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Biomedical subjects

L Michael Prisant

Publications and source records attributed to L Michael Prisant.

At least 19 recordsLinked to original sources

Phosphodiesterase-5 inhibitors and their hemodynamic effects.

Erectile dysfunction occurs commonly in untreated and treated hypertensive patients, impairing adherence to treatment and quality of life. Furthermore, it is a marker for enhanced risk for cardiovascular disease. Phosphodiesterase type 5 (PDE5) inhibitors, sildenafil, vardenafil, and tadalafil, provide effective treatment of erectile dysfunction. They reduce blood pressure in healthy patients: sildenafil 100 mg, -3.7/-3.6 mm Hg; vardenafil 20 mg, -7.5/-8 mm Hg; and tadalafil 20 mg, -1.6/-0.8 mm Hg. Greater declines in blood pressure with a PDE5 inhibitor may be observed in treated and untreated hypertensive patients. The additive effect of PDE5 inhibitors with one or multiple antihypertensive drugs is modest. alpha(1)-Blockers, except tamsulosin, may result in larger declines in blood pressure and cause orthostatic hypotension. Thus, caution should be exercised by using the lowest doses of proportional, variant(1)-blockers and PDE5 inhibitors in combination. Nitrates in combination with PDE5 inhibitors cause a profound decline in blood pressure and are contraindicated.

3',5'-Cyclic-GMP Phosphodiesterases↗

Relationship between glycosylated hemoglobin and arterial elasticity.

Arterial elasticity is decreased in diabetes, but it is unclear whether there is a relationship between glycosylated hemoglobin (HbA1c) and arterial elasticity. To evaluate this question, 111 subjects with diabetes mellitus had HbA1c and arterial elasticity determined in an academic outpatient setting. Three measurements of arterial elasticity indices were obtained supine using the HDI/PulseWave CR-2000 Research CardioVascular Profiling System (Hypertension Diagnostics Inc., Eagan, MN). The study population was 49% black and 51% women. Population characteristics included age, 49.2 years; duration of diabetes, 12.1 years; HbA1c, 8.9%; large artery elasticity, 11.8 mL/mm Hg x 10; and small artery elasticity, 4.7 mL/mm Hg x 100. Age correlated with diminished large artery elasticity. Women had a lower large artery elasticity than men (10.6 vs. 13.3 mL/mm Hg x 10; p = 0.0002). Decreasing small artery elasticity was associated with increasing age (p = 0.0001), HbA1c (p = 0.0184), and African-American ethnicity (p = 0.0306). Women had less small artery elasticity than men (3.8 vs. 5.8 mL/mm Hg x 100; p = 0.0001). Black diabetic patients had a reduced arterial elasticity compared with whites. Increasing HbA1c is associated with decreasing small artery elasticity, but not large artery elasticity. In diabetic patients, small artery elasticity is reduced to a greater extent in women than men and in blacks than whites.

Age Factors↗

Ophthalmoscopic findings in malignant hypertension.

Malignant hypertension may present with retinopathy, choroidopathy, and optic neuropathy. Flame-shaped retinal hemorrhages, an early finding, are due to smooth muscle necrosis and bleeding along the nerve fiber layer. Cotton-wool spots, or cytoid bodies, are not exudates, but rather are retinal infarcts. Hypertensive optic neuropathy is a late finding. Optical coherence tomography is a relatively new imaging technique for evaluating retinal thickness and the location of pathology in patients with malignant hypertension.

Adult↗

Antihypertensive pharmacobezoar.

Most antihypertensive drugs have known side effects that are elicited by the careful clinician taking care of hypertensive patients. However, many antihypertensive medications utilize drug delivery systems that prolong the duration of blood pressure reduction. The gastrointestinal therapeutic system that is used with nifedipine, isradipine, and verapamil has a unique side effect. Obstruction may occur at the site of a previous surgical repair (pyloric stenosis or gastroplasty) or stenosis of the esophagus, small intestine, or colon. The same delivery system is used with methylphenidate, oxybutynin, glipizide, and doxazosin. Although this complication is rare, physicians who prescribe and care for hypertensive patients should recognize this potential problem.

Antihypertensive Agents↗

Hyperthyroidism: a secondary cause of isolated systolic hypertension.

