groups I and II (1.6 +/- 0.2, 2.7 +/- 0.4, and 2.1 +/- 0.2, respectively; p <0.05), and it was significantly lower in group II than I (p <0.05). The peak systolic velocity ratio was significantly lower in group III than in groups I and II (1.7 +/- 0.3, 2.8 +/- 0.3, and 2.1 +/- 0.2, respectively; p <0.05), and it was significantly lower in group II than I (p <0.05). The peak diastolic velocity ratio was inversely related to systolic blood pressure, diastolic blood pressure, and LV mass index (r = -0.48, -0. 51, and -0.37 respectively) in hypertensive patients. It is concluded that CFR is significantly impaired in hypertensive patients, especially those with LV hypertrophy, compared with healthy subjects. The degree of impairment of CFR is related to LV mass index.

Angina Pectoris↗
PubMed2000

Predictors of cerebrovascular events and death among patients with valvular heart disease: A population-based study.

BACKGROUND AND PURPOSE: There is little population-based information on cerebrovascular events and survival among valvular heart disease patients. We used the Kaplan-Meier product-limit method and the Cox proportional hazards model to determine rates and predictors of cerebrovascular events and death among valve disease patients. METHODS: This population-based historical cohort study in Olmsted County, Minnesota, reviewed residents with a first echocardiographic diagnosis of mitral stenosis (n=19), mitral regurgitation (n=528), aortic stenosis (n=140), and aortic regurgitation (n=106) between 1985 and 1992. RESULTS: During 2694 person-years of follow-up, 98 patients developed cerebrovascular events and 356 died. Compared with expected numbers, these observations are significantly elevated, with standardized morbidity ratio of 3.2 (95% CI, 2.6 to 3.8) and 2. 5 (95% CI, 2.2 to 2.7), respectively. Independent predictors of cerebrovascular events were age, atrial fibrillation, and severe aortic stenosis. The risk ratio of severe aortic stenosis was 3.5 (95% CI, 1.4 to 8.6), with atrial fibrillation conferring greater risk at younger age. Predictors of death were age, sex, cerebrovascular events, ischemic heart disease, and congestive heart failure, the greatest risk being among those with both congestive heart failure and cerebrovascular events (risk ratio=8.8; 95% CI, 5. 8 to 13.4). Valve disease type and severity were not independent determinants of death. CONCLUSIONS: The risk of cerebrovascular events and death among patients with valve disease remains high. Age, atrial fibrillation, and severe aortic stenosis are independent predictors of cerebrovascular events, and age, sex, cerebrovascular events, congestive heart failure, and ischemic heart disease are independent predictors of death in these patients.

Adolescent↗
PubMed2000

Asymptomatic occlusion of the left main coronary artery by an aortic pseudoaneurysm.

Extrinsic compression of the left main coronary artery is a rare cause of coronary ischemia. We describe a 35-year-old Asian woman with complete asymptomatic occlusion of the left main coronary artery by a large aortic pseudoaneurysm. She underwent repair of the pseudoaneurysm and coronary artery bypass grafting at the Mayo Clinic in Rochester, Minn. The differential diagnosis is discussed. Based on this patient's age and associated vascular lesions, we conclude that Takayasu arteritis was the most likely cause of her condition.

Adult↗
PubMed1999

Frequency of atrial septal aneurysms in patients with cerebral ischemic events.

BACKGROUND: Atrial septal aneurysm (ASA) is a putative risk factor for cardioembolism. However, the frequency of ASA in the general population has not been adequately determined. Therefore, the frequency in patients with cerebral ischemic events, compared with the frequency in the general population, is poorly defined. We sought to determine the frequency of ASA in the general population and to compare the frequency of ASA in patients with cerebral ischemic events with the frequency in the general population. METHODS AND RESULTS: The frequency of ASA in the population was determined in 363 subjects, a sample of the participants in the Stroke Prevention: Assessment of Risk in a Community study (control subjects), and was compared with the frequency in 355 age- and sex-matched patients undergoing transesophageal echocardiography in search of a cardiac source of embolism after a focal cerebral ischemic event. The proportion with ASA was 7.9% in patients versus 2.2% in control subjects (P=0.002; odds ratio of ASA, 3.65; 95% CI, 1.64 to 8.13, in patients versus control subjects). Patent foramen ovale (PFO) was detected with contrast injections in 56% of subjects with ASA. The presence of ASA predicted the presence of PFO (odds ratio of PFO, 4.57; 95% CI, 2.18 to 9.57, in subjects with versus those without ASA). In 86% of subjects with ASA and cerebral ischemia, transesophageal echocardiography did not detect an alternative source of cardioembolism other than an associated PFO. CONCLUSIONS: The prevalence of ASA based on this population-based study is 2.2%. The frequency of ASA is relatively higher in patients evaluated with transesophageal echocardiography after a cerebral ischemic event. ASA is frequently associated with PFO, suggesting paradoxical embolism as a mechanism of cardioembolism. In patients with cerebral ischemia and ASA, ASA (with or without PFO) commonly is the only potential cardioembolic source detected with transesophageal echocardiography.

Aged↗
PubMed1999

Remote telemedical interpretation of neonatal echocardiograms: impact on clinical management in a primary care setting.

OBJECTIVE: The purpose of this study was to evaluate the utility of telemedical echocardiographically assisted neonatal cardiovascular evaluation in a primary care setting. BACKGROUND: Neonates with congenital heart disease are frequently born far from pediatric subspecialty centers and can be clinically unstable at presentation. Recent advances in telecommunication technology have made it possible to transmit echocardiographic images over long distances. This technology may be beneficial to newborns with heart defects who are born in primary care centers. METHODS: A retrospective review of all telemedical echocardiograms obtained from neonates (aged 1 day to 30 days) was performed. A telemedical link was created using a T-1 transmission line and a standard voice telephone line between the Mayo Clinic, Rochester, Minnesota (pediatric cardiology site), and the Altru Clinic, Grand Forks, North Dakota (primary care site), which is a general pediatric practice 400 miles from Rochester. Neonates with possible cardiac disorders were identified by the general pediatricians, who then requested telemedical echocardiography. RESULTS: The 133 neonates had 161 T-1 echocardiograms. Median patient age was two days (range, one day to 29 days). One hundred thirty-two of 133 initial echocardiograms (99%) were obtained because of urgent indications. Transmitted images provided adequate diagnostic information in all patients. Seventy-nine neonates (59%) had a change in medical management or required cardiology follow-up. An immediate change in management occurred in 32 patients (24%), including seven in whom emergency transfer was either arranged or avoided. CONCLUSIONS: Telemedical echocardiography provides accurate diagnostic data in neonates. Rapid telediagnosis facilitates appropriate care of sick neonates with possible congenital heart disease in the primary care setting. Unnecessary long-distance transfers can be avoided with this technology.

Heart Defects, Congenital↗