bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymptomatic coronary artery disease managed by myocardial revascularization: results at 5 years.
Authors: Thurer R L , Lytle B W , Cosgrove D M , Loop F D
Published: June 2012

A consecutive series of 17 patients surgically treated for asymptomatic coronary artery disease was surveyed for survival, clinical status, and graft patency after a mean follow-up of 75 months. Documented myocardial infarction (MI), 14 transmural and 3 subendocardial, was the major indication for catheterization. All patients were asymptomatic for at least 4 months prior to surgery. Six patients had greater than 70% obstruction in one vessel, seven in two vessels, and four in three vessels. The indication for revascularization was critical stenoses in vessels supplying large areas of viable myocardium. All patients received left internal mammary artery (LIMA) grafts to the left anterior descending coronary artery; seven patients also received saphenous vein grafts (SVG) to other vessels. There was no operative or late mortality. In 12 patients, postoperative angiography (mean interval, 12 1/2 months) showed 11/12 LIMA and all SVG patent. One incompletely revascularized patient with an occluded LIMA is symptomatic. All others are fully active without symptoms or interval MI after a minimum follow-up of 5 1/2 years. The safety and long-term results of myocardial revascularization warrant its consideration for selected asymptomatic postinfarction patients.
Beneficial effects of pulsatile perfusion in the hypertrophied ventricle during ventricular fibrillation.
Authors: Bixler T J , Magee P G , Flaherty J T , Gardner T J , Gott V L
Published: June 2012

To assess the potential benefit of pulsatile perfusion inthe hypertrophied heart during fibrillation, 10 dogs with left ventricular hypertrophy, produced by previous supravalvular aortic banding, were used to compare linear and pulsatile perfusion in the fibrillating heart during total cardiopulmonary bypass. The mass spectrometer was used to measure subendocardial PCO2 and PO2 (PmCO2 and PmO2), and radioactive microspheres were utilized to measure myocardial blood flow in the same layers. Pulsatile perfusion was established using the recently develop "bubble tubing," which produces a pulse pressure of at least 20 mm Hg and can be used in a standard roller-pump apparatus. Both linear and pulsatile flows were compared at mean aortic root pressures of 80 and 50 mm Hg, and these four combinations of aortic root pressure and type of flow were employed for periods of 30 minutes each. Myocardial ischemia developed during linear coronary perfusion at 50 mm Hg, as evidenced by an elevation of PmCO2. Ischemia was not evident during pulsatile perfusion at the same mean pressure. Reversal ischemia was a result of increased myocardial blood flow and pulsatile perfusion, and this increase was shown to occur maximally in the deeper subendocardial layer. Ischemia was not eviden during linear or pulsatile perfusion at an mean perfusion pressure 80 mm Hg. Thus, if lower perfusion pressures are to be tolerated in patients with left ventricular hypertrophy, pulsatile perfusion with the bubble tubing technique may prevent the development of subendocardial ischemia or infarction.
Mild ventricular dysfunction following cold potassium cardioplegia.
Authors: Ellis R J , Gertz E W , Wisneski J , Ebert P A
Published: June 2012

The long-term effects of cold potassium cardioplegic arrest was examined in 40 patients who underwent myocardial revascularization. Comparisons between resting ejection fraction (EF), end diastolic volume (EDV), and segmental wall motion were made between the preoperative and postoperative catheterization (mean postoperative recatheterization, 6 months). A 2.93 graft per patient ratio was found in this group of patients, with 108/117 grafts visualized at the time of recatheterization. The EF was 60% +/- 3% before surgery and 62% +/- 3% after surgery. A correlation coefficient of 0.91 was determined for the entire series. The EDV was 151 +/- 16 cc before coronary artery bypass graft (CABG) and was unchanged post CABG at an end diastolic volume of 137 +/- 15 cc. Analysis of preoperative wall motion of 33 patients demonstrated 111 depressed segments, 68 normal, and 52 hypercontractile; at recathetrization, there were 100 depressed, 66 normal, and 65 hypercontractile segments. Although there was essentially no deterioration of myocardial function for 37 out of 40 patients, three demonstrated a reduction in EF, the largest reduction being 15%. These three patients had a cardioplegic arrest time greater than 70 minutes. An inverse relationship between percent change in EF and the length of cardioplegic arrest was observed, with an r value o - 0.57 (p less than 0.01). These data suggest that prolonged cardioplegic arrest times may be associated with mild dysfunction. Cold potassium cardioplegic arrest up to 70 minutes was associated with no change in EF, EDV, or wall motion in this series of patients.
Unstable angina pectoris: an examination of modes and costs of therapy.
Authors: Kronenfeld J J , Charles E D , Wayne J B , Oberman A , Kouchoukos N T , Rogers W J , Mantle J A , Rackley C E , Russell R O
Published: June 2012