Isolated systolic hypertension is the most common form of hypertension, especially among patients 50 years or older. What is not appreciated is that there are secondary causes of isolated systolic hypertension. Hyperthyroidism increases systolic blood pressure by decreasing systemic vascular resistance, increasing heart rate, and raising cardiac output. Potential cardiovascular consequences of hyperthyroidism include atrial arrhythmias (especially atrial fibrillation), pulmonary hypertension, left ventricular hypertrophy, and heart failure. The prevalence of hypertension is greater among hyperthyroid patients than euthyroid patients. Whether there is a blunted nocturnal decline in ambulatory blood pressure among hyperthyroid patients is more controversial. Treatment is associated with a reduction in systolic blood pressure, heart rate, and cardiac output.

Blood Pressure↗

Elevated endothelin-1 levels are associated with decreased arterial elasticity in hypertensive patients.

Endothelin-1 stimulates collagen synthesis and is increased in hypertension, but its effect on collagen degradation remains unknown. The current study tested the hypothesis that elevated endothelin-1 levels are associated with decreased collagenase activity, markers of collagen degradation, and arterial compliance in hypertensive patients. Normotensive (n = 10) and hypertensive (n = 13) patients who were not on any antihypertensive medication were recruited, and small and large artery elasticity index, systemic vascular resistance, pulse pressure, and blood pressure were determined using blood pressure waveform analysis. Large artery elasticity index and collagen degradation products were decreased whereas endothelin-1, systemic vascular resistance, and pulse pressure were elevated in hypertensive patients. Plasma endothelin-1 was negatively correlated with a cross-linked C-terminal telopeptide of collagen type I, a collagen degradation marker (r = -0.43; p = 0.04), collagenase matrix metalloproteinase-1 (r = -0.48; p = 0.02), and large artery elasticity (r = -0.45; p = 0.03) and positively correlated with pulse pressure (r = 0.68; p = 0.0005). These results suggest that endothelin-1 contributes to decreased arterial compliance in hypertension via inhibition of collagen degradation.

Adult↗

Arterial elasticity and erectile dysfunction in hypertensive men.

Erectile dysfunction is a common symptom among hypertensive patients that impairs quality of life and adherence to antihypertensive pharmacologic therapy. It is also associated with cardiovascular risk factors and disease. The Sexual Health Inventory in Men (SHIM) was administered to 105 ambulatory hypertensive patients, and large and small artery elasticity indices were measured. Each variable was examined in a simple linear regression model or 1-way analysis of variance model to determine each variable's relationship with the SHIM score. Variables that were significantly associated with the SHIM score in the univariate models included age, duration of hypertension, peripheral vascular disease, and small artery elasticity. Large artery elasticity was not significantly associated with the SHIM score. In the multivariate model, age, hypertension duration, and peripheral vascular disease were associated with a lower SHIM score. This study demonstrates a relationship between erectile dysfunction and reduced artery elasticity.

Blood Pressure↗

Fibromuscular dysplasia: an uncommon cause of secondary hypertension.

Fibromuscular dysplasia is a noninflammatory vascular disease that commonly affects the distal two thirds of the renal artery and branch vessels, but occasionally involves other arteries. Progression of stenosis occurs in 16%-38% of renal arteries. Although the etiology is unknown, genetic studies suggest a relationship to the angiotensin-converting enzyme I allele. Thin, young Caucasian women without a family history of hypertension are most commonly affected. An abdominal or flank systolic-diastolic bruit is an important clue for the diagnosis. Most noninvasive screening tests are not sensitive or reproducible to be used to rule out renal artery stenosis, but digital subtraction renal angiography usually confirms the diagnosis. Percutaneous renal artery angioplasty is the treatment of choice, but may not result in normalization of blood pressure if diagnosis is delayed. Since restenosis occurs, continued follow-up is necessary.

Fibromuscular Dysplasia↗

Obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome is caused by upper airway collapse during inspiration, causing intermittent hypoxemia, hypercapnia, acidosis, sympathetic nervous system activation, and arousal from sleep. Nighttime blood pressure is higher, but unexpectedly, daytime hypertension occurs. The prevalence of hypertension is very high and the incidence of hypertension increases as the number of apneic and hypopneic events per hour rises. Obesity is a major predisposing factor for the development of obstructive sleep apnea. Daytime sleepiness, snoring, and breathing pauses are important symptoms to elicit from the patient or sleep partner. Resistant hypertension is an important clue. Overnight polysomnography is required for diagnosis. Weight loss, avoidance of nocturnal sedatives, cessation of evening alcohol ingestion, and avoidance of the supine position during sleep are initial therapeutic actions in mild obstructive sleep apnea syndrome. Continuous positive airway pressure is the treatment of choice for patients unable to find relief from lifestyle changes. Blood pressure modestly improves with treatment.

