[Difficult diagnosis of coronary insufficiency].
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Coronary Disease↗
Biomedical subjects
R Nordlander
Publications and source records attributed to R Nordlander.
Coronary venous retroinfusion of felodipine reducing infarct size without affecting regional myocardial blood flow.
Effects on the ischaemic and reperfused myocardium of felodipine, a vasoselective calcium blocker, retrogradely infused into the coronary vein was investigated in a porcine model. Sixteen open-chest pigs underwent 45 min of myocardial ischaemia by occlusion of the left anterior descending coronary artery followed by 4 h of reperfusion. Either felodipine (felo-retro group, 7 nmol.kg-1: n = 6) or the corresponding amount of vehicle (vehicle group: n = 5) was retroinfused over 30 min starting 5 min prior to reperfusion. In a third group, the same amount of felodipine was administered intravenously (felo-i.v. group n = 5). Myocardial regional blood flow was measured with radioactive microspheres prior to ischaemia and at different times of reperfusion. Infarction size, expressed as a percentage of the area at risk, was significantly reduced to 62 +/- 12% in the felo-retro group as compared to 86 +/- 12% (P < 0.05) and 94 +/- 5% (P < 0.05) in the vehicle and felo-i.v. group, respectively. Following an early hyperaemia, the regional blood flow decreased uniformly in the reperfused myocardium in all three groups and there were no significant differences between the groups at any period of reperfusion. In conclusion, felodipine retroinfused into the coronary vein could salvage ischaemic and reperfused myocardium without affecting the regional blood flow. The mechanism of this protective effect should be explained by factors other than an increased myocardial blood flow during reperfusion.
Animals↗
Choosing the stimulation rate in patients with intermittent bradycardia and a single lead pacemaker.
In order to assess the prevalence of intermittent bradycardia in a pacemaker population, we retrospectively evaluated the occurrence of intrinsic heart activity in 229 patients with ventricular pacing. Spontaneous heart activity was recorded in 60% of the patients. However, the stimulation rate had been decreased in only 40% of the patients in order to allow for longer periods of intrinsic heart activity. In the second part of the study we prospectively assessed differences in pacemaker utilization in 19 patients with intermittent bradycardia and single lead pacemakers. All patients were observed over four periods of 14 days, with the following pacing modes: 70 beats/min, 50 beats/min, hysteresis sensing 50 beats/min, and pacing 70 beats/min; and search hysteresis sensing 50 beats/min and pacing 70 beats/min. Search hysteresis pacing is a new feature that theoretically allows for a shorter time of pacing than that of hysteresis pacing. A reduction in the stimulation rate from 70 beats/min to 50 beats/min resulted in a 60% reduction in pacemaker utilization (P < 0.05). Search hysteresis decreased pacemaker utilization by 33% (P < 0.05). There was no statistical difference between conventional hysteresis and fixed rate pacing at 70 beats/min. Most patients found fixed rate pacing preferable to hysteresis pacing. In order to minimize battery consumption and to avoid unfavorable hemodynamics in patients with ventricular pacing, the stimulation mode and rate should be optimized in patients with intermittent bradycardia to allow for longer periods of intrinsic heart activity.
Aged↗
Short-term synchronized retroperfusion before reperfusion reduces infarct size after prolonged ischemia in dogs.