Debate exists over the most appropriate form of treatment for patients with unstable angina pectoris. This study examined 106 patients randomized at the University of Alabama in Birmingham as part of the National Cooperative Study Group and focuses on the phenomenon of patients who fail medical therapy and thus require late surgery, and the costs of therapy. Discriminant function analysis revealed that the significant predictors (p less than 0.01) of patients who would later require surgery were: total number of vessels diseased, angina severly, presence of congestive heart failure, hypertension, and number of years that the patient had had angina. By means of this analysis, 85% of the late surgery patients were correctly predicted. Late surgery patients averaged 2.4 diseased vessels vs 1.5 for persistent medical patients (p less than 0.01). Mean charges for the first 2 years in the study were $6,226 (SD $2,967) for persistent medical patients, $10,416 (SD $2,146) for surgery patients, and $20,059 (SD $10,748) for late surgery patients (p less than 0.001). These data indicate that surgery is clearly an expensive procedure; but that it is more expensive for late surgery patients, who have total costs that are twice as high as surgical costs and 3.5 times as high as persistent medical costs.
Rate-pressure product and myocardial oxygen consumption during surgery for coronary artery bypass.
Authors: Wilkinson P L , Moyers J R , Ports T , Chatterjee K , Ullyott D , Hamilton W K
Published: June 2012

Rate-pressure product (RPP) is a sensitive index of myocardial oxygen consumption (mVO2) in awake people. We wished to determine whether this relationship persisted under anesthesia and in the face of concurrent large changes in myocardial contractility and left ventricular filling pressures. In 16 patients scheduled for coronary artery bypass surgery, we inserted coronary sinus and Swan-Ganz catheters, and a central aortic catheter via the brachial artery, before induction of anesthesia with either morphine (2 mg/kg) or halothane, chosen in random order. We measured aortic, pulmonary, and venous pressures, cardiac output, systolic time intervals, and thermodilution coronary sinus flow. We calculated mVO2 as coronary sinus flow times myocardial arteriovenous oxygen content difference. We found significant correlations between mVO2 and heart rate (r = 0.57), systolic blood pressure (r = 0.52), the index delta /delta T (r = 0.53, and RPP (r = 0.78). Multiple regression of RPP and delta P/delta T against mVO2 increased their correlation (r = 0.86), while multiple regression of RPP and pulmonary wedge pressure against mVo2 did not significantly improve the correlation of RPP alone (r = 0.75). We conclude that hemodynamic changes anesthesia and surgery do not decrease the sensitivity of RPP as an index of mVO2.
Blood flow in sequential vein grafts.
Authors: McNamara J J , Bjerke H S , Chung G K , Dang C R
Published: June 2012

In 69 patients undergoing coronary artery bypass grafting for complete coronary revascularization, blood flow was measured in 140 grafts with 243 distal anastomoses (3.52 bypasses/patient). Total blood flow in single grafts and double and triple sequential grafts did not differ significantly, although mean distal flow decreased successively with single (85 cc/min), double (51 cc/min), and triple (32 cc/min) sequential grafts. Total myocardial flow did not vary significantly regardless of the number of grafts placed. Flow measurements in patients with double sequential grafts showed greater than 20% overlay in flow between the two distal anastomoses. The data suggest significant but incomplete collateral supply between adjacent coronary beds consistent with the concept of any individual area of myocardium being a capacitance bed supplied in part by a number of adjacent coronary branches.
Survival following mitral valve replacement for mitral regurgitation due to coronary artery disease.
Authors: Radford M J , Johnson R A , Buckley M J , Daggett W M , Leinbach R C , Gold H K
Published: June 2012

Forty-six patients who underwent mitral valve replacement for mitral regurgitation due to coronary artery disease during 1970-1975 were identified. Forty patients underwent aortocoronary bypass procedures at the same operation. The survival rate at the fourth postoperative year was 73% in the 22 patients in whom the preoperative left ventricular ejection fraction exceeded 0.35, 38% in the 16 patients in whom the preoperative left ventricular ejection fraction was 35% or less, and 25% in the eight patients in whom aneurysmectomy was performed at the time of mitral valve replacement (p less than 0.05 for the former group compared to the latter two groups). Heart failure, present preoperatively in 41 patients, was improved in most of the long-term survivors. Neither the angiographic extent of coronary artery disease nor whether mitral valve replacement was performed in the acute (within 2 months in 13 patients) or chronic phase of myocardial infarction were distinctly correlated with survival.
Dispersion of atrial refractoriness in patients with sinus node dysfunction.
Authors: Luck J C , Engel T R
Published: June 2012

Abnormal atrial refractoriness was examined as a cause of atrial fibrillation/flutter (AFF) in patients with bradycardia. Refractory periods at three disparate right atrial sites were compared in 17 patients with sinus node dysfunction (SND) and 16 controls. Atrial pacing shortened refractory periods, but failed to decrease dispersion of refractoriness significantly. During sinus rhythm, duration and dispersion of refractoriness were greater in SND patients than in controls. These differences persisted with atrial pacing. For example, at the paced rate, dispersion of effective refractory periods in SND patients was greater than in controls (62.9 +/- 34 vs 36.6 +/- 21 msec, p less than 0.01). Six SND patients had AFF, but they did not have greater dispersion than other SND patients, or unusually short or long refractory periods. Thus, prolonged and nonuniform refractoriness were features of SND. Abnormal refractoriness in SND reflected atrial disease and persisted with pacing. These abnormalities were not unique to patients with AFF.
Reentry within the atrioventricular node: surgical cure with preservation of atrioventricular conduction.
Authors: Pritchett E L , Anderson R W , Benditt D G , Kasell J , Harrison L , Wallace A G , Sealy W C , Gallagher J J
Published: June 2012

