Treatment of a coronary artery aneurysm with a novel stent

We report a case of a prominent aneurysm of the right coronary artery secondary to atherosclerotic coronary artery disease. The aneurysm was complicated by recurrent myocardial infarction despite optimal medical treatment. It was successfully treated with coronary artery stenting, using a novel device, consisting two stents with a layer of expandable graft material placed between them. Follow-up angiography 6 months after the procedure showed a sustained excellent result.

Brain natriuretic peptide increases acutely and much more prominently than atrial natriuretic peptide during coronary angioplasty

BACKGROUND

Increased levels of plasma brain natriuretic peptide (BNP) are observed in patients with congestive heart failure, hypertension, left ventricular hypertrophy, and acute myocardial infarction. However, there are no data on serial changes in plasma levels of BNP in patients undergoing coronary angioplasty.

HYPOTHESIS

The study was undertaken to examine plasma concentrations of BNP together with those of atrial natriuretic peptide (ANP) in patients undergoing percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Plasma concentrations of BNP and ANP were examined in 13 patients with stable angina pectoris and good left ventricular function undergoing PTCA. Blood samples were taken from the femoral vein at baseline, after the first balloon inflation, after the end of the procedure, and 4 h thereafter.

RESULTS

Plasma BNP levels were 14 +/- 4 at baseline, 22 +/- 10 after the first balloon inflation, 28 +/- 12 at the end of the procedure, and 15 +/- 4 pgr/ml 4 h thereafter (F = 13.05, p < 0.00001). Plasma ANP levels were 80 +/- 15, 86 +/- 14, 90 +/- 24, and 75 +/- 6 fmol/l (F = 5.95, p = 0.002), respectively. The increase of BNP at the end of the procedure was related to the increase of ANP (r = 0.78, p = 0.002).

CONCLUSION

Plasma BNP levels increase acutely and much more prominently than those of plasma ANP during coronary angioplasty; however, plasma BNP levels return to baseline values shortly after the end of the procedure.

Atrial natriuretic peptide augments coronary collateral blood flow: a study during coronary angioplasty

BACKGROUND AND HYPOTHESIS

In vitro studies have shown that atrial natriuretic peptide (ANP) causes relaxation of preconstricted blood vessel strips and inhibits the contraction of isolated vessels in response to norepinephrine and angiotensin II. The present study examined the effects of exogenous ANP on the coronary collateral blood flow during angioplasty.

METHODS

We studied 15 patients undergoing elective balloon angioplasty during the second and third balloon inflations. A Doppler flow guidewire was advanced distal to the lesion and used for the estimation of coronary blood flow velocity. After the second balloon inflation, 25 ng/kg/min of ANP were administered intracoronarily for 8 min. Electrocardiogram, pressure, and flow velocity were recorded immediately before each balloon deflation. Fourteen other patients served as controls and received normal saline infusion.

RESULTS

Velocity time integral increased from 65 +/- 40 to 79 +/- 46 mm (p < 0.05) during the third balloon inflation, whereas ST deviation decreased from 1.3 +/- 0.9 to 0.7 +/- 1.0 mV (p < 0.05). These variables did not change in the control group during the two tested balloon inflations.

CONCLUSION

Exogenous ANP augments coronary collateral blood flow and ameliorates myocardial ischemia during angioplasty.

Serum interleukin-6 is elevated in symptomatic carotid bifurcation disease

INTRODUCTION

The levels of circulating proinflammatory cytokines may express the extent of the inflammatory response and their participation in plaque progression and rupture needs to be evaluated. We aimed to investigate differences in circulating levels of proinflammatory cytokines and in plaque infiltration by macrophages between patients undergoing carotid endarterectomy for symptomatic and asymptomatic carotid atherosclerotic disease.

METHODS

One hundred nineteen patients (91 men and 28 women; mean age 66 +/- 8 years; range 42-83 years) who underwent carotid endarterectomy for significant (>70%) carotid bifurcation stenosis were enrolled in this study. Patients were characterized as symptomatic (n = 62) or asymptomatic (n = 57) after neurological examination. Serum levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), IL-1beta, serum amyloid A (SAA), and high-sensitivity C-reactive protein (hs-CRP) were evaluated. Macrophage infiltration of the plaque was assessed quantitatively from endarterectomy specimens using the monoclonal antibody CD68.

RESULTS

Serum IL-6 levels were significantly higher in patients with symptomatic compared with those with asymptomatic carotid disease (3.3 [2.0-6.5] pg/ml vs 2.5 [1.9-4.1] pg/ml, P = 0.02). TNF-alpha, IL-1beta, SAA, and hs-CRP levels did not differ significantly between the two groups. Symptomatic patients had also more intense macrophage accumulation in the carotid plaque compared with asymptomatic patients (0.6 +/- 0.1% vs 0.4 +/- 0.1%, P < 0.001). Although there were correlations between the levels of the different inflammatory markers, there were no correlation between any of them and the extent of plaque macrophage infiltration.

CONCLUSION

Patients with symptomatic carotid atherosclerotic disease have elevated serum IL-6 levels compared with asymptomatic patients. Symptomatic patients have also more intense macrophage infiltration of the atherosclerotic plaque suggesting that inflammatory process may contribute to the destabilization of the carotid plaque.

Bosentan in Eisenmenger syndrome and chronic thromboembolic pulmonary hypertension

BACKGROUND

Bosentan, a dual endothelin receptor antagonist, has been used for symptomatic improvement of patients with idiopathic pulmonary arterial hypertension (PAH) and specific types of secondary (e.g. scleroderma and human immunodeficiency virus infection) PAH, but its efficacy in patients with congenital heart disease and chronic thromboembolic pulmonary hypertension is still under evaluation. In this study two patients are presented, one with common atrioventricular canal and pulmonary hypertension and the other with recurrent pulmonary thromboembolism; both improved significantly after bosentan administration.

MATERIALS AND METHODS

The first patient was a 38-year-old female with trisomy 21, common atrioventricular canal and pulmonary hypertension (Eisenmenger syndrome). The second patient was a 57-year-old male, who was on anticoagulant therapy owing to an episode of pulmonary embolism that had been diagnosed 3 years earlier. Recurrent pulmonary thromboembolism was considered the most probable diagnosis. Chest spiral computed tomography examination excluded pulmonary endarterectomy as a therapeutic approach. At admission, the two patients were on New York Heart Association class IV, diagnosed by progressive rest dyspnea. Bosentan was administered to patients 1 and 2 for 6 and 9 months, respectively (62.5 mg b.i.d. for 4 weeks, then 125 mg b.i.d.).

RESULTS

Bosentan therapy resulted in significant clinical improvement in both patients. No hepatic dysfunction nor any other side-effect was observed.

CONCLUSIONS

Bosentan could be an effective therapy for pulmonary hypertension owing to congenital heart disease and chronic thromboembolic disease.

Early, intracoronary growth hormone administration attenuates ventricular remodeling in a porcine model of myocardial infarction

OBJECTIVE

Ventricular remodeling is a common corollary of myocardial infarction. We hypothesized that this process may be attenuated by growth hormone, administered as a single high-dose, selectively in the infarct zone, early postmyocardial infarction.

DESIGN

In 35 pigs (29+/-4 kg), myocardial infarction was generated by inflation of an over-the-wire angioplasty balloon in the circumflex artery for 60 min and 5 further pigs were sham-operated. Ten minutes after reperfusion, the pigs were randomized (2:1) to either growth hormone (1 IU/kg) (n=23) or normal saline (n=12), delivered via the balloon catheter. All survivors were treated with captopril and were sacrificed 4 weeks after myocardial infarction.