BACKGROUND: Previous studies have demonstrated that synchronized coronary venous retroperfusion (SRP) can restore blood flow to the ischemic myocardium, resulting in infarct size reduction and improvement of the left ventricular function. Despite the nutritive blood flow achieved by SRP being relatively limited, SRP has been shown to improve washout of by-products from the ischemic myocardium. The aim of this study was to investigate whether short-term SRP immediately prior to reperfusion would attenuate the deteriorative phenomena following reperfusion. METHODS AND RESULTS: Closed-chest anesthetized dogs underwent 3 hours of left anterior descending coronary artery (LAD) occlusion. The dogs were then randomized into two groups: (1) control group (n = 9), in which the occlusion was immediately followed by 3-hour reperfusion; or (2) SRP group (n = 9), in which SRP was started 3 hours after occlusion and maintained for 30 minutes with sustained occlusion followed by 2.5-hour reperfusion with simultaneous discontinuation of SRP. There were no statistical differences between the groups in global hemodynamics and degree of ischemia measured by radiolabeled microspheres. Myocardial infarct size (triphenyltetrazolium method) expressed as percentage of risk area was significantly smaller in the SRP group (24 +/- 7%, mean +/- SEM) than in the control group (54 +/- 9%). The extent of myocardial hemorrhage expressed as percentage of infarct size was also significantly reduced in the SRP group (3 +/- 2%) compared with the control group (24 +/- 6%). The increase in end-diastolic wall thickness in the ischemic area after reperfusion assessed by two-dimensional echocardiography was significantly less in the SRP group. Blood flow measurements after reperfusion demonstrated the occurrence of no-reflow phenomenon only in the control group. Histological examination revealed extensive myocardial hemorrhages only in the control group, which extended into the nonnecrotic myocardium in four of nine hearts and extensive contraction band necrosis compared with the SRP group. CONCLUSIONS: Short-term SRP prior to reperfusion can reduce infarct size, myocardial hemorrhage, wall swelling, and no-reflow phenomenon. The mechanism of this beneficial effect is not clear but might be due to gradual reperfusion and washout of by-products from the ischemic myocardium before fully oxygenated arterial blood reperfusion.
Animals↗
[Thrombolytic treatment in wrongly diagnosed myocardial infarction].
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Adult↗
[2 years of the Swedish pacemaker registry: a certain centralization of activities can be appropriate].
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Cardiology↗
Quality-of-life in patients treated with atrioventricular synchronous pacing compared to rate modulated ventricular pacing: a long-term, double-blind, crossover study.
To investigate whether the preservation of atrioventricular (AV) synchronization matters for quality-of-life during pacemaker treatment we assessed 17 consecutive patients with high degree AV block and preserved sinus node function in a double-blind, long-term crossover study. A questionnaire with regard to cardiovascular symptoms, sleep disturbances, cognitive functioning, physical ability, social interaction, emotional functioning, and self-perceived health was completed after 2 months of atrial synchronous (DDD) and rate modulated ventricular pacing (VVI,R), respectively. A significant improvement in shortness of breath, dizziness and palpitations as well as an improvement of cognitive functioning was observed during DDD pacing. Nine patients preferred the DDD mode and three the VVI,R mode. The remaining five patients did not express any preference. The preference for the DDD mode was explained by a significant reduction of cardiovascular symptoms and an improved self-perceived health, physical ability, and psychological well-being during DDD pacing. All differences in quality-of-life parameters between the two modes of pacing favored the DDD mode and no adverse effects of this mode were found. Thus, the maintenance of AV synchrony adds further symptomatic relief compared to rate increase alone. The results indicate that DDD pacing is the preferred mode of pacing in patients with high degree AV block and preserved sinus node function.
Cardiac Pacing, Artificial↗
The hemodynamic importance of atrial systole: a function of the kinetic energy of blood flow?
The relative importance of atrial systole on left ventricular filling was investigated at rest and during exercise in 25 patients with dual chamber pacemakers. The mean blood flow velocity over the mitral valve, the velocities of the rapid filling phase (E), the active filling phase (A), and the E/A ratio were determined by pulsed Doppler-echocardiography. The patients were first examined at rest during AV sequential pacing (DVI) at 70 and 104 beats/min. The investigation was subsequently repeated during atrial synchronous pacing (VDD) at rest and during supine submaximal exercise at workloads adjusted to achieve heart rates corresponding to those during DVI pacing. The mean blood flow velocity at rest did not differ between DVI and VDD pacing at 70 beats/min (0.46 vs 0.49 m/sec). When the resting heart rate was increased to 104 beats/min (DVI) the mean blood flow velocity increased to 0.56 msec (P < 0.001). At a corresponding heart rate during exercise (VDD) the velocity increased to 0.70 msec (P < 0.001). At a resting heart rate of 70 beats/min the E/A ratio (n = 14) did not differ significantly between DVI and VDD pacing. With an increased resting heart rate (DVI) the E/A ratio decreased from 0.94 +/- 0.45 to 0.78 +/- 0.18; NS. When the heart rate increased during exercise (VDD) the E/A ratio increased from 0.75 +/- 0.14 to 0.97 +/- 0.16; P < 0.001. There was a positive correlation between the increase of the mean blood flow velocity and the increase of the E/A ratio during exercise (r = 0.69, P < 0.01). No such correlation was found when the heart rate was changed at rest. Thus, the importance of atrial systole on ventricular filling diminishes during exercise in accordance with increasing blood flow velocity, which by physical principles is related to the kinetic energy. The relative importance of atrial systole is hence inversely correlated to the kinetic energy of the blood flow.