Paroxysmal supraventricular tachycardia (PSVT) is commonly caused by reentry within the atrioventricular (AV) node. This arrhythmia was abolished by operative dissection of the AV junction in a patient with disabling tachycardia that was not controlled by drugs. The operation was intended to create complete AV block, but AV conduction persisted after surgery. An electrophysiologic study 1 year after the operation revealed that the operation changed AV conduction in both the antegrade and retrograde directions, which may explain the absence of tachycardia. The patient has been free of arrhythmias for 18 months.
Multivessel coronary artery spasm.
Authors: Dunn R F , Kelly D T , Sadick N , Uren R
Published: June 2012

A 60-year-old patient with variant angina was shown to have myocardial ischemia in two different regions supplied by separate major coronary arteries. Neither artery had significant coronary atherosclerotic obstruction. Ventricular fibrillation was noted during ST-segment elevation in anteroseptal leads. The attacks of pain and arrhythmias disappeared during nifedipine therapy.
Surgery in active infective endocarditis.
Authors: Young J B , Welton D E , Raizner A E , Ishimori T , Montero A , Guinn G A , Mattox K , Gentry L O , Alexander J K , Miller R R
Published: June 2012

Controversy persists concerning the role of early surgical intervention in severe infective endocarditis (IE). We therefore reviewed 163 episodes of well-documented IE in which 32 cardiac operations were performed during the active phase of IE. Congestive heart failure (CHF) was the principal indication for surgery in 88% (28/32); systemic emboli, 1/32; and persisting sepsis, 3/32. Staphylococcus and enterococcus were the most common infecting organisms in the operative group (44% and 16% respectively). Surgical mortality (11/32,37%) did not differ (p greater than 0.05) from medical mortality (26/131,20%). All 11 operative deaths occurred in patients moribund prior to surgery, including three with preoperative cardiac arrest. Surgical patients undergoing preoperative cardiac catheterization demonstrated marked CHF: a mean left ventricular end-diastolic pressure of 25.3 mm Hg. The mean cardiac index in 8/11 surgical deaths was lower (p less than 0.05) vs surgical survivors: 2.21/min/m2 vs. 3.21/min/m2. Postoperative complications were rare in the 21 surgical survivors. There were no episodes of continued infection, prosthetic dehiscence, or advanced heart block; only one paravalvular leak; and one systemic embolus. These findings emphasize the high medical and surgical mortality in patients with IE, suggest that delayed operative intervention may be a major causative factor resulting in a high surgical mortality, and justify an aggressive surgical approach in patients with valve dysfunction and heart failure. These data indicate that survivors of surgical intervention during active IE have eradication of infection and few postoperative complications.
Oral contraceptive use and fasting triglyceride, plasma cholesterol and HDL cholesterol.
Authors: Hennekens C H , Evans D A , Castelli W P , Taylor J O , Rosner B , Kass E H
Published: June 2012

Fasting plasma triglyceride, plasma cholesterol and high-density lipoprotein (HDL) cholesterol levels were studied for 190 white women, ages 21--39 years, who were classified according to their oral contraceptive (OC) usage patterns at two community surveys, 3 years apart. The mean level of fasting triglyceride was higher among current OC users (95 mg/100 ml) than among nonusers (73 mg/100 ml) (p = 0.002). After adjustment for the possible confounding effects of age, weight, current cigarette smoking and fasting glucose level, current OC users still had a mean plasma triglyceride level 19 mg/100 ml higher than that of nonusers (p = 0.007). Current OC users also appeared to have somewhat higher levels of total cholesterol which were of borderline significance in crude and adjusted analyses. There was a nonsignificant inverse relationship of OC use with HDL cholesterol levels. Past use did not affect these results, indicating that the OC-induced lipid changes were reversible.
Platelet kinetic studies in patients with hyperlipoproteinemia: effects of clofibrate therapy.
Authors: Harker L A , Hazzard W
Published: June 2012

Studies of platelet and fibrinogen kinetics in 27 patients with hyperlipoproteinemia and 28 control subjects demonstrated shortened platelet survival and increased platelet turnover in seven patients with type III and 10 patients with type IV-V hyperlipoproteinemia (p less than 0.01). There was no correlation between platelet survival time and specific lipid levels, vascular disease, sex or age. Platelet kinetics were not significantly altered from control values in eight patients with familial hypercholesterolemia. Platelet aggregation studies and fibrinogen kinetic measurements did not differ in any of the hyperlipoproteinemic groups of patients from those in control subjects. Despite significant changes in plasma lipids induced by clofibrate, platelet survival was significantly extended only in patients with type IV-V hyperlipoproteinemia (p less than 0.05). These results are consistent with the hypothesis that atherogenesis in patients with types III--V hyperlipoproteinemia may be associated with a process of endothelial desquamation, and type IIa hyperlipoproteinemia may involve nondesquamating endothelial injury.
Platelet function studies in heart disease. VI. Enhanced platelet aggregate formation activity in congestive heart failure: inhibition by sodium nitroprusside.
Authors: Mehta J , Mehta P
Published: June 2012

