Renal revascularization in the azotemic hypertensive patient resistant to therapy

We undertook this study to assess the frequency of renovascular hypertension in patients with azotemia and hypertension refractory to drug therapy and to determine the effects of renal revascularization on blood pressure and renal function in these subjects. Thirty-nine of 106 consecutive patients admitted for diagnostic evaluation of severe hypertension proved to have renovascular hypertension. Of 21 hypertensive patients with renal insufficiency, 10 appeared to have renovascular hypertension with either bilateral atherosclerotic renovascular disease or unilateral renal arterial stenosis in a solitary functioning kidney. Medical therapy in the hospital often induced further deterioration of renal function despite enhanced blood-pressure control. However, surgical revascularization or percutaneous transluminal angioplasty produced improvement or stabilization of renal function and control of blood pressure in all patients with azotemia who were treated in this manner, despite longstanding hypertension. The benefits of therapy have persisted for 10 to 42 months of follow-up. These studies indicate that refractory hypertension in association with renal insufficiency is a relatively common clinical presentation for renovascular hypertension and bilateral renal-artery disease. Diagnostic evaluation and consideration of renal revascularization appear warranted in such patients, both for the control of the hypertension and for improvement in renal function.     

Uncemented total hip replacements and thigh pain

We reviewed 51 uncemented total hip replacements (THRs) in 44 patients (mean age 62 years) and average postoperative follow-up period of 4 years. The evaluation system used was based on that of D'Aubigne-Postel-Charnley, and the excellent and very good results totalled over 90%. There were no revisions or aseptic loosenings, and only one late infection and one death due to cardiac infarction. Special attention was paid to the socalled thigh pain phenomenon which, despite current views, was found to be unexpectedly low (only one case) and also gone within 2 years. We feel that the design of the prosthesis used, its kind of alloy, the anatomic shape of the stem and the low modulus of the elasticity as well as the avoidance of the press fitting technique at the distal part of the stem are important factors in avoiding the stress shielding phenomenon and thigh pain.     

Regional myocardial motion and thickening assessed at rest by ECG-gated99mTc-MIBI emission tomography and by magnetic resonance imaging

We have validated ECG-gated emission tomography using technetium-99m methoxyisobutylisonitrile for the assessment of regional ventricular function by comparing it with cine magnetic resonance imaging (MRI). Gated tomography was performed at rest in 24 patients referred for myocardial perfusion imaging [17 males and seven females with a mean age of 58 years, nine of whom had had a previous myocardial infarction (MI)]. Scores were assigned to each of nine myocardial segments for wall motion and for thickening. Cine MRI was analysed in an identical fashion. Four out of 216 (2%) segments were uninterpretable by gated tomography because of inadequate tracer uptake. In eight patients without coronary artery disease (CAD), wall motion and thickening were normal by both methods. Gated tomography showed abnormal wall motion or thickening in all patients with previous MI and in five of seven patients with CAD but no prior MI. Association between wall motion and thickening was good (r _s=0.86). Overall, there was good agreement between gated tomography and MRI for both wall motion (178/212 segments, =0.66) and wall thickening (184/212 segments, =0.69). In segments with severely reduced perfusion, however, there was poorer agreement (=0.31). Interobserver and intraobserver agreement was high ( from 0.61 to 0.78). Thus, in patients investigated for CAD, there is good overall agreement between gated tomography and MRI but the agreement is lower in segments with severe perfusion defects.     

Converting enzyme inhibition in hypertensive emergencies.

The diagnostic and therapeutic value of the angiotensin converting enzyme inhibitor teprotide (SQ 20881) was assessed in 18 patients with hypertensive emergencies. Mean blood pressure fell 31 +/- 18 mm Hg in the 10 subjects who responded to 1 mg/kg body weight administered intravenously, whereas it fell 5 +/- 3 mm Hg in the eight nonresponders. In patients who had received no previous drug treatment, log baseline plasma renin activity and change in mean blood pressure after SQ 20881 correlated significantly (r = 0.651, P less than 0.05). After acute therapy with SQ 20881, the patients who had a satisfactory response to the drug were treated with propranolol and a relatively normal sodium intake (88 meq/day). Nonresponders were treated with diuretics and sodium restriction (10 meq/day), and intermediate responders were given combination therapy. Mean blood pressure responded favorably within 24 h to the chosen regimen for each group from 152 +/- 47 to 102 +/- 31 mm Hg. SQ 20881 allows prompt evaluation of the role of renin in hypertensive emergencies and permits early choice of appropriate therapy based on the prevailing mechanism.     

Effect of arginine vasopressin on coronary and systemic hemodynamics in man

Arginine vasopressin is a potent constrictor of isolated arterial segments in vitro. However, it is disputed whether, in vivo, arginine vasopressin acts as either a systemic or coronary vasoconstrictor. The purpose of this study was to determine the effect of arginine vasopressin on coronary and systemic vascular tone in man. Six patients undergoing routine diagnostic cardiac catheterization were studied. At angiography, all patients were found to have severe coronary artery disease. Cardiac and systemic pressures and coronary blood flow as well as serum arginine vasopressin and osmolality levels were measured before and after administration of hypertonic contrast dye and then following intravenous injection of an analog inhibitor of arginine vasopressin. At baseline, serum arginine vasopressin levels were within the normal range in all patients, but, following infusion of contrast dye, rose above physiological levels in 5 patients. In these latter patients, there were no significant changes in coronary and systemic hemodynamics between baseline (condition 1), following administration of contrast dye (condition 2) and 10 minutes after injection of arginine vasopressin inhibitor (condition 3). Mean coronary sinus blood flow (ml/min) and mean coronary vascular resistance (dyne.sec.cm-5) were 184 +/- 49 and 41,235 +/- 8275 during condition 1, 204 +/- 62 and 39,442 +/- 8781 during condition 2, and 192 +/- 75 and 44,930 +/- 11455 during condition 3. Mean arterial pressure (mm Hg) and mean systemic vascular resistance (dyne.sec.cm-5) during conditions 1, 2 and 3 were 105 +/- 12 and 1454 +/- 174, 114 +/- 21 and 1432 +/- 210, and 114 +/- 15 and 1436 +/- 147, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vasodepressor role of endogenous bradykinin assessed by a bradykinin antagonist