RESULTS

Compared to controls, growth hormone-treated animals displayed lower heart weight (4.1+/-0.5 g/kg body weight, versus 3.4+/-0.4 g/kg, respectively, p=0.003) and dimensions (left ventricular short axis diameter 46+/-7 mm versus 37+/-6 mm, p=0.01; right ventricular short axis diameter 38+/-7 mm versus 30+/-5 mm p=0.001). Growth hormone increased wall thickness in the infarct (6.0+/-1.8 in controls versus 9.9+/-3.7 in treated animals, p=0.004) and non-infarct zones (10.6+/-1.8 in controls versus 15.5+/-3.8 in treated animals, p=0.0006) and produced higher (p<0.05) microvascular density in both zones.

CONCLUSION

Intracoronary administration of growth hormone attenuates left and right ventricular remodeling by inducing hypertrophy and by enhancing angiogenesis.

Acute endothelin A receptor antagonism improves pulmonary and systemic haemodynamics in patients with pulmonary arterial hypertension that is primary or autoimmune and related to congenital heart disease

OBJECTIVE

To evaluate the acute haemodynamic effect of BQ-123, a selective endothelin A receptor antagonist, in severe chronic pulmonary arterial hypertension (PAH) of primary or autoimmune origin or related to congenital heart disease.

DESIGN

Prospective open clinical study.

SETTING

Cardiology tertiary referral centre.

PATIENTS

26 patients with chronic PAH were studied, with mean (SEM) age 29 (3) years (range 4-71 years), mean pulmonary artery pressure 68 (4) mm Hg, and pulmonary vascular resistance index 1694 (170) dyne x s x cm(-5). Patients were divided in three groups according to PAH aetiology: primary or autoimmune PAH (n = 12), and PAH associated with congenital heart defects with (n = 6) or without (n = 8) complete mixing.

INTERVENTION

BQ-123 200 nmol/min was infused for 60 minutes in the right atrium with sequential haemodynamic measurements at 30 minute intervals.

RESULTS

BQ-123 improved mean pulmonary artery pressure from 68 (4) to 64 (4) mm Hg (p < 0.05), pulmonary vascular resistance index from 1694 (170) to 1378 (145) dyne x s x cm(-5) (p < 0.001), pulmonary cardiac index from 3.0 (0.2) to 3.4 (0.3) l/min/m2 (p < 0.001), and effective cardiac index from 2.5 (0.2) to 2.7 (0.2) l/min/m2 (p < 0.01). Haemodynamic response was similar in all groups except for systemic cardiac index where a different (p = 0.0001, F = 5.53) response was observed; systemic cardiac index increased from 2.7 (0.2) to 2.9 (0.2) l/min/m2 (p < 0.001) when patients with complete mixing were excluded, in whom systemic cardiac index tended to decrease from 3.4 (1.0) to 3.0 (0.6) l/min/m2 (p = 0.06).

CONCLUSIONS

Acute endothelin A receptor antagonism induces substantial haemodynamic improvement in severe chronic PAH of primary or autoimmune origin or related to congenital heart disease.

Haemodynamic and catecholamine response to simulated ventricular tachycardia in man: effect of baseline left ventricular function

OBJECTIVE

To examine the effects of baseline left ventricular function on the haemodynamic and catecholamine responses to ventricular tachycardia.

DESIGN

Experimental cohort study.

SETTING

Cardiac catheterisation laboratory in tertiary referral centre.

SUBJECTS

24 patients (19 male, 5 female; mean (SD) age, 59 (10) years) without coronary artery disease, divided into two groups with normal or impaired left ventricular function: group A, ejection fraction > 65% (n = 10); group B, ejection fraction < 45% (n = 14). Other medical and demographic factors were similar in the two groups.

INTERVENTIONS

Ventricular tachycardia was simulated with rapid pacing at 150 beats/min for 10 minutes.

MAIN OUTCOME MEASURES

Arterial blood pressure; venous plasma catecholamine concentrations.

RESULTS

During rapid pacing, blood pressure was lower in group B (with impaired left ventricular function) than in group A: systolic blood pressure, 102 (11) v 115 (9) mm Hg (p = 0.005); mean blood pressure, 79 (6) v 85 (6) mm Hg (p = 0.02). The ejection fraction correlated with the lowest systolic blood pressure (r = 0.64, p = 0.0006). Although the rise in adrenaline was comparable between the two groups, the rise in noradrenaline was more pronounced (p < 0.05) in patients in group B.

CONCLUSION

At low rates and in selected patients, the underlying state of left ventricular function affects haemodynamic tolerance of ventricular tachycardia. Patients with impaired left ventricular function have a lower blood pressure during ventricular tachycardia, despite an exaggerated noradrenaline release.

Type II diabetes does not prevent the recruitment of collateral vessels and the normal reduction of myocardial ischaemia on repeated balloon inflations during angioplasty

OBJECTIVE

To test whether type II diabetes prevents the recruitment of collaterals and the normal reduction of myocardial ischaemia on repeated balloon inflations during coronary angioplasty.

METHODS

Two groups of patients were studied. A collateral circulation group consisted of 56 patients, 18 diabetic and 38 non-diabetic. All underwent a minimum of three balloon inflations. A pressure guide wire was used for the measurement of coronary wedge pressure (mm Hg). The angioplasty protocol was repeated in another group of 57 patients (myocardial ischaemia group) using both surface and intracoronary ECGs to assess myocardial ischaemia.

RESULTS

In diabetic patients, mean (SD) coronary wedge pressure was 35 (12) mm Hg during the first balloon inflation, 39 (15) mm Hg during the second (p < 0.05 v first inflation), and 42 (17) mm Hg during the third (p < 0.05 v first inflation); in non-diabetic patients the respective values were 36 (16), 37 (16), and 37 (16) mm Hg (F = 4.73, p = 0.01). The ratio of coronary wedge pressure to mean arterial pressure in diabetic patients in the three balloon inflations was 0.33 (0.11), 0.36 (0.13), and 0.39 (0.15), respectively (p < 0.05 v the first inflation); and in non-diabetic patients it was 0.33 (0.15), 0.34 (0.15), and 0.35 (0.15) (F = 1.92, p = 0.15). In the diabetic group the response was independent of the type of treatment. No difference between diabetic and non-diabetic patients was observed in the normal reduction of myocardial ischaemia on repeated balloon inflations.

CONCLUSIONS

Type II diabetes does not prevent the recruitment of collateral vessels and the normal reduction of myocardial ischaemia on repeated balloon inflations during coronary angioplasty in single vessel disease, regardless of the type of antidiabetic treatment.

Intramuscular administration of estrogen may promote angiogenesis and perfusion in a rabbit model of chronic limb ischemia

OBJECTIVE

Promoting angiogenesis may be an effective treatment for patients with diffuse peripheral vascular disease. This study investigated whether estrogen can promote angiogenesis and perfusion in a rabbit model of chronic limb ischemia.

METHODS AND RESULTS

Ischemia was induced in one hindlimb of 24 oophorectomized New Zealand White rabbits. Ten days later (day 0), they were randomized into 4 groups for intramuscular treatment in the ischemic limb: controls receiving saline at day 0; Estrogen-1 group receiving estradiol valerate, modified release (EVMR), 1 mg/kg at day 0; Estrogen-2 group receiving EVMR 1 mg/kg at days 0 and 15; and Estrogen-3 group receiving EVMR 2 mg/kg at day 0. Revascularization was evaluated by clinical indexes, such as ischemic/normal limb systolic blood pressure (BPR), and capillary density/muscle fiber in the abductor muscle of the ischemic limb at the time of death (day 30). At day 30 the BPR was increased in all groups (0.39+/-0.08 in the controls, 0.52+/-0.11 in the Estrogen-1 group, 0.65+/-0.13 in the Estrogen-2 group and 0.61+/-0.16 in the Estrogen-3 group, F=2.39, P=0.04). The capillary/muscle fiber at day 30 was 0.87+/-0.09, 1.08+/-0.15, 1.01+/-0.14 and 1.10+/-0.9 (F=5.01, P=0.01), respectively, in the 4 groups. The capillary/muscle fiber was related to BPR (r=0.48, P<0.02) and to 17-beta estradiol plasma levels of day 15 (r=0.58, P=0.003) and of day 30 (r=0.46, P<0.02).