Aged↗
A double-blind study of submaximal exercise tolerance and variation in paced rate in atrial synchronous compared to activity sensor modulated ventricular pacing.
To assess the variation in paced rate during everyday activity and the importance of atrioventricular synchronization (AV synchrony) for submaximal exercise tolerance, atrial synchronous (DDD) and activity rate modulated ventricular (VVI,R) pacing were compared in 17 patients with high degree AV block. The patients were randomly assigned to either mode and evaluated by treadmill exercise to moderate exertion and by 24-hour Holter monitoring after 2 months in the DDD and VVI,R modes, respectively. At the end of the study, the patients were programmed to the pacing mode corresponding to the preferred study period. During the treadmill test, the mean exercise time to submaximal exertion (Borg 5/10), exertion ratings and respiratory rate did not differ between pacing modes despite a significantly lower ventricular rate in the VVI,R mode. The atrial rate during VVI,R pacing was significantly higher than the ventricular rate, but did not differ from the ventricular rate during DDD pacing. There was a diurnal variation in paced rate in both pacing modes. Paced ventricular rate was, however, higher and variation in paced rate greater in DDD compared to VVI,R pacing. Nine patients preferred the DDD mode, three patients preferred the VVI,R mode, while five subjects did not express any preference. The results from this study indicate that the variation in paced rate during activity sensor-driven VVI,R pacing does not match that during DDD pacing neither during everyday activities nor during submaximal treadmill exercise. Nevertheless, no differences in exercise time, Borg ratings, and respiratory rate during submaximal exercise were found. Thus, for most patients with high degree AV block, DDD and VVI,R pacing seem equally satisfactory for submaximal exercise.
Cardiac Pacing, Artificial↗
Is DDD pacing superior to VVI,R? A study on cardiac sympathetic nerve activity and myocardial oxygen consumption at rest and during exercise.
Rate responsive ventricular pacing (VVI,R) has been demonstrated to equal atrial synchronous ventricular pacing (DDD) with regard to hemodynamics and exercise tolerance. Whether the two modes are also comparable, with regard to cardiac metabolic effects, is not yet clear. We assessed central hemodynamics, cardiac sympathetic nerve activity (cardiac norepinephrine overflow), and myocardial oxygen consumption in 16 patients treated with rate responsive atrial synchronous ventricular pacemakers (DDD,R) due to high degree AV block. The study was performed at rest and during supine exercise at two workloads (30 +/- 12 and 68 +/- 24 watts, respectively) during VDD and rate matched VVI pacing (VVIm). Ventricular rates at rest and during both workloads were almost identical. Cardiac output at rest tended to be higher in the VDD mode, due to a slightly higher stroke volume. Central pressures including right atrial pressure and pulmonary capillary wedge pressure were similar in the pacing modes. The coronary sinus blood flow, the coronary sinus arteriovenous oxygen difference, and the myocardial oxygen consumption did not differ between the two pacing modes. Cardiac norepinephrine overflow was similar in the two pacing modes, at rest or during exercise. Thus, we found no significant differences between VDD and VVIm pacing with regard to central hemodynamics, cardiac sympathetic nerve activity (cardiac norepinephrine overflow), or myocardial oxygen consumption either at rest or during moderate exercise.
Aged↗
The high-risk unstable angina patient. An approach to treatment.
