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Interrelationships between blood pressure and contractile state in acute uremia
ABSTRACTS
INTERRELATIONSHIPS BETWEEN BLOOD PRESSURE ANU CONTRACTILE STATE IN ACUTE UREMIA Thasana Nivatpumin, MD; Tada Yipintsoi, MD, PhD; Somsong Penpsrgkul. ti, PhD; James Scheuer, MD, FACC, Montefiore Hospital and Medical Center. Bronx, N. Y.
THE DIAGNOSIS AND SURGICAL TRFA'lME!K OF COR TRIATRIATUM Jorge Oglietti, M. D., Luigi Chiariello, M. D., George J. Reul, Jr., M. D., F.A.C.C., Denton A. Cooley, M. D., F.A.C.C., Grady L. Hallman, M.D.,F.A.C.C., Texas Heart Institute, Houston, Texas
Blood pressure (Bp) and left ventricular contractility are increased in rats 24 hours after bilateral nephrectomy. To investigate the role systemic hypertension plays in the increased contractile state, the left ventricle was studied in open chest rats during both ejection (E) and isovolumic contractions (ISO) 24 hours after sham surgery (S) or bilateral nephrectomy (U)(BUN 130). Left ventricular systolic pressure (LVP) and max dP/dt were higher in U than in S during both E and ISO. The differences between U and S were not diminished by IV propranolol. When the Bp course was kept normal in U throughout the 24 hours with IP phenoxybenzamine, dP/dt was 47% higher during E and 57% higher during IS0 in U than in S. When S were treated 24 hours with SC methoxamine to equal the Bp course of U, indices of contractility increased toward those of U. but the rise in dP/dt from E to IS0 in U was twice as high as in S. With milder U (S/6 nephrectomy) studied at 48 hours (BUN 48), there was no hypertension but LVP and dP/dt during IS0 were 24 and 29% greater than S. All differences are ~(0.05. In all conditions studied EDP was the same or lower in U hearts than in paired S, but max dP/dt/max P was higher in U than S. These data indicate that although early hypertension can be associated with augmented cont.ractility, the increase in intrinsic contractility seen early in the uremic state can be dissociated from hypertension and from B-adrcnergic influences. Therefore, acute uremia per se appears to cause increased contractility.
Of the cardiac defects causing obstruction of the pulmonary venous return, car triatriatum is one of the more unusual. From 1961 through 1974, 11 patients (pts.) were The age ranged from treated for this congenital anomaly. 7 months to 36 years with two pts. under the age of one year and eight pts. under the age of six years. There were eight females and three males. Presenting symptoms were congestive heart failure and frequent respiratory infections. Chest X-ray showed cardiomegaly and increased vascular markings in all pts. The electrocardiogram demonstrated right atria1 and ventricular hypertrophy. Cardiac catheterization was done on all patients and preoperative diagnosis was obtained in only seven of the 11 In five pts. the diaphragm dividing the left atrium pts. into two chambers was seen angiographically and in three pts. a gradient across the diaphragm was demonstrated. All pts. had pulmonary arterial hypertension. Associated anomalies were present in eight of the 11 pts. Four had associated atria1 septal defects and two endocardial cushion defects. Associated anomalies were repaired at the same time of excision of the car triatriatum membrane. Operation consisted of either right or left atriotomy and total excision of the membrane. There was one operative death which occurred six days following surgery. All pts. have shown vast improvement following surgery and there have been no late deaths. Early and late results were related to the amount of pulmonary vascular resistance present preoperatively. With present techniques, car triatriatum can be easily diagnosed and results from surgical correction are gratifying.
CARDIOVASCULAR EFFECTS OF THE NEW ANTIAFRHYTHMIC AGENT, VRRAPAMIL Kanji Obayashi MDi Koichi Nagasawa MD; William J. Mandel MD, FACC; John K. Vyden MB; Department of Cardiology, Cedars-Sinai Med. Ctr. Los Angeles, CA.
EFFECTS OF SUB-THERAPEUTIC TOTHWAPBUXC DOSES OF PROCAINE AMIDE ON THB BLBCTROPBYSIOLoGICAL PROPERTIES OP THB ATRIOVBWTRICUIARCCNDlRXINGSYSTEM INMAN J. Bimbola Ogunkelu, M); Anthony N. Damato, MD; l4asood Akhtar, MD; William P. Batsford, MD; Antonio R. Caracta, MD; Sun H. Lau, MD, Cardiopulmonary Laboratory, USPHS Hospital, Staten Island, New York
Verapamil (VI, an antianginal agent with potent clinical antiarrhythmic effects, was studied to investigate its cardiovascular properties. Microelectrode studies were performed in Purkinje fiber (PF) utilizing standard techniques. Resting potential amplitude, APD, and dV/dt were significantly depressed after exposure to > 1 x lo-6 M; effects on EFfPwere minimal. Conduction velocity in linear PF was depressed but only at 2 1 x 10e5M. A marked negative chronotropic effect was noted in isolated sinus node with sinus arrest at L 1 x lo-5M. However, depression of PF automaticity was seen only at 1 x 10m4M, suggesting V has more effect on the slow inward sodium current. This is supported by V's lack of effect on membrane responsiveness until exposure to 1 x lo-4M. AV conduction studies performed in conscious dogs caused no significant changes in AH, HV, QRS intervals or heart rate at doses of 0.05, 0.1 and 0.2 mg/Kg IV; at a dose of 0.4 mg/Kg marked sinus suppression ensued. In dogs with chronic AV block, V caused an increase in ventricular automaticity. In anesthetized dogs, a dose of 0.05 mg/Kg resulted in a decrease in coronary flow (29.3 to 22.3 ml/min) possibly resulting from a decrease in LV dp/dt, aortic systolic pressure and heart rate. Doses 2 0.1 mg/Kg Iv produced similar but more pronounced changes interpreted as diminishing LV performance. In conclusion, the above studies demonstrate that V has a marked effect on sinus node function, lesser effects on PF and, in higher doses, may depress left ventricular function.