CONCLUSION

Administration of estrogen promotes angiogenesis and perfusion in ischemic rabbit hindlimbs. Thus, estrogen may represent a new therapeutic modality in the management of arterial insufficiency.

Serial evaluation of coronary flow reserve by transesophageal doppler echocardiography after angioplasty of proximal left anterior descending coronary artery: a 6-month follow-up study

BACKGROUND

Coronary flow reserve can be estimated by transesophageal Doppler echocardiography (TDE).

OBJECTIVE

To evaluate the coronary flow reserve by TDE, serially over 6 months' follow-up, after successful percutaneous transluminal coronary angioplasty (PTCA) of proximal left anterior descending coronary artery (LADA).

METHODS AND RESULTS

We performed TDE examination of 30 patients (mean age 55 +/- 9 years) 72 h, 3 months, and 6 months after PTCA of LADA. Selective angiography of LADA was repeated 72 h and 6 months after PTCA of LADA. Velocity of flow in LADA was measured before and 2 min after cessation of intravenous infusion of dipyridamole (0.56 mg/kg in 4 min). The dipyridamole: rest mean diastolic velocity ratio was considered as an index of coronary flow reserve (CFR). For 20 of 21 patients with CFR > 2 there was no restenosis, whereas coronary angiography revealed restenosis in eight of nine patients with CFR < 2. The sensitivity was 88.9% and the specificity was 95.2%. For the 21 patients without restenosis mean CFR was 2.1 +/- 0.1 72 h after PTCA, had increased to 3.1 +/- 0.3 (P < 0.0001) 3 months after PTCA, and remained stable thereafter (3.0 +/- 0.9).

CONCLUSION

CFR after PTCA of proximal LADA can be evaluated serially by transesophageal Doppler echocardiography. CFR of LADA in patients without restenosis is increased 3 months after PTCA and remains stable thereafter.

Multicenter evaluation of the phosphorylcholine-coated biodivYsio stent in short de novo coronary lesions: The SOPHOS study

AIMS: The BiodivYsio trade mark stent (Biocompatibles Ltd, Farnham, UK) is coated with a phosphorylcholine (PC)-containing copolymer to confer biocompatibility. The SOPHOS (Study Of PHosphorylcholine coating On Stents) study was designed to assess the safety and efficacy of this novel coronary stent and by indirect comparison to indicate equivalence with other formal stent studies. METHODS AND RESULTS: Patients with angina and a single short (#x2A7F;12 mm) de novo lesion in a native coronary artery of >/=2.75 mm diameter were included. A total of 425 patients were allocated in 24 centers. Clinical data were collected at one-, six- and nine-month follow-up. Angiography was performed before and after the stent implantation. In addition, in the first 200 patients (SOPHOS A) angiography was routinely performed at six months. The following 225 patients (SOPHOS B) were merely followed up clinically. The primary end-point of the study, the six-month MACE-rate (MACE = Major Adverse Cardiac Events) was 13.4% (two cardiac death; five Q-wave/nine non-Q-wave myocardial infarctions (MI); nine CABG and 32 target lesion revascularization (TLR), which is similar to the calculated 15% MACE-rate in comparable reference studies. Secondary end-points included among others restenosis at six months in the SOPHOS A population. The target vessel diameter was 2.98 +/- 0.48 mm. Minimal lumen diameter pre/post procedure and at follow-up was 1.00 +/- 0.32, 2.69 +/- 0.37, 1.91 +/- 0.71 mm, respectively. The binary restenosis rate (>/=50% diameter stenosis at follow-up) was 17.7%. CONCLUSION: The coronary BiodivYsio stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with stable or unstable angina pectoris. Clinical and angiographic results are in the statistical range of equivalence with comparable studies with other current stents.

Acute endothelin-A receptor antagonism prevents normal reduction of myocardial ischemia on repeated balloon inflations during angioplasty

BACKGROUND

Myocardial ischemia and reperfusion are associated with increased production of endothelin (ET)-1.

METHODS AND RESULTS

We examined the effects of BQ-123, a selective ET(A) receptor antagonist, in 80 patients. All patients were randomly allocated to an intracoronary infusion of saline or BQ-123 (6 micromol/L over 20 minutes). The reference group consisted of 20 patients undergoing coronary angiography. BQ-123 produced a 10% (P:<0.005) increase in distal coronary artery diameter. The main study group consisted of 30 patients undergoing coronary angioplasty. All patients underwent a minimum of 3 balloon inflations (BIs). Surface and intracoronary electrocardiographic ST-segment shift as well as pain score were recorded at the end of each BI. BQ-123 or saline was given by intracoronary infusion between the second and the third BI in random allocation. In the saline group, intracoronary ST-elevation decreased from 1.26+/-0.55 mV during the first BI to 0.77+/-0.56 mV during the third BI (P:<0.05) and the surface ST elevation decreased from 0.20+/-0.15 to 0.10+/-0.07 mV (P:<0.05). In the BQ-123 group, the respective values were 1.22+/-0.48 mV and 1.13+/-0.62 mV (intracoronary) and 0.17+/-0.18 and 0.17+/-0.21 mV (surface) (both P:=NS). The decrease in pain score was significantly higher in the saline group (F:=5.97, P:=0.004). In 30 patients (collateral circulation group), the angioplasty protocol was repeated with the use of a pressure guide wire. BQ-123 produced a significant (F:=3.30, P:=0.04) decrease in coronary wedge pressure.

CONCLUSIONS

Acute ET(A) receptor antagonism prevents the normal reduction of myocardial ischemia on repeated BIs during angioplasty. This may be explained by a "steal" effect through coronary collaterals.

Endogenous endothelin maintains coronary artery tone by endothelin type A receptor stimulation in patients undergoing coronary arteriography

OBJECTIVE

To examine the contribution of endothelin type A (ET(A)) receptor stimulation by endogenously generated endothelin-1 (ET-1) to the maintenance of coronary vascular tone in humans.

DESIGN

Controlled clinical study.

SETTING

Tertiary cardiovascular referral centre.

PATIENTS

14 subjects were studied, seven with normal coronary arteries and seven with coronary artery disease, mean (SEM) age, 53 (2) years.

INTERVENTIONS

After diagnostic coronary arteriography, BQ-123 (a selective ET(A) receptor antagonist; 100 nmol/min) in 0.9% saline, was infused into the left coronary artery at a rate of 1 ml/min for 60 minutes. Eight control subjects received saline alone.

MAIN OUTCOME MEASURES

Blood flow velocity in the left anterior descending coronary artery, measured using a Doppler flow guidewire; coronary arteriography performed at baseline and immediately at the end of the BQ-123 or saline infusion to measure the diameter of proximal and distal left anterior descending coronary artery segments.

RESULTS

The diameter of the proximal segment increased by 6 (2)%, while that of the distal segment increased by 12 (3)% after BQ-123 (both p < 0.05 v baseline). Coronary blood flow increased from 75 (10) to 92 (10) ml/min and coronary vascular resistance decreased from 1.99 (0.36) to 1.44 (0. 22) mm Hg/ml/min after BQ-123 (both p < 0.05 v baseline). The response to BQ-123 of patients with and without coronary artery disease was similar. There was no effect of saline in the controls.

