The cold pressor test: Vascular and myocardial response patterns and their stability

The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response panerns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval.     

Recanalization of Chronically Occluded Coronary Arteries: Single-Center Experience in 400 Cases, Including Long-Term Angiographic Follow-Up

The study presented comprises the initial and angiographic long-term results of a consecutive series of recanaliza-tion procedures in a single center. Between 1988 and 1992, a total of 400 patients underwent transluminal recanalization for total coronary occlusions. In 82% of successfully attempted patients, the occlusion could be passed by a standard guidewire. The overall initial success rate was 75% (298 of 400). The highest success rates could be achieved in the left circumflex artery (84%) and left anterior descending coronary artery (77%). Complications were uncomplicated myocardial infarction in ten patients (2.5%) and death in two patients (0.5%). Angiographic follow-up 3–6 months after recanalization could be achieved in 263 (88%) of 298 patients. Significant restenosis (≥ 50% minimum lumen diameter) was found in 57 (22%) of 263, and reocclusion was present in 38 (14%) of 263 patients, resulting in a total recurrence rate of 36%. In conclusion, recanalization can be performed with an initial success rate of 75% using bare-wire technique under the prerequisite operator experience. If a nearly complete angiographic follow-up is performed, the overall recurrence rate is 36%, which seems to be very acceptable in comparison with PTC A results for incomplete obstructions published so far . (J Interven Cardiol 1996;9:73–79)     

Bleeding after thrombolysis in acute myocardial infarction

232 consecutive patients with acute myocardial infarction weretreated either with 2 x 10⁶ IU urokinase as an intravenous bolusinjection, or 250000 IU streptokinase intracoronary, or 60 mgrecombinant tissue-type plasminogen activator (rt-PA) over 90min. All patients enrolled had chest pain for more than 30 minand less than 3 h before admission and a typical electrocardiogram.Contra-indications to thrombolytic treatment were absent. Allbleeding complications occurring within 24 h after admissionwere assumed to be due to thrombolytic therapy. Bleeding complicationsoccurred in 14 patients (6.5%). Only seven patients receiveda blood transfusion (3%). No correlation was evident betweenprevious hypertension, diabetes mellitus, smoking, sex, age,fibrinogen level before and 24 h after thrombolytic therapyand bleeding complications. The risk of bleeding was not significantlydifferent between the different thrombolytic regimens despitemarked differences in the fall of the fibrinogen level. Thedecrease of fibrinogen following thrombolytic therapy did notinfluence the patency rate of the infarct vessel. Thrombolytictherapy in acute myocardial infarction is a safe treatment evenamong patients advanced in years and with medically controlledhypertension and diabetes mellitus, irrespective of the kindof thrombolytic treatment.     

Assessment of myocardial necrosis immediately after intracoronary thrombolysis by intracoronary injection of technetium-99m pyrophosphate

To assess myocardial necrosis immediately after intracoronarythrombolysis, thallium-201 (TL-201) and technetium-99m pyrophosphate(Tc-99m PYP) were injected simultaneously into the coronaryartery in 25 patients with acute transmural myocardial infarction.In 17 of the 25 patients, the occluded coronary artery was reopened.Minutes after the intracoronary injection of Tc-99m PYP intothe reopened coronary artery a localized accumulation was seenwithin the area of the Tl-201 defect in all patients. Controlintravenous scintigraphy, which was performed in 8 of these17 patients 1–6 days later, and in 2 patients 18 and 42days after infarction, revealed a Tc- 99m PYP spot similar tothat of the acute intracoronary Tc-99m PYP scintigram in all10 patients. In the 8 of the 25 patients, in whom intracoronary thrombolysisfailed, no localized Tc-99m PYP accumulation was seen afterinjection into the infarct vessel. In 5 of these patients, acontrol intravenous scintigram, performed 1–8 days later,resulted in a Tc-99m PYP spot in the area of the Tl-201 defect. We conclude that, in the presence of therapeutic or spontaneousreperfusion, Tc-99m PYP scintigraphy may provide a useful methodof assessing myocardial necrosis during the early stage of anacute myocardial infarction.     

Engraftment of T-Depleted Major Histocompatibility Complex-Mismatched Bone Marrow in T-Deficient versus Natural Killer-Deficient Recipients

When bone marrow transplantation recipients undergo standard pre-transplant immunosuppressive therapy, engraftment failures are significantly more frequent with the use of T-depleted allogeneic donor bone marrow cells than with T cell-containing allogeneic donor bone marrow cells. The relative importance of T versus natural killer (NK) cells in the rejection process of T-depleted donor bone marrow cells remains debatable. Here, NK- and T-deficient mouse mutants were transplanted across the same major histocompatibility complex (MHC) differences with homozygous or heterozygous T-depleted bone marrow cells. Results show that under the experimental conditions described, residual host NK cells are almost exclusively responsible for the increased rejection rate.     

Impedance of Pacemaker Leads: Correlation of Different Methods

This study compares three different pacing system analyzers, which measure impedance at different points during an impulse, with measurements telemetered from implanted pacemakers from four different manufacturers. Measurements were obtained at the time of implantation in a group of 103 patients. The measurements obtained by these different methods differ significantly from each other; the later during the impulse the impedance is measured, the higher in general its value. Interpretation of impedance values should take into account the technique of measurement.