We studied 11 patients with congestive heart failure and 10 normal volunteers for in vivo platelet aggregate formation activity. The patients with heart failure had significantly (p less than 0.01) more circulating platelet aggregates than the normal volunteers. During sodium nitroprusside infusion, the number of circulating platelet aggregates declined to normal levels and in vitro platelet aggregation responses to epinephrine and adenosine diphosphate were also suppressed significantly (p less than 0.01). This was associated with a 30% decline in systemic vascular resistance and a 28% increase in cardiac output. In other in vitro experiments, sodium nitroprusside was found to have direct, dose-related platelet aggregation inhibitory actions. This study suggests that an increase in vascular resistance in certain heart failure patients may in part be related to an increase in circulating platelet aggregates. Direct inhibition of platelet aggregation by sodium nitroprusside may be a mechanism of its beneficial effects in heart failure.
The estimation of sinoatrial conduction time in rabbit heart by the constant atrial pacing technique.
Authors: Grant A O , Kirkorian G , Benditt D G , Strauss H C
Published: June 2012

This study compared estimates of sinoatrial conduction time (SACT) obtained by constant atrial pacing (CAP) and premature atrial stimulation (PAS) with measured SACT in isolated rabbit right atrial preparations. Transmembrane potentials and surface electrograms were recorded from the sinus node and crista terminalis, respectively. The crista terminalis was paced 5, 10 and 15 beats/min faster than the spontaneous sinus rate with a train of eight pulses. Estimate of SACT by CAP was taken as the difference between the first atrial return cycle and the mean spontaneous cycle length. SACTs at 5, 10 and 15 beats/min faster were 76 +/- 10, 86 +/- 10 and 96 +/- 10 msec (mean +/- SEM; n = 12), respectively; correlation coefficients with the true SACT were 0.7, 0.54 and 0.4. Consecutive determinations of SACT by PAS and CAP in the same preparation (n = 6) at 10 beats/min faster gave SACTs of 86 +/- 13 and 79 +/- 14 msec, respectively, compared with true SACTs of 79 +/- 10 msec. Shortening of sinus node action potential, depression of automaticity and shifts in the site of the primary pacemaker contributed to the errors in both techniques. Estimation of SACT by CAP may be further complicated by failure of sinus node capture. Principles to minimize some of these errors are also presented.
Valve replacement for aortic regurgitation: long-term follow-up with factors influencing the results.
Authors: Samuels D A , Curfman G D , Friedlich A L , Buckley M J , Austen W G
Published: June 2012

One hundred consecutive cases of valve replacement for aortic regurgitation performed between 1967--1971 were analyzed to identify and quantitate factors related to a favorable result. Of 83 perioperative survivors, 78% (n = 65) became asymptomatic and 58% (n = 48) were alive 5--9 years postoperatively. The cause of aortic regurgitation affected both the speed of progression of symptoms and the postoperative result. Death due to myocardial failure may be prevented by optimal timing of operation. Accordingly, we identified variables that discriminated between patients who had an excellent postoperative result and those who died of myocardial failure. The most important discriminators were the severity (p = 0.03) and duration (p = 0.04) of dyspnea, the extent of therapy for heart failure (p = 0.001), physical findings of left ventricular failure (p = 0.002), the cardiothoracic ratio (p = 0.007), the resting pulmonary capillary wedge pressure (p = 0.01), and a cardiac index less than 2.2 1/min/m2 (p = 0.03). The data suggest that evidence of left ventricular failure, even of mild degree, is an indication for operation in patients with severe aortic regurgitation.
Dynamic exercise echocardiography.
Authors: Sugishita Y , Koseki S
Published: June 2012

To evaluate left ventricular (LV) reserve, we developed a method of dynamic exercise echocardiography (DEE). Forty-six healthy persons and 47 cardiac patients performed bicycle ergometer exercise in the supine position. A special table was used on which the subjects could be firmly attached at shoulder level to prevent bodily movements which might disturb the recordings. In 83% of the subjects in whom a clear echocardiogram was obtained at rest, a clear echocardiogram was also obtained during dynamic exercise. During exercise, cardiac output estimated from the echocardiogram and that from the dye-dilution method showed an excellent correlation. The changes of the mean velocity of LV circumferential shortening during exercise permitted discrimination between older and younger healthy men, and also between healthy subjects and those with either mild or severe LV dysfunction. We conclude that DEE is useful for evaluating LV reserve.
Pathologic basis of thallium-201 scintigraphic defects in patients with fatal myocardial injury.
Authors: Bulkley B H , Silverman K , Weisfeldt M L , Burow R , Pond M , Becker L C
Published: June 2012

Using a quantitative, computer-aided circumferential profile technique, we have shown that thallium-201 scintigrams with large defects can identify a group of patients with a high mortality after acute myocardial infarction. To determine whether high-risk thallium scintigrams predict poor survival because of a critical loss of myocardium, we correlated infarct size in 24 autopsied patients with the extent of thallium defect in three views. Of 13 patients with large defects (computer score greater than or equal to 7.0) eight (62%) had greater than 25% loss of left ventricular (LV) myocardium, but five (38%) had smaller infarcts (4--24% of LV myocardium), suggesting that part of the scintigraphic defect was related to ischemia without necrosis. Eight of the nine patients with loss greater than or equal to 25% LV myocardium had large defects. In 10 of 11 patients with small defects (computer score less than 7.0), infarcts involved less than 20% of LV myocardium. Although scintigrams with large defects predicted a critical loss of myocardium in over 60% of our patients, they included an important second group, in which the scintigraphic defect appeared to reflect a small infarct and a large surrounding area of reversibly ischemic myocardium.
The effects of coronary artery disease on the ventricular fibrillation threshold in man.
Authors: Horowitz L N , Spear J F , Josephson M E , Kastor J A , Moore E N
Published: June 2012