CONCLUSIONS

Endogenously produced ET-1 contributes to the maintenance of basal coronary artery tone in humans by ET(A) receptor stimulation. The role of ET(B) receptors remains to be defined.

Cell adhesion molecules in relation to simvastatin and hormone replacement therapy in coronary artery disease

AIMS

To assess the effect of simvastatin, hormone replacement therapy and their combination on soluble cell adhesion molecules and plasma lipids, in hypercholesterolaemic post-menopausal women with coronary artery disease.

METHODS

We studied 16 post-menopausal women with coronary artery disease and hypercholesterolaemia (total cholesterol >200mg x dl(-1) and LDL cholesterol >130 mg x dl(-1)). We compared simvastatin (20 mg daily) with hormone replacement therapy (0.625 mg conjugated oestrogen and 2.5 mg medroxyprogesterone acetate daily) and their combination, in a randomized, crossover, placebo controlled study. Each treatment period was 8 weeks long with a 4 week washout interval between treatments. Circulating cell adhesion molecules and plasma lipids were evaluated at the end of each treatment period.

RESULTS

All three active treatments--simvastatin, hormone replacement therapy and the combination therapy--significantly reduced total and LDL cholesterol, compared to placebo (P<0.001). Only hormone replacement therapy, alone and in combination with simvastatin, significantly decreased lipoprotein(a) when compared to placebo (P<0.05), whereas simvastatin had no significant effect. Likewise, hormone replacement therapy and the combination therapy significantly reduced the intercellular adhesion molecule (ICAM-1) plasma levels (P=0.03 and P=0.02, respectively), while simvastatin, which was superior to hormone replacement therapy in lowering total and LDL cholesterol, did not modify ICAM-1 levels; the combination therapy was not more effective than hormone replacement therapy alone in ICAM-1 reduction. Neither the effect, on any treatment when compared to placebo, of VCAM-1 nor E-selectin levels differed significantly.

CONCLUSIONS

Hormone replacement therapy may limit the inflammatory response to injury by modulating the expression of cell adhesion molecules from the endothelial cells, possibly in association with lipoprotein (a) reduction.

Improved left ventricular relaxation during short-term right ventricular outflow tract compared to apical pacing

STUDY OBJECTIVES

Pacing-induced asynchrony may deteriorate left ventricular function; however, limited data exists in humans. The aim of our study was to compare left ventricular hemodynamics during short-term atrioventricular sequential pacing from the right ventricular apex and from the outflow tract of the right ventricle.

DESIGN

Three 5-min pacing intervals were applied in a random order, at a rate of 15 beats/min above the resting sinus rate. Atrioventricular sequential pacing from the two sites was compared with atrial pacing. During each pacing mode, left ventricular pressure was recorded, and cardiac output was calculated using Doppler echocardiography.

SETTING

Cardiac catheterization laboratory.

PATIENTS

Twenty patients (18 male, mean age 62 +/- 11 years) without structural heart disease were studied.

RESULTS

During atrial pacing, maximum negative first derivative of pressure (dp/dt) was 1,535 +/- 228 mm Hg/s; during pacing from the apex it decreased to 1,221 +/- 294 mm Hg/s (p = 0.0001), but was not significantly different during pacing from the outflow tract (1,431 +/- 435 mm Hg/s, p > 0.05). Isovolumic relaxation time constant (tau) during atrial pacing was 39.7 +/- 11.9 ms; during pacing from the apex, it increased to 47.9 +/- 14.0 (p = 0.001), but was not significantly different during pacing from the outflow tract (42.5 +/- 11.2, p > 0.05). Peak systolic pressure decreased significantly during atrioventricular sequential pacing from either site; however, it did not differ between the two sites. No differences in end-diastolic pressure, maximum positive dp/dt, or cardiac output could be demonstrated.

CONCLUSION

In patients with no structural heart disease, short-term right ventricular outflow tract pacing is associated with more favorable diastolic function, compared to right ventricular apical pacing.

Intracoronary ketanserin augments coronary collateral blood flow and decreases myocardial ischemia during balloon angioplasty

AIMS

To test the hypothesis that ketanserin augments coronary collateral blood flow and decreases myocardial ischemia during balloon angioplasty.

METHODS AND RESULTS

Forty-four patients with single vessel disease and stable angina were studied. Collateral flow was determined during balloon inflations, based on the distal velocity time integral (13 patients) or on coronary wedge/mean arterial pressure measurements (10 patients). The 2nd and 3rd inflations lasted the same time and between them 1.5 mg intracoronary ketanserin in 10 ml normal saline was administered over 3 min. In 21 control subjects normal saline alone was given. In the flow velocity group the velocity time integral was 78.5+/-53.1 mm during the 2nd inflation and 106.0+/-43.2 mm during the 3rd (p<.05), while the ST deviation was 1.1+/-.7 and .7+/-.7 mm, respectively (p<.05). In the intracoronary pressure group the CWP/MBP was .40+/-.10 during the 2nd inflation and .45+/-.11 during the 3rd (p<.05), while the ST deviation was 1.2+/-.8 and .8+/-.8 mm respectively (p<.05). In the controls no variables changed during the tested inflations.

CONCLUSION

Intracoronary administration of ketanserin augments coronary collateral flow and decreases myocardial ischemia during balloon angioplasty. This could be of clinical significance in the management of acute ischemic syndromes.

Importance of the site of ventricular tachycardia origin on left ventricular hemodynamics in humans

Experimental animal data have indicated that the site of ventricular tachycardia origin and, hence, the degree of asynchronous contraction, may influence the hemodynamic tolerance during sustained ventricular tachycardia. However, data in man are scarce. We studied patients with preserved left ventricular function and absence of significant coronary artery disease. Ventricular tachycardia was simulated with rapid pacing (at 120 and 150 beats/min), performed randomly, from the right ventricular apex or the right ventricular outflow tract. Following pacing from one site, it was repeated from the alternate site. Compared to outflow tract pacing, QRS duration was significantly longer during rapid pacing from the apex. Left ventricular pressure was recorded using a micromanometer-tipped catheter. During sinus rhythm, peak systolic pressure was 142 +/- 14 mmHg; at 120 beats/min, it decreased to 109 +/- 12 mmHg during pacing from the apex and to 127 +/- 21 mmHg during pacing from the outflow tract (P = 0.008). This difference diminished at 150 beats/min (101 +/- 16 mmHg vs 112 +/- 16 mmHg, respectively, P = 0.21). During sinus rhythm end-diastolic pressure was 13 +/- 1 mmHg, which did not change significantly during pacing at 120 beats/min. During pacing at 150 beats/min, end-diastolic pressure increased to 21 +/- 3 mmHg during pacing from the apex and to 16 +/- 2 mmHg during pacing from the outflow tract (P = 0.005). Changes in first derivative of pressure and in isovolumic relaxation time constant were comparable during pacing from the two sites. Thus, it seems that tachycardias originating from the right ventricular outflow tract result in more favorable left ventricular hemodynamics, compared to those from the right ventricular apex.

Cardiac pacing and coronary hemodynamics

This article reviews the current knowledge on the effects of pacing on coronary hemodynamics. In particular, the possible effects of heart rate, atrioventricular delay, ventricular depolarization sequence, and ventricular pacing site on the coronary circulation are examined.