Angiotensin-Converting Enzyme Inhibitors↗

Assessment of test repeatability of arterial stiffness index.

BACKGROUND: Increased arterial stiffness is an early indicator of vascular disease. Several methods may be used to determine arterial stiffness. One method obtains an arterial stiffness index from the vascular dynamics of oscillometric-derived brachial artery pressure. METHODS: To determine the test-retest repeatability of the CardioVision MS-2000, 47 healthy hospital employees had five consecutive measurements of arterial stiffness index measured after a 5-10 min period of rest and then repeated after an average of 146.8 days. Their mean age was 37 years and 71% were women. RESULTS: The mean arterial stiffness index was 39.6+/-9.7 and 37.2+/-10.5 mmHg x10 (P=0.22) for the first and second time period, respectively. We computed an intraclass correlation coefficient of 0.31 and 0.33 for the first and second time periods, which is the measure of consistency or agreement of arterial stiffness index values within cases. The intraclass correlation coefficient for systolic blood pressure, diastolic blood pressure, heart rate and arterial stiffness index were 0.68 (P=0.0001), 0.70 (P=0.0001), 0.35 (P=0.02) and 0.25 (P=0.08), respectively. CONCLUSION: The results of this study suggest poor test-retest repeatability if consecutive measurements are used. The intraclass correlation coefficient, however, could be improved by eliminating the highest and lowest value from a set of measurements.

Adult↗

Nonarteritic anterior ischemic optic neuropathy.

Nonarteritic anterior ischemic optic neuropathy is a common cause of sudden, painless loss of vision present commonly on awakening from sleep. It most commonly affects middle-aged and elderly Caucasian men and women. Involvement of the opposite eye occurs within 3 years in less than 43% of patients. Hypertension, diabetes, and nocturnal hypotension are risk factors. A congenital small cup-to-disk ratio also predisposes to the optic nerve ischemia. There is no effective therapy to treat patients acutely or to prevent recurrence. After 6 months of careful follow-up, 57.3% of patients will have no significant change or worsening of their vision in the involved eye.

Arteritis↗

Gynecomastia and hypertension.

Palpable dense and mobile subareolar tissue in the male breast defines the presence of gynecomastia. For the hypertension specialist, breast enlargement in men provides a clue to a secondary cause of hypertension or an adverse antihypertensive drug reaction. Hyperthyroidism, chronic renal failure, adrenal hyperplasia or tumors, amphetamine, cyclosporine, and anabolic steroids are secondary causes of hypertension associated with gynecomastia. Reserpine, methyldopa, and spironolactone are older drugs associated with gynecomastia; however, calcium antagonists (more commonly), angiotensin-converting enzyme inhibitors, and alpha1 blockers may also be associated with this finding. Treatment is directed to removal of the underlying cause.

Antihypertensive Agents↗

Aortic dissection.

Aortic root enlargement is generally asymptomatic, with few clinical clues, but may be observed as an incidental finding on a chest x-ray, echocardiogram, or contrast-enhanced computerized tomogram of the chest. Aortic dissection is one of the most feared complications of hypertension. A history of hypertension is commonly present, but the systolic blood pressure in type A dissection (proximal to the left subclavian artery) has been found to be less than 150 mm Hg in 64% of patients. However, 71% of type B dissections (distal to the left subclavian artery) present with a systolic blood pressure 150 mm Hg or higher (International Registry of Acute Aortic Dissection). Most frequently, onset of symptoms is in the daytime, especially between 6 a.m. and noon. Severe sharp chest pain that is abrupt in onset is the most likely presentation. Migrating pain is uncommon. Although a pulse deficit with decreased or absent carotid, brachial, or femoral pulses occurs in only 30% of patients, three or more deficits predict an in-house mortality of about 60%. A chest x-ray finding of a widened mediastinum is present in 62.6% of type A and 56% of type B dissections. Contrast-enhanced computerized tomography or transesophageal echocardiography is the most commonly performed procedure for diagnosis. In-house mortality has been found to be 32.5% in type A dissections and 13% in type B dissections.