The ventricular fibrillation threshold (VFT) was measured in 28 patients at the time of cardiac surgery. The VFT was measured with a 100 Hz train of 24 rectangular pulses positioned across the ST segment and T wave. Current was applied to the epicardial surface of either ventricle with a bipolar electrode probe. In six patients, the normal right VFT was 24.3 +/- 5.2 mA, and in 10 patients the normal left VFT was 33.6 +/- mA (p less than 0.05). In 12 patients with greater than or equal to 75% obstruction of the left anterior descending coronary artery, the left VFT was 18.6 +/- 6.9 mA. This value was significantly less than the left VFT in patients without coronary artery disease (p less than 0.001). This study shows that the VFT can be measured in man and that coronary artery disease reduces this parameter.
Suppression of chronic ventricular arrhythmias with propranolol.
Authors: Woosley R L , Kornhauser D , Smith R , Reele S , Higgins S B , Nies A S , Shand D G , Oates J A
Published: June 2012

The antiarrhythmic efficacy of propranolol was evaluated in 32 patients with chronic high frequency ventricular arrhythmias in a placebo-controlled protocol. After a placebo control period, propranolol was begun and the dosage increased sequentially until arrhythmia suppression was achieved, side effects appeared, or a maximum dosage of 960 mg/day was reached. Computerized analysis of ambulatory recordings was used to quantify the arrhythmias. Twenty-four patients had 70--100% arrhythmia suppression at plasma levels ranging from 12--1100 ng/ml (end of dosing interval). Eight patients in this group had frequent episodes of ventricular tachycardia that were totally suppressed at or below the dosage that produced greater than or equal to 70% suppression of ventricular ectopic depolarizations (VEDs). A biphasic dose-response curve was seen in five patients who responded with a decrease in arrhythmia frequency in the lower ranges of dosages but had increased frequency of ectopic rhythms as the dosage was increased above the optimal level. Only one-third of patients responded at doses less than or equal to 160 mg/day. However, with dosages of 200--640 mg/day, an additional 40% responded. Propranolol appears to control ventricular arrhythmias safely and effectively in many patients. The finding that the antiarrhythmic effect in many patients required plasma concentrations greater than those that produce substantial beta-adrenergic blockage raises a question whether blockade of cardiac beta receptors can directly account for all of the antiarrhythmic actions of propranolol.
Characteristics of ventricular function in single ventricle.
Authors: Kitamura S , Kawashima Y , Shimazaki Y , Mori T , Nakano S , Beppu S , Kozuka T
Published: June 2012

Funtional characteristics of the single ventricle were studied by means of biplane angiocardiography in 34 patients. Group 1 consisted of 14 patients with normal or increased pulmonary vascular marking on chest film and no pulmonary stenosis. Group 2 included 20 patients with severe angiographic pulmonary stenosis and decreased pulmonary vascular marking. Ventricular volume parameters were calculated according to Simpson's rule and were compared with normal values. The sum of the normal left and right ventricular volumes was assumed to be 100%. In group 1, ventricular end-diastolic volumes averaged 143 +/- 11% and were significantly (p less than 0.001) larger than end-diastolic volumes in group 2 (81 +/- 4%). The presence or absence of severe pulmonary stenosis affecting pulmonary blood flow was a main factor regulating the ventricular chamber size in single ventricle. In both groups, the ejection fraction of a single ventricle was significantly lower than that of a normal left or right ventricle. Ventricular size and function in patients with a single ventricle should be carefully assessed before ventricular septation surgery.
Determination of His-Purkinje refractoriness in man with His bundle pacing.
Authors: Peters R W , Scheinman M M , Raskin S , Desai J
Published: June 2012

Consistent His bundle pacing was accomplished in one of 60 consecutive patients. Intracardiac electrophysiologic studies in this patient revealed rapid atrioventricular nodal conduction (AH = 55 msec). While the relative refractory period of the His-Purkinje system as a whole determined by His bundle pacing (using the extrastimulus technique) was identical to that determined by atrial pacing, changes in right bundle branch refractoriness differed. An atrial extrasystolic interval of 370 msec resulted in right bundle branch block, whereas direct His pacing at a shorter extrasystolic interval (360 msec) failed to produce a bundle branch block pattern. The effective refractory period of the His-Purkinje system could not be determined by atrial pacing because of atrial refractoriness, but was obtained by His bundle pacing. Theoretically, direct His bundle pacing may be of value in determining His-Purkinje system refractoriness when this parameter is unobtainable due to either atrial or atrioventricular nodal refractoriness. This technique appears to have limited clinical usefulness, however, because of the very small success rates. Finally, His-Purkinje system refractoriness may differ, depending on site of stimulation, presumably due to differing inputs into the His-Purkinje system.
Interventricular septal thickness and left ventricular hypertrophy. An echocardiographic study.
Authors: Kansal S , Roitman D , Sheffield L T
Published: June 2012