Beta-adrenergic blockade decreases coronary collateral blood flow in patients with coronary artery disease

The effect of beta-adrenergic blockade on coronary collateral blood flow has not been clarified. We examined the acute effects of beta-adrenergic blockade on coronary collateral blood flow. Fifteen patients (Part A) with stable angina were studied while undergoing coronary angioplasty. According to the protocol, all patients underwent a minimum of three balloon inflations. Collateral flow velocity was determined during balloon inflations using the Doppler flow guidewire positioned distally to the lesion. The two tested balloon inflations, the second and third, were maintained for the same length of time. Between the second and third balloon inflations, 1 mg of propranolol was administered IC into the treated artery. Ten controls were studied following saline infusion. In 10 other patients (Part B), the effect of 1 mg IC propranolol on the coronary artery area distal to the lesion was studied, and five patients served as controls. In the treated group, in Part A blood pressure remained stable during the balloon inflations tested. Heart rate decreased from 79 +/- 11 to 73 +/- 12 beats/min (P < .05), velocity time integral from 9.6 +/- 8.2 to 6.6 +/- 4.1 cm (P < .05), and ST elevation from 1.3 +/- .9 to .9 +/- 1.0 mV (P < .05) between the second and third balloon inflations. In the controls the variables examined did not change during the balloon inflations tested. In Part B, neither propranolol nor normal saline had any significant effect on coronary artery lumen area. Thus, IC administration of beta-adrenergic blockade decreases coronary collateral blood flow, and this potentially worsens the ischemic zone. However, beta-adrenergic blockade ameliorates myocardial ischemia during coronary angioplasty.

The effect of hormone replacement therapy alone and in combination with simvastatin on plasma lipids of hypercholesterolemic postmenopausal women with coronary artery disease

OBJECTIVES

This study sought to compare hormone replacement therapy (HRT), simvastatin and their combination in the management of hypercholesterolemia in postmenopausal women with coronary artery disease (CAD).

BACKGROUND

Lipid-lowering therapy reduces mortality in hypercholesterolemic women with CAD. In postmenopausal women HRT seems to increase survival, particularly those with ischemic heart disease, and this is partly due to changes in lipid levels.

METHODS

We studied 16 postmenopausal women with CAD and fasting total cholesterol <200 mg/dl and low-density lipoprotein (LDL) cholesterol <130 mg/dl. We compared HRT (0.625 mg of conjugated estrogen and 2.5 mg of medroxyprogesterone acetate daily) with simvastatin (20 mg daily) and their combination in a randomized, crossover, placebo-controlled study. Each treatment period was 8 weeks long with a 4-week washout interval between treatments.

RESULTS

Simvastatin, HRT and their combination significantly reduced total and LDL cholesterol by 35%, 13%, and 33% and 45%, 20%, and 46%, respectively, compared to placebo (p < 0.001). However, simvastatin and the combination was superior to HRT (p < 0.001), and none of our patients had total cholesterol <180 mg/dl and LDL cholesterol <100 mg/dl on HRT alone. High-density lipoprotein cholesterol was not significantly affected by any of the active treatments, and triglycerides were lower during simvastatin therapy compared to placebo (p < 0.01). Apolipoprotein B was significantly reduced by simvastatin, alone and combined with HRT, by 39% and 35%, respectively, compared to placebo (p < 0.001). Alone and in combination with simvastatin, HRT significantly increased apolipoprotein A-I by 11% and 12%, respectively, compared to placebo (p < 0.05) and decreased lipoprotein (a) by 23% and 33%, respectively, compared to placebo (p < 0.05), whereas simvastatin had no significant effect on either of these parameters.

CONCLUSIONS

In hypercholesterolemic postmenopausal women with CAD, HRT exerts beneficial effects on plasma lipids but the levels currently recommended for secondary prevention are not achieved. Hormone replacement therapy combined with simvastatin is well tolerated and extremely effective, as the two therapies seem to be additive.

Absence of effects of short-term estrogen replacement therapy on resting and exertional QT and QTc dispersion in postmenopausal women with coronary artery disease

Women, on average, have a longer QT interval on the electrocardiogram and are at higher risk of developing torsade de pointes from antiarrhythmic therapy than men. Although endogenous estrogen may play a role in these sex differences, the effect of estrogen replacement therapy has not been examined. Ten women, 65 +/- 7 years of age, with stable angina pectoris, positive exercise test, and angiographically proven coronary artery disease (at least one > or = 70%) stenosis were studied. All women had been postmenopausal for at least 1 year, and none had ever received hormone replacement therapy (HRT). The patients received standard dose HRT (0.625 mg/day oral conjugated estrogen) or matching placebo for 4 weeks in random order, with crossover after a 4-week washout period. Exercise testing using the standard Bruce protocol was performed at the end of the first and third months of the study. Antianginal medications remained unchanged throughout the study period. Compared to placebo, HRT caused a significant increase in plasma estradiol levels from 5.55 +/- 1.66 to 31.11 +/- 14.95 pg/mL (P = 0.001). QT and QTc, as well as QT and QTc dispersion, did not differ at rest and at peak exercise between the two exercise tests. Likewise, other test results, including angina score, exercise time, ST-T changes, blood pressure, heart rate, and double product were unchanged. Short-term HRT did not alter cardiac repolarization at rest and during exercise in postmenopausal women with known coronary disease.

Coronary flow reserve in the contralateral artery increases after successful coronary angioplasty in patients with spontaneously visible collateral vessels

OBJECTIVE

To test the hypothesis that coronary flow reserve could increase in the angiographically normal contralateral artery after successful coronary angioplasty of an ipsilateral coronary artery.

DESIGN

Coronary flow reserve was estimated using a Doppler flow guide wire, by giving intracoronary adenosine in the contralateral artery, before and 15 minutes after the end of angioplasty.

SETTING

Tertiary referral centre.

PATIENTS

31 patients, mean (SD) age 56 (11) years, with stable angina and single vessel disease, undergoing angioplasty of the right coronary or the left anterior descending artery.

RESULTS

In the contralateral artery baseline average peak velocity was 21 (9) cm/s before angioplasty and decreased to 12 (6) cm/s after (p < 0.005), while hyperaemic average peak velocity was 47 (19) cm/s before and decreased to 34 (15) cm/s after (p < 0.005). However, coronary flow reserve in the contralateral artery was 2.4 (0.7) before angioplasty and increased to 2.9 (0.6) after (p < 0.05). The contralateral coronary flow reserve after angioplasty increased by 0.8 (0.4) in 11 patients with visible collaterals before angioplasty and by 0.3 (0.6) in the remaining patients without visible collaterals (p < 0.05). Blood pressure and heart rate were unchanged after the procedure.

CONCLUSIONS

Coronary flow reserve in an angiographically normal contralateral artery increases after successful coronary angioplasty of the ipsilateral artery in patients with spontaneously visible collateral vessels before the procedure.

Short-term estrogen reduces myocardial infarct size in oophorectomized female rabbits in a dose-dependent manner

17 beta-estradiol, administered acutely, protects ischemic myocardium in male rabbits. In the present study we investigated the effect of short-term estrogen on myocardial infarct size in oophorectomized female rabbits. We oophorectomized 24 sexually mature New Zealand white female rabbits. Twelve animals were left untreated and 12 received oral conjugated estrogens, 0.15 mg/day, for 4 weeks. At a second stage, a third group of 12 oophorectomized female rabbits was treated with intramuscular conjugated estrogens, 1 mg/day, also for 4 weeks. All rabbits underwent 30 minutes of coronary artery occlusion and 2 hours of reperfusion while on anesthesia with i.v. pentobarbital. Infarct and risk area were delineated by Zn-Cd fluorescent particles and tetrazolium chloride staining. The infarct size was expressed as a percentage of the risk zone (I/R %). Data are reported on 26 animals that survived the treatment period and the experiment. Heart rate, systolic, and mean blood pressure and double product did not differ between the three groups at baseline, ischemia, and reperfusion. The infarct size of the risk zone was significantly smaller in the intramuscular group compared with both the oral and the placebo group (18.5 +/- 3.5% vs. 41.3 +/- 9.2% and 43 +/- 8.4%, respectively, P = 0.03). Conjugated estrogens, administered intramuscularly at a high dose, protect ischemic myocardium in oophorectomized female rabbits.