The effects of single intravenous infusions of low to telatively high doses (50 to 400 mg) of procaine amide (PA) on the functional properties of the atrioventrlcular (AV) conducting system were studied and correlated with plasma concentrations (PC) using His bundle electrograms and the atria1 extrastimulus (A2) method at constant cycle lengths (AlAl). Measurements were made within S-10 minutes after PA dosing. 50 mg of PA (5 pts) resulted in PC -3.1 s&L and produced no electraphysiological changes. 100 mg (PC 1.4 mg/L) did not change His-Purkinje system (HPS) conduction (BV interval) but increased HPS refractoriness in 3 of 5 pts. 200 mg (9 pts), 300 rag (6 pts), 400 mg (6 pts) resulted in progressive increases in PC (2.32, 3,83. 4.23 mg/L respectively) which paralleled progressive increases in WV interval (5, 8, 9 msec respectively) and refractoriness (8, 16, 26 msec respectively). In some pts the effect of 100-200 mg on HPS refractoriness was subtle and could only be detected by plotting HlH2 and VlV2 against the full range of AlA2. Increases in atria1 refractoriness were observed at doses of 300 rag or >. Doses of 100-300 mg decreased AV nodal refractoriness whereas 400 mg produced an increase. Premature ventricular beats with fixed coupling intervals were abolished with doses as low as 100 mg. The electrophysiological effects of PA correlate well with dose and plasma concentration. Ces6ation of some types of ventricular arrhythmia by sub-therapeutic doses of PA could be explained by the subtle changes in refractoriness within the HPS.
January 1975
The American Journal of CARDIOLOGY
Volume 35
161
INTERRELATIONSHIPS BETWEEN BLOOD PRESSURE ANU CONTRACTILE STATE IN ACUTE UREMIA Thasana Nivatpumin, MD; Tada Yipintsoi, MD, PhD; Somsong Penpsrgkul. ti, PhD; James Scheuer, MD, FACC, Montefiore Hospital and Medical Center. Bronx, N. Y.
THE DIAGNOSIS AND SURGICAL TRFA'lME!K OF COR TRIATRIATUM Jorge Oglietti, M. D., Luigi Chiariello, M. D., George J. Reul, Jr., M. D., F.A.C.C., Denton A. Cooley, M. D., F.A.C.C., Grady L. Hallman, M.D.,F.A.C.C., Texas Heart Institute, Houston, Texas
Blood pressure (Bp) and left ventricular contractility are increased in rats 24 hours after bilateral nephrectomy. To investigate the role systemic hypertension plays in the increased contractile state, the left ventricle was studied in open chest rats during both ejection (E) and isovolumic contractions (ISO) 24 hours after sham surgery (S) or bilateral nephrectomy (U)(BUN 130). Left ventricular systolic pressure (LVP) and max dP/dt were higher in U than in S during both E and ISO. The differences between U and S were not diminished by IV propranolol. When the Bp course was kept normal in U throughout the 24 hours with IP phenoxybenzamine, dP/dt was 47% higher during E and 57% higher during IS0 in U than in S. When S were treated 24 hours with SC methoxamine to equal the Bp course of U, indices of contractility increased toward those of U. but the rise in dP/dt from E to IS0 in U was twice as high as in S. With milder U (S/6 nephrectomy) studied at 48 hours (BUN 48), there was no hypertension but LVP and dP/dt during IS0 were 24 and 29% greater than S. All differences are ~(0.05. In all conditions studied EDP was the same or lower in U hearts than in paired S, but max dP/dt/max P was higher in U than S. These data indicate that although early hypertension can be associated with augmented cont.ractility, the increase in intrinsic contractility seen early in the uremic state can be dissociated from hypertension and from B-adrcnergic influences. Therefore, acute uremia per se appears to cause increased contractility.