Septal and left ventricular posterior wall (LVPW) thicknesses and their ratios were studied at the left ventricular outflow tract and left ventricular cavity in 66 patients with echocardiographically diagnosed left ventricular concentric hypertrophy, 20 with idiopathic hypertrophic subaortic stenosis (IHSS), and 34 normal subjects. Concentric hypertrophy was due to hypertension in 41 subjects and to valvular disease in 15 subjects. Septal thickness in normal subjects was related to body surface area (p less than 0.02). In 12% of normal subjects, 39% of patients with concentric hypertrophy and 95% with IHSS, the septal/LVPW ratio was greater than or equal to 1.3. Thirty-two percent of patients with hypertension, 78% with aortic stenosis, and 60% with aortic insufficiency had septal/LVPW ratios greater than or equal to 1.3 at left ventricular midcavity level. In conclusion, a septal/LVPW thickness ratio of greater than or equal to 1.3 is common in patients with concentric left ventricular hypertrophy and may also occur in normal subjects. A ratio greater than or equal to 1.5 may be more specific for genetically determined asymmetric septal hypertrophy.
Histology of pulmonary arterial supply in pulmonary atresia with ventricular septal defect.
Authors: Thiene G , Frescura C , Bini R M , Valente M , Gallucci V
Published: June 2012

A histologic study was performed on 22 specimens of pulmonary atresia with ventricular septal defect to 1) ascertain the existence of the main pulmonary artery; 2) distinguish the ductus arteriosus from the systemic collateral arteries (SCA); 3) establish the nutritive or functional nature of collateral circulation; and 4) evaluate the morphology of the distal pulmonary bed. Three cases had absent main pulmonary artery, one with and two without signs of infundibular septation. We suggest that absent main pulmonary artery may exist with both infundibular pulmonary atresia and persistent truncus arteriosus. SCAs have been found to have similar histological features as systemic muscular arteries of the same size--their medial muscular layer merges gradually into an elastic one at different depth inside the lungs. Injection of contrast material allowed us to demonstrate that these vessels are functional, since they inosculate into efficient pulmonary arteries ending in the respiratory units. When the distal pulmonary vascular bed is perfused by large SCAs, proliferative lesions like those found in large left-to-right shunts may occur. Early in infancy, banding of large, nonstenotic SCAs could protect the distal pulmonary vasculature. Moreover, total surgical repair should be associated with ligation of the SCA to avoid residual left-to-right shunt, if the pulmonary arteries can carry the full pulmonary blood flow.
Effects of acute hemodynamic alterations on pulmonic valve motion. Experimental and clinical echocardiographic studies.
Authors: Kerber R E , Martins J B , Barnes R , Manuel W J , Maximov M
Published: June 2012

The purpose of this study was to assess the effects of acute alterations of the pulmonary circulation on the pulmonic valve echocardiogram. We measured the pulmonic valve opening velocity (PVOV) and right-sided systolic time intervals (right ventricular preejection period-to-right ventricular ejection time ratio [RPEP/RVET] in 22 open-chest dogs subjected to acute hemodynamic alterations produced by inferior vena cava constriction, atrial pacing, isoproterenol infusion and microsphere embolization of the pulmonary artery. We found only fair correlations between PVOV and peak pulmonary artery flow (r = 0.56), right ventricular dp/dt (r = 0.43), stroke volume (r = 0.42), pulmonary artery systolic pressure (r = 0.33) and peak pulmonary artery acceleration (r = 0.31). RVET was shortened by reduced venous return (caval constriction) and by increases in heart rate (atrial pacing and isoproterenol), which resulted in increases in RPEP/RVET that did not correspond well to simultaneous changes in pulmonary artery pressure. In seven patients breathing 10% O2 to raise pulmonary artery pressure acutely, we found no change or a fall in PVOV. Thus, the pulmonic valve echocardiogram is influenced by multiple factors relating to parameters of pulmonary flow and right ventricular contractility, and may be of limited clinical usefulness in predicting pulmonary artery pressures.
Effect of moderate physical exercise on serum lipoproteins. A controlled clinical trial with special reference to serum high-density lipoproteins.
Authors: Huttunen J K , Länsimies E , Voutilainen E , Ehnholm C , Hietanen E , Penttilä I , Siitonen O , Rauramaa R
Published: June 2012

A controlled trial is reported on the effects of mild-to-moderate physical activity on serum lipoproteins. After two baseline examinations 100 asymptomatic middle-aged men were randomly assigned to exercise and control groups. The exercise group participated in a 4-month exercise program that consisted of 3-4 weekly sessions. The control group was advised to maintain their previous exercise habits. The success of the program was corroborated by the increase in VO2 in the training group, but not in the control group. Serum triglycerides decreased from 1.54 +/- 0.10 to 1.27 +/- 0.08 mmol/1 (p less than 0.001) and high-density lipoprotein (HDL) cholesterol increased from 1.27 +/- 0.04 to 1.41 +/- 0.04 mmol/1 (p less than 0.01) in the exercise group during the trial. No change was seen in the control group. As the concentration of apolipoprotein AI stayed constant in both groups, the ratio HDL cholesterol/apolipoprotein AI increased only in the exercise group. The level of low-density lipoprotein (LDL) cholesterol and apolipoprotein AII decreased in both groups during the trial. The alterations in serum triglycerides and HDL cholesterol in the exercise group were not dependent on weight reduction; similar changes were also seen in subjects with constant body weight during the intervention.
The prognostic significance of serial exercise testing after myocardial infarction.
Authors: Sami M , Kraemer H , DeBusk R F
Published: June 2012