Coronary blood flow velocity during apical versus septal pacing

Previous studies have indicated that ventricular asynchrony may significantly affect resting coronary blood flow velocity. Our study argues against this hypothesis, as comparable left anterior descending blood flow velocities were found during three pacing modalities, associated with varying degrees of asynchrony: (a) atrial pacing, (b) atrioventricular (AV) sequential pacing from the right ventricular apex and (c) AV sequential pacing from the proximal right ventricular septum.

Effect of rotational coronary atherectomy on peripheral endothelin-1, atrial natriuretic peptide, and cyclic adenosine monophosphate plasma levels

We investigated the effects of coronary rotational atherectomy (PTCRA) on plasma levels of endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and cyclic adenosine monophosphate (cAMP). We studied 14 patients undergoing PTCRA and compared them with 14 patients undergoing plain balloon angioplasty. Blood samples were taken from the femoral vein at baseline, after the end of the atherectomy, after the first balloon inflation, after the end of the procedure, and 4 hours later. ET-1 increased in the angioplasty group from 6.3 +/- 3.2 pmol/L at baseline to 8.5 +/- 3.9 pmol/L at the end of the procedure (F = 3.83, P = .02), whereas it did not change in the PTCRA group. ANP increased in the PTCRA group from 78.1 +/- 15.7 pmol/L at baseline to 89.7 +/- 24.0 pmol/L at the end of the procedure (F = 6.75, P = .0001), whereas it did not change in the angioplasty group. cAMP decreased in the PTCRA group, whereas it did not change in the angioplasty group. In conclusion, ET-1 increases less, ANP increases more, and cAMP decreases more during atherectomy than during plain balloon angioplasty.

Coronary blood flow changes during atrioventricular sequential pacing with different atrioventricular delays in normal individuals

This study examined the effects of different atrioventricular (AV) intervals, during AV sequential pacing, on hemodynamics and coronary blood flow in individuals with normal hearts. Left anterior descending artery blood flow velocity was measured, using intracoronary Doppler, in 17 normal individuals. Five pacing tests were applied in random order for 5 min, at 15 beats/min above the sinus rate. Four tests using AV sequential pacing with AV intervals of 175, 150, 100, and 50 ms, and one using atrial pacing were applied. Mean flow velocity was 21 +/- 9 cm/s, 20 +/- 9 cm/s, 17 +/- 7 cm/s, 17 +/- 7 cm/s, and 22 +/- 10 cm/s, respectively (F = 8.87, p = .00001). The hemodynamic effects of these 5 pacing tests were assessed in 8 different normal subjects. Isovolumic relaxation time constant and left ventricular systolic pressure decreased, whereas right atrial pressure increased during AV sequential pacing with short AV intervals. Thus, during short-term AV sequential pacing at rest, coronary blood flow in a normal left anterior descending artery decreases with short AV intervals.

Short-term atrioventricular sequential pacing does not adversely affect collateral blood flow: a study during angioplasty

Altered sequence of ventricular activation sequence results in marked derangements in mechanical events. In the present study, we investigated the comparative effects of atrial and AV sequential pacing on collateral blood flow during angioplasty. Twenty-eight patients with stable angina and left anterior descending artery disease undergoing balloon angioplasty were studied. Collateral flow was determined during balloon inflation from the distal flow velocity of the ipsilateral artery (17 patients) or from the increase of the maximal diastolic blood flow velocity (Vc) of the contralateral artery (11 patients). Flow measurements were made using the Doppler flow guidewire. The relative resistance in the collateral vascular bed (RR) also was estimated in the latter group of patients. After the first balloon inflation, two similar consecutive balloon inflations were done under atrial and AV sequential pacing, at a rate of 15 beats/min higher than the sinus rate, in the absence of vasoactive medication. One minute after the initiation of pacing, the second and third balloon inflations were begun and the pacing continued until the balloon inflations were completed. In the ipsilateral group, average peak velocity was 84.6 +/- 24.2 mm/2 during atrial pacing and 82.7 +/- 29.7 mm/s during AV sequential pacing (P = NS). In the contralateral group, Vc was 18% +/- 12% during atrial pacing and 17% +/- 14% during AV sequential pacing, and the RR was 4.5 +/- 4.7 and 4.9 +/- 6.4, respectively (both P = NS). The coronary wedge/mean blood pressure was similar during the two tested balloon inflations. Short-term AV sequential pacing at rest does not adversely affect collateral blood flow and resistance in patients with left anterior descending artery disease.

Transesophageal Doppler evaluation of left anterior descending coronary artery angioplasty

Transesophageal Doppler echocardiography can noninvasively evaluate the functional results of left anterior descending coronary artery angioplasty. Coronary flow reserve assessed by this technique is significantly increased only in those patients with less severe residual stenosis as detected by intravascular ultrasound, thus allowing a noninvasive assessment of the results of left anterior coronary artery angioplasty.

Acute hemodynamic effects of estrogen administration in postmenopausal women

The hemodynamic effects of estrogens in replacement doses have not been fully clarified; therefore, we studied the acute hemodynamic changes after 0.625 and 1.25 mg of conjugated estrogens, administered intravenously, using a thermodilution catheter, in postmenopausal women without structural heart disease. Pulmonary and systemic pressures and resistances and stroke volume did not change compared with baseline, but heart rate and cardiac output decreased significantly, which may be associated with estrogen's previously described calcium-blocking effect or with a more recently contemplated beta-blocking action.

Atrioventricular pacing does not increase infarct size in the in situ rabbit heart

OBJECTIVE

To examine the hypothesis that an altered left ventricular depolarization sequence may augment infarct size.

METHODS

Twenty-one New Zealand male rabbits were anesthetized and ventilated. The chest was opened and two electrodes were placed on the right atrium and ventricle. The rabbits were then randomized to atrial (n = 7), atrioventricular (AV) sequential (n = 7) or no (n = 7) pacing. The pacing rate was 20 beats/min higher than the sinus rate. After 1 min of pacing, the left coronary artery was occluded by a snare. After 30 mins, the snare was released and pacing was stopped. After 120 mins of reperfusion the experiment was terminated. Normal areas and areas at risk were delineated, infarct size was measured and the infarcted areas and areas at risk were planimetered.

RESULTS

All results were expressed in cubic centimetres, and the ratio of the infarcted area to area at risk was calculated as a percentage (%I:R). The double product during ischemia was 21,546 +/- 2300 in controls, 23,000 +/- 3005 in rabbits with atrial pacing and 24,418 +/- 4253 in rabbits with AV pacing (F = 1.33, P = 0.28), and %I:R was 41.4 +/- 19.8, 43.9 +/- 15.4 and 38.4 +/- 18.4 (F = 0.16, P = 0.84), respectively.

CONCLUSIONS

An altered left ventricular depolarization sequence in rabbit hearts does not increase infarct size.

Coronary collateral blood-flow velocity improves with repeated coronary occlusions during angioplasty in patients with coronary artery disease and systemic hypertension

BACKGROUND

Cardiac hypertrophy is associated with numerous alterations in the coronary circulation.

OBJECTIVE

To test the hypothesis that, during angioplasty, the coronary collateral blood flow during repetitive coronary occlusions increases more in hypertensives than it does in normotensives.

METHODS

We studied 34 patients (22 normotensives and 12 hypertensives) with stable angina and single-vessel disease undergoing coronary angioplasty during two similar balloon inflations. Each balloon inflation was maintained for 120 s. The coronary blood flow velocity was estimated using the Doppler-flow guide wire, which was positioned distally to the lesion. Flow velocities were recorded before balloon deflation.