This study was designed to examine the contribution of bradykinin to the depressor effect of different antihypertensive drugs in two-kidney renovascular hypertensive rats, using a new specific antagonist of bradykinin. First, the inhibitory capacity of this peptide for exogenously injected bradykinin (75-200 ng) was tested. An inhibition of the vasodepressor action of bradykinin by over 50% was found when the bradykinin inhibitor was infused at a rate of 40 micrograms/min, with little difference at higher rates of infusion. This inhibitor then was infused in three groups of renovascular hypertensive rats after their blood pressure had been decreased by pretreatment with the converting enzyme inhibitor enalapril (MK 421), saralasin, or sodium nitroprusside, respectively. Infusion of the inhibitor produced an immediate 30% increase in blood pressure only in the enalapril-treated group. These results indicate that bradykinin is involved in the decrease of blood pressure produced by converting enzyme inhibition in experimental renovascular hypertension.     

Endothelin-aldosterone interaction and proteinuria in low-renin hypertension

OBJECTIVE: To investigate whether endothelin and aldosterone participate in the increased prevalence and severity of nephrosclerosis in human low-renin hypertension, analogous to observations in experimental hypertension. DESIGN: Comparison of endothelin, aldosterone and their relationships with proteinuria, in hypertensive patients with high aldosterone : renin ratios (HARR group, n = 14) or normal aldosterone : renin ratios (NARR group, n = 15). METHODS: Urine protein and radioimmunoassay measurements of plasma renin activity, endothelin and aldosterone were carried out in individuals taking their usual diet, and after salt loading and salt depletion. RESULTS: Compared with the NARR group, patients in the HARR group had higher blood pressure, greater salt sensitivity of their blood pressure, significantly greater urine protein and lower serum potassium concentrations, lower renin activities [0.14 +/- 0.03 ng AngiotensinI (AI)/l per s compared with 0.76 +/- 0.16 ng AI/l per s; P < 0.005], blunted renin-aldosterone responses to salt loading and salt depletion, enhanced catecholamine responses to salt depletion, and increased plasma endothelin (5.1 +/- 0.5 fmol/ml compared with 3.7 +/- 0.3 fmol/ml; P < 0.03). In the HARR group, endothelin and aldosterone concentrations were highly correlated, and both correlated with blood pressure and urine protein. In contrast, in the NARR group, endothelin and aldosterone did not correlate between them or with blood pressure, and only endothelin, not aldosterone, correlated with urine protein. Multivariate regression confirmed that the interaction between aldosterone and endothelin was the major predictor of urine protein in the HARR group (r = 0.442), whereas endothelin, renin and their interaction were predictors in the NARR group (r = 0.467). CONCLUSIONS: Our results concur with experimental evidence for participation of endothelin in renal damage of angiotensin-dependent hypertension and for that of an endothelin-aldosterone interaction in low-renin hypertension. We propose that combined pharmacological antagonism of endothelin and aldosterone may confer renal protection beyond blood pressure reduction in patients with low-renin hypertension, a population at high risk for hypertensive nephrosclerosis.     

Management of Intra-Aortic Balloon Pump Entrapment: A Case Report and Review of the Literature

An intra-aortic balloon pump is one of the most valuable tools in the cardiac surgeon''s armament to assist in the management of the failing heart. Despite its widespread use, there are associated risks and complications, one of which is balloon rupture with associated entrapment. Numerous approaches for dealing with this complication have been described; here we review the previous experience with intra-aortic balloon pump entrapment and discuss potential management, with particular reference to a recent case of our own.Key words: Assisted circulation/adverse effects, counterpulsation/mortality, entrapment, intra-aortic balloon pumping/adverse effects/methods/mortality/rupture/standards/statistics & numerical data, risk assessmentCardiac surgery offers myriad interventions for possible use in an aging population that has a high prevalence of heart disease. This abundance of options has led to more complex cardiac surgery and to higher public expectations of successful outcomes.¹ Against this background, any mechanism that facilitates survival is welcome.The intra-aortic balloon pump (IABP), first used by Kantrowitz in 1967 in a patient with cardiogenic shock, provides mechanical cardiac support via insertion of an inflatable balloon into the descending aorta; it is the most commonly used supportive tool for temporary cardiac assistance.^1,2 The IABP works by reducing afterload and actively increasing coronary perfusion.² The indications are varied but include ongoing ischemia refractory to medical therapy, a need for prophylaxis in high-risk patients before cardiac surgery, and postoperative ischemia and low cardiac output despite inotropic support.³ Intra-aortic balloon pump use, although priceless in improving postoperative survival in high-risk cardiac surgical patients and those with ventricular dysfunction, is not without risks.^1,2 Balloon rupture, aortic or iliac artery dissection, thromboembolism, distal ischemia, and thrombocytopenia due to the mechanical action of the balloon on platelets are all potential complications of IABP use.^1,4 Despite these risks, there are over 70,000 insertions annually in the United States alone. Of all cardiac surgical patients, 5% to 10% undergo IABP placement.⁵ Intra-aortic balloon pump rupture with associated entrapment of the balloon within the arterial tree is very rare. Because numerous approaches to deal with this complication have been described, we review the previous experience and discuss the potential management of IABP entrapment, with specific reference to a case of our own.