Serial treadmill exercise testing (mean 5.5 tests/patient) was used to evaluate the prognosis of 200 males (mean age 53 years) without clinical heart failure or unstable angina pectoris 3 weeks after acute myocardial infarction (MI). Exercise-induced ischemic ST-segment depression greater than or equal to 0.2 mV 3 weeks after MI was significantly more prevalent in patients with subsequent cardiac arrest (100%) or coronary artery bypass graft surgery (64%) than in patients without subsequent events within 2 years of infarction (35%) (p less than 0.05). Exercise-induced ventricular arrhythmia on multiple tests 5-52 weeks after MI was more prevalent in patients with recurrent myocardial infarction (90%) than in patients without subsequent events (47%) (p less than 0.001). By contrast, exercise-induced ventricular arrhythmia on a single test at 3 weeks was a less powerful predictor of subsequent cardiac events. Exercise-induced ischemia 3 weeks after MI predicted early fatal events, while ventricular arrhythmia on serial testing predicted later nonfatal events.
Cardiovascular responses to repeated treadmill exercise testing soon after myocardial infarction.
Authors: Haskell W L , DeBusk R
Published: June 2012

To determine the response to repeated treadmill exercise testing soon after uncomplicated myocardial infarction, 24 males (mean age 54 +/- 6 years) performed two symptom-limited tests several days apart 3, 7 and 11 weeks after the acute event. Significant within-week differences were noted for peak exercise tolerance (mets) and peak heart rate at 7 weeks (p less than 0.05). Significant within-week differences in these variables were not noted for other weeks or for systolic blood pressure or heart rate-systolic blood pressure product for any of the three test periods. No significant within-week differences were noted for any variable recorded at a submaximal work load of 4 mets. The frequency of exercise-induced ischemic ST-segment depression, angina pectoris and premature ventricular complexes did not change from visit to visit and was highly reproducible (p less than 0.01). All test variables measured at peak exercise increased significantly between 3 and 11 weeks after infarction. We conclude that cardiovascular responses to symptom-limited exercise testing are highly reproducible in the 3 months after uncomplicated myocardial infarction. Changes in the response to treadmill exercise tests performed several weeks apart reflect alterations in cardiovascular performance.
Exercise cross-sectional echocardiography in ischemic heart disease.
Authors: Wann L S , Faris J V , Childress R H , Dillon J C , Weyman A E , Feigenbaum H
Published: June 2012

We performed cross-sectional echocardiograms at rest, during supine bicycle exercise, and after sublingual nitroglycerin administration in 28 patients suspected of having ischemic heart disease. Technically adequate exercise cross-sectional echocardiograms were obtained in 20 patients (71%). Ten patients had new areas of reversible segmental dysynergy, and all 10 had significant stenoses of coronary arteries supplying areas of the heart corresponding to the location of reversible dysynergy. Six of these 10 patients also underwent exercise thallium-201 perfusion scanning, and all six had reversible perfusion defects in the area that demonstrated reversible dysynergy on exercise cross-sectional echocardiography. At least two of the remaining 10 patients who did not have reversible segmental dysynergy on exercise cross-sectional echocardiography probably experienced myocardial ischemia that we did not detect. We conclude that exercise cross-sectional echocardiography is technically difficult but feasible. The mechanical consequences of exercise-induced regional myocardial ischemia can be detected noninvasively by real-time, two-dimensional, cross-sectional echocardiography.
Comparative value of eight M-mode echocardiographic formulas for determining left ventricular stroke volume. A correlative study with thermodilution and left ventricular single-plane cineangiography.
Authors: Kronik G , Slany J , Mösslacher H
Published: June 2012

Sixty-six consecutive patients without left ventricular volume overload, significant arrhythmia or significant pericardial effusion were examined by M-mode echocardiography immediately before diagnostic left- and right-heart catheterization. Using various echocardiographic measurements, left ventricular stroke volume (SV) was calculated according to eight different echocardiographic formulas (SVE) that have been proposed previously. At catheterization SV was also determined by thermodilution (SVT) and by single-plane left ventricular cineangiography in the right anterior oblique projection (SVA). When comparing SVE with SVT, the four formulas developed to calculate mitral or aortic flow failed (r = 0.10 to 0.54). As expected, poor correlations (r = 0.22 to 0.47) were also found when formulas used to calculate ventricular volumes from the ventricular diameter or SV from the change in diameter (left ventricular formulas) were used in coronary patients with grossly asymmetrical ventricular contraction patterns. When the use of the left ventricular formulas was confined to patients with symmetrical or almost symmetrical contraction, two formulas yielded favorable correlations of r = 0.84, SEE = 12.7 ml and r = 0.86, SEE = 12.2 ml, respectively. These correlations were comparable to the correlation between our two invasive reference techniques (r = 0.81; SEE = 12.2 ml). The comparison between SVE and SVA confirmed the results of the thermodilution study, though the correlations were generally weaker. We conclude that the formula of Teichholz et al., which was the best of all tested formulas, may be used to obtain a clinically useful estimate of SV in patients in whom symmetrical or almost symmetrical left ventricular contraction can be anticipated.
Distinguising features of left anterior fascicular block and inferior myocardial infarction as presented by body surface potential mapping.
Authors: Sohi G S , Flowers N C
Published: June 2012