RESULTS

The average peak velocity increased by 29.0 +/- 14.7 mm/s in the hypertensives and decreased by 9.4 +/- 4.9 mm/s in the normotensives (P < 0.01) during the second balloon inflation, whereas the velocity-time integral increased by 33.1 +/- 19.2 mm and decreased by 14.3 +/- 11.3 mm (P < 0.05), respectively. The ST-segment elevation decreased by 1.13 +/- 1.27 and by 0.17 +/- 0.16 mV, respectively (P = 0.01). The increase in the average peak velocity which occurred during the second balloon inflation was related to the left ventricular mass (r = 0.47, P = 0.004).

CONCLUSION

These results indicate that the coronary collateral blood flow velocity improves with repetitive coronary occlusions during angioplasty in patients with systemic hypertension and that this increase is correlated to the left ventricular mass.

Coronary flow reserve assessed by transesophageal echocardiography identifies early restenosis of the left anterior descending coronary artery angioplasty

Although an increase in diastolic coronary flow velocity can be detected by transesophageal echocardiography 72 hours after both successful and unsuccessful left anterior coronary artery angioplasty, a significant improvement in coronary flow reserve is observed only in patients with a successful procedure. Transesophageal echocardiography-derived coronary flow reserve can identify early restenosis and thus serve as an index of the outcome of the procedure.

Effect of intracoronary estrogen on coronary collateral blood flow velocity

The effect of estrogen on collateral circulation has not been previously investigated. We assessed the acute effect of estradiol on collateral blood flow velocity with the Flowire during percutaneous transluminal coronary angioplasty and found that intracoronary estradiol decreased collateral blood flow velocity compared with controls.

Estrogen replacement therapy and exercise performance in postmenopausal women with coronary artery disease

We treated 10 postmenopausal women with stable angina, positive exercise test, and documented coronary artery disease with oral conjugated equine estrogen (0.625 mg/day of Premarin) or placebo for 4 weeks, in random order, with crossover after a 4-week washout period. Exercise tests, performed after each treatment period while the patients were taking their usual antianginal drugs showed no differences; thus, short-term estrogen does not improve exercise-induced ischemia compared with placebo.

Decreased vasomotor effect of endothelin on the coronary arteries during angioplasty in hypertensive patients

To investigate if the response of the contralateral artery during coronary angioplasty (PTCA) is different in hypertensive than in normotensive patients and whether this response is related to plasma levels of endothelin-1 (ET-1). We examined the change in ET-1 plasma levels and the reactivity of the left circumflex artery (LCx) during PTCA of the left anterior descending branch in 10 hypertensive and 23 normotensive patients. Peripheral vein blood samples were drawn for ET-1 estimation at baseline, after the end of the first balloon inflation, at the end of PTCA, and 4 h later. Angiograms of the LCx were obtained at baseline and during the 1st balloon inflation. The ET-1 level in hypertensives increased from 6.81 +/- 3.76 at baseline to 7.54 +/- 4.76 pmol/l (P = n.s.) at the end of PTCA, while in normotensives it increased from 8.21 +/- 3.73 to 11.56 +/- 5.04 pmol/l (F = 7.48, P = 0.0002) respectively. The LCx distal segment diameter increased from 1.29 to 1.50 mm during balloon inflation in hypertensive, and from 1.44 to 1.53 mm (F = 5.03, P = 0.03) in normotensives. The diameter increase was related to the baseline ET-1 level (r = -0.67, P = 0.005) in the normotensives, but not in the hypertensives. Thus ET-1 has a weaker vasomotion effect on the coronary vasculature in hypertensives than in normotensives during PTCA.

Protection from preconditioning can be reinstated at various reperfusion intervals

The aim of this study was to evaluate the way in which short-term protection declines and is eventually lost in preconditioning and to determine the efficacy of a second preconditioning at various reperfusion intervals. Male rabbits were divided into six groups. Forty-five minutes (sustained) ischemia followed by 120 minutes reperfusion was applied 60, 65, 70, 75, and 80 minutes after a 5 minute preconditioning (groups A, B, C, D, and E) and in a control group (F) after no preconditioning. The infarct to risk ratio (I/R) was 38.3 +/- 3.5% in group A, 46.0 +/- 7.8% in B, 61.6 +/- 9.7% in C, 68.1 +/- 4.2% in D, 64.5 +/- 7.8% in E, and 61.0 +/- 7.7% in F. Group A had a smaller I/R compared with groups C, D, E, and F (p < 0.05). In another series, groups G, H, and I were exposed to two 5-minute preconditioning stimuli, separated, respectively, by 45, 60, and 75 minutes of reperfusion; 10 minutes after the last preconditioning, the animals were exposed to 45-minutes ischemia and 120 minutes reperfusion. Groups A and D (with the smaller and higher I/R ratio) were also incorporated into this protocol in order to compare the effect of the additional preconditioning with the single one. The I/R ratio was 25.4 +/- 8.5% in group G, 22.8 +/- 7.0% in group H, and 14.7 +/- 4.0% in group I (p = NS). Group D showed a higher I/R compared with groups G, A, and H (p < 0.01), and group I had a smaller I/R compared with groups A (p < 0.01) and D (p < 0.001). Cardioprotection after a first preconditioning declines gradually and is eventually lost. An additional preconditioning is always effective, and the longer the interval from the first preconditioning, the more potent is the effect.

Alterations in circulating cyclic guanosine monophosphate (c-GMP) during short and long ischemia in preconditioning

The aim of this study was to investigate if levels of circulating cyclic guanosine monophosphate (c-GMP) alter in preconditioning. Twenty-eight rabbits were divided into four groups. In vivo hearts were preconditioned, either with 5 min (group A, n = 8) or with 1 min (group B, n = 8) ischemia, followed by 10 min reperfusion, while groups C (n = 7) and D (n = 5) had no interventions. Protection was determined by subjecting groups A, B and C (but not D) to 30 min regional ischemia which was followed (including group D) by 2 h reperfusion. Seven blood samples were collected for the assessment of circulating c-GMP at different points of time. All results were expressed in pmol/ml using radio-immunoassay and the infarcted to risk area in percent using fluorescent particles and tetrazolium chloride (TTC). Circulating c-GMP increased during long ischemia only in group A (baseline value 47 +/- 4, long ischemic values 60.5 +/- 4 and 60.4 +/- 4, p < 0.05). Circulating c-GMP in group A was significantly higher in the middle of the long ischemia in comparison to the groups B, C and D (60.5 +/- 4 vs 43.9 +/- 4, 45.8 +/- 5 and 43.6 +/- 4, p < 0.05). Infarcted to risk ratio was lower in group A than in groups B and C (12.2 +/- 4 vs 29.6 +/- 6 and 34.2 +/- 6 respectively, p < 0.05). Circulating c-GMP is increased in classically preconditioned in comparison to ineffectively preconditioned hearts or to control groups. This elevation may be related to the protective effect of this phenomenon.

Intracoronary cyclic-GMP and cyclic-AMP during percutaneous transluminal coronary angioplasty

We investigated intracoronary cyclic-guanosine monophosphate (c-GMP) levels during percutaneous transluminal coronary angioplasty (PTCA) since experimental studies have shown the endothelial origin of c-GMP production. Intracoronary c-GMP and cyclic adenosine monophosphate (c-AMP) were measured during coronary angioplasty in 24 patients with chronic coronary artery disease. Four coronary blood samples were taken through a catheter from the coronary artery the first sample before coronary angiography and the other three from distal to coronary obstruction, as follows: before the balloon inflation, at the maximum inflation and 5 min after restoration of coronary flow. c-GMP increased from 7.9 +/- 1.0 pmol/ml and 7.5 +/- 0.9 pmol/ml before angiography and balloon inflation to 11.1 +/- 1.3 pmol/ml at the maximum inflation (P < 0.01), with a trend to decrease 5 min after the end of the intervention (9.5 +/- 1.0 pmol/ml, P: NS). Intracoronary c-AMP levels remained almost unchanged. Five venous samples were taken to measure c-AMP before coronary angiography, before PTCA, and 5 min, 2 h and 24 h after PTCA. c-AMP values 2 and 24 h after PTCA (17.8 +/- 1.7 pmol/ml and 17.5 +/- 1.7 pmol/ml, respectively) were lower than the highest value (22.1 +/- 2.1 pmol/ml) found 5 min after PTCA, (P < 0.001). c-GMP increases distal to coronary obstructive lesion during PTCA at the time of balloon inflation, while c-AMP remains unchanged. c-AMP rises in venous circulation only. PTCA stimulates the mechanism of c-GMP release, while systemic c-AMP increase seems to be related to the stress occurring during catheterisation and PTCA.