Acute Disease↗

Polycystic kidney disease.

Polycystic kidney disease, an inherited systemic disorder, is characterized by the development of multiple cysts in the kidneys and other organs. Patients can present at any age, but more often come to clinical attention (unless there is a family history) after age 30. Patients who are diagnosed before age 30 have a worse renal survival. Although palpation of the abdomen occasionally provides a clue to the presence of polycystic kidney disease, radiographic procedures most often suggest the diagnosis. Mutations in the PKD1 or PKD2 genes give rise to cyst formation. Flank pain, hematuria, polyuria, nephrolithiasis, urinary tract infections, and hypertension may be part of the syndrome of polycystic kidney disease. It is the fourth most common cause of end-stage renal disease. Blood pressure treatment goals are less than 130/80 mm Hg. Treatment should include the use of angiotensin-converting enzyme inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗

Chronotherapeutic oral drug absorption system verapamil is effective in reducing morning blood pressure in African Americans: a post hoc analysis of the chrono trial.

Results of several clinical trials have shown that verapamil is effective in reducing blood pressure (BP) in African Americans, a population at high risk for hypertension and target-organ damage. Nonetheless, adequate control of BP is perceived as difficult to achieve in this population. A post hoc analysis of data from the community-based CHRONO trial (Controlling Hypertension in the moRning with a ChrONO medication) was undertaken to assess racial/ethnic differences in the safety and efficacy of the Chronotherapeutic Oral Drug Absorption System (CODAS) formulation of verapamil in a real-world setting. Once-daily administration of the CODAS formulation of verapamil significantly reduced morning BP (P<0.0001) regardless of race or ethnicity. In the African-American population (N=466), the response rate for systolic BP (<140 mmHg or > or =10% reduction from baseline) and diastolic BP (<90 mmHg or reduction > or =10 mmHg from baseline) combined was 70.8%, and 60% of those individuals responded at the lowest (200 mg) dose. Of the 59.7% of African Americans who reached the target BP of <140/90 mmHg, 64% did so at the 200-mg dose. Response rates were not affected by gender, age or treatment history, and CODAS-verapamil was well tolerated in all ethnic/racial treatment groups. In a trial conducted in actual clinical practices, the CODAS formulation of verapamil was shown to be safe and effective in African Americans, Caucasians, Hispanics and Asians.

Administration, Oral↗

Hypertensive heart disease.

Hypertensive heart disease encompasses anatomical changes and altered physiology of heart muscle, coronary arteries, and great vessels. Left ventricular hypertrophy is not only a target organ response to increased afterload, but is also the most potent cardiovascular risk factor. Regression of hypertrophy reduces morbidity and mortality. Heart failure may be present in the absence of a reduction of myocardial contractility. Ischemic heart disease occurs in the absence of epicardial coronary disease. Left atrial size and atrial fibrillation are associated. Potentially lethal ventricular arrhythmias and sudden cardiac death are more common in hypertensive patients. The relationship of aortic root size to blood pressure is weaker than expected; however, the relationship to aortic dissection is stronger. Careful attention and treatment of left ventricular hypertrophy, heart failure, ischemic heart disease, and atrial fibrillation will improve survival.

Blood Pressure↗

Abdominal aortic aneurysm.

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the artery that is 1.5 times the diameter of the normal segment. The most common location for an aortic aneurysm is the infrarenal segment where a diameter that exceeds 3 cm in diameter is considered aneurysmal. Duplex ultrasonography and spiral computerized tomography are the imaging modalities most commonly performed to detect the longitudinal and transverse diameter of the aorta. The prevalence of AAA may be increasing. Smoking, male gender, and increasing age are the most powerful predictors of AAA. Considering the higher prevalence of hypertension, it is surprising that the prevalence of AAA among African-American men is 39% less than white men. The risk of rupture is independently associated with female gender, large initial aneurysm diameter, lower forced expiratory volume in the first second, current smoking, and higher mean blood pressure. Inflammation rather than atherosclerosis may be essential to the development of AAA. Treatment is directed at smoking cessation and control of blood pressure and lipids. Beta blockers (propranolol) have not been shown to modify aneurysm growth rates, but drop out rates in the studies have been high. Antibiotics do show a modest benefit. Surgery is generally performed when the aneurysm exceeds 5.5 cm in men. For women, an AAA size between 4.5 cm and 5.0 cm is recommended for elective repair.

Age Distribution↗