Total body surface maps obtained from 19 patients with previous inferior myocardial infarction (IMI) were compared with maps obtained from 19 patients with left anterior fascicular block (LAFB) and six more patients in whom electrocardiographic changes were indistinguishable between IMI and LAFB. Three distinguishing features were detected: 1) abnormal high anterior positivity developed both in IMI and LAFB, but its onset was earlier in LAFB; 2) a broad rim of abnormal right lower negativity was seen in both groups, but in IMI it was within the first 40 msec, whereas in LAFB it was found in the middle and later parts of depolarization; 3) abnormal left lower negativity was seen in all the patients with LAFB, but was absent in IMI. Thus, despite similarities in the abnormalities detected, we found definite temporal and topographical differences that should aid in differentiating between IMI and LAFB in ambiguous cases.
Atrioventricular block and supraventricular arrhythmias with X-linked muscular dystrophy.
Authors: ul Hassan Z , Fastabend C P , Mohanty P K , Isaacs E R
Published: June 2012

This report describes a family showing muscular dystrophy and atrioventricular block with an x-linked hereditary transmission. Among a known pedigree of 101 family members, 12 males were found to have skeletal muscle involvement and six needed pacemakers around age 30 years. Unlike the x-linked muscular dystrophies of Duchenne and of Becker, the predominant skeletal involvement was in humeral muscles, was usually very mild, and did not produce incapacitation. Cardiac involvement consisted of various atrial arrhythmias and atrioventricular block. The few sporadic reports of other families that describe the same disease under different names are briefly reviewed. Recognition of this subtle muscular dystrophy is important for early detection of incipient complete atrioventricular block to prevent fatal complications by pacemaker insertion.
Endocardial excision: a new surgical technique for the treatment of recurrent ventricular tachycardia.
Authors: Josephson M E , Harken A H , Horowitz L N
Published: June 2012

Twelve patients with medically refractory ventricular tachycardia secondary to ischemic heart disease underwent surgery for cure of their arrhythmia. Preoperatively, the tachycardia could be reproducibly initiated and terminated in each patient by programmed stimulation. In all instances, intraoperative mapping localized the tachycardia to the border of the aneurysm, a site not routinely resected during aneurysmectomy. In nine instances, the area of origin involved the septum. During bypass the tachycardia could still be induced after standard aneurysmectomy or ventriculotomy in 11 of 12 patients. On the basis of intraoperative mapping, resection of endocardium in the area of origin (25--40% the circumference of the aneurysmectomy) up to normal muscle was performed. In one patient without a discrete aneurysm, endocardial excision alone through a ventriculotomy was performed. There was one operative death due to cardiogenic shock (preoperative ejection fraction 5%) and one late death due to rupture of a mycotic aneurysm in the pulmonary artery. Before discharge, all patients underwent a repeat relectrophysiologic study off antiarrhythmic agents and in none could ventricular tachycardia be initiated. Hemodynamic and angiographic catheterization showed improved hemodynamics and ejection fractions in all. The 10 survivors remained free of sustained ventricular tachycardia for 9--20 months, with one late nonarrhythmic death.
Increased circulating bradykinin during hypothermia and cardiopulmonary bypass in children.
Authors: Pang L M , Stalcup S A , Lipset J S , Hayes C J , Bowman F O , Mellins R B
Published: June 2012

To determine whether cold could activate the kallikrein-kinin system in vivo as it does in vitro, the circulating systemic concentrations of bradykinin were serially measured in 10 cyildren with congenital diseases of the heart undergoing corrective cardiac surgery. Bradykinin was measured by radioimmunoassay in blood samples obtained before, during and after profound hypothermia (to 18 degrees C) and cardiopulmonary bypass. The circulating concentrations of bradykinin increased significantly as body temperature decreased during surface cooling. The increase in circulating bradykinin was associated with a decrease in the circulating level of bradykininogen, the precursor of bradykinin. With the onset of cardiopulmonary bypass and hence, removal of the lung and pulmonary converting enzyme from the circulation, there was a further rise in the already elevated concentrations of bradykinin. This is the first in vivo demonstration that hypothermia leads to an increase in the circulating concentrations of bradykinin.
Research related to medical treatment of cardiovascular disease.
Authors: Ross R S
Published: June 2012

Medical treatment of heart disease has improved significantly in the past 30 years. The spectacular change in the natural history of rheumatic heart disease is apparent from a 1948 article that reported that 42% of children with rheumatic heart disease died of rheumatic infection or bacterial endocarditis. Antibiotics and cardiac surgery have improved the outcome from rheumatic heart disease. Cardiopulmonary resuscitation has had a major impact on the treatment of myocardial infarction and on the management of sudden death. The fundamental principle underlying the discovery of cardiopulmonary resuscitation is reviewed, and recent developments emphasizing the importance of intrathoracic pressure in the hemodynamics of cardiopulmonary resuscitation are highlighted. The important new drugs of the last 30 years include the oral diuretics, the antihypertensives and the antiarrhythmic agents. The development of the beta-blocking agents is cited as an example of the translation of basic physiological research to medical care. Finally, the role of epidemiologic techniques in the design of clinical trials to evaluate medical therapy and hence improve medical management is discussed.
Research related to rehabilitation.
Authors: Wenger N K
Published: June 2012

Progress in cardiac rehabilitation demands that rehabilitation efforts for the patient after myocardial infarction or aortocoronary bypass surgery be integrated into a comprehensive program of acute and ambulatory cardiac care. To permit a more rapid return of coronary patients to a normal or near-normal lifestyle and role in society, further delineation of the scientific bases for all components of rehabilitation programming and identification of both barriers to and facilitators of rehabilitation are necessary to improve rehabilitative services.