Of the cardiac defects causing obstruction of the pulmonary venous return, car triatriatum is one of the more unusual. From 1961 through 1974, 11 patients (pts.) were The age ranged from treated for this congenital anomaly. 7 months to 36 years with two pts. under the age of one year and eight pts. under the age of six years. There were eight females and three males. Presenting symptoms were congestive heart failure and frequent respiratory infections. Chest X-ray showed cardiomegaly and increased vascular markings in all pts. The electrocardiogram demonstrated right atria1 and ventricular hypertrophy. Cardiac catheterization was done on all patients and preoperative diagnosis was obtained in only seven of the 11 In five pts. the diaphragm dividing the left atrium pts. into two chambers was seen angiographically and in three pts. a gradient across the diaphragm was demonstrated. All pts. had pulmonary arterial hypertension. Associated anomalies were present in eight of the 11 pts. Four had associated atria1 septal defects and two endocardial cushion defects. Associated anomalies were repaired at the same time of excision of the car triatriatum membrane. Operation consisted of either right or left atriotomy and total excision of the membrane. There was one operative death which occurred six days following surgery. All pts. have shown vast improvement following surgery and there have been no late deaths. Early and late results were related to the amount of pulmonary vascular resistance present preoperatively. With present techniques, car triatriatum can be easily diagnosed and results from surgical correction are gratifying.
CARDIOVASCULAR EFFECTS OF THE NEW ANTIAFRHYTHMIC AGENT, VRRAPAMIL Kanji Obayashi MDi Koichi Nagasawa MD; William J. Mandel MD, FACC; John K. Vyden MB; Department of Cardiology, Cedars-Sinai Med. Ctr. Los Angeles, CA.
EFFECTS OF SUB-THERAPEUTIC TOTHWAPBUXC DOSES OF PROCAINE AMIDE ON THB BLBCTROPBYSIOLoGICAL PROPERTIES OP THB ATRIOVBWTRICUIARCCNDlRXINGSYSTEM INMAN J. Bimbola Ogunkelu, M); Anthony N. Damato, MD; l4asood Akhtar, MD; William P. Batsford, MD; Antonio R. Caracta, MD; Sun H. Lau, MD, Cardiopulmonary Laboratory, USPHS Hospital, Staten Island, New York
Verapamil (VI, an antianginal agent with potent clinical antiarrhythmic effects, was studied to investigate its cardiovascular properties. Microelectrode studies were performed in Purkinje fiber (PF) utilizing standard techniques. Resting potential amplitude, APD, and dV/dt were significantly depressed after exposure to > 1 x lo-6 M; effects on EFfPwere minimal. Conduction velocity in linear PF was depressed but only at 2 1 x 10e5M. A marked negative chronotropic effect was noted in isolated sinus node with sinus arrest at L 1 x lo-5M. However, depression of PF automaticity was seen only at 1 x 10m4M, suggesting V has more effect on the slow inward sodium current. This is supported by V's lack of effect on membrane responsiveness until exposure to 1 x lo-4M. AV conduction studies performed in conscious dogs caused no significant changes in AH, HV, QRS intervals or heart rate at doses of 0.05, 0.1 and 0.2 mg/Kg IV; at a dose of 0.4 mg/Kg marked sinus suppression ensued. In dogs with chronic AV block, V caused an increase in ventricular automaticity. In anesthetized dogs, a dose of 0.05 mg/Kg resulted in a decrease in coronary flow (29.3 to 22.3 ml/min) possibly resulting from a decrease in LV dp/dt, aortic systolic pressure and heart rate. Doses 2 0.1 mg/Kg Iv produced similar but more pronounced changes interpreted as diminishing LV performance. In conclusion, the above studies demonstrate that V has a marked effect on sinus node function, lesser effects on PF and, in higher doses, may depress left ventricular function.
The effects of single intravenous infusions of low to telatively high doses (50 to 400 mg) of procaine amide (PA) on the functional properties of the atrioventrlcular (AV) conducting system were studied and correlated with plasma concentrations (PC) using His bundle electrograms and the atria1 extrastimulus (A2) method at constant cycle lengths (AlAl). Measurements were made within S-10 minutes after PA dosing. 50 mg of PA (5 pts) resulted in PC -3.1 s&L and produced no electraphysiological changes. 100 mg (PC 1.4 mg/L) did not change His-Purkinje system (HPS) conduction (BV interval) but increased HPS refractoriness in 3 of 5 pts. 200 mg (9 pts), 300 rag (6 pts), 400 mg (6 pts) resulted in progressive increases in PC (2.32, 3,83. 4.23 mg/L respectively) which paralleled progressive increases in WV interval (5, 8, 9 msec respectively) and refractoriness (8, 16, 26 msec respectively). In some pts the effect of 100-200 mg on HPS refractoriness was subtle and could only be detected by plotting HlH2 and VlV2 against the full range of AlA2. Increases in atria1 refractoriness were observed at doses of 300 rag or >. Doses of 100-300 mg decreased AV nodal refractoriness whereas 400 mg produced an increase. Premature ventricular beats with fixed coupling intervals were abolished with doses as low as 100 mg. The electrophysiological effects of PA correlate well with dose and plasma concentration. Ces6ation of some types of ventricular arrhythmia by sub-therapeutic doses of PA could be explained by the subtle changes in refractoriness within the HPS.
January 1975
The American Journal of CARDIOLOGY
Volume 35
161