Unstable angina, an intermediate stage in acute coronary ischaemic syndromes, accounts for about 50% of all admissions to the coronary care units in the United States today. It may progress to myocardial infarction in 15% of cases in the first 2 days, and the in-hospital mortality rate is 5%. The pathological hallmark of this syndrome, confirmed by angioscopy, is fissure of the atherosclerotic plaque within the coronary artery, leading to platelet adhesion and aggregation and fibrin-platelet thrombus formation, which may accelerate progression of the stenotic lesion. Management of unstable angina is aimed at ameliorating symptoms and reducing ischaemia, improving ventricular function, preventing recurrent ischaemia, myocardial infarction and death, and lastly, containing progression of the underlying coronary artery disease. Acute management includes bedrest, aspirin, heparin, nitroglycerin (glyceryl trinitrate) infusion and beta-blockers and calcium channel blockers in selected cases. After the patient is clinically stabilised, provocative tests and angiography may be performed, to be followed by angioplasty or bypass surgery, if necessary. In cases that are refractory to optimal medical therapy, interventions should be performed on a more emergent basis. Long term management includes aspirin and beta-blockers, if there is prior infarction, and control of the conventional risk factors.
Angina, Unstable↗
Clinical experience of pacemaker treatment in children.
Pacemaker treatment is more complicated in children than in adults, mainly because of electrode problems. A pacemaker system was implanted in 23 children aged 2 days-14 years (mean 4.8 years, with 11 less than or equal to 3 years) at the Karolinska Hospital since 1983. The indications for pacing were peroperative atrioventricular block (AVB) in 13 cases, congenital AVB in five, sinoatrial disorder in four and slow ventricular arrhythmia in one case. The initially implanted electrode was epicardial in ten children (in the first 2 years of the study) and endocardial in the other 13. Eight of the ten epicardial electrodes had to be replaced by endocardial within a mean of 2.5 years. There were 18 reoperations, the reasons being increased threshold/exit block--all epicardial leads (8 cases), electrode failure (1), 'stretching' of the electrode secondary to body growth (4), local infection (3) and generator replacement (2). The reoperation rate was unacceptably high in children with epicardial electrodes. Endocardial pacing is the method of choice even for small infants.
Adolescent↗
Survival in patients with permanent pacemakers.
Atrioventricular block I has a benign natural course, and permanent pacing is not warranted. Second-degree AV block, including both type I and type II, can have an ominous course, especially in older patients with underlying heart disease. One study claims that the prognosis in patients with second-degree AV block, irrespective of type, is improved by permanent pacing. In spite of lack of controlled studies it has been convincingly shown that VVI pacing prolongs life in patients with high-grade AV block. Two studies suggest that atrial synchronous pacing in patients with congestive heart failure and high-grade AV block might improve their survival. Studies comparing survival with different pacing modes in patients with sinus node disease support the hypothesis that physiologic pacing can improve survival. Prophylactic pacemaker implantation even in symptomatic patients with chronic bifascicular block does not seem to protect them from sudden death.
Cause of Death↗
Coronary veins: an alternate route to ischemic myocardium.
Acute myocardial ischemia is the primary cause of concern during myocardial infarction and unstable angina, and the cornerstone of modern therapy is rapid establishment of antegrade blood flow. The ultimate success of reperfusion depends on the duration and severity of ischemia before revascularization. Even brief ischemia occurring during angioplasty may cause reversible myocardial dysfunction. Several interventions are available to minimize the negative effects of acute myocardial ischemia. Synchronized coronary venous retroperfusion is a myocardial support technique in which autologous arterial blood is shunted from the femoral artery into the ischemic myocardium via the coronary sinus. Retroperfusion has been studied clinically during angioplasty and has been shown to ameliorate and delay the onset of ischemia. It has also been beneficial during abrupt closure of the coronary artery after angioplasty as a bridge to definitive therapy. Preliminary reports have indicated the efficacy of retroperfusion in medically refractory unstable angina. Because of its retrograde approach, this technique may serve as an alternate route to an otherwise inaccessible, ischemic myocardium for delivery of blood and other cardioprotective agents.
Angioplasty, Balloon, Coronary↗
[The Swedish pacemaker registry is a source of patient safety].
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Humans↗
Exercise performance and beta-adrenergic blockade in patients with complete heart block treated with ventricular inhibited pacing.