Effects of atrial, ventricular, and atrioventricular sequential pacing on coronary flow reserve

Experimental animal data have indicated that altered left ventricular depolarization sequence as a result of right ventricular pacing may diminish coronary blood flow in the distribution of the left anterior descending coronary artery. To further investigate this, we compared the effects of atrial, ventricular, and atrioventricular (AV) sequential pacing on coronary flow reserve. Twenty-seven patients (24 male, mean age 55 +/- 7 years) with normal left anterior descending coronary arteries were studied. Coronary flow reserve was calculated as the ratio of mean flow velocity at maximal coronary vasodilatation to mean flow velocity at baseline. The study consisted of two parts. In the first part, AV sequential pacing was compared to atrial pacing at the same rate; coronary flow reserve did not differ significantly between the two pacing modes (14 patients, 4.85 +/- 1.88 vs 5.47 +/- 1.55, respectively, P > 0.05). In the second part, all three pacing modalities were compared; coronary flow reserve was significantly higher during ventricular compared to AV sequential pacing, but not significantly different compared to atrial pacing (3.69 +/- 1.42 vs 2.90 +/- 0.86 vs 3.11 +/- 0.89, respectively, P < 0.05). This difference was secondary to a significant decrease in mean baseline velocity during ventricular pacing, while mean velocity during hyperemia was comparable between the three pacing modes. It is concluded that AV sequential pacing does not appear to exert a significant effect on coronary flow reserve. Ventricular pacing, however, may lower resting coronary blood velocity in some patients, without affecting maximal coronary blood velocity, resulting in a higher coronary flow reserve.

Diastolic aortic pressure rise during percutaneous transluminal coronary angioplasty: an index of left ventricular systolic dysfunction

OBJECTIVES

To investigate the relation between diastolic aortic pressure response and left ventricular systolic dysfunction during percutaneous transluminal coronary angioplasty.

BACKGROUND

The abnormal diastolic blood pressure rise during exercise in patients with coronary artery disease probably reflects left ventricular systolic dysfunction rather than the number of stenosed coronary arteries.

METHODS

Aortic blood pressures and left ventricular systolic function indices were estimated in 26 patients with single proximal stenosis of the left anterior descending coronary artery both before and during angioplasty.

RESULTS

During coronary angioplasty all patients presented an increase in diastolic aortic pressure (P << 0.001), 8-12s before intracoronary electrocardiographic changes. During acute ischaemia there was a decrease in left ventricular ejection fraction (P << 0.001) and stroke volume (P << 0.001) and an increase in end systolic volume (P << 0.001) and left ventricular end diastolic pressure (P << 0.001). No statistically significant changes were observed in systolic blood pressure or heart rate. The aortic diastolic pressure increase was correlated with the decrease in ejection fraction (r = -0.95, P << 0.001) and with the increases in end systolic volume (r = 0.86, P << 0.001) and left ventricular end diastolic pressure (r = 0.85, P << 0.001).

CONCLUSIONS

The rise in diastolic aortic pressure during percutaneous transluminal coronary angioplasty occurs earlier than intracoronary electrocardiographic changes and is related to ischaemic left ventricular systolic dysfunction.

Vein plasma endothelin-1 and cyclic GMP increase during coronary angioplasty is related to myocardial ischaemia

Endothelin-1 and cyclic guanosine monophosphate (c-GMP) peripheral vein plasma levels increase during coronary angioplasty, but the reason for this increase has not been elucidated. The purpose of this study was to investigate whether these changes are related to myocardial ischaemia, or to mechanical artery injury induced during the procedure. Thirty-two patients with stable angina pectoris and a single lesion were studied. They were aged 56 +/- 8 and were undergoing balloon angioplasty. Eight arteries were totally occluded and 24 were partially occluded. Blood samples were drawn from a peripheral vein after coronary artery engagement with the guiding catheter (baseline), after the first balloon inflation, immediately after the end of the procedure, and 4 h later. In the total occlusion group endothelin-1 increased by 7% (P ns), whereas in the partial occlusion group it increased by 45% after the procedure (P < 0.001). c-GMP in the partial occlusion group increased by 41% (P < 0.001) after the procedure whereas in the total occlusion group it increased by 5% (P ns). Thus, the increase in endothelin-1 and c-GMP peripheral vein plasma levels after coronary angioplasty is related to myocardial ischaemia rather than to mechanical artery injury.

The reactivity of the contralateral artery at the time of balloon dilation during coronary angioplasty

The response of the contralateral arteries was investigated during balloon angioplasty of the left anterior descending artery. Thirty patients were studied. Coronary arteriograms were obtained at baseline, during maximal balloon inflation and at the end of the procedure. Luminal diameter was measured by a quantitative coronary arteriography analysis system. During balloon inflation the luminal diameter of the proximal segment of the right coronary artery increased by 2.4 +/- 6% (P < 0.05), and that of the left circumflex artery increased by 0.6 +/- 6% (P = ns). Both returned to near baseline values after angioplasty. In patients with increased collaterals during balloon inflation the left circumflex proximal segment increased more significantly than in patients with unchanged collaterals. The luminal diameter of the distal segment of the right coronary artery increased by 9 +/- 8% (P < 0.001) and that of the left circumflex artery by 8 +/- 11% (P < 0.01) during balloon inflation, returning to near baseline values after angioplasty. Thus, vasodilation of the contralateral arteries during balloon inflation at the time of coronary angioplasty occurs mainly in the distal segments, and appears to be related to an increase in collateral filling.

Systolic functional response of normal older and younger adult left ventricles to beta-blockade during exercise

There is controversy over the effects of beta-blockade on the left ventricular systolic response of the heart of the elderly to stress. In this study we compared the effects of acute beta-blockade in normal older and younger adult left ventricles during exercise. The study population consisted of 17 healthy elderly people, 67 +/- 3 years old, while 18 young normal subjects, 31 +/- 4 years old, served as controls. A symptom-limited exercise treadmill test was performed before and 15 minutes after intravenous administration of 0.12 mg propranolol/kg. M-mode echocardiographic studies were performed before and immediately after each test. Intravenous propranolol at rest decreased heart rate by 14 +/- 7 beats/min in the elderly and by 7.5 +/- 8 beats/min in the young (p = 0.02), decreased the double product by 2500 +/- 1200 mmHg/min and 1830 +/- 970 mmHg/min (p = 0.05), respectively; changed the left ventricular end-systolic dimension by +0.21 +/- 0.36 cm and +0.03 +/- 0.24 cm (p = 0.09), respectively; and changed the end-diastolic dimension by +0.22 +/- 0.46 cm in the elderly and by -0.02 +/- 0.32 cm in the young (p = 0.08). The change in fractional shortening was -1.22 +/- 4.17% in the elderly and -0.78 +/- 4.05% in the young (p > 0.05), and the decrease in the systolic blood pressure/end-systolic dimension ratio was 5.9 +/- 7 mmHg/cm and 4.3 +/- 3.8 mmHg/cm, respectively (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)