The effect of beta-adrenergic blockade (propranolol) on exercise performance was studied in 15 patients (12 men and 3 women, mean age 70 years) with complete heart block treated with a ventricular-inhibited pacemaker (VVI). In a double-blind procedure, the patients were randomly given either 0.1 mg/kg of propranolol or saline solution i.v. before a first exercise test and vice versa before a second test. The interval between the tests was 24 hours. Nine patients were in sinus rhythm, 4 patients had atrial flutter, and 2 others had atrial fibrillation. The exercise capacity was on an average 11% lower with propranolol than with placebo (p less than 0.001). The most marked reductions (20 and 33%) were found in the two patients with atrial fibrillation. The atrial rate in patients with sinus rhythm was significantly lower with propranolol than placebo both at rest (68 vs. 83 beats/min, p less than 0.001) and at maximal work load (91 vs. 141 beats/min, p less than 0.001). The present findings show that beta blockade has negative effects on exercise capacity in patients with complete heart block treated with VVI pacemakers. This finding should be considered in the selection of drug treatment in patients with fixed rate pacing and concomitant hypertension and/or ischemic heart disease.
Aged↗
Preservation of regional myocardial ultrasonic backscatter and systolic function during brief periods of ischemia by synchronized coronary venous retroperfusion.
This study examines the effects of brief periods of ischemia on average and cardiac cycle-dependent variation of regional ultrasonic backscatter paralleled with changes in regional myocardial contraction, and to what extent these changes could be reversed by synchronized coronary venous retroperfusion. In five closed-chest dogs, the left anterior descending coronary artery was occluded on four occasions for a 2-minute period and retroperfusion was applied randomly to two of the coronary occlusions. Complete functional recovery was allowed between the occlusions. Two-dimensional echocardiographic images were obtained before and at the peak of the 2-minute occlusion period. Regional myocardial contraction as measured by fractional area change and systolic wall thickening during untreated occlusions decreased from 33.9 +/- 14.0% to -0.15 +/- 6.2%, and from 22.0 +/- 1.8% to -17.9 +/- 2.2%, whereas during retroperfusion-treated occlusions it changed from 37.4 +/- 8.5% to only 23.4 +/- 11.2% (p less than 0.005 versus baseline), and from 24.1 +/- 2.8% to only 12.7 +/- 2.0% (p less than 0.005 versus baseline), corresponding to a preservation of 62% and 52% of baseline regional contraction, respectively. Average regional gray level (arbitrary units) during untreated coronary occlusions exhibited a significant increase in the ischemic regions, from 5.6 +/- 2.7 at baseline to 11.5 +/- 4.4 during occlusion (p less than 0.005); during retroperfusion-treated occlusions, average gray level increased from 4.7 +/- 3.6 to only 6.3 +/- 3.6 (NS). Untreated coronary artery occlusions resulted in a systolic increase in gray level in the ischemic region, followed by a diastolic decrease.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Coronary venous retroinfusion of deferoxamine reduces infarct size in pigs.
The efficacy of coronary venous retroinfusion of the iron chelator deferoxamine was studied in 24 pentobarbital-anesthetized open chest pigs with a 60 min occlusion of the left anterior descending coronary artery followed by 3 h of reperfusion. Eight retrogradely treated pigs were given 10 mg/kg body weight of deferoxamine by way of the anterior interventricular vein and eight systemically treated pigs received the same doses of deferoxamine intravenously. Drug infusions lasted for 5 min, beginning 15 min before reperfusion. Eight control pigs received systemic intravenous saline solution. Myocardial area at risk and necrotic area were assessed by the monastral blue dye and the triphenyltetrazolium chloride staining method, respectively. There were no significant differences in hemodynamics or regional myocardial function (sonomicrometry) among the groups. Infarct size expressed as percent of risk area was 73.9 +/- 13.5% in the control group, 70.6 +/- 16.4% in the systemically treated group and 48.5 +/- 21.4% (p less than 0.05) in the retrogradely treated group. In conclusion, deferoxamine significantly reduced infarct size after coronary occlusion only when given regionally by way of the coronary vein. Because there was no significant hemodynamic effect caused by deferoxamine infusion, it is suggested that this drug prevents postischemic reperfusion injury by a direct cardioprotective effect.
Animals↗